[joelongwood]

I'm hoping that someone familiar with the MG Head can explain what's going on with mine. When I plugged my headphones into the amp today, the sound was very strange. Sound was coming out of both channels, but the vocal was very thin, weak and distant sounding with a slight echoey quality to it. I tried different headphones and tubes........same sound. Then I began to jiggle the 1/4 inch plug. The sound became normal for an instant and then reverted to the strange sound. I continued jiggling and the sound changed back and forth, from normal to strange........and then no matter what I did with the plug, the sound remained strange. Then I moved the amp by grabbing the front panel......the sound became normal again. I pulled the bottom of the front panel near the plug away from the chassis and noticed the sound remained normal.........when I pushed it back firmly, the sound became strange again. I really had no desire to open the amp up to see what was going on, so I got out my trusty Swiss Army knife and, as I pried the bottom panel away from the chassis, I wedged a folded matchbook cover in the space I created. The problem is now gone completely. I now realize that when I plugged my 'phones in, I was pressing the front panel in and creating the strange sound situation. But can someone explain what's going on? It's obviously a short of some kind, but if anyone is familiar with the innards of this amp I'd appreciate a more detailed explanation. I'm pretty comfortable with the matchbook fix, but I'd like to know, if I decide to fix it, is it a difficult task to open the amp?

 

[Persiflage]

I encountered something that I think is similar to what you have described with my Cmoy. If either the output or input mini jack is not inserted all of the way, the left and right channels mix, shoving the soundstage right into the center of my head, making the sound weak and slightly echoey.

So maybe pressing the front plate in was causing the the left and right channels to mix? I guess it kinda fits, but I'm a newcomer to all of this audio stuff, so I could be wrong.

I'm not sure if it can happen that way with a 1/4" jack. Anyway I doubt you didn't have them in all the way, but they may be mixing some other way. See if you can experiment with the plug only partially in and see if you can recreate the sound. If you can, then at least you would know what the problem (probably) is.

[edited to make myself less unclear]

 

[joelongwood]

Thanks for the suggestion, Persiflage. I just tried to recreate the sound by a partial insertion of the plug.......couldn't do it. Partially in only gives me sound in one channel. I should menttion that the strange sound I heard was evident on both the 1/4 inch and the 1/8 inch input jacks, so the jack is not defective. Very strange, but as I said, the matchbook seems to have done the trick..............whatever the trick was!

 

[flashbak]

Joelongwood,
Sounds to me like a wire is shorting against another one. It sounds like a very easy fix. All you should have to do is remove the bottom cover to gain access to both jacks as well as the leads going to them. Warning remove the power cord from the wall outlet before attempting the following procedure! With bottom cover removed take the matchbook out and observe what happens when you insert the phone plug and make the necessary correction (probably just some slight bending of the leads away from each other at the jack/jacks). If you don't feel comfortable with this do you know anyone who is handy with electronics? If not, I'll be more than happy to fix it for you for free. All you have to do is get it to me.

 

[joelongwood]

Your explanation and solution sounds plausible, flashbak. And it does eem like a simple enough fix........something even I would be able to handle. I'll definitely make sure to unplug it (it has a removable power cord) before I take the bottom plate off. Thanks for your offer to fix it. If I run into trouble, I just might take you up on it. Geez, 30 years ago I built tubed amps, a pre-amp and a tuner and now I'm worried about taking the bottom plate off this thing. Go figure. Age does strange things.

 

[JMT]

joelongwood

The good news is that once you remove the bottom cover, everything is right there in plain view. The first thing I did when I received my MG Head was to open it up to see what it looked like. It should be a simple diagnosis. Keep us posted.

 

[joelongwood]

Well, I opened it up. Everything is in plain sight, as you said, JMT.
The diagnosis? What this patient needs is a folded matchbook cover wedged inconspicuously between the face plate and the chassis.

I saw absolutely nothing out of the ordinary in there.....bent a few wires further apart.....pressed against face plate and that didn't seem to cause any contact with wires or anything. Plugged phones in......nothing was happening to indicate the problem I had. So I tried it without the matchbook..........strange sounds again! Back went the matchbook........problem fixed to my satisfaction. The strange sound is impossible to recreate with the matchbook in place, no matter how I plug the headphones in, or how I jiggle it. I cut the matchbook down so it's not visible at all. All it seems to be doing is pulling the right hand corner of the face plate away from the chassis, by the thickness of a folded matchbook cover......which is not too damned thick! I think I'll leave well enough alone now, thank you.

 

[joelongwood]

Quote:

The first thing I did when I received my MG Head was to open it up to see what it looked like.

JMT, are you gonna listen to it?

 

[jerikl]

Heh heh, ohhh sweet. I wonder what this thing looks like on the inside...

I think I would probably listen to it first myself... someday I'll get one... but hopefully I'll get a chance to listen to it before that day comes.

Where's that Dallas Headfize meeting?

 

[JMT]

Quote:

JMT, are you gonna listen to it?

Well yes...eventually.

Edit: Right now I am listening to More Music From the Motion Picture Gladiator with the MG Head and my HD600s.
WOW

I now hear why everyone with this combination raves about it. Although I am using the stock tubes that came with it, the Head really makes the 600s sing. I love this full, rich sound. There is a major difference over what I have been hearing through the Creek. I also listened to Patricia Barber - Nightclub, the combination really brings out all of the detail in her voice.

 

[briantf27]

Quote:

Originally posted by jerikl Heh heh, ohhh sweet. I wonder what this thing looks like on the inside... I think I would probably listen to it first myself... someday I'll get one... but hopefully I'll get a chance to listen to it before that day comes. Where's that Dallas Headfize meeting?

It's not a perty thing on the inside...

Brian.