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Building an Attenuator?

- Rated: 50 ↑
Jul 29, 2010 3:53 p.m. mark t:

I've been snooping around on the net for a bit, since i've got my kid for a week and need something to do to occupy my mind in the evenings. Originally, I was just going to build a volume box to go in the effects loop of my Hot Rod Deluxe, but now i'm reading about people mounting l-pads to the inside of their amp, between the output of the amp and the speaker.

Aside from the fact that they recommend you ignore the wattage ratings on these l-pads (A 100 W l-pad will supposedly only support a 40 watt amp max) and that the component has to match the ohmage of the speaker rating, what should i be worried about here? Or should i even be attempting this?

All i want, essentially, is to be able to get some good tone out of my hot rod at apartment volumes. And i don't really feel like spending a lot of money on a commercial attenuator if the same thing can be done myself.

Ideas?
- Rated: 7 ↑
Jul 29, 2010 4:00 p.m. SMacp:

You could try this.
- Rated: 163 ↑
Jul 29, 2010 7:03 p.m. Setzer:

Hey Mark, I picked up one of these dirt cheap awhile back and it works really well for what I wanted, basically what you described. It's old school and I use it with my 50watt amps and even some smaller wattages.

Altair - PW-5 Power Attenuator
- Rated: 88 ↑
Jul 29, 2010 8:15 p.m. BillyZoom:

It's very important to match impedances when you're using a device that allows you to drive your amp to maximum power at lower volumes. The amp is still working very hard, but most of the power is being turned into heat. Having the attenuator fail at full amp power will usually cause the amp to hemorrhage and convulse with dire consequences. A real L-pad will keep the impedance pretty constant, but a lot of them aren't really an L circuit. You're right about the wattage rating. They're designed for controlling the volume of background music in systems that are never driven into distortion. Also, you'll be replacing the speaker load with a resistive load, which will make the sound less interesting. A better sounding alternative is something like the Billy Zoom MultiWatt mod which varies the wattage of the amp by regulating the screen grid voltage of the output tubes. This makes the amp work less instead of more to get the cool distortion.
In either case, apartment volume is usually less than a watt. You'd amazed by how loud one watt is in your living room. Sometimes a smaller amp is a better solution.
BZ
- Rated: 50 ↑
Jul 30, 2010 7:47 a.m. mark t:

I was also thinking smaller amp, Billy. I like the idea of getting a Billy Zoom mod to my amp, but for the price of shipping to the west coast, I could probably buy a small tube amp.

Setzer, thanks for the link! I've never heard of those attenuators before. I think that in the interest of not frying my amp or burning down the world, i'll stay away from the l pad.
- Rated: 23 ↑
Jul 30, 2010 9:04 a.m. slapshot:

i am also looking for exactly the same thing .... for exactly the same amp :P (delux 4x10") i keep getting 404 or 403 errors whenever i try and get on a page at diyguitarist.com ....
- Rated: 45 ↑
Jul 30, 2010 7:43 p.m. Hermitt:

Have you seen the new eminence Flux Density speakers?

http://www.300guitars.com/2010/07/eminence-fdm-speakers-available-soon/
- Rated: 33 ↑
Jul 30, 2010 9:25 p.m. Blaydrnnnr:

I have a Blues Deville I've been doing alot of research on to try to mod a bit, any good findings would be greatly appreciated.
- Rated: 34 ↑
Jul 31, 2010 5:44 a.m. Geoff_Vane:

I think a Vox AC4TV or even the Vox AC4TV mini amp, may be a nice investment. Or the Zoom MultiWatt where you can select the power level the way it should be done.

Such amps can howl cranked all the way up, and they still won't be loud. Sometimes these kind of amps are used to mike in studios; no room filling screaming but still a proper cranked tone.

There is an attenuator made of a speaker motor without the sound producing cone. Far better than a plain resistive load, but even that device's manual says "you might see some smoke when it's new". I don't like the concept of attenuating tubes at the end stage at all, so building some DIY thing seems a bad plan to me.

http://www.tedweber.com/atten.htm

I fully agree with Mr. Zoom on this matter; the sound won't be great and the amp is used on the edge of what is wise, if attenuated at the output.
- Rated: 5 ↑
Jul 31, 2010 9:15 a.m. swift:

hi mark t : I've been thinking along the same lines but maybe eventually the best answer (as BZ suggests) is simply a smaller amp. This guy in the UK does custom amps based on a variety of cheap far-east imports

http://www.ratvalveamps.com/power-scaling

Has anyone got comments on the LondonPower system? Apologies if this topic has been run before...but I am close to buying a small amp so any info appreciated !
- Rated: 45 ↑
Jul 31, 2010 9:38 a.m. Hermitt:

Wouldn't it me cheaper to just build an extension cab with this new Emenince speaker that is designed just for this purpose?

http://www.youtube.com/watch?v=rpWqwCMZ1mo
- Rated: 28 ↑
Jul 31, 2010 11:38 a.m. Curto:

I'd give two thumbs up for Tom Weber's Mini Mass. I run one with my Blues Deluxe and it works wonderfully, all the tone even at very low volumes. Tom was very conservative with his ratings, no issues of heating or making smoke - enven though the web page makes mention of it. I think it was one of the best $100 I've ever spent...

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