well..
Assuming you are using the same resistors(25r, 0r68):
4 pairs: r127,8: ~0w3 each. re1-8 ~7.3w each. ~480w/1r, ~31a peak
I should add the 80w power in the outputs is assuming 2 pairs, obviously with 3 and 4 pairs the power in the outputs is reduced proportionally.
Stuart
Assuming you are using the same resistors(25r, 0r68):
4 pairs: r127,8: ~0w3 each. re1-8 ~7.3w each. ~480w/1r, ~31a peak
I should add the 80w power in the outputs is assuming 2 pairs, obviously with 3 and 4 pairs the power in the outputs is reduced proportionally.
Stuart
I've stuffed the boards but I can't find the 27 volt, 3w Zeners. Can someone give me a part numper or source for those please?
Thanks, Terry
Thanks, Terry
don't need 3w
Terry,
You can use more normal 1/2 or 1/3w zeners they will work perfectly...there isn't much power dissipated. You can get them from digikey or mouser...the part numbers are a little confusing, the last 2 digits of the number are NOT the voltage, so you need to find a spec. table table of zeners and part numbers to find the correct ones...
If you search on the word zener in the digikey website, then choose 27v from the rightmost column I think you'll find what you need...mouser probably has much the same selection...
Stuart
Terry,
You can use more normal 1/2 or 1/3w zeners they will work perfectly...there isn't much power dissipated. You can get them from digikey or mouser...the part numbers are a little confusing, the last 2 digits of the number are NOT the voltage, so you need to find a spec. table table of zeners and part numbers to find the correct ones...
If you search on the word zener in the digikey website, then choose 27v from the rightmost column I think you'll find what you need...mouser probably has much the same selection...
Stuart
Regarding the zener diode: I used the BZX85 series. They are rated at 1,3W as you can see on the datasheet.
http://www.ortodoxism.ro/datasheets/good-ark/BZX85C6V8.pdf'
Regards
http://www.ortodoxism.ro/datasheets/good-ark/BZX85C6V8.pdf'
Regards
So do you guys want to make a concensus on what you want in regard to changes, and I'll do it. If it's just the hole changes and adding a couple of ccs boards, then thats minor. If it's anything else, then I think you're getting away from the original KrellClone concept. That's fine by me, as mine are up and running, and that's all I ever wanted, but it will involve more rework, and possibly another proto run, and more delay.
Your call...
Your call...
The boards like they are now are fine for me Al. I don't really get what all that CCS crap is so I don't think I will need it anyway. Was this in the original Krell?
Regards
Regards
I would want a CCS added Al. Those who don't want it can bypass it but I think it adds value, performance and most importantly flexibility.
K-
K-
The hole sizes have got to be changed. One can't use decent quality teflon wire they way they are now, look at the size wire Krell used in the orignals....obviously its was some kind of high end, very fine stranded Cardas or Kinber wire of that time period. As for the CSS its really for those that wanna make higher power amps out of this circuit. I don't intend to use it in mine but it may make building larger amps all the much easier for those that want to. It should be simple to add as an extension of the existing board and won't interfer with the way the present board is. I doubt that it will make any audible improvement either, the type of wire used in the amp is actually far more important. I also think we can skip another proto as long as everything else is left alone.
Mark
Mark
Monster cable was numero-1 in the 1980s.
Consider Mark.A.G. my spokesman, i'll just read the posts.
Consider Mark.A.G. my spokesman, i'll just read the posts.
Yea Jacco, I still have some of that monster stuff around here someplace in a box. I wired many a cinema with that stuff back then....
Mark
Mark
My 2 cents
Adjust the hole size
CCS is OK, but not needed and way down on my "to do" list
Let's have the boards.
Al , you have shown GREAT patience with this.
GeWa, The build Wiki is priceless. Thank You
Adjust the hole size
CCS is OK, but not needed and way down on my "to do" list
Let's have the boards.
Al , you have shown GREAT patience with this.
GeWa, The build Wiki is priceless. Thank You
Build wiki
bg40403
Can't take any credit for the wiki page, al I did was putting a link in my signature for easier access. The true kloners who contributed to the building page are, Pinkmouse, Mark A. Gulbrandsen, K-amps, lgreen, jacco vermeulen, Stuart Easson, rabstg. Did I forgot somebody?
P.S. I also noticed that a word was edited out in one of my previous posts. Sorry for the bad choise of phrasing, won't happen again.
Regards
bg40403
Can't take any credit for the wiki page, al I did was putting a link in my signature for easier access. The true kloners who contributed to the building page are, Pinkmouse, Mark A. Gulbrandsen, K-amps, lgreen, jacco vermeulen, Stuart Easson, rabstg. Did I forgot somebody?
P.S. I also noticed that a word was edited out in one of my previous posts. Sorry for the bad choise of phrasing, won't happen again.
Regards
the CCS...
...really isn't necessary, I don't think it adds value in the normal design, though I don't have any listening tests to justify it's inclusion or exclusion...
It didn't show up in Krell designs until a later version, where it appeared in the front end, then later went away to reappear in the Vas...which also became mosfet based...
I will make PCBs for anyone that wants them, so unless there is really no overhead finanically and very little timewise, I vote to leave it off GB board.
There are other things I want to investigate (better CCS, current mirrors, front end regulation?, dual slope VI limiter) etc. I will update everyone as these things evolve and if they are useful, make a bigger small board...
Stuart
...really isn't necessary, I don't think it adds value in the normal design, though I don't have any listening tests to justify it's inclusion or exclusion...
It didn't show up in Krell designs until a later version, where it appeared in the front end, then later went away to reappear in the Vas...which also became mosfet based...
I will make PCBs for anyone that wants them, so unless there is really no overhead finanically and very little timewise, I vote to leave it off GB board.
There are other things I want to investigate (better CCS, current mirrors, front end regulation?, dual slope VI limiter) etc. I will update everyone as these things evolve and if they are useful, make a bigger small board...
Stuart
I've got a question about the heatsink and Q111. I am planning to use a Hafler P500 heatsink tunnel. It is designed to hold 12, TO3 cases. I plan to use 3 pairs of MJ15003/4 per channel. I also plan on mounting Q111 on the heatsink somewhere to track the output temps. Do I need to isolate the plate of Q111 or can it be mounted to the heatsink with just grease? I have Kapton tape but was concerned about the bolt. The heatsink will be grounded to the case.
Thanks, Terry
Thanks, Terry
Yes, you will need to insulate the device. You need a plastic bushing that fits over the bolt.
Terry,
Just buy yourself some TO-220 mounting kits ala NTE or that sort of thing. That way you get ALL the needed hardware to properly mount the tab transistors. Any shorts between the metal tab and chassis ground and the amp will more than likely permanently head south pretty dang fast.
Mark
Just buy yourself some TO-220 mounting kits ala NTE or that sort of thing. That way you get ALL the needed hardware to properly mount the tab transistors. Any shorts between the metal tab and chassis ground and the amp will more than likely permanently head south pretty dang fast.
Mark
q111
Terry,
If the transistor you are using is the 2sc3955, you don't have to worry baout insulating it, the package is completely isolated. If it is not the 2sc3955 type and has exposed metal (mje1503x) you must insulate it. When I don't have any to220 insulators kicking around I use a pair of good kitchen scissors to cut up a to3 one...
Stuart
Terry,
If the transistor you are using is the 2sc3955, you don't have to worry baout insulating it, the package is completely isolated. If it is not the 2sc3955 type and has exposed metal (mje1503x) you must insulate it. When I don't have any to220 insulators kicking around I use a pair of good kitchen scissors to cut up a to3 one...
Stuart
Q111
Terry, just to echo what stuart says, I've if Q111 is a 2sc3955 (the part specified on the schematic and parts list) you don't have to isolate it because the package is not live.
I think the other posters who recommended ways to insulate must have momentarily forgot that this is the specified part and that it is encapsulated and needs no special mounting insulation. At least the ones I have don't.
Terry, just to echo what stuart says, I've if Q111 is a 2sc3955 (the part specified on the schematic and parts list) you don't have to isolate it because the package is not live.
I think the other posters who recommended ways to insulate must have momentarily forgot that this is the specified part and that it is encapsulated and needs no special mounting insulation. At least the ones I have don't.