boroman

Here I am - take a look at my profession @ www.beevinyl.com If you have any questions, let me know!

@Reggaebass EDIT: forgot about one VERY IMPORTANT thing. It's a must to replace the damping material inside the cab. It's very dangerous for health (its "particles") not to mention it will mess with speaker too. Replace with foam that has qual damping factor to the factory "wool". It only needs a bit of damping. Not much. Too thick/too heavy and will mess with cab overall capacity. These all things should be done when you're serious about B15N performance.

I'd say good for years. They key to the sound is to find one with original speaker and original output transformer. What absolutely needs to be done for safety, great sound and reliability is - - re-cap all the power supply - clean and preserve potentiometers - remove "death cap" (can kill you someday, no joke!!!) - replace bias cap and put variable resistor for precise bias setting (on fixed bias amps) - install 3-prong grounded power cable, remove polarity switch wiring - cut the high voltage "protection" circuit from speaker cable (causes hum, can kill your speaker and output transformer, can shock you with +450V) Other things worth doing (if needed): replace the seal between cab and head, re-fit the speaker frame, clean or re-cone the speaker, change the speaker cable to 1/4" connection and good speaker wire What you should NOT do - change caps/resistors in the signal/channel circuit - they have their own sound we do love. And 99,99% times they don't need replacing. Also, don't put 6550 tubes and stuff like that, you'd kill the OT.

If you'd ever need re-cap, preservation, retube or repair of SB12, B15N, let me know. I have worked on like 30+ of them... Still have three on my workbench right now. I always dig more 68-79 era, with thiele cabs and square magnet CTS/Eminence speakers, but it's just my personal opinion... I've gone throught single baffles, double baffles, custom "factory upgrade" speakers (JBLs, Altecs etc). Of course a lot off bass players come to my place and they'd choose the early ones, etc. They all do have the same soul, and they all sound quite about the same close mic-d. Difference is usually in the open space

Will try to post tomorrow! Need to make some shots. But it's the same unit without matamp logo like here: http://orangefieldguide.com/OFG_MAT200.htm - I have never seen another one like this, and these were one of the VERY last ones made. Some resistor values (amp was dead stock) were a bit different than in Ormat schematic I got but they still were stock. E.g. 100k vs 150k resistors etc... might be a just a circuit tweak that happened over the years.

I was able to finally buy one! The first thing I did was full re-cap and screen grind resistor change (bigger value/bigger wattage). So the amp will not blow using current production KT88s which are nowhere near to the GEC KT88 these were designed for. The same sound, more reliability.