Trident Series 65/24 Question

Ive got a Trident series 24 console(which has the same input/eq module as the 65),  a lot of free time,  and a need for more headroom.

I've done some heavy digging but can't find much in the way of suggested mods. I've already overhauled the PSU, and implemented the improved grounding scheme. Is there anything else I can do? The only other suggestions I can seem to find is swapping out the op-amps, which the jury seems to be out on, in terms of effectiveness.

Schematic is attached below

I've found the TLE2071 / 72 to be a nice upgrade for the TL071 / 072 (if that's what the board uses). It won't help headroom, but try a couple channels and see if you like it.

For other mods, you could look into modifying the master section.

the big op-amp swamp I have seen  is to remove the tl071/72's and put in opa 134/2134.

As always YMMV

pucho812 said:

the big op-amp swamp I have seen  is to remove the tl071/72's and put in opa 134/2134.

As always YMMV

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Another good choice. The potential issue with those is the larger current draw, power supply may or may not be able to handle it.

pucho812 said:

the big op-amp swamp I have seen  is to remove the tl071/72's and put in opa 134/2134.

As always YMMV

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This is what ive been seeing too. I guess it cant hurt to try a channel and see what I think. Its really too bad the opamps dont come socketed lol :-\

Mostly, my biggest hurdle at this point is the mic pre's break up too soon for my liking. Anything I can do to address that would be huge

john12ax7 said:

Another good choice. The potential issue with those is the larger current draw, power supply may or may not be able to handle it.

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My new power supply is pretty beefy. I would have to double check the numbers, but it should be fine

Um, when you say you need more headroom, where exactly? Pretty sure those boards will do +21 out, normally thats plenty of headroom.

radardoug said:

Um, when you say you need more headroom, where exactly? Pretty sure those boards will do +21 out, normally thats plenty of headroom.

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On the mic pre's, specifically. They break up and distort pretty early on. When im tracking, even with the fader pushed all the way to the top, the signal in my daw is pretty low. I know i can transparently add gain once its recorded, but that  brings up the noise floor, which isnt super useful

I could swear the series 65/24 had sockets.  maybe I am imagining it,  and I put them in last time I serviced one.

pucho812 said:

I could swear the series 65/24 had sockets.  maybe I am imagining it,  and I put them in last time I serviced one.

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Haha, i can say with absolute certainty that at the very least, mine does not . Nothing good comes easy, I suppose

grid_stopper said:

Haha, i can say with absolute certainty that at the very least, mine does not . Nothing good comes easy, I suppose

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well now you can put them in. The easiest way to remove a soldered IC is to cut each leg off the body.  then desolder each pin individually. This is because the IC as a whole  would need more heat for longer periods to get the solder to flow. If you plan on replace the chips, just cut them out, solder in a socket  and then put in the new chip and be done.

I worked at a studio with an SSL 9000 K. all the chips were soldered directly to the PCB. when one would fail, we would remove it and add a socket before putting in a good one. Certain chips were prone to failure.

pucho812 said:

well now you can put them in. The easiest way to remove a soldered IC is to cut each leg off the body.  then desolder each pin individually. This is because the IC as a whole  would need more heat for longer periods to get the solder to flow. If you plan on replace the chips, just cut them out, solder in a socket  and then put in the new chip and be done.

I worked at a studio with an SSL 9000 K. all the chips were soldered directly to the PCB. when one would fail, we would remove it and add a socket before putting in a good one. Certain chips were prone to failure.

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Yeah, that seems like the best way forward. I guess theres no sense in not givinig it a try on a single channel and seeing what happens TL071/2's are cheap if i need to switch back

Not much you can do for the headroom besides isolate where the headroom bottleneck is and rearrange the internal gain structure if it's breaking up.  Is it a known problem on those desks?

Winston O'Boogie said:

Not much you can do for the headroom besides isolate where the headroom bottleneck is and rearrange the internal gain structure if it's breaking up.  Is it a known problem on those desks?

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seems to be a common complaint, but not much available in the way information to address it. The best ive been able to find was something from Jim Williams on an old gearslutz thread where he had this to say:

The 65 mic pre design is a standard 1970's style instrumentation amp, two transistors in front of an opamp without global feedback applied.

Those are also found in early Soundcraft designs. They are rather dirty at higher gains. A better opamp won't do much to fix that. They can be fixed up at the expense of stripping off all the old parts and rebuilding it into a trans-amp with global feedback. Then all those issues go away. Use low noise transistors and you get -129.5 db EIN specs.

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which leaves me with the impression theres not much to be done without a total overhaul

grid_stopper said:

seems to be a common complaint, but not much available in the way information to address it. The best ive been able to find was something from Jim Williams on an old gearslutz thread...

which leaves me with the impression theres not much to be done without a total overhaul

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Yeah I'd say it might unfortunately be the case.  You could always try and adapt an existing mic amp upgrade card into the front end for a few channels, there are some cards for Amek etc that Audio Maintenance in the UK carry.  Or use an SSL pre card or something from somewhere on here? 

Winston O'Boogie said:

Yeah I'd say it might unfortunately be the case.  You could always try and adapt an existing mic amp upgrade card into the front end for a few channels, there are some cards for Amek etc that Audio Maintenance in the UK carry.  Or use an SSL pre card or something from somewhere on here?

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Thats an interesting idea, actually. that being said, the one drawback i see is that the entire channel strip is on a single pcb. I wonder if theres enough room to sneak it on.

With that being said-one of the channels was actually modded to have a Jensen input transformer, AND it is a gain machine. super clean all the way to the top. Theres no documentation as to what they did, but maybe with enough paitence i could reverse engineer it

Op amps on +/- 15 v rails will do +21, so I would suggest if you are having a headroom problem, it is possibly your converters. You need to get a meter or a scope on the problem.

grid_stopper said:

With that being said-one of the channels was actually modded to have a Jensen input transformer, AND it is a gain machine. super clean all the way to the top. Theres no documentation as to what they did, but maybe with enough paitence i could reverse engineer it

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I'd say trace it out regardless of whether you go that route.  It's quite an expensive way to go adding Jensen transformers, but on a channel or two more, if you like what it does.
Also, I bet you could piggy back a little mic pre card onto the channel pcb without too much trouble.  If you like the board except for this bottleneck then it's worth exploring. 
Or send a couple of channels to Jim Williams for whatever is his super-duper upgrade with some feedback around those transistors. 

Otherwise, keep the gain down, faders up, and live with the noise penalty afterwards I suppose.

Your A/D converters could be calibrated for huge levels, perhaps something like +24dBV=0dBFS. You can recalibrate the converters so that +18dBV is full scale and I bet your problems will disappear.

Also, beyond the converter calibration, there is little point in driving the daylights out of a converter. After about +10dBV, most op amp electronics start to distort more noticeably. With converters calibrated to +18dBV = 0dBFS, then you will have 10dB peak headroom at +8 levels, which are still somewhat near the sweet spot for op amp circuits - away from the noise, but away from their "extra distortion" zone.

Another thing to keep in mind is that back in the days of tape, average levels were +4dBu, not +10 to 15dBu. So, running a signal into an 1176 straight to tape for example, the 1176 did not have to push +20-24dBV peak. Some older (classic) gear will not sound right if it has to drive the very last bit of a converter calibrated to +24dBV = 0dBFS. You can run the converter a little quieter, skip modulating all of the available bits, and things will sound better. The price is extra noise, which will always be dominated by your microphone amps at any sane recording levels.

Sounds like an XY Problem to me.

You really need to analyze the noise performance of the system and study the gain structure and understand where you're clipping and why. My guess is that it's actually not the inputs or your noise is high because of another issue entirely.

TL071/2 is a perfectly good op amp. Changing everything to OPA2132 might give you a few dB in noise improvement but it's equally possible that it would actually increase noise because of the increase of current and lack of adequate bypass capacitance.