BA-3 Balanced/dual mono Preamp Nelson Pass design

[brownaye]

 

 

Hello, I'm selling my BA-3 preamp.  Class-A, no-feedback preamp circuit designed by Nelson Pass and released at 2011 Burning Amp festival. I built this as balanced with dual-mono super-regulated power supplies.

 

I built this pre in 2018 for about $1500 (and a bunch of late nights), specifically to drive a pair of diy FirstWatt F4 balanced monoblocks with CLC psu’s I built previously. Killer pairing into horn systems. Clean and quiet with endless headroom.

 

I don’t use it much since moving to a pc-based active crossover system. I’m asking $1400 plus shipping costs and 3% PP fee/or pay as friend.

 

The circuit will accept a single-ended source; simply route the incoming audio ground to pin 1 (and signal to pin 2. The preamp will output balanced regardless of the source.

 

Volume is controlled by a 4-deck, 24-step GoldPoint audio taper attenuator. Resistors are metal film IRC RC55’s: ¼ watt, 0.1% tolerance per Goldpoint’s excellent recommendation.

 

Gain transistors are all matched at normal operating temperatures by Diyaudiostore.com. Each channel has a toroidal power supply with Salas UltraBiB SSLV1.3 regulators. https://www.diyaudio.com/forums/power-supplies/322411-salas-sslv1-3-ultrabib-shunt-regulator.html#post5427621.

 

The result is a really nice sounding preamp.

 

Dead nuts quiet with my La Scalas.

 

For exhaustive details, specs, variations and discussion please see: https://www.diyaudio.com/forums/pass-labs/201281-burning-amp-ba-3b-balanced.html#post2739404 and https://diyaudiostore.com/collections/pre-amplifier/products/burning-amplifier-gain-stage-for-ba-3.

 

 

I'm in Southern NH USA and will happily meet anyone within 100 miles of Manchester. Otherwise, I can ship double-boxed anywhere at the buyer's expense.

 

 

 

 

[brownaye]

[brownaye]