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Help answer my non-technical questions...

speyer

speyer

Supporting Member
Oct 14, 2006
2,805
1,840
Bowen Island, CANADA/Blaine WA, USA
#1
I would like to build a simple pedal operated head-switching 'stomp box' to switch two or more SS amps into one 4 ohm cab.

something like this but much simpler:

http://www.tonebone.com/tb-headbone-ss.htm


Could I not just put two 1/4 inputs (from amp) and one output (to cab) with an audio grade switch rated 500w in between and call it a day?

Am I missing something here? The idea is, I just don't want to be farting around with cables on the back of the amp on a dark stage between songs. I would also use this to A/B different amps with one cab etc..

Thoughts anyone?
 
#3
taurus1 said:
I think it would work because they are ss amps and require no load.
Click to expand...

All power amplifier outputs require a load, if it is seeing resistance, regardless of tube vs. solid state. The simple switch method you are seeking might exist in some DIY kit,, or schematic though. It's one thing to not have anything at all hooked up to your amps output, but it is important if you have anything connected to it's output, that it's energy needs someplace to go.


Best advice might be to google some kits or schematics, or just save your lunch money up and buy the real deal.
 
#6
yeah, ss amps don't care, in fact they find open circuits "easier", as they can put their voltage across the terminals without having to create any current to hold it there.

thing is, the switching mechanism would need to handle lots of amp current with no shorts. (it's shorts that are bad for ss, as they try to dump enough current across them to get up to that voltage again, impossible to do.)

i'd be nervous about shorting, arcing and sparking on the switch contacts causing Bad Things to Happen.
 
#8
walterw said:
yeah, ss amps don't care, in fact they find open circuits "easier", as they can put their voltage across the terminals without having to create any current to hold it there.

thing is, the switching mechanism would need to handle lots of amp current with no shorts. (it's shorts that are bad for ss, as they try to dump enough current across them to get up to that voltage again, impossible to do.)

i'd be nervous about shorting, arcing and sparking on the switch contacts causing Bad Things to Happen.
Click to expand...

One way to handle that is to using some sort of timing circuitry so that the input relay mutes the amp input signals just a few milliseconds or so before the output relays change, and hold them muted until a few milliseconds or so after.
 
#9
Yep, the issue here is avoiding the loud "pop" that can occur when switching between the two amps; that pop could be a strong enough spike to possibly damage your speakers. The amps will be fine, and the load is not the issue.
 
#11
How are you going to handle the input switching? If you are going to unplug from one
amp and plug into to the other, then you have manual control over the input.
In that case, a simple DPDT "break before make" switch will handle the speaker.

The commercial units also handle the input switching and timing. But if it's just the speaker
re-cabling that you want to avoid, the right switch will work.
 
#12
megafiddle said:
How are you going to handle the input switching? If you are going to unplug from one
amp and plug into to the other, then you have manual control over the input.
In that case, a simple DPDT "break before make" switch will handle the speaker.

The commercial units also handle the input switching and timing. But if it's just the speaker
re-cabling that you want to avoid, the right switch will work.
Click to expand...

Thats the idea.

Just a foot switch for the speaker cable... manually plug into the other amp before or after etc... possibly with a radial ABY pedal which I already have.
 
#13
bongomania said:
Yep, the issue here is avoiding the loud "pop" that can occur when switching between the two amps; that pop could be a strong enough spike to possibly damage your speakers.
Click to expand...
Actually, it's not. The pop we are all familiar with happens when there is switching on the input of an amp, when that little spike of voltage that occurs when you dump a bit of capacitance onto the input is boosted through the gain stages of the amplifier.
 

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