audio-talk

OK, the first caps I used as replacement output caps, were a pair of 2200uF 200V Panasonics. After a couple of hours I had to conclude that they were complete crap! The music was shut in, flat, boring as hell, lumpy in the bass and completely uninspiring. Bypassing them with 2.2uFs didn't help a lot...

Rozenblit uses zener diodes around the regulator for this reason. But they start conducting long before their break up values and it's audible. The TL783 is a HV reg. and should do of course much better than an LM317. If "arcing over" comes with sudden increase in current through the tube my protec...

Now that I've committed to putting this amp in a box, is there any way to protect a reg chip from a rogue tube? 300B arcs over in the OTL I built for Nigel....it takes out the reg chip. 13E1 arcs over in my own amp.....it takes out the reg chip. Seems to be that a tube connected to something solid s...

Them chip regs don't like it up 'em do they Mr Mainwaring?

Hee hee what larks! I know, let's see if that dodgy 13E1 from 10 years ago was really as dodgy as I remembered. Insert into valve socket, fire her up and BANG! lovely purple firestorm, deafening crackle from the associated speaker and one CCS chip no longer working properly. Oh poo I said. Yep your ...

Brought the 13E1 dissipation down to 72% of maximum by increasing the value of the CCS current setting resistors to 2.7R 3W (462mA current is now set). This has caused no ill effects on the sound and will undoubtedly prolong the lives of the tubes. They are now running comfortably at about 70W plate...

Some of the other ingredients; Driver stage uses a Broskie Aikido topology with 6SN7 valves. Power supply for the driver stage will be a Neurochrome Maida regulator. 13E1 B+ supply will be CLCLC, basically re-using the power supply configuration of my Transcendent 300B SE-OTL amps (that have simila...

Have got the amp about as quiet as I can get it, in its current form. I did a few mods to the voltage doubler power supply to the driver stages. So changed the caps in the centre tapped array that does the doubling to a pair of 200uF 500V JJ caps, giving a 100uF 1000V array. This is followed by a 10...

Steve, if you still fancy trying the 13E1s with a little higher B+ remember my offer of the transformers I have spare (I thought I was going to use them for my 13E1 project but it turns out I have some other transformers I had forgotton about...). Secondary 1 = 0-135V @ 1.1A Secondary 2 = 0-7.5V @ ...

I've been having a look this afternoon to see if I can have my cake and eat it with respect to the power supplies. I'll be using a separate chassis for my power transformers and I'm pretty sure I can squeeze in transformers for B+ supplies for both 6C33C and 13E1 valves - would just need to swap a ...

Nice work Steve, glad it's working out so well. Must be a contender for this year's best 13E1 OTL amp competition. Oh, hang on, I've just heard there are no other entrants ... in the world :D Aye, It's interesting that no-one else has thought of using 13E1 in an OTL amp. OTOH it's such a daft idea,...

Tried the older 13E1s (1950s) in the amp for a brief period. These don't have the four extra cooling fins on the anodes that the newer 1960s valves have. One was OK but the other developed two lovely red stripes on its anode, right where both the cathodes were, IOW, it got a little bit hot and bothe...

Having a nice listening session this afternoon after analyzing the amp on the scope and sig gen all morning. It performs really well with the current feedback resistor of 4K7. Tried a few different resistors, higher and lower than the 4K7 and all were worse, in terms of sound. Raising the value (les...

Fab stuff Chris!

Thanks for the write-up Steve and really pleased that you're enjoying the music so much. What you describe is similar to my own experience with the 300B SE-OTL, especially the voices and the imaging, it made my spine tingle when I first experienced it. And to think you were ready to give up on it j...