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Old 17th May 2012, 06:08 PM   #5611
SY is offline SY  United States
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Yeah, I think you're right- the earlier ones had complementary outputs but not inputs.
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Old 17th May 2012, 08:20 PM   #5612
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Quote:
Originally Posted by john curl View Post
Nigel, a minor point. Jim Bongiorno was not first with complementary differential topology. Dan Meyer, of Southwest Technical products was the first to 'advertise' the circuit topology in 'The Audio Amateur', for example. However, both John Iverson and I had independently developed it in 1968, and we were both designing amps with the topology. John I. for Electro Research or the equivalent back in the late 60's, and me for Ampex and Alembic. We did NOT learn it from Jim B. Jim is a good designer, in any case.
Er, ... not Nigel, he is completely innocent, I was the one who said it. And I still remember where I got that from - W. Marshall Leach's first amp project published in "Audio". '75, or '76, something like that.

To be fair, Prof Leach did say that this was "as far as he was aware", and mentioned J.B. in context of a Dynaco amp circa 1971.

John, I would never call that "a minor point". Nobody is arguing, but as a fan of history, I do like my facts to be right.

For me, a great update - thank you.
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Old 17th May 2012, 08:48 PM   #5613
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I live in Belgium and in my house I have bi-phase, so I think as an audiophile I should be glad
The 230 vac is made of 2 phases of 133 vac.
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Old 18th May 2012, 12:54 AM   #5614
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Originally Posted by Pano View Post
Welcome to the world of active crossovers! They can be quite startling when you first hear them - they do a lot of things right.

I think active crossovers shine because, in part, they are so much easier to get right. Great passive crossovers are a b**** to design. It can be done, it's just harder. Active crossover offer a world of tweaks and possibilities.
Just spent the evening listening to my new setup, and it's gorgeous even without any tuning to speak of. Just looking at the specs of the speakers, and it seems I independently homed in on the same crossover frequency that the passive crossover was set at.

The overall impression is of the music smoothly pouring out of the space in front of me, as opposed to it being forced under pressure out of two boxes. Much less tiring for the ears.
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Old 18th May 2012, 02:03 AM   #5615
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Originally Posted by Pano View Post
Welcome to the world of active crossovers! They can be quite startling when you first hear them - they do a lot of things right.

I think active crossovers shine because, in part, they are so much easier to get right. Great passive crossovers are a b**** to design. It can be done, it's just harder. Active crossover offer a world of tweaks and possibilities.
I can see both theoretical and practical differences engineering-wise between active and passive, and every such difference is a positive for active. I recall asking earlier in this very thread why active systems aren't more popular among high-end audiophiles, but as usual, I forgot that it's not always about getting the best possible sound reproduction. So much money spent, and so much less than optimum results...
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Old 18th May 2012, 06:44 AM   #5616
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Originally Posted by benb View Post
I can see both theoretical and practical differences engineering-wise between active and passive, and every such difference is a positive for active. I recall asking earlier in this very thread why active systems aren't more popular among high-end audiophiles, but as usual, I forgot that it's not always about getting the best possible sound reproduction. So much money spent, and so much less than optimum results...
... but so good for a failing industry.

In my view, and in the most general terms, the audio industry stopped being about good and better sound in the early 80ies, when it was first hit by the new fad, video. A few years later, both audio and video were hit hard by the stll newer "gadget", the PC.

Sales slumped, then slumped hard, and ever since then we have had an interminable slew of snake oil vendours appearing and a steady demise of many proud names, such as Sansui, Akai, JVC, etc, etc.

Generally, it has stopped being about better sound and has become all about shifting as many boxes as you can. Anything for a sale. Quality now lives on the fringes of the audio industry, residing in small upstart companies mostly (but not exclusively) which need to be heard of, so they try hard. Most of the rest is run off the mill production.
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Old 18th May 2012, 08:33 AM   #5617
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Originally Posted by danny_66 View Post
I live in Belgium and in my house I have bi-phase, so I think as an audiophile I should be glad
The 230 vac is made of 2 phases of 133 vac.
Thanks Danny .

I measured 95 - 0 - 95 at 213 Chausee de Lille Tournai ( Dornik ) . I reported it to an electrician friend . He said although very bad it was not illegal ( before harmonization ) . You have it well above the stated 253 V . I did a survey of world electricity for my boss and produced for him a device which kept everything to +/ - 6% of 230 V at 4000 VA . It was rejected . I now learn it has been accepted because someone listened to it . I was told +/- 2% or forget it . I said that mine is only 0.5 dB out if the amplifier has no regulator . The house in Belgium had the most beautiful switch gear I ever saw in a house . Sorry to say the first thing I inspect is the incoming supply . I even have photos of Cuban instantiation ( US /USSR ) . On first inspection the Cuban system looks bad . It is not . It is just untidy .

Although not as fastidious as John and D V V ( which I observe and respect ) I find being told +/- 6% when 156 to 270 V is typical where it was designed to work a slight ridicule of my design ability .

If anyone is missing the point here . Bad electricity = bad sound . However balanced supply is so good we can ignore a little naughtiness ( 190 to 266 V ) . You will need special transformers to take it out of saturation if the noise bothers you or losing power .

Why Americans don't take advantage of their balanced supply is beyond me . Some even have the luxury of not having to share a transformer to the house . All they need do is balance the usage in the house . If you have the choice 100 000 VA to your house is good . I have 92 000 VA limited to 23 600 VA . Realistically it isn't that due to me not using 100 A fuse and 0 ohms cables . I am saying the potential in terms of impedance is useful .

I think my photo of Cuba says more than the usual long political diatribe . I wished I had some Motorola horns when I went there to put in the speakers ( and a hand full of resistors and capacitors ) . Chinese Motorola clones are $2 . Salsa is great . However it requires a minimum standard of sound quality to work it's magic . Cuba is great if asking . I wanted to meet the musicians , alas the ones I wanted to meet were already no more . I watched the most fantastic program on Euclid whilst there on TV . The Spanish was very easy to follow on that program . It took about 4 hours and if you didn't get the idea one way they tried others . I found a mic cable under my bed . However it was broken . I suspect it was used in the past . I had no secrets so didn't care . If this is typical I can see why our Russian engineer Vladimir is so well trained .

Last edited by nigel pearson; 18th May 2012 at 08:56 AM.
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Old 18th May 2012, 09:15 AM   #5618
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Quote:
Originally Posted by john curl View Post
Nigel, a minor point. Jim Bongiorno was not first with complementary differential topology. Dan Meyer, of Southwest Technical products was the first to 'advertise' the circuit topology in 'The Audio Amateur', for example. However, both John Iverson and I had independently developed it in 1968, and we were both designing amps with the topology. John I. for Electro Research or the equivalent back in the late 60's, and me for Ampex and Alembic. We did NOT learn it from Jim B. Jim is a good designer, in any case.
The only complimentary system I ever looked at was from Rotel . As it was stolen from them ( I found out later ) I never tried it . I have JB's number given to me years ago . I never phoned him, There is a Jean Hiraga circuit I halfheartedly tried . I didn't have the JFET's so used bipolar . I gave up and unfairly thought the JFET's not essential to tying the idea . It did all the oscilloscope stuff it should have .

In tubes I have always thought about how to make a P type tube . Perhaps with a semiconductor collection electrode where the anode of the N type would be . Unlikely it would work .

My greatest regret is never having made a " me " type simple op amp . I tried a few times but wasn't satisfied . It should be easy as many components essential to common day op amps can be left out as big components are not a problem . A simple yet wonderful discrete op amp thread would be interesting . I think it should have no more than 10 active components and equal or better OPA 604 . GBP of 20 MHz and < 2 nV noise . +/- 30 V would be ideal .
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Old 18th May 2012, 09:34 AM   #5619
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Hello Nigel,
The electricity entering in my house is actual 3 phase, each phase is 133vac.
Two of those phases are then distributed in my house and that gives me exactly 230 vac at the outlets.
Grts,
Danny
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Old 18th May 2012, 09:40 AM   #5620
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Thanks Danny and it goes in my dossier . Enjoy this music . This was the man I was to meet . I am an honorary prof of maths in Cuba . I never accepted it . The guy I was supposed to write to never wrote back ! I had written binomial theorem on a piece of paper and a cleaner found it !!!!

http://www.youtube.com/watch?v=hVKE6ewPrY4

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Last edited by nigel pearson; 18th May 2012 at 10:05 AM.
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