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1974 Les Paul Signature problem?


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Hello all,

 

I have a question concerning a 1974 Les Paul Signature guitar. This is the tobacco burst, hollow body style guitar. I bought this guitar off eBay years ago and decided to get it up and playable 100% if possible. I also posted these questions on the Les Paul forum but I have searched and noticed several people here own one also so I thought I might get some more information.

 

From what I understand, the jack on the front/top is the high impedance conversion and the jack on the side/bottom is the low impedance to connect directly to a board. But when I check the resistance on both I get ~27 ohms. I know the difference between resistance and impedance but with high impedance pickups this is usually close enough to confirm wiring.

 

From the schematic it appears the high impedance output goes through a transformer (which makes sense to me). I would have expected a resistance change due to the extra winding's on the transformer. And being both show this, I noticed either jack has low output as expected from an impedance mismatch into an amp.

 

My questions are:

 

Should I expect a difference in resistance?

 

What should the transformer look like? When I look with a mirror in the cavity I don't see one, but then I am not sure what I am looking for.

 

Any help is appreciated.

 

Thanks,

 

Walter

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Hello Walter and welcome to the Forums.

 

The transformer is the piece mounted on this Recording's pickguard with a metallic ring, and wrapped with black tape:

 

LPR_wiring.JPG

 

It's between the switches on the above picture.

 

Cheers... Bence

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Thanks for answering and the welcome Bence. I guess I should go introduce myself. :)

 

I had a friend back in high school that had a Les Paul Recording, I think it was a model from 1970. Never could get him to sell it to me. :)

 

I went back and looked but still don't see a transformer but I am having trouble moving my mirror around in the f hole (a little too big and clunky, need to find smaller mirror).

 

Is there any chance you have ever measured the resistance at both jacks to tell if there is a difference through the transformer? I just use a guitar cable and measure with an ohmmeter to get an estimate.

 

Hopefully someone that has a Signature will respond to guide me some more.

 

thanks again,

 

Walter

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Does your guitar work? Why are you testing resistance/impedence?

You may be measuring the DC resistance of many components instead of just the jack. Impedance is DC resistance at 0 degs. I never understood impedence. I could calculate it if I had the formula and the values but that wont fix anything.

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Hello Walter!

 

To be honest, I never felt the need to measure anything on my Recording.

 

On the High-Z output it works like a regular guitar - it can be connected to any amp and would work as expected.

 

Through the Low-Z output, it either needs a Shure impedance matching transformer to be connected to regular amps, or can be connected straight to a recording desk. However, my preference is to match the Low-Z output to a normal tube amp via an active preamp circuit.

 

If You are after technical details, I am sure members Daveg and Grog will help You, as they did help me a lot when I bought my Recording.

 

There is a thread dedicated to this topic, in the "Vintage guitars" section of the Forums: http://forum.gibson.com/index.php?/topic/99362-gibson-low-impedance-guitars-club/page__pid__1667320__st__200#entry1667320

 

Best wishes... Bence

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Zentar

 

Well it sort of works. Only it doesn't work with the high impedance output. I have to drive it through a preamp to get any volume. My expectation is I shouldn't have to do that for the high impedance, it should be like a regular (high impedance pickup) guitar.

 

Walter

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Hi Bence,

 

Thanks. Yes, that was what I always expected with the high impedance output. I have to run through a preamp to get any volume and I would not expect to drive it as hard as I did.

 

Maybe one of the others that has one can point me in the right direction if I misunderstood how this works.

 

I will look at that link to see if I can glean something extra.

 

Thanks again,

 

Walter

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