Fried my receiver...TWICE!

[sevarino]

I have a Sony STR D615 (70 watts per channel main speakers). I just moved into a 5 year old house with in-ceiling speakers. I hooked the received up to these 4 speakers and fried it. I paid $185 to have it fixed (yes...I know...this was stupid). I hooked up the speakers again...and fried it again.
The guy who fixed the receiver said that I must have a short somewhere in the speaker wiring. For the purposes of this question, surround sound is not in play...as these in-ceiling speakers are in different rooms from the TV. Here is the wiring setup: 2 speakers in the bedroom are attached to one volume knob...and 2 speakers in an office are attached to a second volume knob. Both setups are identical, thus I'll only describe the bedroom. The volume knob has 4 inputs and 4 outputs. On the output, a red and black wire goes to one speaker, and a red and black wire goes to the other speaker. On the input, a red, black, green, and white wire goes toward the receiver. As I mentioned, the office wiring is identical to the bedroom. Both 4-wire cables from the volume knob outputs go toward the receiver. These cables are spliced together (red-to-red, black-to-black, green-to-green, white-to-white) with a third 4-wire cable that goes directly to the receiver. I've used a digital multi-meter to test resistance on all connections on the volume knob (outputs and inputs) and found no shorts.
Does anyone know why my receiver has fried twice? Could there be a short somewhere that I am not checking? Is a 70 watt receiver not enough to push these speakers…and could that actually be a reason for a receiver getting fried? Is it possible to fry a receiver by hooking up the speakers incorrectly to the back of the receiver? Of note…I was very careful to make certain that no frayed threads from the speaker wires were cross-touching the other when connecting it to the receiver. Any help / tips would be greatly appreciated before I plug in my new Yamaha 735 watt receiver…I really don’t want to fry this one.

 

[markw]

What are these "volume knobs" to which you refer?

And, yes, you can blow a receiver is the speakers are not hooked up correctly... very easily.

 

[j_garcia]

Even with impedance matching volume controls, the receiver needs to be stable into a low impedance load to provide power to that many speakers at once. Nothing from Sony from that era will come even close to doing this. This setup is most likely intended to be powered by an external amp.

 

[sevarino]

Do you think because the cables from the 2 volume knobs (which were supporting 2 speakers each) were spliced together...that it somehow fried my receiver?

Do you think I should unsplice them and hook them up independently to my new receiver?

 

[TLS Guy]

Do you think because the cables from the 2 volume knobs (which were supporting 2 speakers each) were spliced together...that it somehow fried my receiver?

Do you think I should unsplice them and hook them up independently to my new receiver?

I think you should not use so many speakers. Two probably.

 

[XEagleDriver]

In 2 words - Yes & Yes

Do you think because the cables from the 2 volume knobs (which were supporting 2 speakers each) were spliced together...that it somehow fried my receiver?

Do you think I should unsplice them and hook them up independently to my new receiver?

Sevarino,

From what you describe (spliced wires going into the receiver), the two room's speakers are connected in parallel (L to L and R to R) and thus the receiver is seeing half the speakers original impedance (i.e. assuming 8 ohm speakers, two speakers in parallel result in a 4 ohm load at the receiver).

If I understood your original post correctly, the splice you found is between the two volume controls and the receiver which is negating any impedance match ability the volume control might be capable of (if they have it at all?).

The 615 is not stable down to 4 ohms and this most likely caused the two fries .

Suggested Way Ahead:

Start with learning more about the volume controls you have--consider replacing with ones you know can impedance match if unsure.

Then read Crutchfield's tutorial on multi-room wiring options--pay particular attention to notes about 4-ohm stability and impedance matching:

. . . Link: http://www.crutchfield.com/S-6eMWrenQUC5/learn/learningcenter/home/multiroom_diagrams.html

To Troubleshoot/Fix:
1) I would unsplice the wires, recheck for any shorts, then carefully test only one speaker in only one room starting at a very low volume.

2) If that worked with no issues, connect the other speaker in the same room (to the other set of receiver outputs i.e. L or R) and test it again in the same manner.

3) To connect the other room's speakers DO NOT USE the B speaker connectors! They share only one set of internal amplifiers with the A speakers and will likely fry again given your previous experience!!

Instead, connect the other room speakers to the rear or surround speaker terminals and then use an "all-channel stereo" mode on the new receiver to get stereo sound in both rooms.

4) If the 735 does not have an "all-channel stereo" mode you are probably out of luck in being able to use the 735 for your situation unless you are willing to buy a speaker selector switch (< $50)--that is what I use.

Best of Luck,
XEagleDriver

 

[highfigh]

I have a Sony STR D615 (70 watts per channel main speakers). I just moved into a 5 year old house with in-ceiling speakers. I hooked the received up to these 4 speakers and fried it. I paid $185 to have it fixed (yes...I know...this was stupid). I hooked up the speakers again...and fried it again.
The guy who fixed the receiver said that I must have a short somewhere in the speaker wiring. For the purposes of this question, surround sound is not in play...as these in-ceiling speakers are in different rooms from the TV. Here is the wiring setup: 2 speakers in the bedroom are attached to one volume knob...and 2 speakers in an office are attached to a second volume knob. Both setups are identical, thus I'll only describe the bedroom. The volume knob has 4 inputs and 4 outputs. On the output, a red and black wire goes to one speaker, and a red and black wire goes to the other speaker. On the input, a red, black, green, and white wire goes toward the receiver. As I mentioned, the office wiring is identical to the bedroom. Both 4-wire cables from the volume knob outputs go toward the receiver. These cables are spliced together (red-to-red, black-to-black, green-to-green, white-to-white) with a third 4-wire cable that goes directly to the receiver. I've used a digital multi-meter to test resistance on all connections on the volume knob (outputs and inputs) and found no shorts.
Does anyone know why my receiver has fried twice? Could there be a short somewhere that I am not checking? Is a 70 watt receiver not enough to push these speakers…and could that actually be a reason for a receiver getting fried? Is it possible to fry a receiver by hooking up the speakers incorrectly to the back of the receiver? Of note…I was very careful to make certain that no frayed threads from the speaker wires were cross-touching the other when connecting it to the receiver. Any help / tips would be greatly appreciated before I plug in my new Yamaha 735 watt receiver…I really don’t want to fry this one.

You say you found no shorts but didn't say what the meter showed. 1 Ohm isn't a short but it's way too low for a speaker load.

Just having volume controls doesn't mean you can connect an infinite number of speakers to the terminals on the receiver.