Pro Audio Design Forum

Moving on to the thought of a variac controlled PSU for tuning filament voltage, followed by B+ control. Seems the most elegant, so long as filaments within the PSU are acceptable. I have 2 supplies that do 300 mA B+ or more, and both do 10A of 6.3V. Found some ADC Christmas Tree terminals in the pi...

I'm staring at various PSU's I have, and a rack full of various tube preamp systems, and it's getting out of control. Starting think about solutions. I have multiple tube regulated B+ supplies that seem perfect, several adjustable in the 200-325VDC @ 325mA range, but no need to power up everything e...

A 5534 and a 1646 would be another simple output combo here too, either driving an output transformer or not.

A rundown on some tests and personal discoveries about LC filters, and viewed in the context of a Pultec MEQ filter clone . In my build, we see 11.2 dB cuts and 9 dB boosts. Some of the plots here were done with 5Hz resolution, so the bottom is bumpy and imperfect. I added some additional low bands ...

Total available space was about 1" x 1" x 1.5" at most. There was no transformer that would fit the space and mounting, and do the job acceptably well, thus this solution. I had a Pultec EQP-1A clone visit the studio, and was able to compare the Q of the high band LC filter with the M...

I had need to put an active buffer/driver in front of a Pultec style mid-EQ filter, and I had these parts, so I put a 1246 in front of this 1646 configuration. It's working very well, and not breaking a sweat at any filter setting. I had two of this filter temporarily running with no buffer, single ...

Still not truly solved, but working in the field.

mediatechnology wrote: I think that was the motivation for bruno2000 (live) to use pots in his preamp build.

Oh yeah, no jumps allowed if they ever go in the remote truck.

I haven't thought about it but how does a bridged T increase the accuracy? Resistor sets working in parallel, so you are trimming a preset standard ratio. No serial errors, or at least far less. I submit the existence of 1 and 0.1 dB step controls on the standard decade attenuator as evidence. That...

Nice. What do you have there, a factory? Yer killin' me.