| 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.
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. |
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| Nelson Pass |
There was nothing extra to the KSA50 that the
schematic doesn't show. It is what it is. |
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| traderbam |
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. ;) |
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| Elso Kwak |
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. ;) |
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| Nelson Pass |
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.... |
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| Tube_Dude |
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 :drink:
Jorge Santos |
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| dhengkoel |
| 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.
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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
:) |
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| traderbam |
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. ;) |
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| leiade |
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 ??:) |
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| dhengkoel |
That's remind me to class H QSC amplifier ... :confused: ... is that correct ???
Regards:
ragil.hastomo |
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| leiade |
It is a Spanish RAM PA amplifier and I see that nothing in this world is as it appears to be.
Every kind of electrotech designs is very often built upon others "own" design and maybe patents so... why is the Krell schematics secrets it must be a part of the consumers right to know what his product consists of especially if it is broken and the only way is to ship it across the big see.;) |
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| Peter Daniel |
| quote: | Originally posted by Tube_Dude
some people think that amplifiers work in a magical way...but they work in a scientific way.
If anybody makes a amplifier with the same schematic, the same parts...and the some grounding technics...it will end up with a similar sounding amp...be it made by you, by me or by Krell!
Audio is engineering...not mistic or black magic!
|
To some extent this is correct. But when you want to go further and improve the basic engineering and extract maximum potential from a design the materials that were used for building the amp and the way they interact with each other play tremendous role. I can take two exact circuit boards with exactly the same PS and put them in two different enclosures and I will have two different sounding amps. My recent experiments proved that.;)
And don't forget that when you place those amps on two different supporting platforms, they would also sound different. Even the feet change the sound.
To me it really is more like black magic and I will go as far as saying that it is as important as engineering.;) |
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| Tube_Dude |
Hei Peter Daniel...
I'm looking forward for a thread in this forum named: The sound of the enclosures!!!
I must add that i really apreciate your contribution for this forum and your sense of humor!
Cheers :drink:
Jorge Santos |
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| leiade |
Enclosure! Thats the "secrets"about the Krell and Pass amplifiers, they use very good enclosures, even the oldies like the ksa100 and Nelsons Treshold series uses very good and robust enclosures.
If you going to build an amplifier try make get the best but... do not buy the enclosure just build it.
The high tech machine shop can make a very good high end enclosure for your amp.
They use high tech cutting machines and the cost of material is very cheap use stainless steel, this material need no after treatment just simple polish helps to hold the costs down.
Aluminium is a little more expensive as it need anodizing.;) |
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| leiade |
I got an idea, is it anybody out there who can make pro drawings with computer CAD software if so this forum can construct an enclosure that hold very high standard same as the high end industry just make it with international measures.
The art of making an enclosure is not a thing just for Krell,Pass and Co.
I repeat it is cheapier than you think.
An example make the faceplate thick say 10 mm and the rest af enclosure parts 5mm.;) |
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| traderbam |
When designing an enclosure don't forget that...
Mechanical rigidity is a good thing for electronic circuits.
Sheilding circuits from external RF noise is a good thing.
Ferrous metals (iron/steel) conduct magnetic fields.
Non-ferrous, conductive metals (Al, Cu) reflect magnetic fields.
Non-ferrous, non-conductive materials (wood, plastic) are invisible to magnetic fields. |
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| leiade |
I think that you can find nonmagnetic stainless steel but Al is also very handy to use as you can anodizie it and get a very attractive surface.
And when you cut the enclosure parts it is also very easy to make any hole with high precision and this is very important for the stability and it also make it easier to assemble.;)
So if any can make an example and saving it as dfx, it may be useful for any amateur to begin with and even make changes to the basic drawing in a cheapier software as the AutoSketch.:) |
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| leiade |
It would be better to use nonmagnetic stainless steel as the shielding of the enclosure would be much better as the anodizing Al enclosure parts is isolated very hard to make any good contact between the different parts ofcourse it would be better to make the enclosure of one or two pieces but the enclosure wouldn't be so versatile to use, the idea is to make one or two standard drawings that can be used either as an preamp/buffer and power amp enclosure.
The assembling structure must be very rigid and straightforward. :) |
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| Audiofanatic |
| quote: | Originally posted by webercarbmann
Hi again
The scematics i have are not werry good. I will have to make a better version using protel. By the way, i also have a scematics for a PAM 3 preamp. I will try to post them in a near future. Please be patient. Would some of you be interested in some KMA 100 PCB`s ??
Peter;) |
Hi Peter,
I'm looking (for more than 4 years)for the schematics of the PAM-1 and PAM-3, Would you be so kind, as to post the schematic of the PAM-3 (and if you have the 1 also)?
Thanks in advance.
Audiofanatic
;) |
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| Upupa Epops |
| Do somebody know who is author of this design ? I like, in oposity of Peter, complicated circuity ;) - my last PA have 40 transistors in one channel ( only PA, without protection circuity and input amp ) :cool: . P.S. : And have overall negative feedback :D . |
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| Drioannis |
| Can anyone please send me the ML23.5 and 27.5 schematics at drioannis@yahoo.com(a lot of space)?Thanks |
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| Drioannis |
| Wish I had the 3xx series schematics... |
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| Audiofanatic |
| quote: | Originally posted by Drioannis
Wish I had the 3xx series schematics... |
Sorry to tell but I had the amp and didn't like it, it sounds boring and not musical, I don't know how to say this, but it's one of the worst sounding amp's I've listen to in my audiophile life.
Why do you want or need the schematic?
I fixed a 331 without a schematic but it was a real pain in the but.
I rather have a Plinius SA-50 or a cheaper Atoll AM-100 than this piece of metal that produce sound. I hope I didn't step on a few feets, but it's just my terrible experiance with ML amps.
BTW I made a AB test with a original 331 and the one I had, and the one I had was modifid by me and sounded much better than the original one, but still to slow and life less.
Just my 2 cents (I appologize to every one that disagree with me)
All the best,
Audiofanatic ;)
P.S. I don't have the schematic I just did reverse engeneering but don't have it anymore. |
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| Drioannis |
| No problem.You have the right to tell your opinion and I take it in consideration |
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| mbosko |
Any news for PAM - 3 schematic ?
Thanks |
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| vosjulian |
Can anybody give me the schematic of the powersupply from a mark levinson no 23?
There are a few components burned.
thanks a lot.
Julian Vos
vosjulian@hotmail.com |
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| corbelli |
I need the schematics or service manual of a Krell KSA300S.
my e-mail: bunker@ono.com
Thanks in advance. |
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| umut1001 |
| moved the question about ksa100.. |
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| Hifi101 |
Can anybody give me the schematic of the powersupply from a mark levinson no 23.5?
There are a few components burned.
talkwithscott@juno.com
Thanks |
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