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Bradley, Bellomo and, Nachbauer Hi-Gain Preamp V2

I listened to all of the amps online that I could. Cris Bradley's "Bradley Hi-Gain 50 watt" sounded the best so I decided that I would rip off his preamp--which he designed after studying Mesa and Orange designs and very smartly modifying the marshall jcm circuit. I suggest you go to that link now and listen to the amazing sound clips.

Simply amazing.

My main challenge was to find a cheap way to power JUST a preamp. Luckily Fred Nachbauer perfected the art of DIRT CHEAP high quality tube preamp power supply design. Without Fred I would have had to listen to the snobs who were telling me to breakdown and buy a Hammond tranny. That just never felt right. This was supposed to be the poor man's alternative to the Matchless hotbox and the Marshall jmp, and countless other bandit products created under a basic false premise that a preamp should cost as much as a corresponding full amp.

Why chould you pay $1000 dollars for a jcm 800 preamp when a full jcm head is selling for the same price? Okay, so my logic is tortured, but still. Why should 1920's technology with a total parts cost of 50 bucks cost more than about $50?

Brass Tacks
Power supply Schematic
The 'Bradley Hi-Gain' Preamp


The crazy knob layout is actually the best point-to-point layout possible for the tone stack section of the amp. Infact, The whole preamp follows ptp philosophy religiously.

There is exactly one 5-lead terminal strip I grudgingly incorporated in the preamp to facilitate star grounding layout. Everything else is component to component.

The power supply needed more support so I incorporated two terminal strips there. I used a cube chassis I bought from Fry's and drilled holes with a dremmel. There is a transformer inside and outside of the chassis.

Originally I wanted the power supply in another chassis but that meant a long cord carrying 330 volts in addition to the standars wall socket cable. It was all too unwieldy and I was sick of paving useless new ground.

After almost a year woking and learning I was tired. The V2 was finished in early October, 2005 when I recieved the input jack insulators from mouser and completed the star grounding scheme eliminating all residual hum.


If you want to see the madness of the first year leading up to the original BBN (Bradley, Bellomo and, Nachbauer) click here to see the original BBN V1 web page.