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Old 17th April 2006, 01:13 PM   #11
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Actually the KSAS-100 Mk-2 is very different than the KSA-50 Mk-2. The addition of cascoded pre-driver stages and multiple drivers for the output stage. Also MOSFETS thrown in as CSS .... its not at all like the KSA-50 except for the input stage. Krell sold many more KSA-100's than KSA-50's so It couldn't have been a bad amp. The KSA-80B that I owned was far more complicated than KSA-100 MK-2 and sounded excellent!


KSA-100 MK-2

Pre 1983 KSA-100


Mark
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Old 17th April 2006, 01:14 PM   #12
konst is offline konst  United Kingdom
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If we start now, we will probably get them up and running reliably just in time for autumn - you wont have to stock up on wood for the fireplace
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Old 17th April 2006, 01:31 PM   #13
kvholio is offline kvholio  Netherlands
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If my memory is correct ksa-100 was first Krell that was adequate for driving Apogees at full swing.Years ago i listened to ksa-100/caliper combo (PAM preamp, sony esd557 as transport with Meridian DA-converter i think) many times and was VERY impressed with the sound this setup produced. just dont have the $$$$
I wont be building ksa-100 in near future. Too busy building ksa-50 and chasing monster

With kind regards,

Klaas
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Old 17th April 2006, 01:37 PM   #14
konst is offline konst  United Kingdom
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i think there is some confusion here about versions of the MKII, there were two MK1 versions, prior to 83 and post to 83, I am not sure but i think the MKII arrived around 88 or 89, i was selling those in Germany at time, but can't remember exact dates, sorry.

Both the MKI version were bipolar only.
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Old 17th April 2006, 01:43 PM   #15
awpagan is offline awpagan  Australia
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Quote:
Originally posted by kvholio
If my memory is correct ksa-100 was first Krell that was adequate for driving Apogees at full swing.Years ago i listened to ksa-100/caliper combo (PAM preamp, sony esd557 as transport with Meridian DA-converter i think) many times and was VERY impressed with the sound this setup produced. just dont have the $$$$
I wont be building ksa-100 in near future. Too busy building ksa-50 and chasing monster

With kind regards,

Klaas
just put some flashing lights on the krell, and the monster will come to you
allan

ps thought
after the krell has cooled down.
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Old 20th April 2006, 02:13 PM   #16
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Remember Mark, that the best boards makes BB.....
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Old 20th April 2006, 02:55 PM   #17
googler is offline googler  United States
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Quote:
Originally posted by Mark A. Gulbrandsen
I am also able to supply you with the Pinkmouse boards minus the OP sections @ 12.00 each if you like. I have 6 that way in stock....

Mark
Hi Mark,
Does that mean that you have a few OP sections laying around as well? I'm still looking for 2 sets (4 boards) of Pinkmouse OP boards.

~Brad
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Old 20th April 2006, 06:38 PM   #18
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Default KSA 100 etc..

Hi
My intention is to build four KSA 100 based on the KSA 50 (Als board).

But for the output devices (MJ15003/4) and for the driver devices I plan to make my own boards.

I plan to use one driver pair to each two pair output devices and it will be at least 8 pair of output devices per amp (only mono blocks) It will then be four pair of driver devices on my new driver board.
Any tip or comments how to design those board is welcomed ?

BTW, anyone bought cheap transistors from the Chine/Hong Kong ?
May be a tip though I have: MJ15003/4 priced at $0.55 each (original Motorola/ON.Semi) as an example.

Regards
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Old 21st April 2006, 12:28 AM   #19
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Quote:
Does that mean that you have a few OP sections laying around as well? I'm still looking for 2 sets (4 boards) of Pinkmouse OP boards.
K-Amps got them all!

Flodstroem,

Since you are almost doing the entire KSA-100 MK-2 with the exception of some of the preceeding stages might I suggest that we just do an actual board for the KSA-100 MK-2 including both TO-3 and TO-247 OP boards instead. I'm not sure that the preceeding stages of the KSA-50 can supply enough drive current for 2 pairs of drivers when operating at low impedances. Take a look at the actual schematic of the 100 MK-2 and I think you will agree that Dan went to great lengths to be sure that each preceeding stage was able to make its mark. Also those obsolete VN0210N5 and VPO210N5 devices only operate at about 3 mils so good subs are Zetex ZVP3310 and ZVN3310 and they are readily available and dirt cheap. The 1N5309 current limiter diodes are still made by MicroSemi Corp and in stock at Mouser.

One can also take this amp one step further and add the regulated supplies for the front end and driver stages that were in the KMA-100.

If Al is tied up with other stuff up a friend of mine that does board design at GE Medical may be able design the boards.

Of I can get at least a few others interested in this I will start a new thread for Kloning the Krell KSA-100 MK-2 and then we can proceed. Let me know if you're interested.....

Mark
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Old 21st April 2006, 12:42 AM   #20
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Default current...

...is a strange thing in an output stage...

Don't take this as meaning we shouldn't make a ksa100mk2 pcb set but...

According to most everything I've read, and so far tried, the more transistors there are in the output stage, the less current is needed from the drivers, all else being equal...ie using 3 pairs of the plastic power transistors will stress the drivers less than using 2 pairs of the to3s...

Using 5 or 6 pairs of the plastic transistors would use less current still...and since the ksa50 can drive 1 and 2 ohm loads without failing, I have to assume the ksa100 can do the same, heatsinks and power supply being the limiting factor...AndrewT has a spreadsheet that can tell you how many transistors you need for any given level of output into any particular load. Ideally the drivers need their own SOAR calculations, or you can just do as I did and go big...

I used the original board with 100v rails, mpsaX2 transistors and the CCS on the front end to keep everything alive to drive over 900w peak into 8ohms, at which point the rails had dropped to 85v or so...oh and I had 20 pairs of the to3 output transistors, ther drivers being a pair of the plastic outputs...no muss, no fuss. I don't have the means to measure distortion etc at this juncture, but assuming the PC based rightmark system can do a decent job it should be ready to go in the next couple of weekends at which point I may be able to tell whether there are other issues...

I am finally back to the point where I can work on this stuff, so I hope to be able to report something to all those that have been so patient...

Stuart
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