Adding a pre amp

[barrows]

13 minutes ago, diecaster said:

The bottom line here is that guys with a ton more experience than you think active preamps sound better than passive/none. I am not telling you that you have to like active preamps. But crapping them makes no sense. My 40 years of experience is audio sides with Pass and BHK. 

You are drawing the wrong conclusion from what Mr. Pass said.  He is not referring at all to DACs or going DAC direct to amplifier, he is talking about an active volume control circuit vs. a fully passive solution.

 

A DAC direct connection to an amplifier is NOT a passive solution.  The DAC has an active buffer circuit at its output, just like the active preamp Mr. Pass is referring to, so it can drive the cable and input stage of the amplifier correctly.

 

I have plenty of experience with active preamps, I kept an active preamp in my system, and compared with going DAC direct to amps, until the point at which the DAC direct connection outperformed using a preamp in every way, then I ditched my preamp.  I will never go back, even if I add a turntable back into my system.

 

Again, I have nothing to gain by my advice here, but I would be cautious about advice coming from those who would like to sell one another expensive component.

[diecaster]

6 minutes ago, barrows said:

You are drawing the wrong conclusion from what Mr. Pass said.  He is not referring at all to DACs or going DAC direct to amplifier, he is talking about an active volume control circuit vs. a fully passive solution.

 

A DAC direct connection to an amplifier is NOT a passive solution.  The DAC has an active buffer circuit at its output, just like the active preamp Mr. Pass is referring to, so it can drive the cable and input stage of the amplifier correctly.

 

Pass is not talking about DACs at all. Part of what he says is talking about issues that are well understood. Then you have this quote:

 

Then there are things that don't show up in the usual measurements and we simply observe that the active circuit sounds better than the passive.

 

I file these under "How About That".

[Fluffytime]

I'd like to know who died and made Nelson Pass "God Emperor of Everything".

 

(argument from authority is such a cute fallacy)

[pkane2001]

3 minutes ago, Fluffytime said:

I'd like to know who died and made Nelson Pass "God Emperor of Everything".

 

(argument from authority is such a cute fallacy)

 

I like Nelson’s commercial and DIY designs, have owned (and still do) multiple amps by him. But I still miss the part where he says that a preamp is better than no preamp.

[barrows]

9 minutes ago, diecaster said:

Then there are things that don't show up in the usual measurements and we simply observe that the active circuit sounds better than the passive.

You are still not getting it. 

 

What Mr. Pass is saying that it is (generally) better to have an active circuit driving the (cable and the) input of the amplifier.  This is exactly what going DAC direct does!  The output of a DAC is an active buffer circuit (in all but the most obscure designs).  This has nothing to do with measurements (or not measurements): the point is, the output circuit of a DAC is the SAME as the output circuit of an active preamp.

[Fluffytime]

5 minutes ago, pkane2001 said:

 

I like Nelson’s commercial and DIY designs, have owned (and still do) multiple amps by him. But I still miss the part where he says that a preamp is better than no preamp.

 

Yeah, I've owned a Pass desingned amp, and I thought it sounded great. Massive kudos for Pass.

 

I just can't get on board with the deification of an audio engineer, no matter how good their products are.

[Panelhead]

1 minute ago, barrows said:

You are still not getting it. 

 

What Mr. Pass is saying that it is (generally) better to have an active circuit driving the (cable and the) input of the amplifier.  This is exactly what going DAC direct does!  The output of a DAC is an active

1 minute ago, barrows said:

You are still not getting it. 

 

What Mr. Pass is saying that it is (generally) better to have an active circuit driving the (cable and the) input of the amplifier.  This is exactly what going DAC direct does!  The output of a DAC is an active buffer circuit (in all but the most obscure designs).  This has nothing to do with measurements (or not measurements): the point is, the output circuit of a DAC is the SAME as the output circuit of an active preamp.

buffer circuit (in all but the most obscure designs).  This has nothing to do with measurements (or not measurements): the point is, the output circuit of a DAC is the SAME as the output circuit of an active preamp.

Barrows you are being chummed. I think everyone knows your stance. One less active component and cable should be better. Only a poorly designed dac with volume control benefits with a preamp.

  My interface uses a FPGA to select digital inputs and analog outputs. Better than an analog switch.

  

[pkane2001]

6 minutes ago, Fluffytime said:

 

Yeah, I've owned a Pass desingned amp, and I thought it sounded great. Massive kudos for Pass.

 

I just can't get on board with the deification of an audio engineer, no matter how good their products are.

 

No deification here, although I do think he's perhaps one of the most creative and prolific designers working today. 

 

[Fluffytime]

14 minutes ago, pkane2001 said:

 

No deification here, although I do think he's perhaps one of the most creative and prolific designers working today. 

 

 

I agree with that, but there are people in this this thread (not you) who are trying to make the case that "Pass said X, so therefore X is a universal truth never to be questioned".

 

Which is just a massive logical fallacy.

[diecaster]

43 minutes ago, barrows said:

...the point is, the output circuit of a DAC is the SAME as the output circuit of an active preamp.

 

Ah, so all active preamps and all DACs have exactly the same output circuit. No, I didn't think so. That's why they don't all sound the same and that's why using an active preamp can sound better than using just the DAC.

 

Oh, and no, the output circuit of a PS Audio DirectStream is NOT the same as an active preamp.....

[wwaldmanfan]

I have used my system with and without a separate preamp and I don't hear much difference. The setup: NAD M51 single-ended out to > NAD power amp vs. NAD M51 balanced out to > Mark Levinson preamp single-ended out to > NAD power amp.

It seems to me, the better your equipment, the less you are going to hear small incremental improvements.

 

[sandyk]

1 hour ago, barrows said:

): the point is, the output circuit of a DAC is the SAME as the output circuit of an active preamp.

 

 A good quality preamp usually has a far better output stage than most affordable DACs, often using a discrete output stage, and quite often also uses higher voltage .+ and - supply rails (> + and -20V) than most  DACs. They often use Class A topology as well.

[sandyk]

22 minutes ago, wwaldmanfan said:

It seems to me, the better your equipment, the less you are going to hear small incremental improvements.

 

 That hasn't been my experience.

[TubeLover]

14 hours ago, barrows said:

Nonsense...  It does not require 5 figure DACs in order to employ a decent output stage capable of driving an amplifier directly.

In my experience it does. I cannot possibly tell you how many less expensive DAC's have  fallen short!

 

JC

[TubeLover]

9 minutes ago, sandyk said:

 

 A good quality preamp usually has a far better output stage than most affordable DACs, often using a discrete output stage, and quite often also uses higher voltage .+ and - supply rails (> + and -20V) than most  DACs. They often use Class A topology as well.

+100%

 

JC

[4est]

7 hours ago, diecaster said:

You need to look at this part of the Nelson Pass quote more closely:

 

Then there are things that don't show up in the usual measurements and we simply observe that the active circuit sounds better than the passive.

 

I file these under "How About That".

 

BHK says something similar in the video of his thoughts on active preamps. 

 

The bottom line here is that guys with a ton more experience than you think active preamps sound better than passive/none. I am not telling you that you have to like active preamps. But crapping them makes no sense. My 40 years of experience is audio sides with Pass and BHK. 

This would be my experience as well, but it is only if one uses a GREAT pre amp. I am sure there are some DACs with output stages as good as necessary, but they seem to be in the minority. Likely they are as complex/robust as a great pre amp. The armchair engineers seem to think pre amps aren't required, and technically that is of course true. When designers such as BHK or N Pass suggest otherwise despite not understanding the cause, one would think that at least others would keep an open mind. I guess there are experts everywhere.

[mav52]

8 hours ago, Fluffytime said:

 

Yeah, I've owned a Pass desingned amp, and I thought it sounded great. Massive kudos for Pass.

 

I just can't get on board with the deification of an audio engineer, no matter how good their products are.

I do enjoy my Pass

[pkane2001]

53 minutes ago, 4est said:

The armchair engineers seem to think pre amps aren't required, and technically that is of course true. When designers such as BHK or N Pass suggest otherwise despite not understanding the cause, one would think that at least others would keep an open mind. I guess there are experts everywhere.

 

You're putting words into NP mouth he didn't say, just to try to substantiate your point of view. He was talking about active vs. passive, and not about preamp vs no preamp. If preamps are technically not required, then why would you want them? Spend extra money? Or compensate for otherwise poorly designed equipment? What's the purpose of a preamp in a circuit that "technically doesn't require one"? 

[mav52]

7 hours ago, sandyk said:

 

 A good quality preamp usually has a far better output stage than most affordable DACs, often using a discrete output stage, and quite often also uses higher voltage .+ and - supply rails (> + and -20V) than most  DACs. They often use Class A topology as well.

Thats true.   Even in the same manufacture. When I upgraded from a AR LS17 to a LS27 is was a wow moment over the preamp section in the Mytek. 

[KingRex]

How does a DAC perform volume attenuation?   It has to have some sort of material inside it that varies something in order for the amp to know it needs to send more or less power to the speaker.  I'm asking out of pure ignorance.  My question on a passive vs internal in the dac volume control was to understand just this.  I get what an Alps pot, Autoformer, resistive ladder do.  I was once told how Pass Labs does it but don't fully get it.  I thought it had something to do with a semiconductor that had a ladder inside it. I really don't know.  If your going to say its all software, what is the software driving.

Thanks. 

[Panelhead]

10 hours ago, sandyk said:

 

 A good quality preamp usually has a far better output stage than most affordable DACs, often using a discrete output stage, and quite often also uses higher voltage .+ and - supply rails (> + and -20V) than most  DACs. They often use Class A topology as well.

  All small signal circuits operate in Class A. The power and heat  generated are very low. 

[sandyk]

3 hours ago, Panelhead said:

  All small signal circuits operate in Class A. The power and heat  generated are very low. 

 That is incorrect.

Most opamps need to have small circuit additions to force them to operate in Class A .

See Tangentsoft and DIYAudio threads for example.

 

https://www.google.com.au/search?source=hp&ei=VK6ZWqfeEoT88gWgiKb4Dw&q=biasing+an+opamp+into+class+A&oq=biasing+an+opamp+into+class+A&gs_l=psy-ab.13..0i22i30k1.2201.27259.0.33150.38.37.0.0.0.0.279.7320.0j22j15.37.0....0...1c.1.64.psy-ab..1.25.4953.0..0j35i39k1j0i131k1j0i131i46k1j46i131k1j0i10k1j0i22i10i30k1.0.tV3WKis9HAw

[GUTB]

Nelson Pass is an authority in amp design based on his public work in amp design, long experience and well-known expertise in the subject. Everyone knows preamps sound better, and Pass isn’t an exception. 

[Fitzcaraldo215]

5 hours ago, KingRex said:

How does a DAC perform volume attenuation?   It has to have some sort of material inside it that varies something in order for the amp to know it needs to send more or less power to the speaker.  I'm asking out of pure ignorance.  My question on a passive vs internal in the dac volume control was to understand just this.  I get what an Alps pot, Autoformer, resistive ladder do.  I was once told how Pass Labs does it but don't fully get it.  I thought it had something to do with a semiconductor that had a ladder inside it. I really don't know.  If your going to say its all software, what is the software driving.

Thanks. 

A digital volume control, as in many DACs, AVRs, HT prepros, etc., does not function by increasing/decreasing resistance, like the Alps pot, etc. It functions by merely shifting bits in a register without the necessity for moving parts or "wipers" or switched resistive ladders, etc. routing and thereby affecting the signal.  The digital control is, of course, done with the signal in the digital domain prior to any analog output stages.  

 

The digital volume control is noiseless and distortionless.  That is impossible to achieve with an analog domain volume control in an active or passive circuit.  Getting the analog control even close to the performance of the digital control is also expensive, requiring expensive parts.  The digital control is easily and inexpensive to implement and is already built into some DAC chips. 

[Fitzcaraldo215]

40 minutes ago, GUTB said:

Nelson Pass is an authority in amp design based on his public work in amp design, long experience and well-known expertise in the subject. Everyone knows preamps sound better, and Pass isn’t an exception. 

But, Pass also makes and sells analog preamps.  So, would his opinion not also be highly biased, as is, of course, your own? 

 

Everyone? I sold a very nice, very costly Levinson 380s line stage 10 years ago when I realized how much transparency it was taking away vs. direct play via a digital volume control.  That model had been John Atkinson's reference for a fair number of years at Stereophile. The 380s did sound great with analog sources, but did not fare well in direct comparison to digital straight to the amps with a digital volume control.

 

Actually, everyone knows that adding devices to the analog signal path cannot possibly make the signal better.  Unless heroically and expensively engineered to minimize its own inherent noise and distortion below audibility, it cannot come close to even a cheap digital volume control competently engineered, which really is not hard to do.