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Old 2nd November 2004, 08:21 AM   #51
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Hi janusz,

I can recommend the standard Antrim transformers from HARBUCH. I've used many of them and never had a problem. All my amps are dead quiet. They have hundreds in stock and a great selection. For example there is 3 25-0-25 160VA to choose from.

There are options to have a SAFETY SCREEN and/or ELECTROSTATIC SCREEN at extra cost and are a custom wind but I've only been tempted and haven't seen the need to worry. I think that's what his "special" design may be.

I visit them in person and do get a "funny" feeling each time I visit, must be because I only get 2 or 3 at a time. I've asked to have a look around and was given an unenthusiastic brief tour. They are good quality and cheap and I have gotten a discount a couple of times.

You have to remember they probably only make <$15 per toriod so having to pack, post and do the paper work for two separately would be a PITA.

Just in case you haven't seen their web site.
http://ourworld.compuserve.com/homep...ch/harbuch.htm

Yeah, the folks at Harbuch are nearly the exact opposite to Hugh. Maybe Hugh should sell them?

BTW: The only toriod I have that hums is one I got from Jaycar. At the time I thought that was normal.

Thanks
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Old 2nd November 2004, 11:02 AM   #52
quasi is offline quasi  Australia
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Default These toroids

Hey Janusz

The harcbuch toroids sit quite closely to my PA amp modules and I don't have a problem with noise.

I think the placement of the secondaries in the case is probably more important. Under heavy current draw they generate a bit of a field themselves.

Anyway I remember when I bought mine (ages ago) they didn't really know what to do with me because I walked in and asked them what they had (I hadn't really decided on the exact volts or VA then). But I walked out with the two 625VA's put them in my luggage and flew home (Adelaide). I think the airline staff were surprised how much small luggage could weigh.

It probably makes a difference if your there in person, you can just take them with you without fuss.

The only mod I made was overwind extra secondaries for my +/- 15 volts for other circuitry.

Cheers

PS. The board design for this amp is in the error checking stage.
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Old 3rd November 2004, 11:48 AM   #53
quasi is offline quasi  Australia
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Default Draft Layout

Aah here 'tis.

The board measures 222mm x 65mm and includes on-board DC detect with relay.

I'll send photos of a built prototype later.

Cheers
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Old 3rd November 2004, 06:35 PM   #54
AndrewT is offline AndrewT  Scotland
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Hi, the thirteen diyers who downloaded quasi's zip file.
How did you open it?
XNview did not understand it.
regards Andrew T.
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Old 4th November 2004, 02:03 AM   #55
quasi is offline quasi  Australia
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Default You need Winzip

Hey AndrewT

You can download Winzip from;


Cheershttp://www.winzip.com/downwz.htm
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Old 4th November 2004, 02:24 AM   #56
janusz is offline janusz  Australia
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Default HARBUCH toroids

Thanks Grege, Aksa and Quasi for your comments.

Consequently, I have decided to take two toroids as was my original intention. I think I have ordered these toroids (yesterday, I provided Peter with my card details, address etc) but as you have explained to me it looks I have to wait for the heavenly decison. It would have been much easier if I lived close by and could pop in and get them over the counter. Sometimes I feel as if Perth was located at the end of the world - and at the wrong end for that matter.
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Old 4th November 2004, 03:18 AM   #57
jwb is offline jwb  United States
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Hi. There's no point in zipping a JPEG, it doesn't save any space (you saved only 4% in this example). I'll repost the bare JPEG as a service to the readers.

Congratulations on your own original design.
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Old 4th November 2004, 11:25 AM   #58
quasi is offline quasi  Australia
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The board layout that I posted a couple of days ago and reposted by JWB has some errors. These have been corrected but I won't post it again until it has been built and tested.

Cheers
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Old 4th November 2004, 05:18 PM   #59
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I have had a similar experience with Antrim but I would be reluctant to use a large VA model (with loss losses) in an amplifier to be dead silent.

The last special they did for me of 1KVA that groaned like an old lady in my Pass Aleph 2 and I had to get rid of it. I called them about it and was fed a pile of crap about my mains quality to getv rid of me denying a problem with the design.(all my other transformers from them make no noise). The design was specified specifically for audio and I got quite the opposite.

I then called them back a week later under an assumed name and was told they don't make transformers specifically for audio.

It would appear they are mass market and won't enter the risk of making silent transformers like Pilitron (as used with hi end manufacturers in the USA like Passlabs).

The problem is the core size and the amount of copper. For low noise you need to use a much larger core size which costs money.

Ian
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Old 5th November 2004, 11:55 AM   #60
quasi is offline quasi  Australia
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Default The making of the board part 1 - Exposing

A pair of layouts is exposed onto pre-sensitized board. I use a spray-on positive photoresist called POSITIV 20. Friends of mine in Germany bought some for me and sent it to Australia. I couldn't find it here ...but it's great stuff. Made by CRC industries.

cheers
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