What is this?

[Jack Morrison]

I have a SUNN PB-10 Beta Preamplifier.  It is a 3 space rack mount unit.  I got it in a trade over 10 years ago. It works great but I can not find any information on it.  I assume it is a bass preamp but am not sure.  Does anyone know what this is?

Thanks

[Don T.]

Hello:
 You have the only one in existance my friend. It was built for Bill Stahlin when he was with White Lightning. It was in a rack with a couple of SA 21 amps. It had a standard Beta preamp with a SPL 4120 power supply. It should be a Beta Bass (without reverb control). It used a beta ll switch with an XLR connector. There may have been others built by employees but I don't think so. Does it have a serial number tag?
Don T.