It's a bit ridiculous how much time I've spent trying to research this online and find a product we could use -- but everything is leading to dead ends. However, I think I've figured out a way to quickly switch amps for A/B/C/D amplifier comparison in a manner that cannot affect sound quality. I'd like to get additional input from the forum here to ensure this idea is solid.
I've contacted a lot of companies and people in search for a store bought solution - including Jamo, Klipsch, Part's Express, my work Facilities, avsforum friends and a couple engineers I know and nobody really had any direction on how we could set this up to do fast switching with multiple amps. All of the store bought solutions I've come across only let you switch a pair of amps - and not 4 or 6 amps like we would like to do. I spent about 3 hours at home depot tonight looking at all their hardware trying to figure out a way to make a custom and safe switch board. When I thought I had something that worked I called a couple friends to confirm what they thought. I think MrSmither's and I independently came up with the same solution and tonight when I asked him if he thought it would work he was of the opinion it was the only thing that he could think of that might work as well.
So here it goes.GOALS for G2G!
HOW CAN WE DO THIS?
- Fast amp switching with no setup delays - no time for placebo, emotion, frustration, tiredness, gas pain, or boredom to affect results
- Everybody gets a turn to sit in the sweet spot with their favorite songs and man the switch box to quickly switch through the amp types and hear for themselves if there is a worthwhile difference
- Find/use a switching mechanism that does NOT affect sound quality!
- Utilize the KISS principle - (keep it simple stupid) - no advanced software, hardware, trickery, no stuff to mess up. Let's try to use a physical switching mechanism.
- All amps are will be powered on at all time and will be level matched before the meet.
- The same two speakers will be demoed on each amp in stereo. If interest holds we can swap the speakers out for low sensitivity full range speakers at some point and repeat.
- Each amplifier will be switched at the speaker output side using two double pole single switches. One for the left channel and one for the right channel. Double Pole Single Throw Switches toggle connection with both wires that pass through them - not just a single wire like most typical wall switches.
Here is my kitchen floor mockup
That was pretty crappy and doesn't depict the wiring very well - so here's a visio'esqe diagram.
Notice the switches are organized into pairs. Each pair will control the left and right speaker for one amp. You flip up the left switch and you'll get the left speaker, you flip up the right switch in the pair and you'll get the right speaker. Typically you'd turn on or off each amps switches as a pair (designated by different colored face plates) Turn them both off and then flip the next amp's pair on and you are now auditioning the next amp. Amps can be swapped as fast as you can toggle pairs of switches. A/B/C/D - easy as pie to cycle through. BUT -- turn on two amp's pairs of switches at once by accident - and somethings gonna fry...
So caution and deliberate switch management is critical.
Here are the Double Pole Single Throw switches I picked up at Home Depot. They cost about $6 each x 8. 1/2" Mounting board was $3. 2 gang boxes were $2.25 x 4. Face plates were $1.25 x 4So -- What challenges does this scenario face?
- If two amp switches, IE amp A and amp B switches are both turned on at the same time we are going to fry something or at least throw a amp breaker - NOT COOL! Obviously everything should be off and then each amp flipped on one at time to prevent to amps from loading the same line. Since we aren't powering down the amps - the switches can be flipped as fast as the auditioner wants - just only one switched pair of channels turned on at a time. Hence the reason I got four different colored face plates. If someone wanted to be careful they could engage the left channel of amp A and the right channel of amp B for instance in this setup -- but you'd have to be especially cautious you didn't engage two left channels on accident, and in a group setting it would probably be wise to just engage one amp in full at a time to avoid confusion, mistakes, and heartache.
- We need gads of identical speaker wire - we need to run eight speaker wire pairs from the four amps to the main listening position couch to the switch console. Then those outputs after the switches combined and run a single wire to L speaker and a single wire to R speaker.
- We will be splitting the output signal from the AVR three times using Y splitter -- are we going to lower the output voltage too much from the AVR L/R output for the amps incoming signal? Will we have unwanted amp noise from splitting the signal three times?
I'd like some input and suggestions before I proceed with building this switch box. I bought all the parts already - except the speaker wire - but the parts can be taken back, if this isn't going to work - or someone has a better suggestion. The Roger Russel wire table says we can use 14 gauge wire for up to 40 foot runs to 4ohm and up to 80 foot runs at 8ohm without signal degradation (http://www.roger-russell.com/wire/wire.htm#wiretable
). 40 foot runs should cover the distance from the amp to the couch switch box (20ft) and then from the couch switch box to the front speakers (15foot) in carps room. So really we need to buy about 200 feet of speaker wire to make these ten 20 foot runs happen. But once I start cutting on 200 foot of speaker wire then I can't return it -- so I'm going to commit to this before I proceed much further.