quad eight mic pre [pics]

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its a pain in the ass to get them out but a really secure way to get them in and have them stay there.

remove the four bolts in the transformer. Replace with a bolt about an inch or whatever longer. Drill four holes in your chasis to line up with the holes in the transformer. Slide new longer bolts through the chasis. Put a plastic (you may need to use a metal standoff for the one position with the ground trace) standoff on the bolt, 1/4" will probably do. Now mount the transformer and the pcb back onto the bolts and screw the nuts down on top of the transformer. thats the way I mount all that type of stuff horizontally. Its a bit of a production when you need to remove the amps to fix or swap components but its a great roadworthy solution, once you bolt it down, it aint going nowhere.

dave
 
if I remember right it should make its way to ground somehow. Its been a while since I looked at those. I forgot my picture was sitting at the top of this page, thats how those are mounted in the chasis, like I described.

dave
 
Holy shit! After having this project on the back burner for at least 3 years (if not 4), I finally got all 8 of my Quad Eight cards racked up. I just finished a few minutes ago. Unforunately, I have one bad card, but I think it is the pair of diodes on the rails... should be an easy fix.

Check it out:

quad1.jpg


It's been so long since I started this project, I've misplaced four of the knobs! Hopefully I can find them or I'll have to buy more. D'oh!

The two holes under channels 1 & 2 are for Joe's direct input kits, however the 1/4" jack's threads are not long enough to go through the thick front panel. I'm still figuring out a way around that.

quad2.jpg


Lots 'o iron in this bad boy. It's whisper quiet, too, thanks to putting the power supply (one of Joe's kits, naturally) in a separate case.

quad3.jpg


My wiring is kind of a mess, but hey... it works!

quad4.jpg


Here's the power supply. I'd like to say I came up with the idea of using an old computer PSU case, but I saw it on the web somewhere. I have a million of these damn things lying around and not only do they have a lot of extra wires that can be used for short hook-up runs, but they make a great case for a small power supply. You've already got a mounted IEC jack and a power switch!

I'm headin out of town for a week starting Tuesday so I won't have time to do any real tests, but I'm really anxious to try these on drums! WOO!
 
Yeah! I just started doing the final layout for my QE's too. These were among the first DIY parts I picked up 4 or 5 years ago. I just need to order up a couple of Joe's DI kits, drill the back panel and wire away.
 
Poo-ey... replaced the diodes on the bad card and now it is getting juice but it induces a nasty noise into the entire system and doesn't pass audio. Something is wrong... hopefully bad caps?

The other 7 channels are working great and sound sweet! Miko, Joe has a new go-between kit where you can mount the input transformer directly on the card. I wish he would've had those when I ordered my kits, but again, it took me so long to rack these things up...
 
Well, right now it's a 7 pack because I have one card that isn't working. I hope I can fix it. I've had these cards for years and never tested them until the other night. 7 of them are exactly the same, the 8th one (the one that doesn't work) had different diodes on it and some handwriting on it.
 
Well at least its not the other way 'round!

Seriously, laying out a good one and taking voltage measurements from it should help you find the fault(s) on the bad one, eh?

HTH!
Charlie
 
Ohm out the output and see; doubtful IMO. Also see if you can get a current measurement on the individual module to compare.

I've got a similar 8 banger waiting to build, but with these two channel CA-727 cards. They are same as the earlier AM-3 five transistor CA-127's, but two on a card and no attached output trans. Here's an example of a pair I did FS, with Edcor outputs. I've got just enough of some older Jensen outputs for my keepers. Mine are a fairly rare variation that Ken Hirsch of Orphan Audio / Quad Eight Electronics LLC had to ID for me.

2627879725_66c4815ded_o.jpg
 
I made them. Labels are all old style faux-decal stickers with laquer coating, ala antique WE, military, etc gear.
 

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