Hi Itsmee
You can find similar binding posts on Partsconexion (connectors_bind_vampire) made by Vampire.
You can find similar binding posts on Partsconexion (connectors_bind_vampire) made by Vampire.
I liked the Propeller binding post best - made from copper not brass, but they are not fully insulated, some heatshrink would sort that out.
https://www.madisound.com/store/product_info.php?products_id=9043
But I will probably buy these ones, fully insulated and no import duty
Lautsprecher Shop Intertechnik - K220RT | Accessories and Miscellaneous > Terminals and connectors > binding posts
https://www.madisound.com/store/product_info.php?products_id=9043
But I will probably buy these ones, fully insulated and no import duty
Lautsprecher Shop Intertechnik - K220RT | Accessories and Miscellaneous > Terminals and connectors > binding posts
Hi All,first post back on this thread for about two years. Due to unexpected events I had to take a break from the Krell clone I was building but now I am in a position to continue with it. I need some help as I have forgotten quite a few things.
I am building a lower powered version of the KSA50 with 24 volt rails. Andrew T kindly assisted with component value changes that were necessary to allow the amplifier to run correctly with the lower voltage rails. I am using the Delta Audio PCB's.
I need advice on the following:
1) Can the driver transistors MJE15032 and 15033 be mounted on the main heatsink or should they be mounted on a seperate one?
2) The thermal tracking transistor 2SC3955 should be mounted on the main heatsink ?
3) I have enough MJL21193 flatpack output transistors but no MJL21194 and from my suppliers they recomend 2SC5200 as a replacement. Is this correct? I was going to use two in parrallel for each channel.
Thanks,
Alan
I am building a lower powered version of the KSA50 with 24 volt rails. Andrew T kindly assisted with component value changes that were necessary to allow the amplifier to run correctly with the lower voltage rails. I am using the Delta Audio PCB's.
I need advice on the following:
1) Can the driver transistors MJE15032 and 15033 be mounted on the main heatsink or should they be mounted on a seperate one?
2) The thermal tracking transistor 2SC3955 should be mounted on the main heatsink ?
3) I have enough MJL21193 flatpack output transistors but no MJL21194 and from my suppliers they recomend 2SC5200 as a replacement. Is this correct? I was going to use two in parrallel for each channel.
Thanks,
Alan
My first post here. Alibear i'm curious about your down scaled KSA50 as the HIFIDIY A-20 caught my eye. Mostly I just loved what I heard when I was able to audition a real Krell KSA and it seems that these amps have either become treasured rarities or have gone the way of the dodo. Seems the best way to obtain this sound is to build it yourself.
I have seen some awesome products from some of the posters and I have to say I am a little jealous of what I have seen.
I have seen some awesome products from some of the posters and I have to say I am a little jealous of what I have seen.
Hi all, ED062178, have just read your post. I am away from home for a couple of days but when I return I can post some details if you are still interested.
I had a lot of help from some very able people on this thread.
If any of the information I have is useful to you you are more than welcome.
Alan
I had a lot of help from some very able people on this thread.
If any of the information I have is useful to you you are more than welcome.
Alan
Hello Alibear,
I have the pinkmouse boards, so my arrangement may be a little different...
1) Can the driver transistors MJE15032 and 15033 be mounted on the main heatsink or should they be mounted on a seperate one?
I have mine bolted to a aluminum angle iron that is bolted to the main heatsink. They should be thermally be coupled to the main sink. Remember that the metal tabs on those transistors carry - and + rail voltage, so you need to electrically isolate them from the sink, as the heatsink should be grounded through the chassis. I kept blowing my negative rail fuses to the main board before I realized one of the three transistors was not properly electrically isolated from the sink.
2) The thermal tracking transistor 2SC3955 should be mounted on the main heatsink ?
I do not have any other transistors beside the output transistors and the three MJE15033 / MJE15032 mounted on the main sink.
3) I have enough MJL21193 flatpack output transistors but no MJL21194 and from my suppliers they recomend 2SC5200 as a replacement. Is this correct? I was going to use two in parrallel for each channel.
I would not mix the manufacturers of the output PNP / NPN transistors. I do not believe the MJ21194 and 2SC5200 are very close matches. Look at the spec sheets. If you go with the 2SC5200, go with its compliment - the 2SA1943 (this is the pairing I have). Or stick with the MJ21194 / MJ21193 - just put up a wanted in the Swap meet for them if you don't have them - you will find someone to sell or give them to you...
I have the pinkmouse boards, so my arrangement may be a little different...
1) Can the driver transistors MJE15032 and 15033 be mounted on the main heatsink or should they be mounted on a seperate one?
I have mine bolted to a aluminum angle iron that is bolted to the main heatsink. They should be thermally be coupled to the main sink. Remember that the metal tabs on those transistors carry - and + rail voltage, so you need to electrically isolate them from the sink, as the heatsink should be grounded through the chassis. I kept blowing my negative rail fuses to the main board before I realized one of the three transistors was not properly electrically isolated from the sink.
2) The thermal tracking transistor 2SC3955 should be mounted on the main heatsink ?
I do not have any other transistors beside the output transistors and the three MJE15033 / MJE15032 mounted on the main sink.
3) I have enough MJL21193 flatpack output transistors but no MJL21194 and from my suppliers they recomend 2SC5200 as a replacement. Is this correct? I was going to use two in parrallel for each channel.
I would not mix the manufacturers of the output PNP / NPN transistors. I do not believe the MJ21194 and 2SC5200 are very close matches. Look at the spec sheets. If you go with the 2SC5200, go with its compliment - the 2SA1943 (this is the pairing I have). Or stick with the MJ21194 / MJ21193 - just put up a wanted in the Swap meet for them if you don't have them - you will find someone to sell or give them to you...
Last edited:
Hi all, ED062178 I used + and - 24 volt rails, each channel had it's own 18-0-18 300Va transformer, 2 bridge rectifiers and 4 47,000micro farad capacitors in a C-R-C configuration.
The only modifacation that I carried out was to the zener diodes and their associated resitors around the LTP.
I used the the Jan Dupont PCB and here is a list of the components I changed:
R108 to 1.3K ohm
R109 to 1.3K ohm
R110 to 4.7K ohm
R111 to 4.7K ohm
ZD101 to 13 Volt
ZD102 to 13 Volt
These changes allowed the LTP to be biased correctly ( many thanks to Stuart Eason )
I have set the output bias at 1.4A which gives approx 29 watts into 8 ohms.
I have used passive cooling with 400mm x 130mm x 40mm heatsinks for each channel. these run 25C above ambient. Heat is a big problem.
Sounds nice but I don't know if I can convince the wife to let me leave it in the lounge ( too big, too hot, too ugly ) and the amplifier is.
Also check out JLH.
John 65B and Andrew T I have used 21193 and 21194 TO3 packages
Thanks for all your help, much appreciated.
Alan
The only modifacation that I carried out was to the zener diodes and their associated resitors around the LTP.
I used the the Jan Dupont PCB and here is a list of the components I changed:
R108 to 1.3K ohm
R109 to 1.3K ohm
R110 to 4.7K ohm
R111 to 4.7K ohm
ZD101 to 13 Volt
ZD102 to 13 Volt
These changes allowed the LTP to be biased correctly ( many thanks to Stuart Eason )
I have set the output bias at 1.4A which gives approx 29 watts into 8 ohms.
I have used passive cooling with 400mm x 130mm x 40mm heatsinks for each channel. these run 25C above ambient. Heat is a big problem.
Sounds nice but I don't know if I can convince the wife to let me leave it in the lounge ( too big, too hot, too ugly ) and the amplifier is.
Also check out JLH.
John 65B and Andrew T I have used 21193 and 21194 TO3 packages
Thanks for all your help, much appreciated.
Alan
Awesome, thank you again Alan. I really like over building things and tuning down an amp like the ksa50 sounds awesome. I have also been looking at the JLH amps though there is some heavy debate on the 1969 version and the 1996 version. I heard the Krell as a youngster and was more than impressed by what I can only describe as concert like performance. I do like hearing the details in music but I am not the usual audiophile in that I listen to rock and techno music as much as classical and jazz. I loved the aggressive tight low end of the Krell. I doubt this will be my only venture into diy hifi but its always nice to get the bench mark down before spiraling out. I have been unable to locate the dupont boards, his website seems to be down unless the same boards are of the many available on ebay. So many questions, fortunately time is on my side. Thank you again cant wait to get a board and dig in
Wish I could help you but I only have two extras that I am holding on to in case my KSA-50 MK2 flames out some day. In fact my amp now has thousands of operating hours and has taken lots of abuse without so much as even a blip. Dan the man certainly came up with a super stable design in the KSA-50. Have you checked Ebay? They used to sell the boards from China on there...
Mark
Mark
PCB KSA50
I bought the PCB Jims Audio
I'm waiting .. rsrsrs
Best regards
Hello Mark
I bought the PCB Jims Audio
I'm waiting .. rsrsrs
Best regards
Looks pretty good... I don't like the red color though. It IS very definately the MK-2 version which is considerably better amplifier then the original version. You will need a very large heat sink for those drivers and to be honest this driver board looks like it could also be a KSA-100 mk-2 if you added more OP transistors and probably change some other parts on the board. For KSA-50 you really only need one plus and minus driver transistor... not two on each side. The one in the middle is the bias tracking transistor, you will definately need that!
So when you assemble it you might compare it to the pictures on this site of the second version of KSA-50 board and see exactly what parts you need to stuff in there before you order all the parts...
Mark
Update: It is actually the KSA-100 board. I looked through his store and he sells the same thing with two additional OP boards...
So when you assemble it you might compare it to the pictures on this site of the second version of KSA-50 board and see exactly what parts you need to stuff in there before you order all the parts...
Mark
Update: It is actually the KSA-100 board. I looked through his store and he sells the same thing with two additional OP boards...