Parallel amps wiring

[martin155]

Can I wire 2 amps in parallel (according to schematics in the attachment) and if so will be output impedance of amps changed after that e.g. for two 8 Ohms speakers?

 

[rayma]

Can I wire 2 amps in parallel

No, don't attempt this, or amplifier (and maybe speaker) damage will result.

 

[martin155]

OK and is it possible to use 2 channel amp as monoblock for 1 speaker?

 

[rayma]

That's possible in the bridge mode, if it's available. Which amplifiers do you have?

 

[martin155]

TU-8200. If the bridge mode is not available is there some other way?

 

[rayma]

If you build an outboard unity gain inverter stage, you can feed balanced signals to the two amp inputs, and connect one speaker between the two "hot" 8 ohm outputs. This makes the stereo amp into a monoblock.

But this would only work well enough with a 16 ohm speaker. These amps have just 8 ohm and 4 ohm outputs, but not the 16 ohm taps that would be used for bridging with a typical 8 ohm speaker.

 

[martin155]

If you build an outboard unity gain inverter stage, you can feed balanced signals to the two amp inputs, and connect one speaker between the two "hot" 8 ohm outputs. This makes the stereo amp into a monoblock.

But this would only work well enough with a 16 ohm speaker. These amps have just 8 ohm and 4 ohm outputs, but not the 16 ohm taps that would be used for bridging with a typical 8 ohm speaker.

I thought when bridging the amplifiers the load impedance would be halved so if I have 8 ohm speakers I would set output impedance on amplifiers on 4 ohm. I probably don't understand correctly.

 

[rayma]

I thought when bridging the amplifiers the load impedance would be halved.

It actually doubles, since the channels are in series, and out of phase.

 

[martin155]

So it skould be ok to use 4 ohm speakers then I will have 8 ohm on amps outputs in bridge mode right?

 

[kodabmx]

I've paralleled amplifiers BUT: I built them myself. They were identical. They used sweep tubes, and beefy power toroids as OPTs. I really liked the sound of it, but then I built a single amp that was more powerful and called it a day.

 

[rayma]

So it skould be ok to use 4 ohm speakers then I will
have 8 ohm on amps outputs in bridge mode right?

No, just the reverse. In the bridge mode, you would connect either:

one 16 ohm speaker between the two 8 ohm taps

or

one 8 ohm speaker between the two 4 ohm taps