No - feedback amplifier

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"The End mkII" DC amp

"The End mkII" ready ...a superfine sounding amp with 3281/1302 and Tip 41/42C
Overall: L.H. Clausen was right..... http://www.tubeamp.hobbysider.dk/
Faster and bettter drivers tried....not worth it! The better specs do not deliver better sound! ....there's a lot of "torgue" in the Tip 41c and Tip 42 drivers. "crab"? hmm.....
Following OP's tried 3281/1302 , 5200/1943, 2922/1216....the last with only one pair. Conclusion: use 3281/1302 ...cheap and strong.

The irritating part is that The End mk3 version needs close matched input transistors....but great sound then!!...it was essential with close cobberlines on the mkII PCB to keep the recommended transistor mounting.(heat balance). DO NOT add DC to the RCA input terminals = burned four outputs and drivers!
Super sound amplifiers.
 
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Well I'm sure it will sound good.
Technically, it isn't a no-feedback design - there's lots of local feedback / degeneration; has to be to get good sound.
But it certainly is a non-GLOBAL-feedback amp.

jan didden

Yes, the right topic in the headline should read: Power Amp with local serial feedback and without global NFB. Maybe the moderators is able to perform a correction in the headline.
Please let me know follow regarded the schematic in post #1:
1) How is to calculate the voltage gain factor?
2) which commercial power amp device uses this topology
3) which commercial power amp device is configurable between this topology (i. e. without global NFB) and with global NFB ?

Thank you for your advices.

check out in this case also this thread:
http://www.diyaudio.com/forums/soli...-nfb-negative-feedback-me-wrong-question.html
 
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We don't want to see your mind all boggled and stuff do we now...

I suspect there are some reasons why people think sans fdbk is better. Apart from the usual witchcraft that pervades this hobby.

a) distortions are different (measurably higher) and some like this sound
b) for square law devices I believe it was derived mathematically that feedback makes distortion profile worse unless enough feedback is used. Perhaps tube amplifiers with 3/2 law devices fall into this category.
c) I have found that the compensation needed to make a feedback amplifier stable has a profound effect on the sound. I'm talking Cdom here.
d) Interaction between amplifier and load is different with fdbk
 
For me only B is true. Ok also D, but mostly applies to woofer or complex passive speaker loads.

There is also the woodoo of the signal fed back to the input that sounds wrong from my logic POV, but I have amps with GNFB that sounds good too, so I'm not sure what I really prefer.
 
This deserves a separate answer.

I don't really know enough to answer in much depth, but my observations tell me that the compensation has a clear affect on the sound.

Compensation is needed with -ve feedback. Compensation affects the sound. Therefore, -ve feedback affects the sound. It's one way of looking at it.
 
Further, we need to examine why ngfb/compensation why affects the sonics.

If you believe that this is nonsense, then the clear conclusion is that ngfb is the best solution and there is no conundrum. Most feel this is the correct conclusion, often based on studies of THD.

If you think that ngfb does degrade the sound (or the lag compensation as Bigun posits) you come to magic $64k question. Why do changes of lag compensation affect this sound, and by any non-metric, such as subjective listening, are you correctly hearing your ears?

You choose one school or the other, and the choice is definitive, opening out one of the biggest issues in audio. And if you believe non-ngfb improves the sound, you are on a limb.......

Hugh
 
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This is an interesting comparison. The 3281/1302 are my favourite output transistors... If you can get all pairs of the 2922/1216, it would be worth trying them again.

Cheers

I noticed "The End" thread here.
I have all pairs of the 2922/1216, but the PCB layout of the mk.2 version do not allow two pairs per channel.
In the mk.3 version mr. L.H. Clausen do not recommend two pairs per channel because of oscillation risk. He recommend instead one add-on output PCB with a pair of 2922/1216 and then the possibility of biamping. Mr. Clausen took the view, that the amplifier outputs were "stiff" enough with one set of output transistors and about 120-140W sine/ one channel.

rgds.
 
MKIII - SanKens

I noticed "The End" thread here.
I have all pairs of the 2922/1216, but the PCB layout of the mk.2 version do not allow two pairs per channel.
In the mk.3 version mr. L.H. Clausen do not recommend two pairs per channel because of oscillation risk. He recommend instead one add-on output PCB with a pair of 2922/1216 and then the possibility of biamping. Mr. Clausen took the view, that the amplifier outputs were "stiff" enough with one set of output transistors and about 120-140W sine/ one channel.

rgds.

@ Leakstereo20

I see on This Page that this Guy made beautifully exactly the the version MKIII as You describe.
There isn't any comments about Sound but the finished modules looks excellent and ready for bi-amping as You point out.
It would be interesting to hear some impressions about how the finished amplifier sounds . .

Regards
 
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@ Leakstereo20

I see on This Page that this Guy made beautifully exactly the the version MKIII as You describe.
There isn't any comments about Sound but the finished modules looks excellent and ready for bi-amping as You point out.
It would be interesting to hear some impressions about how the finished amplifier sounds . .

Regards

Hi Smiley,

I am the guy who has build more than 12 different "The End" amplifiers since 1989. The MK I, MK II and MK 3 version. The pictures you found on my Picasa VBKOLSEN site is the MK 3 version with RingEmitter Transistors from Sanken.
The MK 3's sounds just beautiful on my AR3a Improved speakers without any form for agressive tweeter- midrange sound .....silk top , very defined voice and piano midrange and a precise, clean thunder- bottom bass reproduction.

To test the quality of the amplifier we used the JBL XPL160 and XPL200 with the problematic titanium midrange and titanium tweeter. Standard amplifiers sounds agressive and hissing on the mentioned speakers while Audio Research and similar quality amplifiers gets the finetuned sound out of the XPL160/200.

JBL4412 , 4311B and L96 has been tested as well with great dynamics and no irritating spikes .....which normally occurs with cheaper amplifiers on the JBL monitors.

Find at least two "The End" amplifiers on my amateur site and links to larger construction pictures at Picasa VBKOLSEN.

If you have a little patience I am about to translate the whole MK.3 construction manual. Double PSU a.m..

Best rgds.
 
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It was the only BJT amp that I could accept... The bass was more like mosfet amps than bjt ones... I was shocked that a bjt amp could sound that good :D

Another friend who, like me, found the philosopher's stone:)

There are not that much difference between "The End mk.II" and "The End mk.3" version in sound reproduction. The Toshiba 2SC3281/2SA1302 OP's has a strong point in the mk.II version, sounding very close to the mk.3 version.

Rgds.
 
Jay said:
It was the only BJT amp that I could accept... The bass was more like mosfet amps than bjt ones... I was shocked that a bjt amp could sound that good

@ Jay

As You say, this is really hard to believe but such a nice surprises are really rare these days and are very ''WELCOME''.

Hi Smiley,

I am the guy who has build more than 12 different "The End" amplifiers since 1989. The MK I, MK II and MK 3 version.

If you have a little patience I am about to translate the whole MK.3 construction manual. Double PSU a.m..

Best rgds.


@ Leakstereo20

I was really impressed visiting Yours site and see there all the beautiful work & rework on Yous Speakers and not to mention all the amplifiers (vintage) all the beauties inc. the the new ones . . . speechless, I can just say VOW to all Yours great work You made.
The sound You describe about MKIII amp is really excellent and I do search for the same one (not sub_ppm THD) for quite a while.
I would gladly wait for You to finish MK.3 construction manual.
My wish is to try to make this amp and taste the sound You already enjoy. :)

Nice regards,

Andreas
 
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Joined 2011
@ Leakstereo20

I was really impressed visiting Yours site and see there all the beautiful work & rework on Yous Speakers and not to mention all the amplifiers (vintage) all the beauties inc. the the new ones . . . speechless, I can just say VOW to all Yours great work You made.
The sound You describe about MKIII amp is really excellent and I do search for the same one (not sub_ppm THD) for quite a while.
I would gladly wait for You to finish MK.3 construction manual.
My wish is to try to make this amp and taste the sound You already enjoy. :)

Nice regards,

Andreas

Hi Andreas,
Yes, I have made some amplifiers during the last three decades , and the idea with my amateur site is just free exchange of ideas and help to other hifi interested people like myself. Sometimes one can't solve a problem...then it's nice to get some clues and tips. My first valveamp with motor-boating before the internet could give me some answers, was not that fun!:)

I am on page 6 out of 14 pages with the translation. It takes quite some time. The manual for "The End MK 3.1" and "Millennium" was never translated to English in Denmark as far as I know.

I need to get permission from L.C.Audio before I upload the 14 construction pages to Picasa web and VBKOLSEN. :)

See you

Rgds.
Kim
 
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