luvdunhill

Elecrow and PCBWay.

Nice!

Kerry, what is feeding these during the testing (bench supply?) and what is the load? Would you be able to do some measurements with some decent ripple in the input (say 500mV) and a decent load (1A?)

Kinda cute finding. The best matched JFETs from my pile, when stuck in the final circuit, result in -92dB THD and -84dB THD+N off my battery powered oscillator. That’s 0.0025% THD. The worst possible match (deliberately bad match) is -82.6dB or 0.0075%. Now, the offset trimmer value can be used to find the better performing circuit, as out of the 8 finished buffers, this trimmer value when DC offset is at zero, is directly proportional to the resulting THD value (this is because these JFETs aren’t really good complementary devices and so it all makes sense, just randomly noticed this when double checking some voltages)

The new Esoteric K-07x is worth considering. The “x” upgrade resulted in a completely different sounding “house” sound, no longer sterile and clinical. It’s possible to adapt the JDM version by replacing the transformer, if you are handy at the DIY.

More buffers - 10 transistors per board! [mention=431]Pars[/mention], interested in my two purple prototypes? Rails are 5v-50v and implements a kind of sliding bias (bias increases when load increases) centered around 10mA. They are DC coupled and low distortion. I will run all the new ones through the distortion jig in the morning and see how close they are.

Is the opto CTR important at all? I have some CNY17 in a few grades on hand. I use these to bias some output devices in power amp design. Ok, you have convinced me. I will get it queued up in the project list [emoji4]

Interesting, I added a simple trimmer here instead. Would these modifications work with the default batterys? I would think so. I am tempted to try these changes out [emoji4] What working voltage is needed for the 10uF cap and the one in the same position for the previous schematic (feedback/integrator cap)?

Will do in a bit - no components, but pretty cheap. Info here: http://www.diyaudio.com/forums/showthread.php?t=313775

Cool! The servo changes documented in the above post and that’s it?

I have a few boards left I can also send it your way, sure. The box is a cheap one and perfect for the job: https://rover.ebay.com/rover/0/0/0?mpre=https%3A%2F%2Fwww.ebay.com%2Fulk%2Fitm%2F262410258901

This is also the single still version, Maison Surrenne Galtaud, which was about double the cheaper stuff. Glad to supply if you are after something I have

Looks like you need to start claiming your home as partial business use. Maybe an ultra exclusive gym with one member?

2009 Lusi

First time wearing this since it came back from service.

I dunno, looks like the services of a certain retired circular hole cutter tech might be needed...

A mains fuse should be rated for the transformer, regardless of how much current the amplifier draws.

I believe this is absolutely possible, through varying distortion harmonic levels. I think for example, dominant third-order harmonics, could be a “voicing” of sorts.

In generally, nicer irons get you better recovery time (ahem). In general, use the largest tip you can, as things seem to go faster that way (squints). Preheating the board using a secondary source can assist in getting the deed done efficiently (slowly backs away).

You might calculate the difference in dB - usually a good ear can hear say 0.5dB difference - might be a good sanity check.

Does that make Steve, Otis?

... or properly sized ground spokes instead of solid ground plane connections. Just taking a board and ordering it with moar copper isn’t always the best idea.

So, general features I am after are: Momentary switch operation Remote trigger input Support for more than one temperature sensor (not thermal breakers) Antiparallel bi-color LED indication Support for AC-DC switcher and AC transformer footprints High current relay control (mechanical and SSR, though I am done with SSRs) Probably three PCBs - transformer, control and relay. Other requests? Maybe IR control?

Done some work on this. I've come to the conclusion to do the logic I'd like, I really need a microcontroller. So, going to start from scratch with that assumption. Sigh.