Attenuator vs. Dummy Load

[Pink Unicorn Horsey]

I have a 16-ohm THD Hot Plate, which I use with my Vox AC30 to hit its sweet spot without annoying my neighbors. I'm pretty clear on what an attenuator is and what purpose it serves.

Being interested in the sound Eddie Van Halen gets on their first album, I started reading through some articles online. All of these articles make reference to a "dummy load." I thought it was the same thing as a power attenuator but after reading all these articles I'm not so sure. It seems EVH put the dummy load between the preamp stage of a Marshall Plexi and an H&H power amp. My attenuator goes between the power amp and the speakers so here's my question: What is a dummy load and why would EVH want to put it between a preamp and a power amp?

- Keith

 

[the guy who invented fire]

Re: Attenuator vs. Dummy Load

Ed was using a dunny load so he could run thePlexi w/o a cab connected and not blow the tranny...a dunny load makes the amp think that there is still a speaker connected when there's not...Ed was using the Plexi with the H&H power amp, the H&H was feeding the speaker cab(s) so the plexi didn't have any cabs connected...the dummy loads kept the Plexi alive.

 

[Reckless Abandon]

Re: Attenuator vs. Dummy Load

I think in that case the dump took all of the voltage from the marshall and he used the power amp to play at his desired volume.

 

[Pink Unicorn Horsey]

Re: Attenuator vs. Dummy Load

Ed was using a dunny load so he could run thePlexi w/o a cab connected and not blow the tranny...a dunny load makes the amp think that there is still a speaker connected when there's not...Ed was using the Plexi with the H&H power amp, the H&H was feeding the speaker cab(s) so the plexi didn't have any cabs connected...the dummy loads kept the Plexi alive.

But I thought you only needed a load if you were pulling the signal from the power stage, not the preamp stage.

 

[the guy who invented fire]

Re: Attenuator vs. Dummy Load

But I thought you only needed a load if you were pulling the signal from the power stage, not the preamp stage.

if the amp is on, which is was you have to have a speaker load (or a dunny load) connected or the amp will NOT live long.

 

[Pink Unicorn Horsey]

Re: Attenuator vs. Dummy Load

Give it up, Corbic.

 

[Pink Unicorn Horsey]

Re: Attenuator vs. Dummy Load

if the amp is on, which is was you have to have a speaker load (or a dunny load) connected or the amp will NOT live long.

Perhaps it's the difference in wiring and options, but I can use the preamp stage of my Mesa Single Rec and pull the signal into an external power amp without having to load down the Mesa at all.

 

[Corbic]

Re: Attenuator vs. Dummy Load

I have a 16-ohm THD Hot Plate, which I use with my Vox AC30 to hit its sweet spot without annoying my neighbors. I'm pretty clear on what an attenuator is and what purpose it serves.

Being interested in the sound Eddie Van Halen gets on their first album, I started reading through some articles online. All of these articles make reference to a "dummy load." I thought it was the same thing as a power attenuator but after reading all these articles I'm not so sure. It seems EVH put the dummy load between the preamp stage of a Marshall Plexi and an H&H power amp. My attenuator goes between the power amp and the speakers so here's my question: What is a dummy load and why would EVH want to put it between a preamp and a power amp?

- Keith

What EVH did was use the dummy load after the Plexi itself. The Plexi was really the preamp for the whole system, in a sense, but was still the amp. He got his distortion from the power amp. He didn't put it between the preamp of the amp, he put it after the amp, but then put a seperate power amp after that, to control the volume. The typical setup was like this.
--------------------------------------------------------------------------
Marshall Super Lead Plexi (All knobs set to ten, and power cable into Variac set at 90 volts)
|
Dummy Load
|
Effects (Reverb, Flanger, Phaser, and Equalization. Basicly an effects loop)
|
H&H Power Amp (To control final volume)
|
Marshall Cabinets (One with Greenbacks, one with JBLs)
--------------------------------------------------------------------------
The Variac and Dummy Load are used to keep the volume of the Plexi low, but still get the gain and distortion of a cranked Plexi. It also takes strain off the amp from running at that high volume. The effects are set after the amp because using reverb, flanger, and phasing effects in front of a cranked Plexi doesn't sound good at all. So it is acting like an effects loop. The equalization was sometimes used, mainly as a mid-boost. He occasionally used an equalization pedal in front of the amp as a mid-boost as well. The final H&H power amp was used to get the actual volume of the amp. He could use low volumes for the studio, and high volumes for stage use, but still keep the gain of a cranked Plexi no matter what.

But remember, even if you get all that gear into place and use it exactly like Eddie did, his tone was in his fingers .

EDIT: Sorry, went a bit off topic into all of Eddie's gear and setup.

 

[Pink Unicorn Horsey]

Re: Attenuator vs. Dummy Load

That's exactly the explanation I was looking for, Corbic. Thanks!