Carver Pro ZR1600

Regarding mods...After studying the schematics, and reading about Mod activity, I "popped the cover" (a simple matter of sixteen screws) and looked inside. From what I saw I don't think much is practical with a few exceptions.

The fan replacement (with a quieter model) is easy.

Bypassing all the preliminary signal processing stuff with a wire to the amp itself is practical. Connection can be made without great difficulty at a coupling capacitor location.

Input and output terminal hardware can be changed, although what's there looks OK to me.

The inputs are on a small separable assembly which occupies a shielded box about 4X3X6 inches. It connects to the mother board with a plug-in cable. There is lots of room for a completely new input/driver/processor circuit: for example a Marchand electronics crossover module would fit with room to spare. Carver plans to sell various modules to replace the standard input circuit, but they have not yet told us what will be offered.

Now the bad news. The components (including IC OP Amps) are all surface mount which I find almost impossible to remove/install. There are many. The chances of swapping out all the OP Amps without destroying some part of the circuit board is near zero IMHO. With perhaps a few exceptions, the existing circuits cannot be upgraded with better components. You would have to go completely around them with a wire or with completely new circuitry.

If audiophiles think that the ZR1600 would be better without various ProSound features, and with some better capacitors here and there, the obvious course of action is to get Carver to build an "Audiophile" version. Carver would do well to hire some of the better known Mod people as consultants to do the design. I suspect that the audiophile version would cost no more to build, as quite a lot of circuitry would be eliminated.

I have it on good advice that Carver Pro has already tapped Stan Warren as a consultant on the matter of a stripped down audiophile version, doing away with all the ancillary circuitry, such as the junk op amps and clip limiters up front, and some more useable audio jewellery on the back, with a view to producing a great amp that does more, for less, and come in 'under the radar.' This movement is currently under way. Stay tuned.

Dmason...I hear the term "junk OP Amp" used a lot lately. What does this mean?

With the exception of noise, the open loop electrical characteristics of an OP Amp have almost no effect on how it performs in a circuit, especially for a unity gain buffer application. All that is necessary is high open loop gain and slew rate sufficient to handle the highest frequency of interest. These minimal requirements on the active amplification devices is the reason why the OP Amps circuit is so widely used in all kinds of electronic equipment.

El: Op amps have the potential for high quality sound, but most Op amps are under-designed mass produced pieces of junk. They work great for many applications, but many of them just aren't suitable for use with "hi-fi". On top of that, when put into a circuit that is an under-designed piece of junk, you end up with one BIG under-designed piece of junk.

If you would like further clarification as to why many Op-amps are "junky", try reading a very informative article written by Ben Duncan as published in Stereophile a few years back. This amassess the results obtained after testing over a dozen different Op-amps from various manufacturers. Some of the same Op-amps from different manufacturers performed VERY differently. We are talking about S/N ratios that varied by as much as 40 - 60 dB's here. Needless to say, a few dB's here and there might be understandable, but not variances as mentioned above.

As a side note, this article also mentions thermal distortions, which most IC's are not very good with. Sean
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sean...Yes, noise is a significant characteristic of an Op amp. However, the OP Amp circuit topography is such that an IC which is "junky" in other ways, like distortion (thermal or otherewise) gain tolerance, slew rate tolerance (as long as it is above some value) etc, will work just as well as an OP Amp that is perfect in these regards. Op amps can only be evaluated in context of the performance of the overall circuit in which they are used. They should never be thought of as a linear amp.