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/diy/ - Do It Yourself

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22465 No.22465 [Reply] [Original]

I want to build an anttenuator so i can crank my valve guitar amp without destroying my eardrums.

I have already made one using a 100w L-pad, but it only worked for a few minutes until it burnt out.

I have heard that the 'tube cube' attenuator that sells for over $100 on ebay is nothing more than an impedance matching volume control.

would it be a good idea for me to just buy a 100w IMVC and wiring it to a input and output?

>> No.22489
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22489

Here is the one that i built.

I used the case from an old PSU and hooked the existing fan and switch up to a 9v battery.

>> No.22496
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22496

the blown L-pad

>> No.22686

>>22465
What are you trying to do? Get distortion? Overdrive at the preamp level instead.

>> No.23186

Simply rig up a resistive PA. They work good, and can be cheap as fuck if you use chink resistors (check Royal Ohm, they are 10W and cheap as sin (you can parallel several to achieve the wanter power absobtion doing the right calculation on the Rtot)) .
If you leave like 2W going thru the amp (is well audible) you can wire a further volume control with wirewound potentiometer wired as voltage divider (like a 50ohm 2W wirewound).

I use a T-pad type
http://en.wikipedia.org/wiki/T_pad

>> No.23243

>>22686
>Overdrive at the preamp level instead.
You will have only preamp distortion. Power stage distorts too, and some tube amps have the most of their shine in the power section. Therefore, Power Attenuators.
>WARNING: PA will wear your tubes as if you were playing full crank without it. Might sonud obvious, but to many it's not

>> No.23286

Could you not just rig up a resistor network? say you had an 8ohm driver (speaker), stick it in series with another 8ohm resistor and then stick the pair in parallel with a 16 ohm resistor, the amp would still see an 8 ohm load but only 1/4 of the power would be dissipated by the driver.

>> No.23324

>>23286
L Pad and T Pad configurations are resistive.
The way you say is basically a L Pad.