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Old 29th January 2007, 10:31 PM   #1111
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Quote:
Originally posted by AR2
I got my boards. Really, really, really nice work.
Thank you Mark

Got mine too. Just beautiful!

Blessings, Terry
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Old 29th January 2007, 11:04 PM   #1112
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Glad you guys like em!! What is a J509??
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Old 30th January 2007, 12:27 AM   #1113
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Found the boards in my mailbox today. Mailman really tried to bend them in half but the boards were stronger than he was. They look GREAT! Now if I can just find enough really big heatsinks.... Thanks for the effort, Mark!

Bob G.
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Old 30th January 2007, 12:58 AM   #1114
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"Glad you guys like em!! What is a J509??"

Isn't it an alternate current limiting diode for D5 & D6?
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File Type: pdf j509.pdf (35.4 KB, 137 views)
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Old 30th January 2007, 01:51 AM   #1115
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Great! The J 509's are half the price and they offer a good quantity discount too. Are you guys sure they will work in this application?

Mark
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Old 30th January 2007, 02:24 AM   #1116
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Default J509

The J509 POV is only 50 volts the 1N5309's POV is 100volts
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Old 31st January 2007, 09:12 PM   #1117
AVWERK is offline AVWERK  United States
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Thanks Mark & PH

Very very nice boards and thick traces to boot

Thank you sincerely!
Now where's that Mouser catalog...

Regards
David

(Mark, which mosfet package did you use? BTW)
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Old 31st January 2007, 09:18 PM   #1118
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(Mark, which mosfet package did you use? BTW)
I've tried all three and you can use what ever you fancy. The 4 pin dip versions do dissipare a bit more heat though than the small plastic version. I have the SMT version in my amp now and no problems. They all will work just fine.

Mark
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Old 1st February 2007, 06:59 AM   #1119
PWatts is offline PWatts  South Africa
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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.
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Old 1st February 2007, 08:49 AM   #1120
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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.
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