TG1 - advice from any one who has built it...

Though it's a small difference when listening at the job with my crappy headphones, the upgraded one feels less congested with the kick and clearer with the rest.

It's better to my ears.

Letting more bottom through.
Holding the snare/room longer.
A touch nicer on the top.

More towards the original type sound imo.

I am having some trouble with this build. Everything seems to work fine except that the unit responds to the hold knob being turned whether there is signal applied or not. The cv test point has between 2 and 5v DC on it depending on where the hold control is set. AC voltage appears when an input signal is applied but the compressor barely responds to it, it does however still respond to the dc. the amp sections work and the AOT trimpots i installed all function as you would expect. when you turn the hold know quickly you can see the attack and release respond and the differnt attack and release position all function correctly. the only thing i cannot get it to do is compress. any help would be great.

StudioSQ said:

I am having some trouble with this build. Everything seems to work fine except that the unit responds to the hold knob being turned whether there is signal applied or not. The cv test point has between 2 and 5v DC on it depending on where the hold control is set. AC voltage appears when an input signal is applied but the compressor barely responds to it, it does however still respond to the dc. the amp sections work and the AOT trimpots i installed all function as you would expect. when you turn the hold know quickly you can see the attack and release respond and the differnt attack and release position all function correctly. the only thing i cannot get it to do is compress. any help would be great.

Click to expand...

this is actually how the tg limiter works! with hold turned up you get maximum 'swing' in gain reduction and as you turn the hold knob down a fixed gain reduction is preset which remains constant. the needle (and the actual gain reduction) has less swing. the whole signal is now of course lower compared to lowering the threshold on a normal compressor, use the output level to compensate. with the hold knob turned down a lot, you need quite a strong signal to see any 'swing' in GR at all.
hope this makes sense, I am finding it quite difficult to explain.... 

ok so, from that description it seems more like an amp with a fader on it. than a compressor. how is it meant to be used then, if it reduces with no signal what is the idea? i am just trying to understand how to use it.

good to know i'm not crazy though, i was messing with this for soooo long.

ok, how to explain. basically just feed it a loud, dynamic signal with hold fully turned up. you should have loads of swing on the needle, the G.R. going up and down according to your time constant settings. Maybe too much? then just turn the hold knob down a little, now the signal will swing between maximum reduction and 'some reduction' but never fully recover back to no G.R. Now turn up the output level until the average signal level is back where you want it. basically it works like a normal compressor, only the "resting" point is not at 0dB but rather at a preset reduction dialled in with the hold knob. you can still achieve "a lot" and "just a little" compression like with any other box, it's just achieved in a bit of a roundabout way. interestingly the compressor will be at its least 'active'  with hold turned all the way down, and loads of static gain reduction applied, but no needle swing and no dynamic G.R.
Can't explain it any better than that. Hope this helps

ok so i had the hold knob backwards because of that. ii get it now, i will give it another shot and see what happens

yeah, ok... it has worked for some time now. I just didn't know how it worked. sounds great.

Regarding the OA202 or 1N4148. My book says OA202 = BA159? The MKII Zener Limiter uses BAY38 which is more or less equal to 1N4148.

Maybe I'm thick or just tired but I'm stumped here.  I'm doing mine in the EMI style with the hold pot.  According to the schematic the signal comes in and goes out for the hold/attack/release through J6 1-6 on the attack recovery board.  So what the heck is IN_POT 1-3 on the Bypass PCB all about?  As far as I can tell I want to jumper 2-3 but is this actually wired to the hold pot also?

Thanks

Nothing to do with the hold pot, just short IN_POT 2 and 3 to bypass input level control.

Thanks!  That's what I thought but I needed that extra bit of confirmation.

Is there any documentation on jumpers JP1 - JP6 on main PCB board , could not locate usage or description
of jumpers here. Used to jumper resistors R48 - R53 on the main board.

Read thru all available build notes , but no info.

There's something under the final test procedure in DESCR.txt:

Testproc:
1). +/-20v
JP1...6, TP+20v, TP-20v

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That's the only place they're mentioned.  From what I gather, I think that means to jumper all the points, then check for +20VDC at "TP+20v", and -20VDC at "TP-20v".  I assume you remove the jumpers after that test.

helpful, I somehow missed it at the bottom of the build docs page. easy to miss.

Did anyone wire TG1 up with the chandler output trafos? What would you recommend/have used for CZ/RZ of the zobel network?

Is anybody else not getting any output?  I'm stymied.  Obviously bypass is fine but when I switch in either the clean or fmrs, nothing.  I am using an SPDT so it's not that.  My meters are dancing so I know I have something coming in.  I've checked, rechecked and triple checked my wiring, it all seems right.  Voltages look good, 20V where it's supposed to be, ground to the tops of my 2N4898 and 2N4910 show 28.3V.  This is happening on both channels, so it must be something I did, twice... I went with 1:1 xfmrs, and the balanced input with the 604.  All appropriate jumpers are in place.  Is there anything I might be missing?

Thanks

are you getting a signal on the unbalanced output of the main board? this is where it connects back to the bypass board.

I'm getting nothing off the unbalanced out.  Also the 2N4910s don't seem to be getting warm at all.  The unbalanced in seems good.  I just rechecked and the positive and negative voltage rails are solid.