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Old 21st February 2014, 11:54 PM   #1181
DQ828 is offline DQ828  Australia
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Default AP Linkage

I want to put the AP filter in the HP section & I assume I should do this by installing a link (see attached) between JP8Pin 1 to the AP IN & then from the AP OUT to the JP8 pin 2, is that correct?

In the AP filter & the EQ filters there are ground points on the inputs & outputs but I dont understand why. How should they be used. Is the idea to run a ground wire from say near JP8 for the AP so that the AP ground is closely linked to the HP circuit section?
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Old 22nd February 2014, 12:22 AM   #1182
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That looks correct. Ideally you'll take your signal and return out together. Since the board's ground plane connects all grounds you can probably get away with just running a signal wire. It wouldn't hurt to carry the ground back from both all pass connections twisted with the signal lead. If you get any hum do this and terminate the grounds at the HP out ground pin.

Header connections with ground were included in case you were cascading all pass sections on two different boards.
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Old 22nd February 2014, 05:54 AM   #1183
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Quote:
Originally Posted by BobEllis View Post
That looks correct. Ideally you'll take your signal and return out together. Since the board's ground plane connects all grounds you can probably get away with just running a signal wire. It wouldn't hurt to carry the ground back from both all pass connections twisted with the signal lead. If you get any hum do this and terminate the grounds at the HP out ground pin.

Header connections with ground were included in case you were cascading all pass sections on two different boards.
Thank you
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Old 24th February 2014, 08:47 AM   #1184
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Bob

The PSU (15V) boards have trimmer resistor locations marked as P1 & P2 but they are not in the BOM? are they required?

Also in the BOM (that I have) 2 resistances are give for R11 & 13, from what I can surmise I should use the 2K for the 15V & not the 3.3K, is that correct.
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Old 24th February 2014, 09:25 AM   #1185
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The trimpots are there for those who want to get exactly the same rails or have some adjustability. Use 10k and 3K3 and you'll be able to adjust a bit either side of 15V. Use 2K and you'll be within a few mV of 15V.

In case you didn't guess, trimpots weren't included in the kits as a cost saving measure.

Last edited by BobEllis; 24th February 2014 at 09:27 AM.
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Old 7th March 2014, 11:59 AM   #1186
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I still have 2 positive and 2 negative PSU boards, build and tested, that are gathering dust. Anyone interested?
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Old 19th April 2014, 12:41 AM   #1187
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Default PSU Issue

I have finally got to testing the PSU before connecting it to the Crossover and have run into a problem. On the + side I am getting 15V on the out but on the - side I am only getting -3.96v on the out I have attached a couple of photo's in the hope you might be able to give me an idea of where I have gone wrong or what/how I should test to work out where the problem is. Both sides are getting 18v ac on the input.

The boards and parts where sitting around in Greece for many years & where a little bit worse for wear (oxidization etc) when I got them, I tried to clean them up but was a little concerned I may have issues. Of course this problem many have nothing to do with that.
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File Type: jpg PSU RQ 01.jpg (292.0 KB, 102 views)
File Type: jpg PSU RQ 01_2.JPG (776.2 KB, 96 views)
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Old 19th April 2014, 12:55 AM   #1188
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Sounds like you have a failure to start on the negative side. Try increasing R19. Jens had good results with 1.2-1.5K. I just omit R19 and R4 all together and haven't been able to hear a difference.

In theory cleaner power to the reference will make the regulator perform better, but I think the LM4040 is stable and quiet enough with a 1uF cap across it that it doesn't matter. If you want to clean up the power without using the R4/19 references to the output, you can substitute a current regulating diode for R3 and R18 and omit R4 and R19. You don't need much current with an LM4040, a couple mA is plenty. For example you can use http://www.mouser.com/ProductDetail/...252bWWtpFG4%3d

Hope this helps and keep us posted on your results.

Last edited by BobEllis; 19th April 2014 at 12:59 AM.
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Old 19th April 2014, 01:07 AM   #1189
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Bob

Thanks for the quick response I try omitting R19 & R4 tonight and see how it goes.

David
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Old 19th April 2014, 01:28 AM   #1190
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Well I couldn't wait (bugger the mowing) so I cut out R19 on the negative side only, as it is the problem side & I now have -1.99V on the out. Both R4 & R19 were 950ohms. with R4 still in place the + side is giving 15.15v out.
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