audio-talk

It won't help that Thomas Mayer seems to have been burning through the world's supplies of 46's in his recent builds ! That had occured to me plus a valve supplier he recommended to me in the past don't have any. If I could get 5 more working ones I might be set for a very long time. Anyone have id...

The 46 arrived, plugged it in, let it warm up for a while. Turned the amp on and only a tiny buzz. Got a bit excited then had a closer look and no filament glowing. Oh dear. Maybe that's why they had one left. It's weird how a live 46 makes it hum yet a dead one doesn't. Anyway, the 46 may be a dead...

I'm not surprised TBH. I thought they were already unobtainium. I'm guessing Langrex want silly money for the one they've got? Goes to show how much attention I've been paying. They don't want silly money so I bought it. They have loads of valves that aren't sorted or catalogued. It's where I bough...

This has taken a turn I wasn't expecting. Rang Langrex for starters to get some more 46. They only have 1, maybe more but they're not sure. Billington, none. VacuumTubes.net, none. Can't find any online in the few places I looked. Oh dear. Any ideas of other places? Once an unknown, now unobtanium? ...

Cor, this is a journey. I must admit I haven't had much hum trouble from DHT's though I haven't used a lot of old ones like 46's. I have however used 300B, 2A3's ( Sovtek ) , 6B4G's of various vintage, 45's occasionally , 4P1L, GK-71 . I would mainly expect HF oscillation from omitting grid-stopper...

Swapping things around has revealled where the hum is coming from. I did the easy thing first, swapped the 46s over and the hum went with them. Doing some more swapping found the culprit. Wasn't expecting that and so not sure why that would happen. The 46s don't have any grid stoppers, ferrites or a...

SMPS into 2nd channel and it hums :roll: Not the same hum/buzz as before. Thanks goodness I did the other one first. There is one difference I know of between them as this one has a choke in the HT to the driver and maybe it's picking up some stray field. It is quite close to another transformer. At...

I've been having loads of trouble from bad connections in the phono chain lately , so do try & disconnect & re-connect anything relevant, just to make sure there's nothing cruddy in one channel or other. I had speaker swaps & tests that just weren't making sense. Phono signals are so lo...

I've been having loads of trouble from bad connections in the phono chain lately , so do try & disconnect & re-connect anything relevant, just to make sure there's nothing cruddy in one channel or other. I had speaker swaps & tests that just weren't making sense. I started the compariso...

How does the top-end sound, though, with no HF filtering ( I assume these are SMPSs ) ? So I went to compare channels to see if there was something to your question. Tried a few records and was falling for the SMPS channel on soprano and solo piano. Thought I'd made my mind up on the top end in fav...

Do you mean centre-tap to cathode resistor ? (Stephen) Very pleased for you - must be a big relief after all of the mods you've tried. How does the top-end sound, though, with no HF filtering ( I assume these are SMPSs ) ? See above for pics. I got fixed bias now. Relief is part of it. I so wanted ...

Hi Stephen, not sure I fully understand the way you wired those two 10A 5V supplies, a little diagram might help. Thicko country bumpkin. :lol: I didn't get it until I saw it either. Circuit like in this thread https://www.audioasylum.com/cgi/t.mpl?f=tubediy&m=199885 The 833 amp looks like this...

I've come back to this amp after a phono rebuild. I had also sounded out the Joes about my buzz/hum. Despite one person being able to get PP 813s silent on AC, the general consensus among anyone that has these things is DC is the way to go. Those that have 833 or 813 amps SETs use SMPS supplies. Som...

I enjoy watching your process. Great result and well done.

Cheers,
Stephen

Ant, have you not tried the Conrad protractor generator? Need a windows pc to run it. Measure the pivot to spindle distance and choose the curve you want....third one down here: http://www.conradhoffman.com/chsw.htm Thanks Neal. What a great program. I lost my CAD program template. Printed off the ...