toroidal transformer supplier

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Nick
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#1 toroidal transformer supplier

Post by Nick »

I don't know if people know of this chap, but I came across him after asking Antrim for a quote on a pair of mains toroids for something planned for the future.

http://www.terrymonaghan.co.uk/

I will let you know what they are like when they arrive.
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#2

Post by simon »

It's a numpty question Nick, but what are the advantages of using toroids? I know they're used in SS but valve amp txs are usually EI.
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#3

Post by Nick »

Well, Paul will hopefully be along with the full answer, but I think they have many of the same advantages of a C-Core, less externally radiated hum field. But they will saturate rapidly, and they can leak field from where the leadout wires leave the TX.

Truth be told, the reasons I am using a toroid for this are a bit doubtfull. 1. Its quicker than getting AE to make a TX. 2. Ignoring AE I think its going to work out cheaper than asking the likes of Sowter (the winder isn't VAT registered, so thats a saving), and the worst reason, is I am trying to duplicate a commercial amp (Yes I know its a silly thing to do, but there you go), and that uses a toroidal mains TX. But I am trying to undercut the £15k a pair price tag.

The other reason, is so far with my crap mains supply here, I have had more luck with toroids than EI transformers not suffering from buzzing.

And there is pleany of scope for buzzing with this, what with 350ma of B+ and 14A of heater supply.

Its all Andrew I's fault. After hearing what his 6c33c amp did in the way of bass, I want to see if its possible to do that bass and add a bit of top end to the mix as well. (I hope this doesn't offend Andrew).
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#4

Post by simon »

Pretty good reasons. I'm trying to spur myself on to order some 5k c cores from AE so I can build 45 and 6EM7 amps. Then I wonder about getting some from Ask Jan First and not waiting 6 months. And then I think I would only want to try the AEs anyway so why bother with the AJF...

An interesting project Nick, there was something really funky about Andrew's bass at Witham. Do you have a link to the commercial amp you're duplicating?
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#5

Post by Nick »

http://stereophile.com/tubepoweramps/1004lamm/

I hope I ahve learnt enough from the 300b supply to make a good go at teh regulator. I use what is in effect half a 6c33c as the regulator element in the phone stage (6c41p).

And as I said at doncaster, I have this idea that regulated supplies are better matches to valves with lower Ra's. So its not that important to a 45, and not that bad with a 2a3, it starts to become worth the effort with a 300b. And a 6c33c has a Ra of the order of 180R so it may make a big difference.

I heard a real one several years ago and was impressed, so we will see :-).
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#6

Post by simon »

Looking forward to hearing them at the next Egg. :D
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#7

Post by Andrew »

Hi Nick,

So is the second 6c33c a shunt or series reg?

Did the shunt you were going to have a go at work?

I expect the low Ra means that winding a good OPT should be easy-ish job as it can have a low winding ratio.

I've been busy measuring my Slagle based LCRs', well at least one of them, I can post the xls if you're willing to host it?

I also tried the currect sources on the 300B's much quieter but the jury's out on the results otherwise, I'm tempted to get some decent hum buckers and have another go at AC.

cheers,

-- Andrew
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Nick
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#8

Post by Nick »

I am guessing that its a series, given the valve lineup of a VR and small pentode, sounds like a classic series to me.

If you want to send the xlf I will post it on the site for you.

I went back to AC on the 300b a bit ago to check, ignoring the hum, it didn't sound any worst that the current reg. But to me it didn't sound any better either.

And no, I never got the shunt working as I wanted it too. Beyond me at the moment. it was the A2 element that was the biggest problem.
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#9

Post by Andrew »

Yes, you could be right about the AC, my system's been out of action since it was packed up for my arborted trip to Owston, so I'm really going from memory.

I still need to try 300v on the driver, 250's not really enough, I thought originally I was running out of steam on the 300B but that's not the case.

I've got some MOSFETs handy for a CCS and I've wired some bases for 6N30's as shunts whilst I waited for bits to arrive for the phono and a couple of 1uF Russians for a boost on the choke input. I'll see where that takes me.

cheers,

-- Andrew
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#10

Post by Nick »

Well I am almost ready to start this now. I will post a thread in the projects when I get some circuits to talk about.

I have the torroids now, and they look nice, how they actually are I can't say yet, but I think that if people have a project that will fit a torroid then Terry is a good place to ask.

I also have a nice quad of Svetlana 6c33c's not sure if they are any better that the normal Ulyanov. But we will see. Thay came is very sturdy cardboard boxes with spec sheets and sealed in plastic bags.

I am going to do my best to be neat with this build (ok not of course to Steve's standard), but I have some copper plates on order for them. Impressed you are I think :-).

Actually part of the desire for neatness is becase some of the high current involved scares me more than high voltage. 7a at 12v, and 300ma at 360v has the potential to make a big bang.

(Ok Darren, I know I need to think about 833 heaters :-)).
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#11

Post by Darren »

I was just lucky to find my heater supplies.

Would have been a bit more difficult otherwise. :D
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#12

Post by Andrew »

I see Mr Keywood has got his hands on a triode trawler amp for review in this months HFW; he certainly doesn't slate it, so more power to your elbow Nick for giving this a go.

I reckon if you can get the treble half as good a Mr I got the bass at Witham you're onto a winner!

cheers,

-- Andrew
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