Search found 59 matches

by Paul Barker
Wed Apr 06, 2022 8:10 am
Forum: Pb Place
Topic: GK71 Matrix
Replies: 8
Views: 4528

Re: GK71 Matrix

This project stalled a while back. Not sure if and when I’ll pick it up again. Presently listening to pse 801a, quite happily. Building Raymond Bates 6V6 CF amp full of resistors, no signal caps: to find out how it sounds. Was planning a GM 70 amp. But probably best admit that’s stalled too. When yo...
by Paul Barker
Thu Jun 25, 2020 1:07 am
Forum: Pb Place
Topic: GK71 Matrix
Replies: 8
Views: 4528

Like Stephie I’m not far from finding heavy stuff mor challenging to handle. But I’m cheating my age ta the moment. I’ll module it down. Main B+ is definatly too heavy for carrying so that’smgetting wheels!
by Paul Barker
Thu Jun 25, 2020 12:58 am
Forum: Pb Place
Topic: GK71 Matrix
Replies: 8
Views: 4528

obviously the power transformers for the output stage are over voltage, oh, I need both for the current as Im shunt regulating, I have some 250mA chokes and a 500mA choke, so the supplies will be summed at the entrance to the 500mA choke after hwihc it’s mono. I’m using Stephies capacitorles pow...
by Paul Barker
Thu Jun 25, 2020 12:38 am
Forum: Pb Place
Topic: GK71 Matrix
Replies: 8
Views: 4528

ImageImage All I’m using from the old breadboard are the AE amorphous IT transformers.
by Paul Barker
Thu Jun 25, 2020 12:36 am
Forum: Pb Place
Topic: GK71 Matrix
Replies: 8
Views: 4528

Gathering some bits` the Sowter input transformer Im using presently acting unbal to bal for a balanced PP amp. Steve Cresswel’s Barbaric.
ImageImage
by Paul Barker
Mon Jun 22, 2020 2:38 pm
Forum: Pb Place
Topic: GK71 Matrix
Replies: 8
Views: 4528

Thank you Stephie for you’re reply. I’ve made most of my remarks elsewhere but instead I’ll do so here so you can look if you would enjoy that but no pressure. I’m too still working and progress will be slow but I’m excited at the same time. Just quickly GK71 pentode should slot in at 800v...
by Paul Barker
Sun Jun 21, 2020 10:08 am
Forum: Pb Place
Topic: GK71 Matrix
Replies: 8
Views: 4528

GK71 Matrix

I have a few large regrets in life but one was at vsac I was in a small room with a few 2 or 3 stalls and Stephie carried in a big heavy project. Didn’t know who that was at the time. Now I know of course. So I missed my one time opportunity to meet the greatest influence to what little I understa...
by Paul Barker
Sun Jul 03, 2011 7:39 pm
Forum: Pb Place
Topic: Partial Choke Loading of Cathode Follower
Replies: 13
Views: 14154

hi
by Paul Barker
Mon Jun 20, 2011 10:00 am
Forum: Pb Place
Topic: Partial Choke Loading of Cathode Follower
Replies: 13
Views: 14154

It certainly worked a lot better than an EL34 CF.
by Paul Barker
Sun Jun 19, 2011 8:18 am
Forum: Pb Place
Topic: Partial Choke Loading of Cathode Follower
Replies: 13
Views: 14154

What the anodes look like when they almost kiss the 300 watt max dis curve Image
The drive
Image
by Paul Barker
Sun Jun 19, 2011 8:11 am
Forum: Pb Place
Topic: Partial Choke Loading of Cathode Follower
Replies: 13
Views: 14154

Though in the interest of accreditation, its far from my design, loads of prior art on it :-) Ah but there is nothing new under the sun , like everyone's so called current inventions glancing through old books and articles one usually finds their source from 50 years ago which they haven't often ac...
by Paul Barker
Sun Jun 19, 2011 8:02 am
Forum: Pb Place
Topic: Partial Choke Loading of Cathode Follower
Replies: 13
Views: 14154

In the event it powered the 833a's grid perfectly. We watched the drive signal on a scope while it was playing and saw no flattening of the positive peaks whatsoever, there was an equal signwave positive and negative. The 833a sounded better each time we raised the current. We finished up at Nick's ...
by Paul Barker
Fri Jun 03, 2011 8:01 am
Forum: Pb Place
Topic: Partial Choke Loading of Cathode Follower
Replies: 13
Views: 14154

To catch up on this the amp described above worked well but was handicapped by something which I just didn't isolate at the time. Now 6 years later while building a cheap but excessive 6em7 botanchor http://i194.photobucket.com/albums/z10/v1505guy/IMAG0740.jpg http://i194.photobucket.com/albums/z10/...
by Paul Barker
Sun Nov 27, 2005 12:59 pm
Forum: Pb Place
Topic: Power transformers
Replies: 6
Views: 9548

Thanks Chris maybe.

Time we had a session, maybe in the Spring? Will the time ever be right?

Can't get your statics out of my head, are you still persuing those?
by Paul Barker
Wed Jul 13, 2005 9:00 pm
Forum: Pb Place
Topic: Partial Choke Loading of Cathode Follower
Replies: 13
Views: 14154

Well the px25 is just a convenient valve that suits many occasions, I'm always playing with it. I use the px4 regularly it's more middy than the px25, the px25 appears more right. Unlike me many people prefer the sound of the px4 to the px25. I'm not one fopr two stage amps, don't like high transcon...
by Paul Barker
Tue Jul 12, 2005 10:49 pm
Forum: Pb Place
Topic: Partial Choke Loading of Cathode Follower
Replies: 13
Views: 14154

Thanks Jeffrey, In the event the fets blew and I didn't care enough about it to trouble shoot that one. I take it you prefer the sound with a russian teflon just decoupling the higher frequencies then. That would work for me I suppose. I don't think I have an application any more for what I was up t...
by Paul Barker
Tue Jul 05, 2005 8:00 am
Forum: Transformers
Topic: New to Forum, Throwing Out Some Thoughts
Replies: 35
Views: 50891

Yes I'll go with that analysis of SE. You blend your load resistors, and caps (Rikens and Mundorf Silver Gold for instance), vary your topologies and select your valves for the sweetness of sound that suits the rest of your system. If you get a good dht valve line up you can make your heart melt. On...
by Paul Barker
Sun Jul 03, 2005 12:28 pm
Forum: Pb Place
Topic: Partial Choke Loading of Cathode Follower
Replies: 13
Views: 14154

Partial Choke Loading of Cathode Follower

Anyone remember the gm70 design in Glass Audio a few years ago? They had a White Cathode follower with a choke between both triodes. They preferred the sound with the choke in situ. I was just wondering whether the choke has to be sized for all frequencies or whether 100hz upwards would do. i.e. is ...
by Paul Barker
Fri Jun 24, 2005 5:07 pm
Forum: Transformers
Topic: Push-Pull transformers and gaps.
Replies: 19
Views: 21120

Your right there. The base costs about another 20 grand if you go my route.
by Paul Barker
Thu Jun 23, 2005 1:03 pm
Forum: Transformers
Topic: Push-Pull transformers and gaps.
Replies: 19
Views: 21120

Not fair to compasre base performance of an se 2a3 on Ariels with a push pull suped up 300b. Not a level playing field.
by Paul Barker
Mon Jun 13, 2005 7:09 am
Forum: Pb Place
Topic: Transformer versus RC coupling experiemnt
Replies: 2
Views: 5914

Yes I was considering that, but didnt bother to try it because when I tried the bridging cap in other transformers it didn't sound any better. Unlike you guys I don't write notes about what I've wound so I don't know what these trransformers consist of, but at a guess 6 primary 6 secondary a few pas...
by Paul Barker
Sun Jun 12, 2005 2:41 pm
Forum: Pb Place
Topic: Transformer versus RC coupling experiemnt
Replies: 2
Views: 5914

Transformer versus RC coupling experiemnt

The PX25 amp as heard at the recent Yorkshire Boatanchor event had the first stage RC coupled. The valve is ML4, Holco resisto load 14k 1uF Mundorf Silver Gold cap, grid leak on px25 100k holco. Power supply for the amp is -r-c, driver stage takes power straight from same shunt regulated B+ as outpu...
by Paul Barker
Sat Jun 11, 2005 7:58 am
Forum: Pb Place
Topic: Trying Dave's odd ideas about transformer coupling methods
Replies: 11
Views: 21606

"yes, maybe you become the guinea pig but the tests are rarely fatal" One touch and I'm a gonner, but one good thing about -r -c power supply, pull plug and breathe a sigh of relief, all HT gone in an instant. I understand what you mean about tweeter now. Just at moment the caps are to go ...
by Paul Barker
Fri Jun 10, 2005 5:58 pm
Forum: Pb Place
Topic: Trying Dave's odd ideas about transformer coupling methods
Replies: 11
Views: 21606

I must be thick, I don't see where you are coming from. The silver golds arrived today, just put them in, a 1uF as coupler betwixt ml4 and px25, then a 4.7 and 0.47 series cap for the ariel tweeter. the improvement over vintage pio bipassed with 0.056 teflon is only very slight, but it is now better...
by Paul Barker
Fri Jun 10, 2005 6:23 am
Forum: Pb Place
Topic: Trying Dave's odd ideas about transformer coupling methods
Replies: 11
Views: 21606

My power supplies for the 212 amp have thus far limited (masked and dirtied) the better sound I know to be there. Fortunately thanks to your old experiments Steve I have an alternative direction to try than arranging a remortgage for sufficient Black Gates. Not that a r less c less for a 212 output ...
by Paul Barker
Thu Jun 09, 2005 6:16 pm
Forum: Pb Place
Topic: Yorkshire Boatanchor event
Replies: 28
Views: 29179

Thanks Jarek for the thoughts. Over in England the rectifiers are oxide coated U19's roughly speaking 250mA 2k5 max secondary, 30 second preheat. Do you think it best to parallel then or series them to cope with the extra current above 250 mA? In parallel one might hog the work. What do you think? T...
by Paul Barker
Thu Jun 09, 2005 7:49 am
Forum: Pb Place
Topic: Power transformers
Replies: 6
Views: 9548

Power transformers

Peter of Tribute phoned me last night, I feel a real heal not giving him personal invite to the recent event we had. Now I have to organise something else so he can come. It all happened a bit quick in the end and was a much greater success than I anticipated. How many years have I been trying to ge...
by Paul Barker
Wed Jun 08, 2005 1:45 pm
Forum: Pb Place
Topic: Trying Dave's odd ideas about transformer coupling methods
Replies: 11
Views: 21606

Trying Dave's odd ideas about transformer coupling methods

Presently the 212 is it coupled from a px25 using AE bifilar wound IT's. When listening at home on low level I take the output from secondary of these IT's to an opt. I have some parafeed 5k double c cores. Integral to the resultys is that for this part of the amp I have resistorless capacitorless p...
by Paul Barker
Tue Jun 07, 2005 11:15 pm
Forum: Pb Place
Topic: Yorkshire Boatanchor event
Replies: 28
Views: 29179

I don't mean it really Chris, just having a laugh as I'm sure you know. There is so much going on otherwise I'd be glad to almost put it to a vote, we'll see what Dave thinks of the cores first. I suppose vis a vis not underestimating the power needs of tweeters, the answer is to see what power they...
by Paul Barker
Tue Jun 07, 2005 8:18 pm
Forum: Pb Place
Topic: Yorkshire Boatanchor event
Replies: 28
Views: 29179

Dave, yes please you are such a kind sole, I'll have my own place please? That is most useful information, we have a saying a friend in need is a friend in deed. Jarek and Steve included of course, and Mark lurking Uncle Tom Cobbly and All. Jarek, you too are a mate. you too are a big help, and also...