[ehart]

In my system, I have used both balanced and unbalanced, and can't hear a difference.  I now have about 40' between preamp and amp, and do use balanced connections there, and am glad that I have the capability.  Some of my gear has to be in the basement (amps) to make room for everything.

This is something of a religious issue.  Some people claim that unbalanced connections can be made to be more "direct" (simpler) electronically, and therefore theoretically better sounding if interference is not an issue.  Others (seemingly quite knowledgeable) say that properly made balanced connections can be just as direct as unbalanced.

All things considered, I'd rather have flexibility and be able to choose, particularly with separates where you might want to tuck the amps away. 

With an integrated, though, it's not likely to be an issue -- you aren't going to put your integrated into the basement, and you're going to keep it near your sources, so you can see the display and press the buttons.  And I don't know of any sources that support *only* balanced connections (of course, there are probably some out there).

Best,

Eric

[Carlman]

IN YOUR OPINION....

Very few amps (Quicksilver Horns and Cary Rocket 88 are the only ones I can think of) require a pre amp at all – a pre amp with gain is superfluous at best.  A pre amp in a modern system is just going to add noise and a sonic signature. The signature may be pleasing but if this is the case, by definition, the amplifier has something undesirable about its sound so why not just replace it?  IMO this defeats the flexibility argument as well – tailoring your sound is cheaper and easier when you are only replacing one component (and don't forget the whole cable thing). 

 
So, based on your (seemingly) cursory knowledge of hifi, there are a lot of people chasing their tails in this hobby.

Integrateds also have sonic signatures.  Sometimes there's a simplistic (yet cheap and coloring) preamp section on an otherwise good amp that clouds the presentation. 

The flexibility of an amp and preamp at least provides some knowns in getting a good match.  When you buy various integrateds, you don't really know what they've done or how it will sound.  But it will 'sound' like something.

Whether you're buying an integrated, a preamp/amp combo, or building a passive to go with an amp, you'll still have to decide which "sound" sounds best to you.  Lately I've really been enjoying the 'McIntosh' sound.

McIntosh has a new integrated out with a phono input that I was seriously considering but then stepped up their chain quite a bit and bought an amp to pair with my TacT preamp/DAC.  I'm now considering going 'all the way' with a McIntosh preamp... we'll see.  However, the TacT is likely a technically better preamp than the Mac but I think I like the 'coloring' effect of tubes.

[dado5]

ntegrateds also have sonic signatures.  Sometimes there's a simplistic (yet cheap and coloring) preamp section on an otherwise good amp that clouds the presentation.....

Yes they do. But you have only one to worry about.

Integrated amps do not contain more amplifying stages than power amps in general (my memory is that SAS took out the voltage stage in his amps but I am not positive as he no longer has them on his site...and this is what Cary does with the 88). The cheap voltage stage problem would be an issue either way and the addition of another, external stage is not going to solve it. It may mask it, but then this goes back to my original point - why not just buy an amp that sounds better?

It's important to keep in mind that with most volume controls, the signal is attenuated  more than 10 times under 11 o'clock and does not get to half level until around 2 o'clock. In other words if your system is too loud at 2 o'clock or earlier, you require less than half the signal your source is putting out to get the volume you need.  It is in this high attenuation range that volume control noise is highest and tracking is poorest.

[WEEZ]

While I agree that many systems play loud at modest volume settings..this isn't unique to separates. Many integrated products are the same way. Most have more gain than is necessary for most home environments. Gain is gain- whether it comes from a 3 stage integrated or separates. That has nothing to do with the original poster's question, anyway.

Today's cd players may output enough voltage to drive a power amp directly...but few output enough current. A passive box won't help that situation. If a system has too much gain, then an active pre-amp with low (or zero) gain is a better solution than a volume pot in a box.

I agree that an integrated is easier to implement, but a good one isn't cheap. There is no free lunch.

[G Georgopoulos]

In terms of amplifiers in the two-channel audio setup, what are the real pros (and cons, if any) of separated preamp and poweramp.

------------------------------------------------------------
components/separates in my opinion offer higher quality sound
with components you get to listen to whats best and what
you like it is also easier to customise and build up a quality
music system combos dont offer this and thus are regarded
mid-fi

in years past components were popular nowadays you can
only find them in high-end stores costing $$$$s

i think components should be the only choice for a serious
music lover who wants to listen to the best two channel stereo
can offer

i am for components 100% for sure!!

regards

[dado5]

While I agree that many systems play loud at modest volume settings..this isn't unique to separates.

Sorry if I was not clear here.  I am not saying that integrateds do not have a gain issue, rather that a separate active stage only adds gain where usually none is needed. IMO this is one of the main problems with separate pre-amps (especially tubed ones).

Current would only be an issue if the impedance of the amp was not sufficiently greater than the output of the device as then the interface shifts from voltage to power transfer. This may be a problem with a tubed output stage but that's about it.  Passives can be a problem here as well if the amp input impedance is on the low side as many solid state units are. That's why they are a last resort  in the case of absolute love for a given amp (and even here super low impedance units or transformer volume controls should work fine).

[Steve]

Of course, I prefer separates. But they can be more expensive and require more time to obtain the proper components.

Also, unless the integrated has an inboard volume control (possibly more hum), one loses the advantage of fewer ICs, and may expend more money for a volume control device. Thus cost may not be such an issue.

An "integrated amp", by definition, has a preamp stage combined with the basic amp. (Check articles in Library of Congress, Stereophile magazing etc.)

Thus an integrated amplifier has more stages than a basic amplifier. This causes problems when a common power supply is used for two or more stages (typically the case).

I removed the first stage from my amps (when I get a descent chassis, and time, I will again offer an amp. Right now, my test amp has two stages) and made a separate preamp.

I have found that to manufacturer the best preamp stage, one needs alot of space, which could not be incorporated into any integrated amps I have seen. The same appears to be true when incorporating a tube analog section into a CD/DVD player.

Separating the preamp from the amp has several advantages over integrating.

1) No signal/musical frequency dependent feedback/mixing between the amp stages and the preamp stage(s). On integrateds, this type of feedback can be seen using an oscilliscope. I have an article on the subject at: http://www.sasaudiolabs.com/theory8a.htm .
(I tried to make the article easy to understand.)

2) A: Let me mention first; normally an integrated amp comes into existence by designing the output and driver stage(s) to match a given speaker. Then the "preamp" stage is designed to compensate for weaknesses in this "basic" amp/speaker combo.
This causes problems in that the speaker and amplifiers are both variables. (I say the amp and speakers are each variables in that there is no way to directly check each for neutrality, VS a straight wire.)

Who knows how good each is? So now we have three variables, the "preamp" stage, the amp stage, and the speaker. None of the three is neutral as they should be, so trying to obtain synergy is very difficult.

The other way for a manufactuer to create is to design the preamplifier to sound like a straightwire (a stage that can actually be compared to a straightwire). Thus the preamplifier stage is Not compensating for any weaknesses of the amp and speakers. So one less stage to deal and worry about when choosing an amp and speaker.

Now the amplifier and speakers are designed to match the preamplifier. As a manufacturer, comes the back and forth routine of continuing to "tweek" the source, amp, and speakers until optimum sound of the audio system is achieved. I believe this results in a preamp, amp, and speaker combo that has better synergy, with less and fewer weaknesses and more strengths, thus more involving sound.

One thing I have noticed is that feeding a signal from a separate excellent preamp into an integrated amp "input" (usually tube) almost never sounds great. This is because neither the "basic" amp nor the preamp section of the integrated are designed to sound like a straightwire. The internal preamp is off, compensating for a flawed "basic" amp.

Of course a customer will probably not be able do the above procedure as a manufacturer does. But the crucial point is to start with a separate, excellent preamplifier. This gives the customer a head start in achieving a better system by demoing his preamp with different combos at the audio store. IMO, starting with the opposite, the amp/speaker combo and then the preamp will lead to dissatisfaction.

[WEEZ]

Steve,

I don't argue with any of what you posted. Indeed, separates are usually best, and I happen to be in the preamplifier camp.

I would appreciate your 'take' on the gain issue. Let me preface this by somewhat agreeing with dado5. Most amplifiers have anywhere from 20 to 29 db of gain. Add to that the gain of a preamplifier with anywhere from 12 to 23 db of gain; and the control over volume can become an issue. (i.e., 9:00 on the volume pot and the system is too loud). That is probably the reason for the popularity of 'passive' pre-amps. I read somewhere, that 32db of total gain is more than enough for most systems in most rooms.

In my case, my amp contributes 26db and my pre-amp another 12db. I can only use about half of my volume control before I go deaf! In another thread, you commented about an amplifier (Pass) that sounded good with your 11A...and the gain seemed real high, according to the specs.

Comments?

WEEZ

[Steve]

"I would appreciate your 'take' on the gain issue. Let me preface this by somewhat agreeing with dado5. Most amplifiers have anywhere from 20 to 29 db of gain. Add to that the gain of a preamplifier with anywhere from 12 to 23 db of gain; and the control over volume can become an issue. (i.e., 9:00 on the volume pot and the system is too loud). That is probably the reason for the popularity of 'passive' pre-amps. I read somewhere, that 32db of total gain is more than enough for most systems in most rooms."

>>There are several issues that could be dealt with in my reply, but I will try to keep it simple.

>>Yes, I also agree, there is too much gain. I would hope that Pass could eliminate a stage of gain as the 350.5 would sound even better if they did. However, that is unlikely. Luckily the Audio Aero had its own internal volume control, which we used to lower the output from the player. (By the way, the Audio Aero sounded quite good.)

>>One plus of having the volume control set lower, say 10 o'clock, is that the frequency response is relatively high. At 2 o'clock, basically mid resistance position, the high frequency response is poorest. As we rotate past 2 o'clock toward max volume, the high frequency response will normally rise again. 

>>I also wish CD/DVD players had output jacks so the dac output could go directly to a descent analog preamp instead of the cheap designs inside, whether tube of SS. (There just isn't enough room to design the best tube section.) Then another analog stage, within the CD player, could be eliminated as well.

>>Even eliminating one, but preferably both stages, would lower gain and improve the quality of the music being presented, and eliminate some feedback through the power supply.

"In my case, my amp contributes 26db and my pre-amp another 12db. I can only use about half of my volume control before I go deaf! In another thread, you commented about an amplifier (Pass) that sounded good with your 11A...and the gain seemed real high, according to the specs.

Comments?"

>>Luckily the Audio Aero had a volume of its own and we could also use it and still obtain excellent sound with the Pass while having descent rotational ability. There just isn't much one can do when manufacturers continue to run the gain out of sight in players and amps. Even the RCA Radiotron Designers Handbook speaks of the problem of feedback through the power supply, decades ago.

>>As far as gain and stages, it is true one can run only 3 total stages using high gain tubes like 12AX7s and 12AT7s etc and have ultra gain. But one consequence is that the gain bandwidth product is very poor, meaning the high frequency response is not very good, although the gain is high.

>>Still, one could use separate power supplies and improve the sound, similar to separate components, but in one chassis. However, very very few companies do because of expense and physical size limitations. Price points seem to dictate.

>>If you have a tube amp, you could try by passing the first stage and feed the music into the second. However, if DC is present, a capacitor maybe needed to prevent DC from the new  input jack. (Also, BEWARE there are high voltages that can kill, so be careful or let a qualified technician do the work.) If the "preamp" stage is compensating for problems in subsequent stages, the sound may actually be worse with a good preamp. In such case, I would just leave it alone and enjoy, or else purchase a better amp.

Hope this answers some of your questions Weez. If unclear, let me know.

[Robert57]

This has been a great thread-- I especially appreciate Steve's comments. I just learned of a Conrad Johnson SS integrated , the CA200, which C-J classifies as a "control amp" because it combines a good passive stepped attenuator volume control, with input switches, in lieu of a full preamp gain stage. The amp module is based on the 350 Premier, which has received some excellent press. Assuming one has enough gain overall from the source, and one likes the overall sound of the amp, what do you guys think about this as a compromise? Kevin Haskins (DIY Cable) also has announced he is planning to add a Bent TVC into a Class D Ucd integrated stereo amp soon.

I had been considering getting a TVC preamp (like the Bent TAP or a Promitheus) in front of a fine power amp for minimal color and best transparency, and best drive at low listening volumes. But having the passive resister-based volume control hard-wired right to the amp might well be more transparent and less colored than an extra I/C (not to mention cheaper) to a separate pre. It also might suffer less volume or gain loss.

If the passive pre in the C-J, or some such well executed "control amp" design, were really neutral, could I add a tubed pre in front of the integrated/control amp for desired romantic color if I so desired, without muddying up the sound? I could potentially use the remote on the integrated for overall volume control. Or would the stepped or ALPS attenuator in the control amp cause too much loss of drive and dynamics, or just too cluttered a signal path,  if I were in the 12:00 or lower volume area? I had been under the impression that a separate TVC (to a power amp) might be a better passive pre overall, with its better impedance matching and drive at higher attenuation (compared to a POT or resister-based passive). I like the idea of being able to have a totally neutral pre (like a passive or superb tube pre) for most uses but also have the ability to add or swap in a warmer tubed pre for color, depending on the music. Unfortunately, I may need the extra gain of a separate preamp anyway since I have a Bolder modded SB2 as my main source, with only one 1 volt output.

Thanks.

Rob

[WEEZ]

Steve, thanks for your insights..

Rob, I'm not sure I follow your theory of possibly adding a tubed pre-amp for 'color'; a good pre-amp whether sand or glass, won't (or shouldn't) add color.....

WEEZ

[dado5]

Thanks for coming into this discussion Steve.  I'm glad I did not mis-represent your design in my post.

I have to disagree though -At least in the tube world, most integrateds and power amps contain the same number of stages.  This is because cost effective single-ended designs require 3 stages to drive a speaker and PP's require 3 or 4.  The voltage gain inherent in these designs  (either WE or Williamson variants for the most part) is more than enough for a modern source.  Integrateds from companies like CJ, AR, VTL/Manely, Cary are the same topology as their  power amps - indeed Rogue Audio's integrated and stereo amps are identical circuit wise.

But to the main point, a pre-power amp combo is hampered by the gain issue almost as a matter of course and this is one more point in favor of integrateds IMO.  Steve's very well received products are an exception but if his pre is mated with another brand amp,  the gain issue could well remain.

Thanks,
Rob

[Steve]

Hi Rob,

   I have seen PP amps with as many as 5 stages. 3-4 seems common when using the typical phase splitter and high gain tubes like the 12A t or X 7 type tube.

 IMO, even a 3 stage SE needs to at least use separate supplies for each stage.

As far as CD players, I will wish till my dying days that they would just get rid of the cheap, poorly designed analog crap stages, period.

[WEEZ]

Steve (or anybody),

In the old days before digital, a typical FM tuner or tape deck would put out 500mv-1v. And a phono stage was similar or maybe lower (5mv cartridge w/ 40db gain = approx. 500 mv output). So what's with the 2v output from digital players anyway?

Maybe today's pre-amps should provide 4X gain (around 12db) on all but the cd input; and on the cd input- just a buffered 0 gain thru-put. Then all sources would provide the amp with approx. 2 volts. Am I missing something? 

WEZ

[Steve]

 "Maybe today's pre-amps should provide 4X gain (around 12db) on all but the cd input; and on the cd input- just a buffered 0 gain thru-put. Then all sources would provide the amp with approx. 2 volts. Am I missing something?  "

I know what you mean, but I still would rather get rid of the analog stage in the player and run the analog into a top notch preamp. Many if not most of the CD designers are objectionists, so parts and design quality is minimal.

Maybe I should try that sometime and see what happens?

[Kevin Haskins]

I wish I had the time to design a DAC.   I'd design something with a USB input for computer based interface along with the typical S/PDIF interface.    I'd use a couple S&B transformers for the buffer and to give it a balanced output.    Run that into the S&B TX-102s and into the Hypex UcD and you would only have one active gain stage between the DAC & the output stage on the amplifier.   The noise floor would be through the floor and with the right parts & power supply design it would sound freaking incredible.

[dado5]

n the old days before digital, a typical FM tuner or tape deck would put out 500mv-1v. And a phono stage was similar or maybe lower (5mv cartridge w/ 40db gain = approx. 500 mv output). So what's with the 2v output from digital players anyway?

That's part of the reason some of the 50's vintage amps had lot's of stages - Eico and Grommes come to mind - the other was to recover from high levels of feedback.  Genelex, Dynaco and especially the Quad were really elegant in their compactness though. 


Some of the NOS DACs have no analog stage, just passive IV conversion and Cuffoli has some transformer  direct out projects on his site.

http://www.audiodesignguide.com/mydac.html

[dado5]

Steve,

You really hit a good point with the separate supplies.  I did that for my amp (2 stage xfmr coupled 300b) not to long ago and it made a very noticeable reduction in noise - not hum as much as the tube 'rush' type noise.  Why do think it makes this kind of difference?