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Old 15th November 2012, 03:45 AM   #7591
Pano is offline Pano  United States
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Quote:
Originally Posted by a.wayne View Post
Choirs have away of separating the wheat from the chaff , not to speak of the 10 amp fuses letting go ... ..
Yes indeed they do. Choirs are very hard to do.
Sustained loud passages call for a robust power supply.
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Old 15th November 2012, 08:14 AM   #7592
dvv is offline dvv  Serbia
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Originally Posted by Pano View Post
Sustained peaks? Aren't those called plateaus?

I've been looking back in the thread to see how much output voltage DVV is aiming for, I'll find it.
My speakers have to fill with sound a room of some 110 sq.ft., i.e. small. They are nominally 8 Ohms, minimum 6.5 Ohms, worst case phase shift is -25 degrees, effciciency is 92 dB/2.83V/1m.

My speaker cables are van den Hul Hybrid 352. That's a mix of silver plated OFC cable, mixed with carbon fibre (vdH has been a professor of metallurgy at a Dutch university for 40 years now). Cable has 2 x 256 strands and is capable of passing through well over 200 Amps.

My current range of readily available amps consists of cheap'n'cheerful low level (a bit above absolute entry level) 2x50W to very much High End 2x180W amps, from Toshiba, Marantz, Sansui, Harman/Kardon and Karan Acoustics ( http://www.karanacoustics.com ).

The point is not to go watt mad, I already have more watts available than I know what to do with. The point is twofold:

1. It has to be mine, I have to design and make it, for the hell of it, and
2. As John put it so aptly, it has to be done right.

At this time, I have a simulator working model which will nominally deliver 28.3 Vrms into 8, 4 and 2 Ohms, with minimal voltage loss, on a continuous basis. It will not clip up to around 175 W/8 Ohms, due to relatively high voltage lines, +/-63 regulated for everything including predrivers and drivers, and +/-56V for the output trannies alone. There should be two versions.

One should use 3 pairs of Motorola/ON Semi MJ 21195/21196 (metal can TO-3 trannies, rated at 250W each, 15 Arms, 30 Apeak, Ft > 4 MHz).

The other should use 4 pairs of Motorola/ON Semi MJL 3281/1302 (platic pack TO3, rated at 200W each, 15 Arms, 30Apeak, Ft > 30 MHz).

The two versions have a double purpose. One is to check out for myself a theory I have, which is that in many cases, older power devices, developed over decades, actually sound just as good and often better than the new(er) ones, even if their spec sheet says different. I have a nagging feeling that older power devices appear to be more stable than the new ones, and I want to check it out.

The other is to produce two solid power amps, which I can then use to biamp my speakers. If it turns out as well as I hope it will, perhaps a third unit later for the wife, who currently has a Harman/Kardon 680 integrated powering her JBL Ti600 floorstanders.

That's it in a nutshell. No binding peconceptions, my starting point is a fully complementary topology, but I do not insist on it.

The only thing I do insist on is fully electronic protection against overvoltage, overcurrent, overheating and excess DC. I do not trust fuses alone, I've seen far too many burnt out amps with "protection" fuses intact. I believe the fastest fuse we have is one made up of transistors.

That's it.
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Old 15th November 2012, 08:23 AM   #7593
dvv is offline dvv  Serbia
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Originally Posted by Wavebourn View Post
It does not matter. My Pyramid amps have 2x100W output power. It's transformer is for 360W continuous, it is quite different from what you can find in that 7+1 "1000W" amps

In Tower amp I have 3x300W toroids.
Yes, and in the last few years, the Chinese have come up with "PMPO", or "Peak Modulated Power Output". That's a magic formula which enables their say desktop PC speakers, fed from a teeny meeny 20W outboard power supply to enable them to deliver literally hundreds, and sometimes even thousands, of watts.

Tesla must be turning in his grave.

I am thinking either about one 1 kVA toroid, with separate secondaries for left and right, or two 500 VA toroids.
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Old 15th November 2012, 11:02 AM   #7594
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When I was 14 I remember taking music power calculations to my science teacher Mrs Grundy . She convinced me that peak current x peak voltage the only meaningful calculation . As far as I know she had never considered the problem before . You should have seen her . The blackboard was covered in maths just like a spy film and she was on a voyage of her own . I asked how she could be so confident ? She had worked on radar during the war and it reminded her of similar things . She drove an orange VW Beatle . She was way beyond eccentric . I remember congratulating her on my grades , she said she had asked for me to be marked down due to my extreme laziness . I wasn't allowed to go on BBC Young scientists of the year as my hair was down to my waist ( I suspect other reasons also ) . I didn't mind as it was an embarrassing project . Still liked her , DF 96 are you she ?
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Old 15th November 2012, 01:54 PM   #7595
DF96 is offline DF96  England
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Originally Posted by nigel pearson
Still liked her , DF 96 are you she ?
Many people have said many strange things about me, but I have never before been suspected of being an ancient female schoolteacher. Each part of that is wrong: I am not quite ancient (although not far off), I am definitely male and I have never been a schoolteacher.

It is for others to judge whether I am eccentric. I do like maths and I do like truth - perhaps nowadays that makes me eccentric.
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Old 15th November 2012, 02:08 PM   #7596
dvv is offline dvv  Serbia
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Originally Posted by DF96 View Post
Many people have said many strange things about me, but I have never before been suspected of being an ancient female schoolteacher. Each part of that is wrong: I am not quite ancient (although not far off), I am definitely male and I have never been a schoolteacher.

It is for others to judge whether I am eccentric. I do like maths and I do like truth - perhaps nowadays that makes me eccentric.
Unfortunately for all of us, it does.

Disclaimer:
I do NOT think of you as eccentric, just precise, and I respect precise.
I do NOT think of you as an auncient female schoolteacher, or even just a teacher, at all.

Just for the record.
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Old 15th November 2012, 02:10 PM   #7597
dvv is offline dvv  Serbia
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Originally Posted by Wavebourn View Post
It does not matter. My Pyramid amps have 2x100W output power. It's transformer is for 360W continuous, it is quite different from what you can find in that 7+1 "1000W" amps

In Tower amp I have 3x300W toroids.
Only 3 300W toroids?

I expected at least three Chernobyls.
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Old 15th November 2012, 11:43 PM   #7598
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Originally Posted by dvv View Post
Only 3 300W toroids?

I expected at least three Chernobyls.
It was the previous one. The last one was never finished, it stays in the corner waiting for the winter.
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Old 16th November 2012, 07:16 AM   #7599
dvv is offline dvv  Serbia
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Originally Posted by Wavebourn View Post
It was the previous one. The last one was never finished, it stays in the corner waiting for the winter.
Winter? Really?

Do such bad things happen in the promised land of California?

But seriously, I really cannot imagine winter in California. Somehow, after so many movies from Hollywood, we who haven't been to California imagine it in a perpetual summer. "Winter" seems like just a little less summer.

Do you EVER have any snow, even if transient?
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Old 16th November 2012, 08:18 AM   #7600
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Originally Posted by DF96 View Post
Many people have said many strange things about me, but I have never before been suspected of being an ancient female schoolteacher. Each part of that is wrong: I am not quite ancient (although not far off), I am definitely male and I have never been a schoolteacher.

It is for others to judge whether I am eccentric. I do like maths and I do like truth - perhaps nowadays that makes me eccentric.
Sorry about my strange and sincere compliment . Of people I have taken notice of you and she start to fill the fingers of one hand .

Thanks for polynomial distortion fact . I work around it as best can and with greater success since you said it . Truth , I say fiction is the only truth . It often contains truth and makes no pretense of being the truth . Liking the truth makes you eccentric ? That seems to have the ring of truth about it ?

Nigel
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