Valve amp curiosity

[phillil]

For ages now I've often wondered how valves would sound hooked up to my 802D2's.

I've been tempted by a couple of the integrateds I've seen here on the Wam, but don't really want to just buy something only to lose money if I really don't like it.

I heard a demo of the 802D's hooked up to an Icon Audio PP20 (I think) but it didn't sound very good. But then I don't think the listening environment was ideal and it was all a bit rushed.

Since my DAC is integrated into my pre-amp, I'm thinking I should really just try and find a valve power amp else I'd also need to buy a DAC. Or I could just line-out from my Classe, as I'm sure sonically the valve amp would have more of an effect than the Classe anyway??

So any advice would be greatly appreciated, as would a loan possibility close to me. I don't mind buying one if someone has experience of a similar setup, or if it's a deal too good to be missed!!

Thanks

Lee

[Effem]

My recollection of the 802s is that they are none too sensitive and need some decent welly to get them on song, although in a small room with modest volumes a valve amp may suit if you don't need high volume levels.

I have generally found a valve pre and SS power amp a better combination than t'other way round, but then again room size, budget, etc., could reverse that situation.


It would therefore be helpful to us to know your room dimensions and of course your budget before we make any judgements :eyebrows:

[ppat2]

Hi Lee,

I was in a similar situation to you and just in the past 2 weeks, upgraded to a valve amp.

BTW, check out this link on AOS for some feedback that might interest you.
http://theartofsound.net/forum/showthread.php?t=24157

I don't have large 802's like you. I am using Proac monitors, the Response D Two's.

My room is (in feet) 26 x 12 x 9.

My amp is the Air Tight ATM-1, a 15 year old amp and it puts out 36w per channel of Class A power.

My previous amp is a newer model NAD amp, the C275BEE, that puts out 150w of class A/B. A great amp.

My concern moving to a lower powered tube amp, was would it have enough power to do the job. My speakers are 88.5db, more like 88.

Surprisingly, the tube amp in every facet has been a better match than the NAD, and the power output from my system is far more than I can use, and crisp clean with no distortion even at rock n' roll party levels.

This surprised the heck out of me, that a 36w amp could power my speakers better than a 150w amp and in my room size give me more output than I can use. There is something about class A that I don't understand, or some special synergy with this amp and my speakers, that just works. Or some other spec. One of the AOS members noted the size of the output transformers on my tube amp and said that could be the reason.

I am using my NAD C165BEE preamp with the Air Tight, and it is a great match and not out of it's league. There is a synergy there as well.

From what I have read over the years, you have to take a lot of care in matching tube amps to speakers if you have a large room and/or plan to play it loud. You can find yourself in a situation where your amp runs out of steam. I don't believe most users will get a match like I did. It seemed to be chance and my good fortune.

BTW, I am not recommending the Air Tight amp to you. So many good tube amps out there, and many with much higher watts than my amp. I dont see why you could not get a good match. Just shop carefully, and if you can find a dealer or private seller who will let you demo at your home. My dealer let me take the amp home for a week to try, and was I ever hooked. I have listened to solid state for 30 years, no way I was letting this amp go back after hearing how it matched with my system.

Besides having more output, it has far more delicacy and definition than my previous amp, more power output, far better bass control, better pitch and timbre, and overall just more musical. Even though I loved the NAD amp, the solid state in comparison just sounded less musical and more mechanical.

I had B&W 685's and also 603 S3's, and noted that in both the aluminum tweeter was on the dry and bright side. A tube amp would have helped back then to tame that some.

You have the diamond tweeters, and what I have read they have smooth extended highs. The 802's have solid bass too, and depending on your choice of music, a tube amp may or may not make sense in your case. If you like techno and hard rock, you will need a tube amp noted for it's bass delivery.

However, in my case, the bass output now is both deeper and better defined than before. It is interesting that a reviewer said to not use the ATM-1 if you needed deep solid bass. That proved to be opposite in my situation.

So, a lot of comments there. My top recommendation? Demo the amp at home with your gear, and you will have your answer one way or the other.

[phillil]

Thanks for the comments guys - appreciated

My system is kind of in half of our lounge / diner, and is open plan other than a large double sided fireplace inbetween the 2 rooms.

The lounge is about 17x18ft with 11ft high ceilings. The adjoining diner is about 20x15ft, which tends to suck a lot of bass energy out of the lounge.

So the 802's have plenty of room to breathe and do sound wonderful and are well suited to the room and the Classe 400W mono's.

That said, what's really fueling my curiosity and why I'm not overly concerned about power is that I recently sold my Dad's Naim Nait 1. It's only rated at around 20W but drove the 802's fine.

What also surprised me was how they managed to make my large 802's disappear!! The soundstage was completely different with the speakers sounding further away and a bit more 2D.

Switching back to the Classe immediately yielded a more 3D soundstage as the sounds leapt out at me, which also revealed a more cleaner detailed sound.

So I guess I'm looking to recreate a similar experiance to the Nait 1 - although I ultimately wouldn't have kept the Naim, I just enjoyed the drastic change (especially the soundstage) it made to my system.

I just have this notion that introducing valves into my system would offer a refreshing change should I feel the need, and may even be tempted away from my Classe mono's

Regards

Lee

[Sovereign]

You mentioned borrowing a valve amp, where do you live?

[jandl100]

Big B&Ws - as Franky-Boy says, you need serious current heavy welly from an amp to drive those with grip and volume.

I love valve amps, but I seriously doubt they would work well with 802s. Even at lower volumes I'd expect the sound to wallow a bit.

If your heart is set on trying valves - think BIG and seriously heavy .... ;)
Or maybe a hybrid with valve input stage and tranny output. Or a valve pre-amp / tranny power. Or a CDP / phonostage with valves in.

ime big B&Ws are like big KEFs - seriously boring with any but a big current amp, but they come to life with a lot of juice up the jacksie. :)

[Audioman]

I would suggest some of the big Icon Audio mono block valve amps. They should have enough welly for B&W 802 and a more lush presentation. Must say whenever I have heard B&W at shows with the Classe amps I was left rather underwhelmed by the lack of musicality.

[phillil]

You mentioned borrowing a valve amp, where do you live?

I'm in Southampton

Thanks
Lee

[phillil]

I would suggest some of the big Icon Audio mono block valve amps. They should have enough welly for B&W 802 and a more lush presentation. Must say whenever I have heard B&W at shows with the Classe amps I was left rather underwhelmed by the lack of musicality.

....and that's what I'm worried about.

I love the sound of my set-up, but I don't know any different as I haven't really heard much else.

Using the Naim Nait 1 really opened my eyes to how different music can sound.

I get and understand overall quality and detail, but it's the character and presentation I'm not so familiar with.

[ppat2]

Being new to tube amps, I have to admit I don't understand why my 36W tube amp is able to drive my Proac monitors at only 88db sensitivity, to much higher and cleaner levels than a new model NAD 2 channel amp at 150w per? It truly sounds now like 48 inch towers with some serious bass drivers.

I am also using the 8 ohm taps, and will try the 4 ohm taps tonight. I expect I'll get even more oomph then? Hard to imagine, it sounded like Green Day were performing in my living room last night, with no distortion or breakup, and only half throttle on the volume dial, and the amp and preamp attenuators both turned down by 25%.

I think the idea that you "always" need a big heavy tube amp with high wattage, should not apply if the speakers are reasonably sensitive. I see the 802 D's are 90db.

If you can get some loaners, experiment as you have nothing to lose if not paying up front. You might be pleasantly surprised by the difference in presentation from tubes. I personally have been overwhelmed.

[Dingdong]

Best I've heard 802D's sound is hooked up to Icon 845 monos. Most excellent sound.

[Reffc]

Being new to tube amps, I have to admit I don't understand why my 36W tube amp is able to drive my Proac monitors at only 88db sensitivity, to much higher and cleaner levels than a new model NAD 2 channel amp at 150w per? It truly sounds now like 48 inch towers with some serious bass drivers.

I am also using the 8 ohm taps, and will try the 4 ohm taps tonight. I expect I'll get even more oomph then? Hard to imagine, it sounded like Green Day were performing in my living room last night, with no distortion or breakup, and only half throttle on the volume dial, and the amp and preamp attenuators both turned down by 25%.

I think the idea that you "always" need a big heavy tube amp with high wattage, should not apply if the speakers are reasonably sensitive. I see the 802 D's are 90db.

If you can get some loaners, experiment as you have nothing to lose if not paying up front. You might be pleasantly surprised by the difference in presentation from tubes. I personally have been overwhelmed.

The reason that valve amps often sound as though they punch above their weight is because of the way they clip or run into distortion. Most amps are rated at an RMS wattage at 1KHz above which they'll clip or run into distortion which exceeds the manufacturer's stated THD figure for the amp. With SS amps, this distortion is usually odd order harmonics and the clipping can be quite harsh and very obvious. When a valve amp runs past it's stated RMS output for say 0.5% THD, it begins a steady but gentle run into higher distortion which is even order and easier on the ear. It does not clip harshly.

Watts are watts and a SS amp delivering 40 watts is identical in power terms to a valve amp delivering 40 watts. If you are getting more volume from a lesser rated valve amp (compared with a higher rated SS amp) then either the claimed power output for the SS is erroneous or the valve amp is being driven into distortion which is less obvious sonically.

I would not recommend a low or even a medium powered valve amp for B&W 802s. Whilst a 40 watt valve amp may drive them loud in some areas, the response curve for the 802s is notoriously peaky and the phase angles are also very steep. For bass, the power required to maintain a balanced output climbs very steeply so that the in-room response will have peaks and troughs all across the spectrum. 802's thrive on high powered amps and need loads of watts to get the best from them. If you are happy with the sound a valve amp makes with them though, then that's all that really matters.

[ppat2]

If it's distortion I'm hearing at the higher levels, I'll take it!

I use Audio Tools real time analyzer, to measure DB and frequency range of some sample music being listened to.

With my NAD amp, 75 db output as measured by Auditools was all I could take in my room, at my listening distance. Sufficienty loud for these ears. However, above that, it just did not sound so good. The NAD is rated for 150w, but measures 190w on test bench. It is not underpowered, and the output up to the 75-80 db range is pretty special. After that....

With the tube amp, I can run up to 90 db, and the room is rocking and there is no breakup or distortion that I can hear. Even on solo vocals and violin and such. Just stays clean. I don't seem to have a limit on how high I can comfortably listen within this environment, at least tolerable for a rock show...

At higher volumes, I am hearing the same thing I hear at moderate volumes, and cleanly. Maybe my amp is some freak of nature?

I've also taken some audio frequency measurements with audiotools, and with the NAD, there is less bass output below 40hz, then a lot of signal starting at 60 and rising in a relatively steep wave/peak to 750 and then down to about 2k, and that's about it.

Measurements for the tube amp show it to be relatively flat, starting at 25hz and rising more slowly to 1k, and then gently down to 16k, with no missing frequencies in between, other than when the selection of music limits the frequency output. It also measures in the same fashion at low and high volumes.

I guess the term is a flatter frequency response?

Perhaps that would explain why the music sounds so "complete" to me now, and more live and less mechanical, and why I can play it louder with a more desirable result?

I guess my question, in thinking about how many watts are required to drive the B&W's 802 D's, are all watts equal? A $300 receiver from Pioneer might measure 100w, but will that always drive the 802 2d's better than a well designed 50w tube amp for example, to sufficiently loud levels and retaining control of the bass drivers, etc.?

There must be some other aspects at work here, impedance matching, current, quality of output transformer, other build quality, etc. Equal watts can result in very different "usable" output.

For example, it is possible that a 100w Mark Levinson SS amp could drive the 802's better than a 150w SS amp from another brand. That scenario or result is not rare and makes the question of watts more confusing.

[johnwhit]

I guess my question, in thinking about how many watts are required to drive the B&W's 802 D's, are all watts equal?

No, English watts and Japanese watts differ, similar to horsepower. i.e. English horsepower is measured in carthorses where as Japanese horsepower is measured in Shetland ponies:lol::lol:;)

John

[Firebottle]

My guess is the tube amp can match (or tolerate if you prefer) the varying impedance of the 802s a lot better than the NAD can.

The rated output of amps is usually into an 8 ohm resistive load, so doesn't tell you anything on paper as to how well it will perform into a real speaker load.
If the NAD is running into current limiting at 150W into 8 ohms then into the 3.5 ohm minimum load of the 802s it will be running out of steam at only 65W.
Even if this is a 'clean' 65W it is only marginally louder than 40W.

Stick with the toobs,

Cheers :cool:Alan

[ppat2]

But the carthorse and shetland pony example does not make sense. The carthorse is slogging along, kicking up dust and dirt and dragging a heavy load behind it. The shetland pony is prancing along, kicking up it's heels and enjoying life, unburdened by a heavy load. When you take these undeniable facts into account, the pony may be the more effective measure of horsepower...

[Macca]

The shetland pony is prancing along, kicking up it's heels and enjoying life, unburdened by a heavy load...

Not if it's down a pit it's not. Remember that film where they rescue the blind Shetlands from the coal mine? Proper choked me up at the time, that did, although I was only a nipper.

[ppat2]

Too funny Martin, love it! :lol:

[phillil]

OK there doesn't seem to be any offers of loan/buy, what about any other alternative that sound different to my Classe setup??

I've heard Naim gear can sound quite musical?? Anyone have anything for sale/loan??

Thanks

Lee

[Dingdong]

Have a word with Jack at BD Audio. He's got a pair of ex-dem valve monos that would be worth a listen to. They could potentially be a very nice combination.

Not sure about the Naim stuff meself.

[anthonyTD]

Hi All,
I have seen a lot of posts here over the years concerning valve amp and speaker matching etc, and would just like to add my contribution, first of all, its not all about Sensitivity, decent valve amps will happily run 87db speakers if the impedance stays pretty constant with frequency, therefore, when considering a speaker for a valve amp, always study any graphs that the speaker manufacturer has published to first get an insight into what the speaker is doing as far as impedance over the whole audio frequency band, this will tell you much more than just comparing the sensitivity.
amplifiers [especially valve] like see a constant impedance with frequency in order to give you a relatively flat musical presentation, so, if you start off with a nominal impedance of say 8 ohm at around the 200hz mark, but by 2khz the impedance has jumped up to near double that of what is was at 200hz, then its not difficult to assume that the amplifier will put less power into the higher load, its the same the other way, ie at lower frequencies, if for instance, the speakers impedance drops to around half of what its nominal impedance was etc.
So, my advice would be when considering speakers and amp combinations,, always look at all available information, and study it,understand what its telling you, and you will then be much better informed to make your decision.
Hope this helps. :)
Anthony,TD...

[DSJR]

Oh gawd, my Spendors have an impedance curve which goes from 5 ohms at the lowest (very high frequencies) to 6 - 8 over most of the range, but with a hideous impedance peak at 2kHz or so of THIRTY TWO or more ohms, this aspect shared with so many of its brethren at the time, although it's not judged as a "reactive" load I understand, which might upset some ss amps - bloody minefield this innit?

Many modern speakers seem to average around 4 to 6 ohms on average these days in an attempt to pull more power out of the usually ss amp driving them. How do many older valve amps deal with this, as I'm not sure if the 4 ohm transformer taps are enough? Help please Anthony!

[Spectral Morn]

There is a reason B&W distributed and then bought Classe and that is their big speakers work best with SS - not necessarily Classe though.

One of the worst sounds I have ever heard was big 8 series speakers and Classe amps at one of the Dublin HiFI shows back in the mid 90's, it was so bad I walked out of the room.

Now massive stereo, or mono tube amps are a possibility but you are looking at 100 watt ones, from the likes of Balanced Audio Technology (BAT) Audio Research etc and the cost even second hand will be huge.

Amplifiers and speakers purchases should be thought out at the same time or one should avoid buying speakers that only work well with solid state if one might develop a hankering for tubes.


Regards Neil

[Macca]

What about a valve pre feeding a solid state power amp, no worries about driving the speakers and a bit of 'tube magic' injected by the pre?

[anthonyTD]

Oh gawd, my Spendors have an impedance curve which goes from 5 ohms at the lowest (very high frequencies) to 6 - 8 over most of the range, but with a hideous impedance peak at 2kHz or so of THIRTY TWO or more ohms, this aspect shared with so many of its brethren at the time, although it's not judged as a "reactive" load I understand, which might upset some ss amps - bloody minefield this innit?

Many modern speakers seem to average around 4 to 6 ohms on average these days in an attempt to pull more power out of the usually ss amp driving them. How do many older valve amps deal with this, as I'm not sure if the 4 ohm transformer taps are enough? Help please Anthony!

hi Dave,
Indeed it is as you put it "a minefield" but again, some combinations that look hideous on paper can work in certain conditions ie; room environment etc.As a general rule,The simpler the cross-over 'the better the design of the driver, ie, less crap used to correct non-linearities in the driver etc.However, we all know that some manufacturers tailor their designs to suit other products in the chain, so, even then, we cant rely on even the best manufacturers to get it right! As for your dilemma, i would say that running a speaker with a lower [nominal] impedance [in your case 4 ohm] on a valve amp that only has the next best match of say 8 ohm is much better/safer than running say a 16 ohm on the same tap, mainly because we know that most speaker impedances rises with frequency, and some speaker impedances rise quit significantly with frequency, so at the higher frequencies it may present such a small load that the amplifier can be fooled into seeing no load at those frequencies, and become unstable, or at worst, cause damage to itself.
Again, i cant stress enough how important it is to study all available information on possible speaker candidates ie; graphs etc.
Solid state amplifiers' due to their lower output impedance tend to favor lower impedance speaker loads as far as power is concerned, however, valve amps have a much higher output impedance due to the output transformer, [even then fractions of ohms] hence the importance of a continued constant as far as nominal impedance is concerned.
Another important factor is feedback, not only does the use of feedback help to linearize the frequency response of the amplifier, but it also, improves greatly the damping factor of the output stage, this in turn, is very helpful in contributing to the amplifiers ability to cope with varying speaker loads, Thus is why i tend to always disagree with designers and designs that are totally against using any form of feedback. When used in the correct context and amount ie; to enhance an already well designed circuit, Feedback, can be a real asset.
Anthony,TD...

[NRG]

Its a double edge sword. For feedback to work correctly the amp needs to be linear before its applied, applying it to a non linear amp will not make a good amp. With feedback applied the amplifiers frequency response will take on that of the 'speaker given especially given a reactive load. Yes, feedback can work and is needed is certain valve amps but it need to be used with caution and in many cases unwanted.

[walpurgis]

Just get a pair of Lowthers. Problem sorted.

You may have to 'come to terms' with the sound though.

[anthonyTD]

Just get a pair of Lowthers. Problem sorted.


You may have to 'come to terms' with the sound though.
:eek:
Nice one Geoff!
And although i agree [mostly] with your findings having owned them in the past, even they have a place in certain systems!
Single drive units designed well are indeed a good compromise over much of the mass produced multi-drive unit types we have all become accustomed to over the last 30 or so years.:)
A...