audio-talk

Is this going to Owston?

Mike H wrote: ↑Sat Apr 06, 2019 7:40 pm Is this going to Owston?

Providing it doesn't blow up before the beginning of June, it'll be going to Owston.
I think it is the bees knees, but then I would wouldn’t I.

I've got a little idea to do with the Fanes too; an idea which Steve S suggested might have potential, last time I visited him.

We might have some good and interesting stuff for this fest.

Mike H wrote: ↑Sun Apr 07, 2019 5:54 pm We might have some good and interesting stuff for this fest.

Aye, just a bit more to do with the cosmetics of the top plate before Owston. All them bolt heads give me the willies.

Cressy Snr wrote: ↑Sat Apr 13, 2019 9:39 am
Aye, just a bit more to do with the cosmetics of the top plate before Owston. All them bolt heads give me the willies.

I hope they are all in line with each other ?

pre65 wrote: ↑Sat Apr 13, 2019 12:01 pm

Cressy Snr wrote: ↑Sat Apr 13, 2019 9:39 am
Aye, just a bit more to do with the cosmetics of the top plate before Owston. All them bolt heads give me the willies.

I hope they are all in line with each other ?

That's the trouble, they are in a random pattern when seen from above the top plate. Maybe I'll embrace chaos and not cover them with a flat piece of aluminium.

Cressy Snr wrote: ↑Sat Apr 13, 2019 1:06 pm
That's the trouble, they are in a random pattern when seen from above the top plate. Maybe I'll embrace chaos and not cover them with a flat piece of aluminium.

KISS.

Had the amp on the 'scope earlier this afternoon and have managed to further tweak up the squarewave response. I mean, it needs to be on its best behaviour for Owston n' est ce pas? Have changed out the 10K carbon comp grid stoppers for 2K2. This has given sharper corners on both the leading and trailing edges of the 1KHz and 10KHz traces.

Was highly wary of oscillation with these valves because of the high 35mA/V gm so I limited the bandwidth with the larger resistors, but I've taken the scope out as far as it will go and am not seeing anything untoward with the 2K2 stoppers.

A nice bit of filigree treble detail and quicker leading edge definition has emerged from wherever it was hiding, so the scope exercise was worth doing. I'm getting to like test equipment a lot.

So output stage grid stoppers should now be 2K2 or maybe the 1Ks that MJ uses.

Just a note about grid stoppers for Ray.
I put a wire link in the 10K position on the driver PCB and put the grid stopper resistors right up against the grid pin on the septar socket.

Cheers Steve

they are in a random pattern when seen from above the top plate

I very much doubt that.

Nick wrote: ↑Sun Apr 14, 2019 7:01 pm

they are in a random pattern when seen from above the top plate

I very much doubt that.

Allright, so I was exaggerating!

Cressy Snr wrote: ↑Sat Apr 13, 2019 3:15 pm
.....So output stage grid stoppers should now be 2K2 or maybe the 1Ks that MJ uses.

Took the carbon comp grid stopper values down from 2K2, to 1K this afternoon, as I found a couple whilst rummaging in the parts boxes and thought I’d give them a whirl. The sound has gone up another notch.
As did Wolfgang, with his 6C33C based amp, I’ve found that this single ended OTL amplifier is highly responsive to slight component changes; much more so than anything else I’ve built.

Interesting.....

Spending the next few hours, painting individually, each top surface bolt head on the mains transformer side of the output valves. I tried making a plate to cover the bolt heads but it looked like crap. That’s me occupied and out of mischief then.