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Old 10th August 2005, 04:59 PM   #501
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Rajeev,

A typical hand wound transformer has an efficiency of 80-90% so with 10% to 20% losses, you might need to go higher than 1:1.5.

People who use Autotansformers (or impedance matching transformers) experience a loss in damping or uncontrolled bass, but they sometimes like the bloom of the midrange. They also experience attenuation of the HF. Basically unless you experiment with it, you will not know if you like the sound or not, it's a toss.
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Old 10th August 2005, 05:10 PM   #502
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Quote:
Originally posted by rajeev luthra
I am planning of using a autotransformer in the output of the amp with a ratio of 1; 1.5
The other day my mind drifted and i mentioned MacIntosh amplifiers, solid states with output transformers, discussing Arif's mystery Pioneer amplifier.
The 2 Mac models i had the chance of hearing when they were produced long time ago did not sound half bad to me.
Like Arif said, depends on the quality of the transformer.
Power in is power out minus losses, so with voltage out 50% higher current through the output devices will be at least 50 % higher too.
You'd have to check if they'll handle that much, and how big the transformers would be with the kind of power you are talking about and still have good frequency response.
A bonus of using a transformer would be the added protection of the output stage.
You are the winding expert, with what i've seen you do so far it would not surprise me if you were able to make a good output transformer, Rajeev.
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Old 14th August 2005, 05:13 AM   #503
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Dear Arif & Jacco,
An old leaflet of MacIntosh amplifiers in which the company described

their output transformer with winding diagrams was very useful in

designing my custom made output transformers , I can hardly make out if

there is a transformer in the output , the sound is so good . The advantage

to use a auto transformer is that the transformers power handeling is only

that of the power it is increasing hence the size is much smaller . yes the

devices will handle the extra current I checked that first .
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Old 14th August 2005, 12:27 PM   #504
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I hope it sounds as good as you hope with all the hard work you put into it,

cheers!
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Old 15th August 2005, 03:25 AM   #505
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THANKS for the encouragement !!!

Please let me have your comments on post no 267 by Villaw here

Leach clone, pretty good looking

rpage=10&pagenumber=27

very interesting
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Old 15th August 2005, 03:26 AM   #506
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http://www.diyaudio.com/forums/show...readid=46824&pe rpage=10&pagenumber=27
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Old 16th August 2005, 04:55 PM   #507
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I am posting this picture for you to show that DIYers can also make good audio transformers , we have to make number of bifilar windings and add them for minimum losses , the same could have also been made with a single thick wire but with more losses .
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File Type: jpg cnv0012.jpg (72.4 KB, 990 views)
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Old 24th August 2005, 01:12 PM   #508
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Rajeev:

Would you please be so kind as to educate me on why bifilar (or trifilar) windings are sometimes needed.

I mean, do the bifilar windings behave just like one winding, with twice the wire thickness?
Do they behave like two separate inductors in parallel, so half the copper resistance, half the inductance?
Do they behave like two coupled inductors, energy from one gets coupled into the other, then reflected back, then reflected, etc...

Each time I thinks about all the possible ways to treat a bifilar, it's like thinking about infinity, it makes my head spin.

thanks
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Old 7th September 2005, 03:44 PM   #509
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Dear Funberry,
Sorry to reply so late ,
some of the advantages of bifilar windings are that ;- 1, the length wire

in two windings will be the same hence the resistance will also be the

same and due to this if there is any voltage drop that will also be the

same , thus making two identical windings .
2, In audio transformers to get minimum losses , it is desirable to get

max signal transfer from one winding to another , for this the windings

should be very close to one another , now if we use several parellel

bifilar windings they will have better signal transfer than only two

primary and secondary windings
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Old 21st September 2006, 02:52 AM   #510
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Default Phase 400 Series 1 Trannies?

Anyone out there have any advise for my rebuilding of my PL400 Series One.
It has ben suggested to me that I replace replace everyone of the 12 power trannies, originally PL909's (some burnt) with MJ15024 or 2199XX or 150XX.
I feel the MJ15024 might be good, but I'm really not sure about any possibility at this point. Any advice from any one out there on any of these choices?
Frank Marsi
frankmarsi@verizon.net
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