Simulating Speaker Impedance Mismatch

Cliff Notes are small yellow guidebooks written by experts to help explain academic subjects to people who need a little help, or don't have the time to read and study the actual lesson material.
 
Cliff Notes are small yellow guidebooks written by experts to help explain academic subjects to people who need a little help, or don't have the time to read and study the actual lesson material.

I'd not have passed the third grade without them...:shock
 
Cliff Notes are small yellow guidebooks written by experts to help explain academic subjects to people who need a little help, or don't have the time to read and study the actual lesson material.

I think of them more as top-down, 'let's not grub for our porridge', writings. Also, undeniably, Cliff takes pleasure in imparting these things.


I'd not have passed the third grade without them...:shock

I don't know as it would've made any difference for me at that time if I'd had access to them. Conventionally speaking, they shouldn't have passed me.
 
I used to own an early '90s THD Electronics Plexi head (the serial number was my name - pre-production) and the output transformer was built I safely accept any impedance load16th 2ohm to 16ohm on either impedance setting (2/4ohm & 8/16ohm). This was a very useful feature. My favorite way to run the amp was through a 16ohm speaker load (Marshall basketweave 4x12 w/ oem 50watt Celestions) on the 2/4 ohm tap. That amp hands down the best Marshall type amp I'd ever Played.

.....until the AxeFX II came along!!
 
BTW, for this to be audible the Master Volume needs to be set very high so that you are clipping the (virtual) output tubes.

Most amps set the impedance ratio of the OT so as to get maximum power from the power tubes (within the SOA). Some amps intentionally mismatch the OT to give more control over the distortion by riding the volume control, i.e. Trainwrecks.

Most amps actually slightly undermatch the OT as the speaker impedance is greater than nominal outside of the midband. Trainwrecks are overmatched.
 
Guitar folklore has it that SRV and Joe Walsh intentionally mismatched their speaker impedance. I imagine others have done this. The general idea is you plug an 8-ohm speaker into the 4-ohm jack or vice-versa.

The Axe-Fx allows you to replicate this behavior using the Transformer Match control. To simulate plugging an 8-ohm speaker into the 4-ohm jack set Transformer Match to twice it's current setting (i.e. 2.0). For the other way around set it to half (i.e. 0.5).

BTW, for this to be audible the Master Volume needs to be set very high so that you are clipping the (virtual) output tubes.

Most amps set the impedance ratio of the OT so as to get maximum power from the power tubes (within the SOA). Some amps intentionally mismatch the OT to give more control over the distortion by riding the volume control, i.e. Trainwrecks.

Most amps actually slightly undermatch the OT as the speaker impedance is greater than nominal outside of the midband. Trainwrecks are overmatched.

This is not folklore....
I saw Joe Walsh many years ago at the Chesterland Hullabaloo here in Ohio, back when he was with playing ‘The James Gang’. ....You wanna talk about ‘Speaker Impedance Mismatch’ ?...


To my horror as he was setting up for the show, I watched Joe with much anticipation as he pluged the SPEAKER OUTPUT of one Fender Twin into the (front) INPUT of another Fender Twin .. He sounded really great for about 1 minute give or take, until the amp(s) started smoking and caught on fire. What a show that was! So much for that brilliant idea... :lol
 
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This is not folklore....
I saw Joe Walsh many years ago at the Chesterland Hullabaloo here in Ohio, back when he was with playing ‘The James Gang’. ....You wanna talk about ‘Speaker Impedance Mismatch’ ?...


To my horror as he was setting up for the show, I watched Joe with much anticipation as he pluged the SPEAKER OUTPUT of one Fender Twin into the (front) INPUT of another Fender Twin .. He sounded really great for about 1 minute give or take, until the amp(s) started smoking and caught on fire. What a show that was! So much for that brilliant idea... :lol

I've actually done (almost) that very same thing plugging my Mesa slave output into the low impedance input jack of my JC-120. Only blew out the Mesa's filter caps once in 30 years! ;)

PS - love Joe Walsh & Games Gang!
 
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