to3 construction
Terry,
Hardwiring is relatively easy with TO3 packages. I have started to use sockets as well, but it's a slight additional hassle in assembly. The fact that there are only 4 devices per channel helps too.
Pardon me if the question was already answered...The original, second and possibly all versions of the KSA50 had 2 pairs of outputs per channel, these were krell branded mj15003/4 pairs. The move to the TO247 package is what prompted our use of 3 devices, increased safety margin for a lower rated device. Rb does not exist in any Krell schematic I've seen, and when driving low impedances could cost you output power or worse simply fail, costing you output devices...I'm using a wire link, the emitter resistors are a better way of ensuring sharing.
If you want to use, 4 pairs of mj15003/4 or mj21193/4 outputs per channel you can easily create an amp that will be 'similar' to a KSA100. A 'real' KSA100 has a number of 'detail' changes, ie slightly higher, front end voltages, a little more gain, and in later versions an additional set of drivers.
To make a KSA100 type amp you would need voltage rails that at full load were still in the 45+ volt range (IIRC Krell had 55v at idle), a minimum of 2.5A of idle current, and heatsinks in the 0.1c/W range. If you plan on using the 'full' class B capability you'd want more heatsinking.
email me if you need more info...
Stuart
Terry,
Hardwiring is relatively easy with TO3 packages. I have started to use sockets as well, but it's a slight additional hassle in assembly. The fact that there are only 4 devices per channel helps too.
Pardon me if the question was already answered...The original, second and possibly all versions of the KSA50 had 2 pairs of outputs per channel, these were krell branded mj15003/4 pairs. The move to the TO247 package is what prompted our use of 3 devices, increased safety margin for a lower rated device. Rb does not exist in any Krell schematic I've seen, and when driving low impedances could cost you output power or worse simply fail, costing you output devices...I'm using a wire link, the emitter resistors are a better way of ensuring sharing.
If you want to use, 4 pairs of mj15003/4 or mj21193/4 outputs per channel you can easily create an amp that will be 'similar' to a KSA100. A 'real' KSA100 has a number of 'detail' changes, ie slightly higher, front end voltages, a little more gain, and in later versions an additional set of drivers.
To make a KSA100 type amp you would need voltage rails that at full load were still in the 45+ volt range (IIRC Krell had 55v at idle), a minimum of 2.5A of idle current, and heatsinks in the 0.1c/W range. If you plan on using the 'full' class B capability you'd want more heatsinking.
email me if you need more info...
Stuart
Al, do you have the PCB dimensions for the individual boards? ie. main & driver/outputs
Trying to work out if I can squeeze these into the back of the speakers, I guess the heatsink will be the real problem.
What sort of trafo would I be looking at the power a 3 amps from a single unit? 2000VA?
OR
If I went with a mono setup what rating trafo for each channel?
Also what voltages on the trafo for the 6 output version? Would 40v 1000VA be OK as I have a couple of them here or is that pushing the 6 outputs a little too far?
Cheers,
Ant
BTW: hows the BOM comming along? You don't have something preliminary you could email me so I can start gathering parts would you? Please
Zeroex_15@hotmail.com
Trying to work out if I can squeeze these into the back of the speakers, I guess the heatsink will be the real problem.
What sort of trafo would I be looking at the power a 3 amps from a single unit? 2000VA?
OR
If I went with a mono setup what rating trafo for each channel?
Also what voltages on the trafo for the 6 output version? Would 40v 1000VA be OK as I have a couple of them here or is that pushing the 6 outputs a little too far?
Cheers,
Ant
BTW: hows the BOM comming along? You don't have something preliminary you could email me so I can start gathering parts would you? Please
Zeroex_15@hotmail.com
So I'm looking at the wiki and it seems to me that since each board from the factory has 1 main, 1 driver, and 2 output boards, do we still need to put an individual amount for Main, Output, and such in the table?
Can I just put 2 for main, and thus be getting 2 Main, 2 Driver, and 4 Output? I know the wiki has changed I'm just trying to get this right.
- Brian
Can I just put 2 for main, and thus be getting 2 Main, 2 Driver, and 4 Output? I know the wiki has changed I'm just trying to get this right.
- Brian
shinobiwan
are the voltages you are quoting for your transformers before or after rectification?
40v DC rails unloaded will probably be fine, because the voltage will drop a little as you bias up each channel, 6 channels are going to pull ~11 amps constantly, so likely no problem. OTOH if that is the AC voltage, you are going to have too many DC volts (~57v) after rectification for 3 output pairs, you would need 5 or 6 pairs, and would end up with something more like KSA100 channels, and a huge amount of heat...~1600watts for 6 channels...
If you want any decent margin for low impedance operation etc you would need to buy a huge transformer, 2kw would be a good start...
HTH
Stuart
are the voltages you are quoting for your transformers before or after rectification?
40v DC rails unloaded will probably be fine, because the voltage will drop a little as you bias up each channel, 6 channels are going to pull ~11 amps constantly, so likely no problem. OTOH if that is the AC voltage, you are going to have too many DC volts (~57v) after rectification for 3 output pairs, you would need 5 or 6 pairs, and would end up with something more like KSA100 channels, and a huge amount of heat...~1600watts for 6 channels...
If you want any decent margin for low impedance operation etc you would need to buy a huge transformer, 2kw would be a good start...
HTH
Stuart
Thanks for the BOM Al.
Just a quick question...
The caps that don't have ratings, what sort of standard value is fine? What type too and the lead pitch for the PCB.
Same goes for the resistors too.
Actually maybe I should just wait for you final version of the BOM. Don't sweat it, afterall we've got around another month or so until the boards will be with us
Just a quick question...
The caps that don't have ratings, what sort of standard value is fine? What type too and the lead pitch for the PCB.
Same goes for the resistors too.
Actually maybe I should just wait for you final version of the BOM. Don't sweat it, afterall we've got around another month or so until the boards will be with us