Let's talk about pre-amps!

[opnly bafld]

What I think some are saying (I could be totally wrong) is that IF we can have a neutral preamp, then we should be better able to find sources that have the sound we want in our systems and we should be better able to find amps that interact optimally with our speakers.

Personally, I find the 1,000s (10,000?) of possibilities of component combinations daunting.
How could I ever find the combination that will make ME happy?
For this reason I like it when reviewers* and forum members, that seem to have similar tastes as myself, have the same amp/speakers/CD player/preamp (pick one or two) as myself. Then when they try new components with the one that I own, their experience can help narrow down the field for me and it may just be a placebo, but it has worked out good more often than it has failed.


as always YMMV,
Lin

NOTE: the word "IF" is a big word.......and sorry for the OT.
*BFS is one that comes to mind, I have really liked every thing I have bought from Marty's recommendations, even so, we do disagree sometimes (single drivers and tube amps for example).

[richidoo]

OK, now I'm starting to get it.  Thank goodness.  The idea is to pile as much of the voltage gain in the system into one box which is highly optimized for that purpose. This will reduce distortion compared to what cost and space-compromised source output stages can provide. A single, dedicated gain circuit is more efficient in price/performance than the circus we have now, with layers of compromise (CD player volume controls) stealing the thunder of the preamp and hurting system performance.  Eliminate as much of the poor sounding gain in the system as possible and move it to a clean sounding active preamp. With sources relieved of gain (and attenuation) duty, they can focus only on sounding good at 0.5Vpp with moderate output impedance.

Preamps fed by sources with compromised high gain output stages and built in volume control pots must add pleasant distortion to paint over the less pleasant sounds coming from the source. But when the preamp is voiced to sound 'good' on all sources, then details are lost with the intentional blurring of added pleasant distortion whether resonance, harmonic distortion or EQ filtering. If the source signal can be cleaned up by removing the source's output stage which is necessarily compromised by cost and space then the system's active preamp can be rid of its 'voicing' compromise and offer low distortion gain and preserve detail.

So, is the simple solution to this to bypass the output gain stages of our sources as done by many digital source modders and run them into a transparent active preamp? It is starting to make more sense to me. Thanks Steve, that is great idea to think about. You really are a voice in the wilderness though aren't you?
Rich

[bpape]

OK.  Then I'm getting more confused.  If we're shooting for only one gain stage, then the preamp should provide zero gain - correct?  The amp will always provide gain - that's it's purpose.

Bryan

[richidoo]

You're right Bryan, but you're still hung up on that pesky reality. You gotta get over that and demand perfection where it is completely impossible!!    Decent audio power amps are pretty transparent, even at relatively low prices because they are focused on low distortion amplification as their purpose. Preamps are focused on changing the signal to make it sound better, and sources use gain which sounds worse than what the dedicated preamp would do. The goal would be to eliminate those problems by making the preamp the voltage gain. From reading Steve's white papers, I believe he is suggesting that the preamp would be the ideal voltage gainer to maximize S/N and low distortion in the critical voltage gain. Then the power amp would provide only current to power mechanical speakers which need watts. Steve says that what we think of as power amps, actually have a preamp stage built in when they ad 26dB of voltage gain. They should ideally by focused on being a current gaining powersupply to be modulated by ultra precise full voltage signal from the preamp.  In that case though, pre would need to make 60dB+, is that practical? I guess mc phono and ribbon microphone preamps already do it with nice results, but not outputting the kind of absolute voltage that a current only power amp would need (60V?). Changing the low voltage interconnect from pre to amp into high voltage signal would lower noise and lower the cost too, but better shielded wires would be needed from source to preamp with no source output stages. So in today's reality a power amp sharing the gain seems to make sense as long as it is low distortion, not trying to mess with the signal transparency. That's my take, and I am likely at least partly still confused but don;t know it, so take it FWIW.. I hope Steve will chime in here and correct me.

[opnly bafld]

OK.  Then I'm getting more confused.  If we're shooting for only one gain stage, then the preamp should provide zero gain - correct?  The amp will always provide gain - that's it's purpose.

Bryan

As you know, if we take the source's output, we need x amount of gain for our system to reach full volume.
Traditionally part of the gain was in the active preamp (which provides switching and volume control) and part was in the amplifier.
Now many companies are putting all of the gain in the amplifier, which is now an integrated amp by definition, even though it may not have source switching or a volume control. Many companies try to lead us to believe they have eliminated a gain stage because no active (gain) preamp is required, but the gain is in the amplifier. How good is the added gain stage(s) compared to a good active pre?
Same with the source, say a CD player that puts out 2 volts, if the gain in the output is eliminated we now need an active preamp to drive the amplifier to full power, again how good is the extra gain in the CD player compared to an active preamp?

Lin


Steve or anyone, feel free to point out any errors (if any) in the above comments.

[richidoo]

Can the "integrated preamp" contained in a modern power amp provide as good signal as a dedicated pre when it shares its power supply with the output stage which is optimized for power? I guess they know what their doing, some modern amps sound pretty darn good 

Digital amps are interesting in this because they draw the high voltage speaker level waveform using the output device. Voltage and current created simultaneously, at least that's how I understand Hypex to work. There is an input buffer though.
Rich

[stereofool]

For this reason I like it when reviewers* and forum members, that seem to have similar tastes as myself, have the same amp/speakers/CD player/preamp (pick one or two) as myself. Then when they try new components with the one that I own, their experience can help narrow down the field for me and it may just be a placebo, but it has worked out good more often than it has failed.


I see this as one of the true values of our forums  ! Especially when you know how one (or more) of our members 'hears' what they are listening to. This knowledge can help one build a list (or weed one out) of possible candiates, for new equipment or accessories.

Maybe even limiting 'Nervosa' and potentially finding 'Nirvana'  !

[WEEZ]

A real purist approach, is to have as few gain stages as necessary to achieve the desired volume with the speakers you own in your listening space. Usually, this means a total of around 32-35db (certainly no more than 40db). Usually, this can be accomplished with (3) stages. It is desireable to have the first stage (pre-amp) separated from the driver stage and output stage with it's own power supply to minimize feedback; distortion; and other nasties, as Steve pointed out.

What I was pointing out (I think) is that in most of today's equipment, we are getting high gain from our digital source (some dacs put out as much as 8 volts; at least 2V) and from amplifiers that have as high as 30db of gain in and of themselves (requiring only maybe .7V to 1V to reach full power). All or most of the gain is in the wrong place, and maybe not of the highest quality

Regardless of that, however, and IMHO, a pre-amp is still beneficial in that it 'conditions' the system and drives the cables and amplifier much better than a CD player or dac can. (or a tuner or video player or tape deck, or even a phono amp)

Ralph Karsten's amps (Atmasphere) for example, have only one gain stage. I'm not sure about Steve's amps...but my guess is that they have only one also. Gain is added in the (separate) preamp.

Most of us who use preamps don't need all the gain they provide....but the system benefits from the buffering and current- drive they provide.

My amp has around 26db of gain. It will play loud enough with my CD player and a passive volume control. However, the performance is not satisfactory. Tonally, it was okay..not great, but okay. But the system lacked dynamic ability and definition. For background music it would have been okay. But there was simply no 'life'. There is no way I would give up a preamp. (Besides, I have multiple sources, so I'd need a selector anyway)

WEEZ

60db Rich?   Nah......

[opnly bafld]

Very nice post WEEZ.
Digital devices IMO could sound better if they had less output and left that to a preamp.
I don't, for the most part, think that will happen (although there are a few that have less than 2v).

Steve's amp has 2 gain stages, requires 3.5v to reach full power and provides approx. 12 dB of gain.

Lin

[richidoo]

Yup, 60 is a lot. I was including the gain in the source output stage because Steve had mentioned that is misplaced. Obviously 26dB power amp and 20dB preamp is a lot of gain already.

I get a pretty nice presentation, tone, dynamics and aliveness with no preamp. I have had active preamps in the system and they sometimes add positively, sometimes negatively. It is a slight coloring at most. Stereofool's AR Ref 1 has been the nicest visitor yet. The big change is when a good source is put in place of my stock SB.

[steve]

"Can the "integrated preamp" contained in a modern power amp provide as good signal as a dedicated pre when it shares its power supply with the output stage which is optimized for power? I guess they know what their doing, some modern amps sound pretty darn good"

See my theory page http://www.sasaudiolabs.com/theory8a.htm
"Interstage Sonic Feedback Thru the Power Supply"

With more stages in the amp, integrated amp increases the feedback problem through the power supply between more stages. Placing more gain, more stages in the preamp gainstage automatically causes more problems as well. Sharing seems to be the best solution.

Think this. Lower the gain in the integrated amp by eliminating the preamp stage and dedicating its own high quality power supply, with no compromises. Now eliminate the crappy analog stage from the CD player. What do we have?
One added a super quality preamp stage, one less crappy gainstage in the amp, and one less crappy gainstage in the dac or player. Overall, one less stage of gain with the other gainstage with better quality.

Lin explained things quite nicely.

"You really are a voice in the wilderness though aren't you?"
Well I guess so. I don't know if manufacturers just didn't think things through, or whether the bottom line was more important.

"Digital amps are interesting in this because they draw the high voltage speaker level waveform using the output device. Voltage and current created simultaneously, at least that's how I understand Hypex to work. There is an input buffer though.
Rich

Just be careful of any interference generated? My understanding is that many, if not all brands of digital or pulse width modulation, had real problems with interference getting into all components in the audio system. Imo, unless they can get the problem under control, I would avoid them like the plague.

Ps. Make one or more components adjustable, so one can have what they want. Neutral/organic for some, even more organic for others, leaner for others. It is a win situation for most consumers. Vauhn amps do this as well as my test amp (which hasn't been sold in 4 years). Maybe others do as well.

Rich, 60 db is rather high and one would have multiple stages in the preamp, so the same frequency dependent feedback power supply problems would result as if they were in the amp. Share the gain, so maybe 14db gain or so in the amp, 23db in the preamp, none from the dac if possible. That way, the physical size of each component remains manageable, each stage can have its own power supply, and each stage of gain is optimized. Just a thought.

[miklorsmith]

Let's see - wire test.  I did mine straight from the source to the Red Wine amps, which have dual DACT attenuators.  Since the 11A sounds like "nothing", I would think this a valid test.

It's interesting to me that the overall tone is leaning toward "the unfiltered truth is better" side, with the alternative being syrupy coatings which necessarily obscure detail.  Tone and detail are not mutually exclusive.  A speaker cable comparison may exhibit this dichotomy but don't assume this is a universal rule.

Of course going too far into euphony will create this result.  As I have observed previously, depending on which DAC I'm using, I may favor a different equipment arrangement even using the same cabling and speakers.

I agree with Brian's observations completely.

I spent a good amount of time with a $200k system comprising near-zero-distortion components and speakers.  The result was sterile and completely unhuman.

I had a preamp with no voice for about 2 years.  What I found was that the amplifier alone was insufficient to get where I thought the appropriate degree of saturation was for my system.  Going back to a color-enhancing tube preamp has brought "the love" back in spades and I couldn't be happier.

[bpape]

Tone and detail are not mutually exclusive. 

Amen.  That's the trick in my mind.  Get something that still gives you the detail you want (but not unnatural detail) and still provide the smooth, somewhat warm sound that you get from a live session.  Have you ever heard a sterile, cold, uber-detailed live performance?  I haven't.  Live music has soul and body as long as it's not being performed in a glass room or something silly like that.  Unfortunately, most commercial recordings don't capture that - a very few do.

Now, if someone could come up with a 'warm' tone control that'd be the ticket. 

Bryan

[steve]

"It's interesting to me that the overall tone is leaning toward "the unfiltered truth is better" side, with the alternative being syrupy coatings which necessarily obscure detail.  Tone and detail are not mutually exclusive.  A speaker cable comparison may exhibit this dichotomy but don't assume this is a universal rule."

"Of course going too far into euphony will create this result.  As I have observed previously, depending on which DAC I'm using, I may favor a different equipment arrangement even using the same cabling and speakers."

I agree, it depends on the amount of coloration.

"Let's see - wire test.  I did mine straight from the source to the Red Wine amps, which have dual DACT attenuators.  Since the 11A sounds like "nothing", I would think this a valid test.

How did I know with such certainty that you would use this procedure? Anyway, the way you performed the test is not an accurate test. I know you don't understand why, but it would be better if you just let it go.

"I spent a good amount of time with a $200k system comprising near-zero-distortion components and speakers.  The result was sterile and completely unhuman."

Two comments. One, what is your definition of sterile? I like my instruments/voices to sound real, just as if one were present. Of course, many CDs/players won't give that sound. But that is my goal. I find nothing sterile about a live conversation.

Second, if the $200k system sounded sterile, either your definition is different than mine, or the system is not accurate, and is actually not a "wire" with gain. Remember, they also just 'voice', so they can be off just as much as any other component.

"I had a preamp with no voice for about 2 years.  What I found was that the amplifier alone was insufficient to get where I thought the appropriate degree of saturation was for my system.  Going back to a color-enhancing tube preamp has brought "the love" back in spades and I couldn't be happier."

I am glad a "colored" preamp brought your system back to life. However, you actually have no fool proof way of knowing if the preamp had "no voice", the rest of your system is off, or if the preamp with no voice was actually sterile with your replacement actually being correct; since you have no foundation, any fool proof reference to rely upon.

Ps. Bpape, I think we are thinking the same thing. Natural, detail yet organic as well.

[miklorsmith]

All the earlier comments were that listeners couldn't tell whether the 11A was in the system or not.  If it sounds like "amp direct", that's no sound and my test was fine.  Your response here is extremely condescending.

My previous pre was a TacT, digital-out to a few different DACs which drove the amps.  Everything "worked" perfectly, but overall I needed more color.

According to the Stereophile measurements, the Lamm LL2 Deluxe has a noticeable 2nd order harmonic distortion presence into a 20 Kohm load, which the RWA amps are.  Into higher impedances typical of tube amps, distortion goes down significantly which theoretically would get the pre more out of the way.  It seems this way to me, going between the Red Wine and Yamamoto SET amps.