Search found 4044 matches

by simon
Sun Jul 14, 2019 1:05 pm
Forum: Everyones Projects
Topic: GM70 PP
Replies: 36
Views: 581

Re: GM70 PP

800mA through a GM70? Sounds like a factor of 10 too high? Or am I missing something with this topology?
by simon
Sun Jul 14, 2019 1:02 pm
Forum: Everyones Projects
Topic: GM70 PP
Replies: 36
Views: 581

Re: GM70 PP

Nuts! You'd convinced me with the space charge scenario! :)

I can't think why a different part of the DC supply might sound different though?
by simon
Sun Jul 14, 2019 9:52 am
Forum: Everyones Projects
Topic: GM70 PP
Replies: 36
Views: 581

Re: GM70 PP

pre65 wrote:
Sat Jul 13, 2019 11:06 pm
So, how would this apply to establishing the cathode resistor value on GM70/GK71 with a 20v filament ?
Well, Nick was making a good case against this when he talked about the space charge. If you look further up I made exactly this point about the 20V fils.
by simon
Sat Jul 13, 2019 11:04 pm
Forum: Everyones Projects
Topic: GM70 PP
Replies: 36
Views: 581

Re: GM70 PP

Indeed. But that's why this hobby is so interesting.
by simon
Sat Jul 13, 2019 10:19 pm
Forum: Everyones Projects
Topic: GM70 PP
Replies: 36
Views: 581

Re: GM70 PP

Well that would make a lot of sense. And probably explains why a centre tap doesn't make much difference.

There are reports though of people preferring the cathode resistor attached to the + rather than -, suggesting there is some difference, but I've never tried it.
by simon
Sat Jul 13, 2019 8:00 pm
Forum: Everyones Projects
Topic: GM70 PP
Replies: 36
Views: 581

Re: GM70 PP

I've always thought, perhaps erroneously, that hum pots were used with AC filaments to find the "balance" point across the filament potential difference where the hum was minimum. I've never used a hum pot but have used a pair of balancing create a centre point approximation of the PD. I'm not sure ...
by simon
Wed Jul 03, 2019 8:52 pm
Forum: Assorted Stuff
Topic: Need ideas - workshop floor covering...
Replies: 4
Views: 253

Re: Need ideas - workshop floor covering...

Tend to agree with Stephen about dust. Best to deal with it at source if possible, but that in itself is a challenge. And it's the finer dust that's most harmful. I have a Record AC400 air filter which filters down to 1 micron to clean the air. It's pretty cheap compared to other makes and noise is ...
by simon
Tue Jun 25, 2019 10:25 pm
Forum: Jokes
Topic: A little light humour
Replies: 1633
Views: 228481

Re: A little light humour

Quite. Sadly the alternatives arent exactly appealing either.
by simon
Tue Jun 25, 2019 7:26 pm
Forum: Jokes
Topic: A little light humour
Replies: 1633
Views: 228481

Re: A little light humour

Gotta love Dave Cregan's hash tag in the replies!
by simon
Sat Jun 22, 2019 8:30 pm
Forum: Speakers
Topic: ariels
Replies: 8
Views: 720

Re: ariels

:(
by simon
Tue Jun 11, 2019 12:48 pm
Forum: Assorted Stuff
Topic: Nothing In Particular
Replies: 10509
Views: 692394

Re: Nothing In Particular

Talking of claims that turned into millions this story is extraordinary really. Amey failed to replace two bollards for over a year and Birmingham City Council fined them under the terms of their contract over £50m. There's a lot more about Amey if you can be bothered to look but their owners, Ferro...
by simon
Mon Jun 10, 2019 10:09 pm
Forum: Everyones Projects
Topic: The Nemesis 813 PP Amplifier
Replies: 321
Views: 15405

Re: The Nemesis 813 PP Amplifier

Yes, they've doubled almost overnight it seems. I emailed Yuriy last night but no reply yet.
by simon
Sun Jun 09, 2019 9:13 pm
Forum: Everyones Projects
Topic: The Nemesis 813 PP Amplifier
Replies: 321
Views: 15405

Re: The Nemesis 813 PP Amplifier

Blimey. I've just looked on ebay - seems I've missed the boat on coppers...
by simon
Sun Jun 09, 2019 9:02 pm
Forum: Everyones Projects
Topic: The Nemesis 813 PP Amplifier
Replies: 321
Views: 15405

Re: The Nemesis 813 PP Amplifier

Supposedly the real goodness of GM70 starts at 1000V. That's too much for me - the amp you heard at Owston has around 550V HT. I've read that some poeple prefer the graphite to the coppers, and they do sound different - the graphite's bass is bangin' man, but once I'd heard copper GM70s I lost inter...
by simon
Wed Jun 05, 2019 1:10 pm
Forum: Assorted Stuff
Topic: Owston 2019 - Listening Impressions
Replies: 59
Views: 2882

Re: Owston 2019 - Listening Impressions

izzy wizzy wrote:
Wed Jun 05, 2019 11:49 am
And at home it's lost the ability for me to just sit down and enjoy the music following up on what Ed and Steve said.
And there's the rub of comparing kit. :-(