I've compiled a list of components and parts suppliers I'm going to use. Most resistors are Holco, critical ones Riken, and some of the values not available from Holco are Dale. 5W resistors are Mills and 2W Kiwame.
Electros are Black Gate, NX type for the feedback and Std for the other. 100nF & 100pF are Wima polypropylene, 620pF and 390pF are polystyrene. All except the Dales are available from Parts Connexion in Canada, the Dales are from Welborne Labs.
If anyone is interested I can post the list with all the order codes, prices etc here.
Electros are Black Gate, NX type for the feedback and Std for the other. 100nF & 100pF are Wima polypropylene, 620pF and 390pF are polystyrene. All except the Dales are available from Parts Connexion in Canada, the Dales are from Welborne Labs.
If anyone is interested I can post the list with all the order codes, prices etc here.
Hi all,
Here's the list I mentioned. SOme of the values are a little off-spec but shouldn't be a problem. Quite a few of the choices are based on personal subjectivity, so I'd encourage & appreciate debate using this list as a starting point.
Although more resistors could be 0.25W rated, I played it safe and only used them where there's absolutely no risk even in extreme situations. Some were chosen merely because it was the only brand/wattage/value which came close the specified value/wattage, R125 being an example.
I've chosen the Riken resistors for the most critical ones in the signal & feedback path, but others such as the 100R emitter resistors could also gain from it - it just becomes too expensive and one has to draw the line somewhere.
I couldn't find "brand" resistors of 2R2 0.5W rating for R132-R135, but they're often available as generic 0.5/0.6W metal film types sold in strings of 10.
The C102 & C103 feedback caps should be high quality, I chose the non-polar Black Gate NX. In theory a single 470uF should suffice as they are already non-polar, but once again I decided to stick to the original schematic. I guess two BG Std caps should be almost as good, or Elna Cerafines.
C110 & C111 are BG Std, my experience with Elna Cerafine is that they're not as effective for decoupling - BG or Panasonic FC are more appropriate here.
All the component sizes were checked with the PCB layout, and all fit. Exotic caps (Sonicap/Musicap/Multicap/Theta/Kimber etc.) for the 100nF ones aren't recommended, as they're usually much larger than the footprint, resulting in long lead lengths. A quality 63V Wima FKP or MKP would be enough.
The components from RS were used for countries (such as mine) where local vendors have virtually no stock of quality components, naturally they can be sourced from several local stores in more prosperous countries.
R 101 1k Riken 0.5W $2.40 pcX 62083
R 102 22k1 Holco 0.5W $0.40 pcX 50195
R 103 47k5 Dale 0.5W $0.20 Welborne V4-47.5k
R 104 4k7 Holco 0.25W $0.60 pcX 50026
R 106 4k7 Holco 0.25W $0.60 pcX 50026
R 107 47k5 Dale 0.5W $0.20 Welborne V4-47.5k
R 108 1k55 Holco 0.5W $0.40 pcX 55080
R 109 1k55 Holco 0.5W $0.40 pcX 55080
R 110 9k1 Holco 0.5W $0.40 pcX 50177
R 111 9k1 Holco 0.5W $0.40 pcX 50177
R 112 1k55 Holco 0.5W $0.40 pcX 55080
R 113 1k55 Holco 0.5W $0.40 pcX 55080
R 114 100R Dale 0.5W $0.20 Welborne V4-100
R 115 100R Dale 0.5W $0.20 Welborne V4-100
R 116 1k55 Holco 0.5W $0.40 pcX 55080
R 117 1k55 Holco 0.5W $0.40 pcX 55080
R 118 100R Dale 0.5W $0.20 Welborne V4-100
R 119 100R Dale 0.5W $0.20 Welborne V4-100
R 120 3k32 Dale 0.5W $0.20 Welborne V4-3.32k
R 121 3k32 Dale 0.5W $0.20 Welborne V4-3.32k
R 122 100R Dale 0.5W $0.20 Welborne V4-100
R 123 100R Dale 0.5W $0.20 Welborne V4-100
R 124 4k75 Holco 0.5W $0.40 pcX 50161
R 125 820R Holco 1W $0.50 pcX 62505
R 127 24R Kiwame 2W $1.10 pcX 66145
R 128 24R Kiwame 2W $1.10 pcX 66145
R 129 1k5 Riken 0.5W $2.40 pcX 62085
R 130 22k Riken 0.5W $2.40 pcX 62103
R 131 22k Riken 0.5W $2.40 pcX 62103
R 201 0R5 Mills 5W $1.85 pcX 62700
R 202 0R5 Mills 5W $1.85 pcX 62700
R 203 0R5 Mills 5W $1.85 pcX 62700
R 204 0R5 Mills 5W $1.85 pcX 62700
R 105 5k pot Bourns N/A RS 375-922
R 126 5k pot Bourns N/A RS 375-922
C101 560pF Polystyrene $0.75 pcX 65622
C102 1000uF BG NX 25V $12.95 pcX 60089
C103 1000uF BG NX 25V $12.95 pcX 60089
C104 100nF Polypropylene N/A RS 414-7614
C105 390pF Polystyrene $0.75 pcX 64140
C106 390pF Polystyrene $0.75 pcX 64140
C107 100pF Polypropylene $0.75 Welborne WM1
C108 100pF Polypropylene $0.75 Welborne WM1
C109 100nF Polypropylene N/A RS 414-7614
C110 10uF BG Std 16V $1.20 pcX 58643
C111 10uF BG Std 16V $1.20 pcX 58643
Here's the list I mentioned. SOme of the values are a little off-spec but shouldn't be a problem. Quite a few of the choices are based on personal subjectivity, so I'd encourage & appreciate debate using this list as a starting point.
Although more resistors could be 0.25W rated, I played it safe and only used them where there's absolutely no risk even in extreme situations. Some were chosen merely because it was the only brand/wattage/value which came close the specified value/wattage, R125 being an example.
I've chosen the Riken resistors for the most critical ones in the signal & feedback path, but others such as the 100R emitter resistors could also gain from it - it just becomes too expensive and one has to draw the line somewhere.
I couldn't find "brand" resistors of 2R2 0.5W rating for R132-R135, but they're often available as generic 0.5/0.6W metal film types sold in strings of 10.
The C102 & C103 feedback caps should be high quality, I chose the non-polar Black Gate NX. In theory a single 470uF should suffice as they are already non-polar, but once again I decided to stick to the original schematic. I guess two BG Std caps should be almost as good, or Elna Cerafines.
C110 & C111 are BG Std, my experience with Elna Cerafine is that they're not as effective for decoupling - BG or Panasonic FC are more appropriate here.
All the component sizes were checked with the PCB layout, and all fit. Exotic caps (Sonicap/Musicap/Multicap/Theta/Kimber etc.) for the 100nF ones aren't recommended, as they're usually much larger than the footprint, resulting in long lead lengths. A quality 63V Wima FKP or MKP would be enough.
The components from RS were used for countries (such as mine) where local vendors have virtually no stock of quality components, naturally they can be sourced from several local stores in more prosperous countries.
R 101 1k Riken 0.5W $2.40 pcX 62083
R 102 22k1 Holco 0.5W $0.40 pcX 50195
R 103 47k5 Dale 0.5W $0.20 Welborne V4-47.5k
R 104 4k7 Holco 0.25W $0.60 pcX 50026
R 106 4k7 Holco 0.25W $0.60 pcX 50026
R 107 47k5 Dale 0.5W $0.20 Welborne V4-47.5k
R 108 1k55 Holco 0.5W $0.40 pcX 55080
R 109 1k55 Holco 0.5W $0.40 pcX 55080
R 110 9k1 Holco 0.5W $0.40 pcX 50177
R 111 9k1 Holco 0.5W $0.40 pcX 50177
R 112 1k55 Holco 0.5W $0.40 pcX 55080
R 113 1k55 Holco 0.5W $0.40 pcX 55080
R 114 100R Dale 0.5W $0.20 Welborne V4-100
R 115 100R Dale 0.5W $0.20 Welborne V4-100
R 116 1k55 Holco 0.5W $0.40 pcX 55080
R 117 1k55 Holco 0.5W $0.40 pcX 55080
R 118 100R Dale 0.5W $0.20 Welborne V4-100
R 119 100R Dale 0.5W $0.20 Welborne V4-100
R 120 3k32 Dale 0.5W $0.20 Welborne V4-3.32k
R 121 3k32 Dale 0.5W $0.20 Welborne V4-3.32k
R 122 100R Dale 0.5W $0.20 Welborne V4-100
R 123 100R Dale 0.5W $0.20 Welborne V4-100
R 124 4k75 Holco 0.5W $0.40 pcX 50161
R 125 820R Holco 1W $0.50 pcX 62505
R 127 24R Kiwame 2W $1.10 pcX 66145
R 128 24R Kiwame 2W $1.10 pcX 66145
R 129 1k5 Riken 0.5W $2.40 pcX 62085
R 130 22k Riken 0.5W $2.40 pcX 62103
R 131 22k Riken 0.5W $2.40 pcX 62103
R 201 0R5 Mills 5W $1.85 pcX 62700
R 202 0R5 Mills 5W $1.85 pcX 62700
R 203 0R5 Mills 5W $1.85 pcX 62700
R 204 0R5 Mills 5W $1.85 pcX 62700
R 105 5k pot Bourns N/A RS 375-922
R 126 5k pot Bourns N/A RS 375-922
C101 560pF Polystyrene $0.75 pcX 65622
C102 1000uF BG NX 25V $12.95 pcX 60089
C103 1000uF BG NX 25V $12.95 pcX 60089
C104 100nF Polypropylene N/A RS 414-7614
C105 390pF Polystyrene $0.75 pcX 64140
C106 390pF Polystyrene $0.75 pcX 64140
C107 100pF Polypropylene $0.75 Welborne WM1
C108 100pF Polypropylene $0.75 Welborne WM1
C109 100nF Polypropylene N/A RS 414-7614
C110 10uF BG Std 16V $1.20 pcX 58643
C111 10uF BG Std 16V $1.20 pcX 58643
Hi PWatts-
Well with all those parts your gonna need a place to put them...
How's this for a place you can put those parts? 😀
Just in yesterday. Wife stuffing packages today.. Will ship them ALL out Monday.
And thanks for the list of parts and places to get them!!
Well with all those parts your gonna need a place to put them...
How's this for a place you can put those parts? 😀
Just in yesterday. Wife stuffing packages today.. Will ship them ALL out Monday.
And thanks for the list of parts and places to get them!!
Attachments
Boards look great!!! The component holes look a little small tho, but probably just the image size 🙂
Where can we buy halco/riken resistors online?
Aaron
Where can we buy halco/riken resistors online?
Aaron
I'm curious...
Hey, KSA 50 guys, can you explain what your interest is and fascination is with this amp that would lead you to put this sort of money and time into replicating it??
I think I read that this circuit is similar/identical to that used in early Brystons as well?
Being quite diplomatic about it, aren't there superior driver boards/circuits that can be used with an equivalent number of output devices yielding equal or better performance today??
And, to those using premium resistors and caps, do you expect that this will materially change the "sonic signature" of this amp compared to the stock Krell unit? And, do you want it to?
Signed,
...curious
🙂
_-_-bear
Hey, KSA 50 guys, can you explain what your interest is and fascination is with this amp that would lead you to put this sort of money and time into replicating it??
I think I read that this circuit is similar/identical to that used in early Brystons as well?
Being quite diplomatic about it, aren't there superior driver boards/circuits that can be used with an equivalent number of output devices yielding equal or better performance today??
And, to those using premium resistors and caps, do you expect that this will materially change the "sonic signature" of this amp compared to the stock Krell unit? And, do you want it to?
Signed,
...curious
🙂
_-_-bear
hmm...perhaps a couple of salient points,
Bear,
I can't speak for others, but my investment for the KSA50, nuts to soup, will end up being less than $100. I think it is a very small price to pay for having a neat new toy plus the experience of building and using it. Basically I buy nothing unless my cost is 1-10% of the new price, and have been very lucky in this regard. I have invested approx. $1000 total for all the major parts needed to make dozens of amps, since I have never heard the majority of the 'classics' I plan to make them all, and decide for myself if there is any substance to their reputation.
For me it's one of a connected set of hobbies, and as such not bound or confined by the realities of efficiency, logic or scientific analysis. Kind of like collecting stamps, restoring cars, watching any sort of sport, boating, even drinking fine wine...all complete wastes of time, effort and money, but enjoyed by millions.
My recently completed Aleph50 is but the first of many...the ksa50 is next,
Stuart
Bear,
I can't speak for others, but my investment for the KSA50, nuts to soup, will end up being less than $100. I think it is a very small price to pay for having a neat new toy plus the experience of building and using it. Basically I buy nothing unless my cost is 1-10% of the new price, and have been very lucky in this regard. I have invested approx. $1000 total for all the major parts needed to make dozens of amps, since I have never heard the majority of the 'classics' I plan to make them all, and decide for myself if there is any substance to their reputation.
For me it's one of a connected set of hobbies, and as such not bound or confined by the realities of efficiency, logic or scientific analysis. Kind of like collecting stamps, restoring cars, watching any sort of sport, boating, even drinking fine wine...all complete wastes of time, effort and money, but enjoyed by millions.
My recently completed Aleph50 is but the first of many...the ksa50 is next,
Stuart
Yup!
Helped my uncle restore and old Packard. No practical use or value in it at all. Sure was fun to drive though. Lots of good times with him do'in it.
Prosit
Helped my uncle restore and old Packard. No practical use or value in it at all. Sure was fun to drive though. Lots of good times with him do'in it.
Prosit
thanks for the site!! They have most of the resistors i need i think, but damn are they expensive!!!!
Oh well, price we pay hey 🙂
What resistors did the krell originally use? I want to use very good ones in the direct signal path, but half the others aren't that important (i.e. can be cheapo ones, so long as value is spot on).... Looking at the board there's not really any caps that are majorly important.... Is there any real "point" to using HIGH quality parts? Will "low" quality-mass produced parts suffice? I always hear people discussing this and it makes me wonder if it will be a worthwhile change?
Overall the amp for me will be "expensive" - mostly taking time and heatsink costs (about $45aus/channel), fans (which i can use for anything really, if it fails!) and toroids (most expensive) custom wound - work out about $150/us each.... that said i can make other projects with the toroids if it doens't work out i guess....
The point is to replicate or "better" the original krell design if possible, i'm making mine more powerful and also giving it a more stable power supply, similar cap value, but if i CAN improve it at all, i will try..... I might make my 3rd channel out of basic basic cheapo parts and see how it goes? Dunno yet!
Aaron
Oh well, price we pay hey 🙂
What resistors did the krell originally use? I want to use very good ones in the direct signal path, but half the others aren't that important (i.e. can be cheapo ones, so long as value is spot on).... Looking at the board there's not really any caps that are majorly important.... Is there any real "point" to using HIGH quality parts? Will "low" quality-mass produced parts suffice? I always hear people discussing this and it makes me wonder if it will be a worthwhile change?
Overall the amp for me will be "expensive" - mostly taking time and heatsink costs (about $45aus/channel), fans (which i can use for anything really, if it fails!) and toroids (most expensive) custom wound - work out about $150/us each.... that said i can make other projects with the toroids if it doens't work out i guess....
The point is to replicate or "better" the original krell design if possible, i'm making mine more powerful and also giving it a more stable power supply, similar cap value, but if i CAN improve it at all, i will try..... I might make my 3rd channel out of basic basic cheapo parts and see how it goes? Dunno yet!
Aaron
NUTTR, I've examined a KSA100, and it seems they've used Dale resistors, and Roedersteins for the 1000uF feedback caps. The film caps were of unknown pedigree. In my experience its really hard to discern quality above Dale in an amp with global feedback, so I guess generic metal film may sound the same 🙂 The 10uF electros can probably also be your local cheap variety. The only real important cap is the feedback ones, there I've heard a difference in sound when I changed a no-name bipolar to a BG NX (at more than 50 times the price). Especially as the board size doesn't allow for a nice 100nF bypass these feebback caps should prefereably be at least Elna Cerafine or Panasonic FC. As long as the pF caps aren't ceramic (although the newer COG types are pretty good), any dielectric should word; I merely took what fitted the board best. For applications where heat is involved (such as close to the drivers), polystyrene is a better choice, probably why the valve guys still swear to it. Silver mica is fine too, but generally too large physically. That leaves polypropylene, which I used for the remainder.
I'd appreciate some comments on AB comparisons between a channel buit with top end vs cheap components.
Pierre
I'd appreciate some comments on AB comparisons between a channel buit with top end vs cheap components.
Pierre
Re: I'm curious...
To me the Krell is very similar to the original GAS Son of Ampzilla.bear said:Hey, KSA 50 guys, can you explain what your interest is and fascination is with this amp that would lead you to put this sort of money and time into replicating it??
I think I read that this circuit is similar/identical to that used in early Brystons as well?
Being quite diplomatic about it, aren't there superior driver boards/circuits that can be used with an equivalent number of output devices yielding equal or better performance today??
And, to those using premium resistors and caps, do you expect that this will materially change the "sonic signature" of this amp compared to the stock Krell unit? And, do you want it to?
Signed,
...curious
🙂
_-_-bear
Well the most interesting part would be to hear if anyone has the chance to do a 1:1 side by side comparison with the original?
I am curious to know what if any differences are heard.
Fwiw, my impression of the sound of the original is that it had "funny" bass, and rather hard and harsh top end. I know people went ga-ga over it at the time, but neither I nor a whole bunch of other audio friends quite understood that.
And, since I live in "Krell country" here in the north east USA, I had many opportunities to audition the Krells in both showroom and private systems... my impression of the KSA series remained constant - and not due to some prejudice.
Oddly, the Reference 100 from the KSA era had far less of this "signature" than the KSA series - anyone know what the differences are/were??
At the time there were some cables that were fairly inductive that were popular with the KSA amps, I can't quite recall the name, but Krell adopted them and had their brand put on them. The reason that would have been "synergistic" is fairly obvious...
Oh, you guys who are building them really ought to confer and put up a single website showing the work in progress AND the results!! I hope you'll do that.
Get together with the KSA 100 guys too?
good building!
_-_-bear
I am curious to know what if any differences are heard.
Fwiw, my impression of the sound of the original is that it had "funny" bass, and rather hard and harsh top end. I know people went ga-ga over it at the time, but neither I nor a whole bunch of other audio friends quite understood that.
And, since I live in "Krell country" here in the north east USA, I had many opportunities to audition the Krells in both showroom and private systems... my impression of the KSA series remained constant - and not due to some prejudice.
Oddly, the Reference 100 from the KSA era had far less of this "signature" than the KSA series - anyone know what the differences are/were??
At the time there were some cables that were fairly inductive that were popular with the KSA amps, I can't quite recall the name, but Krell adopted them and had their brand put on them. The reason that would have been "synergistic" is fairly obvious...
Oh, you guys who are building them really ought to confer and put up a single website showing the work in progress AND the results!! I hope you'll do that.
Get together with the KSA 100 guys too?
good building!
_-_-bear
To Bear : What sound we may waiting from Krells ? Overkilled transformers and power supply, overkilled output stage, heavy loaded VAS ( = low closed loop gain ) give " heavy metal " sound ( similar to podium PA systems ). By my experience on Krells listen music mainly people, which like rock or heavy metal. These records are in mostly cases awfully distorted, so is free, if amp some distortion add 😎 .
