DIY 100w attenuator bright switch

[Mattallica]

I recently built the 2-stage 100w attenuator outlined in the link below, and it works a treat! Very night-and-day volume cut, I recommend this to anyone with a 100w tube amp who is stuck dialing in the master from 0-1/etc. It's simple to build and I estimate I spent $50-60 total on everything. Very well worth it.

I'd like to build another one however, with two improvements:

1. Cut it down to one switch. The single -6db cut is perfectly adequate for me, the -12 db cut with both engaged is almost "too" quiet for practical jamming use.

2. Add a "bright switch", even with just one -6 db cut engaged, some of the highs and "bite" are lost, not really bad at all but enough to notice.

How would I go about modifying the circuit to achieve this?

If anyone is curious, I'm using it with a mid-late 70's Marshall Master Volume JMP 100 watt.

Here is the link to the build guide: http://www.hearditontheweb.com/images/pdf/attenuator.pdf

Thanks duders!

[midwayfair]

Did you run out of room on the treble knob on your amp, or are you trying to keep the same settings? Sorry for the snarky answer, but people rarely max out their treble knobs and it's not exactly easy or safe to do what you're asking or it would have been incorporated in the design in the first place.

[Mattallica]

No problem, and thanks for the reply!

With the attenuator engaged, the treble knob stops making a difference at around 4-5, but the overall high-end is cut as well. It's hard to explain without listening in person, but there is a difference. The sweep on the Master is MUCH improved and more useable to dial in at an appropriate volume, but I'm losing some of the "bite and snarl" I get with a .68uf cap on the Prescence knob of the amp with the attenuator engaged, hence my thought to add a bright switch of some sort.

[midwayfair]

Part of it's just the pure volume difference; at lower volume the bass and upper treble ranges of sounds are harder to hear. Part of it is that if you're turning up the gain you're getting more distortion -- and hence less bandwidth -- at the same volume level.

You can also turn down the bass.

There's not a safe way to add a high pass to the attenuator itself. You need to find a way to add treble/cut bass & midrange BEFORE you get to the power tube outputs.

[jtaormina]

some of the Webber attenuators have tone controls. The more expensive ones get more elaborate. But this link for the mini mass schem has a bright switch.

http://freestompboxes.org/members/soulsonic/schematic/WeberMiniMASS.gif