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PostPosted: January 15th, 2023, 1:32 pm 
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Joined: March 12th, 2013, 11:12 am
Posts: 738
Whats interesting is that the RFI is very sensitive to where I attach the gound wire from the tonearm. No attachment, the RFI comes in crystal clear. Attached to the back of the phono stage it is reduced ~6db, but attached to the outboard PS is drops another ~3db or so.

I'll be around tonight or tomorrow night but out most of the day.





David McGown wrote:
Pete,

Funny about the radio on your phonostage. You might get a different station if you change the cartridge loading.

I read a suggestion about using clamp-on ferrite beads on the tonearm cable at the input to the preamp. I tried it, and it seems to reduce the volume of the rectified RF.

If you would like the Kitsune back, let me know. I am tied up tomorrow afternoon, but could drop it by tomorrow evening or Monday if you are home. Really appreciate the loan, but I have to admit I have been tweeking my PassDIY Pearl 2 to get the best sound out of it. Did an output cap change (Wayne Colburn used a 22uF/50V Silmic bypassed with a 0.1uF PP (Wima or similar). I swapped in a 10uF/50V Wima MKS (Mylar) bypassed with a 0.1uF Wima polycarbonate and a 0.01uF Vishay 1837 PP (too tight for a teflon). Nicer sounding than the eCap.

David


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PostPosted: January 15th, 2023, 4:57 pm 
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Joined: February 28th, 2013, 1:19 pm
Posts: 923
Pete,

I can stop by tomorrow night, if that is OK. What time is good for you? You can reply via text or PM if you want.

Grounding is probably the main issue, need to find (create) a low impedance path to ground for RF. Of course, not much control one can have with a commercial product.

David


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PostPosted: January 16th, 2023, 8:41 am 
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Joined: March 12th, 2013, 11:12 am
Posts: 738
I should be around from the later afternoon on (3ish onwards). Just text me before you head over.

David McGown wrote:
Pete,

I can stop by tomorrow night, if that is OK. What time is good for you? You can reply via text or PM if you want.

Grounding is probably the main issue, need to find (create) a low impedance path to ground for RF. Of course, not much control one can have with a commercial product.

David


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PostPosted: January 16th, 2023, 9:49 am 
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Joined: February 28th, 2013, 1:19 pm
Posts: 923
TubeDriver wrote:
I should be around from the later afternoon on (3ish onwards). Just text me before you head over.


OK, Will do.


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PostPosted: January 16th, 2023, 1:30 pm 
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Joined: March 12th, 2013, 12:45 pm
Posts: 40
Location: Annapolis, MD
Hello David:

Could your share/post your specific BOM that you used? Some of your parts and chassis look neat.

David McGown wrote:

I picked up the Wayne's BA 2018 board and parts kit from the DIYAudioStore and finally built. Wayne Colburn, for those you do not know, is the preamp designer at Pass Labs. This was just a throwaway project to the DIY community, as both Wayne and Nelson Pass is prone to do. It is a DC coupled discrete opamp design, with JFET input (using Toshiba 2SK208 SMT JFETs), and BJTs for current sources and output stage. Just completed the build a couple days ago and it is breaking in on the system. It is possible to adjust the gain via the feedback resistor, the default is 3.7 with a 10K resistor, but I have set it at around 2.5 using a 22K resistor to better fit in with my overall gain structure (been using passive attenuators for years, all my amps have enough front end gain). I find the clarity and transparency to be better than my recent 12SN7 Aikido linestage, and the drive and control that the active gain stage results in my tube amplifiers sounding more solid and powerful. The problem I have found with passives is often a slight thinness or lack of body, although they can be very transparent. The new linestage is absolutely quiet and very detailed sounding, with an expansive soundstage and a hint of warmth (but not so much as to be a coloration).


_________________
"We are all inventors, each sailing out on a voyage of discovery, guided each by a private chart, of which there is no duplicate. The world is all gates, all opportunities."
Ralph Waldo Emerson


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PostPosted: January 16th, 2023, 2:21 pm 
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Joined: February 28th, 2013, 1:19 pm
Posts: 923
cport wrote:
Hello David:

Could your share/post your specific BOM that you used? Some of your parts and chassis look neat.



Well, outside of the linestage board and parts kit available at DIYAudioStore.com, and the ‘Designed by Mr K” 50K series attenuators I picked up on eBay, the rest of my project is from parts I had around. The power supply is a +/-15VDC power supply designed by Pete Millett for his LR Phonostage project. It is not a kit, but a board that he sells on eBay with a Schematic and BOM on his webpage. The enclosures are Hammond 1455 series extruded aluminum, 1455T1601 for the linestage and 1455Q2201 for the power supply. Source selector switch is a high quality Alco gold over silver contact dpdt toggle switches.

That is all I can do for now. Oh, keep with the design gain of 3.7, I preferred that over a reduced gain version.


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