[Steve]

The stereo world has been without direction for a very long time.
Let's take an in depth look at each component and see the state of affairs. I won't list every type, but in general.

1) CD players have an output of approximately 2 volts, largely due to
an analog stage with a gain of approximately 2, or 6db. A whole stage with only a gain of two. There are several types.

 A. Op amps with huge amounts of negative feedback, and cheap parts, about $1.99, if that. That is not kidding.

 B. Discrete parts, feedback or not, about $2.99, if that. Again not kidding.

 C. Tube analog stages. Probably better than options 1, 2 but not nearly enough physical room to design a great accurate, natural analog stage.

 D. Many use electrolytic capacitors for coupling capacitors.

The thing is the analog output of the digital to analog output chip (DAC chip) is already 1 volt. So why add an extra cheap stage, a bottleneck, to one's system?
And why spend 10 grand on the rest of the system with a $3.00  bottleneck in the CD player?

2) Preamplifiers, like any other stage varies in quality. However, the one advantage a separate has is that it has its own power supply. This basically prevents frequency sensitive musical feedback from stage to stage through the power supply or through any common wires to two stages.

For those skeptical, use a 6 inch piece of 20 gauge wire as common ground between two component's inputs, say player and tuner. The tuner will "bleed" into the other input. Decoupling filter capacitors are much worse than a 6" piece of wire, and are frequency sensitive.
Think of the delicate harmonic structures being degraded.

3) Integrated amplifier. Sure one gets rid of an IC. However, the problems associated with a common power supply, feedback, imperfect grounds (bleeding) etc, see previous points, cause some real problems.

Speakers are all over the place, with a seemingly infinite varieties of frequency responses, powers, dispersion characteristics etc.

The solutions are, eliminate unnecessary stages. Use only necessary well designed stages.

Isolate each stage as fully as possible. This means separate power supplies (including transformers), minimizing the length of all common grounds and parts between multiple stages.

The above points are not easily, or cheaply accomplished, but necessary if optimum, natural sound is to be achieved.
I believe some standards should also be changed, such as using 1 volt analog output rather than two volts output, as this will eliminate the cheaply designed analog gainstage mentioned above.

One more point. DAC chips are usually if not all class B pushpull output. Make the chip a little larger and run class A single ended. This would eliminate the push pull and the phase splitter stage.

The audio scene could be cleaned up for better sound.

Cheers.

[roymail]

All I know is what I have experienced.  My nicely modded cd player > Goldpoint/Elma stepped attenuator > amplifier > 92db sens speakers... sounds better than using any average priced preamp.  I still have one but I don't use it.

Perhaps high end, expensive preamps will likely sound better.  However, for me in my situation, I'd rather upgrade either my source, amplifier or speakers instead.

[Steve]

Perhaps high end, expensive preamps will likely sound better.  However, for me in my situation, I'd rather upgrade either my source, amplifier or speakers instead.

Of course, completely understandable; didn't mean any offense. Practical considerations are prominent.

I think it is beneficial to explore the pros and cons. The more knowledge, the more power one has.

Cheers.

[doug s.]

All I know is what I have experienced.  My nicely modded cd player > Goldpoint/Elma stepped attenuator > amplifier > 92db sens speakers... sounds better than using any average priced preamp.  I still have one but I don't use it.

Perhaps high end, expensive preamps will likely sound better.  However, for me in my situation, I'd rather upgrade either my source, amplifier or speakers instead.

Of course, completely understandable; didn't mean any offense. Practical considerations are prominent.

I think it is beneficial to explore the pros and cons. The more knowledge, the more power one has.

Cheers.

yes, practical considerations are prominent.  but roy, i am not sure what you mean by average priced preamp vs expensive high-end preamp.  i guess it depends on your budget.  but, ime, you could spend as little as $500, if you are willing to consider used equipment, and have a preamp that will make a significant improvement to your system.  one that will make an appreciable improvement to any other source/amp/speaker upgrades you may then make.  up the price to $1k if you are wanting more features/inputs/etc...

doug s.

[roymail]

I don't take issue with anything here since I don't have nearly as much $$$ invested in audio gear as most of you.  As I said before, there is always something that sounds better than what we have.  For now, I'm listening more to the music and paying less attention to my gear.

However, if I hear something that knocks my socks off and can afford it, things may change.  A man's got to keep his options open... right?

[JoshK]

My $.02....tifwiw and all that...

I think most preamps have too much gain, any more than 6db (12db is pushing it) and I think you have too much unless your speakers are <85db or you listen room is a stadium.   I think the real benefit of a preamp is in current delivery and impedance matching.  Hence a good buffer with switch and volume should suit most folks.

[Steve]

May I again suggest ridding of the gainstage in the CD player. Afterall it is the cheap bottleneck and only 6db of gain, which is basically worthless.

Are you referring to a buffer with no gain, or one with gain yet low impedance? Anyway.

I would prefer a setup with minimal analog stages. For a true example, a CD player (minus the cheap analog gainstage), preamplifier and amplifier with a grand total of three analog stages. Of course one or two high gain stages is needed, in preamplifier or amplifier or both makes no difference.

I don't think one wants the volume control at 9am, nor at 2pm (with lowest high frequency response).

Output Z of CD player is a few hundred ohms (with impedance and voltage protection), output Z of the preamplifier 3k ohms ok, so no need of low output impedance cathode follower.

If some think 3k ohms output Z is high, with 50pf IC the high frequency response drops by approximately .045db at 100khz and   .0015db at 20khz.

With 200pf IC, the high frequency response drops by approximately  .6db at 100khz, and approximately .03db at 20khz. However, I don't wish to go higher than 3k ohms.

Cheers.

[JoshK]

My particular DAC has a current output DAC, not the typical delta-sigma voltage output.  Thus it takes a transconductance stage, which is all discrete.  So my case is not necessarily everyone else's.  I do concede your point about generic CD players.  I am not sure that fits most of folks cases these days.  DACs seem to be more popular nowadays, but many still have opamps I am sure.

Are you referring to a buffer with no gain, or one with gain yet low impedance? Anyway.

I was suggesting one doesn't typically need gain, so buffers work fine in many cases.

[Steve]

My particular DAC has a current output DAC, not the typical delta-sigma voltage output.  Thus it takes a transconductance stage, which is all discrete.  So my case is not necessarily everyone else's.  I do concede your point about generic CD players.  I am not sure that fits most of folks cases these days.  DACs seem to be more popular nowadays, but many still have opamps I am sure.

I was suggesting one doesn't typically need gain, so buffers work fine in many cases.

Yes, you make a good point, DACs are often used and your design would not allow such. I would also bypass the analog stages in Delta type DACs, even when built with discrete parts, since the gain is only two (6db), and the DAC chip has an output Z of less than 10 ohms. (Of course I can see the need if the particular circuit design needs one to work properly.) I have found the current is plenty to drive ICs into a preamplifier/amplifier input.

I can understand adding a buffer stage when using transistors and if the output Z of the tubes is very high, such as with 6CG7, 6SN7, 12AU7, 12AT7, 12AX7 etc type of tubes (Check Rp of a particular tube type, then add cathode resistor times the Mu to Rp (if the cathode resistor is not bypassed)).

However, although adding a buffer stage increases high frequency performance, the buffer still deteriorates the sonics in and of itself (there are lots of parameters to deal with and no stage is perfect by any means), such as allowing frequency sensitive musical feedback to occur through the power supply itself.

Cheers.

[roymail]

Steve, what would be your preference for a single source cdp setup with volume control?

[Steve]

Steve, what would be your preference for a single source cdp setup with volume control?

I have none.

Cheers.

[FullRangeMan]

I have none.

Cheers.

One time I see a repair tech using a CD player direct on the tube power amp and driving a low sensitive Avalon speaker, there was no volume control.

You run something like this??  or use a integrated ?

[Steve]

One time I see a repair tech using a CD player direct on the tube power amp and driving a low sensitive Avalon speaker, there was no volume control.

You run something like this??  or use a integrated ?

Hi Gustavo,

Interesting comments/questions. I have been designing for some 40 years (50 years total). Also worked in RF, consulted professors over a portion of that time, and never ran into a scenario you have described. By not using a preamplifier, or necessary gainstage, the tech's system lacked the necessary gain.

My CD player output is 1 vrms. My preamplifier has approximately 21db of gain. The first stage of my two stage amplifier has approximately 15db of gain and drives my output stage. Speakers are Phast Jr. with sensitivity of approximately 89-90db. My volume controls are usually set around 10-11 o'clock.

Total of three gainstages, no buffers.

I hope I have answered your question satisfactorily.

Cheers.

[FullRangeMan]

Thanks Steve for your detailed reply. This image are the system I refer, from Mr.Richard Kern, at an PFO test, a VT100 + Avalon Arcus.
Regards, Gustavo

> Never go to a psychiatrist, adopt a cat or dog from the street. On the streets pets live only two years average.