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Switchable attenuator project...

11/19/2005 6:15 AM
Keith	Switchable attenuator project... I recently got a 5e3 clone and am loving that cranked power tube overdrive. Using it with an l-pad attenuator I get good overdrive at reasonable levels. Cleans are a problem with the attenuator though so here's an idea I'm thinking of trying. I have an a/b box I'm planning to use to switch between the two channels of the amp. One channel with the amp volume control set lower to get an unattenuated clean sound. The other channel's volume control will be cranked to get that power tube distortion while having the l-pad engaged to keep the volumes the same for both channels. I plan on using the 9v power for the LED indication on the a/b footswitch to energize a couple of 9v relays to switch the l-pad in for the distorted tones and out for the cleans. By doing it this way I only have to step on the a/b switch to change channels and switch the l-pad in and out at the same time. I have two questions. I wonder if it will pop or click when switching and if the amp could be damaged during the relay transit time. Max switching time for the relays I plan to use is 10ms. Would 10ms without a load damage the amp? I guess I could wire up a power resistor to plug into the extension speaker jack which would supply a load during the relay transit time and also reduce the amount of attenuation necessary. So what do you think? Keith

11/19/2005 6:15 AM

Keith

Switchable attenuator project...

I recently got a 5e3 clone and am loving that cranked power tube overdrive. Using it with an l-pad attenuator I get good overdrive at reasonable levels. Cleans are a problem with the attenuator though so here's an idea I'm thinking of trying.

I have an a/b box I'm planning to use to switch between the two channels of the amp. One channel with the amp volume control set lower to get an unattenuated clean sound. The other channel's volume control will be cranked to get that power tube distortion while having the l-pad engaged to keep the volumes the same for both channels.
I plan on using the 9v power for the LED indication on the a/b footswitch to energize a couple of 9v relays to switch the l-pad in for the distorted tones and out for the cleans. By doing it this way I only have to step on the a/b switch to change channels and switch the l-pad in and out at the same time.

I have two questions. I wonder if it will pop or click when switching and if the amp could be damaged during the relay transit time. Max switching time for the relays I plan to use is 10ms. Would 10ms without a load damage the amp? I guess I could wire up a power resistor to plug into the extension speaker jack which would supply a load during the relay transit time and also reduce the amount of attenuation necessary.

So what do you think?

Keith

Replies:

Keith Update on the project: It works! I'... -- 11/28/2005 5:30 PM