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DeFrag
Moderator
USA
3409 Posts |
 Posted - 01/08/2008 : 19:54:37
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I'm making my own cab switcher with a 4PDT switch rated at 10A@250V or 6A@125V. Since I don't know how much current a typical Class-A 15W or Class-A/B 50W amplifier head puts out, I think the switch should handle it, but...
What wire size should I use inside the pedal for speaker-level current?
(#20 or #22 is standard for low or line-level signals in regular effects boxes.)
TIA  |
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pedals 4 pv
Platinum Member
Canada
1351 Posts |
Posted - 01/08/2008 : 23:15:36
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Hi DeFrag
The output voltages should be marked on the amplifiers in question. These voltages are typically between 20 and 30 volts AC rms. Wattage is the product of Voltage X Current. Inversely, watts/volts = current in amperes. Once you have determined your current values, consult the chart in the link below to determine your wire size. It's OK to use larger wire if there is room.
http://www.powerstream.com/Wire_Size.htm
If the wire is to be inside of a pedal, the length of the wires will be fairly short, so the IR loss in the wires will be negligable and can be disregarded in your calculations. I hope this helps, DeFrag, if you have any problems E-mail me |
Edited by - pedals 4 pv on 01/08/2008 23:27:35 |
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DeFrag
Moderator
USA
3409 Posts |
Posted - 01/09/2008 : 03:41:51
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Tks pedals; good link. Unfortunately none of my amps specify output voltages.
I was going to use the Mesa at 100W / your high estimate of 30VAC RMS = 3.33 amps & lookup in the table. I should use the "Maximum amps for power transmission" instead of "Maximum amps for chassis wiring" right? It comes out to 16-gauge which is what a tube amp repair tech told me today.
I suppose I could have my son play while I hold a meter on the speaker terminals to read the voltages a bit more accurately than using your 30VAC RMS. What do you think about this?
The thing is.. I WON'T be using the switchbox for the Mesa, rather I'll be using the Orange head & the Blackheart. But I think if use 16-ga I should be able to use the switchbox for the Mesa down the road if I ever needed to. 18-ga should be fine too considering the fact that output is very rarely continuous & peaks are transient. Would you agree that 18-ga should work alright?
In a nutshell, when I play the Orange head, it'll run the Orange 1x12 cab & the Blackheart cab too. When I play the Blackheart Combo amp, it'll use its built-in 1x12 & the Orange cab as well. The 4PDT switch simply isolates the heads from each other & I only plan on running one at a time. Additionally, I've learned from Radial Engineering that their Cabbone & Switchbone products buffer & cross-fade (or ramp) the outputs so each tube amp's speaker sees the proper load characteristics during switching. Thus, I will NOT be switching from the Orange to the Blackheart on the fly.
The impedances are ideal for me to run these two 12" speakers simultaneously with each amp at a time though. Since the Orange cab is closed-back with a V30 & the Blackheart combo amp is open-backed with a Celestion Eminence, they should strong & directional, yet with presence when run together.
Tks for your help mate. I'm listening if you have any other comments or recommendations. 
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Edited by - DeFrag on 01/09/2008 04:10:14 |
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pedals 4 pv
Platinum Member
Canada
1351 Posts |
Posted - 01/09/2008 : 04:34:57
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| Bigger the better for speaker wire DeFrag, I should have been more clear that chart is the minimum size to carry the current. the Maximum amps for chassis wiring would be for inside the pedal and the Maximum amps for power transmission would be for the speaker wire this means that you can't use any smaller wire than that. That should be a pretty cool set up when its done. |
Edited by - pedals 4 pv on 01/09/2008 05:34:57 |
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Wire size for Project Cab Switcher
