#1
I'm now building for a second time a cab for a friend as a favor. I'm totally cluless to the way I should wire this baby. He wants 2 V30s and 2 G12T-75s. He wants to have:

- 1 input for both V30s
- 1 input for both G12T-75s
- 1 input for all 4 speakers

I don't know if I should wire it in series or parallel..?!

Also can anyone please draw a schematic for this future-beast? This sould be done in about 2weeks. And, YES sound clips WILL be posted when it'll be built.

Thanks in advance!
#2
sounds like you just need to wire it the same way as the Marshall 4x12s, with the mono/Stereo switch. I'll look on my HDD for the schematic now
#3
We also need to know what the impedance of the speakers is and the impedance of his head. As well as if he only wants it to be switched between mono & stereo, or with 4-8-16ohm options

I apologize for the double post, I couldn't get edit to work when i accidentally submitted my above comment
#5
for 8 ohms, get all four speakers in 8 ohms, and wire the V30s in series, wire the G12T-75s in series, and then wire the pairs in parallel. that will give you 8 ohms.
Call me "Shot".

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#7
Quote by velly69
Thanks EC.

I think I need a chip to switch from mono -> stereo, or can it be done with 3 different input jacks?


You can't have both mono and stereo both as being 8 ohms.

Using four 4 ohm speakers with that configuration will give you 8 ohms to each channel if run in Stereo, 4 ohms in Mono mode. Similarly, using four 8 ohm speakers will give you 16 ohms to each channel if run in Stereo, 8 ohms in Mono mode.
"Everybody, one day will die and be forgotten. Act and behave in a way that will make life interesting and fun. Find a passion, form relationships, don't be afraid to get out there and fuck what everyone else thinks."
#9
Quote by velly69
How do I make it go fom Mono -> Stereo, do I need a switch for that?


Look at my post.
"Everybody, one day will die and be forgotten. Act and behave in a way that will make life interesting and fun. Find a passion, form relationships, don't be afraid to get out there and fuck what everyone else thinks."
#11
BAsically when the switch is in A position all four speakers are being powered by the left input. When in B. 2 Speakers are powered by each input.
#15
Nm

Use 4 8ohm speakers for best performance.
Last edited by Ashdownlover at Sep 27, 2007,
#17
No you will never use 1 set of speakers unless you use stereo mode with only one input. Also i doubt a 120 watt tube amp will blow two decent 12" speakers.

Some people use 2x12 cans at full power.
#18
^what's "decent" for you? cuz alnico speakers have low wattage load. more like 15~30 watts max. and with 120watt tube, you'd need at least two 60watt speakers. amp's wattage is when the amp is clean. when you push it THAT far, it goes over 120w when it clips. if that's a concern, he should get two 80watt speakers or something. but yes, it's possible that a 120watt tube amp will blow two decent 12" speakers.
Call me "Shot".

ShotRod Guitar Works

Custom Hand-wired Amplifiers and Effect Pedals.

Est. 2007


Source to everything I say about Guitars, Pedals, and Amplifiers: I make them.


UG's Best DIY PedalBoard
#20
Quote by velly69
One set are Celestion V30's, 60W, while the others are G12T-75's, which are 75W. Both being 12".

As long as the speakers don't clip, there's no harm done, right?


Guitar speakers (unlike hi-fi speakers) are designed to be able to clip occasionally without doing too much damage. Your head will be putting out more than 120W when it's turned way up, so 120W might be slightly overpowering the V30's. You may just have to keep it turned down. What I'd be looking more to do is have a V30 and a G12T-75 on each side so you've got a slight amount of headroom to work with. There's If you're running the amp in stereo and you've got a different load on each channel, some amps won't like this at all.
"Everybody, one day will die and be forgotten. Act and behave in a way that will make life interesting and fun. Find a passion, form relationships, don't be afraid to get out there and fuck what everyone else thinks."
#21
wire it so its one of each type of speaker on each side as The Random Hero said.. Ive seen a few people use this method and they say they are very happy with it.

And thinking about it i remeber hearing somewhere a marshall was putting out 160 watts at full bore. Dont know if it was true but its a good idea to keep in mind.
#22
That's what I plan on doing, wiring in an X shape.

Quote by Ashdownlover

And thinking about it i remeber hearing somewhere a marshall was putting out 160 watts at full bore. Dont know if it was true but its a good idea to keep in mind.


What's that expression mean?
#23
At full bore is everyhting maxed out like gain and volume but still maintaining a good tone. Tube amps are funny just keep that in mind. While they say 120 watts RMS it sure as hell beats a 120 watt RMS solid state amp.