2. amps-preamps
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Running monoblocks in parallel to increase watts??

Is it possible to run monoblock amps in parallel so as to effectively increase their output wattage to each channel?? I have a set of monoblock amps now that are 100 watts per channel, and want to get a second pair of monoblocks so as to maybe have 200 watts per channel. They are tube monoblock amps, so will this effect impedence values etc??

I know this may take a special interconnect and speaker wire or at least the use of a splitter (or adding another set of output rca's on the preamp) to send the preamp signal to the pairs of amps (2 monoblocks for each channel = 4 monoblocks total) for each respective left and right channel. I assume that the output of the amps will have to "tie" together again (like biwire cable) in the run of speaker wire going from the four amps (2 per channel) to the speaker terminals?

If this possible, would I effectively be achieving 200 watts, or only like 150???

Thanks!

Robert
red2
rwwear
2,692 posts
 
It might work if you can invert the signal to one pair of amps. It would take a fully balanced preamp and you would split the balanced out and send pin 2 plus ground to one RCA on one amp and pin 3 and ground to the other RCA of the other amp. You would have to combine the grounds. You would be effectively turning the amps into fully balanced designs. But, I don't know if this will work with your amps and do not recommend trying it.
elizabeth
6,726 posts
 
Blowing up your amps is what will happen.
Yopur chances of doing what you want without destroying them is like 1 in 10,000.
What you want to do is a no-no for ANY kind of amplifier.
Rwwear does point out a possible way, but to do it successfully, you would have to be an electronics engineering guru. If you were, you wouldn't be asking us!!1
If you really HAVE to have more power, just buy twice as big a pair, and sell you 100 watt babies.
DANGER WILL ROBINSON, DANGER....
drubin
3,240 posts
 
However, if your speakers will accommodate it, you could set up a vertical bi-amp. This won't get you 200 wpc but will get you some of the benefits you are seeking.
jeffreybehr's avatar
jeffreybehr
805 posts
 
Two amazing things--people who don't know how to use SEARCH, and others who know NOTHING of which they speak.

RW, inverting inputs and wiring outputs like that is called bridging. I've never known anyone to try it with tubed amps. PARALLELing channels of tubed amps is an old and effective practice, of which I've written many times. The power simply adds--your 100-Watt channels become a 200-Watt amp--into HALF the indicated impedance. If you used the 8-Ohm taps, you now have 200 Watts into 4 Ohms.

To wire it, use a splitter cable to send the identical signal to both inputs and a short chunk of speakercable to combine in parallel the outputs--positive to positive and neutral to neutral.

I've done this with the 2 channels of c-j MV75s and with EAR monoamps. It's a VERY effective way to drive low-impedance loads with tubed amps.

And before someone writes that the power can't be greater because the Voltage is the same as in one channel, just use the next-higher-impedance taps. But even if there aren't, say, 16-Ohm taps to use, the paralleled taps have half the circuits'/transformers' output impedance, so the damping factor is doubled. Then the paralleled 8-Ohm channels are better able to drive that '8-Ohm' speaker that probably dips significantly below 8 Ohms.

Try it, Red, and you also might try SEARCHing next time. :-)
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