Gas tube regulation

[gstew]

Part of my goal in my own build was to add the 0C3 but keep it all within my existing Seduction chassis with the same tranny.  Well... actually I think if I had to explain why I needed another box to power the first box my housemate may have tried to smother me as I sleep.  Ha!  That's great that you're going for it - bet it will be super quiet!

LOL!

My housemate is a saint about my hobbies... and you'd agree if you saw how much my different projects and sprawling stereo have taken up space in our home!

We'll see about the quiet. This is for my smaller, downstairs system where it shares a shelf with the turntable. Whenever I get the main, upstairs system going again, the phono stage has it's own stand and there's plenty of room for the full-sized Seduction or larger.

Part of the reason for the repackaging is to fit it into a space.  only 6" wide or so... but also, it sits next to my computer music server. While I've done a lot of mods to that to reduce conducted & radiated EMI/RFI, it will be only a few inches away. I know I may have to power down the server to play records... I can live with that. It may be I only have to power down the highest-polluting item, the small screen, which has its own supply and can be powered off by itself. But part of the reason for the re-boxing is to better shield the whole thing.

One issue I'm grappling with is how to deal with mechanical vibrations. The cast ally boxes ring... they'll get damped. Then I'm rebuilding the Seduction active circuit on a piece of Corian... that will get damped too and it'll have a suspension using Herbie's Audio Product material. It's somewhat of an experiment, but a fun one... and having your gas-tube regulator upgrade to go in at the same time is just another excuse for doing it! Thanks for publishing that!


Greg in Mississippi

 

[Paul Joppa]

...So I think I'll go the route of the AMTRANS polyprops from Parts Connexion... parallel 2 5600pf for the .0112uf value and 4 8200pf for the .033uf value. I'll get a few extra of each value so I can make 1% combos. ...

Another way to go is to use 0.030uF and 0.010uF caps, changing the resistors 66.5K to 75K and 9.64K to 10.7K. Precision caps are often available in only a few values, but 0.010uF is usually one of them, and you can parallel three of them to get 0.030. Sometimes you get a price break for 10 caps, so you throw out the worst two and sort the rest. The target is actually 0.0297 and 0.01011, and 73.7K, as long as you're sorting...

 

[gstew]

Paul,

Thanks, that's very helpful. It'll give me some flexibility in cap selection.

I'll be using 6N1Ps... I assume that these values don't change, but is the change of the RIAA termination resistor from 1M to 500K affected?

Also, I have .033uf and .011317uf as the nominals for the stock Seduction RIAA values... those right?

Again, and as always, thanks!

Later!

Greg in Mississippi

 

[Paul Joppa]

Paul,

Thanks, that's very helpful. It'll give me some flexibility in cap selection.

I'll be using 6N1Ps... I assume that these values don't change, but is the change of the RIAA termination resistor from 1M to 500K affected?

Also, I have .033uf and .011317uf as the nominals for the stock Seduction RIAA values... those right?

Again, and as always, thanks!

Later!

Greg in Mississippi

Yes, I'd change the load resistor to compensate for the 6N1P's higher plate resistance.

Take 60pF off of C2 (0.011257uF) - 50pF for Mr. Miller, and 10pF for wiring, socket, etc. capacitance. If you need to be REALLY picky! I get 66pF total for the 6N1P, according to the US Svetlana data sheet - net 0.011251.