True but if you check DigiKey and Mouser's ridiculous overseas shipping charges you'll understand non-US builders' chagrin 
But yeah Mark's right, everything else is pretty easy to source from most vendors. The original used Dale 0.5W resistors which can be bought from Welborne labs. No real point in going more expensive, and since they're not so expensive worth it over generic metal films.
The 100nF's were Roederstein axial films, and the pF values (680, 62, 20) were all silvered mica, all stocked by Parts Connexion at $0.75 each but polystyrene will do nicely too, just check if it'll fit on the board. For the 1000uF feedback cap use something nice, but check for low ESL - no point in low ESR since the cap is in series with 825ohms anyway
But yeah Mark's right, everything else is pretty easy to source from most vendors. The original used Dale 0.5W resistors which can be bought from Welborne labs. No real point in going more expensive, and since they're not so expensive worth it over generic metal films.
The 100nF's were Roederstein axial films, and the pF values (680, 62, 20) were all silvered mica, all stocked by Parts Connexion at $0.75 each but polystyrene will do nicely too, just check if it'll fit on the board. For the 1000uF feedback cap use something nice, but check for low ESL - no point in low ESR since the cap is in series with 825ohms anyway
DigiKey and Mouser's ridiculous overseas shipping charges
Indeed, and regular suppliers don't sell the 1N5309 overhere.
The J509 is also not on stock, so if the currentregulator diode could be added would be nice. I am not in a hurry to receive the boards....
I will try to get samples from Vishay.
Thanks, Loek
Indeed, and regular suppliers don't sell the 1N5309 overhere.
The J509 is also not on stock, so if the currentregulator diode could be added would be nice. I am not in a hurry to receive the boards....
I will try to get samples from Vishay.
Thanks, Loek
Hi all,
Thanks for the kind remarks about my layout, and once again applause for all Mark's effort and capital outlay to bring this project to life from a mere discussion thread
Before everyone starts building just a few notes that I need to stress that are not in the PDF guide I've posted here 3 months back.
- VR2 is positioned a bit high up close to the driver heatsink. This is still sufficient for the original Krell sink that didn't cover the entire package area, but for those wishing to cover all the way down may have to mill out a notch for it to fit.
- The film caps provided for are for the types that expand in length, not width, at higher values (4.5mm wide), so make sure the ones you buy will fit since many caps like Vishay MKP1837 series' values expand in width. The film decoupling caps don't have to be 100nF of course, 10nF should also work. Just make sure that they aren't the only supply caps on board or they could cause oscillation.
- Since the bottom two axial caps are covering the bottom mounting holes, naturally they should be soldered in from the top after mounting. The size provided for were intended for Solen 1uF 400V or Mundorf M-CAP 1uF 400V.
- The 62pF's are placed in front of the predriver transistors, so if buying small heatsinks make sure they won't interfere with the caps' positions e.g. the small "foldover" types. The design intention was for a thin sheet of aluminium to be used for all four, so that may be the easiest instead of individual ones.
- If individual sinks are used; only two of the four cascaded ones should need sinking, so start off with nothing and then add if you feel it's needed instead of going through unnecessary effort.
- If all the on-board capacitance provided for is used (4x 1000uF Panasonic FC will fit besides the other smaller sizes&values), and even more so if the power jumpers are replaced with resistors for improved filtering, there is likely to be a noticeable turn-on thump. For those using an additional small resistor in series with the entire board i.e. drivers included it will be even more. I'd suggest building and starting it up without any capacitance at all, and then progressively add them beginning with the 220uF and film caps.
- Those wishing to experiment without making excessive modifications can try adding a 100uF 50V cap in parallel with the zener diodes.. they will cause thump though.
- The amp should work OK at lower supply voltages, but for optimal performance they should be >42V. This is because of the 39V zeners used for the LTP's resistor current sources. Try to keep it between 48-52V voltage though. There was some confusion over original KSA100's intended values since it depends on which mains it runs on i.e. 220-220V or 110-120V.
- If the DC offset seems stable, try bypassing the feedback caps with jumper J3. No cap is after all better than the best Black Gate. FIRST MEASURE THE OFFSET BEFORE CONNECTING THE SPEAKERS!
Please comment on anything you've encountered that would have made construction easier; there's a possibility of a new production run where I can try to address it in the layout.
Also, since many of the KSA100 builders would be KSA50 veterans, comments on the differences would be welcomed.
Thanks for the kind remarks about my layout, and once again applause for all Mark's effort and capital outlay to bring this project to life from a mere discussion thread
Before everyone starts building just a few notes that I need to stress that are not in the PDF guide I've posted here 3 months back.
- VR2 is positioned a bit high up close to the driver heatsink. This is still sufficient for the original Krell sink that didn't cover the entire package area, but for those wishing to cover all the way down may have to mill out a notch for it to fit.
- The film caps provided for are for the types that expand in length, not width, at higher values (4.5mm wide), so make sure the ones you buy will fit since many caps like Vishay MKP1837 series' values expand in width. The film decoupling caps don't have to be 100nF of course, 10nF should also work. Just make sure that they aren't the only supply caps on board or they could cause oscillation.
- Since the bottom two axial caps are covering the bottom mounting holes, naturally they should be soldered in from the top after mounting. The size provided for were intended for Solen 1uF 400V or Mundorf M-CAP 1uF 400V.
- The 62pF's are placed in front of the predriver transistors, so if buying small heatsinks make sure they won't interfere with the caps' positions e.g. the small "foldover" types. The design intention was for a thin sheet of aluminium to be used for all four, so that may be the easiest instead of individual ones.
- If individual sinks are used; only two of the four cascaded ones should need sinking, so start off with nothing and then add if you feel it's needed instead of going through unnecessary effort.
- If all the on-board capacitance provided for is used (4x 1000uF Panasonic FC will fit besides the other smaller sizes&values), and even more so if the power jumpers are replaced with resistors for improved filtering, there is likely to be a noticeable turn-on thump. For those using an additional small resistor in series with the entire board i.e. drivers included it will be even more. I'd suggest building and starting it up without any capacitance at all, and then progressively add them beginning with the 220uF and film caps.
- Those wishing to experiment without making excessive modifications can try adding a 100uF 50V cap in parallel with the zener diodes.. they will cause thump though.
- The amp should work OK at lower supply voltages, but for optimal performance they should be >42V. This is because of the 39V zeners used for the LTP's resistor current sources. Try to keep it between 48-52V voltage though. There was some confusion over original KSA100's intended values since it depends on which mains it runs on i.e. 220-220V or 110-120V.
- If the DC offset seems stable, try bypassing the feedback caps with jumper J3. No cap is after all better than the best Black Gate. FIRST MEASURE THE OFFSET BEFORE CONNECTING THE SPEAKERS!
Please comment on anything you've encountered that would have made construction easier; there's a possibility of a new production run where I can try to address it in the layout.
Also, since many of the KSA100 builders would be KSA50 veterans, comments on the differences would be welcomed.
As suggested by Mark :
anyone interested in a tag team approach for the 1N5309 current reg. diodes ?
Mark,
i can't live without a set of the Goldy Locks, what's the paypal figure to go to Cinerama ?
Pierre,
any better than this board design and i'll pack my gear and come live at your place.
anyone interested in a tag team approach for the 1N5309 current reg. diodes ?
Mark,
i can't live without a set of the Goldy Locks, what's the paypal figure to go to Cinerama ?
Pierre,
any better than this board design and i'll pack my gear and come live at your place.