Difficult load

[Pieoftheday]

I've often read reviews about speakers that are a difficult load, need lots of power to sound their best,why aren't all speakers an easy load :scratch: perhaps this is a stupid question if you're an expert, but I'm clearly not! I'm just interested to know? Jim

[Firebottle]

A difficult load tends to be one that has big dips in the impedance across the frequency range.

An example
http://www.stereophile.com/images/archivesart/Lsfig6.jpg
This is a very low impedance above 3KHz compared to the lower frequencies.
The variation is going to depend on the driver units used plus the possible complexity of the crossover.

:)

[walpurgis]

Yup. Try running a pair of big vintage Apogee ribbons with the average amp.

[Pieoftheday]

But why make a 'difficult load'?

[anji12305]

It's a consequence of cabinet design and exotic drivers used to solve problems of size, frequency response and dynamics.

Most audio gear is up against the limit of material science, and relies on electromagnetic "motors".

When these move, current tries to flow away from the amp and back into the amp, which makes the signal vary.

This change in phase angle can make instantaneous demands for current that stress or damage amplifiers.

It's like tuning a car for performance; more output=shorter service intervals.

Lower output=lower part failures.

Sent from my Nexus 6 using Tapatalk

[Pieoftheday]

It's a consequence of cabinet design and exotic drivers used to solve problems of size, frequency response and dynamics.

Most audio gear is up against the limit of material science, and relies on electromagnetic "motors".

When these move, current tries to flow away from the amp and back into the amp, which makes the signal vary.

This change in phase angle can make instantaneous demands for current that stress or damage amplifiers.

It's like tuning a car for performance; more output=shorter service intervals.

Lower output=lower part failures.

Sent from my Nexus 6 using Tapatalk

That kind of makes sense to my uneducated mind, but,if some really good speakers can be easy to drive, why bother making hard to drive ones? Are there advantages?

[Arkless Electronics]

There's no advantage in making a speaker hard to drive but some technologies and methods end up making the speaker hard to drive as a "side effect". The Apogees for example are ribbon drivers and some of the old ones IIRC use no transformer to step up the impedance of the speakers to a level that most amps can cope with. Why? because the transformers themselves would seriously degrade the sound quality.
The graph that Alan posted looks like it could well have an electrostatic tweeter or even be a full electrostatic speaker. The low impedance is due to the capacitive nature of such speakers. The impedance drops with frequency intrinsically, it's not done to deliberately stress amps or anything!

[anthonyTD]

Also,
Some manufacturers use inferior designed drive units, and use over complicated cross-overs in an atempt to curb, and control the non linear response of the drivers.
A bit like closing the gate after the horse is gone!
Its much easier, and cheaper it would seem in many cases, to put a speaker together in this way, than to use carefuly designed drive units, and pair them respectfuly, without the need for complicated, and in many cases severely compromised cross-over designs.
A...

[Pieoftheday]

There's no advantage in making a speaker hard to drive but some technologies and methods end up making the speaker hard to drive as a "side effect". The Apogees for example are ribbon drivers and some of the old ones IIRC use no transformer to step up the impedance of the speakers to a level that most amps can cope with. Why? because the transformers themselves would seriously degrade the sound quality.
The graph that Alan posted looks like it could well have an electrostatic tweeter or even be a full electrostatic speaker. The low impedance is due to the capacitive nature of such speakers. The impedance drops with frequency intrinsically, it's not done to deliberately stress amps or anything!
Thanks jez, thats an answer that makes a sort of sense:)
To me at least

[RothwellAudio]

But why make a 'difficult load'?

I think manufacturers tend to think within their own box. For example, moving coil cartridge manufacturers will design a cartridge with such a low output that it becomes very difficult to amplify with a good signal-to-noise ratio, but that's not their problem, is it?
Loudspeaker manufacturers seem to assume that their loudspeakers will be driven by amplifiers which will maintain full power output and never complain when faced with a short circuit or a highly capacitative load or a bucket of water. In order to give the flattest frequency response they will design crossovers which smooth out the frequency nicely despite the impedance curve going up and down like a bride's nighty and nearly giving the amplifier a heart attack, but that isn't their problem. is it?

[JohnJo]

A difficult load tends to be one that has big dips in the impedance across the frequency range.

An example
http://www.stereophile.com/images/archivesart/Lsfig6.jpg
This is a very low impedance above 3KHz compared to the lower frequencies.
The variation is going to depend on the driver units used plus the possible complexity of the crossover.

:)

Very interesting. I know there are capacitors in the crossover filters but since the drive units are coils I always assumed loudspeaker impedance was inductive, i.e. current lagging the voltage but this shows massive swings both ways. Is this normal in speakers with ordinary drive units or just electrostatics, and if so is this due to back emf on a driver's return stroke? Do the crossover capacitors contribute?

[anji12305]

It's important to understand that building a good sounding speaker for low cost is VERY difficult, even with cheap labor. Plenty of interesting, good sounding designs fail to sell.

The genius is in making it simple ad possible, but no simpler.

Complex loads may be presented by very good sounding speakers.

There are more inexpensive, stable and good sounding amps available today, than ever before.

The real challenge is getting good bass from small drivers and dealing with the consequences.

Sent from my Nexus 6 using Tapatalk

[anji12305]

That kind of makes sense to my uneducated mind, but,if some really good speakers can be easy to drive, why bother making hard to drive ones? Are there advantages?
Really easy loads that play loudly, with decent frequency extension (high and low) tend to be pretty large. See Altec Voice of the Theater

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[danilo]

But why make a 'difficult load'?

Really!?
Because those are Wayyy Cheaper to design /build.
Profit mate... naught else.

[Reffc]

As with all else "hifi" it's not something that is easy to generalise about.

Put simply, loudspeakers are all a compromise by dint of design and the constraints on "perfect" performance. Smaller enclosures using smaller drive units tend to suffer lower efficiency & sensitivity leading to greater power needed to match SPLs of larger designs. Simple crossovers done badly can lead to severe dips in impedance at crossover. The Impulse H2 has a severe dip at between 1600Hz and 2.2KHz dropping to just 2.8 Ohms due to a poor crossover design.

Over-complex crossovers, typically 4th order or higher, needed to tame high break up resonances of (mainly) mid and mid-bass units and woofers have very steep electrical and acoustic slopes which band-width limit any severe impedance dips BUT typically suffer reduced sensitivity due to more power-sapping inductors in the signal path.

There are a few misunderstandings on this thread though. Just because a loudspeaker design may not be especially sensitive, the load that it presents may still be viewed as relatively benign, but the power requirements for a given SPL will be greater than for a 'speaker of higher sensitivity. That doesn't worry any amp that can drive such designs happily to moderate volumes and is easy enough to specify in terms of amplifier requirements.

What is less obvious are the effects of both impedance swings, overall (nominal) impedance, and phase swings. Moderately low impedance speakers of say 4 Ohms combined with high phase swings especially in the bass region will be very demanding of the partnering amplifier and such designs usually require significantly more power than one might be led to believe to prevent clipping.

The final issue is one of damping factor. The DF is determined by taking the loudspeaker's minimum impedance and dividing it by the sum of the amplifier's output impedance plus losses up to the voice coil of the loudspeaker, including cable and crossover losses. Anything much under 7 or 8 as a DF will not adequately control a loudspeaker's low frequency which will become ploddy, overblown and rather muddy. The inertia and back EMF from the drive unit puts a load on the amp in these cases, which it cannot adequately control. The answer here is to use an amplifier with a higher damping factor (low output impedance) but sometimes whatever amp is used, the losses within the crossover combined with high "Q" drive units just wont work well, so it can be viewed as poor design. There are, unfortunately, many such designs in hifi land, all best avoided.

The last consideration when discussing, say, efficiency of loudspeakers is that of small V's large:

The smaller the drive unit, the less efficient it is at coupling its energy with the air in front of it. Efficiency is a measure of output power over input power, in watts, and is typically 1% or less. The impedance mis-match is one of physical mis-match between the drive unit and the air that it couples to. The second point is directivity, or axial V's non-axial efficiency which varies with speaker drive unit size and design, hence efficiency doesn't necessarily correlate with sensitivity. What you can say as a generalisation is that for two comparable cabinet designs, a smaller enclosure using smaller drive units may be less efficient than a larger drive unit for the same given SPL.

[struth]

Good post Paul

[Macca]

It is, and is probably why so many speaker journeys end up with big Tannoy dual-concentrics. They are possibly the best balance of all the various compromises.

[anthonyTD]

:)
It is, and is probably why so many speaker journeys end up with big Tannoy dual-concentrics. They are possibly the best balance of all the various compromises.

[Reffc]

It is, and is probably why so many speaker journeys end up with big Tannoy dual-concentrics. They are possibly the best balance of all the various compromises.

I tend to agree Martin which is why I've ended my loudspeaker journey with some well sorted DCs. The obvious compromise is cabinet size!

[jandl100]

Well, that's a -1 for me. :lol:

I can't stand Tannoy DCs!

[anthonyTD]

That's cos your deaf! :D
Seriously though, I would like to hear some MBL's one day.:)
A...
Well, that's a -1 for me. :lol:

I can't stand Tannoy DCs!

[DSJR]

We audiophile types like to mix and match gear to a personal taste and budget. The pros abandoned this years ago and went active. Another can-o-worms here, but so much of this easy-difficult load is removed at a stroke because the amps are seeing the drive units directly with nothing in between to screw it up. Of course, the active crossover network before the amp has to be designed to be as sonically invisible as possible and various opinions abound on that score, which I'm not really qualified to comment about.

There is a move in one or two traditional UK speaker manufacturers to seriously look at the crossover designs they use and to make them as least intrusive as possible if not as simple as possible. I think they're only part way along this journey myself, but that's merely an opinion.

Last option is to design the drivers so they don't 'need' a crossover at all (apart from tweeters, which do need protection from low frequencies). Classic Epos models (ES14 and ES11) showed the basics of what could be done and the heavily treated/doped NVA drivers are another good one, currently causing me great grief as well as pleasure, because hearing an unfettered driver doing the music communication thing so clearly with a standard power amp, without being slugged by coils, resistors and caps is an education in itself.

[anji12305]

Well, that's a -1 for me. [emoji38]

I can't stand Tannoy DCs!
Beaming artifacts?

I've also tried Coaxial designs, and come away unsatisfied. I think the real challenge is in getting the HF driver to crossover at a meaningfully low point, or in using a smaller LF driver across the vocal band.

Large LF will "shout" as their directivity narrows with rising frequency.

It is my suspicion that the much appreciated KEF LS50 is an example of a broadband LF driver crossed over high enough that the HF unit can play the rest without distortion or overload.

There's a reason KEF Uni-Q are smaller than classic Tannoy designs.



Sent from my Nexus 6 using Tapatalk

[Macca]

Go fully active with digital crossovers and you side-step all of these problems, and you don't need several grands worth of vintage dual concentric drivers either. I think this will replace the Tannoy hegemony eventually.

[struth]

Acht, just get some classic fullrangers.. then you dont even need digital xovers.:eyebrows:

[Reffc]

Beaming artifacts?

I've also tried Coaxial designs, and come away unsatisfied. I think the real challenge is in getting the HF driver to crossover at a meaningfully low point, or in using a smaller LF driver across the vocal band.

Large LF will "shout" as their directivity narrows with rising frequency.

It is my suspicion that the much appreciated KEF LS50 is an example of a broadband LF driver crossed over high enough that the HF unit can play the rest without distortion or overload.

There's a reason KEF Uni-Q are smaller than classic Tannoy designs.



Sent from my Nexus 6 using Tapatalk

Beaming artifacts?

No. Tannoy DC's have a surprisingly good off axis performance aided by the mid-horn (ie horn plus curved woofer acting as a horn extension) coming in low, in fact they start rolling on below 1KHz. It is untrue to say that they will "shout" as frequency increases, in fact, that has little to do with it, especially on axis! Poorly sorted DC's exhibit horn resonance at around 3KHz and poorly executed DC's which aren't time aligned to begin with (ie most ceramic magnet versions requiring electrical time compensation circuits) exhibit more distortion across the crossover region. Add to this on some larger models cone break up, and collectively, these are more the reasons for the "shoutiness". There are some that honk worse than an angry duck, mostly older Fostec and Lowther designs with whizzer cones. They are truly awful things.

DC's, properly sorted do NOT exhibit "shout". Take the optimally sized 12 inch HPD crossed over at a KHz. Cone resonance isn't anywhere like as pronounced as on large models as the cone is much stiffer. The crossover can be improved and hearing a properly set up pair is a revelation. They neither "shout" nor beam. A read of some of the early technical papers released by Tannoy on the subject of directivity shows that they thought about this aspect and produced something that worked well (Google is your friend). There are far more loudspeakers out there which are way more "beamy" not least older two ways using 12 or 10 inch woofers crossed over at 2 or 3 KHz, creating a large step response. 12 inch DC's do not exhibit a notably large step response in measurement, nor do 10 inch models. 15 inch models do have slightly more, but it is still well within acceptable bounds.

As to producing crossover-less designs, it has been tried with some working better than others but none, not a single one, can be accused of being very accurate because the electro-acoustic reality is that no drive unit has a perfectly flat response and doing away with crossovers completely without time alignment or considering the effects in impedance through the crossover is mostly creating more problems than it solves. Even the so-called "full range" drivers are seldom anything like, and it may come as a surprise that even single drivered designs often require some filtering to keep the acoustic response in check, as again, they do not exhibit an accurate response because of the constraints imposed by physics. Doping a cone has nothing to do with making response accurate, it simply smooths the break-up resonance at the cost of higher compliance, reduced force factor and reduced efficiency. Unless factory applied, it is also very difficult to accurately match two drive units to anything like what we accept as within acceptable tolerance today. Most factory drive units can some off the production line to within 1% of each other. Try doing that with hand doped cones...you can't.

As has been said, active offers may solutions to many practical problems, but it is not the panacea some claim it to be. I have yet to hear a fully active system that I find musical or enjoyable long term. The Adams Audio Column actives came close though. It still requires that an active circuit properly accounts for the acoustic response of each drive unit to correctly re-shape the acoustic profile across the entire bandwidth, not just providing steep crossover slopes and electrical time alignment as most seem to assume. There is no reason why an active system can't be compelling, reasonably accurate, relatively efficient and thoroughly enjoyable. There are enough passive systems floating about in the so-called "high end" spectrum to prove this, as well as some tried and tested designs of yesteryear.

[Ali Tait]

Go fully active with digital crossovers and you side-step all of these problems, and you don't need several grands worth of vintage dual concentric drivers either. I think this will replace the Tannoy hegemony eventually.

Yep, lot to be said for it.

[RothwellAudio]

Add to this on some larger models cone break up, and collectively, these are more the reasons for the "shoutiness". There are some that honk worse than an angry duck, mostly older Fostec and Lowther designs with whizzer cones. They are truly awful things.

My experience of these drivers (admittedly limited) is in total agreement with this.

[Arkless Electronics]

Well, that's a -1 for me. :lol:

I can't stand Tannoy DCs!

+1

[Arkless Electronics]

My experience of these drivers (admittedly limited) is in total agreement with this.

Apart from one particular speaker which did sound very good, all speakers I've heard with lowther drive units have sounded so bad I was left scratching my head and thinking "maybe the owner has severe hearing problems?".... I'm talking worse than the sound from a TV etc!
The one example I heard and found impressive was a large horn system which had something looking like a wooden door knob (phase plug no doubt) at the centre of the obviously much modded Lowther unit. This sounded very good!

[Macca]

Some Lowther drivers do come with the 'door knobs' fitted as standard.

[Reffc]

Some Lowther drivers do come with the 'door knobs' fitted as standard.

and still sound bleeding awful! :lol:

To be fair, if they are bandwidth limited, they make superb midrange units with a little modification. Tommy Horning removes the whizzer cones, and fits a paper-based blanking plug across the gap where the phase plug was (that is also removed) which loads the driver differently, and leaves the HF duties to a bespoke tweeter, just as it should be. They don't sound half bad when used with dedicated woofer and tweeters in a 3-way configuration. He did though drop the idea with the last of the designs, the Agathon Ultimates. The transition from whizzer cone to main cone and back is just too obvious (and painful) and full of audible distortion in the original drive units.

[anji12305]

Beaming artifacts?

No. Tannoy DC's have a surprisingly good off axis performance aided by the mid-horn (ie horn plus curved woofer acting as a horn extension) coming in low, in fact they start rolling on below 1KHz. It is untrue to say that they will "shout" as frequency increases, in fact, that has little to do with it, especially on axis! Poorly sorted DC's exhibit horn resonance at around 3KHz and poorly executed DC's which aren't time aligned to begin with (ie most ceramic magnet versions requiring electrical time compensation circuits) exhibit more distortion across the crossover region. Add to this on some larger models cone break up, and collectively, these are more the reasons for the "shoutiness". There are some that honk worse than an angry duck, mostly older Fostec and Lowther designs with whizzer cones. They are truly awful things.

DC's, properly sorted do NOT exhibit "shout". Take the optimally sized 12 inch HPD crossed over at a KHz. Cone resonance isn't anywhere like as pronounced as on large models as the cone is much stiffer. The crossover can be improved and hearing a properly set up pair is a revelation. They neither "shout" nor beam. A read of some of the early technical papers released by Tannoy on the subject of directivity shows that they thought about this aspect and produced something that worked well (Google is your friend). There are far more loudspeakers out there which are way more "beamy" not least older two ways using 12 or 10 inch woofers crossed over at 2 or 3 KHz, creating a large step response. 12 inch DC's do not exhibit a notably large step response in measurement, nor do 10 inch models. 15 inch models do have slightly more, but it is still well within acceptable bounds.

As to producing crossover-less designs, it has been tried with some working better than others but none, not a single one, can be accused of being very accurate because the electro-acoustic reality is that no drive unit has a perfectly flat response and doing away with crossovers completely without time alignment or considering the effects in impedance through the crossover is mostly creating more problems than it solves. Even the so-called "full range" drivers are seldom anything like, and it may come as a surprise that even single drivered designs often require some filtering to keep the acoustic response in check, as again, they do not exhibit an accurate response because of the constraints imposed by physics. Doping a cone has nothing to do with making response accurate, it simply smooths the break-up resonance at the cost of higher compliance, reduced force factor and reduced efficiency. Unless factory applied, it is also very difficult to accurately match two drive units to anything like what we accept as within acceptable tolerance today. Most factory drive units can some off the production line to within 1% of each other. Try doing that with hand doped cones...you can't.

As has been said, active offers may solutions to many practical problems, but it is not the panacea some claim it to be. I have yet to hear a fully active system that I find musical or enjoyable long term. The Adams Audio Column actives came close though. It still requires that an active circuit properly accounts for the acoustic response of each drive unit to correctly re-shape the acoustic profile across the entire bandwidth, not just providing steep crossover slopes and electrical time alignment as most seem to assume. There is no reason why an active system can't be compelling, reasonably accurate, relatively efficient and thoroughly enjoyable. There are enough passive systems floating about in the so-called "high end" spectrum to prove this, as well as some tried and tested designs of yesteryear.
Setting the crossover point below 2k will hand off between the drivers in the range where human hearing is most sensitive.

The current vogue in compression driver designs is a response to this, lowering the crossover point below 700Hz. Troels Gravensen's excellent JA8008 midrange driver is an alternative, covering a broader range to raise the crossover point above 2kHz.





Apart from one particular speaker which did sound very good, all speakers I've heard with lowther drive units have sounded so bad I was left scratching my head and thinking "maybe the owner has severe hearing problems?".... I'm talking worse than the sound from a TV etc!
The one example I heard and found impressive was a large horn system which had something looking like a wooden door knob (phase plug no doubt) at the centre of the obviously much modded Lowther unit. This sounded very good!


Sent from my Nexus 6 using Tapatalk

[danilo]

Go fully active with digital crossovers and you side-step all of these problems, and you don't need several grands worth of vintage dual concentric drivers either. I think this will replace the Tannoy hegemony eventually.

Perhaps consider Line level crossovers for Tannoy DC's :eyebrows:
Either Active (powered ) or Passive ( unpowered)
Audible upgrade over the typ Tannoy crossover circuit, regardless of provenance ;)
DSP may work too. Dunno tho, as I haven't personally tried that... although I have heard the wee background noises that DSP often injects.

Genuine caveat though: with line level crossovers.. one needs a pair of *Identical* amps.
Some claim otherwise. However I found unmatched amps to be annoying / problematic, seriously so actually.
Currently working on aquiring a Second F6.. mebe next spring.

[Reffc]

Setting the crossover point below 2k will hand off between the drivers in the range where human hearing is most sensitive.

The current vogue in compression driver designs is a response to this, lowering the crossover point below 700Hz. Troels Gravensen's excellent JA8008 midrange driver is an alternative, covering a broader range to raise the crossover point above 2kHz.







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And the old chestnut that this is always audible is just that...an old chestnut. Well designed crossovers with well matched drivers, with decent time alignment and on axis at any rate, the crossover most certainly does not have to be audible, that's just another a forum-land myth. Poor designs are. Good designs are not. For the record, Troels designs for DC's is both incorrect and based on acoustic response from a damaged drive unit. The circuit ought to have been taken down years ago. You obviously do not understand Tannoy DC's if you think that it's a good idea to introduce a mid range drive unit to them. They already have a mid function by dint of the main cone being used as an extension of the main horn to cover the midrange. ;)

Active crossovers can work with Tannoys. I've heard one but wasn't blown away. Earlier AlNiCo units (time aligned and phase correct) imho were, and remain better using passive solutions. Later K series benefit from active crossovers far more to tackle the highly audible time compensation area (at least it remains audible in passive guise).

[anthonyTD]

:)
Beaming artifacts?

No. Tannoy DC's have a surprisingly good off axis performance aided by the mid-horn (ie horn plus curved woofer acting as a horn extension) coming in low, in fact they start rolling on below 1KHz. It is untrue to say that they will "shout" as frequency increases, in fact, that has little to do with it, especially on axis! Poorly sorted DC's exhibit horn resonance at around 3KHz and poorly executed DC's which aren't time aligned to begin with (ie most ceramic magnet versions requiring electrical time compensation circuits) exhibit more distortion across the crossover region. Add to this on some larger models cone break up, and collectively, these are more the reasons for the "shoutiness". There are some that honk worse than an angry duck, mostly older Fostec and Lowther designs with whizzer cones. They are truly awful things.

DC's, properly sorted do NOT exhibit "shout". Take the optimally sized 12 inch HPD crossed over at a KHz. Cone resonance isn't anywhere like as pronounced as on large models as the cone is much stiffer. The crossover can be improved and hearing a properly set up pair is a revelation. They neither "shout" nor beam. A read of some of the early technical papers released by Tannoy on the subject of directivity shows that they thought about this aspect and produced something that worked well (Google is your friend). There are far more loudspeakers out there which are way more "beamy" not least older two ways using 12 or 10 inch woofers crossed over at 2 or 3 KHz, creating a large step response. 12 inch DC's do not exhibit a notably large step response in measurement, nor do 10 inch models. 15 inch models do have slightly more, but it is still well within acceptable bounds.

As to producing crossover-less designs, it has been tried with some working better than others but none, not a single one, can be accused of being very accurate because the electro-acoustic reality is that no drive unit has a perfectly flat response and doing away with crossovers completely without time alignment or considering the effects in impedance through the crossover is mostly creating more problems than it solves. Even the so-called "full range" drivers are seldom anything like, and it may come as a surprise that even single drivered designs often require some filtering to keep the acoustic response in check, as again, they do not exhibit an accurate response because of the constraints imposed by physics. Doping a cone has nothing to do with making response accurate, it simply smooths the break-up resonance at the cost of higher compliance, reduced force factor and reduced efficiency. Unless factory applied, it is also very difficult to accurately match two drive units to anything like what we accept as within acceptable tolerance today. Most factory drive units can some off the production line to within 1% of each other. Try doing that with hand doped cones...you can't.

As has been said, active offers may solutions to many practical problems, but it is not the panacea some claim it to be. I have yet to hear a fully active system that I find musical or enjoyable long term. The Adams Audio Column actives came close though. It still requires that an active circuit properly accounts for the acoustic response of each drive unit to correctly re-shape the acoustic profile across the entire bandwidth, not just providing steep crossover slopes and electrical time alignment as most seem to assume. There is no reason why an active system can't be compelling, reasonably accurate, relatively efficient and thoroughly enjoyable. There are enough passive systems floating about in the so-called "high end" spectrum to prove this, as well as some tried and tested designs of yesteryear.

[anthonyTD]

Quite agree, and I have owned some in the past!
Apart from one particular speaker which did sound very good, all speakers I've heard with lowther drive units have sounded so bad I was left scratching my head and thinking "maybe the owner has severe hearing problems?".... I'm talking worse than the sound from a TV etc!

[docfoster]

And the old chestnut that this is always audible is just that...an old chestnut. Well designed crossovers with well matched drivers, with decent time alignment and on axis at any rate, the crossover most certainly does not have to be audible, that's just another a forum-land myth. Poor designs are. Good designs are not.

As you know Paul, I know nothing of the technical stuff, but based on my limited experience listening to various design approaches. I feel that this statement has legs.
I once owned some NVA Cube 1 speakers, which are a non-crossover design. I very much liked them. They sounded immediate and natural. I assume that their lack of crossover played some part in this. In fact, I liked them so much that they replaced a pair of Dynaudio Audience 82s that were in my system at the time.
Then, I got hold of a pair of big old Goodmans Goodwoods. They sounded to me not as good as the NVAs or the Dynaudios. Nowhere near in fact. However, it must be said that the Goodmans were not in the rudest of health...
Paul, you'll remember that you took the Goodmans under your wing and performed various procedures on them, including rebuilding the crossovers from scratch, using a nice balance of measurement, knowledge and careful listening. When they returned from your place the Goodmans were to my ears, the most pleasing speakers that I've ever had in my system. They've stayed put ever since. No idea what bits of your work resulted in which aspects of the Goodmans renaissance, but I've presumed that the attention you paid to bespoking the crossover for the Goodmans particular cabinet and drivers was some part of their now very neurtal (in frequency response and dynamics) sound.
As you say, a poorly designed crossover may well sound worse than no crossover (almost by definition I suppose), but maybe it is possible to design a good crossover that is better than no crossover.
As I say, I have absolutely no techincal knowledge, just reporting what my ears tell me, like.

[anji12305]

And the old chestnut that this is always audible is just that...an old chestnut. Well designed crossovers with well matched drivers, with decent time alignment and on axis at any rate, the crossover most certainly does not have to be audible, that's just another a forum-land myth. Poor designs are. Good designs are not. For the record, Troels designs for DC's is both incorrect and based on acoustic response from a damaged drive unit. The circuit ought to have been taken down years ago. You obviously do not understand Tannoy DC's if you think that it's a good idea to introduce a mid range drive unit to them. They already have a mid function by dint of the main cone being used as an extension of the main horn to cover the midrange. ;)

Active crossovers can work with Tannoys. I've heard one but wasn't blown away. Earlier AlNiCo units (time aligned and phase correct) imho were, and remain better using passive solutions. Later K series benefit from active crossovers far more to tackle the highly audible time compensation area (at least it remains audible in passive guise).
Forum land myth?

Which loudspeaker are you selling professionally? If none, what are your qualifications for blanket condemnation?

Perhaps you can produce credentials to validate your position. That, I doubt.

"The range of human hearing is generally considered to be 20 Hz to 20 kHz, but it is far more sensitive to sounds between 1 kHz and 4 kHz. For example, listeners can detect sounds as low as 0 dB SPL at 3 kHz, but require 40 dB SPL at 100 hertz (an amplitude increase of 100). Listeners can tell that two tones are different if their frequencies differ by more than about 0.3% at 3 kHz. This increases to 3% at 100 hertz. For comparison, adjacent keys on a piano differ by about 6% in frequency."

http://www.dspguide.com/ch22/1.htm



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[Macca]

Forum land myth?

Which loudspeaker are you selling professionally? If none, what are your qualifications for blanket condemnation?

Perhaps you can produce credentials to validate your position. That, I doubt.

"The range of human hearing is generally considered to be 20 Hz to 20 kHz, but it is far more sensitive to sounds between 1 kHz and 4 kHz. For example, listeners can detect sounds as low as 0 dB SPL at 3 kHz, but require 40 dB SPL at 100 hertz (an amplitude increase of 100). Listeners can tell that two tones are different if their frequencies differ by more than about 0.3% at 3 kHz. This increases to 3% at 100 hertz. For comparison, adjacent keys on a piano differ by about 6% in frequency."

http://www.dspguide.com/ch22/1.htm



Sent from my Nexus 6 using Tapatalk

Paul does design and sell speakers professionally, and he is qualified to talk about it, so I'm not sure why you seem so convinced that he isn't?

In any case it needs to be borne in mind that there are many different ways to skin he cat when it comes to speakers, and perfect technical performance is as nothing if the speakers do not 'do it' for you. Given that no speaker is perfect, talk of the 'right' and 'wrong' way of doing things is a little pointless.

The design philosophy is not important, what is important is ensuring the optimum implementation of design philosophy you choose.

[Arkless Electronics]

The comparative lack of popularity of active speakers in hi fi circles is I think something where we may see some change in the future... or maybe not! They have been de rigeur in professional circles for years and (some will disagree but my own view is set in stone) are superior in every way to passive speakers. I guess the extra technical complexity combined with it being much more difficult to box swap and "fart about" with puts many off...

[Reffc]

Forum land myth?

Which loudspeaker are you selling professionally? If none, what are your qualifications for blanket condemnation?

Perhaps you can produce credentials to validate your position. That, I doubt.

"The range of human hearing is generally considered to be 20 Hz to 20 kHz, but it is far more sensitive to sounds between 1 kHz and 4 kHz. For example, listeners can detect sounds as low as 0 dB SPL at 3 kHz, but require 40 dB SPL at 100 hertz (an amplitude increase of 100). Listeners can tell that two tones are different if their frequencies differ by more than about 0.3% at 3 kHz. This increases to 3% at 100 hertz. For comparison, adjacent keys on a piano differ by about 6% in frequency."

http://www.dspguide.com/ch22/1.htm



Sent from my Nexus 6 using Tapatalk


Your response has to rank as one of the most arrogant and rude on AoS in recent months, well done! :lol:

I design loudspeakers for other manufacturers (who by virtue of the commercial sensitivity of the agreements, cannot be named) as well as a list of bespoke designs (including the RFC Canterbury, Warwick, Fidelio, Raptor and Rhapsody). However, I do not answer to you, and clearly, you need to brush up a little on your own knowledge...and manners.

[Firebottle]

:clapclapclap:

:)

[Pieoftheday]

Well I'm certainly glad I asked the question,i have very little ,if any technical knowledge about such things but I'm always impressed by the knowledge some of you have.if I've learnt one thing from this post, designing speakers ain't simple!!!

[walpurgis]

Forum land myth?

Never mind having a dig at one of our respected trade contributors.

Who are you? Looks like you've only been with us a very short while and seemingly did not bother to introduce yourself in the 'Welcome' area as is the norm when joining, so we know nothing about you. I suggest you might address this before proceeding further here.

And a more polite and diplomatic approach won't hurt either!

[loveoscar]

Your response has to rank as one of the most arrogant and rude on AoS in recent months, well done! :lol:

I design loudspeakers for other manufacturers (who by virtue of the commercial sensitivity of the agreements, cannot be named) as well as a list of bespoke designs (including the RFC Canterbury, Warwick, Fidelio, Raptor and Rhapsody). However, I do not answer to you, and clearly, you need to brush up a little on your own knowledge...and manners.

Perhaps you'll have to put one of your speaker designs/mods up for a bake off sometime, this will of course prove your knowledge.

[Pieoftheday]

Perhaps you'll have to put one of your speaker designs/mods up for a bake off sometime, this will of course prove your knowledge.
:doh:

[Reffc]

Perhaps you'll have to put one of your speaker designs/mods up for a bake off sometime, this will of course prove your knowledge.

I have had many bake offs here over the years and the speakers have fared very well thank you. You are of course more than welcome to listen any time you're in the area and experience for yourself. Please PM me if you'd like to make those arrangements. You are also more than welcome to request feedback from those who've listened to them. Why some AoS members find it so necessary to be so derogatory, I don't know. As a trade member who consistently tries to contribute in a positive manner, I may as well not bother. In fact, I am now seriously starting to question whether I want any further part in forums at all.

[Gordon Steadman]

Don't be daft. You can't let a few trolls or the odd doubting Thomas drive you away.

The decision should be about enjoyment/commercial worth/ communication. If that makes it not worth it fine. There are all sorts of opinions, some treated as fact, and only those that actually do things have a right to those opinions when it comes to technical matters. All else is received wisdom and discountable by anyone sensible.

What we hear is a different matter but that isn't what is being discussed here.

[Arkless Electronics]

Don't be daft. You can't let a few trolls or the odd doubting Thomas drive you away.

The decision should be about enjoyment/commercial worth/ communication. If that makes it not worth it fine. There are all sorts of opinions, some treated as fact, and only those that actually do things have a right to those opinions when it comes to technical matters. All else is received wisdom and discountable by anyone sensible.

What we hear is a different matter but that isn't what is being discussed here.

+1

I've put up with worse, sometimes thrown it back, sometimes ignored it.... sometimes got provoked into going too far! There are idiots out there who think you can't be any good if they've not heard of you unfortunately:steam:

We all appreciate your words of wisdom on speaker design Paul and it would be a great loss to the site for someone like yourself to leave over the petty remarks of an ejit!

[Marco]

Perhaps you'll have to put one of your speaker designs/mods up for a bake off sometime, this will of course prove your knowledge.

David, Paul doesn't have to prove anything to anyone here. You're new to the forum (and welcome, btw), but I suggest that you wind your neck in a little before steaming in and challenging established members in such an aggressive manner - that is if you wish to remain here for any length of time.

So, chill out and get a feel for the place properly before you end up doing something you might regret. Cheers! :cool:

Marco.

[Marco]

That also applies to you, Anji. Guys, it's very easy just to hit the ban button, and save all of us a whole load of grief, so don't make me do that. These days, we operate a zero-tolerance policy on irritants/trolls, so if you're here just to cause aggro, you won't be here for long.

Marco.

[Pieoftheday]

+1

I've put up with worse, sometimes thrown it back, sometimes ignored it.... sometimes got provoked into going too far! There are idiots out there who think you can't be any good if they've not heard of you unfortunately:steam:

We all appreciate your words of wisdom on speaker design Paul and it would be a great loss to the site for someone like yourself to leave over the petty remarks of an ejit!

+2, just chuckle at em, knobeads are far n few between on here

[loveoscar]

I have had many bake offs here over the years and the speakers have fared very well thank you. You are of course more than welcome to listen any time you're in the area and experience for yourself. Please PM me if you'd like to make those arrangements. You are also more than welcome to request feedback from those who've listened to them. Why some AoS members find it so necessary to be so derogatory, I don't know. As a trade member who consistently tries to contribute in a positive manner, I may as well not bother. In fact, I am now seriously starting to question whether I want any further part in forums at all.

My quote was not supposed to be derogatory, quite the opposite, its just that since I've be looking at the Aos site I never see your speakers at any bakeoffs/Nebo/Mibo. I would have thought getting your products 'out there' would be a good thing. This has nothing to do with advice you kindly give to the members on here.

[walpurgis]

I know it's your first day with us Dave and I think your post could have been better put. But if as you say you meant no offence, maybe none should be taken. Paul (RFC) does not need to be 'out there' as much as some. His trade credentials are well established. Forum bake offs are not necessarily the best place for trade displays anyway.

[Radford Revival]

For what it's worth I've heard all of Paul's major speaker incarnations from his Tannoys and two-day designs and they are all excellent sounding. I in fact own a pair of his Raptors and I know the countless crossover revisions he went through, which he then rejected as they weren't up to his standard. Then he scrapped the first crossover architecture entirely to try a different road with simulation, which yielded a simpler but better measuring crossover. Not stopping there, he then tweaked that to get the subjective tonal balance just right. The integration between the drivers is seamless.

I talk to Paul a lot and I know the sheer amount of effort he goes to with ALL of his speakers, not just his main models but his repairs, bespoke designs and crossovers too, he will go the extra mile to get something done right and will work for entire extra days beyond the original quote/plan/intention, in the name of doing a good job. I've seen him agonise over the finish of his Tannoy models and even helped him apply goodness knows how many layers (and almost pass out from fumes) of various types of finish even when there were cheaper methods to achieve a similar but ultimately not as good result.

Paul's good rep was entirely earned through sheer hard work.

[montesquieu]

For what it's worth I've heard all of Paul's major speaker incarnations from his Tannoys and two-day designs and they are all excellent sounding. I in fact own a pair of his Raptors and I know the countless crossover revisions he went through, which he then rejected as they weren't up to his standard. Then he scrapped the first crossover architecture entirely to try a different road with simulation, which yielded a simpler but better measuring crossover. Not stopping there, he then tweaked that to get the subjective tonal balance just right. The integration between the drivers is seamless.

I talk to Paul a lot and I know the sheer amount of effort he goes to with ALL of his speakers, not just his main models but his repairs, bespoke designs and crossovers too, he will go the extra mile to get something done right and will work for entire extra days beyond the original quote/plan/intention, in the name of doing a good job. I've seen him agonise over the finish of his Tannoy models and even helped him apply goodness knows how many layers (and almost pass out from fumes) of various types of finish even when there were cheaper methods to achieve a similar but ultimately not as good result.

Paul's good rep was entirely earned through sheer hard work.

Well said Will. Paul has nothing to prove here.

We do seem to be having a rash of obvioxious trolling lately, all strangely enough appearing to come from North America .. though I personally suspect it more likely that some otherwise banned-everywhere troublemakers closer to home (we all know who they are) might might have discovered the trick of using a foreign proxy server ...

[Marco]

If that's the case, Tom, they'll be sent packing as quickly as they arrived... As I said, these days we don't piss around trying to 'appease' folk who're here just to be a PITA - they're just booted, as we can't be arsed with the grief!

Therefore, it's up to the new members concerned to prove themselves and to contribute constructively to the forum and fit in, without making waves, if they wish to remain here. It's as simple as that.

Marco.

[loveoscar]

:
I know it's your first day with us Dave and I think your post could have been better put. But if as you say you meant no offence, maybe none should be taken. Paul (RFC) does not need to be 'out there' as much as some. His trade credentials are well established. Forum bake offs are not necessarily the best place for trade displays anyway.

Thanks for a little support there Walpurgis, but I thought bake offs were there for everyone to hear whats good, bad or indifferent. The more good products out there the better for all hifi enthusiasts. How many members on here have actually heard Pauls designs, I for one have not unless its from a manufacture who must remain nameless. :)

[montesquieu]

:

Thanks for a little support there Walpurgis, but I thought bake offs were there for everyone to hear whats good, bad or indifferent. The more good products out there the better for all hifi enthusiasts. How many members on here have actually heard Pauls designs, I for one have not unless its from a manufacture who must remain nameless. :)

Well Mr New Person with 10 posts who seems mysteriously to be a veteran of bake-offs... if you WERE genuinely an expert on bake-offs you would know that the kit that usually doesn't travel to bake-offs is speakers (unless they are of the small stand mount variety which not many of us have, funnily enough, in our main systems) ... I have a pair of RFC Canterburys (Paul's design) and it took a Luton van to move them and 3 people to lift them into the house (via the French windows at the back). It's not like chucking a preamp or phono stage in the boot you know.

[anthonyTD]

+2
+1

I've put up with worse, sometimes thrown it back, sometimes ignored it.... sometimes got provoked into going too far! There are idiots out there who think you can't be any good if they've not heard of you unfortunately:steam:

We all appreciate your words of wisdom on speaker design Paul and it would be a great loss to the site for someone like yourself to leave over the petty remarks of an ejit!

[loveoscar]

Well Mr New Person with 10 posts who seems mysteriously to be a veteran of bake-offs... if you WERE genuinely an expert on bake-offs you would know that the kit that usually doesn't travel to bake-offs is speakers (unless they are of the small stand mount variety which not many of us have, funnily enough, in our main systems) ... I have a pair of RFC Canterburys (Paul's design) and it took a Luton van to move them and 3 people to lift them into the house (via the French windows at the back). It's not like chucking a preamp or phono stage in the boot you know.

I really don't know why I am being attacked here. Were in my post do I say I am a veteran of bake offs. I can fully understand large speakers are never easy to move and best left at home. Are all of Paul designs of this size? I have re read all my posts on this thread and non of them to me have been insulting to Paul.:scratch: I believe if you've got a good product go out there and show others.

[walpurgis]

This 'discussion' is going nowhere useful, and is adding nothing to the original topic, so perhaps it's best left there and all concerned move on.

[Macca]

I really don't know why I am being attacked here. Were in my post do I say I am a veteran of bake offs. I can fully understand large speakers are never easy to move and best left at home. Are all of Paul designs of this size? I have re read all my posts on this thread and non of them to me have been insulting to Paul.:scratch: I believe if you've got a good product go out there and show others.

You did post this to Paul:

Perhaps you'll have to put one of your speaker designs/mods up for a bake off sometime, this will of course prove your knowledge.

Which is akin to telling Lewis Hamilton that if he thinks he is such a good driver perhaps he should enter a race sometime.

[Hudz]

I have had many bake offs here over the years and the speakers have fared very well thank you. You are of course more than welcome to listen any time you're in the area and experience for yourself. Please PM me if you'd like to make those arrangements. You are also more than welcome to request feedback from those who've listened to them. Why some AoS members find it so necessary to be so derogatory, I don't know. As a trade member who consistently tries to contribute in a positive manner, I may as well not bother. In fact, I am now seriously starting to question whether I want any further part in forums at all.

Don't let the bastards grind you down Paul, I for one will always be deeply grateful for the work you did on my Heybrooks and for imparting a share of your wealth of knowledge.

This forum will be a much poorer place without the likes of you, Jez, Will at Radford, Firebottle and all the other professionals who contribute regularly and share their knowledge freely.

[loveoscar]

You did post this to Paul:

Perhaps you'll have to put one of your speaker designs/mods up for a bake off sometime, this will of course prove your knowledge.

Which is akin to telling Lewis Hamilton that if he thinks he is such a good driver perhaps he should enter a race sometime.

Don't forget this was in reply to Paul's response were he used the word knowledge, and that is why I did in my reply. Lets not forget we can see Lewis Hamilton's skills on the race track on tv, the point I have been making is we don't see or hear Paul's abilities openly at shows or bake offs. I guess all this bad feeling against me stems from a previous post from someone USA based, although I for one did not find that offensive, maybe a little blunt but I'll leave that for people with greater electronics knowledge than me to point out any errors he made.

[Macca]

David, I guess it is not your fault that you were unaware of Paul's track record.

There is no bad feeling against you, however I think the general feeling is that the 'post from someone in the USA' was out of order.

As far as shows go, a number of manufacturers are on record as saying they do little to generate sales, so a lot of the smaller concerns do not bother with them due to the hassle and the expense. Paul has in the past hosted and attended bake-offs with his speakers, plus you can also make an appointment with him to go to his place and hear the RFC Canterbury and other RFC designs for yourself, should you so wish.

As pointed out previously, these are very large and heavy speakers, not something you can just chuck in the boot of an average vehicle and take anywhere without a lot of planning and effort.

[montesquieu]

Don't forget this was in reply to Paul's response were he used the word knowledge, and that is why I did in my reply. Lets not forget we can see Lewis Hamilton's skills on the race track on tv, the point I have been making is we don't see or hear Paul's abilities openly at shows or bake offs. I guess all this bad feeling against me stems from a previous post from someone USA based, although I for one did not find that offensive, maybe a little blunt but I'll leave that for people with greater electronics knowledge than me to point out any errors he made.

There is a question of tone. I know what I would expect if I turned up new on a forum and started having a go at people who have spent years contributing and with whom many have had very positive personal contact. I suggest you attempt to earn your stripes here with your own positive contribution before you start questioning anyone's credentials - as you have found out anything else is likely to get short shrift.

[Marco]

There is a question of tone. I know what I would expect if I turned up new on a forum and started having a go at people who have spent years contributing and with whom many have had very positive personal contact. I suggest you attempt to earn your stripes here with your own positive contribution before you start questioning anyone's credentials - as you have found out anything else is likely to get short shrift.

^This in a nutshell^ The whole post, not just the bit in bold... However, tone/emotion can be difficult to convey accurately when the written word is all you have to use.

David, overall you're doing ok so far, however, let me ask you this:

Are you the sort of person that when walking into a pub (not your local), you go straight up to the bar, sit down on a stool, and whilst ordering a pint immediately start criticising one of the regulars there for his dress sense, or would you order your pint as unobtrusively as possible and take it quietly over to the corner of the bar and sit down, without feeling the need to 'get noticed'?

If you want to become a regular in a pub and accepted by the regulars, slowing integrating yourself is usually the best way, than to steam in like a bull in a china shop... Some folk in life, I've found, love the sound of their own voice too much for their own good. I do hope you can see where I'm coming from without taking offence :)

Marco.

[loveoscar]

I would certainly not go into a pub or anywhere else an immediately insult anyone, maybe pull their leg and have a joke. Please point out in any of my post were I have insulted anyone. As far as I am concerned my comments on Paul getting his products out there is good advice. I asked how many members have heard his speakers/mods, so far 2 members have come forward. I can understand that large speakers are almost impossible to transport to bake offs, I did not realise all his speakers were of this size.

[Macca]

I have also heard Paul's speakers. In fact his whole system. I don't think he makes smaller speakers any more except to order, but when he did I recall him taking them to several bake offs and possibly a show or two. Nowadays he is the go to man for Tannoy DC related stuff on both sides of the Atlantic.

[struth]

One of the nicest guys in the business too

[Marco]

I would certainly not go into a pub or anywhere else an immediately insult anyone, maybe pull their leg and have a joke. Please point out in any of my post were I have insulted anyone.

Not so much insult anyone, David, but be somewhat too forthright and imprudent considering you're new to the AoS community, which I liken to that of a good local pub. That's the sort of vibe we aim for here. I may be wrong and only going by initial impressions, but you strike me as someone who would be more at home sitting in front of the bar, than at a table in the corner....

Anyway, it's fine. Your most recent posts are more encouraging than your rather less than auspicious entrance to the forum. Long may that continue! :cool:

Marco.

[loveoscar]

There you go then, we now know Paul is the go to man for Tannoy DC's and he's one of the nicest blokes in the business. All this from a small post by me which was meant to be helpful.:lol: Insults to anyone - please point them out to me.

[Macca]

You did post this to Paul:

Perhaps you'll have to put one of your speaker designs/mods up for a bake off sometime, this will of course prove your knowledge.

Which is akin to telling Lewis Hamilton that if he thinks he is such a good driver perhaps he should enter a race sometime.

Not an insult but as I said...

[anji12305]

That also applies to you, Anji. Guys, it's very easy just to hit the ban button, and save all of us a whole load of grief, so don't make me do that. These days, we operate a zero-tolerance policy on irritants/trolls, so if you're here just to cause aggro, you won't be here for long.

Marco.
Hardly the case. We have similar broad pronouncements from those retrofitting ancient Klipsch speakers for fun and profit.

Those fanboys don't much care to have the sceptical asking for verifiable evidence, either.

Methinks your man does protest too much.

Have fun storming the castle.

Sent from my Nexus 6 using Tapatalk

[Macca]

Hardly the case. We have similar broad pronouncements from those retrofitting ancient Klipsch speakers for fun and profit.

Those fanboys don't much care to have the sceptical asking for verifiable evidence, either.

Methinks your man does protest too much.

Have fun storming the castle.

Sent from my Nexus 6 using Tapatalk

So you want to be banned then? What exactly was the point in joining in the first place? Have fun acting like a prick somewhere else.

[Marco]

Bye bye "anji" :wave: :wave:

Marco.

[loveoscar]

Seems a touch harsh since no one disagreed with the facts stated in his post. His posting style maybe blunt, but try to keep an open mind on a public forum. I've just had this problem, but it does not mean I cannot add to the forum and also learn. :)

[Marco]

Stick to commenting on hi-fi and music, David, and out of forum politics, unless you wish to go the same way. Some folk just don't fit in, especially those who refuse to respect our ethos. The decision isn't up for debate, so any further 'chat' on the matter will result in it being deleted and you being given a week's holiday.

Now, back to the thread topic, please!

Marco.

[Reffc]

Thank you to all who have provided kind words of support. Yes, there are always a small handful of internet trolls who try and spoil it for many, or single out an individual for their dubious agendas filled with vitriol and spite. Orchestrated trolling by puppets possibly throwing mud pies not of their own making but happy to take part in such destructive unpleasantness as if creating bad feeling is a trophy to be proud of. Sad little people.

Back on topic, if, David, you are asking for something more independent, then the following review ties in nicely with the topic as it is one example of a speaker designed to offer an amp-easy load. I refer to the Reference Raptor design which Will from Radford owns. The design is owned by a few individuals including one of Harry Christophers The Sixteen, a chap who needs no lecturing or tutoring in music and musical excellence. Anyway,here's an independent review for which a fully independent audio consultant, one of he UK's most respected, undertook all the measurement:

http://www.dagogo.com/reference-fidelity-components-raptor-speakers-review/3

Here's a snip of the impedance plot with frequency:

http://i1140.photobucket.com/albums/n577/24pacman/RFC%20Cables/Reference%20raptor%20Impedance%20curve_zpsaqdw5gio .jpg

You can see from this image, that these represent a very easy load with a genuine 6 Ohm load...no dipping of impedance and no ultra-steep ultra-deep phase swings in the bass region. Whilst such a design benefits from a little more juice that a more sensitive and efficient Tannoy DC design, it remains a genuinely benign load for most amplifiers. Sadly, few loudspeaker manufacturers choose to publish their impedance curves which is a shame as it does help when matching to an amplifier. Speaker impedance though is easy enough to measure these days with the right kit.

As to why small companies are not in the mainstream David, the answer is that we're not massive conglomerates requiring lions shares of the hifi pie. Companies like Radford, myself, Jez (Arkless), Tube Distinctions, Longdog Audio, TRON and others all specialise in certain areas, are all qualified engineers with extensive experience of design and manufacture, and have no need or desire to chase volume sales. I mainly provide custom builds and have no intention, none whatsoever of stacking them high and selling them cheap. I don't do this for massive profit and growth, I do it because I love what I do, try to do it well and try to look after my customers well. If it brings others happiness, that is a worthy goal. It is not a job interview demanding a CV nor requiring any sort of justification. Those that "know their stuff" in the hifi world know that, and as a small world (at least in the UK) many of the smaller talented outfits and audio engineers all know one-another, although not all post on forums. Enough of that for now. If you want to take this further as a chat, you are perfectly free to contact me as you are any other trade member.

[struth]

Testing

[Marco]

Thank you to all who have provided kind words of support. Yes, there are alwyas a small handful of internet trolls who try and spoil it for many, or single out an individual for their dubious agendas filled with vitriol and spite. Orchestrated trolling by puppets possibly throwing mud pies not of their won making but happy to take part in such destructive unpleasnatness as if creating bad feeling is a trphy to be proud of. Sad little people.


Indeed. You have to remember that these 'entities' don't have a life, and are nothing but jealous and deeply unhappy [even if they won't admit it to themselves] downtrodden, unfulfilled inadequates, angry with the world and all those who inhabit it, who unlike them, are successful, happy and contented with theirs, so the only 'joy' they can extract from their (largely) empty existence is to try and bring the likes of you and I down to their pitifully sad level.

Essentially, they have serious self-esteem issues... Shame, but inadequates often do.

Rise above it, mate, and treat them with the contempt that they deserve, by ignoring them and thus rendering their 'status' to that of total irrelevance, or surreptitiously rub their noses in their obvious unhappiness [hate their job, hate their private life, dread getting up in the morning, haha too bad] and thus sense of frustration and failure, for your own amusement.

That's what I do with a BIG smile on my face because I know it irks them, and they hate it - and if they hate it and it piles some [highly deserved] misery on them, I love it! ;)

There's a well-known such entity elsewhere, called 'alfer', and he doesn't realise that he's simply my pet toy.

Marco.

[RothwellAudio]

Back to the original topic - if anyone is still interested :scratch: - I've stumbled upon this:
http://www.audiomisc.co.uk/HFN/SCAMP/scamp.html
It's a bit technical and quite heavy going to read but is very thorough and tells you everything you need to know (probably).

[Arkless Electronics]

KEF used to use their "Conjugate Load Matching" technique on their top of the range models for several years, which was a very good idea! My own Reference 105.3's where I believe one of the last to use it... A KEF engineer told me that it was expensive to do and went above most potential purchasers heads and hence was not a sales boosting feature for them (the old, old story...) and it was abandoned when the "Reference 4" etc replaced the Reference 105.3 and Reference 107 etc

[Reffc]

Back to the original topic - if anyone is still interested :scratch: - I've stumbled upon this:
http://www.audiomisc.co.uk/HFN/SCAMP/scamp.html
It's a bit technical and quite heavy going to read but is very thorough and tells you everything you need to know (probably).

Indeed Andrew, and it goes some way to explaining just why many people may be running their amplifiers into clipping without realising it or over-straining them due to insufficient dissipation. The minimum impedance or quoted nominal impedance often quoted for loudspeaker specifications tells the customer very little in reality. It's usually advisable to match an amplifier capable of delivering sufficient current well over what might be calculated from impedance figures alone and one that can deal with phase angle swings fairly rapidly.