Looking for advice on attenuation

[upperholme]

I understand its a very common issue, and yet i haven't come across much in the way of coverage or discussion about how best to address it:

At normal listening levels, whether the source be vinyl, CD player, Mac or even tuner, I rarely get the volume control on my little amp past 8 o'clock. What I read is that this is because the output from the source kit is essentially higher than the amp was originally designed to cope with.

The only solutions that I've come across thus far - barring ignoring the whole issue - are to use Rothwell attenuators, lash out on expensive Russ Andrews attenuating interconnects, or use a passive preamp like the little Tisbury Audio unit that provides switchable attenuation.

What makes me think that ignoring the problem is not the way to go is my sense that by running my amp in this way I'm not getting the best from it, and that it would give a better result if i could get the volume pot up somewhere in the 10 o'clock - 2 o'clock zone. Of course I may well be talking rot.

What have others got to say on this issue?

All the best
Graham

[realysm42]

Discounting every other factor, it's good to have more usable range on the volume dial. I used to have the same 'issue' as you; I basically had between silent and speaker damaging from 8 to 12 o'clock.

If you're not going to buy new equipment then attenuators are a good way to go. Another option is if you're going to stick with what you've got for a while you can get the gain of your amp changed, but this can be expensive and let's be honest, gear tends not to stick about forever and any mods you do will only hurt resale value.

Take this next bit with a pinch of salt but in my experience adding a TVC preamp to the mix has opened up a much larger range of usable volume for me. Having said that I use Dirac (Digital Room Correction) which (optionally) cuts off 8db from source (PC in my case) volume. So I'd lose a fair bit again if this wasn't in use.

Getting lower sensitivity speakers will open up range as they will kind of act like built in attenuation.

As with all things in this hobby, having a clear idea of where you want to be will inform your decision making and allow you to be strategic in your decision making (like any well scoped/good project really).

[Mr. C]

I have yet to hear any plug in attenuators even when using ultra transparent resistors not have a detrimental sound effect.

[The Black Adder]

+1 - I've had Rothwells, Golden Jacks and another make I can't remember.. All do the job but cloud the sound somewhat.

Best thing to do is to get the gain sorted internally.

[upperholme]

I'll certainly experiment with swapping out the speakers to see what impact that might have. Thanks for the tip. I'm loathe to get the amp modified as I'm aiming to replace it in the not too distant future.

[upperholme]

Thanks all for the prompt feedback. I had read that Rothwell (and other) plug-in attenuators can have a negative impact on sound quality, and your comments confirm that, so I'll not be going down that road.
I'm thinking I might give the Tisbury a spin. As I'm working up to replacing the amp in the course of the next year or so, and moving from an integrated amp to a pre/power approach, this would also make some sense in that context.

[hifi_dave]

Try the Rothwells and if you can hear any degredation, then return them. They are by far the cheapest option.

[Macca]

Where the volume pot is pointing to on the dial won't make any difference to sound quality, so I wouldn't worry about that side of it.

If you have a situation where you cannot get the volume right - a choice between either too quiet or blasting out - that is a pain in the arse as I know from experience. I don't like in-line attunators for the same reason folk have outlined above, but a passive pre-amp would sort the issue out.

[walpurgis]

I have used Rothwell attenuators and whist their audible effect is noticeable, it is pretty minimal. About as much as can sometimes be heard after a cable change.

[struth]

I,d agree.. Its not un noticible either , but there are handy for checking if youve a problem with gain

[upperholme]

Try the Rothwells and if you can hear any degredation, then return them. They are by far the cheapest option.

They would be the cheapest option if I only needed one pair. With three sources I'd need a pair for each source as I understand it, which adds up roughly what I'd pay for the Tisbury pre, and they wouldn't offer the same level of flexibility/control. :-(

[upperholme]

Where the volume pot is pointing to on the dial won't make any difference to sound quality, so I wouldn't worry about that side of it.

If you have a situation where you cannot get the volume right - a choice between either too quiet or blasting out - that is a pain in the arse as I know from experience. I don't like in-line attunators for the same reason folk have outlined above, but a passive pre-amp would sort the issue out.

I've got a very noticeable channel imbalance with the volume control right down near its lowest setting (a fairly common problem from what I read). This extends into the usable/comfortable volume range and reduces my listenable range to about 15 degrees of the volume control.

What i want to achieve is both to shift the listening range further round the dial, and if possible expand the the range of control that I have. I'm currently listening with the volume control at perhaps half past 7 on the dial, and I can push it up to about half past 8 if I want it pretty loud. I'd much prefer it to be at a normal listening level at perhaps 10 o'clock on the dial (well past the point where the channel imbalance is evident), and have scope to wind it up to perhaps 2 or 3 o'clock if I want it loud.

[struth]

Would think it best overall if you got the inputs levels fettled to modern levels. Shouldnt cost that much and stops the need for an extra box

[Arkless Electronics]

The only practical way of changing the amps sensitivity would be to... fit attenuators internally. I disagree that attenuators are detrimental to sound quality. They are used in several places in your hi fi anyway without you being aware of it! Also in the recording chain... and a passive pre using a switched attenuator is exactly the same in circuitry and effect as something like the Rothwell attenuators.... Imagine it set to half volume and then superglued in place... you could then remove all the other resistors for other volume settings and what you are left with is exactly the same as an in line attenuator.

[Macca]

What is the amplifier?

[Macca]

The only practical way of changing the amps sensitivity would be to... fit attenuators internally. I disagree that attenuators are detrimental to sound quality. They are used in several places in your hi fi anyway without you being aware of it! Also in the recording chain... and a passive pre using a switched attenuator is exactly the same in circuitry and effect as something like the Rothwell attenuators.... Imagine it set to half volume and then superglued in place... you could then remove all the other resistors for other volume settings and what you are left with is exactly the same as an in line attenuator.

I know this is the theory but I have some Rothwell attenuators and there is no question that they have noticeably degraded sq whenever or wherever I have used them. I agree that they shouldn't. But they do.

[Arkless Electronics]

I know this is the theory but I have some Rothwell attenuators and there is no question that they have noticeably degraded sq whenever or wherever I have used them. I agree that they shouldn't. But they do.

Every volume control IS an attenuator of EXACTLY the same circuit as an in line attenuator! So if you are right that means all volume controls and passive or active pre amps, switched attenuator or normal pot, must be having the same effect.... the circuitry is identical!
All amplifiers also have an attenuator exactly the same as these in line ones in the negative feedback loop... It's not a good idea to mess with this for reasons outside the scope of this...
IF the amp has a preamp section before the power amp then it may well be possible to change the gain of this... by changing the values of the identical attenuator in that!

The only other way of doing it would be to use a transformer or autotransformer.... which would be much less satisfactory and introduce its own sound...

[jollyfix]

When i have used my Rothwells, i didn't notice a huge degradation on sq. My amp sounding so much better to be honest.
I used them on a Rega Brio, and Rega Saturn. The amp vol set to say 7.00 o clock nice vol to listen to, at 9.00 o clock amp sounded so much better, but could not listen at that vol for too long.
After i fitted the Rothwells same vol as 7.00 o clock but now amp vol pot at 9.00. Worked well for me.
I have also used a Kimber CD interconnect with -14 db attenuation fitted, did not like that one bit, think more cable prob than attenuation.

[Macca]

Every volume control IS an attenuator of EXACTLY the same circuit as an in line attenuator! So if you are right that means all volume controls and passive or active pre amps, switched attenuator or normal pot, must be having the same effect.... the circuitry is identical!
...

I know, but nonetheless there is a deleterious effect. Maybe it is simply due to adding an additional component in the signal line? It wasn't a huge degredation but it was enough for me to reject in-line attenuators as a viable solution.
This was when I was using a Croft pre-amp, I don't have any issues with the current lash up.

[jollyfix]

Graham i can loan you a set of Rothwell. I can post to you when i get home ( poss end of next week). Give them a go, that way you can hear for yourself whether they make a difference ( good or bad) to your system or not.
Just post them back when you are done. Pm Me your address if interested.

[upperholme]

What is the amplifier?

A venerable Cambridge Audio A1 Mk3 SE - I did say I was doing this on the cheap :-)

[upperholme]

Graham i can loan you a set of Rothwell. I can post to you when i get home ( poss end of next week). Give them a go, that way you can hear for yourself whether they make a difference ( good or bad) to your system or not.
Just post them back when you are done. Pm Me your address if interested.

That's extremely good of you jollyfix. i'll take you up on that kind offer if I may.

[Macca]

A venerable Cambridge Audio A1 Mk3 SE - I did say I was doing this on the cheap :-)

They are good amps. I've heard worse at 10 times the price. :)

[Arkless Electronics]

I know, but nonetheless there is a deleterious effect. Maybe it is simply due to adding an additional component in the signal line? It wasn't a huge degredation but it was enough for me to reject in-line attenuators as a viable solution.
This was when I was using a Croft pre-amp, I don't have any issues with the current lash up.

We'll have to agree to disagree....

As I say there are probably several identical attenuators already in your system... The potential divider is one of the most basic building blocks in electronics.

[upperholme]

They are good amps. I've heard worse at 10 times the price. :)

I've certainly been very happy with it.

[Theadmans]

I bought one of these the other day :-

http://www.ebay.co.uk/itm/182154400546?_trksid=p2057872.m2749.l2649&ssPageName=STRK%3AMEBIDX%3AIT


...seems to work fine. Mind you I don't use it in my main Hi-Fi rig. I had an issue with certain vinyl rips (eg. George 'Porky' Peckham pressings of Joy Division / New Order 12" Singles) being so loud they overloaded Audacity on my PC. My turntable is the Project one with the built in Phono Stage offered with the DeAgostini Jazz issues (so it was the only way I could wind back the levels in Audacity as before even 0.0 in Audacity ran the levels into the red). Lot cheaper than the Rothwell's too!

[danilo]

Buy a pair of these and it's improbable that you will Ever! give attenuation quality any further thoughts.
http://www.intactaudio.com/atten.html

[Idlewithnodrive]

I know this is the theory but I have some Rothwell attenuators and there is no question that they have noticeably degraded sq whenever or wherever I have used them. I agree that they shouldn't. But they do.

This is exactly what I find.

I know that it shouldn't degrade SQ but it does, audibly.

[Macca]

This is exactly what I find.

I know that it shouldn't degrade SQ but it does, audibly.

But for everyone of us who found that, there is an equal number who say: 'Yep, solved my gain issue, no downsides, and I'm as happy as Larry.' So there is clearly some other, unconsidered factor at play.

[fatmarley]

Tried a voltage divider years ago inside my Naim preamp and it didn't sound good.

http://www.pinkfishmedia.net/forum/showthread.php?t=6190 - Read posts written by Andrew L Weekes

[Macca]

If anyone uses the scheme imarks proposes, place the attenuator at the input of the preamp, not the output of the source.

Failure to do this will result in increased source impedance to drive the cable, which could bring an audible rolloff at high frequencies, depending upon cable capacitance.

Andy.

I've used attenuators all which ways on a few combinations of pre-powers and some integrateds. At output of source, input to pre-amp, output to power amp and input to power amp and always had the same result which is to say I could tell straight away that something wasn't right. Nothing to think about. It sounded worse. But in retrospect it could have been this potential issue with the cable capacitance mentioned above. I never tried it with different interconnects.

I think maybe that small increases in capacitance can have a greater effect on the sound than they should do in theory. It would explain a lot of differing experiences where it is assumed that the interconnects or speaker cables used measure perfectly within audible tolerance and are therefore a constant. But I'm not technical so I can't go any further with that.

[Arkless Electronics]

A possible (probable even) scenario here is that if an input is being slightly overloaded by excess signal then a bit of distortion is being caused which whilst definitely a bad thing is adding a bit of "pizzaz" to the sound... attenuating removes the distortion and restores accuracy and some report this as reduced sound quality...

[Firebottle]

Can't really see that Jez, if you are that close to possible overload of any input then I'd say the gear isn't designed with enough headroom.

My feeling is that with additional resistance in line you are losing the 'grip' afforded by the low output impedance of the source.

:)

[Arkless Electronics]

Can't really see that Jez, if you are that close to possible overload of any input then I'd say the gear isn't designed with enough headroom.

My feeling is that with additional resistance in line you are losing the 'grip' afforded by the low output impedance of the source.

:)

If the vol control is cramped down at the low end it suggests excessive gain somewhere, depending on where exactly, the distortion scenario is perfectly plausible.

I'm afraid I disagree with the second part of your post... and with the suggestion that attenuators spoil the sound in fact.... If passing the signal through a resistor has this effect then there would be bugger all sound quality left if you consider how many resistors there are in the chain!

[Macca]

I was suggesting that attenuators in concert with some interconnects spoils the sound due to raising capacitance and rolling off high frequencies.

That is the result I hear when using in-line attenuators - a slight muddying and dulling of the sound. Enough to be obviously worse and not imagination, but not enough to ruin it entirely.

Perhaps with very low capacitance cables the effect would be ameliorated beyond audibility.

If we are more sensitive to small increases in capacitance than is thought then this would make sense. The point at which electronic engineering meets psycho-acoustics is still a grey area.

[struth]

Could be Martin. Capacitance issues can be audible. Ive heard it myself. As for excessive gain etc, i dont see it as the cause. The 6watt amp i got recently cant get above 2/3 notches with my speakers, pretty much same as more powerful amps. It pretty even across the inputs of cd, rpi and vinyl.

[Light Dependant Resistor]

17584
If the vol control is cramped down at the low end it suggests excessive gain somewhere, depending on where exactly, the distortion scenario is perfectly plausible.

I'm afraid I disagree with the second part of your post... and with the suggestion that attenuators spoil the sound in fact.... If passing the signal through a resistor has this effect then there would be bugger all sound quality left if you consider how many resistors there are in the chain!

The answer is to rid yourself of switch contacts forever
2 light activated light dependent resistors per channel offering
100 ohms to 20 meg ohms, removing all ( other than the RCA itself)
switch contacts. Or variable transformer coupled attenuation
or not quite as good digital attenuation.

[Arkless Electronics]

I was suggesting that attenuators in concert with some interconnects spoils the sound due to raising capacitance and rolling off high frequencies.

That is the result I hear when using in-line attenuators - a slight muddying and dulling of the sound. Enough to be obviously worse and not imagination, but not enough to ruin it entirely.

Perhaps with very low capacitance cables the effect would be ameliorated beyond audibility.

If we are more sensitive to small increases in capacitance than is thought then this would make sense. The point at which electronic engineering meets psycho-acoustics is still a grey area.

It's possible yes but would generally take quite long interconnects to cause this... putting the attenuator at the load end of course removes this possibility;)

[Arkless Electronics]

17584

The answer is to rid yourself of switch contacts forever
2 light activated light dependent resistors per channel offering
100 ohms to 20 meg ohms, removing all ( other than the RCA itself)
switch contacts. Or variable transformer coupled attenuation
or not quite as good digital attenuation.

'Fraid I couldn't disagree more.... and who mentioned switch contacts?

[Macca]

Grant - I think I have, when comparing interconnects. Different interconnects, that do not have any parameters extreme enough on paper to influence the sound, still sound different to me, in the high frequencies. Not by much but enough for me to have a preference. As Jez has said before, that is impossible from a technical point of view but the technical point of view still makes assumptions about psycho-acoustics that are not necessarily gospel.

I like to have technical explanations for what hear. If you understand how a mechanism works then it is easier to improve it, rather than just spending more money blindly and getting no-where, or just getting 'different' instead of better.

[struth]

Grant - I think I have, when comparing interconnects. Different interconnects, that do not have any parameters extreme enough on paper to influence the sound, still sound different to me, in the high frequencies. Not by much but enough for me to have a preference. As Jez has said before, that is impossible from a technical point of view but the technical point of view still makes assumptions about psycho-acoustics that are not necessarily gospel.

I like to have technical explanations for what hear. If you understand how a mechanism works then it is easier to improve it, rather than just spending more money blindly and getting no-where, or just getting 'different' instead of better.

Sure, a modicum of knowledge is good. Chasing the perfect spec amp is pointless to me as you might not like how it sounds. If i like someting i like it.. Dont really care if its " inferior " to anther amp i dont like the sound of as much and costs 10 times as much. Ive been lucky to hear a lot of nice systems, and quite a few of mine have been nice..one or two, er we shall skip over lol. Ive got the sound i like and i now always say find a set of speakers you love and are an easyish load, then the rest is fairly easy. Tweaking cables at end will just top it off. Often the home made or ones you pick up fairly reasonable are better than super expensive ones as well. For instance Brians ones are great, as are the ones Geoff made me. My own build speaker cables did ascwell as some expensive kimber ones, so there you go. Beat the talk ones easily

[Macca]

Part of the problem is no-one really likes to admit there is a lot we don't understand in how using varying electrical voltage to create standing waves in air is actually translated in our brains into 'music', and then there is another leap to 'an enjoyable sound' or a 'good sound.'

Why can you hear £100K of kit at a show and it sounds unpleasant but your mate's Denon mini-system playing in the background catches your ear with how good it sounds?

Sure there is a technical/psycho-acoustic explanation but we don't know what it is as if we did there would be no £100K horror stories to listen to.

[Light Dependant Resistor]

'Fraid I couldn't disagree more.... and who mentioned switch contacts?

But have you listened to each method where switch contacts are removed. ?
or are you just guessing that nothing changes when switch contacts are removed ?

The second part of your post, It is implicit in your post where you say "passing signal and
how many resistors are in the chain " that there has to be some method of moving from one resistor
to the next but if you have have no method to vary attenuation and are happy to have one volume setting
and to patiently solder two well chosen for audio purpose resistors per channel many times a day in a L pad then
Yes you could indeed ignore switch contacts, or for that matter the better suggested switch -less
methods of attenuation.

[Light Dependant Resistor]

Part of the problem is no-one really likes to admit there is a lot we don't understand in how using varying electrical voltage to create standing waves in air is actually translated in our brains into 'music', and then there is another leap to 'an enjoyable sound' or a 'good sound.'

Why can you hear £100K of kit at a show and it sounds unpleasant but your mate's Denon mini-system playing in the background catches your ear with how good it sounds?

Sure there is a technical/psycho-acoustic explanation but we don't know what it is as if we did there would be no £100K horror stories to listen to.

One of the best articles on cables at audio frequencies is here: http://www.waynekirkwood.com/images/pdf/Cyril_Bateman/Bateman_Speaker_Amp_Interaction.pdf

[Arkless Electronics]

But have you listened to each method where switch contacts are removed. ?
or are you just guessing that nothing changes when switch contacts are removed ?

The second part of your post, It is implicit in your post where you say "passing signal and
how many resistors are in the chain " that there has to be some method of moving from one resistor
to the next but if you have have no method to vary attenuation and are happy to have one volume setting
and to patiently solder two well chosen for audio purpose resistors per channel many times a day in a L pad then
Yes you could indeed ignore switch contacts, or for that matter the better suggested switch -less
methods of attenuation.

:ner: Sorry, not interested....

[Light Dependant Resistor]

:ner: Sorry, not interested....know now
At least we now know, you are not interested, and can move the discussion along .

[George47]

I have yet to hear any plug in attenuators even when using ultra transparent resistors not have a detrimental sound effect.

What he said, which does not help. I would have offered you the in-line attenuators I had but I have already given them away.

[Arkless Electronics]

If the op can borrow a passive switched attenuator he can try different attenuation settings for himself to ascertain the best setting and also decide if it spoils the sound.... A fixed attenuator of the optimum value can then be substituted.

LDR attenuators are not relevant to the discussion on fixed attenuation. As they generate measurable distortion they are IMHO not the best choice for a passive anyway...

[Light Dependant Resistor]

If the op can borrow a passive switched attenuator he can try different attenuation settings for himself to ascertain the best setting and also decide if it spoils the sound.... A fixed attenuator of the optimum value can then be substituted.

LDR attenuators are not relevant to the discussion on fixed attenuation. As they generate measurable distortion they are IMHO not the best choice for a passive anyway...

Your back ! Can you provide those measurements ? ... and you are wrong

[Arkless Electronics]

Your back ! Can you provide those measurements ? ... and you are wrong

We know a man who can... Up to him to publish here if he feels like it... As to "I'm wrong"... well even the manufacturers of LDR's admit to the distortion!

[Light Dependant Resistor]

If the op can borrow a passive switched attenuator he can try different attenuation settings for himself to ascertain the best setting and also decide if it spoils the sound.... A fixed attenuator of the optimum value can then be substituted.

LDR attenuators are not relevant to the discussion on fixed attenuation. As they generate measurable distortion they are IMHO not the best choice for a passive anyway...

Quite the opposite - every type of attenuation should be explored
and Yes you are quite correct LDR's are variable attenuators, their benefit that you have stated no
interest in, so for other readers is, to opto couple change of resistance
thereby avoiding the detrimental switching action or wiping action of potentiometers.

Other coupled types avoiding direct switching and able to work varying resistance being
transformers, and to a degree digital pots as resistance is then varied in the digital domain

Having knowledge of the benefits of each type of attenuation is very rewarding, you are then in a position
to have some knowledge how audio optocoupling vs stepped attenuation vs transformers
can benefit your audio system. Ignoring or " i'm not interested " in the frame of this thread
is displaying ignorance, it is after all about advice on attenuation - not as I see just types
that you are comfortable with - or in this case living on your own very small isolated island with.

Cheers / Chris

[Light Dependant Resistor]

We know a man who can...! Yes I have acquired a ST1700B
needing its power supply repaired ... so look forward to doing just that.



As to "I'm wrong"... well even the manufacturers of LDR's admit to the distortion!

Yes, with far more honesty than do stepped attenuator manufacturers, who quietly hide in the hills !

With some LDR circuits ( although surprisingly, still good sounding ) you will see no separation of the cathode return from
signal earth, soggy power supply capacitance on voltage regulator outputs and zero attempts at proper current regulation.

Sadly it is from these types of " I don't care it will work anyway " circuits that opinion on LDR's is usually based
Here you can see both myself and Morten from Tortuga commenting on a typical -she will be right there is,
and cannot be anything more, because I do not want to lift a finger or let alone listen assumption.

http://www.diyaudio.com/forums/analog-line-level/238040-2-5v-achieves-lower-distortion-ldr-nsl32sr2-2.html

Best audio IMHO surpassing stepped attenuators and digital pots, occurs when high impedance
circuitry is used, centred around required current delivery - no more no less. It is from building
current regulators that actually perfectly suit the NSL32SR2 and SR3 that I know how good LDR's are
for audio. The higher impedance you can design for, the better they also get.

I have built and used stepped attenuators, being at one time the Australian agent for Audio Synthesis, and
similarly have a digital PGA2311 just to see how poorly they compare.

So there is very good reason for readers to assess for themselves every type of attenuation
and not to just accept switched or wiping resistive paths to be the only type.

It would be good to hear from those with first hand knowledge of other attenuation methods..

Some info from Silonex who state: http://www.cresttech.com.au/pdf/Silonex/levelcontrol.pdf

" The measurements of the various circuits were taken with an
input level of +10 dBu at 1 KHz, and the distortion (THD+N)
measured with a 30 KHz bandwidth. Although some of the
distortion figures may seem less than ideal, 3 factors should
be borne in mind:
1) These measurements were taken at fairly high levels,
typically corresponding to –6 dBFS on professional
equipment, and will decrease rapidly with input level
typically being 3 to 4 times less at 0 dBu, and virtually
unmeasurable at –20 dBu.
2) The distortion products produced by an Audiohm coupler
are all low order, second and third harmonics, which are
much less objectionable than high order harmonics
produced by crossover artifacts.
3) In the series/shunt and hybrid series/shunt attenuator
configurations the worst distortion occurs at high
attenuations, where the output signal level is so low that
the distortion is unlikely to be very noticeable."

Cheers / Chris

[danilo]

:eyebrows: http://www.intactaudio.com/atten.html

[Light Dependant Resistor]

:eyebrows: http://www.intactaudio.com/atten.html

Nice, have you heard one in your audio system ?