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Old 18th June 2012, 11:37 PM   #6191
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Quote:
Originally Posted by a.wayne View Post
Where can i find these "great " Marantz amplifiers ....
I did not say they are great. They win against those that are more "undersized". To check how "undersized" it is, run all channels and see what fraction of power from all of them simultaneously can be obtained before it goes out of specs, or simply dies in a smoke cloud.
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Old 18th June 2012, 11:38 PM   #6192
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Originally Posted by john curl View Post
Parasound makes amps with varying power supply capacitance. You pay your money, and you get your choice. Usually, I don't happily accept credit for the design, unless at least 15,000 uF caps are used, 12,000 for 5-6 channel amps. More later.
John; what about transformer and heatsinks? Are they upgradable as well, or they are undersized in capacitance department only?
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Old 19th June 2012, 12:05 AM   #6193
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Originally Posted by wahab View Post
Today s standards are , well , not very standardized
I recall how much those late '70s Marantz models cost new.
Four times that amount now (~35 year inflation) buys a much better amp.
Is called progress.
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Old 19th June 2012, 12:46 AM   #6194
a.wayne is offline a.wayne  United States
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Quote:
Originally Posted by john curl View Post
Parasound makes amps with varying power supply capacitance. You pay your money, and you get your choice. Usually, I don't happily accept credit for the design, unless at least 15,000 uF caps are used, 12,000 for 5-6 channel amps. More later.
Examples: 4 X 33,000 / channel JC-1
2 X 33,000 / channel HCA-3500
2 X 15,000 / channel HCA-1200
2 X 6,800 / channel HCA-1000 Bass is somewhat weak, but OK for small system.
Tells me all i need to know ...
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Old 19th June 2012, 06:52 AM   #6195
dvv is offline dvv  Serbia
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Quote:
Originally Posted by jacco vermeulen View Post
Overhere, on a regular basis (usually the local bay)

No disrespect for Marantz, but let's be serious. By today's standards, that stuff is mediocre and outdated.
No disrespect here either, but I find that their last "Designed in the U.S.A., manufactured in Japan" series, 1978-1980, sonically beats the pants off most modern attempts, in their relative class, of course.

Not perfect, of course, but dating back to the quickly fading days when those people REALLY tried on their standard series. Unfortunately, that was the last of Marantz worth mentioning for quite a while after that.

It was the last of the "whole, grand picture" design objective time, after that, it was all about being "analytical", "subtly detailed", etc, and the whole picture, top to bottom, was left out in the cold. The entire concept changed.

Not to even mention the quality of build. By today's standards, their middle of the range model 1152 DC would be classed as top of the range with most manufacturers except for the nominal power.

Take a look at them inside, and you'll see what I mean. Take a look at their schematics and you will be surprised; of course they show their age in some respects, but are surprisingly up-to-date in other aspects.
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Old 19th June 2012, 07:03 AM   #6196
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Originally Posted by Wavebourn View Post
Guys, let me reveal you one secret. "Oversizing" is kind of stupid term invented by ignorant people. Actually, the proper term is "undersizing", against optimal values, in order to cut costs. All sizes above optimum are not worth increasing, so Oversizing is a bad term that means waste of materials (designer's failure, actually).

Undersizing is the result of voluntary consideration of so called "nominal" power that is below clipping level. Who undersizes less (like Marantz, John Curl, etc...) win.
Not to mince wirds here, my Polish cousin, but "oversized" as I use it refers to an average of the day.

In absolute terms, "oversized" would be when you add another cap and nothing happens, because you already had enough. And as far as I am concerned, you have "enough" when your amp can deliver the specified power output into the lowest load you specify it for without any appreciable degradation of the sound. Obviously linked to nominal power output.

Personally, I am wholesale into John's reasoning, although I get there using a different route. When I asked him about what he'd consider a job reasonably well done for a nominal 100/200W amp into 8/4 Ohms, he said 22,000 uF minimum; my calculations told me a total of 32,000 uF was required for what I wanted. That's 32,000 uF per line, per channel, a total of 128,000 uF for a stereo amp.
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Old 19th June 2012, 07:09 AM   #6197
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DNM-designed Capacitors

DNM found many years ago that putting slits in the foil reduced eddy currents . This helps high frequency response . The risk is , in increasing the cap size it also reduces the HF quality . Many have found adding small caps is not the complete answer . Nor is multiple caps as defining the exact star point is then more difficult . Going back to the use of bigger transformers ( more iron ) . Has anyone ever calculated the resonant frequency of a power supply ? I imagine it must be of some significance . One should also look at the 50. 60 , 100,120 Hz input of the rectification . It must have a sonic signature . Perhaps this is why increasing cap size works . It swamps the time signatures ? My tests with this indicated 40 Hz is better . I had by chance a 40 Hz supply . That was the limit , below that the amplifier's transformer was unhappy . This is contrary to expectations , people think a higher frequency better . Specifically the mid range was more open . This was using a big re-generator I built .

Last edited by nigel pearson; 19th June 2012 at 07:31 AM.
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Old 19th June 2012, 07:10 AM   #6198
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Quote:
Originally Posted by jacco vermeulen View Post
I recall how much those late '70s Marantz models cost new.
Four times that amount now (~35 year inflation) buys a much better amp.
Is called progress.
Progress is one of the most misused words of today. That's what they usually call cost cutting.

Please define "a much better amp", I'd really like to know, since I have quite a few vintage and current "High End" amplification (assuming you think of an integrated amp delivering 180/250 W into 8/4 Ohms and costing around € 6,000 as "High End").
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Old 19th June 2012, 07:20 AM   #6199
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Quote:
Originally Posted by dvv View Post
In absolute terms, "oversized" would be when you add another cap and nothing happens, because you already had enough.
Right. Neither cap, transformer, transistors, heatsink. Waste of material if to increase above optimal value, or even undesirable effect when some parasitic parameters increase with added value, like one more pair of output transistors increase capacitive load to driver.

Quote:
And as far as I am concerned, you have "enough" when your amp can deliver the specified power output into the lowest load you specify it for without any appreciable degradation of the sound. Obviously linked to nominal power output.
Right, and nominal power equals to peak power, like in all my power amps.
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Old 19th June 2012, 09:12 AM   #6200
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Quote:
Originally Posted by Wavebourn View Post
Right. Neither cap, transformer, transistors, heatsink. Waste of material if to increase above optimal value, or even undesirable effect when some parasitic parameters increase with added value, like one more pair of output transistors increase capacitive load to driver.

Right, and nominal power equals to peak power, like in all my power amps.
There, you see, Wave, we CAN agree on something! Now, was that so hard?

But seriously, we have touched upon a subject not often mentioned, that of using wrong terms for various ideas. Ever since the marketing departments took over from the engineering people, that effect has been on the rise.

Sometimes, it can be even a bit of fun - for example, calling the rate of signal exchange "slew rate". Damn, I hope my amp isn't drinking secretly so it slews. But we all like abbreviated versions, so "slew rate" is easier than "rate of exchange". Whoever thought of "slew rate" surely had a good sense of humor, and that is (almost) never a bad thing.
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