View Full Version : Main in/pre out jumpers on receiver


soundweasel
06-11-2007, 08:23 PM
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?

Whitehall
06-11-2007, 08:27 PM
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.

soundweasel
06-11-2007, 08:36 PM
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
06-11-2007, 09:28 PM
My Marantz 4300 and many others require the jumpers.

To do what?! I just put a pair on one of the receivers that didn't have them. What's the difference?

rickr15
06-11-2007, 09:49 PM
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.

KingBubba
06-11-2007, 10:00 PM
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.

LBPete
06-11-2007, 10:00 PM
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

Rex Everything
06-11-2007, 10:01 PM
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.

Whitehall
06-11-2007, 10:56 PM
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.

Lefty
06-11-2007, 11:35 PM
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

dougp
06-12-2007, 08:34 AM
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.

bully
06-12-2007, 08:44 AM
What doug said--i would want a receiver/integrated amp with pre out/main in just on principle.

rickr15
06-12-2007, 08:56 AM
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.

Sluggo
06-12-2007, 11:03 AM
I have Scored quite a few units,described as
"It Powers up,but It doesnt make any sound"
Because there were no jumpers in place.

KingBubba
06-12-2007, 03:29 PM
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.

Cosmic Charlie
06-14-2007, 12:37 PM
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

Joewp
02-11-2011, 11:07 PM
I have a Marantz 2235B, but it does not have the jumpers, should it? And if so, where can I get replacements?

amason3
02-12-2011, 01:22 AM
I have a Marantz 2235B, but it does not have the jumpers, should it? And if so, where can I get replacements?

If it's working then no. If it has internal jumpers and they're corroded or broken, then yes.

Joewp
02-12-2011, 08:11 AM
Yep, works fine, thanks!

maddog37
01-14-2012, 10:31 PM
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.

Hwy61
02-06-2012, 01:01 PM
I have a Marantz 2238b Receiver.... recently picked up a nice Marantz 170DC amp... the thought to use the 2238b as a pre amp for the 170dc came to mind and to my surprise when I checked the back of my 2238b I noticed there are no jumpers in place.... but the 2238b has always worked just fine.... makes no sense really ...

So, now I want to use the 2238b as a pre amp for the 170dc... I connect RCA cables from pre-out on the 2238b to "input" on my 170dc and that should bypass the internal amplifier on the 2238b in favor of the 170dc ? Correct ??

I suppose I will do that at least until I can find a nice Marantz 3250 or similar pre amp ....I have a same era Marantz tuner already....

J English
02-17-2012, 10:00 AM
I'm curious, has anyone tested an upgrade from 'standard' wire jumpers to special jumpers? I am looking at a couple of Auricle Audio Design products on eBay. They make "Reference Jax" jumpers for about $30 and "Jumpin Jax" jumpers for about $60. Does anyone feel that better jumpers can improve the sound on standard vintage receivers (HK, Yamaha, etc.)?

62caddy
02-17-2012, 10:09 AM
My McIntosh receiver has pre-out/main in jacks but does not require traditional jumpers- the connections are made internally. This enables additional amp(s) to be fed by the receiver's preamp without losing the signal feed to the receiver's main amp. Only by connecting RCA jacks to the MAIN amp IN will the preamp signal be cut to the receiver's main amp.

I believe it's recommended to insert shorting plugs at the MAIN IN of the receiver if its power amplifier is not needed.

taskerc
02-17-2012, 06:51 PM
I'm curious, has anyone tested an upgrade from 'standard' wire jumpers to special jumpers? I am looking at a couple of Auricle Audio Design products on eBay. They make "Reference Jax" jumpers for about $30 and "Jumpin Jax" jumpers for about $60. Does anyone feel that better jumpers can improve the sound on standard vintage receivers (HK, Yamaha, etc.)?

Most NAD amps/receivers hae the single metal conductor jumpers and fans have always said these need to be replaced with "real"cables.

Idid this on one of ine and it did seem to improve the receiver -that one was a 3130 receiver.

sKiZo
02-17-2012, 07:54 PM
Done right, a true pre out/amp in loop is a cleaner signal path. Most tape loops alter the signal which can annoy some amps looking for a pure line input.

Another benefit is that the pre out/amp in allows you to control your outboard amp directly from the receiver. Any controls built into your receiver - volume, tone, filters, etc. will also control the outboard amp. Just set your amp volume once to just below "omg we're all gonna die" and leave it there.

J English
02-17-2012, 08:01 PM
Most NAD amps/receivers hae the single metal conductor jumpers and fans have always said these need to be replaced with "real"cables.

Idid this on one of ine and it did seem to improve the receiver -that one was a 3130 receiver.

Are the NAD ones worse than the ones that are on Yamaha, HK, etc.? The eBay listing for these does directly reference NAD, which confused me.

taskerc
02-17-2012, 08:03 PM
The NAD ones are basically a rounded piece of what looks like aluminium wire. I have had a few NAD devices and they have all been the same, except one which was a nice shiny steel wire piece - that is my current 7140 receiver.