Hey, I just got my QSC MX-700 amp and got it hooked up. Very excited I grabbed the remote turned er on and played some music. To my disappointment there was barely any output! I had both chan 1 and 2 gains full and there was barely any bass. I checked all my connections and everything looks correct, I can't figure out whats going! Here's my set-up
Yamaha HTR-5640 subout to:
Behringer FD pro 1124 to:
QSC Mx-700 amp.
I properly bridged the amp by bridging both channels together in the back of the amp and checked the gain level on my receiver and BFD. Whats going on here? Isn't 700 watts supposed to be able to push my Sealed shiva!?!? I'm running out of patience and I'm starting to think I bought a crappy amp off of ebay.
PLEASE someone help me out!
Yamaha HTR-5640 subout to:
Behringer FD pro 1124 to:
QSC Mx-700 amp.
I properly bridged the amp by bridging both channels together in the back of the amp and checked the gain level on my receiver and BFD. Whats going on here? Isn't 700 watts supposed to be able to push my Sealed shiva!?!? I'm running out of patience and I'm starting to think I bought a crappy amp off of ebay.
PLEASE someone help me out!
Are you using the right kind of cables? The manuals should explain how to connect balanced or unbalanced sources.
Some amp brands use non-standard pinouts for XLR. Also, depending on how the balanced line drivers and receivers are implemented, you may need to use different arrangements for unbalanced/balanced adaptor cables. There's a good paper at Rane on cables and stuff.
Another possibility; if the Shiva is DVC (I forget), are the voice coils wired correctly? And is the amp bridged properly?; try running just one channel. Try the amp with a full-range source and see if music comes out. It's like troubleshooting a blocked sewer, you work your way up the pipe looking for presence or absence of "material" and narrow down the problem. Except you don't need to wear gumboots.
Some amp brands use non-standard pinouts for XLR. Also, depending on how the balanced line drivers and receivers are implemented, you may need to use different arrangements for unbalanced/balanced adaptor cables. There's a good paper at Rane on cables and stuff.
Another possibility; if the Shiva is DVC (I forget), are the voice coils wired correctly? And is the amp bridged properly?; try running just one channel. Try the amp with a full-range source and see if music comes out. It's like troubleshooting a blocked sewer, you work your way up the pipe looking for presence or absence of "material" and narrow down the problem. Except you don't need to wear gumboots.
O_ROD,
Did you first try running the amp un-bridged? I run the outputs of my (unbalanced) Sansui AU-X1 direct into a Behringer FBQ3100 EQ and then balanced into a CX-3400 X-over, and back into a pro amp (for bass) and an unbalanced amp (for mids/highs). And have no problems with levels.
I'd suspect hookup.
How was it set up before? You should be able to repeat this with the new amp with no problems.
Did you do the RCA-XLR wires yourself? If so, that could be the problem (the low volume sounds like you're only getting cross-channel talk).
Try one channel only (unbridged) and see what that's like.
Have a good one,
Did you first try running the amp un-bridged? I run the outputs of my (unbalanced) Sansui AU-X1 direct into a Behringer FBQ3100 EQ and then balanced into a CX-3400 X-over, and back into a pro amp (for bass) and an unbalanced amp (for mids/highs). And have no problems with levels.
I'd suspect hookup.
How was it set up before? You should be able to repeat this with the new amp with no problems.
Did you do the RCA-XLR wires yourself? If so, that could be the problem (the low volume sounds like you're only getting cross-channel talk).
Try one channel only (unbridged) and see what that's like.
Have a good one,
I've checked all my connections and everything looks fine. I'm not sure of the differences between unbalanced and balanced, im not sure what I'm using.
The subwoofer is wired in parallell to 4 ohms and is the minimum load for the amp.
I think I may have found the culprit. I don't think the level voltage on the sub out is high enough. I tried turning the volume up and it seemed to get louder, but definitely not 700 watts worth of power. Also, I hit clipping! I think I blew a coil on my sub too
Ugh, this amp is a curse.
The subwoofer is wired in parallell to 4 ohms and is the minimum load for the amp.
I think I may have found the culprit. I don't think the level voltage on the sub out is high enough. I tried turning the volume up and it seemed to get louder, but definitely not 700 watts worth of power. Also, I hit clipping! I think I blew a coil on my sub too
Ugh, this amp is a curse.O_ROD said:
If you dont know how balanced works you can get a lot of strange results.
Explanation of balanced:
http://www.ukslc.org/Technical_Articles/Sound/Balanced_Lines.html
At the bottom of this page you have connectiondiagrams on how to connect balanced and unbalanced:
http://www.rane.com/note110.html
PS: Its an very old but good amp, i installed the bigger MX1500 at a 650people danceclub a couple of months ago and that amp fills the place with heavy bass.
The QSC has a barrier strip and 1/4" connections. If you are going in on the 1/4" then take a jumper and connect pin 1 to 3. You can put this jumper on the barrier strip. If you are using the barrier strip put your hot on the pin 2 and your low on pin 3 and jumper between pin 1 and 3.
I am assumming you are going in unbalanced.
Is there a group of dip switches on the back of the amplifier? Some QSC have these and some require that you flip the bridge dip switches to the bridge position. Have you done this?
What channel are you running the signal into? You need to check the book on this and never assume that it is always going to be channel #1 because sometimes it isn't. What does the book say about which channel control to turn up? This is very important also. I have seen instances when both channels were required to be turned up but this is rare.
Are your speakers terminated to the hots on both channel 1 and channel 2?
Sorry I can't be of more help but I use commercial grade series and this is more suited to light DJ or home usage and I cannot read/see the picture clearly on the QSC page.
Last note*
Never connect the case on a XLR connector to ground. It is not needed and it a left over from the 50's era. All it is good for is ground loops.
I am assumming you are going in unbalanced.
Is there a group of dip switches on the back of the amplifier? Some QSC have these and some require that you flip the bridge dip switches to the bridge position. Have you done this?
What channel are you running the signal into? You need to check the book on this and never assume that it is always going to be channel #1 because sometimes it isn't. What does the book say about which channel control to turn up? This is very important also. I have seen instances when both channels were required to be turned up but this is rare.
Are your speakers terminated to the hots on both channel 1 and channel 2?
Sorry I can't be of more help but I use commercial grade series and this is more suited to light DJ or home usage and I cannot read/see the picture clearly on the QSC page.
Last note*
Never connect the case on a XLR connector to ground. It is not needed and it a left over from the 50's era. All it is good for is ground loops.
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