Balancer and De-Balancer on a TRS Jack to upgrade unsymmetrical gear

[Janus Audio]

Hi everybody,

I made SMD boards to balance inputs and outputs of some of my outboard gear, because I often hat hum problems with some devices. The boards are just some line receiver and line driver circuits based on LM4562s and can be fed from internal power supplies of the modded unit (as long it is a true bi-polar power supply). I tested them with up to 20dBu (which is all my DAC can do) and got THD less then 0.0012%

So far I upgraded my Quadraverb, Lexicon, LPX-1 and dbx 163A

Let me know, what you think!

Cheers, Sebastian

 

[TwentyTrees]

Great stuff, that's a very neat and compact solution to the problem. Nicely done.

 

[thomasdf]

Very clever design and neat build ! Bravo !

 

[Janus Audio]

Thank you!
I will test them with syngthesizers next. I sometimes get hum with some synths when they are connected via USB-MIDI

 

[Janus Audio]

Modding the Alesis Microverb II with symmetrical inputs and outputs

Checking the PSU where we can tap into the power rails:


Removing the old TS jacks:


Connect the sub-boards to the PSU V+ and V- taps and to the tip and sleeve solder pads of each TS jack:


Put the cover back in place:

 

[fazer]

Love it nice job.

You use to be able to buy these types of circuit kits from SparkFun for cheap. I wanted to make a hifi amp have a balanced input to work correctly with a balanced monitor controller and finally went to order the complete kits and they had discontinued them. Bummer.

 

[Janus Audio]

Love it nice job.

You use to be able to buy these types of circuit kits from SparkFun for cheap. I wanted to make a hifi amp have a balanced input to work correctly with a balanced monitor controller and finally went to order the complete kits and they had discontinued them. Bummer.

Thanks you!

I didn't know SparkFun yet - looks interesting! I don't see anything similar there though.
I will probably also sell the boards, if I manage to get a listing in the white board section.

 

[JohnRoberts]

these are called "bump boxes" and were popular last century back during the height of the -10 dBV bedroom recording gear boom, to step up/down signals between -10dBV unbal gear and balanced +4 dBu gear.

JR

 

[k brown]

Maybe I've just been insanely lucky, but all my 40+ years mucking about with audio, I've not once encountered noise or interference from using unbalanced connections between line level gear.

 

[JohnRoberts]

Maybe I've just been insanely lucky, but all my 40+ years mucking about with audio, I've not once encountered noise or interference from using unbalanced connections between line level gear.

As you shouldn't using properly designed gear.

JR