8 ohm amp -> 4 ohm attenuator -> 8 ohm speaker – asking for trouble?

[jimmywaleseswhale]

Hi,

My main amp is a Hughes & Kettner Statesman Dual EL84 20W – nice but loud! I'd like to use an attenuator to tame it a bit. The external speaker out is 8/16 ohm and the built-in speaker is 8 ohm.

I also have a THD Hot Plate attenuator (4ohm) which is meant to be very good but would lead to impedance mismatch (8/16 ohm amp -> 4 ohm attenuator). The THD FAQ seems to advise against it. The attenuator has a secondary speaker out and the FAQ suggests that I need to use the 4 ohm Hot Plate to drive two 8 ohm cabinets. I do have a secondary cab with an 8 ohm speaker but I honestly not sure I want a 2x12.

Might be a stupid idea but would it make sense to use the secondary out with a dummy 8 ohm load, while using the primary out into an 8 ohm speaker?

Alternatively, I have a 30W impedance-matching transformer so I could convert the amp out down to 4 ohm and swap the speaker to something 4 ohm but might be easier to find a different attenuator.

Finally, am I worried about the mismatch too much and should just use the 8 ohm amp -> 4 ohm attenuator -> 8 ohm speaker chain?

Thanks!

FAQ bits:

Q. Can I still use the Hot Plate if it has a different impedance than my amp?
A. ONLY if the impedance of the Hot Plate is EQUAL TO OR GREATER THAN that of the
amp. However, this will lessen the effectiveness of the Hot Plate’s tone controls.

II. AS A POWER ATTENUATOR TO TWO SPEAKER CABINETS:
Same as above, except connect cables from both speaker outputs on the Hot Plate to your
two speaker cabinets. These output jacks are wired in parallel, so if both speaker outputs
are being used, the 2Ω Hot Plate would be needed for two 4Ω speaker cabinets, the 4Ω
Hot plate for two 8Ω cabinets and the 8Ω Hot Plate for two 16Ω cabinets.

Impedance-matching transformer:
https://web.archive.org/web/20200226013 ... s-30W.html

[Reeltarded]

It's not a great idea. If you pretend you don't know better it will probably work until it doesn't.

The mismatch with multiply the 84 whirrrr. A lot. Do you want to dime this thing? I would not..

I use loads, always. I don't sweat too much about mismatching speaker loads 100% up or down, but I DO NOT MISMATCH LOAD BOXES TO OUTPUTS.

[jimmywaleseswhale]

Thanks for the reply! Any idea if putting an impedance matching transformer in front of the attenuator is still a bad idea? Not sure I'm that keen to search for a replacement 12' 4ohm speaker though

[brewdude]

Sell the 4 ohm attenuator and buy an 8 ohm attenuator?

[harleytech]

Sell the 4 ohm attenuator and buy an 8 ohm attenuator?

+1

[Reeltarded]

I was going to suggest a Power Soak but some idiot told everyone to jack the prices up 300% without reason.

[jimmywaleseswhale]

Sorry for a dumb question but is "Power Soak" a specific model? Bugera PS1 Power Soak?

[Reeltarded]

Oh no. Shultz. Old school and resistive.

[Littlewyan]

It depends on what the impedance matching transformer is for. Even if it was the correct transformer it could affect the tone of the amp and the whole set up would just be a bit over complicated.

Personally I would either replace the attenuator with an 8Ohm model or if you just want to tame the amp a bit you can build a very simple -6dB/-12dB attenuator with four resistors for not too much money.