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Old 13th March 2012, 05:54 PM   #3351
a.wayne is offline a.wayne  United States
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Sounds like that "size doesn't matter " argument


I have small dynamic speakers , I think they call them headphones and from personal experience regardless of speaker size and efficiency, a big un amplifier most times sound better than a small un..

My mini monitors sound their best when on the Vk 500 , sounded good on other smaller powered amplifiers , but nothing like when it had the power reserves of the bigger BAT. We hooked the BAT to a pr of CLS and it sounded like it had 2 watts..

I don't like the sound of Adcoms, yet I keep at least a pr around at all times , why ? they drive anything for testing purposes and you can't beat the price...
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Old 13th March 2012, 06:03 PM   #3352
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Hi,

Quote:
Originally Posted by a.wayne View Post
Sounds like that "size doesn't matter " argument
It doesn't.

On my latest speaker design the 16 Watt from a 300B (yes, you CAN get 16W from a 300B) are awesome in a 100m^2 room... As for the other one, size doesn't matter for anyone with big 'un, right?

Quote:
Originally Posted by a.wayne View Post
I have small dynamic speakers
I have big ones only. I just do not "get" small speakers, even less most 'cans. My current pair at home does do splendid with a 35 Watt non-NFB Tube Amp which does not double into halve impedance, instead it quarters.

I also have a pretty big solid state one here (160W/250W rated), it does worse in all that matters and either Amp is way loud enough...

Ciao T
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Old 13th March 2012, 06:06 PM   #3353
a.wayne is offline a.wayne  United States
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Yang Wang size room , bad SS amp ....
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Old 13th March 2012, 06:09 PM   #3354
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I was there at the beginning of the Citation XX project. I, in fact, approved Matti Otala's coming to the USA to design amps and preamps. We had worked together, before, and this was a chance to do something really right. It was 1978.

The first design put forth by Matti Otala was all bipolar, based on a complementary video amp sort of design. Very good, by the way, fast and high current. My assignment was to make a 'bullet proof' tracking dual supply for the amp that would supply lots of current (not 200A, however) and be SOTA. I got started at my lab in California, and regularly visited HK as the need arose. I built a virtually 'bullet proof' dual linear tracking supply that actually tripped the 30 amp building breaker, rather than self-destruct with a direct short across it. Everything seemed OK. However, politics was in the wind, and apparently Matti did not like me sharing the 'limelight'.

What he did was take me aside and ask me to put out a bit of extra time and effort on the power supply, in order to speed up the development. I was, at the time, on 1/2 time or about 25 hours/week, so I had the time available, so I did it. However, when my billing changed, and I requested payment for twice the hours that I normally did, the S--- hit the fan! I felt bad that I did not 'cover myself' by asking my immediate supervisors first, but I presumed that Matti Otala would cover me, since it was at his request that I did the extra work. Well, he didn't, and they terminated me immediately, with annoyance. Nothing I could say would clear me, they thought I had overstepped my contract. Yup, Matti 'hung me out to dry'. Kind of sad, except I was offered a new proposition to have my own corporation: JC Audio Designs, by a Japanese investor. I just went on to found that company (another story entirely).

What about the aftermath? Well it took years for the Citation Amp to be built, and it was unrecognizable from its beginnings, but I was not shown the schematic. I saw that they had decided NOT to use a regulated power supply, that they had pretty good performance, and the amp had the unprecedented retail cost of $5000. When I saw it at CES, I mentioned to Matti that I, too, had made a new power amp for VMPS, called the 4Q-2, a 250W balanced bridge amp with 2A Iq (64W), regulated supply, and 3 air-blown heatsinks, and it was just down the hall. When I asked Matti, WHY the amp was so costly, he said it was partially because he used gold plated circuit boards.
Oh well, however decades later, I found that Matti Otala had ripped me off, taking MY complementary differential jfet input stage and using it instead of his original design, without telling me. I will never completely forgive him for that.

So he got me removed from my job as consultant at HK, AND he took my circuit topology (that I always knew was better than his), what a guy!
Over the decades, we remained distant colleagues. I was never brought in for another paper, etc. and we would say hello, if we met on occasion. Still, for all his political infighting, he really taught me a lot over the decades.
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Old 13th March 2012, 06:32 PM   #3355
dvv is offline dvv  Serbia
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Quote:
Originally Posted by a.wayne View Post
Interesting , never heard of the XX ....
Surprisingly enough, a LOT of people well into the field never have.

At the time, HK gear was built in Japan, by a company called Shin Shirasuna and Silver. It seems HK and they had a falling out because Silver started selling identical units, with identical design and components, but under their name.

Like the 72x series, specifically. I remember being shocked at the sameness when I saw their ad in an Italian magazine, a few pages after an HK ad. IDENTICAL!

It appears this cut short not only their business association, but also the production of the XX series. Hence, very few were made, they sold like hot cupcakes, and anyone owning them would rather die then part with them.

But it did start a completely new approach to power in HK. After the XX series, everything was different, HK was launched int an orbit of rather large impulse power capabilities, something they still hold very dear and near to heart to this day.

Check out their Signature 1.5 model. Its voltage amplification part looks a lot like Marantz's, but instead of two pairs of output trannies, there are six pairs. You can bet your cotton socks that output stage can deliver a LOT of actual, real world current when required.

@Thorsten

T., for decades I've trying to take a look under the hood, i.e. at its service manual. If you have any knowledge of where one might find it, I would be much obliged if you'd let me know, here or as a PM.
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Old 13th March 2012, 06:38 PM   #3356
dvv is offline dvv  Serbia
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Wayne, with a peak output current of 200 A, it not only doubles down, it goes way beyond that.

When you halve the load impedance, an amp may still be able to deliver the same nominal output voltage, but NOT with the same THD and IM specs.

More of this anon, in VERY practical terms. Stay tuned.
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Old 13th March 2012, 06:39 PM   #3357
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DVV, I don't think that many here will really understand what happened in those days (30 years ago) between HK and Silver. I have been to both factories, and Silver virtually took over.
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Old 13th March 2012, 06:42 PM   #3358
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DVV, you can NEVER completely duplicate the maximum drive voltage between 8 ohms and 4 ohms. You just have to leave some room by providing slightly more
power supply voltage than is absolutely necessary.
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Old 13th March 2012, 06:45 PM   #3359
bcarso is offline bcarso  United States
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Quote:
Originally Posted by ThorstenL View Post
Hi,

Citation XX/XXP was introduced in 1980. There where only a few made and probably more sold in Japan than in the US. Design was in part Matti Ottala. I read somewhere that the thick film hybrid driver stage came directly from Finland for HK...

Ciao T
Yep, that's consistent with the shutdown of Andy's program in February of 1990, when I joined Harman as an employee.

So many programs there were started and shut down after spending tons of money. One guy in the professional group had the moniker "Vice President of Cancelled Programs"


Brad
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Old 13th March 2012, 06:47 PM   #3360
bcarso is offline bcarso  United States
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Quote:
Originally Posted by john curl View Post
DVV, I don't think that many here will really understand what happened in those days (30 years ago) between HK and Silver. I have been to both factories, and Silver virtually took over.
Marty Zanfino could tell us, if it pleased him to do so.
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