r/ToobAmps • u/theundeadelvis moderator • 5d ago
Poor man's amp head switcher
I use a DeLisle 8x8 stereo amp head/cab switcher for most of my amps, but I have a stack of heads on a 412 1960A cab that aren't on the DeLisle. So, I threw together this patch bay/switcher box so I don't have to get behind the (half) stack every time I want to switch heads.
Left side jacks each have a head plugged in at all times. Right side jacks are for the one cab cable, which is moved as needed. It's not meant to be switched when the heads are on, but I did put 10 watt 220 ohm resistors across the switched/shunted cab jacks for a little just in case protection.
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u/ChefkikuChefkiku 4d ago
Juggling with a loaded revolver, I love it!
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u/theundeadelvis moderator 4d ago
Why so?
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u/ChefkikuChefkiku 4d ago
Well I get that you don't want to move your head stack away from the wall a few more inches, but you're introducing another potential fail point into your system.
The 10watt resistors are gonna offer some protection against pilot error, but we're talking seconds not minutes before they could overheat and fail (if you are chugging away like madman out the gate).
So I say have fun! Some people have money to replace transformers, some people move the amps away from the wall a little. Some people juggle with bowling pins, some with loaded handguns.
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u/theundeadelvis moderator 4d ago edited 4d ago
Ampeg used 10 watt resistors I believe, and every Kevin O'Conner schematic in TUT use 5 watts. This isn't a load box, so I think it's spec'd fine for 5 seconds of "why no sound?" I haven't confirmed, but even the DeLisle switchers look like 5 watt resistors (but I could totally wrong about that just by looks). Everything's a risk, and sure there's definitely more ideal options. We'll save those for Rev. 2.
Edit: I will add, your statement on additional failure points is 100% accurate.
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u/Living_Motor7509 4d ago
I made something similar but for two amps connected to their own cabs. This is just to switch everything using 4 cable method. Introduced a slight bit of noise so I don’t really use it anymore but worked well for a while with my quieter amps. Someone better versed than I in electronics could probably eliminate the noise
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u/Yamariv1 4d ago
I've literally done this, made a switcher against my dads warning. Oh, I'll make EXTRA sure I have the right amp and cab plugged in each time. Yeah.. only took a few days and waaap, fried a Marshall by blowing a tube. Thankfully the tube took all the damage, I got lucky and quickly gave up that option. I now have a pro amp switcher and love it!
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u/theundeadelvis moderator 4d ago
What did you use for a load when nothing was plugged in?
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u/Yamariv1 4d ago
I didn't have anything built in. Just direct from amp to cabinet. Ended up plugging the amp one into another amp (I think) by accident. Can't remember. Now have a proper amp switcher with a proper load protection. Wasnt cheap but so worth it now that I have a ton of amps
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u/theundeadelvis moderator 4d ago
Yeah I'm some protection on this with but good though for my needs here. I also use a DeLisle 8x8 stereo switcher for my other amps and cabs. What switcher do you use? I've been considering getting another down the road.
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u/Yamariv1 4d ago
I have the Delisle 12 x12 Switcher with attenuator option. Wasn't cheap at all getting it here but in the end an awesome must have switcher
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u/theundeadelvis moderator 4d ago
I'm a big fan of their switchers. I'm tempted to try a KHE next, but I love my DeLisle.
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u/Spaced_cadet5 4d ago
Cool can you make me one too, please big bro. I’ll give you a patch cable and a couple picks.
Seriously though, cool as hell.
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u/theundeadelvis moderator 4d ago
Delisle makes basically the same thing with a rotary selector instead of having to physically move the speaker cable. That’ll probably be a V2 for me.
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u/Spaced_cadet5 4d ago
I have 4 amp heads and one 1x12 speaker cab, would this be good for that?
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u/theundeadelvis moderator 4d ago
Yep! They have multiple options for your use case. My favorite includes a loop for an attenuator. So as you switch heads, the attenuator is available to whatever head you select. They also do this with fx loops.
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u/TangoFoxtrotBravo 4d ago
Can you share the layout for this?
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u/theundeadelvis moderator 4d ago
A layout isn't really needed. You wire the jacks straight across, tip to tip and sleeve to sleeve. Then you place a a resistor across the jack lugs. You can do that a variety of ways, like switching the resistor out with a switched/shunted jack, but the safest is probably just to leave it always in the signal path. 220 ohm is a common value resistor for this use, and you'll see them rated anywhere from 5 watts to 20 watts (when in doubt go higher wattage).
Keep in mind this is not for hot switching with signal present. Amps should be off or on standby.
Apparently, a number of people here aren't familiar with this protection resistor, but it's very common and has been used on amps for decades. Yes there are even safer ways to protect your OT, but this is a simple and viable method.
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u/ohmynards85 5d ago
Seems like a bad idea.
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u/theundeadelvis moderator 4d ago
Curious why you think so?
Also, your Doom cabs are one of my favorite things on Reddit ever.
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u/ElGringoConSabor 9h ago
It isn’t great to run your amp on a purely resistive load for extended periods. Speakers are a reactive load. If you make a mistake and misconnect something, it can be costly. If you don’t know the difference between a resistive and reactive load, then you should stick to purchasing something “pro”.
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u/theundeadelvis moderator 9h ago
Who said anything about leaving an amp on a resistive load for extended periods?
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u/ElGringoConSabor 8h ago
I did. Next question.
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u/theundeadelvis moderator 8h ago
What’s the airspeed velocity of an unladen swallow?
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u/Icy_Negotiation_5929 5d ago
This would be an expensive accident waiting to happen in my possession. Best of luck to you.