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Preamp puzzle - power supplies, tubes vs. solid state, volume controls...

naimnut

naimnut

Deep in the Mines of Soul
I am looking for the experience and thoughts of others here, who have owned or listened extensively to a wide variety of preamplifiers. I want to learn more and hear different perspectives to help guide me if I choose to replace my venerable Naim 82.

I read with great interest the recent thread of Naim 252 vs. Teddy Pardo PR1. I also have been reading a long and fascinating thread regarding some Esoteric Audio Research preamplifiers and amps. Earlier this year there was another thread regarding the Khozma Acoustic passive preamps, which got me off on a tangent of looking at volume controls.

I still have everything in the world to learn, but I'm left with the sense that the performance of a preamplifier is most strongly associated with at least two things - the power supply and the volume control. Other factors, such as whether it is built using solid state devices or tubes, is less important than how well the designer conceptualizes the design and how well it is executed in the factory. It seems Teddy Pardo has done an outstanding job designing and building a very competitive sounding preamp at a very affordable price, so that's cool. I recently spent time reading and watching the youtube videos about the Prima Luna Dialogue HP preamp, which boasts tube rectification, which seems to be important. The First Sound preamplifiers built by Emmanuel Go seem to be on a whole different level, with power supplies and volume controls taken to the extreme.

So, given all these factors, and a not-unlimited budget, what do those of you who prefer tubes have to say? What about those who prefer solid state? Anyone gone back and forth? Where's the sweet spot? What say ye?
 
Just a quickie on this cold Tuesday morning to start you off. I had Naim, from 42/110 through most to 552/135s. Changed 135s to old E.A.R. (as mentioned above) 509s. Improvement wrought in fluidity, tactility and generally organic presentation.

Two years ago I replaced the 552 with E.A.R.'s 912 pre. Not only did my ESLs (Quad 2905s) come alive in every sense, but I got rid of a few boxes and achieved cash inflow as I had Superline/S'cap, Burndy & HiLine plus other bits, completely replaced and upgraded by the on-board stages of the pre.

As I previously had ProAc R4s, I know that both dynamic and ESL speakers have benefitted from my change of horses. E.A.R. is near St. Neot's (Cambs.) and servicing etc. much cheaper than Naim (as you might expect). Depending on what your speakers are, going with this (or Prima Luna ?) route but scaling down in pre. (still with mm.mc stage) and int. power might satisfy you for a fair old time. Both Naim and E.A.R. have their pros and cons (although I'd never revert), the latter is about as near in valves to the s/s Naim as you'll get. I suffered no culture shock when I changed power amps.

Not such a quickie, then, but that's hifi ! :)

Ps. Don't worry about off-board power supplies or lack of. It depends upon the design, and to a certain extent, the difference between valves and s/s.
 
I recall an article, possibly in Stereophile magazine, some years ago, purporting to list the world’s ten best preamps. Linn’s Klimax Kontrol was somewhere in the ten, and the only solid state box in the list, which does suggest that design and implementation matter more than ss v tube, although it does also suggest, in a list containg 90% tube preamps, that a tube design approaches ‘best’ more easily than ss.

Mick
 
I'm a firm believer in the idea that no component in the chain can 'add' quality, it can only reduce the quality, or fidelity as we call it, of the original source music. We have no control over the bit from instrument to recording, but after that each component in the chain from LP/CD/FLAC file to the speakers has the potential to lose some of that fidelity.
A pre-amp has, historically, had many functions, tone controls, filters, equalisation have all featured in the past but seem much less relevant today, so we are generally left with two functions - volume control, and input switching. Many people have one-source systems, so the preamp them becomes just a volume control, and as sources such as CD players and streamers have generous output, then the preamp isn't really amplifying, it is just attenuating.
I had a NAC82 and was thinking of upgrading it, but I decided to have it serviced first, as it would be easier to sell, and the upgrade may well be enough for me to be happy. As the preamp was going to be away for a time, I built a passive volume control from a moderately priced potentiometer I had in my junk box. When the 82 came back I realised that the cheap pot was at least as good as the 82, possibly better. I them compared my cheap pot, with the digital volume control on my DAC, and the DAC on its own was notably better!
I've not used a preamp since. I'm going to be splitting my system into a dedicated vinyl system and a digital system soon, so each will be a single input system, so no switching functions will be required. The digital system will use the DAC as volume controller, and the analogue system will use a passive attenuator as my power amplifier is quite sensitive amd the phono amp has plenty of gain. For me, preamps are a thing of the past, which is a shame, as I always rather liked them, as objects!
 
Is it really true that a preamp with once source is just attenuating? I’ve tried both a Quad preamp and a Tisbury passive, and I much prefer the imaging with the quad - no tone controls in use. So I’m wondering how this could be unless the problem lies with the Tisbury, I’m sure there are better passive pre amps - maybe the Quad is just a better attenuator!

The Tisbury is less 3D, more forward, brasher.
 
Hi,

As always you will get many differing thoughts on the changing of any part of the HiFi chain.

I have a number of pre amps, amps, speakers and sources.

As a general rule the pre amp used with the same make of equipment as the amp, e.g. Naim/Linn/Quad will give the signature sound of the manufacturers equipment. What I mean by that is the Naim signature sound with say a Linn pre amp does not sound the same as it does with a Naim pre amp.

The best passive pre amp I have heard was a Tortuga LDR1 with a battery power supply, not the latest Tortuga passive pre amps as they are not in the same league as the original LDR1, not just my opinion. I have also used the Tisbury and EVA 2 LDR passive. Not even close to an LDR1. Have used them with different power amps, Linn, Naim, Meridian, Quad and Musical Fidelity, not a huge variety but enough to show the differences.

For example, I have a complete Linn system, sounds very accurate, detailed and dynamic, however it is somewhat boring to listen to after a while. I can replace the pre/amp with a Naim 12s/Snaps/250 but leave the source and speakers the same and the music although slightly less accurate and detailed, (only by a small amount) has that PRAT that is talked about with Naim, and of course easy to listen to for hours on end.

I am sure many will tell me it is the room or some other such thing, however if I then replace the Naim's with an all valve set up using the Quad QC24 pre and the Quad II Classic amps the sound changes, the sound stage becomes bigger and gives a more 3D presentation, it's about as accurate and detailed as the Naim however the sound has a warmer feeling, maybe the valves give that, but it does not have that PRAT feeling that the Naims have, again my opinion.

I also have a few different speakers and sources to play with but the basic differences are with the amplification, that is the pre and amp. Yes the sound changes with a different source, more or less detail, more dynamics, same applies when I change speakers, but it is the way the sound is presented by the pre and amp combination that stays the same. In other words whatever source or speakers I use the Linn will always sound rather too accurate and boring, the Naim with have that amazing PRAT as it is called and the Quad valve system will always sound warm with a big 3D soundstage.

Which do I prefer, I like them all, for different reasons, the type of music played what time of day it is, what mood I am in, but if I was to pick one system I would choose the Naim's, it also gives one thing I have not mentioned before, the Naim's seem to give emotion to the music that the other two I have mentioned just cannot quite give. These Naim's are of course older, the classic range as some call them, maybe that has something to do with it. I know people who have new Naim's but changed back to the old Naim similar to mine, as I say it is all down to what you prefer not anyone else.

The other thing that makes a big difference and allows the electronics sound their best is speakers, speakers that stand out, for me at least, Shahinian, Quad ELS 57, 63's and Linn Isobarics, there is just something about them that makes you want to listen to the music not the HiFi, those speakers give emotion that no other speakers I have heard can give, again my opinion.

Cheers

John
 
It makes no difference how many inputs there are.

A passive pre (a terrible name for them but it's stuck...) always attenuates until it's at maximum volume, in which case it just allows the input signal straight through to the power amp. Variable attenuator control unit would be a more apt name!

An active pre can amplify or have no gain depending on the design but in practice will usually be attenuating overall even if it has gain, ie if it has x 4 gain then the vol control position will be much lower, but as a CD player has about 2V output we hardly want to amplify it to 8V before feeding it to a power amp!

Impedance matching has a very specific meaning in electronics and this is not impedance matching.
Ideally a pre should have a very high input impedance and very low output impedance but there are no specific figures to try and match to. In practice "what you can get away with" can vary over a quite wide range depending on individual circumstances and equipment used. A 20K passive will have 5K worst case (at half vol) output impedance
which will still be OK to drive 10m of 100pF/m coax for a -3dB point of 31KHz.
An active pre will usually have an output impedance of a few Ohms to 1K or so.

Power supplies are of little importance in a line level pre (ie no phono stage built in).
 
In my main system I have five sources - two turntables, two CD players and a cassette deck. Soon I will probably replace one of the CD players with a streaming option. So source selection is a consideration in any change going forward.

The story above about the volume control is a lot like the narrative Emmanuel Go has on his website, and he's ended up within active designs. Just another thing to try to understand better.

Thanks, all, for sharing.
 
Buy carefully second-hand and audition at home at your leisure.
If the venture is a mistake, you'll about break-even. Far better/easier than any other option, including trying to decipher anyone's description and deciding if it would appeal if you took that route.
 
I’m pretty much single source, digital, so When I went over to a Teddy Pardo set up, I bought a TeddyDac VC model, that is to say the version with built in volume control. It’s an analogue volume control, so not much more than a passive control, but according to the specs, the VC model has a maximum output of 6V rms. Not surprisingly, I doubt if I ever go beyond 1/2 volume at the greatest, but it sounds very good. OTOH, I have tried a passive volume control (NVA) off a standard CD player with output of 2V and somehow it didn’t quite do it for me, even pushing the volume up, which had to be close to the maximum anyway. Possibly an impedance mismatch, but I think using a standard 2V output source into a passive is a bit of a lottery.
 
I'm with JemHayward and simply do not get how a pre-amp can add anything to the quality of the signal. If it does, it is distorting it. It is meant to switch and attenuate. The active element of it seems to be a legacy concept.

The only pre-amp I ever had was a Hattor with dual mono Khozmo attenuators, so no external power and the signal goes through two resistors. It cost $800, about £550 at the time. It did its job perfectly.

Like JemHayward, for a few years I used the digital volume control in a PS Audio PWD MkII DAC - it was superb.

I was amazed to see that the £6,500 NAC252 (before the "mandatory" £4,500 power supply) uses a couple of ALPS Blue motorised potentiometers, total cost including remote unit is £100. I find that a little worrying.

If you want a clever pre-amp, look at the PS Audio BHK, which has a hybrid valve and stepped attenuation volume control. Auralic do similar with a hybrid digital and solid state arrangement.
 
I’m going to ask what may be a really stupid question?

I’m using a quad 34 to pass the signal to my Quad power amp. All tone controls defeated. Is it operating just like a passive preamp? I mean, why do I need to plug it in?

I know it sounded different from my passive preamp. I just want to get clear why. It could just be bacause the components were different, but it could be something else too.
 
mandryka said:
I’m going to ask what may be a really stupid question?

I’m using a quad 34 to pass the signal to my Quad power amp. All tone controls defeated. Is it operating just like a passive preamp? I mean, why do I need to plug it in?

I know it sounded different from my passive preamp. I just want to get clear why. It could just be bacause the components were different, but it could be something else too.
Click to expand...

No it's still active! 30P op amps (several) and lots of active cmos electronic switches through which the signal must pass...
 
So basically it's colouring the signal, in a way that, I guess, the designers planned. That's to say, they had a Quad sound in mind, and using a Quad preamp is all part and parcel of making that sound happen.
 
mandryka said:
So basically it's colouring the signal, in a way that, I guess, the designers planned. That's to say, they had a Quad sound in mind, and using a Quad preamp is all part and parcel of making that sound happen.
Click to expand...

I'm certain Peter Walker wouldn't agree there is any "planned colouring", at least not when the tone controls are set to the neutral position. He argued that an ideal amplifier should be like a wire with gain, so would totally refute the concept of a "Quad sound".
 
gustavm said:
I'm certain Peter Walker wouldn't agree there is any "planned colouring", at least not when the tone controls are set to the neutral position. He argued that an ideal amplifier should be like a wire with gain, so would totally refute the concept of a "Quad sound".
Click to expand...

That said, he did tailor the LF and HF roll-offs to suit the ESLs and give the bandwidth he felt appropriate. But he would certainly not have regarded this as 'colouring', just choosing a sensible audio bandwidth, and was satisfied it wasn't audibly a problem.
 
Worth adding that a well-designed active pre-amp should normally have high-impedance inputs and low-impedance outputs, in order to reduce the sensitivity to the actual output impedance of the connected source, and the input impedance of the power amp. A passive pre-amp (aka attenuator) can't achieve this in all cases, indeed its input impedance may depend on the input impedance of the power amplifier and also vary with different volume setting. In practice if the output impedence of the source is low, and the input impedance of the power amp is high (as you would normally expect them to be), the effect should be small.

And while its certainly true that PW would take the line I suggested above, it is of course another question as to whether he succeeded or not! I don't think the Quad 34 is the most transparent I have heard.
 
gustavm said:
Worth adding that a well-designed active pre-amp should normally have high-impedance inputs and low-impedance outputs, in order to reduce the sensitivity to the actual output impedance of the connected source, and the input impedance of the power amp. A passive pre-amp (aka attenuator) can't achieve this in all cases, indeed its input impedance may depend on the input impedance of the power amplifier and also vary with different volume setting. In practice if the output impedence of the source is low, and the input impedance of the power amp is high (as you would normally expect them to be), the effect should be small.

And while its certainly true that PW would take the line I suggested above, it is of course another question as to whether he succeeded or not! I don't think the Quad 34 is the most transparent I have heard.
Click to expand...

I already covered all that in post 8... agreed that the 34 is not the most transparent pre amp...
Many seem to prefer a pre amp that messes with accuracy and transparency though. There seems to be a market for valve pres that sound very obviously valvey in a "warm and cuddly and won't frighten the horses" way for example.

The best hi fi equipment available from a range of manufacturers should in theory sound almost identical if they are all going for the ultimate transparency and accuracy and are all getting close to perfection! If a perfect pre adds nothing and takes nothing away then all perfect pres would sound identical...
 
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