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Old 13th February 2014, 06:03 PM   #1711
toobhed is offline toobhed  United States
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The two problems that I faced was the PSU jack whose two tabs I soldered were the wrong two of three tabs....after resoldering different tabs it worked great.

The other problem I had on the second monoblock was that the RCA input was shorting due to melted insulation....once I fixed that everything was fine...hope this helps a bit.
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Old 13th February 2014, 08:02 PM   #1712
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When I first built the ACA the PSU socket was the bit that caused me the most stress. The original build thread picture wasn't great and wiring the different legs was a matter of educated guess work. The picture is better now.

Even after that 6L6 and I exchanged about 13 emails and several pictures of my ACA trying to figure out why it kept blowing my PSUs.

It turned out that one of the legs on the PSU socket was loose and would rotate round when the case was knocked. The supply would short and bam. I went through 3 PSUs before we sorted it.

Last edited by Anima999; 13th February 2014 at 08:09 PM.
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Old 13th February 2014, 10:52 PM   #1713
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Sorry if this has been asked before but I searched and could not find my answer. I just purchased the PCBs since the kit is sold out and before I place my digikey order for parts I'd like to source the 2SK170. Which grade (gain??) should I be looking for? And do I need a matched pair? Or is that just for push/pull or other applications with multiple 2sk170s per channel.
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Old 13th February 2014, 11:30 PM   #1714
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no matched

2SK170BL is most adequate

if going to DiyA Store LSK - take LSK170B , preferable , being same current (6-12mA ) grade

or just take anything they have
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Old 14th February 2014, 07:12 AM   #1715
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Here is what Papa Pass told me a while ago:

By the usual standards the D version would be the most desirable, and probably would command a premium. The B through D and most of the A would not be a problem for the ACA, and a slight adjustment would allow down to the 2.5 mA figure without problems.

Most of my projects would want a B or C grade as most desirable, but it’s not a big deal.
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Old 14th February 2014, 03:32 PM   #1716
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Awesome thanks guys, I'll see if anyone in the buy/sell forum has a few to sell. Don't need the big lot that store sells.
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Old 14th February 2014, 03:50 PM   #1717
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if you start with anything here , soon you'll search for more
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Old 14th February 2014, 03:52 PM   #1718
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Default guesstamate

How about j310 for a starter in this circuit??!!
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Old 14th February 2014, 06:19 PM   #1719
Variac is offline Variac  United States
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Huge lot of JFETS coming to the diyAudio store.


Quote:
Originally Posted by disorder View Post
Awesome thanks guys, I'll see if anyone in the buy/sell forum has a few to sell. Don't need the big lot that store sells.
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Old 14th February 2014, 06:38 PM   #1720
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Quote:
Originally Posted by sandyhooker View Post
How about j310 for a starter in this circuit??!!
309 or 310

sort proper source resistor to have no more than 10mA though Jfet and proper biasing of output mos

edit - it seems proper starting value for J310's Rs is in range of 680R

start biasing with bias pot's wiper cranked to zero
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Last edited by Zen Mod; 14th February 2014 at 06:44 PM.
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