resister source

[dazzlindino]

Where can I find 200w - 100 ohm / 470 ohm aluminum extruded resisters?
Thanks.

[Enzo]

Mouser has the 100 ohms in stock, and lists the 470 ohm but is out of stock currently.

I would also search Allied, Digikey, Newark and so on.

Those are odd values for resistors of that power level. WHat is the application? The Mouser examples cost about $45 each.

The smaller 50 watt aluminum resistors are only $3-4 each. Get four 100 ohm 50 watt ones and wire them in series parallel for the 100 ohm 200w result, but the cost would only be $12-16.

[dazzlindino]

Thanks for the reply, just trying to burn up a few more vintage marshalls........

[Joey Voltage]

Thanks for the reply, just trying to burn up a few more vintage marshalls........

Cerrem mod?

[dazzlindino]

Yezzer.....any stories?

[Gtr_tech]

FOr Enzo's edification....the "cerrem" mod involves placing a high wattage resistor across the plates in a P-P pair to cancel some output signal...sort of an internal attenuator. Not the greatest idea I ever heard of, but it does work...for as long as the tubes can hack it. Some flyback diodes in there would be a wise idea to give the spikes somewhere to go.

[Enzo]

Thanks, didn't know that one. I really don't travel deep into the mod circles.

My 250 watt Dales are 6.5" long over the studs and 3" wide over the mounting tabs. If a 200 watt was remotely this large, where on earth would you put it in an amp chassis?

[Gtr_tech]

Guys that dare to do this are using an outboard box/heatsink with modified tube socket adapters that allow a lead to come out for the plate connection. Arrays of series/parallel Dale aluminum ch. mt resistors. Fuck all that....if I wanted to waste a bunch of output tubes I'd go up on the roof and toss 'em out on the street one at a time.

There's a huge thread over on Plexi Palace about a guy who took a bassman head and ran the ext spkr out (leaving the main spkr jack unused so the output was grounded, but theres always that little bit that gets through to the ext jack) to another amp input. It actually sounds real close to the early VAn Halen guitar sound....closer than this "resistor mod" does.

Not that that's a new idea...its prolly what Ed did in the old days for the most part. But The first one I know of to do that was Randy Bachman from THe Guess Who. He did it with a Champ into another amp, but didn't know to use a dummy load on the output of the Champ....and roasted it frequently. Then Gar Gillies (Garnet amps) told him that was a stupid way to do it and built him the "herzog"....basically a champ circuit with an internal dummy load and a safe line out.

[Chuck H]

There's a huge thread over on Plexi Palace about a guy who took a bassman head and ran the ext spkr out (leaving the main spkr jack unused so the output was grounded, but theres always that little bit that gets through to the ext jack) to another amp input.

That guy was here for a moment, But the thread didn't get long. I think it was just myself and Enzo that responded.

As far as this "Cerrem" mod thing...Why would you just strap a resistor of that size across the primary. I don't see a reason you couldn't also include some series resistors to make the thing impedance correct and that should keep from ruining OTs and tubes. You might want to drop the screen voltage a tad. Or you could run a higher than rated impedance load off the secondary too without series resistors. that would also help. The flyback diodes are a good idea. An attenuator built on the OT primary is something I have considered, but never really dug into.

Chuck