Firstly, I apologise if this is a dumb question...I'm new at this. I bought a used amp to power my home theater subwoofers as the previous plate amp wasn't quite gutsy enough. I connected my sherwood RD6505 home theatre amp to my 4 x 12" rockford fosgate subs via the new AM XA1400 amp. Amp came on, no sound came out. As far as I know, all connections and settings for bridged operation are correct. Question is, is the lack of sound due to the difference in output/input ( 1K ohm and 1V from home theatre into 20K ohm and unknown voltage of amp), using unbalanced RCA to balanced XLR adapters, or is there another incompatability between home stuff and pro stuff I'm unaware of.
Whatever is going on will not be down to the 1v/1k into 20k/unknown sensitivity of the amp.
All that means is the 1k is an output impedance that gets loaded by 20k of the following amp. So a little (very very little) attenuation occurs. So its not that.
Balanced connections... worth looking at what you are actually feeding into them. Balanced means in essence that as one side goes up the other goes down in voltage. So if by chance your lead applied the same single feed to both sides of the balanced input then the net result would be no audio as there would be no difference in voltage between the two sides.
First quick check would be to just try another source in place of the Sherwood just in case there was no output from that.
Then check your unbalanced to balanced adapter setup.
All that means is the 1k is an output impedance that gets loaded by 20k of the following amp. So a little (very very little) attenuation occurs. So its not that.
Balanced connections... worth looking at what you are actually feeding into them. Balanced means in essence that as one side goes up the other goes down in voltage. So if by chance your lead applied the same single feed to both sides of the balanced input then the net result would be no audio as there would be no difference in voltage between the two sides.
First quick check would be to just try another source in place of the Sherwood just in case there was no output from that.
Then check your unbalanced to balanced adapter setup.
I unplugged straight from the old sub amp to the new one, so I'm pretty sure there's a signal. The adapters are meant to be wired from the centre pin of the RCA to pin 2 of the XLR. It didnt occur to me one may be wired to pin 1 cancelling each other out....I'll open them up and check. Thanks.
I just found this in the amps manual ....
" In-line XLR connectors often have a termination lug that connects directly to the chassis of the connector.
IMPORTANT: Do not link this lug to pin 1 at the amplifier’s input as it
will defeat the amplifier’s input grounding scheme. "
This how mine are wired. I'll try rewiring the adapter and post the result.
" In-line XLR connectors often have a termination lug that connects directly to the chassis of the connector.
IMPORTANT: Do not link this lug to pin 1 at the amplifier’s input as it
will defeat the amplifier’s input grounding scheme. "
This how mine are wired. I'll try rewiring the adapter and post the result.
One of those things you would have to actually see I suspect... to see just what how it is configured.
If you apply conventional single ended (unbalanced) audio to just one side of the balanced XLR input then you should get audio. The unused side would probably need to be grounded to prevent stray pickup.
This is the sort of thing. The normal RCA audio feed needs to go to pin 2 or pin 3 (either will work but one side will give a 180 degree phase reversal) and the RCA ground goes to pin 1.
If you apply conventional single ended (unbalanced) audio to just one side of the balanced XLR input then you should get audio. The unused side would probably need to be grounded to prevent stray pickup.
This is the sort of thing. The normal RCA audio feed needs to go to pin 2 or pin 3 (either will work but one side will give a 180 degree phase reversal) and the RCA ground goes to pin 1.
Attachments
Have you looked at the owners manual to verify you have everything connected and set correctly?
Home theater receivers generally don't generate a very strong signal on their preamp outputs while pro amps generally require a pretty high input voltage, and that often results in little or no sound. But this amp has a selectable input sensitivity where the -6 setting would be closest to the -10dbu standard for home audio.
You have 4 subs connected to this amp in bridge mode? What impedance are the subs and how are they connected together? I suspect it would take a series/parallel wiring to achieve the 4ohm minimum rating the amp has in Bridged mode.. given 4ohm subs.
Home theater receivers generally don't generate a very strong signal on their preamp outputs while pro amps generally require a pretty high input voltage, and that often results in little or no sound. But this amp has a selectable input sensitivity where the -6 setting would be closest to the -10dbu standard for home audio.
You have 4 subs connected to this amp in bridge mode? What impedance are the subs and how are they connected together? I suspect it would take a series/parallel wiring to achieve the 4ohm minimum rating the amp has in Bridged mode.. given 4ohm subs.
Thanks Mooly, I've rewired the adapters so the sleeve is no longer connected to ground. Haven't tried it yet, but fingers crossed it will work.
And thanks conanski, the voltage output of the preamp is the only parameter I can't find. I have the amp input set to -6dB as you suggested assuming that would help with the wussy output of the preamp. The 4ohm subs are wired as two parallel series of two, so as far as I know the amp will see this as 1 4ohm speaker.
And thanks conanski, the voltage output of the preamp is the only parameter I can't find. I have the amp input set to -6dB as you suggested assuming that would help with the wussy output of the preamp. The 4ohm subs are wired as two parallel series of two, so as far as I know the amp will see this as 1 4ohm speaker.
Well....sorry I took so long, but even though the adapters are wired with the centre rca pin wired to pin 2, and the sleeve wired to the other 2 pins ( leaving the xlr sleeve unwired ) there is still no output from the amp. I'm officially confused. My only other thought is that the circuit breaker switch seems a bit wobbly. Is it possible that it has been tripped, if so, how do I reset it ? ( pressing it does nothing ). Any input would be appreciated.
As I mentioned earlier, this is probably one of those items and setups that you need in front of you to really suss out and see what is going on.
I can't see how anything related to fiddling around with an input would cause the amp to go into protection. Things like a DC voltage being present on the applied inputs would probably do it. I can't think of much else really for that 🙁
I can't see how anything related to fiddling around with an input would cause the amp to go into protection. Things like a DC voltage being present on the applied inputs would probably do it. I can't think of much else really for that 🙁
That sounds like a permanent 'hard' fault then rather than an applied signal/voltage causing it to temporarily go into protect 🙁
Thanks Mooly. Sounds like I bought a dud. With any luck I can get a refund through the auction site I purchased it through as they advertised it " ïn working order ".
that sounds like a plan. Good luck