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Discussion in 'Shock Brother's DIY Amps' started by Phrygian77, Apr 18, 2018.
Here we go again...
Are you thinking about externally accessible bias points and a bias-adjust pot, so you don't have to yank the chassis to adjust bias? That's a good thing to have IMO, and would be good to consider adding at your point in the design stage.
No, I'm building this for the guy that bought my last Princeton Reverb. He doesn't want any extra bells or whistles, other than the basic circuit mods I had done before, e.g., GZ34 rectifier, Deluxe Reverb output transformer, and increased phase inverter and preamp voltages.
Oh, it will have a 10k CTS fender style bias pot though.
The bigger OT really make a positive difference IMO. Good call.
I like it, and I like the 6.6k load. However, even with a 100mA PT, the GZ34, the DR OT, and the plates at 422VDC, the amp will probably only put out 15-16 watts RMS. I think the 1k resistor screen power node, vs a low DCR choke, keeps the amp from being able to reach the same output power of a DR.
Well, I was all set to start assembling the boards tonight, until I realized that I haven't checked and marked the foil side of my caps. It's too late now here to be making loud humming and buzzing noises. Oh well, this weekend.
Cool. Bigger PT makes a huge difference in headroom I discovered recently. Making the PR useable at more gigs. Unfortunately it then becomes a heavier amp!
That is a pristine cab!
Super nice looking cab! Beautiful work.
Question: On all of mine (Fender, Mojo, and several custom unknown) all have chassis support block/strips that are flush with the top of the speaker grill cloth, running almost to the back of the cab.
This cab either doesn't have ^ those or I just can't see them.
Maybe there's a reason for not-having those?
Ultimately I suppose the fully tightened chassis straps lift the chassis up off those pine slider-rails just a little so the only hassle would be during chassis mount/unmount. On a PR I could probably hold the chassis up with one hand, and thread-on all the strap nuts with the other, then proceed with tightening. On a Super or a significantly heavier chassis that might be more of a challenge. First-World problem, yes...
I always lay that style cabinet on its side to remove the strap screws and then upside down to slide the chassis out. Reverse to install. Don't fight gravity, and protect the front panel from flexing if it's a tight fit when the chassis is moved.
I didn't build the cabinet. That's a Peter Mather cabinet, mathercab.com. I've got a combo cab from him for a blackface Bassman and it's built the same way.
I always flip the cab upside on a bath towel, and slide the chassis in/out. Still upside down, I'll hang one side off the work bench to put a chassis strap on and put screws in, then flip it around to do the other side. Then I turn it right side up to adjust and torque it down.
Wow, that is awesome!