My line converter box

My best friend asked me to build him this for his studio, which is shaping up rather amazingly. I now build things for his studio instead of mine, that way I don't have to get all angsty about finding the time to use my studio and the cool things I build for it... he does that. My friend Janelle also was interested in this project for herself (we know each other in 3D and live a neighborhood away.) For the passive side I am just using an Edcor XSM 10K:600 stepdown xformer, no ative circuitry needed. For the -10 unbalanced to +4 balanced conversions I am taking Roger Foote's advice and using a THAT 1646 to drive a 600:600 line output xformr - though I guess the transformr isn't actually needed, my friend wanted it and I couldn't think of any argument against using one. Things were very hectic for me last year so I've only gotten back to DIY recently and slowly. What do P-Pro camrades think of my approach and work so far? Any suggestons? Additions? Opinions (it's dumpster food?)?


This is the schematic using a THAT 1646. The appeal is in the simplicity, small space used and parts count - a circuit that EVEN I can lay out (hopefully).

 

 

The power supply (with the red primered xformer)  is just there to take up room... it's way overkill for this box and the empty circuit board to the right of it is what I'll put the socketed 1646s and the .1uF caps on.

thank you,

Kiira

If you're wanting to do a pcb layout and having problems with it, I'd be willing to do it for you. Not looking for anything in return, just want the practice and experience.

PS. took you long enough to show up here again.

kiira said:

For the -10 unbalanced to +4 balanced conversions I am taking Roger Foote's advice and using a THAT 1646 to drive a 600:600 line output xformr

Click to expand...

As Roger's mentioned, the THAT1646 wants to see a low driving impedance at its input, and I wouldn't trust any -10dB source at the other side of a length of cable to qualify. You may want to put a simple op-amp buffer in between.

Other possibly interesting recent threads:

http://www.groupdiy.com/index.php?topic=31087.0
http://www.groupdiy.com/index.php?topic=31162.0

Good luck,

JDB.

Hi JDB

[quote author=jdbakker]
As Roger's mentioned, the THAT1646 wants to see a low driving impedance at its input, and I wouldn't trust any -10dB source at the other side of a length of cable to qualify. You may want to put a simple op-amp buffer in between.

[/quote]

Well. here is what Roger wrote to me about  whn I asked him about using a 5534:

To be completely proper, you need to drive the 1646/2142 input from a simple buffer like a 5534 in a V follower configuration.

But, I have been using these chips without the input buffer for even longer and there is no audible or electrical issues that I have ever seen. So it can be quite simple... An unbalanced 1/4" input jack connected to the 1646/2142 input with it's output driving a transformer. Any 1:1 will work very well. Ie, Edcor WSM600. That explains the box I use to interface my synth rack to my MOTU DAW system.

The only other parts that are needed are the two .1uF power rail bypass caps per chip.

Click to expand...

I'd be perfectly willing to use a 5534 there, I have a pile of Signetics, but figured, why use them if they're not really needed? Roger said this schematic would be just fine:




Thank you!

Kiira

PS - I am sad to see all Roger's posts gone :-(

kiira said:

I'd be perfectly willing to use a 5534 there, I have a pile of Signetics, but figured, why use them if they're not really needed?

Click to expand...

Sure. If it works in your setup without the buffer, there's no need to add one.

(Were I building such a box, I'd let it depend on its likely usage. If it's always connected to the same (my own) equipment which I know to have sane outputs, there's no reason for the buffer. If I were to take it on the road where it would get hooked up to any and all random devices found at whatever venues I'd visit, I'd add the buffer (plus some EMI protection for good measure)).

kiira said:

PS - I am sad to see all Roger's posts gone :-(

Click to expand...

Yeah. We've lost a lot of good stuff over the past year.

JDB.