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[kfowler8]

I've got an issue with the balanced line input in the rear of my MP-1. When I use that jack, it's almost as if the signal bypasses the preamp. Like if I'm on a dirty channel, the sound is clean. If I swap the line to the front input, it works fine. I've tried using both balanced (TRS) and unbalanced 1/4" jacks but I get the same sound every time. (For the balance line, I'm running from my wireless which has a balanced XLR out and then to a TRS plug.)

I'm not sure if someone screwed with the rear jack trying to make it unbalanced or what. Any ideas?

[GuitarBuilder]

AFAIK there's no balanced line input on the rear of an MP-1.

[MarshallJMP]

Well the V1.xx do have a balanced line in.Maybe your wireless doesn't have enough output to drive the line in.What wireless do you use?

[kfowler8]

Well the V1.xx do have a balanced line in.Maybe your wireless doesn't have enough output to drive the line in.What wireless do you use?

Yes it's a V1.xx. The wireless is an older Audio Technica. I can't remember the model number but it's one of the nicer ones. It was like $600 back in the day. Works really well. I'm probably going to end up just doing the mod to convert to an unbalanced input. Still curious as to why it's not working right.

[MarshallJMP]

If you let me know the exact  model i can look up the specs.

[kfowler8]

If you let me know the exact  model i can look up the specs.

Pretty sure this is it. Let me know what you think. Thanks!

http://www.audio-technica.com/cms/wls_systems/bc4c313cbad539d8/index.html

[rnolan]

MJMP was on the money, it does 100 mV unbalanced and 31.6 mV balanced, so the balanced out is less than a third of unbalanced and the rear MP1 input probably wants ~1V ish (1000 mV).  These units were made for wireless mics (from what the link shows) and thus designed to plug into a mixing desk mic input (thus balanced option but low/mic level so not to overload it).  So use the unbalanced out (the cable is short, balanced doesn't add much (if any IMHO) value).  To use rear input, do the mod (looks pretty easy IIRC), or use front input 

[kfowler8]

MJMP was on the money, it does 100 mV unbalanced and 31.6 mV balanced, so the balanced out is less than a third of unbalanced and the rear MP1 input probably wants ~1V ish (1000 mV).  These units were made for wireless mics (from what the link shows) and thus designed to plug into a mixing desk mic input (thus balanced option but low/mic level so not to overload it).  So use the unbalanced out (the cable is short, balanced doesn't add much (if any IMHO) value).  To use rear input, do the mod (looks pretty easy IIRC), or use front input 

OK, got ya. Looks like I'll be doing the mod then.

[kfowler8]

Thinking more about this, it's kind of like turning my vol pot on the guitar to almost zero hence why it cleans up. I wonder what in the world the balanced input was supposed to be for?

[MarshallJMP]

Even 100mV is low,usually pickups put out alot more,depending what type between 500 and 1000 mV.But i saw there is a trimmer on the transmittor so maybe you can get a hotter output,and there's also a volume pot on the reciever,best is to crank it (it's also in the manual).

Did you try it in the front input?does it work well there?

[kfowler8]

Yeah front input works fine. I'll check the trims and see if I can boost it.

[rnolan]

I wonder what in the world the balanced input was supposed to be for?

Good question, apart from being able to have really long leads, low impedance ~600 ohm (i.e. >25 feet when unbalanced high impedance looses top end) on a big stage.  I don't know anyone who has ever used it, I've come up with some zany patch ideas that incorporated it but never tried them.  Jur and I talked about it a bit, not sure he ever tried though, but that was in the context of using it MP1 as a desk insert on his vocalist's mic channel

[MarshallJMP]

I think the line in was for reamping.

[El Chiguete]

reamping in the 80s???

[rnolan]

Reamping isn't new idea, been around for ages, just not that common maybe ?