Popping the Shunt Voltage Regulator’s clogs

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Not a surprise

What I suspected it was going to happen, it did in the end. Although a bit premature and in a bad time. I’m expecting today a friend to come around for a listening session and having no amp wasn’t an option.

To cut a long story short, the Salas SSHV2 shunt regulator has been playing silly buggers for a long time. Since I upgraded the output transformers and readjusted the bias, it looks like I was operating it at the verge of its abilities. The CCS was running at 80-90mA and somehow the stability of the shunt regulator was compromised. Initially was a periodic lost of regulation during warm up, this created an annoying “pop” now and then,  later I decided to replace it with a new SSHV2 and blew a pair of DN2540 after the regulator failed to set the output voltage randomly. It worked fine on the test bench, however there is something on my system which is disturbing / interfering with the regulator or the regulator isn’t stable enough at the hot operating conditions I was submitting it to.  I have nothing against the SSHV2, in fact, I use it extensively in my preamps. However, I think I’ve found the limit at which it can safely operate. The additional drawback of the SSHV2 is its temperature stability. It’s not great as it drifts when temperature rises.

So the regulator went busted on Thursday evening and I was running out of time. Only Friday was available to fix the amp. Luckily, I was on holidays this week and had the time to fix this, but unfortunately this diverted my energies and time from the 300B amp :( Continue reading


300B Amp: the journey starts here

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I can’t get away from my big HT power supplies. This time the HT +400V for the 300B amp is here. Lots of Lundahl iron and a lovely hybrid bridge made of mercury rectifiers and damper valves. Yes, I’m in love with the blueish colour of the 816s. Despite they are mercury rectifiers, I know.

I promised the wife I’d get a smaller amp, that was my excuse for the 300B reference system. Still this is not going to be small, however, it will be compared to the 814 SE Amp!


01a Preamp Gen2 finished!

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01a preamp gen2 finishedFirst build of 2015, just after the New Year. I’m pleased to listen to the 01a preamp gen2 finished. It’s a beauty, only the warm sound of the 01a thoriated tungsten filaments can provide. A perfect match to the Starlight CD player that was lacking of a bit of gain.

It’s dead quiet, the frequency response is superb and the dynamics are there. Very good bass that improves what I was getting out of the discrete DAC. I love listening to this preamp. A great pleasure. Thumbs up to the return of the 01a. My best Sylvania globe valves are now in use, yay!

Will soon write a proper blog entry for this ultimate preamp.