quick drawing for identify original capacitors :



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My last thoughts to optimize the Tube-I-zator goes to the B+ High Voltage lines.
To get the maximum flexibility, i have made splitting points in the lines.
The splitting of the anode psu lines brings upgrades possibilities.

You could use e.g. a tube rectifier with C-R-C filter instead of the onboard andoe psu or
switch to a regulated shunt psu, witch in my mind brings the greater sound quality upgrade.

With the experiences from Salas low voltage shunt on my DAC project in mind,
i have made an upgrade module for the Tube-I-zator based on his HV shunt circuit design.

Here it is

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To try out Class D without working too much, I picked two ready-made Class D amplifier modules: one is the $45 2*100 Watt Class-D Audio Amplifier Board from Sure Electronics with the optional $10 volume control board, the other is the $199 IRAUDAMP7S from International Rectifier.

The Sure Electronics module is based on Tripath's TK2050 chipset. Powered from a 150W 24V SMPS from Mean Well, it predictably puts out about 22W RMS to a 8 ohm load. (The declared 2*100W requires a 30V supply and a 4 ohm load.) The sound and the measurements are decidedly mediocre, although at the $45 price, the module still may be a good value. Also, the volume control board feels odd, as the knob only adjusts volume after a push; another push disconnects it again.

The IRF module requires dual rail supply, for which I chose an SMPS400A180 by hypex. With +/-40V rails, the amplifier delivers 100W RMS into a 8 ohm load. The measurements are good, and the sound is very interesting for...

im trying to build a leslie from mix and match parts so far ive got the speakers amps and crossover kits. im having trouble with what im going to do with the motors. does any one have any information on how to build alternative leslie speakers. i'm a beginner to build these types of things so the simpler the better.

Plenty of helpful advice in response to my question on emitter resistors, here.

And so finally I finish my prototype Sapphire amplifier, pictured below. The case is from Chinese audio outfit hlly, and very good. I bought it on eBay.

The rest of the components are described on my web page.

Since I was effectively blogging my progress with the project as a forum thread anyway, perhaps it would be better to make it a blog rather than a post. I'm open to the idea, but does anyone ever read these blogs?

LME 49811 schematic is the one used for the tests with only the 30pf compensation in the circuit.

I don't find it hard to believe that very low levels of certain kinds of distortion are detectable when at the same time virtually un-measurable differences between passive elements like cables and capacitors are widely believed to be audible.

THD-20 does not tell the whole story on amplifier behavior, but it has also been given a bad rap because single-number usage of THD-20 can obscure the real story. If you have THD-20 with a full-spectral analysis out to the 7th or 9th harmonic, it tells a lot more, but most THD analyzers start cutting off at 80 kHz. One should always take note of the waveshape of the THD-20 distortion residual as well. If it is rather sinusoidal, that is often not too bad. If it is spikey, that is potentially very bad.

CCIF 19+20KHz with full spectral analysis is much better because the IM products lie in-band.

At the same time, moderate levels of benign THD, like mostly 2nd and 3rd, may not bother anyone very much. This...