Search found 369 matches

by Alex Kitic
Mon Jul 17, 2017 7:00 am
Forum: Valves
Topic: The Humble EL34
Replies: 33
Views: 9191

Re: The Humble EL34

The biasing resistor on the lm317 will need to change depending on choice of valve ... and there's a quite a range between ecc83 etc, so let's assume that this is just a potential circuit with quite a lot of maths to do depending on the valves used. I think the PSU is quite ugly too but that depend...
by Alex Kitic
Mon Apr 20, 2015 5:06 pm
Forum: Everyones Projects
Topic: GK-71 as a pentode.
Replies: 47
Views: 7728

I will have another listen this afternoon when I get back from my physio class. Unless it sounds better than it did yesterday it's back to triode mode. PS the driver valve CCS is above the anode. I am not aware of the schematics of your amp. If you are trying to reproduce the RH813 with GK71 (someh...
by Alex Kitic
Mon Apr 20, 2015 7:47 am
Forum: Everyones Projects
Topic: GK-71 as a pentode.
Replies: 47
Views: 7728

And does having a CCS on the driver cock things up feedback wise ? http://rh-amps.blogspot.co.uk/2014/06/rh813-flagship-project.html Yes it does change things a lot. I do not know whether you have a CCS above the anode of the driver tube, or below the cathode? If above the anode the ratio between l...
by Alex Kitic
Thu Apr 16, 2015 10:46 pm
Forum: Everyones Projects
Topic: GK-71 as a pentode.
Replies: 47
Views: 7728

So, the 75v & 5W 20ma zener diodes are 1N5374bg I string 3 together (3 x 75 = 225v) and connect to G2 straight from HT. Is it that simple ? :? Yes, it's as simple as that. I suggest using 5W zeners, and up to 75V. Of course, you could use 2x75 and 1x56V, but 225V is probably a better option. Keep i...
by Alex Kitic
Sun Nov 09, 2014 7:43 pm
Forum: Everyones Projects
Topic: DHT Heater using VCCS - PCB or Kit (Possible Group buy)
Replies: 1114
Views: 135693

pre65 wrote: If you make them to give 20v @ your 230-232v mains then that will be OK for my needs. :wink:
Understood, you need 2 of those. I'll check the availability and let you know soon!
by Alex Kitic
Sun Nov 09, 2014 7:11 pm
Forum: Everyones Projects
Topic: DHT Heater using VCCS - PCB or Kit (Possible Group buy)
Replies: 1114
Views: 135693

My amps are monoblocks so I would need 2. The amps are in the process of a power supply rebuild at the moment (dual mono) so it would be an ideal time to incorporate modified filament supplies. I have to check with the shop where I buy the units of the same type as the one shown in the RH813 blog e...
by Alex Kitic
Sun Nov 09, 2014 2:57 pm
Forum: Everyones Projects
Topic: DHT Heater using VCCS - PCB or Kit (Possible Group buy)
Replies: 1114
Views: 135693

I'd love to try them on my GK-71 but I fear the conversion work is beyond my skill level. :( If you'd like to make a pair for me I would cover your costs, and postage. :) I really believe that's not something you couldn't do yourself - particularly having in mind that you are able to build amps. Th...
by Alex Kitic
Sun Nov 09, 2014 9:16 am
Forum: Everyones Projects
Topic: DHT Heater using VCCS - PCB or Kit (Possible Group buy)
Replies: 1114
Views: 135693

- yes, they are good for GM70... Well, currently working on the RH70 (with GM70 tubes, obviously) I could not resist commenting... The relentless grind of DIYers going towards DC for the filaments, and the various solutions to achieve DC heated filaments has almost had me drawn in the wrong directi...
by Alex Kitic
Sat Nov 08, 2014 2:32 pm
Forum: Valves
Topic: Cheap 4Wpc valve
Replies: 9
Views: 4309

That is why I reacted. Chill out Alex. :wink: I think he meant 'responded' which would be much more appropriate and not require the 'chill out' comment. Correct: "to react" has a different connotation in my native language, and thus in my view. "To respond" is when you answer to a question your tea...
by Alex Kitic
Fri Nov 07, 2014 7:01 pm
Forum: Valves
Topic: Cheap 4Wpc valve
Replies: 9
Views: 4309

The post was not aimed at me - obviously.

But as far as a cheap and cheerful amp is concerned, the link does not lead to a schematic for such an amp... just nice pictures of a compactron tube and it's assembly.

That's why I reacted.
by Alex Kitic
Thu Nov 06, 2014 8:10 pm
Forum: Valves
Topic: Cheap 4Wpc valve
Replies: 9
Views: 4309

Re: Cheap 4Wpc valve

Another interesting one from Thomas Mayer : 6GE5 : get your 12-pin sockets out ! As usual, a beam tetrode used as triode. It seems that for some people tube evolution stopped with triodes... or is it that their knowledge and expertise stopped there? I must say I am bored with "incredibly linear tri...
by Alex Kitic
Wed Nov 05, 2014 5:31 am
Forum: Everyones Projects
Topic: Jumping back in...
Replies: 19
Views: 6719

Re: Jumping back in...

In truth I've had a whirlwind year, changing jobs from part time with 50 mile every day commute + crappy min wage extra job, to a full time much nearer job that I don't like nearly as much, so I need something to distract me from that. Now the clocks have gone back it's time to fire up the solderin...
by Alex Kitic
Fri Oct 24, 2014 2:48 pm
Forum: Everyones Projects
Topic: A Final Go With Vinyl
Replies: 49
Views: 8946

Romy, I wish my Serbian was as good as your English. Then I'd be able to confuse you as much in your language as you do in mine! :D I would like to point out that Roman is Ukrainian, thus his mother tongue or first language is Ukrainian - not Serbian. As for the DL103 - I have read so much praise a...
by Alex Kitic
Sun Oct 05, 2014 8:10 am
Forum: Everyones Projects
Topic: GK-71 - economical build.
Replies: 497
Views: 68020

It's a long thread, and it's taking a long time to unfold - so there's a few issues I remember, and a few I keep forgetting. What I do remember is that HF AC is neither wanted nor welcome. A nasty source of destructive influences that affects the sound. What I forget constantly is whether any of the...
by Alex Kitic
Tue Sep 16, 2014 4:31 pm
Forum: Everyones Projects
Topic: 833A (GU-48) Amp
Replies: 1170
Views: 143432

A pair was on eBay recently for GBP 27K. Didn't sell. Supposedly they retail at USD 250K - the auction stated "HAPPY TO SWAP FOR A CAR OR HOUSE IN FRANCE" I guess the seller would be happy to get anything near enough to what he has paid it... which must be an interesting story... That's why I asked...