Attenuator Help!

[Hobbitstein]

I've recently built an attenuator that is a copy of Regis Coyne's Ampwell House (Regis's Ampwell House Attenuator). My issue is as soon as I switch the attenuator on, with the attenuation set to 0, I lose a GOOD amount of volume. I play with a 15 watt Blackheart Handsome Devil, and the volume loss before I even turn the L-Pad is about the same as switching the amp from pentode to triode operation. Is this normal? I built this thing so I could dial back my volume just a bit at shows (I play with my amp dimed), not to give me a near 6db cut as soon as I turn it on. Any help would be appreciated. Thanks.

[hasserl]

Yeah, that's pretty much normal for those variable L-pads. Many/most other attenuators as well. Add a bypass switch to give you full power.

[Hobbitstein]

I have a bypass switch to go to full power. But the attenuation between "full bypass" and "on" may be more attenuation than I need. Then again, I'd really need to experiment with the volume levels in the bar, I suppose. Thanks for the quick response!

[Regis]

If you mean there is a dramatic drop in volume when the attenuator is turned all the way up, then you have a wiring error. There is an infinitesimal difference in volume when compared to total bypass with a switch, but it should not have a big drop like that. I've built a number of those attenuators and none of them do what you are describing. Double check your wiring against the diagram.

[Hobbitstein]

The wiring should be correct aside from I have lug 1 and 3 reversed on the L-Pad, so the volume acts in reverse. Would this cause the volume loss issue as well? I originally tested everything on a solid state amp so as not to hurt my tubes/OT, and there was no noticeable volume loss. Matter of fact, the volume loss only seems to be noticeable when the amp is dimed and the speaker starts to really breakup (I use a Greenback clone). I guess I gotta take it apart, regardless to double check everything. BTW, thanks for the design Regis! I even built mine in a coffee can, but went a bit more intricate with my graphics (as I'm a graphic designer by trade). My bandmates find it hilarious.

[Regis]

The wiring should be correct aside from I have lug 1 and 3 reversed on the L-Pad, so the volume acts in reverse. Would this cause the volume loss issue as well? I originally tested everything on a solid state amp so as not to hurt my tubes/OT, and there was no noticeable volume loss. Matter of fact, the volume loss only seems to be noticeable when the amp is dimed and the speaker starts to really breakup (I use a Greenback clone). I guess I gotta take it apart, regardless to double check everything. BTW, thanks for the design Regis! I even built mine in a coffee can, but went a bit more intricate with my graphics (as I'm a graphic designer by trade). My bandmates find it hilarious.

Exchanging lugs 1 and 3 should not cause your problem, I've done that too. You don't want to do that though, because the series resistor element has higher power handling capability than the shunt element and needs to be in its proper place. Swap those wires and see what happens.

I suppose it's possible you've got a bad L-Pad but I doubt it, I've built about ten of these things and never have had a problem. BTW, Hasserl helped with the design of this thing way back when, check out this thread.

I'd like to see a picture of yours.

[Hobbitstein]

I've actually read that thread, and still made your same mistake! Lol! I found that thread first, then your website after.

Here's a few pics of mine.