Anyone know how to turn a 4x12 4ohm into an 8ohm or 16ohm?

B

Bman

Power User
I have a cab that’s 4ohm but my amps are 8ohm. I’m itching to hear my Axe3 thru a 4x12.

I know I can rewire it to stereo and do 8ohm to each jack. But the amp is a Marshall DSL and I’ll be using it as an extension speaker, and run the Axe3 thru the FX in.
 
unix-guy said:
@Bman - did you update your post title? I don't remember seeing 16ohm in the title when I replied.
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You know, I don't recall but a 16ohm would work too. I believe I can run an 8ohm output into a 16ohm cab, can I not? Also, I believe if I leave the combo speaker plugged in (it's a 8ohm Creamback) the output to the extension becomes a 16ohm output. I'll verify with the DSL40's manual, but I thought that to be the case.

So another question or observation maybe? Will a 16ohm signal be quieter than a 4ohm or more importantly will there be a difference in 'tone'? The cab is a cheap cab but sounds really good when I paired with my old '73 Marshall 50 watt. The inefficient speakers must have some mojo working.

Edit: A quick search and the answers vary on tone. It's in the ears and may 'feel' different. Since this is a setup that I've never experienced (Axe3,DSL40 powr section, cab) I won't have a clue and only know what I hear. Thanks for the quick responses. Unfortunately, it'll be a quick experiment because I don't want to piss of the neighbors. I'm totally fine with my FRFR setup. I just miss the oomph and want to scratch that itch.
 
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I have all my speaker cabs wired selectable 4/16 mono or 2x8 ohms stereo, which is a fairly common selection when using 8 Ohm speakers. With the Axe FX and power amp, my preference is 16 ohms but it depends upon a number of things, so ymmv. You may find 16 better for rock and 4 better for cleans, depending on taste.
 
Bman said:
You know, I don't recall but a 16ohm would work too. I believe I can run an 8ohm output into a 16ohm cab, can I not? Also, I believe if I leave the combo speaker plugged in (it's a 8ohm Creamback) the output to the extension becomes a 16ohm output. I'll verify with the DSL40's manual, but I thought that to be the case.

So another question or observation maybe? Will a 16ohm signal be quieter than a 4ohm or more importantly will there be a difference in 'tone'? The cab is a cheap cab but sounds really good when I paired with my old '73 Marshall 50 watt. The inefficient speakers must have some mojo working.

Edit: A quick search and the answers vary on tone. It's in the ears and may 'feel' different. Since this is a setup that I've never experienced (Axe3,DSL40 powr section, cab) I won't have a clue and only know what I hear. Thanks for the quick responses. Unfortunately, it'll be a quick experiment because I don't want to piss of the neighbors. I'm totally fine with my FRFR setup. I just miss the oomph and want to scratch that itch.
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Generally most tube amps can tolerate a slight mismatch (one rating higher or lower), but it depends on how robust the amp and output transformer are. If you are going to mismatch, plugging into a lower than expected load is typically "safer". The lower load means more current can flow in the secondary and speaker coil, but the rest of the amp circuit can only supply so much power, so it is sort of self limiting to a degree.

Higher than expected load means less current can flow through the speaker than expected and that mismatch causes fly-back voltage on the primary side of the output transformer. If it's bad enough, it can cause the transformer windings to arc and burn out the tranny. That's why having no speaker plugged in is so bad. That's essentially an infinite load and no secondary current can flow. All that power has to go somewhere, so it basically bounces back into the amp circuit and smoke and expensive repair bills result.

Safest bet and best performance is always with a proper impedance match.
 
mr_fender said:
Generally most tube amps can tolerate a slight mismatch (one rating higher or lower), but it depends on how robust the amp and output transformer are. If you are going to mismatch, plugging into a lower than expected load is typically "safer". The lower load means more current can flow in the secondary and speaker coil, but the rest of the amp circuit can only supply so much power, so it is sort of self limiting to a degree.

Higher than expected load means less current can flow through the speaker than expected and that mismatch causes fly-back voltage on the primary side of the output transformer. If it's bad enough, it can cause the transformer windings to arc and burn out the tranny. That's why having no speaker plugged in is so bad. That's essentially an infinite load and no secondary current can flow. All that power has to go somewhere, so it basically bounces back into the amp circuit and smoke and expensive repair bills result.

Safest bet and best performance is always with a proper impedance match.
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I found this article from H & K:
http://blog.hughes-and-kettner.com/ohm-cooking-101-understanding-amps-speakers-and-impedance/
Running 16 a ohm cab with an amp expecting 8 ohms is fine. Just don't go more than double the amp's expected ohm load.
 
I think I got it right. But I'm afraid to crank until I get verification. It works. Sounds like ass with the DSL at low levels, except for the clean channel. DLS's have a ratty pre-amp tone. You have to cook the power section and bring in the pre-amp fuzz to mold the tone.

Once I get some verification, I wanna try my AXEfx3. Friedman preamp, no power amp and not cab sim...into the FX in
 

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The 4x12 looks to be wired in series-parallel for a total load of 4 ohms. Are those neo speakers? The magnets are tiny.

If you want 16 ohms you'll need to wire them in full series where the + of the jack connects to the + of the first speaker and the - of the first speaker goes the to the + of the next speaker and so one until the - of the last speaker connects to the - of the jack.

There's no way to wire four 4 ohm speakers to get an 8 ohm total load.

Which version of the DSL40 combo do you have? The output options have changed over the years. Old ones had 3 speaker jacks while the new ones have 5.
 
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mr_fender said:
The 4x12 looks to be wired in series-parallel for a total load of 4 ohms. Are those neo speakers? The magnets are tiny.

If you want 16 ohms you'll need to wire them in full series where the + of the jack connects to the + of the first speaker and the - of the first speaker goes the to the + of the next speaker and so one until the - of the last speaker connects to the - of the jack.

There's no way to wire four 4 ohm speakers to get an 8 ohm total load.

Which version of the DSL40 combo do you have? The output options have changed over the years. Old ones had 3 speaker jacks while the new ones have 5.
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Crap. So I had it backwards?

it’s an old crate cab from the late 80s W/ 12watt speakers. It sounded glorious with my old Marshall.

I’ve got the oldee DSL40 w 3 speaker outputs. I dialed up a Friedman and JMP-1 pre amp and jammed thru the 65watt creamback. It’s usable and blows away the pre-amp in the real amp. But after about 5 minutes I went back to FRFR. If I ever need it for a back line I might consider using it. It’s LOUD.
 
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