Balancing Neve 82 series direct outputs

[cariocaman85]

Hello,

While we are reccaping our beloved Neve 8232, we are wondering about some upgrades.
There are 32 direct outputs (one from each bus feed, after the bus fader), that are currently unbalanced (common ground, hot, no cold). We are using them and they work fine, but they miss the punch and the fat sound that the output card with transformers are adding. Unfortunately we only have one card with the transformers, and they seem impossible to source...

So we thought about balancing the direct outputs with "close enough" transformers to get a more patch friendly signal and a "warmer" sound.
We've got a few options :

Active ones:

Carnhill unbalanced to balanced circuit from audiomaintenance
Carnhill transformer driver from audiomaintenance

Or passive ones:

Carnhill transformers
VTB2280 Carnhill 600r/600r gapped
VTB2281 Carnhill 600r/600r ungapped
or 10k-10k more input oriented VTB9071

or Edcor series like :
WSM600:600
WSM10k:10k
or the TTPC matcher series audiotransformers 10k:10k or 600:600

Of course passive solutions are more cost effective...

What do you think?
Thanks a lot

 

[ruffrecords]

I left Neve before the 8232 was designed so I am not very familiar with it so can I ask a silly question. Why don't you just sniff the channel inserts on the patch bay. That's the kind of thing they were intended for.

Cheers

Ian

 

[cariocaman85]

I left Neve before the 8232 was designed so I am not very familiar with it so can I ask a silly question. Why don't you just sniff the channel inserts on the patch bay. That's the kind of thing they were intended for.

Cheers

Ian

Thanks for your reply Ian,
The inserts are active and a tiny bit noisy in my memory, but you're right, I should give it a try.
The thing I'm after with the use of these direct output with transformers is also adding some of the weight that I otherwise get from the vt24499 transformers of the rear bus cards.
I like the way they impart the sound, and would like to go in this direction.
Unfortunately I have only one of those fitted with the vt24499 and can't find anymore of those...
One advantage of using the direct outs would also be the bypassing of the fet routing plus having 32 instead of 24 separate outputs.

Regarding the transformer choice I think more of vtb2280, but I hope it will not mess with the rest of the circuit. Is this carnhill 600:600 right with this application?

I will post the section schematic as soon as I get back to the studio, if this is allowed by the rules of the forum?

Thanks a lot

 

[ruffrecords]

There should be no problem posting the schematic here.

If you want to direct out right after the fader then you really need an output stage. The Audiomaintenance one looks like a modern version of the old class A output stage so it ought to give you the sound you are after. The only problem with using that is it needs a 24V supply and I don't know what supply your console uses because at some point after I left in 1976 I think they moved to split rails.

Cheers

Ian

 

[cariocaman85]

There should be no problem posting the schematic here.

If you want to direct out right after the fader then you really need an output stage. The Audiomaintenance one looks like a modern version of the old class A output stage so it ought to give you the sound you are after. The only problem with using that is it needs a 24V supply and I don't know what supply your console uses because at some point after I left in 1976 I think they moved to split rails.

Cheers

Ian

Thanks Ian!

The power supply is providing unregulated +22v and -22v (among other voltages) that is then regulated on each channel board.

I see a regulator on the card, but not sure if that would be ok for the powering. I will send audiomaintenance an email.

 

[ruffrecords]

Thanks Ian!

The power supply is providing unregulated +22v and -22v (among other voltages) that is then regulated on each channel board.

I see a regulator on the card, but not sure if that would be ok for the powering. I will send audiomaintenance an email.

OK, they probably regulate locally to 18V or 15V because I think this is a mostly op amp based console.

Cheers

Ian

 

[cariocaman85]

OK, they probably regulate locally to 18V or 15V because I think this is a mostly op amp based console.

Cheers

Ian

Absolutely,
On the channels +-22 are regulated to +-18v for the audio and +-15v for the logic.

I m wondering if the purpose of the regulator on the audiomaintenance balancing driver card is to regulate that kind of unregulated power, if 22v would be close enough to 24v and if power consumption would be ok for the Neve PSU.

Thanks

 

[ruffrecords]

I have not seen a schematic of the Audiomaintenance driver card but I suspect it is a modern clone of the BA283 output stage. This means the big semiconductor on the heatsink is the output transistor rather than a regulator.

Cheers

Ian

 

[brucega]

What about the AML-16-018?

It uses split rails and would fit the correct voltage, though a little higher cost.

 

[nielsk]

These consoles were available with transformer outputs, as I recall they were 8 channel cards for the groups / direct outs. They have the "pumpkin" VT24499 transformers on them.
I have seen them available for reasonable cost in the past (most folks are after the '80 series components).
The cards simply replace the existing output cards (without transformers on them)
By far the easiest option and sonicaly in keeping with the console

 

[Skunk Works Sound]

These consoles were available with transformer outputs, as I recall they were 8 channel cards for the groups / direct outs. They have the "pumpkin" VT24499 transformers on them.
I have seen them available for reasonable cost in the past (most folks are after the '80 series components).
The cards simply replace the existing output cards (without transformers on them)
By far the easiest option and sonicaly in keeping with the console

Those would be the BA723 output cards, 6 channels per card (see attached schematic).

 

[blakeyboy]

Hello,

While we are reccaping our beloved Neve 8232, we are wondering about some upgrades.
There are 32 direct outputs (one from each bus feed, after the bus fader), that are currently unbalanced (common ground, hot, no cold). We are using them and they work fine, but they miss the punch and the fat sound that the output card with transformers are adding. Unfortunately we only have one card with the transformers, and they seem impossible to source...

What is the pcb number of the transformer board?
Is it the BA723 described above?
I'm sure I have a couple of those somewhere....

 

[cariocaman85]

I have not seen a schematic of the Audiomaintenance driver card but I suspect it is a modern clone of the BA283 output stage. This means the big semiconductor on the heatsink is the output transistor rather than a regulator.

Cheers

Ian

Ok I understand,
So we would need to regulate this +-22 to 0/24v or +-12V to power them.
I believe I saw an optional card in the manual that does this. I could replicate it as it doesn't seem to complicated.

 

[cariocaman85]

What about the AML-16-018?

It uses split rails and would fit the correct voltage, though a little higher cost.

Yes I looked at this one too.
It seems different in the circuit thought, and doesn't look regulated (no heatsink on the semiconductors), but maybe I'm mistaken.

In the desk, power is regulated on individual channels or on a specified card on each rack.

 

[cariocaman85]

These consoles were available with transformer outputs, as I recall they were 8 channel cards for the groups / direct outs. They have the "pumpkin" VT24499 transformers on them.
I have seen them available for reasonable cost in the past (most folks are after the '80 series components).
The cards simply replace the existing output cards (without transformers on them)
By far the easiest option and sonicaly in keeping with the console

Thanks,

Yes, that would be one part of the solution.
In fact the configuration is this one:

24 multitrack out, on 4x six pushpull outputs. I do have 3 cards without the VT24499 transformers and 1 card with.
The 32 channels are routed to any of those multitrack outputs via the FET matrix

32 channels direct outputs, unbalanced, that are mentioned in a lot of places in the manual, on the patch, in the rack 2 outputs, but never on any schematic of our 3 Manual books. I've wired them and they are fully functional, run at nominal level, and clean.
There is no schematic, so I can only guess : they seem to be picked from the multitrack send of each channel, but before the FET matrix. (They are affected by the multitrack fader send, but not by the routing).
This means I'm not sure about what is the last stage before attempting to balance them.

So there are 2 different sides of the solution, one about multitrack outputs, one about direct outputs.

Finding those VT24499 transformers would be great, As I could get the transformer sound of the multitrack outputs.
Finding those cards would also be great, but I guess a bit more expensive.
We will buy if we find them at a reasonable price.

Balancing those direct output would have several advantages though:
It would be a separate module located in the empty (automation intended) rack of the console. So no modification of the console.
We would have 32 separate outputs
We would bypass the matrix (ours is fine, but I've read nightmare stories).
Having both options would be a real upgrade!

 

[cariocaman85]

What is the pcb number of the transformer board?
Is it the BA723 described above?
I'm sure I have a couple of those somewhere....

Yes that is the one!
723A with the transformers VT24499

I'd be interested

 

[cariocaman85]

here is the schematic of the group control of the channel, with the multitrack output from the channel.
Sorry about the low quality image...

 

[blakeyboy]

Yes that is the one!
723A with the transformers VT24499

I'd be interested

I think I have VT24499 transformers as well....

 

[nielsk]

Many consoles route the direct out to it's channel's # MTR bus out when the DIR button is pressed.
It's been a long time since I used a 8232 but it would be worthwhile to confirm if that is the way it works. The patch point you refer to may simply be a way to access the signal before the routing matrix, if you have a few days to spend pouring over the (terrible) manual or 60 seconds to try it on the console you can confirm.
If you have output cards that are set up for transformers I have a single VT24499 that needs a good home... you are welcome to it. Maybe between all of us you can fill it out!
If you want to add separate D/O it may be much simpler to use another power supply to feed them (especially if you use class A outs as the draw is greater). Power One modules are cheap on Evilbay these days.
I just did this exact thing on an incredibly expensive console that has almost no routing features (current trend, unfortunately), by tapping the post fader buffers and sending them to class A drivers (2nd half 283) then the transformers.
Any way you do it you need a driver to feed an output transformer.

 

[cariocaman85]

I think I have VT24499 transformers as well....

Thanks, I sent you a PM