Opinions on Bob Carver

[kt88pppamp]

Have any of you taken a look at some of Mr. Bob Carver's Designs? I think some his designs are somewhat unorthodox. I have a friend that has a solid state "signal chaser" unit. He hates the way it sounds and admits he let the salesman get the better of him the day he bought it. His tube designs are interesting but cost way too much money for what I believe they are.

I smell just sales and marketing. The term "high-end" is relative and almost exclusively defined by sales and marketing . What are all your thoughts? Any good or just expensive boat anchors?

[Geek]

Very overrated.

Look for the older commercial gear if you want the name.

Cheers!

[kt88pppamp]

Looking at the schematics, yes it is overrated in my opinion. Is it just the name that people want? If so, why was that guy successful? The people at my local audiophile shop said he set the precedent on the definition of "high-end." What source was he quoting?

Even if I had the disposable income to purchase such a system, I would not. My own designs rival or even (as recently demonstrated) best those commercial units.

I don't remember if I posted the tail of someone I know that owned an Audio Research Reference amplifier that caught fire. His teenage son left it on too long based on what I heard (I never asked the complete story yet). Given those things are on PC construction, they look weak, despite the high price tag. The reason for the smoke probably was poor ventilation.

I can feel the heat of PPP amps from two feet away. Cooping two quads of KT88 inside a closed space is not a good idea. I guess the thermal model was poor on the Reference 150.

[LinuxGuru]

Did someone tried Carver's DC restorer circuit for biasing output tubes?

[Geek]

Did someone tried Carver's DC restorer circuit for biasing output tubes?

I have seen a schematic for that. IMO John Broskie's supercedes it, as it's dynamic rather than static:
http://www.tubecad.com/2005/May/blog0045.htm

[kt88pppamp]

I designed my own servo bias system that uses a microprocessor. With my recent designs, I have found traditional bias circuitry with my recent work is very stable and additional complication is unnecessary.

Here is a brief overview of how it works:

- The processor uses ADCs to read voltage off a shunt in the cathode of each power tube.

- The microcontroller isolates the DC component of the signal with an averaging algorithm.

- A DAC feeds a high-voltage op-amp with a voltage reference. The op-amp amplifies the DAC value and feeds the control grid of the tube.

- The DAC value updates as fast as the averaging algorithm can run.

[LinuxGuru]

Auto BIAS adjustment is only one part of Carver's DC restorer circuit. Auto-bias servo is not that interesting - main is stable anyway, and I'm not an avid tube roller.
2nd (and most important) is to keep low idle current (KT120 @ 9W only) with low distortions.

Here are related threads:
http://www.audioasylum.com/cgi/t.mpl?f=tubediy&m=187251
http://www.audioasylum.com/cgi/t.mpl?f=tubediy&m=187358

After quite lengthy discussion, I seen no feedback from anyone. That's strange.

[kt88pppamp]

That DC restorer circuit is very simple yet Bobby and his salesmanship claims it works miracles. It does make the amp much more efficient. That is what I find most amazing about the circuit. Adding it to my KT88 PPP amps would be no big deal either. I may consider using it in Rev. 3 though.

The circuit is also nothing boast worthy as it was not originally used in Hi-Fi, thus Bob did not invent it, yet he claims it is as "his." I do believe he developed a unique version of the circuit for the amps, but was not the original innovator.

I do not consider the low distortion driver in my KT88/KT90 PPP amp as mine because Shannon used it in the EiClone. Someone alluded that it was originally a Mullard design, so credit goes to the folks that developed it at Mullard. I just happened to hit upon a very similar circuit unit to the original Mullard based upon research into stability, low distortion, and eerie simplicity.

[WA4SWJ]

I like the idea of a microprocessor controlled bias setup. I use 32-bit micros (overkill for this) for lots of things and have actually been thinking about this approach for a long time but haven't spent any time on it at all. I was thinking a DIP switch could be used to select the bias current in steps of 1 mA. But, this is off the subject here. I do like the idea a lot though. Perhaps another thread should be started on this subject.

Regards,