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Old 20th October 2009, 07:05 PM   #11
jerluwoo is offline jerluwoo  United States
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Anyone else notice that the amp linked http://densen.dk/B-350/Stereoplay%206-04.pdf uses a single IC per side, has to be class D for that much output.
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Old 20th October 2009, 09:43 PM   #12
tiefbassuebertr is offline tiefbassuebertr  Germany
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Originally Posted by Lumba Ogir View Post
be tremendously suspicious about amps that measure good. They don`t ever sound good.
Kurt von Kubik:
I do not really agree to that.
If you look at music, it contains even order harmonics, and none what so ever uneven.
Uneven harmonic distortions, has simply nothing to do with music, therefor the uneven are the most mallicious ones. In addition it is mostly the lower order uneven harmonics, which are these closest to the basic tone, that are the worst ones. But I do think higher order unevens are uneasy to the ears as well.
Lumba Ogir:
If the standard measurements are performed (THD at 1KHz, sometimes at 10 KHz) is exactly this statement also my opinion. Would be selected for the THD measuring the frequency 100 kHz sine wave and for the IM-distortion the values 199/200 KHz (unfortunately, even today still not the standart) then all amplifier that measure good would be automatically sound good.

Kurt von Kubik: What means "Uneven harmonic distortions"? My scandinavian English is very bad. Perhaps you mean "odd harmonics" like third harmonics.
Some years ago I think the same about the odd harmonic low order components as you mentioned today. After I have heard and measure different circlotron power amplifiers (Graaf GM-20 and some diy projects) I don't think so, because there were mainly H3 to observe, both in the measurement as well as in the p-spice simulation. But the perceived sonic quality was (not only for me) at very high level and I was very surprised about this. Previously I had still assumed, that low order odd harmonic distortions causes very worse sound but now I am shure, that worse sound it is caused only by very high order THD components, what means at the same time low order intermodulation products. In this case the follow article about THD spectrum through global NFB is certainly of interest:

What dramatic effect can have a (not optimal) compensation has to be seen on my simulation results by
The wanted schematic I need to know more about Densen's DMCD circuit topology. It is hard to believe, that this is a Class-D (PWM/PCM) variation, as mentioned from diyAudio member jerluwoo

Last edited by tiefbassuebertr; 20th October 2009 at 09:51 PM.
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Old 20th October 2009, 09:57 PM   #13
Cobra2 is offline Cobra2  Norway
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What to do with an old Densen...

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Old 20th October 2009, 10:07 PM   #14
jacco vermeulen is offline jacco vermeulen  Netherlands
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Originally Posted by jerluwoo View Post
Anyone else notice a single IC per side
Anyone else notice that the B-350 uses the exact same aluminium tension bar as the B-300 and the B-320, plus also the multitude of parallel emitter resistors for the output devices ?
Why does it hurt when I Pee ? (Ay Ay Ay https://www.youtube.com/watch?v=w5fLGWrHouk)
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Old 21st October 2009, 05:12 AM   #15
jerluwoo is offline jerluwoo  United States
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Claimed 294 watts into 4ohms from a single IC with those smallish heatsinks seams to be alot for a typical AB/B amplifier. I can not read the language the article is written in though, just see the specs they give. Maybe they have a fancy trick or it has switching rails or something. Still big claims for a single IC.
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Old 21st October 2009, 06:10 AM   #16
ostripper is offline ostripper  United States
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has to be class D for that much output.
The stk - 4048 II http://www.audiolabga.com/pdf/STK4048II.pdf ..can do 150w - 8R and might do 200+w @ 4R if properly heatsinked. The 4050 can do 200w/8 & 300+w/4. I have heard the 4048 in a big fisher and it can not hold a candle to a discreet OPS. The larger PS in the denson might improve on this.

Looking at the schema above , it is just a doug self based amp with 2 pair complimentary BJT outputs .

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Old 21st October 2009, 06:20 AM   #17
GK is offline GK  Australia
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That Densen amplifier is a load of junk designed by a bunch of bunyips. If you own one, drop it into the outdoor dunny and do a big #2 on it.
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Old 21st October 2009, 07:47 AM   #18
Hurtig is offline Hurtig  Denmark
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Densen use 2SC2922 and 2SA1216. http://www.sanken-ele.co.jp/en/prod/...f/2sc2922e.pdf
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Old 21st October 2009, 09:42 AM   #19
oyoyoy is offline oyoyoy
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they dont sound so good in my opinion
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Old 21st October 2009, 10:34 AM   #20
Kurt von Kubik is offline Kurt von Kubik  Denmark
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I┤ve seen measurements on B350 according to IEC, where it runs to hot @ 4 Ohms.
At a time it was claimed to be 250/125 Watts in 4/8 Ohms and the first 40 watts should be class A, and they did not even state the impedance of theclass A power.
It was not class A of course, Densen even lost a lawsuit filed on someone who punked Thomas Sillesen for stating false data. The data proved false naturally, and he lost his case completely.
If looked upon, the data measured by the german magazine, makes it look like if the designed is actually flawed or something wird.
But that is much the way idiosyncratic design is done. You se to that distortion is high, and then call it something fancy. At Densen it is called "Airguitar factor", at Linn it is called "tunedem", and I think Naim calls it "rytm" or so. Linn and Naim though would not bring a product to market with data as measured on the B350. They have different ways of enhancing what they want their customers to be focused at.
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