Adding a balanced direct out on large fader of Neotek Elite

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Jason Kingsland

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Oct 3, 2021, 7:13:12 PM10/3/21
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Hey all,

I'm still slogging along with my Elite and slowly but surely gaining functionality every week. A long time goal I've had is to add a direct out to the large fader while in reverse mode so that the large fader will feed the mix bus and the direct out and the small fader can feed the busses.

So first, if I'm looking at the schematic correctly it would be possible to tap pin 6 of the 5534(U17) to drive whatever would balance the output. Is that right? Or should it be from the 47 ohm resistor after it?

Secondly, what would you prescribe as the best way to handling balancing the output? I've had a half and half of "PUT A TRANSFORMER IN" and "The THAT 1646 is totally fine". Thoughts? Either way it looks like utilizing the unstuffed molex connectors immediately by the insert send and return would be a convenient non kludgy way of interfacing everything.

Thanks!
Jason

Ike Zimbel

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Oct 3, 2021, 10:03:06 PM10/3/21
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Jason,
        You should tap off after the 47 ohm resistor. Just above the unused Molex header you mentioned is an unpopulated IC socket. It may be possible to populate that area with a active balancing stage. I’ll check the drawings when I get a minute. 

Ike Zimbel,
Zimbel Audio Productions
Sent from my vintage iPhone

On Oct 3, 2021, at 7:13 PM, Jason Kingsland <j.kin...@gmail.com> wrote:


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Jason Kingsland

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Oct 4, 2021, 8:00:06 AM10/4/21
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Thank Ike!

Absolutely, though if that is like the insert circuit above it, it’s for the returns and inputs of the amp are looking at the molex. But maybe some type of adapter board could be a great solution there.

Jason



Le Cowboy Studio

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Oct 4, 2021, 9:13:50 AM10/4/21
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That setup would be awsome. 
If I understand correctly, that way, one could also print every individual tracks while printing the Mix. Recall would become much more easy.

Keep us posted

Le Cowboy Studio

Le 4 oct. 2021 à 8:00 a.m., Jason Kingsland <j.kin...@gmail.com> a écrit :



Jason Kingsland

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Oct 4, 2021, 9:36:14 AM10/4/21
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I’ve been working this way using the busses and direct outs on 27+. It rips. Its the future for mixing on a desk. Makes recall super fast.  Plus once I free up the busses the routing will be incredible. 

Jason

ik...@zimbelaudio.com

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Oct 4, 2021, 10:08:28 AM10/4/21
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I make a little circuit board that supports a THAT 1646. It could easily fit in that footprint.

Jason Kingsland

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Oct 4, 2021, 2:20:59 PM10/4/21
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That sounds incredible, would anyone else on here be interested in something like that?

Jason



Greg Norman

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Oct 6, 2021, 11:50:47 AM10/6/21
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Coming in late on this.  
Our board was built with an additional amp and connector (P13?) stuffed for direct outs, but fed from the signal going to busses.  It’s a unity gain follower amp, unbalanced signal, (but we’ve never had a problem with noise or loading over the 24 years).  This is an option available on the factory PCBs.  It can basically be programmed to use whatever source you want with a jumper.  No daughterboards needed.  I love the THAT1646, and jump at the chance for replacing older IC, cross-coupled transformerless output amps, but it might be a matter of K.I.S.S. with a proven thing.
When I get back to Electrical, I’ll try to update you on the details if you wish.  

Greg Norman
Electrical Audio Recording
773.539.2555
www.electricalaudio.com

Jason Kingsland

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Oct 6, 2021, 5:19:59 PM10/6/21
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Hey Greg,
Thanks for the reply. Attached below is a picture of the rear side of the pcb from the insert section of my console. On this module, the top dip 8 socket(Pin 1 is on the upper right of the dip 8 if anyone is spatially challenged like me) is a tl072 with pins 2+3 (the "A" inverting and non inverting inputs) going to a pair of resistors and the finally the molex header. So if I'm thinking of this correctly, signal is meant to go from the molex to the inputs of the amp. If I'm looking at the unstuffed it appears to be setup in the same configuration, so that no matter what I'm either making adapters or getting down with a lot of jump wire. If I'm wrong, please let me know, cause it would be great to have a simple solution.  Thanks again for everyone's time on this.

Jason
IMG_2443.jpg


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Jason Kingsland

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Oct 25, 2021, 8:42:41 PM10/25/21
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So I ended up running this down and made some PCBs and it worked. I need to make some changes to make it a little less clunky of an install, but still works. It’s a stacking board system so that the top board is just a basic THAT 1646 example circuit, and the lower board adapts it to the inverted TL072 thing I was referring to. The boards integrate to the dip8 pads that are on the desk and then connected to power and signal in and outs with jump wire or 0 ohm resistors(I’ll be reworking the boards to be more dependent on the links and less on the jump wire). I also realized the stereo modules have some useful points on a not utilized 9 pin molex header. So I built an adapter to house 2 of the 1646 boards for direct outs on the stereo modules these will output to 2x 3 pin molex headers. All pictures below. This is my first lark at doing anything like this so any thoughts appreciated. I did get a lot of assistance on the layouts from Timothy Herzog @ Herzog electronics so hopefully that should be good. In any case, just wanted to share. Thanks again everyone.

Jason
IMG_2507.png
IMG_2508.png
DO 1.jpg
IMG_2509.jpg


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Greg Norman

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Oct 25, 2021, 11:40:10 PM10/25/21
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Cool,

Sorry about the delayed response.  Here’s what our board is doing for the first 26 channels (the rest utilize the unused bus o/p amps).

You could make the output “impedance balanced” by removing the pin 2 to 3 jumper on P13 and replacing it with a resistor .1% matched to R905.
In 23 years, we haven’t had any noise or fidelity hiccups with the unbalanced out, however.

Greg Norman
Electrical Audio Recording


On Oct 25, 2021, at 7:42 PM, Jason Kingsland <j.kin...@gmail.com> wrote:

So I ended up running this down and made some PCBs and it worked. I need to make some changes to make it a little less clunky of an install, but still works. It’s a stacking board system so that the top board is just a basic THAT 1646 example circuit, and the lower board adapts it to the inverted TL072 thing I was referring to. The boards integrate to the dip8 pads that are on the desk and then connected to power and signal in and outs with jump wire or 0 ohm resistors(I’ll be reworking the boards to be more dependent on the links and less on the jump wire). I also realized the stereo modules have some useful points on a not utilized 9 pin molex header. So I built an adapter to house 2 of the 1646 boards for direct outs on the stereo modules these will output to 2x 3 pin molex headers. All pictures below. This is my first lark at doing anything like this so any thoughts appreciated. I did get a lot of assistance on the layouts from Timothy Herzog @ Herzog electronics so hopefully that should be good. In any case, just wanted to share. Thanks again everyone.

Jason
<IMG_2507.png>
<IMG_2508.png>
<DO 1.jpg>
<IMG_2509.jpg>

Jason Kingsland

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Oct 27, 2021, 3:10:57 PM10/27/21
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Well a tad late for me but thanks for posting that Greg, it’s super helpful to have that out there. That said the THAT is super nice in that position, and the only jump needed here is from the 47 ohm resistor following the fader buffer amp to the input of the THAT chip on both the mono and stereo modules. So that’s neat. Thanks again!
Jason



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