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KTA-HiFi ST-70 Driver PCB (regular now in stock)
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Geek
KT88


Joined: 21 Oct 2007
Posts: 1112
Location: Chilliwack, BC

PostPosted: Fri Oct 30, 2009 8:14 pm    Post subject: Reply with quote

PM me your email. I'll send it to you.

Cheers!
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Fine wine comes in glass bottles, not plastic sacks. Therefore the finer electrons are also found in glass bottles.
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dannyr



Joined: 30 Mar 2009
Posts: 8

PostPosted: Sun Nov 01, 2009 3:30 pm    Post subject: Reply with quote

Okay so the board parts numbering is okay. We just have to space the board away from the chassis using the plastic spacers that you have provided. Thanks

Are B+2 and B+4 the place marked 380v on the board and B+1 and B+3 are 250v? Did you have to adjust the recommended 4.7/49.9k resistor values much in the power supply with a gz34 to have acceptable voltages? What is the range that would be okay?

Finally, how much capacitance in the power supply would be to much after the choke? I'm trying to picture how to do the two separate 50/50uf stages that are recommended for each channel. I have a punch so I could even use two multi section JJ caps with clamps to accomplish it and going 100/100 wouldn't be that big of a deal.

Any input would be greatly appreciated.

Thank you.
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Geek
KT88


Joined: 21 Oct 2007
Posts: 1112
Location: Chilliwack, BC

PostPosted: Sun Nov 01, 2009 11:29 pm    Post subject: Reply with quote

dannyr wrote:
Okay so the board parts numbering is okay. We just have to space the board away from the chassis using the plastic spacers that you have provided. Thanks


Cheers!

Mind the heater connection near the 12AX7 too ;-)


Quote:
Are B+2 and B+4 the place marked 380v on the board and B+1 and B+3 are 250v? Did you have to adjust the recommended 4.7/49.9k resistor values much in the power supply with a gz34 to have acceptable voltages? What is the range that would be okay?


*checks his schematics and board*

I'm not familiar with the designations... >_>

I jumped the two +250V together and then the +380 together and fed them 4.7K and 47 K with the 5U4 rectifier. You may need 5.6K/56K or 6.8K/68K for a GZ34.

Quote:
Finally, how much capacitance in the power supply would be to much after the choke?


The typical ST-70 choke isn't that big, so I'd be careful. Use what you have and if you're not satisfied, go a little larger.

Personally, I think the supply would do much better with a Hammond "159S" for improvements.

HTH

Cheers!
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dannyr



Joined: 30 Mar 2009
Posts: 8

PostPosted: Mon Dec 14, 2009 9:33 pm    Post subject: Reply with quote

Geek, I just wanted to thank you for all the help. I got the amp going and it's really good sounding so far and it only has about 10 hours on it. I tried a few coupling caps and believe it or not liked CDE polyesters with it the most. I wanted a full snappy vintage sound. Maybe I have no taste. haha.

The power supply resistors ended up being 6.8k and 61k with a gz34 for 376/251volts. It's also dead silent without anything playing so you did great on the layout:).
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Geek
KT88


Joined: 21 Oct 2007
Posts: 1112
Location: Chilliwack, BC

PostPosted: Mon Dec 14, 2009 11:57 pm    Post subject: Reply with quote

Great to hear!

I'll pass along the congratulations on the layout to the PCB guy.

Snappy vintage sound, eh? How about 716P polyprops? Available at AES.

Cheers!

PS - can you post a couple pics of your amp and board?
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dannyr



Joined: 30 Mar 2009
Posts: 8

PostPosted: Wed Dec 16, 2009 3:11 am    Post subject: Reply with quote

I'll have to borrow a camera etc. I have some 716's around that I can swap in but the CDE Polyesters are actually doing pretty well for now at least.
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jerkbag



Joined: 31 Jan 2010
Posts: 6

PostPosted: Tue Mar 09, 2010 9:59 am    Post subject: Reply with quote

Would anyone who has this installed be willing willing to post a photo (from the wired / underside)? It would be a great reference.
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battradio
KT88


Joined: 10 Mar 2009
Posts: 323
Location: near ST.Louis MO.

PostPosted: Thu Jun 17, 2010 5:14 pm    Post subject: Reply with quote

Hi Geek any of these left and postage for two to 62002 .
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Geek
KT88


Joined: 21 Oct 2007
Posts: 1112
Location: Chilliwack, BC

PostPosted: Thu Jun 17, 2010 10:05 pm    Post subject: Reply with quote

PM sent.

I forgot to mention that the price as of June 1st went to $28.50/ea., due to a new agreement with KTA HiFi.

Cheers!
_________________
-= Gregg =-
Fine wine comes in glass bottles, not plastic sacks. Therefore the finer electrons are also found in glass bottles.


Last edited by Geek on Thu Jul 29, 2010 2:28 am; edited 1 time in total
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Geek
KT88


Joined: 21 Oct 2007
Posts: 1112
Location: Chilliwack, BC

PostPosted: Thu Jul 29, 2010 2:27 am    Post subject: Reply with quote

I still have "Ooops" boards left for the steal-of-a-deal price of $15.00 USD/ea.

All they need are some insulating washers (supplied by me), as the pads touch and there's a non-critical reversal of the grid leak/grid snubber on the input.

Cheers!
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Fine wine comes in glass bottles, not plastic sacks. Therefore the finer electrons are also found in glass bottles.
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Ty_Bower
KT88


Joined: 21 Mar 2007
Posts: 1147
Location: Newark, DE

PostPosted: Thu Jul 29, 2010 6:19 am    Post subject: Reply with quote

Geek wrote:
The typical ST-70 choke isn't that big, so I'd be careful. Use what you have and if you're not satisfied, go a little larger.

Personally, I think the supply would do much better with a Hammond "159S" for improvements.


Like this Hammond 159S?


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"amazingly, with properly soldered wires, GNDing and wire dressing, the humm has disappeard despite components mounted in very close proximity."
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Geek
KT88


Joined: 21 Oct 2007
Posts: 1112
Location: Chilliwack, BC

PostPosted: Thu Jul 29, 2010 4:19 pm    Post subject: Reply with quote

YEAHHHH! Dat's what I'm talking about!

Mo iron!

Cheers!
_________________
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Fine wine comes in glass bottles, not plastic sacks. Therefore the finer electrons are also found in glass bottles.
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