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Yup tubes are the same - you'll get differences, so you get used to "rough ball park" figures, build it and then fine tune. The fine tuning you know will change between tubes so in the end that has to be redone on the tube changes if you get into that level of 'detail'. Then you remind people...

The AC128s arrived, I deliberately asked for a cooler pair and a hotter pair.

The other option is to add bypass caps to the power pins so any current loop between the opamp power and ground pins is kept as small as possible through the local bypass cap, adding an inductor on that power with a cap at the other side means a CLC filter. The LDO (low drop out) means a little...

Milled case should be able to take punishment.

Do you know what frequency is causing the feedback? How much current? Problem with RC filters is that you loose voltage headroom. Inductors can work well, as too can LDOs like the LT3042.

Virtually all the compressors pass through the signal and then have a side process that feeds back an attenuation. This means the large Vpp is already past the attenuation stage and out the door. The issue is with feed forward attenuation, ie where the signal is attenuated after it's sensed...

So here's an annotated image, this should make more sense now given the above information. Note I have resistors in series to make up values that are shown in the schematics. The two parallel caps are the 0.30uF decoupling caps in the schematics. The input is the small wire I need to use a...

Post 2/3 - the schematics. Signal Path Stages: 1. Variable Mu 2. Constant Gain 3. Output Driver The Control for the Variable Mu: Power filter and regulator: The little TVtrim pot allows the fine tuning, if your primary voltages differ from mine, you will need to adjust this too. The output...

COMPETITION ENTRY Post 1/3 - Overview. Entry: A prototype 176-inspired class A tube compressor. This is complex, so before we get to the build images, I will walk you through the architecture. After that, the schematics and build images will make sense. The system is split to three main...

I agree, I don't think the transistor has really progressed much in terms of the curve and as you've said the substrates and junctions have improved dropping the noise. The speed of transistors above a certain point result in little return in the audio range - the BC549 is 300Mhz, its...

Love the graphic too.

The poor pots and good luck getting 1/2” plugs in :ROFLMAO: Use the pots that screw to the front panel, don’t use the thin plastic pcb mounted ones - dropped on it and the board is broken or traces ripped. Don’t have open controls like sliders on foot pedals where dirt can drop in. Don’t have...

Potting would make the pedal a throw away device. Think about the poor tech needing to source and replace parts.

I think main heard difference is the sharpness of the edges.

Wires between offboard components and pcbs prevents broken solder joints on shocks. Also avoid low temp bismuth solder that creates brittle joints.

3 videos uploading * sine wave showing attenuation on scope * guitar into scope showing attenuation * guitar into amp where you can hear the difference vs hard hitting the front end of the JCM hight gain. These are uploading and processing.. Signal generator+Scope You can see the purple...

So from a model perspective I think this is the best I can tune to: 1. This is the starting point - this is the compression curve, I'm looking to keep a curve but after the point and shape. The curve here is measured in Vpp so it's already peak-to-peak for both input and output. This is ok...

I have four Mullard metal can AC128s coming. I almost added two AC125 NKT275s (non dotted) to the order.. but let's start simple. I've asked for two pairs - one lower gain and one higher gain, both pairs about 20-40 apart. It would then give more OD and a harder fuzz. For silicon I'm tempted to...

If you want to play with that further - a Schmitt trigger would clean up the switch (well the signal itself rather than the switch but that too), sharpening the corners and a tuned snubber would help absorb some of the noise. You may also find that noise washing back up the power line too, so...