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Old 31st October 2009, 04:19 AM   #61
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The LM317/337 are running quite cool and don't need much heatsinking; the MJE devices need a lot though.

When using 6-40 screws, you can tap through hole plated mounting holes in the board without a need for additional nuts.

While mounting LM317/337 and MJExxx on a same heatsink, at least one of the devices need to be isolated. I used the pad on LM317 and mounted MJE directly, using 4-40 and 6-40 machine screws respectively.
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File Type: jpg ph8.jpg (193.4 KB, 1398 views)
File Type: jpg ph9.jpg (178.7 KB, 1336 views)
File Type: jpg ph10.jpg (191.3 KB, 813 views)
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Old 31st October 2009, 04:46 AM   #62
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Please note position of 1k and 200R resistors. A trimpot can be installed in place of 200R for output voltage adjustments. Also, since J511 is hard to get, I added pads for Motorola 1N5314 which is a good substitute (K indicates Cathode)

I use Nichicon FG 100/25 for all small bypass caps, I'm not sure yet, but they may be actually better than BG STD here. You may also notice that this time I didn't install the controversial cap across current source, instead, I have quick install sockets and be doing some comparisons

When using PS board with phono section attached, C11/12 does not need to be installed as it installs in phono section instead.

For a free standing, separate PS only board, those caps are needed.

Using Variac, I checked what is the minimum voltage on main filter caps to still support 15V output: it looks like anything below 17.3V is already too low.

In case you have transformer with secondaries too low, simple adjust with R7/R8 for lower output voltage; OPA627 will work fine with 12V rails as well.

This concludes PS assembly, I will follow with phono board soon.
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File Type: jpg ph11.jpg (190.2 KB, 827 views)
File Type: jpg ph12.jpg (192.4 KB, 788 views)
File Type: jpg ph13.jpg (195.9 KB, 507 views)
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Old 31st October 2009, 05:14 AM   #63
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Hi Peter

do you have a cost for the boards plus parts excluding black gate caps, and a time schedule for its release??

Luke
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Old 31st October 2009, 06:52 AM   #64
jormajj is offline jormajj  Finland
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Peter, in an earlier post you say 2 PSUs is better than 1. Would that mean also 2 phono PCBs or are the power tracks easy to separate ?
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Old 31st October 2009, 02:02 PM   #65
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You will need two PS boards, but could do with only one phono board by cutting it in half. The layout allows separate wire feed with dedicated bypass caps. I will be presenting it soon.
However, constructions wise, it's easier to simply populate one side only (phono) on each complete board.



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Originally Posted by audiojoy View Post
do you have a cost for the boards plus parts excluding black gate caps, and a time schedule for its release??
The boards are $40/set, email me for parts cost.
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Last edited by Peter Daniel; 31st October 2009 at 02:22 PM.
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Old 1st November 2009, 12:34 AM   #66
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This is how I install resistors.

Price of Vishays is proportional to resistance value, and 330K resistor will cost more than $30pc, so I use nude Vishays only for 1k6 and 3k3.

Besides, I had very good results with Caddocks as well, especially in feedback and input shunt positions.

1k6 and 330K fit very nicely in a bottom layer, between the pins of op amps. I normally do not use 47R output resistor and take the signal directly from the second chip.

You will also see BG N for 10uF cap, short pin on +.
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File Type: jpg ph20.jpg (172.9 KB, 606 views)
File Type: jpg ph21.jpg (194.1 KB, 681 views)
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Old 1st November 2009, 12:49 AM   #67
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The caps go next, and here you see Teflon V-Caps. I didn't even consider using anything else in a phono stage of such caliber, but I can imagine that MIT RTX or Mundorfs will work almost as good.
BTW, you will see "R" next to cap's pads, that indicates red lead, since those caps are directional according to manufacturer.

The filter caps (BG STD 100/16) have been moved from PS section in here. I use 2 sets of caps only if PS and phono board are separated by umbilical cord.
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File Type: jpg ph24.jpg (198.2 KB, 625 views)
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Old 1st November 2009, 01:14 AM   #68
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All that is left is to supply power to phono board and we do it with 4 jumpers that can be put either in top or bottom layer.

And that's all, the assembly is completed.
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File Type: jpg ph25.jpg (193.8 KB, 630 views)
File Type: jpg ph30.jpg (197.0 KB, 558 views)
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Last edited by Peter Daniel; 1st November 2009 at 01:42 AM.
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Old 1st November 2009, 11:43 AM   #69
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Peter,

What are the pluses and minuses of using the 47R resistor on the output? I have mine up and running and it sounds very good so far. Still need to play around a bit to see if I can minimize some hum.
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Old 1st November 2009, 03:02 PM   #70
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Without resistor, the sound usually becomes more transparent. OTOH, that resistor terminates the output and acts as protection as well, so it's worth experimenting if the risks are worth the gains
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