Fixed Attentuation On A Speaker Cab?

[doveman]

I would like to back off a 2x10 speaker cabinet just a bit 3-4 db when it's running in parallel with a 1x12 cabinet. I don't really need adjustable attentuation. Maybe a DPDT switch and a LPad (Driver Attenuation Circuit). This appears to be one resistor between the speaker (R2) and one on one the + lead (R1). I found a place that has a calculator where you put in the Ohms and required db attenuation and it gives you the values of the resistors. For example:

Z = 8 Ohms
A = 3 db
Resistors Needed = R1 = 2.34 Ohms & R2 = 19.39 Ohms

Z = 8 Ohms
A = 4 db
Resistors Needed = R1 = 2.95 Ohms & R2 = 13.68 Ohms

My questions:
- Does this work well?
- What kind of resistors would you use for 35 watt amp. (When it's being used in parallel the amp power would be roughly half that ... not talking a big amp.)
- How would you get these specific values ... how close can you be I wonder?

I have an old Altair that works OK with the 4db setting for me but just curious ... lot of weight to carry around just to use the first setting.

[Structo]

Not sure this will help Ken, but -3db is 50% less power.

Check out the Airbrake without Rheostat in the Trainwreck section.

It is a attenuator made from power resistors with multiple taps.

[greiswig]

You don't mention what impedances your cabinets are currently wired at, whether you have the 2x10 wired as a parallel cab now, and what your OT impedance options are.

If you have the 2x10 wired in parallel, then putting a switch in to put them in series when working with the 1x12 would probably get you about where you want, provided the overall impedance is something your OT can handle.

[doveman]

Both cabs are 8 ohms ... the 2x10 being two parallel 16 ohm speakers. I tried the old Altair attenuator on it's first setting -4db to take the edge off the 2x10 and give the 1x12 a bit more dominance. Worked well I think.

It didn't seem to be 50% though ... just a bit less ... maybe the settings are not truly db. But the attenuators I've seen are labeled to about 10 db. This altair goes up to 44.

[doveman]

Here's a link at Weber I found that describes what I'm talking about ...

http://www.webervst.com/lpad.htm

Also, my D'Lite has 4, 8 and 16 ohm options ... I usually run the two 8 ohm cabinets in parallel on the 4 ohm setting. I'd just like to take a bit off the 2x10 to even out the two sounds a bit.

[selloutrr]

it sounds like it would be more versatile as an external device. they get very hot!!! like after a 2hr show you could warm pizza. I'm not sure how your running the cabinets if you have dual speaker outputs from the head at which point you could just insert the power sucking load on the cabinet line you want to bring down. if it's a threw cabinet patch i've never tried it but i guess you could put the softer cabinet first in the chain then patch out to the load box and then to the cabinet you want to attentuate since it's just a threw jack. Their are about 15 difference company's making different attenuators all claiming to be the best at what they do. just make sure they offer the right Ohm load on the input as well as the output of the device and try to buy a used model so if you hate it then you can resell it with little to no loss. and if you love it then you got a great deal! better yet make friends with a guy who has one and try it before you buy it.