Krell KSA-250

WOPL Sniffer

WOPL Sniffer

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#41
I think the owners need to think about using the fans I use except get the 17" ones. They sit on the floor (Usually carpet or rug), and it causes issues with the air flow.

These amps put out some serious heat being Class A and I think other amp owners report like 8 amps even at idle..... FUCK THAT. This will be my one and only Krell-Job.... Even with 60Lbs worth of heat sinks it's not enough. The SilPads were stiff as cardboard when I pulled them. I think it would be mandatory to service these things about every 5 years.
 
WOPL Sniffer

WOPL Sniffer

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Gepetto said:
Perry, you will have to ask the COO to see what he thinks... HUH??

Dayam, you pay that much for an amp and you get a toasted board? I guess I could somewhat understand that with Phase Linear S2 amps but with a Krell!!

There I combined Perryisms and Leeisms in the same reply :cool:
Click to expand...

Joe, That's why the COO didn't like me........ I told him about the cooked Slow Start Board and the layout/engineering. Others must have taken pity on me and hooked me up.
 
WOPL Sniffer

WOPL Sniffer

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WOPL Sniffer said:
I think the owners need to think about using the fans I use except get the 17" ones. They sit on the floor (Usually carpet or rug), and it causes issues with the air flow.

These amps put out some serious heat being Class A and I think other amp owners report like 8 amps even at idle..... FUCK THAT. This will be my one and only Krell-Job.... Even with 60Lbs worth of heat sinks it's not enough. The SilPads were stiff as cardboard when I pulled them. I think it would be mandatory to service these things about every 5 years.
Click to expand...

OH, and a service at 5 years would end up costing about a grand, maybe more with new bulk caps and new outputs.
 
WOPL Sniffer

WOPL Sniffer

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Now trying to figure out why they used MJF15030/31 instead of MJE15030/31. Joe??? I think they had OnSemi come up with the MJF but not sure. It looks like the same transistor though.
 
Gepetto

Gepetto

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#47
WOPL Sniffer said:
I think all I see different is the plastic case of the MJF's and the MJE's have the metal tab which would require the use of an insulator except for the free standing units.
Click to expand...
Surprised to see those in a Krell, usually in low cost applications
 
WOPL Sniffer

WOPL Sniffer

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I think it may have been a "Bean Counter" choice since it doesn't require an insulator???? But, there is only a couple which lay down. Only one on the Slow Start board.
 
krellmk

krellmk

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#49
Perry dem 700 Ohm resistors on the soft start board get hot very hot ... with the kinna current this thing put out it can double as a welding machine.
 
WOPL Sniffer

WOPL Sniffer

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#51
WOPL Sniffer said:
I think it may have been a "Bean Counter" choice since it doesn't require an insulator???? But, there is only a couple which lay down. Only one on the Slow Start board.
Click to expand...

The plastic case of these (4 pre drivers, 2 NPN. 2 PNP), are screwed down to the heat sink on each channel, and make shitty contact at that. There is no pads or thermal grease to even help with the transfer of heat. I will address that asap. I did find some of these plastic case (MJF15030/31) transistors and just so I didn't have to worry about insulating the ones that lay down, I bought some and I will work on that problem. All the ones that stand up, will get MJE15030/31 and if they put out X amount of heat, they will get heat sinks. Screw the Old School Krell guys.... If their system don't work, it will get the "Perry" System which better work or it gets the rifle treatment.......
 
WOPL Sniffer

WOPL Sniffer

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After $1000 worth of parts on the Credit Card, I hope the finish date aint too far off. I was going to milk this for the next 10 months but I can't handle unfinished stuff in my shop, sitting around gathering dust... Bugs me.
 
laatsch55

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#56
WOPL Sniffer said:
The plastic case of these (4 pre drivers, 2 NPN. 2 PNP), are screwed down to the heat sink on each channel, and make shitty contact at that. There is no pads or thermal grease to even help with the transfer of heat. I will address that asap. I did find some of these plastic case (MJF15030/31) transistors and just so I didn't have to worry about insulating the ones that lay down, I bought some and I will work on that problem. All the ones that stand up, will get MJE15030/31 and if they put out X amount of heat, they will get heat sinks. Screw the Old School Krell guys.... If their system don't work, it will get the "Perry" System which better work or it gets the rifle treatment.......
Click to expand...
Is the rifle treatment what it sounds like ??
 
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