The Amp Garage

A few years ago I researched all of the lower cost scopes. I settled on a Keysight DSOX1102G as it seems to produce acceptable FFT plots while staying within my budget. It has a built in function generator, and also generates Bode frequency/phase plots. Perfect for quickly testing audio devices. Un...

I’ve read several of the threads on here, and understand the different procedures… Good - Balancing AC signal at PI plates/power tube grids, to compensate for PI tube imbalance Better - Balancing DCmV at power tube cathodes, to compensate for any power tube mismatch Best - Measuring speaker output f...

FYI, was able to rig my Mac for this using iSpectrum free software, the line out of my dummy load, and Avid audio interface… maybe not as accurate as the better scopes and RTAs out there, but gives me a great display of the harmonic spectrum with the ability to observe adjustments in real time, I.e....

I.e. I did almost everything you mention from what I recall and definitely could see some of the harmonics, but they'd sometimes be hard to tell signal from noise etc. Yes, that’s about where I’m at… I can see what I think is a 2nd harmonic, but can’t discern it as accurately as I’d like. Either wa...

Synchu wrote: ↑Mon Jan 24, 2022 11:51 am What Phil said.
I have Siglent 1102CNL. Spent quite a bit of time trying to make it work, but it didn't. Why they are stating it as a feature is beyond me

Glad it’s not just me! I think our scopes are basically the same, too.

Hey everyone, Trying to use my Siglent SDS1200CML 100mHz scope for some faux-spectrum analyzing and THD reading via FFT, but not getting very good results compared to what I see others doing on YouTube. I suppose I’ve hit the limitations of my scope, but any tips? This is primarily for P/P output ba...

Try this experiment - take a small metal plate, solder a long wire to it, and then isolate this plate well from a possible electrical contact. I use a wide masking tape. Connect the other end of the wire to the ground. Move the plate between the components and listen for the effect of this on the s...

Charlie Wilson wrote: ↑Fri Apr 10, 2020 11:20 pm If the clean / OD relay is wired correctly, the OD should be grounded out when in clean mode.
CW

Yes, everything is fine in clean mode. This minor problem only occurs in OD mode with pots at zero. I’ll be trying the ideas above tonight or tomorrow.

I don’t have a full schematic handy, and will snap a few pics later, but from input thru OD stages I’m going by the book... after that, I have a clean Master 1MA pot that only switches in when OD is bypassed (removing this had no effect on signal bleed). If I ground the signal at either OD pot input...

Hey guys, been doing my own take on the 124 circuit with a few tweaks, and while I’m incredibly happy with the tone both clean and overdriven, I get just a touch of signal passing thru with OD Level and Ratio controls set to zero... seems to be coming from as far back as the clean Volume, goes away ...

Matt J wrote: ↑Fri Apr 13, 2018 6:23 pm As far as I know, this is the highest serial # for an ODS I've seen that was still using a silver face chassis.

Is that a white faceplate on the front panel? Don't think I've seen one of those on an ODS before, but i'm far from an expert.

Thanks Phil! I’m gonna check it out on a new build. On a common cathode stage, it would theoretically give much more NFB than the 22m/.047uf network we see on some ODS builds (which I really love)... curious to hear it on the cathodyne split load.

Just curious, for anyone who’s built a Tweedle Dee, what’s your take on the 3.3M/2n2 LNFB versus just using a 470k grid stopper on the cathodyne PI input? Pros/cons? I’ve had no problems with just using the single resistor, but always looking for a better mousetrap.

Subjecttochange wrote: ↑Mon Apr 02, 2018 2:35 pm Sounds pretty good man. It seems you feel the same way about your bass playing as I do mine.

Ha, thanks! I'm doing a much more "pro" video with the player this was built for soon, hopefully this weekend. Will def link it here when complete.

Ignore the awful playing, but this should give you an idea... very proud of this one!


https://drive.google.com/open?id=1UB-sL ... IDQy8oyECK