Change the old preamp to a new one

Grisnallen · #1 01-08-2023, 12:53 PM

Hey!
New to this forum. I'm from Sweden but I hope you will understand me anyways!
So, I am about to fix my father's acoustic guitar. An Ibanez AEG8E-BK. This guitar has one xlr and one tele, with the battery socket besides. The output on the preamp is a 6-pin and the input is a 2-pin.
The new preamp that I have bought have the battery socket bult in and a 2,5mm input and a 3,5mm output. The input is no problem to solder the 2-pin to a 2,5mm connector, but how about the output? Since it is 6-pin connector it gets a bit hard. How would you do? Kill the old output and just use the telejack and solder it to a 3,5mm connector? And the old battery socket and xlr stay as decorative?
Hope I made myself understandable 😅

I guess my question is if I somehow can save and use the old telejack and xlr or if I only can save the telejack?

Colin_Mac · #2 01-11-2023, 06:57 PM

I did some reading (https://ibanez.fandom.com/wiki/AEG8E) and the old setup appears to output to a balanced XLR and a stereo jack. Each one of these has three connections, which is why you have six outputs on the preamp.

Your best option is, as you suggest, to leave the XLR and battery socket as decorative, and solder a 3.5mm plug onto the tip and sleeve wires going to the existing jack. The easiest way to identify which wires to use is to plug in a guitar cable to the jack on the guitar and then use a continuity tester to identify which wires are connected to the tip and sleeve of the plug on the far end of the cable.

You should be ok to connect the ring wire (the middle of the three going to the existing jack socket) to the output's ground / 0v.

Grisnallen · #3 01-14-2023, 04:22 AM

Quote:

Originally Posted by Colin_Mac

I did some reading (https://ibanez.fandom.com/wiki/AEG8E) and the old setup appears to output to a balanced XLR and a stereo jack. Each one of these has three connections, which is why you have six outputs on the preamp.

Your best option is, as you suggest, to leave the XLR and battery socket as decorative, and solder a 3.5mm plug onto the tip and sleeve wires going to the existing jack. The easiest way to identify which wires to use is to plug in a guitar cable to the jack on the guitar and then use a continuity tester to identify which wires are connected to the tip and sleeve of the plug on the far end of the cable.

You should be ok to connect the ring wire (the middle of the three going to the existing jack socket) to the output's ground / 0v.

Thanks for the input!
But shouldn't it just be two wires from the stereo jack? As an electric guitar?
I think two of the six wires actually are for the battery. Because there is no more wires than the 2-pin and 6-pin going to the preamp.
I will look in to this later today ��

Grisnallen · #4 01-14-2023, 01:30 PM

Ok, so i soldered the new preamp, and it works. Buuuut I have a bit grounding issues. When I touch the pins in the old xlr jack, or any other metal it goes quite. So it's a grounding issue. Should I shield it somehow? If that's the case, how?
Or have i soldered wrong cables to the jack? It was a white, red and a ground. The ground was easy to spot, the other ones I had to take a chance. But it shouldn't sound anything at all if I've soldered wrong between the red and white, right?

Colin_Mac · #5 01-14-2023, 07:54 PM

My guess is that the stereo jack was originally to carry the same balanced output as the XLR, i.e. a TRS (tip / ring / sleeve) arrangement. So those are the three wires to the jack

When you use a regular guitar lead the plug just has tip & sleeve, and the 'ring' wire on the socket is not used. When the plug is inserted thale ring wire will be shorted to ground so at the inboard side you can leave that wire disconnected or solder it to the ground connection internally.

If you can't see the socket connector inside the body then you need to figure out which wire is tip and which is ring (you already know which is ground). The easiest way, as I said in my original reply, is to plug a guitar cable into the socket and then check which wire connects through to the tip of the plug on the guitar cable (the other end, of course - the end that is not in the socket).

The old XLR jack shouldn't be connected to anything in this arrangement, so touching it shouldn't make any difference to grounding. Did you do anything with the wires from the XLR?

Grisnallen · #6 01-15-2023, 01:55 AM

Quote:

Originally Posted by Colin_Mac

My guess is that the stereo jack was originally to carry the same balanced output as the XLR, i.e. a TRS (tip / ring / sleeve) arrangement. So those are the three wires to the jack

When you use a regular guitar lead the plug just has tip & sleeve, and the 'ring' wire on the socket is not used. When the plug is inserted thale ring wire will be shorted to ground so at the inboard side you can leave that wire disconnected or solder it to the ground connection internally.

If you can't see the socket connector inside the body then you need to figure out which wire is tip and which is ring (you already know which is ground). The easiest way, as I said in my original reply, is to plug a guitar cable into the socket and then check which wire connects through to the tip of the plug on the guitar cable (the other end, of course - the end that is not in the socket).

The old XLR jack shouldn't be connected to anything in this arrangement, so touching it shouldn't make any difference to grounding. Did you do anything with the wires from the XLR?

Thanks for your help!
I have disconnected the cables from the xlr. But there's like a circuit board where both xlr and stereo is connected to. I'll se if I can upload a photo later.

Edit

It seems like the volume is really low too. Don't know if it's because the preamp have a weaker output, or if it's something else ��

Colin_Mac · #7 01-15-2023, 03:41 AM

Whatever that old circuit board is doing, it's not helping. You want the pickup to be wired directly to the preamp input and the output jack to be wired directly to the preamp output, bypassing any parts of the old system that are still in the guitar.

Some photos wouldn help to clear things up.

Grisnallen · #8 01-15-2023, 04:24 AM

Quote:

Originally Posted by Colin_Mac

Whatever that old circuit board is doing, it's not helping. You want the pickup to be wired directly to the preamp input and the output jack to be wired directly to the preamp output, bypassing any parts of the old system that are still in the guitar.

Some photos wouldn help to clear things up.

Alright! I killed the old circuit board and installed a new stereo jack. The problem however seems to be the 2,5mm connector from the pickup. So I have to buy a new one to try.

Grisnallen · #9 01-15-2023, 11:10 AM

A little update. I tried a 2,5mm connector from a charger cable. That did not work. I thought all 2,5mm connectors was built the same, apperently not...
I'll try to find a new one tomorrow.

Grisnallen · #10 01-22-2023, 03:44 AM

I apologize for the triple post.
I soldered a new 2,5mm to the pickup. It's a lot better. I still have some ground issues though. But to be honest I don't know how good the pickup is or in what condition. So it may be a bad pickup, or a bad preamp. The cheapest artec preamp that thomann had. So I think I have to settle.
Thanks for all help!