Search found 59 matches

by Paul Barker
Tue Jun 07, 2005 1:12 pm
Forum: Pb Place
Topic: Yorkshire Boatanchor event
Replies: 28
Views: 37119

Hi again Jarek, at 90mA gm is stated to be 5, mu 25. I don't have transfer curves to predict what it might be at my operating point. It has the benefit of the extra dissipation 350w if used below 100mcs with ambient cooling conditional upon really good heat sinking connectors, particularly anode. It...
by Paul Barker
Tue Jun 07, 2005 10:32 am
Forum: Pb Place
Topic: Yorkshire Boatanchor event
Replies: 28
Views: 37119

I could have discussed this in that secret place where you get hit by the mob if you tell anyone it exists, but I know Steve and Dave, key witnesses lurk here, it seems you too, so we have a quorum. This is a public place afaik. Anyone that isn't visiting is missing out, and quite honestly isn't mis...
by Paul Barker
Tue Jun 07, 2005 10:04 am
Forum: Pb Place
Topic: Yorkshire Boatanchor event
Replies: 28
Views: 37119

What Vry means is that because you are only inetrested in tweeter frequencies the air cap coupling inside the amp (or perhaps a pair) has sufficient pass point. You can of course tune if you get air variable caps. Maybe a vacuum cap and an air variable in parallel if more required than is available ...
by Paul Barker
Tue Jun 07, 2005 6:12 am
Forum: Pb Place
Topic: Yorkshire Boatanchor event
Replies: 28
Views: 37119

Good day Steve, I think I'll go dual mono so that I'm not shuntiung so much current. I could then use one 572b within it's ratings at say 100mA for the first stage of filtering and then use the ty4-400 for the second stage to shunt 200mA. The output stage would probably run at 130mA, the other stage...
by Paul Barker
Mon Jun 06, 2005 10:18 pm
Forum: Pb Place
Topic: Yorkshire Boatanchor event
Replies: 28
Views: 37119

sorry guys last post was meant for another forum, woops.
by Paul Barker
Mon Jun 06, 2005 10:12 pm
Forum: Pb Place
Topic: Yorkshire Boatanchor event
Replies: 28
Views: 37119

the one you describe as "Believe it or Not. This Amp Had a Discman Feeding it and Sounded Magnificent" is Mark's Amity under continuous development in Aurora direction. "This is One Evil Looking Beast" is Jonothan Noble's globe 45 amp with trick outpout transformers. It was the m...
by Paul Barker
Mon Jun 06, 2005 10:01 pm
Forum: Pb Place
Topic: Yorkshire Boatanchor event
Replies: 28
Views: 37119

I have to say it's a big mistake phoning Vry because when you eventually get off the phone your head is full of all sorts of ideas thrown out by a mathematician. I only just ordered at great expense Mundorf Silver Golds to hopefully be the final tweak for the Ariels and Vry is telling me to build a ...
by Paul Barker
Mon Jun 06, 2005 9:54 pm
Forum: Pb Place
Topic: Yorkshire Boatanchor event
Replies: 28
Views: 37119

Yes, I just spent all evening on phone to Vry, he put me right off the prefix series reg idea, though I do have some 13e1's which could do it. Like you say rdc is not a problem at all. Did I say how good the capless supply is in the driver part? Recovery from transients is instant, gives the impress...
by Paul Barker
Mon Jun 06, 2005 6:20 pm
Forum: Pb Place
Topic: Yorkshire Boatanchor event
Replies: 28
Views: 37119

Jarek thanks for coming in. I have already built the supply for the px25 part using two stages of 572b and compared to solen caps it's a revelation. Thanks for the tips on using vr's. I'd better look out for those higher voltage ones then. I didn't however have a problem getting the 20 75/60's to li...
by Paul Barker
Mon Jun 06, 2005 7:07 am
Forum: Pb Place
Topic: Yorkshire Boatanchor event
Replies: 28
Views: 37119

Yorkshire Boatanchor event

The event was a resounding success. I'll be linking a web page for it when built. I'd like to use my area here to discuss with Steve Bench and you dave where to go from here in development of my 212 power supply. On the face of it that may seem a stupid question. I used Steve's resistorless capacito...
by Paul Barker
Thu Apr 21, 2005 5:13 pm
Forum: Transformers
Topic: Bass only SE OPT on AMCC1000...
Replies: 15
Views: 14405

It should have been easier to spot that nut, I must be more out of touch than I thought.

Paul the plumber.
by Paul Barker
Thu Apr 21, 2005 6:37 am
Forum: Transformers
Topic: Bass only SE OPT on AMCC1000...
Replies: 15
Views: 14405

Ahh, I've just realised who you are Shinebox. That sound on your Martin Logans was excellent, but yes we were driving those poor 4212's at the top of their ability and still the panels wanted more. We were getting compression. I think you are mad though with all your ideas, but the occasional phone ...
by Paul Barker
Wed Apr 13, 2005 11:50 am
Forum: Transformers
Topic: Push-Pull transformers and gaps.
Replies: 19
Views: 22591

"the physical machine winding time is trivial compared to the taping, insulating, lead attachment etc. and this is often more work for a PP trannie." You're not wrong. Drives you mad when you spend all that time and it didn't work anyway. I have bobbins full of wire all over the house whic...
by Paul Barker
Wed Apr 06, 2005 11:47 am
Forum: Transformers
Topic: 1:1 bifilar output to remove the parafeed coupling cap.
Replies: 31
Views: 37037

I can't promise anything James but just might have an 833 output stage in one of these forms for June. Trouble is I have a so much day job work to do, time is at a premium. I do have the 2kv power supply that could handle the current though. However a 300ma ccs is a bit of a task, is that an easy jo...
by Paul Barker
Wed Apr 06, 2005 7:19 am
Forum: Transformers
Topic: 1:1 bifilar output to remove the parafeed coupling cap.
Replies: 31
Views: 37037

OK I missed an option. A ruddy great big core 1:1 IT capable of handling 300mA dc Dan Marshal bridgeing cap! That might be the shortest route to a good result.
by Paul Barker
Wed Apr 06, 2005 6:53 am
Forum: Transformers
Topic: 1:1 bifilar output to remove the parafeed coupling cap.
Replies: 31
Views: 37037

Dave, thinking on similar but different lines for higher voltages. I want to try an 833a output instead of my 212. The JAmes Transformers are just 40 watt rated at 130mA dc I think. I was planning to parafeed so that the 200 to 300 mA dc current didn't have to be handled by the OPT. I would also con...
by Paul Barker
Tue Mar 29, 2005 6:40 pm
Forum: Transformers
Topic: How come transformers sound so good?
Replies: 5
Views: 7100

Oh I see what you mean now. Exactly the aim is to increase power at each stage of the amp.

Now you wouldn't want me using mosfets would you?
by Paul Barker
Mon Mar 28, 2005 7:29 pm
Forum: Transformers
Topic: How come transformers sound so good?
Replies: 5
Views: 7100

Quote "I find it very interesting that the gain of the PX4-211 combo is about unity. I know you have tried various combinations and trust your ears on this... But I still find it suggests something interesting about the 212 grid and the requirements to drive it "properly" No the px4 a...
by Paul Barker
Mon Mar 28, 2005 1:38 pm
Forum: Transformers
Topic: How come transformers sound so good?
Replies: 5
Views: 7100

How come transformers sound so good?

Just wound a pair of interstages out of EI120. That is the back of the E is 120mm the rest follows scrapless dimensions. Fairly much the same as an imperial 120. There are 4 sections per side of 1180 turns 0.212mm wire which is six passes per section. I've connected series parallel on the input to g...
by Paul Barker
Sat Mar 26, 2005 10:42 am
Forum: Transformers
Topic: a new Bridged cap IT
Replies: 4
Views: 4946

What happens if you use a step down transformer with a cap? Say with a 2:1 tranbsformer, cap is sized to pass LF to the lowest frequency of interest, would you get the best of both worlds? That is 1/4 the output impedance of the driver but equal voltage pass on?

Paul
by Paul Barker
Mon Mar 21, 2005 1:11 pm
Forum: Transformers
Topic: Using Bifilar Wire
Replies: 20
Views: 17623

Sorry guys I have completyely lost interest in this tranbsformer. It isn't big enough for my needs. The source of bonded bifilar is too expensive for me to go any further. New question, how is the dialectric tension between two single strand wires wound together? Shall I try that next? What do you t...
by Paul Barker
Sun Mar 20, 2005 9:06 am
Forum: Transformers
Topic: a new Bridged cap IT
Replies: 4
Views: 4946

Just a bit of parallel thinking. What if you had some cheap 1:1 transformers available to you, but instead of passing hf with a cap, you used a pair or more of these transformers in series (with the obvious benefit of being able to parallel or series the windings to arrive at required ratio), in the...
by Paul Barker
Sun Mar 06, 2005 9:41 am
Forum: Transformers
Topic: Using Bifilar Wire
Replies: 20
Views: 17623

OK maybe now it has to be time for listening. That might take a little longer. Don't forget no gap doesn't exist it's but gap in slab stacked lams isn't it? There is maybe more dc protection in that construction at 13ma than you are allowing for. The dc current figures are calculated from the ccs fo...
by Paul Barker
Sat Mar 05, 2005 12:11 pm
Forum: Your name here.
Topic: 304tl project
Replies: 2
Views: 6712

Thanks for the mention on your page.

You won't go far wrong with copper gm70. Shame I only have a pair, have plenty of Graphite but I don't value their sound much. When you hear better valves you go right off the ones you arrived there from.
by Paul Barker
Sat Mar 05, 2005 9:33 am
Forum: Transformers
Topic: Using Bifilar Wire
Replies: 20
Views: 17623

I have a new set of inductance figures based on a re look at the calcs. Gap 4ma 8ma 13ma 0 159h 64h 21h 1 62h 48h 20h 2 42 35 19 3 31 29 18 So 1.5 post it notes with a target of 8mA looks useable yet durable. I'll try a few gaps for sound and get back to you guys. Paul
by Paul Barker
Fri Mar 04, 2005 9:04 pm
Forum: Transformers
Topic: Using Bifilar Wire
Replies: 20
Views: 17623

Hi again Dave et al OK I did a little work 4 8 0 0.027 89 0.068 35 1 0.07 34 0.09 26 2 0.105 23 0.125 19 3 0.143 16.85 0.152 16 The chart hasn't copied brilliantly 4 and 8 are milliamps dc 0,1,2,3, are numbers of post it notes ac voltage in at 50hz in each case was 5.35 volts Cap size 22.5 uF 0.027 ...
by Paul Barker
Thu Mar 03, 2005 8:30 am
Forum: Transformers
Topic: Using Bifilar Wire
Replies: 20
Views: 17623

Thanks Dave, I expect the lams are scrapless. In any case the dimensions are roughly. Central protrusion of E 25mm Each outer limb 25mm Back of E 75mm with 40mm stack. I'll do the further testing in a matter of days. The output of the sig gen is severely suspect and the Fluke 87 may not be reading c...
by Paul Barker
Wed Mar 02, 2005 10:35 pm
Forum: Transformers
Topic: Using Bifilar Wire
Replies: 20
Views: 17623

Can someone check my maths, in the past this was easy for me, but I've been out of it for a few years. Just wound a 40mm st6ack of EI 75 ( back of E is 75mm long) M6 sil. Managed 3,277 turns. Put 18ma ccs on one winding and injected 10hz into other 4.29v rms measured at input, 22uF cap at output 0.9...
by Paul Barker
Mon Feb 21, 2005 9:02 pm
Forum: Transformers
Topic: Using Bifilar Wire
Replies: 20
Views: 17623

I also take my wire off the top of the spool and then pass it through a felt guide and a wheel. I also have to hold it between thumb and fingers to better tension it. I find that if you go too fast when taking wire off the top it whips itself into a knot. I believe cone shaped cover with a hole in t...