Can I run my Quantum at 4 ohms?

megadan

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I have a Guild Thunderbass/Quantum head.

It is super :)

I noticed that the speaker jack noted that the proper impedance was 8 ohms.

But it also has an ext speaker jack on the other side, also 8 ohms.

At first I thought that the amp had two different transformers or two taps or whatever, and I never put a load lower than 8 ohms on either tap (used to use 8 ohm cabs, each plugged into a socket).

Now my main gigging amp (the Guild is mostly for recording, it's pretty old) has blown and needs to be repaired.

In the meantime it would be nice to run the Guild and not have to borrow someone elses head. The cab I use now is an Ampeg 610HLF, which is a 4 ohm cab.


I'm now thinking that maybe that ext cab jack on the Guild is just a regular second speaker jack like on modern amps. If this was the case, I could run a 4 ohm load from the main out, right? Do you think this would be ok?
Would I have to short or put a blank plug in the ext speaker out to make it work?

Thanks in advance.
 

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If you had 2 8 ohm speaker cabs plugged into your head, the total load would be 4 ohms, so, you're golden with the 4 ohm cab.
Don't plug another cab into the extension jack, as this would drop the load too low.
A 4 ohm and another 4 ohm cabinet would drop the speaker impedance to 2 ohms and you would run the risk of blowing the output transformer- not fun!
 
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