Any interest in a multi channel balanced line driver setup?

[Jacampb2]

I am working on a design right now. It will use the Burr-Brown DRV134 and the Burr-Brown INA134 IC differential line driver IC's. I'm thinking I'll use mini din connectors for interconnect, and as of right now, I plan to make it 6 channel, but I could be persuaded to do 8 channel. The problem is, just the Burr Brown chips come out to over $100 for the transmitter and receiver. Each box will also have to have a small switch mode power supply, a few other extraneous parts, and interconnects. You will absolutely have to make your own cables, or, I can buy wire and make them, but this wont be a cheap project.

On a limb, and supposing I can source some decent enclosures for reasonable prices, I am guessing that cost would be under $200. If there are enough people interested, I would hope to be able to get quantity discounts on the BB's-- that's the main reason I am offering. LMK, if there would be any interest. There is no reason that the balanced transmitter side will not work with any esoteric amplifier you may have that has balanced inputs. Anyhow, the BB drivers have excellent specs and high common mode rejection numbers.

Let me know if it seems like something you might be interested in.

Thanks,
Jason

[itchnertamatoa]

I'm game
always am for these type of things ...

[Jacampb2]

Hmmm, well, I guess there is not a whole lot of demand, huh? Itchy, if you want one once I get things all worked out and prototyped I will be happy to hook you up, but there won't be any quantity discount for parts for me to build 2.

For further details on the reason behind this, see bellow:

I was looking for a RCA type line driver and I need at least 6 channels. I had intended to buy a tld66, but it appears that the stock pile of them out there has begun to dry up.

The DRV134/INA134 transmitter reciever pair do the job of both unbalanced (rca) to balanced (xlr/pro audio) to unbalanced (rca) again, allowing you to make long cable runs and cable runs in noisy environments with little to no induced noise showing up in the unbalanced output at the end of the conversion. Think PG TBAT, but in a 6 channel version. The burr brown pair provides 6db of gain, but it is fixed, do to the nature of the IC's all of the resistors paired with the internal op amp are non adjustable, the good news is they are precisely matched, laser trimmed, and will provide better signal balance and common mode rejection than would be physically possible with discrete components. The one draw back is fixed gain. 6db of gain equates to 2X Vin, so if you give it 4V via RCA, you get 8V at the other end of the chain. I can attenuate the receiver end for lower voltage output, but we are not going to amplify it any further.

Anyhow, I will update this thread as I go. If anyone has questions or is interested, let me know.

Later,
Jason

[fuzzysnuggleduck]

How many units are we talking about to get the BB chip prices to come down?

[Jacampb2]

How many units are we talking about to get the BB chip prices to come down?

First price break is at 25 pieces, each you one IC per channel for both the transmitter and receiver. My original estimate on price is incorrect. I was thinking 6 stereo channels which is 12 IC's per box, but in actuality I should have figured on 6 discrete channels.

So anyhow, each transmitter will use 6 DRV134's and each receiver 6 INA134's. This cuts the cost of the burr browns pretty much in half from what I was thinking...

Thanks,
Jason

[Jacampb2]

I got a bit of work done on the schematic, I am at work right now with only the free ware version of Eagle, so I had to keep the schematic size quite small. I have the full version at home, so when I get some time there I will do the full 6 channels and make it a bit easier to view.

Later,
Jason

[Jacampb2]

Oh! I do have the SMPS worked out, but I am out of time for right now. I'll get the design in eagle soon and post the work.

Later,
Jason