From what I remember - with TELPOD brand potentiometers, B taper means log (audio) and A taper is linear.
I have OD-02 on a breadbard now and log (A) is a way to go

ps. I've just measured Telpod 47k A - linear taper.

Any chance you could link schem of the Simple CabSim by Lart with bajaman mods please? Thanks Cheers Sono " update to the LART speaker simulator mentioned previously in this thread - to achieve a more realistic Celestion Blue top end response change: C2 = 39n C3 = 39n C4 = 10u electro C5 = 10n...

Thank you for the reply. So here's another one - on a drawing of a pcb there's a 3n3 cap - circled on a pic below. Looks like it's in series with 2k2. Also, power tubes - what kind of a switch is this? on/off/on (in the unit that you traced)? I'm puzzled a little bit because order of the switching o...

Saruman - I have some questions. Can you please check private messages?

Saruman - I have a question about diodes in feedback loop of the first opamp. Are these LEDs with such low forward voltage? 0.7V is rather unusual for a LED. I'm not sure if I've seen a LED with Vf lower than 1.7V (more or less).

Saruman - what modifications did you incorporate into a speaker sim?

What's after the 250p cap? Balanced output?

Some screenshots from the ltspice simulation. All the switches in the middle position. Gain pot - 250k, mic position 50k, presence and resonance @ 1/2. https://i.postimg.cc/5Xn6Kvqk/1.jpg https://i.postimg.cc/Z9n0GRwY/2.jpg https://i.postimg.cc/fScbc0RC/3.jpg https://i.postimg.cc/PvsxvMTN/4.jpg http...

The fix to the existing build is easy (crossing the legs of the pots) but it does not bother me that much. I've already corrected my version of the schematic and the pcb layout for the next build. Btw - smd version of the 4049UBM (UBE or whatever Uxx) is not that easy to find locally.

aionios wrote: ↑13 Nov 2021, 02:25 All right, y'all were patient - here's the full schematic.

Am I right that Blend and Filter potentiometers work the opposite way to the original? Full clean signal: Binary = max CW, Duality = max CCW. Filter, max treble: Binary = max CCW, Duality = max CW.

T.

If you still have this IC you can make a simple setup and check with the oscilloscope if there's crossover distortion present.
Build a simple gain stage, insert 1kHz sinewave and that's all

I figured the only way that could happen in this circuit is a bad op amp.
So I replaced the LF347 with a new one, and that fixed it.

I have couple dozens of cheap TL072 opamps (from Aliexpress). All with a similar issue.

On top of this page...

I have a question to CX-3 users/builders. I've finished one recently, with MN3007 instead of the MN3004. It works, but I'm not sure about one thing.. It's noticeable only on fast setting - modulation effect speeds up, slows down.. but there's this one brief moment like it was going to stop.. it's ha...

Thank you very much for your help george. I have to digest it all :) I was hoping for some non-invasive corrections, but it looks like it will be necessary to make a new PCB in the end. But first, some breadboard tests. Btw.. I'm almost sure that I've tested 2410 on a breadboard before making a PCB ...

Original circiut uses bipolar supply so GND to Vref is obvious for me. There's already 100u across power rail and 47u for the Vref.

I'll try to incorporate those modifications and report here.

Thanks!

george, thank you for all this explanation. I've just implemented the mods you've prosposed. Not 100% success but there's some progress. 1n across 10k does not change anything. With or without gyrator mods. Changed 510R to 1k, replaced 470k with 249k. Now, the oscillation apperars on power-on and fa...

I've put TL074 and TL072 there. I'm not sure if I have any smd quad other than TL074.

Some time ago I've build MARCus NGC2410 cabsim which is a NGC2400 with additional, third, gyrator notch fiter (around 560 Hz). It's just a copy of the first gyrator, but with 33n istead of 4n7. It's all 0805 smd, powered by 9V single supply, vref taken from a voltage divider (usual configuration). I...

Here you go

https://postimg.cc/1nHfrTcK