amp problem (1 Viewer)

[Bryan Michael]

i have the onkyo 787 and i went and set it up in 7.1 now the problem is i was using a old recever to drive the rear suround and the amp is shuting it self down i still want to run bith rears and dont have the funds to replace the recever for a amp i was wondering if i ran the out form the single recever to both rear surounds? it gives a power rateing for 8 4 and 3 ohms

 

[Rob Rodier]

It's a good thing I don't have my red marker
I will see if I can understand what you are trying to say. You want to run two speakers off of a a single channel of the older receiver?
I would try to troubleshoot the older unit to figure out what is going wrong. It should have no trouble running a pair of surround speakers.
Two problems with what you might try to do.
1. Running two speakers off of a single channel might get you two seven speakers, but you are still not getting seven different channels.
2. If the receiver is having difficulty driving two speakers on two different channels than it probably will not be able to drive 2 speakers off of one channel. Two speakers is twice the load of a single and the amp needs to work twice as hard to drive them.
Is the receiver well ventilated?
Have you checked for shorts?
I would start there.
-rob

 

[Bryan Michael]

what i was trying to say is that the old recever was running 1 speaker per chanel and it was cutting out i have no shorts and it is in the basement and cold and has alot of space around it and still cuts out. so i decided to run the 2 rear surounds off the 6 the chanel amp of my onkyo and run 2 speakers off it from what i have been told the rears in thx ex is mono

 

[Yogi]

Two speakers is twice the load of a single and the amp needs to work twice as hard to drive them.

I think its true only when the speakers are connected in parallel, halving their impedance so two 8 Ohm speakers connected in parallel act as a 4 Ohm load (tougher for the amp to drive) while two 8 Ohm speakers connected in series act as a 16 Ohm load (easier for the amp to drive). I have never tried connecting speakers in series or parallel to a single output channel on an amp so I dont know its implications on the amp but am speaking from text book knowledge, so pardon me if I am wrong

 

[Rob Rodier]

Yogi, you are correct I had it backwards. Still, there is a problem with the amp that should be addressed. If this works though, go for it.

-rob