Curious_George

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I understand. You are excited as you should be. I think you are going to like that amp.

But that is not the one Henry just built. Which one are you getting?

I had never heard of it before you brought it to my attention. I’m fascinated by the concept. Good stuff.

I did. I read the one about Mesa Boogie, but not the email one yet.

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Even though I say I can't hear a difference between M6 and Z11 (which is Hi-B or high permeability core), I keep going back to my James OPT's that are Hi-B. They do sound great. Tango and Hashimoto use Hi-B as well. Z11 will allow you to use a smaller core with eveything else being equal. Apparantly, Hi-B is used by power companies extensively to reduce core losses in industry and utility pole transformers. Makes sense.

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I think you would like (sonically) my version (mono amps) of the Williamson's that I made.

Yep. Although I have been on the SE train, I go back and forth between SE, Push-Pull (with feedback) and solid state. Then I'll start messing with speakers, etc and the cycle just goes round & round.

I have suspected this for a long time, especially with certain Chinese type tubes. For example, New Sensor Corporation who makes tubes (New Sensor uses a Russian factory) under the following brands: EH (Electro-Harmonix), Tung-Sol, Sovtek, Mullard, Gold Lion, etc cross markets all these tubes such as 5881, 6L6GB/GC. I suspect they are the same tube with different price points. same comment for EL34's. I have some EH300B's and they are nice, but the exact same tube sold under Gold Lion are twice the price. If you do your homework, you can get great tubes, but at a lower cost. Just have to poke around and ask questions.

I typically do not use an input cap on amplifiers, tube or SS. When I redesigned my Phase Linear driver board for the 400/700, I did populate the PCB with the option to use back-to-back electrolytics to essentially emulate a non-polar input cap. I can't say I have owned or looked at all the equipment out there, but in my experience, almost all sources and preamps usually have no DC-offset, unless during the power up sequence, which is why you turn your source on first, then your preamp, then your amp. By contrast, you do the opposite when you power down your equipment. Granted a film cap is not that expensive to use, but you know how people feel about caps in the signal chain. I don't have a cap phobia, I just only use parts when they are needed.

I did not measure the bias this time, but I will make a spreadsheet of the various tubes I have (EL34/6L6) for comparison.

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RF & audio transformer winding; black art, luck and empirical experience, no doubt.

Just because the OPT's look potted, don't mean they are potted. On four of the five Chinese amps I have bought, only one had "true" potted OPT's. The other ones only had cosmetic covers. The Chinese military hardware is the same way...

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I believe I scanned the whole book at one point, but the scan was kinda crooked and I wanted to redo it. I'll see what I have and possibly upload the entire book.

I have his book "Total Harmonc Distortion". It is an audio classic!

A lot of modern amp gear does not have an input cap, because it is understood most modern preamp gear has an output capacitor. Eliminating the input cap, Decware can claim fewer components in the signal path, more ingenious marketing.