twin balanced driver


Well-known member
Balanced line driver project.

I have moved my Tannoy 5A monitors into my living room and now listen to TV, radio and CD/DVD through them . The TV is the hub for all the sources and outputs on a SPDIF optical port. I have S/PDIF to RCA converter and that feeds an Arcam Alpha 6 hi fi amp (into Mission 775s but they are not used much) The Tape out amp feeds a Mackie Big Knob passive controller.

The BK is sort of ok but is NOT a true balanced in, balanced out device and the cable run to the Tannoys is around 6mtrs (about 3 as the crow flits) I therefore wanted a high quality, low Z balanced feed from the BK and landed on a pair of devices from Sparkfun Audio utilizing the 'THAT' 1646 bal chip.

I got caught up in the Big Electronical bits Shortage dint I! But with great thanks to two companies I shall mention later I eventually got two “THATs” and 3 DC to DC converters. I now need a box to build it all in.

I had a couple of years ago bought a “bSky” phantom power supply. It was crap. Low output voltage (abt 45V iirc) and very poor current delivery. So, I wrecked that out and built the bits in that. The photos show a the XLR 3 ins and outs. I kept them and linked them as a stereo input from the tape skts and the TRS jacks can be seen on the other end. The power co ax skt I used, a search through 15years stock of wall rats found me a 12V 1A jobby with a plug to match. I used a DC-DC converter that took a nominal 12V in and delivered 15 0 15V out at about 30mA and that is enough to run about 8 balanced drivers.

The DC DC converter were RS components pt # 6664067 for the 12V in device and 2233641 for the 5 V input converters. They are otherwise identical. I have not tried the 5V version so far but will when I get a mo'.

I am posting this now because I have sat on it a week or more! There is more to tell but I shall wait to see if there is any interest/questions and do it then.



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