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Trace Elliot preamp connector


prowla
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I agree that it's for connecting a Trace power amp board.  I tried to read the schematic I found on the web and could see the wiring for the socket but the site was flaky so the diagram didn't stay long enough on my screen to be certain. I'm betting that this unit came from a deceased head as it has no connectivity on the back panel.

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7 hours ago, prowla said:

🙂 Was kindof hoping for something a bit more precise than that!
(For sure it's power, BTW, but may also include signal.)

signal and power

Preamp board, connector circled.

2001346718_Screenshot2023-03-11at20_02_00.thumb.png.935c1bb74a419c9f54581e96ec3e8316.png

 

That would connect to the power amp board here:

1327196748_Screenshot2023-03-11at20_02_14.thumb.png.ff48058691f6a218a8e8bbbb2ca172bd.png

 

 

 

Edited by bartelby
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38 minutes ago, BassmanPaul said:

Connector pin assignment

The pin assigment can vary on TE pre-amp sections. Seeing the front panel might be helpul to identify your version. The schematic applies to MKV GP11's. MK II GP 11's also had extra wiring for the ECI function ( earth continuity indicator ).The MKV GP11's were used on a multitude of different amps but mostly AH150 heads and AH250 heads. Both had different feed voltages from the power section tranformers. Basically they use a half wave rail voltage from the main power supply, a big step down resistor on the pre-amp main board, a voltage regulator and zener diode run the pre-amp on roughly 30-35V dc. On my AH250 the feed voltage to the GP11 MK V via the 6 pin connector is 65V dc. On my AH150 GP11 MKII it is actually higher at 71V but thats because it has a rare 50V transformer and not the usual 40V one. The step down resistors are the critical part as they drop enough voltage so as not the smoke the pre-amp🥵 Some of these pre-amp sections aren't really interchageable between different models even though they have the same 6 pin multi plug socket. Might or might not work and you might or might not get smoke!

I've just rebuilt one recently ( a MKV GP11) that had been through the wars. The multi plug was missing, long gone on a dodgy amp service years ago and the cables were hard soldered onto the pins. See pic, the red and black are the power supply, the blue  is tip/signal out and the signal out screen is on pin 6. 

241847706_Screenshot2023-03-11at22_29_02.thumb.png.f174fc2397489856dc97e43d97eccac6.png

A 2 core screen cable out to a power amp and a pos and neg from a supply voltage ( anything around 60v dc would likely do) and would most likely get your pre-amp working assuming its in good order. 

Edited by DGBass
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A simple power supply is not a major problem - it has a fuse, transformer, bridge rectifier and two smoothing capacitors. Your cheapest option to avoid paying out for an amplifier-rated transformer would be to buy two smaller 18-0-18 transformers and wire the outputs to give 36-0-36. That's still £40+ just to see if it works...

 

Connecting to the board would be neater with the right plug, although you could just bypass the plug as in the photo - you could hard-wire it, or use an XLR for power and jack for signal.

 

I'm wondering if the plug is a Molex - they were common at the time, but some were limited to 12v max. They are still used on PC power supplies to disc drives.

David

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So, it may be a Molex connector, like in a PC, or something similar which is rated at a higher voltage.

 

and the pins are:

  1. Ground (power and signal)

  2. +ve rail, which may be 30V, 36V, or perhaps 71V, current unsure.

  3. Signal.

  4. -ve rail, as per +ve.

  5. n/a

  6. n/a

 

I'm pretty sure it's originally from a head or combo, but the power supply/amp stage has presumably shuffled off this mortal coil and so the question is whether it can be converted to a standalone preamp and whether it is worth the effort.

The background is I've been looking at buying it, probably for £50, but I think I'm going to pass, as it'll just be another project for me (I seem to collect projects!).

If anybody's interested, it's on FB Marketplace: https://www.facebook.com/marketplace/item/564451868674188/

 

 

 

 

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It's an earlier MKII GP11 in the FB ad so above schematics wouldn't apply. These also have the ECI wiring which is a heap of trouble if you can't test its working before buying it. It will likely have come from an early AH150 or AH250. The ad picture looks like a rather poor condition and well used unit with missing knob caps and a non standard input jack. So its had work before and i would guess would need a fair bit of work to bring it up to standard. You could easily spend another £50 getting it working and at the end of the day you would struggle to ever recoup that. £25 spares/repairs is probably more realistic unless the seller has the old blown power amp unit he could throw in. The power amps are generally bullet proof and very easy to fix if they do stop working. The pre-amps are a bit more complicated.

The trouble with starting a project like this these days is that folks are stripping down old trace amps because they realise they can make a lot more money selling parts than a whole unit for spares or repair. Parts are sold as no return/untested so if you do by a dud part theres little comeback. Whole working TE amps of this era in good nick and reasonably original condition are becoming very scarce nowadays and that will probably encourage the parts strippers to break up anthing they can get their hands on. 

Saying that, its a good enthusiast project and with a bit of work, a suitable power supply and a nice slim 2U rack case it would make a great wee project and a brilliant pre-amp once working. These old GP11 pre-amps have a great silky smooth tone. I can vouch for that as I have one in perfect working order and very good original condition 😁

IMG_1888.thumb.jpeg.4c2bbca9bb63f73325275093cc105c9c.jpeg

 

 

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