4x12 with 4 different speakers?

[ettepostkonto]

selloutrr - help!

Won't this last version just result in a polarity switch - not a switch from parallell to series...?

[rdjones]

Won't this last version just result in a polarity switch - not a switch from parallell to series...?

This should work for series/parallel.

Note that there are several switch combinations that will result in an open circuit.

rd

[ettepostkonto]

Thanks once again!

Yes when all switches are off it's an open circuit - but when else?

Isn't the danger rather getting a 32 ohm load in series mode if one speaker is on in "group A" (i.e. speaker 1 or 2) and one in "group B" (speaker 3 or 4).

If I only use it like this - I should be fine:

1. Parallel - any of the 4 speakers individually (16 ohm) or in pairs (8 ohm)

2. Switched to series - ALWAYS all 4 speakers (16 ohm) and NEVER else.

...right?

[selloutrr]

the danger is any ohm load that is not matching the amp you are running with it. general rule miss matching impedance can cause damage. I would also build in the test points and meter it before hooking it up.

I STRESS THIS IS A BAD IDEA! AND NOT THE WAY TO DEMO SPEAKERS.

[ettepostkonto]

You're just jealous

Seriously - I'm going ahead with it anyway. Can't afford/can't be bothered with the hassle of lugging 4 separate 1x12 cabs...

And shouldn't I be able to measure it up at the jack before I use it?

What would be helpful now is a confirmation that this latest mutation of the circuit will do what I want it to:

1) Will it let me run any of the speakers separately (16 ohm) or in tandem with any of the other speakers (8 ohm) in parallel mode?

2) Will it give me a 16 ohm load with the switch set to series and all speakers activated?

Thanks to all of you for your input!

[vibratoking]

The total load of any N resistive loads in parallel is 1/(1/R1+1/R2+...+1/RN)

The total load of any N resistive loads in series is R1+R2+...+RN.

I assume you know how a switch works.

With the two equations listed above and the knowledge of how a switch works, you can answer you own questions and move forward with your design. Have fun.

[rdjones]

What would be helpful now is a confirmation that this latest mutation of the circuit will do what I want it to:

1) Will it let me run any of the speakers separately (16 ohm) or in tandem with any of the other speakers (8 ohm) in parallel mode?

2) Will it give me a 16 ohm load with the switch set to series and all speakers activated?

1) Yes
2) Yes

Does the amp not have a 4 Ohm tap ?
That would simplify this to a great degree.

rd

[rdjones]

Yes when all switches are off it's an open circuit - but when else?

When both speakers are switched off in either "group" and the series mode is selected.

Isn't the danger rather getting a 32 ohm load in series mode if one speaker is on in "group A" (i.e. speaker 1 or 2) and one in "group B" (speaker 3 or 4).

Yes, but that's a much lesser evil than an open for tube amp, assuming a 16 Ohm output.
Solid state doesn't care.
I'm still uncertain about what amp or even type of amp is in question ...

If I only use it like this - I should be fine:

1. Parallel - any of the 4 speakers individually (16 ohm) or in pairs (8 ohm)

2. Switched to series - ALWAYS all 4 speakers (16 ohm) and NEVER else.

...right?

An amp with a impedance switch would go a long way toward simplifying this greatly, without the associated risk of possible opens.

reddog

[selloutrr]

putting the amp in standby when switching speakers is a must. otherwise.. please video it and put it on youtube.

[ettepostkonto]

Thanks guys!

No - none of my amps has a 4 ohm tap, they're all 8- or 16 ohm...

Amps are all tube amps:

• Fender DRRI (which is the only one that can handle a 4 ohm load - if I disconnect the internal speaker)
  Vox AC15H1TV
  Marshall 1974X
  Gibson GA-15RV
  And looking to buy a Ceriatone 5E3 head

Youtube - will try to do that!

[ettepostkonto]

One more thing - which way is "up" on the middle switch, left or right, if I want it to be in standard paralell mode (4 ohm) when the toggle is in the up position, and series/paralell (16 ohm) when engaged (toggle down)?

[selloutrr]

It would depend on which way you wire the back of the switch. You understand how a switch functions right? If not get out your meter and test continuity before you solder. build it and re check it with a meter if you have doubt in your work. Wire multiples of the same switch the same way so they all work in the same direction.

[ettepostkonto]

Yeah I know how a switch works. Just want to make sure before I solder, so I get it right and don't have to redo it...

Left on the middle switch in this diagram is up ...right?

[selloutrr]

It is if that is how you wire the switch.

Trace continuity.. place the switch in the direction you want it.. solder the wires to give the desired result.

It's that easy.

If you have doubt try using aligator clips until you have a better understanding of what it is you are doing. Once you are happy solder it in place.

If you can't do it.
I'll sell you one of my prebuilt switchers for $350

[ettepostkonto]

What I mean, selloutrr, is - if I wire the middle switch like it is shown in the diagram, will the left hand side turned clockwise 90 degrees get the result I describe?

(I take it for granted that we're viewing the switches from behind - i.e. the lugs.)