Paramount Soft Start upgrade for a Paramour II

Natural Sound · 4701

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Offline Natural Sound

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on: September 10, 2013, 05:01:08 AM
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.



Offline saildoctor

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Reply #1 on: September 10, 2013, 05:34:43 AM
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.

Kerry Sherwin

45 Paramounts, 6SN7 Extended FPIII, OC3 regulated Seduction
Blumenstein Orca Deluxe / 2x Orca Subs
VPI Classic / ADC CD-100x


Offline Paul Joppa

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Reply #2 on: September 10, 2013, 07:14:43 AM
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 Joppa


Offline Paul Birkeland

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Reply #3 on: September 10, 2013, 07:22:31 AM
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

Paul "PB" Birkeland

Bottlehead Grunt & The Repro Man


Offline Natural Sound

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Reply #4 on: September 10, 2013, 03:28:06 PM
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.



Offline Grainger49

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Reply #5 on: September 11, 2013, 02:02:00 AM
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:


(https://forum.bottlehead.com/proxy.php?request=http%3A%2F%2Fi244.photobucket.com%2Falbums%2Fgg7%2FGrainger49%2FBottlehead%2520Equipment%2FPNewIron1_zps8b62accd-1.jpg&hash=538b0f0ee5b0f1dd477234709302c8195a258f7c)



Offline Natural Sound

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Reply #6 on: September 11, 2013, 09:09:06 AM
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.



Offline Grainger49

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Reply #7 on: September 11, 2013, 09:48:55 AM
Sent!



Offline najo49

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Reply #8 on: September 12, 2013, 06:32:08 AM
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.

Jann Olsen, [email protected].  Lowther medallion 2 with pm2a./ extended foreplay lll,/EROS phono /Grado ref/ SOTA star Vacuum SME V, /  45 amp direct coupled,c4s,mQ nickel  / paramour  2a3 w MQ iron /Original SEX monos /Jena Cables /heathkit wm6a/ proAc Tablette 50 sig , with push pull


Offline Grainger49

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Reply #9 on: September 12, 2013, 07:42:52 AM
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.
« Last Edit: September 14, 2013, 02:22:31 PM by Grainger49 »



Offline Jim R.

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Reply #10 on: September 14, 2013, 12:29:06 PM
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

Jim Rebman -- recovering audiophile

Equitech balanced power; uRendu, USB processor -> Musette DAC -> 5670 tube buffer -> Finale Audio F138 FFX -> Cain and Cain Abbys near-field).

s.e.x. 2.1 under construction.  Want list: Stereomour II

All ICs homemade (speaker and power next)