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Old 28th September 2004, 02:43 PM   #1
jogas is offline jogas  Italy
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Default Any experience with this nice toroidal OT?

HI,
I found on the internet the amplimo site and among the many available transfo I found this interesting one

http://www.amplimo.nl/download/3a524.pdf

It is unexpensive but it is the less performant of the whole available pool.
Does anybody have experience or suggestions?
Are the bandwitdth values "enough"?

Thanks in advance
Giuseppe
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Old 28th September 2004, 03:12 PM   #2
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Others may disagree with me but I don't think the specs are very good.
I'm concerned with the frequency response which was measured at a power level of 1 mW.
The primary capacitance is 1.79 nF. That's a lot of capacitance. I'm also concerned that the -3dB power bandwidth (assuming 40 watts) only goes down to 27 Hz. If the output is down 3dB at 27 Hz, the transformer won't have a really good low frequency response below about 60 Hz.
Also ... look at the phase shift at 20 kHz. It's almost -60 degrees.

I'd pass on this one. I'd like to hear what others have to say.
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Old 29th September 2004, 01:56 PM   #3
igormak is offline igormak  Russian Federation
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Hi,

I did not try exactly this OT, but I ordered and tested Plitron
PAT4002. Both from Vander Veen, anyway. Sure the same
iron. Results was very bad, you'll nothing hear below 200Hz at all. High frqs very good >200kGz. Sounds very bad and durty.

I broke one "famous" OT. The reason in Economy. Economy of Fe and Cu.

Igor.
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Old 29th September 2004, 02:04 PM   #4
jogas is offline jogas  Italy
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Thanks for your answers.

Surfing the web I found this other trasfo that shoeul be much better...

http://www.shinrock.com/Audio_Transf...4.3k_0.95.html

what do you think about it?
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Old 29th September 2004, 05:38 PM   #5
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Quote:
Originally posted by igormak
I did not try exactly this OT, but I ordered and tested Plitron
PAT4002.
The Amplio OPTS & the Plitrons are the same, made by Plitron, designed by Meeno van der Veen.

I was lucky to sit in on a hearty discussion between Meeno & Bill Perkins (PEARL) about the merits of these. Bill was championing C-Cores. A lot of what was discussed was over my head, but both these guys know A LOT about transformers.

The big issue with the toroids is that they can't handle DC very well, and invariably in an OPT (unless parafeed) you will have DC.

Personally if i had serious money to spend i'd be looking at the Lundahls.

dave
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Old 30th September 2004, 07:27 AM   #6
igormak is offline igormak  Russian Federation
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Quote:
Originally posted by planet10


The big issue with the toroids is that they can't handle DC very well, and invariably in an OPT (unless parafeed) you will have DC.

Personally if i had serious money to spend i'd be looking at the Lundahls.

dave
Hi Dave,
Yes, tors likes DC less than EI do. They have other advantages anyway. Here is the skill of engineer how to use tors.
With correct winding and right core problem decisionable.

Simply, Plitron doesn't count their OT properly. VanderVeen answered me on my letter with "your output stage not right balanced". So, they use DC as just a gost.

Now I wind tors only myself and think real DIYer have to do it himself. It's not too complicated really, IMO.

Igor.
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