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tpryan
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Joined: 04 Dec 2003
Posts: 1737
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 Posted: Wed Sep 10, 2008 3:42 pm Post subject: N72 Rev 3.1 Now Shipping! |
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Revision 3.1 of the N72 is now shipping with "slow rise" phantom power switching. Be careful not to mix up the BC184C transistors with the MPSA06 and MPSA56 transistors in the phantom circuit! Updated BOM, schematic and assembly instructions are now on line.
Please post all questions regarding Rev 3.1 changes in this thread. |
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KevinL
Joined: 10 May 2006
Posts: 18
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| Posted: Tue Sep 16, 2008 10:57 am Post subject: |
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I have an older (pre 3.0) N72. What does the "slow rise" phantom power switching fix? I'm curious because I had an AT4047 FET blow on me once using the N72. I don't know if it happened when phantom was applied or not.
Could a phantom power spike from the N72 cause this to happen? |
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tpryan
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Joined: 04 Dec 2003
Posts: 1737
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| Posted: Tue Sep 16, 2008 12:04 pm Post subject: |
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| Quote: | | What does the "slow rise" phantom power switching fix? |
It doesn't fix anything, it's a new feature that can reduce the pops and thumps heard when switching phantom without muting first. Switching phantom without muting is still bad practice, but the very slow rise and fall makes it less bad. |
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DWM
Joined: 21 Sep 2008
Posts: 1
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| Posted: Sun Sep 21, 2008 9:42 am Post subject: Value of C25? |
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| I recently built a ver 3.1 of N72. The only discrepency I found was C25 is listed in the BOM as 22uF/50V and on the schematic as 22uF/35V, but the kit came with a 47uF/50V capacitor (at least that is what was left over). I believe this is what the ver 3.0 used there (I built one of them too). Is it OK to use the 47uF, or should I get a 22? If not OK, would it be a good idea to change the one in the ver 3.0 board to 22? |
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tpryan
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Joined: 04 Dec 2003
Posts: 1737
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| Posted: Mon Sep 22, 2008 3:04 pm Post subject: |
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| Either the 47uF or the 22uF will work fine. The larger value gives no measurable improvement, so there's no need to match them. |
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j_gander
Joined: 16 Mar 2009
Posts: 1
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| Posted: Mon Mar 16, 2009 1:50 am Post subject: |
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I had the same discrepancy with C25 in my kit and one other small one as well. C15 on the BOM is listed as 470 uF/6.3 volts, but what I received was 470uF/10 volts. Is it safe the assume that this is a substitute?
Thanks for your help.
Jesse |
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tpryan
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Joined: 04 Dec 2003
Posts: 1737
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| Posted: Thu Mar 19, 2009 8:56 am Post subject: |
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| Quote: | | Is it safe the assume that this is a substitute? |
Yes. The BOM will be updated as time permits. |
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ghetto3jon
Joined: 04 Nov 2007
Posts: 42
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| Posted: Mon Oct 26, 2009 7:00 pm Post subject: |
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no sonic differences, i assume. can version 3.0 be easily tweaked to get slow rise phantom?
p.s., i thought all the SCA kits already had slow rise phantom...is 3.1 just "slower"? |
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tpryan
Site Admin
Joined: 04 Dec 2003
Posts: 1737
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| Posted: Tue Oct 27, 2009 7:43 am Post subject: |
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| Quote: | | no sonic differences, i assume. |
No, the only changes were to the phantom circuit. These have been shipping for more than a year, BTW.
| Quote: | | can version 3.0 be easily tweaked to get slow rise phantom? |
Nope.
| Quote: | | i thought all the SCA kits already had slow rise phantom...is 3.1 just "slower"? |
The new active circuit is 33 times slower than the old passive circuit. |
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Archmart
Joined: 02 Apr 2007
Posts: 52
Location: EARS Chicago
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| Posted: Sun Mar 07, 2010 4:52 pm Post subject: |
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Hey Hey!
It's been two and a half years since I last worked on my 5th of 8 kits (2 of each at the time). I'm about to resume and finish up one more J99 and two N72s.
The N72s are Rev. 3.0. I wonder if there's an upgrade path I should take before I put the work into these?
Please advise.
Thanks,
Archmart |
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