Capacitor Krell KSA 100

[Elso Kwak]

2sc3281

2SC3281 and sister/brother are not available anymore ( the original Toshiba's that is ).

Hi Jean-Paul,
Actually I meant MJ3281A and MJ1302A. These are now used by Madrigal in Mark Levinson gear and by Krell. Krell simply placed 86 or 83 before the typonumber to make there own type#. Not too difficult to figure out. These types were a short time on the Onsemi website but seem now to be discontinued. These are 30MHz (typ.) Ft devices. Not recommended for this old Krell KSA-100!
😎
Your "commercial" for the Blackgates is well taken and if they fit in I will give them a try in my Ampzilla II!.
Thanks.🙂

 

[RobPhill33]

If the differential transisitors were replaced with the common 2N5401/2N5551 would that hinder its performance?

 

[Audiofanatic]

Hi Elso and others,

That explain the failing of the KSA100 Clone!
I'v used 30 MHz output devices!

What about the 2N5551 and his brother/sister in the dif. stage?

Thanks.

Audiofanatic😉

 

[Elso Kwak]

Inputtransistors

Hi All,
I can't read the typenumbers of the inputtransistors. Too old eyes???😕 2N6421 and 2N6433???
I am confused as the 2N6421 is a TO-66 case. (small TO-3)
The Son of Ampzilla and Ampzilla are very similar to the Krell. With the supply voltages of the Krell the 2N551 and 2N5401 might work. The Ampzilla uses the 2N5551 and 2N5401. I don't dare to put my hand into the fire though
Ampzilla schematics:
http://home.kimo.com.tw/skychutw/ampzilla/

Audiofanatic,
I was under the impression you got the Krell clone working. Glad to be of help.😉

 

[RobPhill33]

Those are the values I see. When looking at a picture of the driver board I see 13 transistors, but only see 9 on the schematic. I must be missing something.

 

[Tube_Dude]

TUbe_Dude news glass lenses...

When looking at a picture of the driver board I see 13 transistors, but only see 9 on the schematic. I must be missing something

I see 11 transistores in the schematic...

Jorge

 

[jean-paul]

Mmm, I see clearly that there are total 17 transistors ! Take a closer look at the power transistors. It says 4 x at each power transistor. So 8 x power transistors + 9 drivers/bias etc. = 17.

 

[Tube_Dude]

Mathematcly correct...

11+ 6= 17

this last 6 are not in the picture...but in the legend!...

so that´s right!

Jorge

 

[RobPhill33]

i meant 9 before the OPS on the schematic

 

[jean-paul]

Sorry RobPhill, I was only joking. Can't explain the picture compared to the schematic. There are 13 transistors on the driverPCB as you said. Maybe the schematic is wrong.

Alex Helge has one. When he has finished soldering the new caps he maybe can check his KSA100 !?!?

 

[RobPhill33]

Good idea Jean-Paul

 

[Alex helge]

Hi
The schematic is of KSA 100 MK 1 driver board.
I have the driver board of the Mk 2.

I think can the KSA 100 to improve,but the rhythm won´t better.

best regards and thank
Alex

 

[Alex helge]

KRELL KSA 100

A picture Krell KSA 100

 

[Tube_Dude]

So the KSA 100 could be improved!

My guess and returning to the foto of post #20 is that Krell have evoluated from a double follower for a much more perfomante
triple follower...

Then back to the foto:
- the 4 transistors in the individuals eatsinks...are the pre drivers...two in paralel
-The 5 transistors in the same eatsink are the drivers...two in paralel more the VBE multiplier...

Total 9

Jorge

PS: is just a guess without seeing the boards...

 

[rickpt]

Here we look at the internal pic’s of an amp we all know that sounds very good, even by today standards

As I am looking through the power supply. I can’t see any polyester or polypropylene bypass cap or neither can I see a snubber cap on the bridge rectifier .am I going blind or the golden rule of always applying bypass caps and snubbers doesn’t apply here…
😉

not even spikes/cones...

 

[Alex helge]

KRELL KSA 100

driver board KSA 100

 

[Alex helge]

KSA 100 Board

driver board

 

[umut1001]

best way

it had been long time..but i want to get the right answer..what is the best replacement capacitor in feedback path for krell amp ? there are many choices. nonpolar, mkp ,nonpolar paralleled mkp, nichicon gold tune , or cascode +--+ cap ?what is the most important subject?esr or esl or other things ? which is the best way ? thank you

 

[AndrewT]

nonpolar, mkp ,nonpolar paralleled mkp, nichicon gold tune , or cascode +--+ cap ?

is this the pair of back to back 1mF electrolytics?

I see only one choice! not many.

 

[umut1001]

Hi Andrew..using mkp will be an extreme application for example mundorf 560uf x 2. I used mkp in the feedback of gainclone in the past..it was paralell of 5pieces of 10uf.totally 50uf..because of mkp's sonic specifications it sounded very well..I dont know that i can explain my problem.sorry for bad English.which cap can give the best sound? some people parallels 1uf with 1000uf in the feedback.some uses nonpolar caps..what do you think about this subject ?