Racking Trident Series 80 Modules

Hi all,

I've got a pair of cannibalised S80 Modules I finally start to rack and am wondering if it would be that simple to hook up a transformer for balancing the direct output? Since I'm I don't have a clue which impedance one module would be able to drive I'd really apprechiate any advice. I've already built the PSU and ordered electrolytics - I hope I'll be able to get them up and running in the next weeks...

Thanks in advance,
Christoph

On the 80-series both the Insert Send and the Direct Output Send are driven by a BD517/BD518 pair, so you should be able to just hang an ungapped output transformer on it to get the differential signal with no worries.

The G1176 has this same pair driving its output transformer, so you could just hang a Lundahl 5402 (or Edcor XS1100.... very nice) off one of these outs and you're in business. Actually most any good 1:1 output iron should work well here.

The Insert send takes the signal directly after the eq circuit while the Direct Output Send takes the signal after the fader amp. See which sounds better to you and go for it.

BTW, are you planning to cram those into a 19" package? Are you cutting them up for proper racking or just building a little sidecar-type enclosure for them?

Cheers,

JC

thanks rascalseven,

Many thanks for your recommendation - I'll try a pair of edcors then.

Since the original console where the channels got pulled from is still working, I won't cut them into pieces - a nice wooden box will do the job.

I fired up the first channel esterday and the line input was passing signal. I took the Direct Output Send, since I want to be able to use the eq and attenuate the signal with a pot afterwards. For testing I connected fader top + wiper together with a piece of wire, that should just give me "full" signal, right?.

The thing was acting really weired, no matter if the mic/line switch was depressed, I was always getting signal from the line input. the line gain pot was working fine, but i couldn't get the eq to work. I then desoldered the output cable and touched various places on the board, where I know signal should be (e.g. "EQ IN switch) and the eq was working?! But according to the manual and your post, the signal on the direct o/p shoud be post-everything?

I've got perfect +/-20V supplied, 5V is just for lamps right?

Thanks for your help,
christoph

Do you have the insert send (A28) and the insert return (A11) connected? These must be connected in order for the fader amp to receive the signal from the input and eq section.

If I were doing this I would first hook up stable power and make sure the circuit isn't messing that up... make sure it's stable.

Next take the unbalanced output from the insert send, which should be post eq. Test to make sure this is working. Also, the phase invert amp is just before this output, so check that as well and make sure it's happy.

Then connect the insert send to the insert return with a piece of wire and check the output at the 'fader top.' If all is well there, then connect the fader top to the wiper input and check the direct output (make sure the channel ON switch is 'on').

Going systematically through this order will tell you where any problems exist.

FWIW, the fader top connection is being driven by a TL071, it appears, so don't bother hanging a transformer off of that. Use either the insert send or direct out send for your transformer when you're ready for that.

Peace,

JC

thanks jc,

I have both channels up and running from the line input, psu is stable, even the leds on the mute and eq-in switch are working. I tested the insert send, and also the direct output with sucess. Am missing a 10k log pot, so I connected fader top + wiper directly.

No Signal on the mic in though, when I connect a line level signal it's heavily distorting, but the mic gain pot affects the signal strenght. but that might just be crosstalk on the input section - have to figure that one out. Strangely enough it's behaving exactly the same on both channels. Already changed the chips on the mic section, need to get a scope to trace the signal from the input...

cheers
christoph