Main in/pre out jumpers on receiver

soundweasel

Super Member
Some of my Marantz receivers have Main in/Pre out jumpers plugged in. Others don't. All work OK with my DVD player plugged into the aux input. Why do you need Main in/Pre out jumpers on a receiver?

On my Kenwood integrated amp the Main in/Pre out jumpers need to be in place in order to get any sound out of it.

Not the case with the Marantz receivers.

What am I missing?! :scratch2:

BTW -- does anyone have a copy of a manual for a Marantz 2330?
 
My Marantz 4300 and many others require the jumpers. Some brands like Yamaha have internal jumpers so work without the external connections.

My Sonys don't have anyway to separate the pre and main amps.
 
According to my 2230 manual: "Removing these two special jumper plugs allows you to use your 2230 an an independent basic stereo amplifier and/or an independent stereo control center. Be sure to replace the jumper plugs between the MIN IN and PRE OUT jacks for normal operation."

The receiver(s) without the jumpers have been operating in a "normal" fashion for quite some time now?!?!
 
soundweasel said:
To do what?! I just put a pair on one of the receivers that didn't have them. What's the difference?

Maybe Marantz is different but if I pull the jumpers on any of my amps or receivers I lose all sound.
I think at the time most used the pre in/main out as a place to insert a graphic equalizer or other signal altering devices into the signal path.
 
An EQ or processor loop was one of the uses for the in/out. It also allows you to control more than one amp with the one preamp. Also if either the preamp or the amp should die you can always still use the remaining working component with another amp or preamp. I prefer to have an in/out, but as pointed out, not all units have them. The units that work without a jumper in place will have a switch on he back that acts as the jumper.
 
I believe some of the Marantz models had internal contacts in the preout RCA Jacks. If nothing was plugged into them, the contacts would close and pass the signal internally from the pre out to the main in. If you plugged in an RCA connector, the contacts open seperating the pre out and main in. I don't know for sure which models do this.

- Pete
 
Some of the Marantz units have internal jumpers and some of them have the jumpers that need to be inserted in the rear.

The jumpers connect the power amp section of the receiver and the preamp section of the receiver. If you disconnect them then you can use the preamp section with a different amp and the power amp section with a different pre if you like.
 
I picked up a nice Marantz integrated that had a bum pre-amp. It was VERY cheap. I pulled the jumpers and used it as a power amp.

You can also take the pre out, connect to a crossover and feed one level back to the amp and the other(s) to other power amps.

Having a jumper can be a real convenience.
 
LBPete said:
I believe some of the Marantz models had internal contacts in the preout RCA Jacks. If nothing was plugged into them, the contacts would close and pass the signal internally from the pre out to the main in. If you plugged in an RCA connector, the contacts open seperating the pre out and main in. I don't know for sure which models do this.

- Pete

You are correct. One model, the 2325 had those internal switched RCA jacks as I owned one for a while. Not sure what other Marantz models had them, certainly not all of them, so it can get confusing even for the more experanced collectors.

Not sure if any other manufacture used internal switched RCA connectors, all though many used a slide switch to do the same function there for not requiring the short jumpers....

Lefty
 
Rex Everything said:
The jumpers connect the power amp section of the receiver and the preamp section of the receiver. If you disconnect them then you can use the preamp section with a different amp and the power amp section with a different pre if you like.

That's what I am going to do. I bought a new amp. Until I find the preamp that I want, I will just run the amp off the pre-outs on my receiver. It's a very useful feature. For me, its often a sign of quality. I tend to avoid receivers without a preout.
 
They can be very handy. I have a Yamaha A-1000 HT amp that sounds like muddy crap no matter what setting you have it on. Pull the jumpers and use a dedicated 2 channel pre amp and it becomes one of my favorite sounding amps.
 
I recently bought a Kenwood KR-8050 off the bay and from the lousy picture it looked like it had out/in plugs with no jumpers. When I got it I was disappointed to find I was mistaken. I would expect that a receiver of that size and caliber to always have them but I guess not. They are a big plus in my eyes.
 
I've found, with my Pioneer SA9500 that somehow the amp sounds louder with the jumpers installed and the internal switch in the disconnect position. I've experimented and found this to be true. CC
 
I have a Marantz 2235B, but it does not have the jumpers, should it? And if so, where can I get replacements?
 
That's an interesting situation. I have a Marantz 2230 that I thought had a problem when I bought it, read the owner's manual and all worked fine once I plugged in RCA cables.

Somewhere I read that the main in/pre out jumpers only apply to 2230 and larger receivers, but are internal on smaller units. I'm now using the 2230 as a preamp, and it sounds pretty damn good.
 
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