TL;DR: How can I tweak this 5532 circuit for more reverb in the mix on my one-owner Mesa Boogie Rocket 44?
To begin, I bought this Boogie off the showroom floor around the turn of the century. It was great for a while, then had some issues and got sidelined for decade or more. A couple years ago I finally got around to diagnosing the issues. One of the main filter caps mechanically failed internally. Not knowing why and not willing to risk it, I shot-gunned the electrolytics. When I tossed to back together to test, it had a gnarly hum. It got set aside as other projects took priority until just the other day. As it turns out, I had forgotten to properly tighten the input jack, causing all sorts of problems. Now that the amp is back to where it was originally, I decided to address some of the concerns I had with it. The blatant abuse of the EL84s in the DC3, Rocket 44, and F30 amps was dealt with by paralleling one resistor with another early in the bias circuit. I'm still considering adding a zener to the CT, but that'll require more bias circuit tweaks, so that's a back burner issue. The depth of the reverb is the other issue to be addressed.
Having read another thread here about Platefire's Rocket 440, I tried increasing the feedback resistor for the reverb return. I had a helluva time finding the correct resistor, just as they had. As it turns out, the resistor in mine was a 121K, not the 220k on the schematic. It was found by meticulously probing around the circuit until I was confident I had the parts ID'd correctly. At first, I put a 1M in series, per PRR's suggestion in the other thread. This let out an ungodly howl at the slightest crack of the reverb knob. "Too far!" I thought. I decided to put in a 220k, as per the schematic. It works, sorta. There's a lot more reverb, but also a LOT more hiss, and it starts to feedback if set above halfway. To dial that in, I'll parallel some other resistors to find the sweet spot, or the point at which the extra noise is tolerable.
Here's where the questions are: My understanding of SS circuits isn't as strong as I'd like, so I'd like some input on what other parts of the circuit can I look at to get more reverb without increasing the noise. Would lowering the 56K resistor after the reverb pot give me any leverage? It seems like it's limiting the total output of the the reverb by 1/3 or so, but it could also be serving some other function I don't wholly understand. Would changing the reverb pot to 250K or 500K work? Maybe I'm looking at the whole thing wrong and I should be looking at driving the tank harder and keeping the return as clean as possible for the best possible s/n?
Topic: Help with tweaking SS spring reverb - Mesa Boogie Rocket 44 (Read 2101 times)