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Old 16th December 2009, 02:53 PM   #31
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BV,
as stated, measurements say nothing. For me the perceived sound that counts, since my approach is not commercial, I don`t need to prove anything to anybody. I meant linearity according to the ear`s own scale (quite different from artificial made-up scales).
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Old 16th December 2009, 03:57 PM   #32
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Quote:
Originally Posted by Lumba Ogir View Post
BV,
as stated, measurements say nothing. For me the perceived sound that counts, since my approach is not commercial, I don`t need to prove anything to anybody. I meant linearity according to the ear`s own scale (quite different from artificial made-up scales).
So the japanese manufacturers build their parts according to someones or yours 'ear scale'?
Do Toshiba or Sanken do their quality control by listening?
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Old 16th December 2009, 04:02 PM   #33
BV is offline BV  Slovakia
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Lumba, if You preferred "rich, warm, musical..." sound (with high level of low order distortion and IMD product) , it is OK, it is Your taste.. But then please talk not about technical facts as linearity and technology of "switching" devices, and especially not about "linearity according to the ear`s own scale" .
PMA had made on our local forum test, he posted recording with various levels of low order added distortion (without information what he made) . Even "golden ears" cannot hear and tell what is diference between tracks, and distortion levels was about 1% and more .
You are right in one point, measurements say nothing, but only about personal preferences. They can tell quite all about objective performance , off course not single 1kHz THD+N measurement.
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Old 16th December 2009, 05:09 PM   #34
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Quote:
Originally Posted by Lumba Ogir View Post
BV,
as stated, measurements say nothing
In case of the traditional measuring methodes (THD 1000 Hz, IM 19/20KHz) you are right.

But with the appropriate measurements, I would get a fairly accurate statement about the amp sound character without having heard him oneself.

Unfortunately, it is so, that nobody uses such measuring methods. Or even so that nobody wants to use such methods of measurement. Thus, discussion like this are still present by this forum, but also in others.

An easy way to find out an exactly attestation regarded different sonic quality (and different distortion measurement) through different ft's and different emitter structures would be to create a ordinary complementary push pull darlington power follower without front end for voltage gain in the NFB loop, so that only the NFB through the follower topology itself have an effect (open loop gain not too high). The schematic by the Densen-thread here about
Densen amp
is a good topology therefore, if one remove the first stage of power buffer (please ignore the second schematic version).
The test must perform by two modes: pure Class-A and Class AB (20-50mA through the output devices).

Perhaps one of the members can perform and investigate this.

I recall a similar test report, where the old 2N3055 has been compared with modern parts of power devices (perhaps JLH-ClassA?) Unfortunately I have forget the download place in the web.
Attached Files
File Type: pdf C ...-A-Densen Topol. orig-mod.ckt.pdf (25.1 KB, 307 views)

Last edited by tiefbassuebertr; 16th December 2009 at 05:14 PM.
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Old 16th December 2009, 05:13 PM   #35
AndrewT is offline AndrewT  Scotland
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Originally Posted by wg_ski View Post
And you don't "need" a triple at the more-normal 200W level anymore.
I have shown a few times why I can't agree with that statement.
It's down to peak current delivery into reactive loads.

200W into 4r0 (within your limits of +-55Vdc) requires Vpk = 40Vpk and Ipk = 10Apk.

Into 4 ohm speaker load this demand can rise to around 30Apk.
This cannot be met from a two stage output EF not even with double complementary pairs in the final stage.

The peak current demand for 200W into 8ohms is not nearly as difficult to meet but it is way outside your +-55Vdc supply rail limit.
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Old 16th December 2009, 05:20 PM   #36
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Juergen,
Quote:
So the japanese manufacturers build their parts according to someones or yours 'ear scale'?
They don`t. Moreover, data sheets specifications do not signify sonic properties, but 80MHz is more promising than 4MHz. The general bandwidth / linearity relationship is known. Ultimately, a practical evaluation will tell, that can be done easily and reliably, no musical skills, no golden ears, all you need is a change in attitude.
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Old 16th December 2009, 05:27 PM   #37
wahab is offline wahab  Algeria
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Quote:
Originally Posted by AndrewT View Post
I have shown a few times why I can't agree with that statement.
It's down to peak current delivery into reactive loads.

200W into 4r0 (within your limits of +-55Vdc) requires Vpk = 40Vpk and Ipk = 10Apk.

Into 4 ohm speaker load this demand can rise to around 30Apk.
This cannot be met from a two stage output EF not even with double complementary pairs in the final stage.

The peak current demand for 200W into 8ohms is not nearly as difficult to meet but it is way outside your +-55Vdc supply rail limit.
it s quite doable...i use darlingtons MP1620/MN2488 with a beta of 6500 mini
at 7 A, and they are the second grade ,the first being 15000 mini....
using four in paralele, wich is a minimum for an amp.
loaded with 4R, it can provide the 30 amps with 4.6 mA of
total base current and 2 mA , respectively for the second and first
grades...
all is question of choice of components...sure that if you
use the classical beasts as the onsemi mjl + mje , it will fall short..
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Old 16th December 2009, 05:28 PM   #38
AndrewT is offline AndrewT  Scotland
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I recall Sanken doing a 60MHz device, but not a complementary pair.
I also think ONsemi are doing 45 to 50MHz devices.

Is there a reason why the performance should be much different when built into a real circuit designed to suit these devices.
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Old 16th December 2009, 05:31 PM   #39
AndrewT is offline AndrewT  Scotland
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Quote:
Originally Posted by wahab View Post
it s quite doable...i use darlingtons MP1620/MN2488 with a beta of 6500 mini
at 7 A,
I have not even bothered to look at the datasheet, but I will guarantee that this integrated Darlington will not perform as a well as a pair of Darlington connected discrete BJTs, over a range of realistic output currents.
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Old 16th December 2009, 05:33 PM   #40
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Quote:
Originally Posted by AndrewT View Post
I have shown a few times why I can't agree with that statement.
It's down to peak current delivery into reactive loads.

200W into 4r0 (within your limits of +-55Vdc) requires Vpk = 40Vpk and Ipk = 10Apk.

Into 4 ohm speaker load this demand can rise to around 30Apk.
This cannot be met from a two stage output EF not even with double complementary pairs in the final stage.

The peak current demand for 200W into 8ohms is not nearly as difficult to meet but it is way outside your +-55Vdc supply rail limit.
The right approach for this you will find in this topology of Dynacord's stage power amp L-1600 resp. EV (Electro Voice) P2000 (still available) go to Owner's Manual for datas
http://www.electrovoice.com/documents/ev/p2000-eds.pdf
and the attachements (some schematics)
Attached Files
File Type: pdf L1600 Power Buffer bridged.pdf (130.1 KB, 270 views)
File Type: pdf L1600 Power Supply 85244.pdf (35.8 KB, 176 views)
File Type: pdf L1600 VA Stage 86207I-p2.pdf (187.7 KB, 233 views)
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