|
Digital Drive Upsamplers, DACs, jitter, shakes and analogue withdrawals, this is it. |
|
|
|
Digital Drive Upsamplers, DACs, jitter, shakes and analogue withdrawals, this is it. |
|
In Reply to: Thanks Peter posted by John C. - Aussie on November 30, 2004 at 14:36:45:
Dear John,The problem is not between the transport and the DAC, there are no tubes there, the problem is between the output of the DAC and the input of the pre-amplifier.
The DAC One.1x uses a small sub miniature double triode called 6111WA, it is run as an anode follower without feedback, this results in a high output impedance of around 3kOhm.
I know that Plinius say their integrated has an input impedance of 47kOhm, but I think the truth is that it is much lower than that and this is the reason you get the result you describe.
Valves are high impedance voltage amplifiers, transistors are the exact opposite (current amplifiers) and in addition they need corrective measures to provide a linear bandwidth at audio frequencies.
When I speak about opposing philosophies, that is what I am talking about.
Because a core parameter of a valve's behaviour is linearity at audio frequencies, this allows us to design using valves in simple open loop circuitry.
We use transformers to step up or step down impedances and current voltage relationships. We believe that "less is more", so to get the closest facsimile to what is imprinted in the software passing the signal through fewer parts is of primary importance. We choose our circuit solutions and component choices very carefully, based on a well considered evaluation system (Comparison by Contrast), we belong to a minority in this regard.
Plinius, Meridian, Krell and all other semiconductor amplifiers use highly compensated (read here feedback) complex low impedance circuitry, they rely heavily on measurements to ensure "quality".
Just open up the Meridian DAC and compare to the component count in the DAC One.1x Signature and the difference should be obvious.
The question you should ask yourself is, whether the complexity and component count of the semiconductor "school" of design is a better solution than presenting the signal with fewer parts and gain stages.
My contention is that a sure sign of mediocrity is the love for needless complications because if it is complicated it looks "sophisticated", many will disagree with me, but I think the philosophical point is clear.
Like I said in my earlier post, unless you make some major changes to your system, you will never hear what the DAC One.1x Signature is capable of, dozens of customers are presented with conundrum every week, so you are not alone.
Having said that, the new DAC1.1x/II has a much lower output impedance (about 1K) and should work better in your present environment, it also has no analogue filters, which in turn may upset the stability in your Plinius amplifiers as the out of band noise mixes into the feedback loops.
We live in different worlds and mixing products from each more often than not give unpredictable results.
Sincerely,
Peter
This post is made possible by the generous support of people like you and our sponsors:
Follow Ups
- Re: Thanks Peter - Peter Qvortrup 01:49:50 12/02/04 (1)
- I finally get the picture thanks (nt) - John C. - Aussie 15:37:35 12/02/04 (0)
Top of Page ]
[ Contact Us ]
[ Support/Wish List ]
[ Copyright © 2025, Audio Asylum, all rights reserved ]
