Turning a 412 into a 112... ?

[Iron1]

I'm mulling over this idea of buying another 412 cab (there's a Marshall 412 at a pawn shop near me for sale with V30s in it for less than the speakers cost by themselves) but really don't want to power 4 speakers at once while in this townhouse.

But, we're buying a bigger house in the next year, where hopefully I'll have a basement studio set up and can run a 412 and not sonically annihilate the neighbors.

It got me thinking, what if I get the 412 and wire it so I can either use just 1 speaker or all 4?

Anyone ever done this? Pros/Cons? Dumb idea?

[James]

It's entirely possible. They're usually wired with two jack sockets on the back giving all speakers at 4ohms, stereo at 8ohms per side, or all speakers at 16ohms. There's nothing stopping you adding a switching socket (the kind that disconnects itself from the rest of the wiring when you insert a jack) inline with the wires to one of the speakers, which sould give you that one speaker at 4ohms. Assuming all of the speakers are 4ohms that is, but whipping the back off will confirm that

[Chris]

File it under "why the hell not"?

If you got that cab and this power amp for $300 you wouldn't even need to bother rewiring it. I had that amp for a while and it's awesome, and one of the huge upsides of modelers is volume control.

[Iron1]

It's entirely possible. They're usually wired with two jack sockets on the back giving all speakers at 4ohms, stereo at 8ohms per side, or all speakers at 16ohms. There's nothing stopping you adding a switching socket (the kind that disconnects itself from the rest of the wiring when you insert a jack) inline with the wires to one of the speakers, which sould give you that one speaker at 4ohms. Assuming all of the speakers are 4ohms that is, but whipping the back off will confirm that

That's what I was thinking - but I was also thinking sometimes I think wrong. And, I'll definitely take the back off before buying, just to make sure someone didn't yank the V30s and replace them with Marshall MGs or some such crap.

File it under "why the hell not"?

If you got that cab and this power amp for $300 you wouldn't even need to bother rewiring it. I had that amp for a while and it's awesome, and one of the huge upsides of modelers is volume control.

While not a bad idea, I'll use the cab for my Jet City - which I'm ordering some mods for today. Going to add a depth mod and the SLO OD circuit to it. Excited to hear how those turn out. And, if I want to run the Axe thru the 412, I can just run it into the "clean" channel or 4cm to the Jet...

[Tony]

That's what I was thinking - but I was also thinking sometimes I think wrong. And, I'll definitely take the back off before buying, just to make sure someone didn't yank the V30s and replace them with Marshall MGs or some such crap.



While not a bad idea, I'll use the cab for my Jet City - which I'm ordering some mods for today. Going to add a depth mod and the SLO OD circuit to it. Excited to hear how those turn out. And, if I want to run the Axe thru the 412, I can just run it into the "clean" channel or 4cm to the Jet...

As has been said its possible.

On your other bit. Ordering mods? Do you mean you're sending the amp off to get them done or getting mod kits? If it's the latter I can probably save you a good chunk of cash. The depth mod is literally a pot and cap.

The od mod is a little more involved but is still less than ten parts. The hardest part is changing the gain pot to 500k as they're pcb mounted.

Just difference I've found in the many I've modded is adding a choke. Helps the amp feel less stiff.

[Iron1]

Ordering mods? Do you mean you're sending the amp off to get them done or getting mod kits? If it's the latter I can probably save you a good chunk of cash. The depth mod is literally a pot and cap.

The od mod is a little more involved but is still less than ten parts. The hardest part is changing the gain pot to 500k as they're pcb mounted.

Just difference I've found in the many I've modded is adding a choke. Helps the amp feel less stiff.

This is what I'm looking at: https://www.epic-tone.com/online-sto...Mods-p87313337 Each kit comes with all the necessary parts and instructions to do them. $35 for the depth mod, $55 for the SLO OD and I just noticed they have a "Vari-Volt" which I believe allows you to emulate the 1/5/20watt switch Peavy puts on their MHs (waiting for clarification on that one).

Not sure my soldering skills are up to snuff when it comes to messing with PCBs, though.

[Tony]

This is what I'm looking at: https://www.epic-tone.com/online-sto...Mods-p87313337 Each kit comes with all the necessary parts and instructions to do them. $35 for the depth mod, $55 for the SLO OD and I just noticed they have a "Vari-Volt" which I believe allows you to emulate the 1/5/20watt switch Peavy puts on their MHs (waiting for clarification on that one).

Not sure my soldering skills are up to snuff when it comes to messing with PCBs, though.

Yeah those are pretty expensive for what you will be getting. About £10-15 worth of parts tops.

Instructions are handy though.

The jca22h is actually great for modding everything is through hole plated so you can do it without removing the board other than the pot which tbh isn't really necessary to be changed.

[JJ Rodriguez]

This is what I'm looking at: https://www.epic-tone.com/online-sto...Mods-p87313337 Each kit comes with all the necessary parts and instructions to do them. $35 for the depth mod, $55 for the SLO OD and I just noticed they have a "Vari-Volt" which I believe allows you to emulate the 1/5/20watt switch Peavy puts on their MHs (waiting for clarification on that one).

Not sure my soldering skills are up to snuff when it comes to messing with PCBs, though.

When soldering to PCBs, the trick is to use the lowest heat possible that will accomplish the task in the shortest amount of time possible. IE, you might want to use a slightly higher temp if it will flow everything and get it done quicker, but not so high you lift/burn traces and pads. Another key thing is keeping your iron clean, putting a dab of solder on the iron for better heat transfer, cleaning the area you're working, and using flux.

If you do lift/burn a trace, it's not the end of the world. I lifted a trace on my ADA MP-1 mod, I basically took the leg I had clipped off a resistor, bent it roughly to the shape of the trace, and soldered it to the ends/connections where that trace went.

[Leon]

I think the big thing to avoid when running a 4x12 as a 1x12 is removing speakers. I have a 4x12 that I wired up stereo, with one side V30's and the other Eminence Wizards. I found that I really liked one or the other (they didn't mix well for me), and running just two of the four speakers sounded good. But, if you were to pop a speaker out, you'll change the whole dynamic of the cabinet, and it doesn't sound good. I tried it with a 2x12 once... popped one speaker out, then decided I kinda wanted to pop both out, and wanted to check out the one speaker I still had it there, and it was... weird

Avatar has a nice replacement jack plate with stereo/monoseries/monoparallel options, though, to run just 1x12, you may need to do some math on the impedances.

[Leon]

That Avatar jack plate...

https://avatarspeakers.com/shop/parts/guitar-input/

[Tony]

That Avatar jack plate...
https://avatarspeakers.com/shop/parts/guitar-input/

Or if you want the same thing without the price gouging

https://www.amplifiedparts.com/products/jack-plate-plug-and-play-mono-stereo

[Leon]

Or if you want the same thing without the price gouging

https://www.amplifiedparts.com/produ...ay-mono-stereo

Definitely this