dual l-pads

[jrhoden]

when making an attenuator for a 100 watt tube amp how do i go doing that?
do i just wire the two together?

anyone have a layout for it?

thanks

[Ripthorn]

ampgarage.com has plans for several DIY attenuators.

[Taylor]

I don't believe you can make an attenuator for a 100w tube amp using l-pads. I looked into this for some time, because I wanted to open up my 100w Univox without getting evicted.

It seems that this won't work for a number of reasons, which I don't remember with enough clarity to tell you. Bill Fitzmaurice, an electrical engineer and speaker designer, told me that L-pads won't handle that much power.

If you want to build an attenuator for a 100w amp, you'll need a 150w rheostat and some huge resistors - there are calculators that tell you the values of the resistors. The bummer is that the rheostat alone costs between $60 and $80:

http://www.mouser.com/Search/Refine.aspx?Keyword=150w+rheostat

Weber sells a kit:

https://taweber.powweb.com/store/kits_weber.htm#Atten

which, unlike stompbox kits, is not much more than the individual parts would cost you.

Remember if you decide to roll your own that your amp will put out more than its rated power when it's cranked up to full, so you must use parts rated for around 150w-200w if you plan to use this with your amp at 10.

[jrhoden]

thanks taylor...

uhmmm ampgarage.. nah.....no help

im NOT interested in 15watt and 50 watt attenuators........period

thanks anyway

[MarcoMike]

what about pulling out a couple of power tubes to begin with?

[Taylor]

Yes, you can do that in many amps, but the problem is that, you often get a reduction of less than half the power, and even half the power would only be a 3dB volume drop, which is barely perceptible.

Here's a thread where I asked the same thing:

http://www.talkbass.com/forum/showthread.php?t=501868

One thing I missed in there is that, although taking 2 tubes out might not make an appreciable difference in volume, it will make building an attenuator easier, since your attenuator only needs to handle half as much power as before.

[svstee]

On option is a fixed power attenuator, one built without the rheostat. The disadvantage is obvious, but it might be your best bet if you think you can figure out a reduction that is OK to stick with. Keep in mind decibel reduction is not a linear drop in volume.

[jrhoden]

yeah ive heard that also...pulling two tubes out

ive got a mark IIc with 4 6l6's   -- 60 watt/100watt hell even the 60 watt is freekn LOUUUUD! lol...so that may not be a bad idea....
if i have it set on 60 watt what wqould it take it down to by removing 2 tubes?
it wont hurt anything to pull two of them and keep the el34's will it?

i saw this  on one of the attenuators on ebay
this is for an attenuator not a volume control...

The OUTPUT TAMER can be used on a 100 watt amplifier ONLY if you do not exceed 30% of your amplifier's maximum power output. This means keeping your amplifier's master volume below 3 on the dial and then use the OUTPUT TAMER to control your volume level. OR, if your amp is NOT Class A and runs four output tubes, you can remove the two outer or two inner tubes to reduce the output to approximately 50 watts. Then the TAMER can handle your amp's output. This "trick" is safe for all Class A/B amps.

[Projectile]

The Trainwreck "Dr. Z Aibrake" will work with 100watt amps, or at least that's what they claim in their literature.

I took a bunch of detailed gutshots of my old Trainwreck Airbrake and threw them into a folder with some stuff I found on the internet relating to different versions. It's really unorganized, but there should be more than enough information there for someone to build their own power attenuator:

http://www.speedyshare.com/130845309.html

Link won't last forever, so grab it while you can.

[jrhoden]

got it...thanks