Disadvantages of OP amps in output stage of CD?


I was informed that "op amps" in the output stage of a CD player can produce thin, less full, and bright sound quality in the upper midrange,(which I have heard on my CD player) In addition, I was advised that these digital by-products can be reduced by taking the digital output signal from the player and feeding it into a good DAC with a discreet class "A" output stage

The CD player I have is a modded Cambridge 550C. I don't understand "HOW" this addition will or can improve the sound quality. Will it prodice a fuller and smooother midrange?? I also don't want to add another box to the system or spend $500-600 plus for a good DAC. Any advice and comments will be greatly appreciated. Thanks
sunnyjim

Showing 1 response by almarg

First, an op amp (short for "operational amplifier") is an analog device, and cannot produce digital by-products.

Second, I would not by any means NECESSARILY attribute the objectionable sonic characteristics you are describing to the op amp stage of the player. There is a whole lot of other stuff in the player that can also cause or contribute to that, including the player's DAC (digital to analog converter) circuitry. And the sonics provided by a specific electrical design approach, besides depending on the circuit design and on the specific parts that are used, can even differ considerably depending on the mechanical layout and design.

More often than not, though, it can be expected that the choice of an op amp-based analog stage, as opposed to a stage based on discrete transistors (not "discreet," which means something else) will have been made with cost as a key consideration. High-end designs tend not to use op amps, at least in the signal path.

Purchasing a standalone DAC means that you would no longer be using both the DAC function and the output stage of your player. Can that result in a "fuller and smoother midrange"? Certainly. Will it? Obviously, it depends on the particular DAC, as well as on what part of the existing player is the predominant contributor to the problem.

Changing to a different CD player could also, of course, accomplish the same thing, depending on the particular model.

Also, a two-box approach can have its own set of tradeoffs. If not well implemented, noise pickup and impedance mismatches involving the interconnect cable and the interface circuits in the two components, as well as groundloop effects between the two components, can result in random fluctuations in the timing of the conversion of each digital sample to an analog voltage in the DAC, which is referred to as jitter, and which can have very significant sonic consequences.

Hopefully others having particular knowledge of products in that price range will chime in with specific suggestions, covering both one-box and two-box approaches.

Regards,
-- Al