Krell KSA 100 type amplifier - Page 11 - diyAudio
Go Back   Home > Forums > Amplifiers > Solid State

Solid State Talk all about solid state amplification.

Please consider donating to help us continue to serve you.

Ads on/off / Custom Title / More PMs / More album space / Advanced printing & mass image saving
Reply
 
Thread Tools Search this Thread
Old 10th October 2002, 02:00 PM   #101
diyAudio Member
 
traderbam's Avatar
 
Join Date: Jan 2002
Location: Earth
Hi Ragil,
Someone posted a schematic at the start of this thread somewhere, but I'm not convinced it is an accurate schematic. I do not know where you can find any others.
I remember reading an article in HFNRR 1985(?) - an interview with Dan D'Agostino. He revealled that the KSA50 was a low feedback design - flat 14dB gain margin out to >70kHz with about 50kHz input resistance. D'Ag claimed the design could be run in open loop but that they added some negative feedback to improve stability. If you check out the Krell website you'll find some more info. Like all great designs the Krell probably looks very simple on paper and like all great designs there is a lot more to it that the schematic doesn't show.

The fact that Krell uses a fully balanced, class A design supports the low feedback idea. Their basic approach is to make the circuit as linear as possible. Using double input LTPs will reduce distortion and improve PSRR if (and only if) the two halves behave identically. Getting this right is hard and IMO is not an easy thing to grapple with if you are building your first amp. But the idea of having a flat OL response and having low or no feedback helps to achieve a good sound fairly easily.
  Reply With Quote
Old 10th October 2002, 06:04 PM   #102
The one and only
 
Nelson Pass's Avatar
 
Join Date: Mar 2001
There was nothing extra to the KSA50 that the
schematic doesn't show. It is what it is.
  Reply With Quote
Old 10th October 2002, 07:28 PM   #103
diyAudio Member
 
traderbam's Avatar
 
Join Date: Jan 2002
Location: Earth
Hey Nelson,
Krell being one of you primary competitors (I assume), I assume you've you have done considerably more research than I have. Can you confirm that the posted schematic is accurate?
My comment about the schematic not telling all is an indirect way of saying that the way the transistors are chosen (beyond just part numbers) and the way the performance is measured is not shown. In my experience this is crucial. I do not believe that someone can build a Krell based on the schematic and have it sound anything like as good as Krell build them without a lot of prior experience.
I presume this would be the same for someone building a Pass amp without the benefit of this forum. Is it not the knowledge of part choice (like Vgs threshold matching) and wiring and psu design and many other things that makes an X1000 sound as good as it costs? Which means it must sound very good indeed.
  Reply With Quote
Old 10th October 2002, 08:19 PM   #104
Banned
 
Join Date: Dec 2001
Location: Zamboanga, City of Flowers, Mindanao
Send a message via Yahoo to Elso Kwak
Lightbulb Schematic Krell

Hi Traderbam,
The secret is in the schematic and in the matching of the transistors; especially the inputtransistors.
I own a Gas Ampzilla. The Son of Ampzilla has roughly the same topology as the Krell KSA-100 and that is a very good sounding amplifier too.
Denis I don't consider the complementary input differential stage stupid. To get the best sound the four transistors have to be matched all four. And the electrolytic in the feedback path to get a 1x gain at DC preventing offset gives a much better sound most notably in the bass than a DC-servo with a IC. You can improve it by bypassing the electrolytic with a polypropylene capacitor. Interestingly some IC's have the same schematic as some poweramplifiers.
I can build a Krell, Ampzilla or Son of Ampzilla that sounds better than the original.
  Reply With Quote
Old 10th October 2002, 08:35 PM   #105
The one and only
 
Nelson Pass's Avatar
 
Join Date: Mar 2001
At the risk of shattering any illusions, anyone who
does a workmanlike job assembling these amplifiers
from schematics will get much the same results.

Matching input devices is nice, but depending on what
you are looking for you can get even better results by
substituting devices into a live circuit and evaluating them
in situ. This is a tedious process, but is truly the one that
milks the last bit of performance out of the circuit.

The simpler the circuit, the better this works.

The KSA50 is a nice clean simple Class A amplifier, and that's
why I regard it as the best of the Krells. Don't bother to
flame me if you disagree....
  Reply With Quote
Old 10th October 2002, 08:53 PM   #106
diyAudio Member
 
Tube_Dude's Avatar
 
Join Date: Mar 2002
Location: Aveiro-Portugal
Yes Nelson..

Im with you...some people think that amplifiers work in a magical way...but they work in a cientific way.

If anibody make a amplifier with the same schematic,the same parts...and the some grounding tecnics...it will end up with a similar sounding amp...be it made by you.by me or by Krell!

Audio is engenearing...not mistic or black magic!

Cheers

Jorge Santos
  Reply With Quote
Old 11th October 2002, 05:53 AM   #107
diyAudio Member
 
dhengkoel's Avatar
 
Join Date: Nov 2001
Location: CIA
Quote:
Originally posted by traderbam
Hi Ragil,
Someone posted a schematic at the start of this thread somewhere, but I'm not convinced it is an accurate schematic. I do not know where you can find any others.
Thanks Traderbam,

But that's KSA-100 ... I want to see the KSA-50 schematic, that sound better than KSA-100 ...

I agree with Nelson:
Quote:
Originally posted by Nelson Pass

The simpler the circuit, the better this works.

The KSA50 is a nice clean simple Class A amplifier, and that's
why I regard it as the best of the Krells. Don't bother to
flame me if you disagree....
My interest as DIYer's is how to maximize the minimalist ...... I never clone the schematic as is, I always try to change the transistor and the value of the resistor or capacitor as I calculate myself or take suggestion from this forum ...

Thanks all ...

... & Regards:
ragil.hastomo
__________________
:: The last but not least ::
  Reply With Quote
Old 11th October 2002, 09:35 AM   #108
diyAudio Member
 
traderbam's Avatar
 
Join Date: Jan 2002
Location: Earth
Jorge said: "Audio is engenearing...not mistic or black magic!"

Well that is true. However, I have encountered two classic problems among audiophiles and engineers alike. One is indeed to think that "the reason for something sounding better than than the rest is some form of magic or black art and is therefore unknowable through engineering" and the other is to think that "if standard engineering principles are applied then it is possible to make a duplicate that will sound as good because there is no hocus-pocus involved"

Well I can report from personl experience that neither of these views is correct. The former is born out of ignorance - what I like to call the "corn circle" belief system: I don't understand it therefore it is magic (or aliens). The second view is born out of ignorance and lack of listening experience. In fact it is usually espoused by engineers who listen with their eyes. The problem here is that too limited an engineering theory is applied to assess the design and therefore the conclusion is that the design can be duplicated from the schematic - or, more commonly, a denial that sonic differences exist or are controllable. I could call this the "it should sound this way so it does and if you don't think it does then you are deaf" phenomena.

I have learned from this that I should open my ears and then open my mind, in that order.

BAM

"Don't bother to flame me if you disagree...."
Spoil-sport.
  Reply With Quote
Old 11th October 2002, 11:51 AM   #109
Account Disabled
 
Join Date: Sep 2002
Default Another idea

Hi,

Maybe this spanish design can be something to evaluate or is it just bull.... check this image comments is welcome.

The power transistors is MJL 21193 and 21194 are they good for high end and the topolgy I have never seen things like this can this work ??
Attached Images
File Type: jpg power.jpg (18.7 KB, 1376 views)
  Reply With Quote
Old 11th October 2002, 12:22 PM   #110
diyAudio Member
 
dhengkoel's Avatar
 
Join Date: Nov 2001
Location: CIA
That's remind me to class H QSC amplifier ... ... is that correct ???

Regards:
ragil.hastomo
Attached Images
File Type: jpg qsc-1100.jpg (86.7 KB, 2746 views)
__________________
:: The last but not least ::
  Reply With Quote

Reply


Hide this!Advertise here!
Thread Tools Search this Thread
Search this Thread:

Advanced Search

Posting Rules
You may not post new threads
You may not post replies
You may not post attachments
You may not edit your posts

BB code is On
Smilies are On
[IMG] code is On
HTML code is Off
Trackbacks are Off
Pingbacks are Off
Refbacks are Off


Similar Threads
Thread Thread Starter Forum Replies Last Post
KRELL KSA Amplifier series mods Dr.H Solid State 10 28th January 2013 12:22 PM
KRELL KSA300S Amplifier wilfredo Solid State 8 18th September 2007 05:05 AM
Type 46 as voltage amplifier abj1 Tubes / Valves 6 29th January 2005 05:34 AM
Seek Krell power amplifier schematic blueman Solid State 2 12th December 2002 02:31 AM


New To Site? Need Help?

All times are GMT. The time now is 01:41 PM.


vBulletin Optimisation provided by vB Optimise (Pro) - vBulletin Mods & Addons Copyright © 2014 DragonByte Technologies Ltd.
Copyright 1999-2014 diyAudio

Content Relevant URLs by vBSEO 3.3.2