audio-talk

Bear in mind he's using the driver valves at 3.65W dissipation per plate - too much for 6SN7 or 6SN7GT ( and 12v equivalents ). It needs the higher dissipation GTA or GTB models, I remember this from the Reichert article. You'll need to make sure which ever alternative you choose can take at least ...

A question to the knowledgeable: I'm building up a list of parts required to build this. The circuit diagram calls for a 5Hy 80mA choke in the power supply for the input and driver stage. The nearest I can find in the Hammond range of chokes is the 156L, which is rated for 5H at 75mA. According to t...

Of course, nothing is straightforward... It would be a lot more straightforward if you just choose to run a single filament voltage - do you really need the flexibility to be able to run either 6SN7s or 12SN7s? I think on balance i'm probably going to do that. When I plan these things, I tend to th...

I don't have many 6sn7s, most went years ago, I sold a large box of b65 ecc32/33/35s last year, I have quite a few l63/6j5 types, and I think I have a few b36 and 12sn7, I can test and match them all. Let me know what other type you think of as I still have quite a few 1000 valves Pm if intersted N...

Well, seems 12J5's (single triode equivalent to 12SN7) are REALLY cheap. I'm starting to think, just have done with it and wire up 12V heaters from a separate transformer, 1x 12SN7 in the input position and 2x 12J5's in the driver stage. That would be do-able for even less than buying all-new manufa...

simon wrote: ↑Fri Jul 24, 2020 7:49 am If you're only using half of the 6SN7 perhaps try 7A4s, a well regarded loctal keeping with Mark''s suggestion? They look to still be 10 bucks each.

Ooo... with a 7N7 dual triode equivalent at the input. Thanks for the heads-up on those Simon.

Well, I did want to ensure it could use valves in current production. However, it should be easy enough to make the heater supply switchable (note to self, use a locking switch) between 6v and 12v, seems 12SN7s are still quite thick on the ground. That way I can use either. Well I was just thinking...

The output iron will likely be sourced from here: http://npacoustic.com/en/product-and-price

Amorphous core, bandwidth up to 80kHz, that'll do for me.

These days you'll have more chance of getting good 6SN7 types if you go for other filament voltages. The 6SN7's are awful prices for the good ones. Well, I did want to ensure it could use valves in current production. However, it should be easy enough to make the heater supply switchable (note to s...

Well, for no sensible reason that I can identify yet, I still have a hankering to build a 300B push-pull amplifier - probably monoblocks now, given how my system is configured. Meredith was right - I'll always need a project. I was always attracted by the Lynn Olson designs as the all-differential c...

Thanks all. Hopefully they'll finally make it to Owston in 2021! I'd originally planned to have them there in 2018 but... 2018 - Not ready yet 2019 - Still not ready yet and Owston clashes with trip to Scotland 2020 - Ready, but Covid-19. Things I still need to do: Preamp VU meters - as predicted, a...

I realised I hadn't finished this off properly by sharing the completed interior shots, or any decent exterior shots of the amps working. I photographed them this week in the evening after having got a more up-to-date lens for my proper camera, as the light was getting low. It's actually quite trick...

Gutted for you Ant, that's a real shame. I was admiring that tank of yours last Saturday when I dropped off the RCM, I seem to remember spotting one pretty darned big fish in particular, about 5 inches I think? I was telling Meredith about it only last night, we really want a tank of our own but rig...

Meredith and I did some tweaking to the positioning of the big Mets last night whilst listening to the Darrell Scott albums - just a few centimetres forward and back, and adjusting the toe-in. Seems Meredith's ears are better at picking up changes than mine are, the sound has got quite a bit better ...

Meredith discovered Darrell Scott while I was out on my voyage yesterday - we ended up buying his entire discography on Bandcamp. Superb songs, superbly recorded.