Paramount Soft Start upgrade for a Paramour II

[Natural Sound]

How difficult would it be to install a Paramount Soft Start upgrade into a Paramour II? Also, does the HV delay feature work for the power tube or is it just for the driver? One more thing. Is the second triode in the 5670 used for anything like maybe a shunt regulator?

If the question of gain comes up, yes, I have plenty of gain. So much so I had to use a heavy hand with the padding resistors in my FPIII. I understand that the 5670 can help in that area as well.

 

[saildoctor]

It delays the HV just for the driver, and it does use the 2nd triode for a regulator.  It does need some real estate around the driver tube socket for the board and its terminal strips.  I don't know if the HV of the Paramour II is compatible though.

 

[Paul Joppa]

It will work fine. The Paramour II power transformer was specified from the beginning to accommodate exactly this change. We don't have a manual specifically for this, however.

 

[Paul Birkeland]

The soft-start feature won't be of any real benefit in the Paramour II, but you can still use it without harm.

The kit will work as-is on the Paramour II, but tweaking it a bit for more compliance couldn't hurt.  I would change the 330K R2(A) to a 200K/3W resistor, and the two 149K resistors to 140K.

This will drop the regulated voltage down to ~283V instead of 300V, and rebias the first C4S for the lower voltage.  In the Paramour, the string of Zener diodes won't be necessary.

I don't think the installation is all that difficult overall, but if you run into trouble, it will be difficult for us to support the modification since we have never performed it ourselves.
-PB

 

[Natural Sound]

Thanks guys. It hardly seems worth the effort.

I still might still explore the possibility of using a 5670 driver due to its lower mu. I'm on a quest with the less is more theory as my guide.

 

[Grainger49]

I posted a How To on the old forum.  Dan et. al. sent a Paramour II manual and I wrote up how to change the 12AT7 to a 76.  It has the same shape as the 2A3, has a lower Mu, is a single triode and sounds wonderful, at least to my taste.

I can PM the instructions if you are interested.

Here is a shot of one of my Paramours:

 

[Natural Sound]

I posted a How To on the old forum.  Dan et. al. sent a Paramour II manual and I wrote up how to change the 12AT7 to a 76.  It has the same shape as the 2A3, has a lower Mu, is a single triode and sounds wonderful, at least to my taste.

I can PM the instructions if you are interested.

Yes please. I'm interested.

 

[Grainger49]

Sent!

 

[najo49]

So let me get this clear. You change a 12at7 triode for a 5670 which is not a triode. I do not see how this is possible,w/o changing the circut drastically.

 

[Grainger49]

The 5670 is a dual triode like the 12AT7.  In Paramour IIs one half of the dual triode is unused.  In the Paramount one half of the 5670 is used as the driver the other half is a voltage regulator.

 

[jrebman]

Hey Tom,

I asked this same question a few weeks ago and am planning on doing it when I build the paramour II 2a3s. I do believe there will be a nice difference with having the driver stage shunt regulated, so even though the soft start (and zeners) will not be of any real use in the cap coupled paramour II, the shunt regulated driver will probably be a nice touch -- call it half an sr-45 if you want to think of it that way. And the PT2 does have enough current capacity for the extra current required for the shunt regulation -- which was my question earlier.

-- Jim