Recapping a trident series 75/65 input module questions?

[Trench Studio]

Hello All. I'm new here, I have had my series 75 console (28/24/2) for about 13 years and I am just now looking to recap and change some OP AMP IC chips in certain areas on each strip.

1.) My question is do I keep the same radial cap values as the originals? 
I had 4 channels upgraded by Jim Williams and the caps were beefed up while using Wima Film Capacitors on backside of module I'm assuming to compensate for the increase? My questions is should I keep it stock values or beef them up? It's more cost effective to keep stock values. I do like the sound of the upgrade but I was hoping to achieve an overall better sound on the unmodded channels by just recapping and by changing the IC's in certain areas (preamp, line input, and fader).

2.) Should I change all the Film Caps as well? I don't know the values I need for those as they are not clearly marked on the existing ones. I see the ones used on the upgraded modules can I use those values? I'm not sure if I will need to change the resistors or not in those areas.

I am new to all of this but not afraid to get my hands dirty and have a few channels not in use to learn on.  :-\

I have yet to build a new power supply, thats next on my list... any advice (amperage or configurations) for a supply would be greatly appreciated. I am aware of the Acopian builds and some prebuilt ones I've seen on ebay.

Thanks in advance for any help.

 

[pucho812]

IF you like what Jim williams did then why not just copy it so it's all uniform?

 

[JohnRoberts]

Hello All. I'm new here, I have had my series 75 console (28/24/2) for about 13 years and I am just now looking to recap and change some OP AMP IC chips in certain areas on each strip.

1.) My question is do I keep the same radial cap values as the originals? 
I had 4 channels upgraded by Jim Williams and the caps were beefed up while using Wima Film Capacitors on backside of module I'm assuming to compensate for the increase? My questions is should I keep it stock values or beef them up? It's more cost effective to keep stock values. I do like the sound of the upgrade but I was hoping to achieve an overall better sound on the unmodded channels by just recapping and by changing the IC's in certain areas (preamp, line input, and fader).

The nice thing about recording consoles is how easy it is to do side by side comparisons of modified and unmodified channels. Further you can perform null tests to objectively determine the amount of difference.

I am not a fan of second guessing design engineers, but Jim has been doing that for years with good results.

My advice would be to first benchmark the unmodified channels. A rigorous frequency response test can help identify any tired electrolytic caps. So first step is to quantify the current state of the unmodified strips. Then compare the William's strip to a good stock strip (I would expect somewhat extended frequency response to dominate the null product).

I would suggest freshening up a strip with stock values and see how that sounds.

2.) Should I change all the Film Caps as well? I don't know the values I need for those as they are not clearly marked on the existing ones. I see the ones used on the upgraded modules can I use those values? I'm not sure if I will need to change the resistors or not in those areas.

Film caps are generally more reliable than electrolytic and more linear so there should be less room for improvement from replacing them.  Again you can answer the question yourself by modifying a channel and seeing what difference it makes.

I am new to all of this but not afraid to get my hands dirty and have a few channels not in use to learn on.  :-\

I have yet to build a new power supply, thats next on my list... any advice (amperage or configurations) for a supply would be greatly appreciated. I am aware of the Acopian builds and some prebuilt ones I've seen on ebay.

Thanks in advance for any help.

Good luck... perhaps search the forum for other similar projects.

JR

 

[Trench Studio]

IF you like what Jim williams did then why not just copy it so it's all uniform?

I wouldn't necessarily mind doing just that but my concern is the newer looking resistors that may have been swapped in for different values. I'm also curious about the sound of different opamp choices. Maybe I will try and call Jim and see why he did what he did to better understand the need for the beefed up cap values and additional film caps.

The nice thing about recording consoles is how easy it is to do side by side comparisons of modified and unmodified channels. Further you can perform null tests to objectively determine the amount of difference.

I am not a fan of second guessing design engineers, but Jim has been doing that for years with good results.

My advice would be to first benchmark the unmodified channels. A rigorous frequency response test can help identify any tired electrolytic caps. So first step is to quantify the current state of the unmodified strips. Then compare the William's strip to a good stock strip (I would expect somewhat extended frequency response to dominate the null product).

I would suggest freshening up a strip with stock values and see how that sounds.

2.) Should I change all the Film Caps as well? I don't know the values I need for those as they are not clearly marked on the existing ones. I see the ones used on the upgraded modules can I use those values? I'm not sure if I will need to change the resistors or not in those areas.

Film caps are generally more reliable than electrolytic and more linear so there should be less room for improvement from replacing them.  Again you can answer the question yourself by modifying a channel and seeing what difference it makes.

I am new to all of this but not afraid to get my hands dirty and have a few channels not in use to learn on.  :-\

I have yet to build a new power supply, thats next on my list... any advice (amperage or configurations) for a supply would be greatly appreciated. I am aware of the Acopian builds and some prebuilt ones I've seen on ebay.

Thanks in advance for any help.

Good luck... perhaps search the forum for other similar projects.

JR

Thanks for your input. You make a great point. I think I needed someone to just tell me what I was already suspecting. I don't want to fully loose that (dare I say) "EDGY" sound I get from the stock modules but I wouldn't mind getting a slightly different take on said signature. Hell I don't even know if I have heard the console the way it was meant to be heard of the production line. The caps look like they have never been changed since it's birth. Baby steps I guess.

 

[ln76d]

1.) My question is do I keep the same radial cap values as the originals? 
I had 4 channels upgraded by Jim Williams and the caps were beefed up while using Wima Film Capacitors on backside of module I'm assuming to compensate for the increase? My questions is should I keep it stock values or beef them up? It's more cost effective to keep stock values. I do like the sound of the upgrade but I was hoping to achieve an overall better sound on the unmodded channels by just recapping and by changing the IC's in certain areas (preamp, line input, and fader).

Wima caps from the backside are for "bypass", which Jim likes to add in most of equipments  which he modded.
I've never heard any improvement by doing that, but maybe this depends on appilcation.
Higher capacitance in filtering sections can improve hum issues in audio path is for extending low frequency response.

2.) Should I change all the Film Caps as well? I don't know the values I need for those as they are not clearly marked on the existing ones. I see the ones used on the upgraded modules can I use those values? I'm not sure if I will need to change the resistors or not in those areas.

If Jim replaced resistors, he probably used Dale RN55/RN60.
If there wasn't value change, it's not necessary.

Do you have schematic or service manual (or any link for it)? If so, place it here so we could look what can be done

 

[JohnRoberts]

1.) My question is do I keep the same radial cap values as the originals? 
I had 4 channels upgraded by Jim Williams and the caps were beefed up while using Wima Film Capacitors on backside of module I'm assuming to compensate for the increase? My questions is should I keep it stock values or beef them up? It's more cost effective to keep stock values. I do like the sound of the upgrade but I was hoping to achieve an overall better sound on the unmodded channels by just recapping and by changing the IC's in certain areas (preamp, line input, and fader).

Wima caps from the backside are for "bypass", which Jim likes to add in most of equipments  which he modded.
I've never heard any improvement by doing that, but maybe this depends on appilcation.
Higher capacitance in filtering sections can improve hum issues in audio path is for extending low frequency response.

Not to second guess Jim, but he probably substituted modern higher bandwidth op amps. A stiffer supply could be useful to prevent spurious oscillation, so what you didn't hear is probably why he did it.

JR

2.) Should I change all the Film Caps as well? I don't know the values I need for those as they are not clearly marked on the existing ones. I see the ones used on the upgraded modules can I use those values? I'm not sure if I will need to change the resistors or not in those areas.

If Jim replaced resistors, he probably used Dale RN55/RN60.
If there wasn't value change, it's not necessary.

Do you have schematic or service manual (or any link for it)? If so, place it here so we could look what can be done

 

[ln76d]

Not to second guess Jim, but he probably substituted modern higher bandwidth op amps. A stiffer supply could be useful to prevent spurious oscillation, so what you didn't hear is probably why he did it.

JR

I didn't saw his work on trident from this topic, but my guessing is based on several Jim posts on several forums.
He's using in many circuits (preamps, microphones) bypassing foil caps to lower ESR of electrolytic etc. For example 100nF in paralell to the electrolytic in audio path. It should be sonic improvement with "more air" or something like that
I've been using many different "modern higher bandwidth op amps" to upgrade different equipment and for oscilation usual decoupling caps from power rails to ground were enough. Sometimes higher filter capacitance does the job too.
There's a many really fine newer opamps (of course everything depends on the overall circuit), but this whole fun with upgrading  made me realize that i really like good old NE5532, especially from signetics/philips (yes i hear the difference between them and texas or jrc )

 

[Trench Studio]

I bought Phillips (NOS) NE5532's for the fader section with a 33pf being install in the open slot on the PCB. I got a handful of OPA134's and TLE2071ACP's for a mix n match sonics shoot out. I decided to leave all the caps stock value but upped them to the FC series Panasonics +105C series caps. I am awaiting shipment from mouser...should be here tomorrow.

As for the Wima film cap bypass I talked with Jim and this mod is now obsolete, he mentioned using and a cap free design now with jumper wires. I'm not sure I want to go that modified on this console as I would like to keep some fashion of the dirty "Trident" sound in place as I do a lot of dirty heavy rock and metal.

Going to build 2 strips then I will A and B what combo sounds/feels right for my application. If any one has any tricks or tips I'd love to hear them before the soldering begins.

I have the schematics and most other documents for the console somewhere I have been searching for them in my garage... if and when I find them I will upload what I have. I was hoping to locate something on here in the meantime but all the links to said specs are dead links now.

 

[ln76d]

Could you repeat about "jumpers"? That's something new  What he's doing with those "jumpers"?
Schematic is the best part to start.
You can look for Panasonic FM also, they are usual cheaper and have better specs than fc.
In audio patch, the best capacitor is no capacitor, but if it need to be - bipolar are fine (not always of course) and if the values are small (sometimes - usual not)  up to 10uF you can look for film caps instead electrolytics. For small values ceramic capacitors you can look for ceramic NP0 or C0G. Without schematic it's  only guessing

 

[Andy Peters]

Could you repeat about "jumpers"? That's something new  What he's doing with those "jumpers"?
<snip>
In audio patch, the best capacitor is no capacitor, but if it need to be - bipolar are fine (not always of course) and if the values are small (sometimes - usual not)  up to 10uF you can look for film caps instead electrolytics.

I think his current mods involve using op-amps with very low DC offset. In a circuit with such low offset, especially when it has unity gain, or the gain isn't substantial, you can DC couple stages. To do that in an existing circuit, you yank out the coupling cap and replace it with a wire jumper.

-a

 

[ln76d]

Thanks Andy! DO you know any opamp with such low DC offset? I would look for datasheet and specs

 

[Trench Studio]

I meant to get the smaller 33pf disc cap to the right in the photo. Can I use the ones I mistakenly ordered or are they too big and will not serve its intended purpose? Its going in the empty C38 postion by the fader opamp. Incase you can't see the photo the ordered disc cap is 33pF 3Kvolts 20%.

Thanks guys!!

 

[Trench Studio]

So I recapped all of the channels of the console with Panasonic FC caps. I kept all the same values as the stock sizes. I used OPA 134's on all of the mic pre locations, used the NE5534 on the fader section with the 33pf cap installed after the ic, and used the stock TL071cp for the EQ sections. I cleaned and lubricated all the EQ, Pre, Line and Pan pots as well.

I am noticing the board sounds (for lack of a better word) clearer. My concern is that the low end is less tho. Maybe it is because the top end has returned and now it doesn't sound as muddy?? I also noticed that during tracking drums I normally would flip the phase on my overheads (9.8 out of 10 times) based on my usual set up and I am not hearing a noticeable difference like I did before the recap. I look at and listened to the tracks I captured and it appears correcr if not better in the low end than before but it's so hard to truly tell because I got "used" to the worn sound from before.

Is this normal? haha!

P.S. Would wima film cap bypassing on the caps after the opamps improve/increase/stabilize any low end issues if there were any?

Thanks in advance,
John

 

[PRR]

> the smaller 33pf disc cap to the right in the photo.

Don't see photo.

Not important because I can guess what jobs a 33p would do in audio.

> the ordered disc cap is 33pF 3Kvolts 20%.

You need 30V, you got 3,000V. Well, if your power supply goes crazy over-voltage, these caps will be the last thing to blow. If they physically fit, they are probably fine. If not (or they are VERY oversize), then you should get 50V or 100V caps. A 33pFd may not come in very low voltages, it would be impossibly tiny for no good purpose.

I'd also say that a 33p will NOT "get old" and will NOT "have a sound" in audio systems. It is the BIG caps which carry the sound and give problems; caps like 10,000pFd-1,000,000,000pFd (0.01uFd-1,000uFd), which can't (for practical size/cost) use glassy insulators and must fall back on less-perfect/stable stuff like aluminum rust. So unless obviously broken, I would leave what is there and look elsewhere for improvement/alteration.

 

[JohnRoberts]

> the smaller 33pf disc cap to the right in the photo.

Don't see photo.

Not important because I can guess what jobs a 33p would do in audio.

====

I'd also say that a 33p will NOT "get old" and will NOT "have a sound" in audio systems. It is the BIG caps which carry the sound and give problems; caps like 10,000pFd-1,000,000,000pFd (0.01uFd-1,000uFd), which can't (for practical size/cost) use glassy insulators and must fall back on less-perfect/stable stuff like aluminum rust. So unless obviously broken, I would leave what is there and look elsewhere for improvement/alteration.

Agreed age will not be a problem (film or ceramic).

Not to get all esoteric but...  Guessing a 33p may be a compensation cap used with a non-unity gain stable op amp (like 5534)  or the HF pole across a NF resistor (more likely).

If it's a compensation cap, any non-linearity will only affect the open loop transfer function linearity which will have a much reduced impact on the closed loop transfer function.

If it is a LPF used across the feedback resistor, it will probably be tuned for higher than 20kHz. One would expect that such caps would have little impact on the lower audio frequencies and distortion above 20kHz to be innocuous.  The inconvenient issue with that ASSumption is that intermodulation distortion caused by say a close mic'd cymbal crash could contain enough HF energy to create audible frequency IM distortion products from a nonlinear cap (voltage coefficient).

Note: I am not suggesting that this is a significant problem. Actually pretty low on the list. Only advising that even poles tuned above human hearing, "could" cause audible IM artifacts.

A suitable film or cog/npo ceramic cap should be completely neutral sounding. 

JR

 

[Trench Studio]

Thanks guys. That was an older issue. I ended up ordering and using 33pf 50v caps instead of using the the 3000 volt ones. The 3k's  fit but I felt it was way too over kill. I was told to use the cap after the fader sections opamp if I went with the 5534's (which I did). Had I left the stock TL071 chip there it would have been fine without the cap.

The board sounds much different now with the new caps than it did with the old caps. I got used to the old (muddy) sound.