Dumb question re ParamourII

[chrisby]

Would the Paramount soft start / revised driver circuit work for  ParamourII - if for no other reason than the reduced gain of driver?  I've always found the 12AT7 a bit too hair-trigger sensitive, particularly in combination with ForeplayII, and have never got around to dealing with it.

You know,  if it ain't broke, it's cause you haven't really used it.    or is that just me?   

[Grainger49]

It is to soften the startup voltage on the grid of the output tube (direct coupled configuration of the Paramount).  The Paramours are all capacitor coupled so the driver DC is not "seen" by the output tube grid.

If you want to limit the gain of a Paramour change the driver to a 76 like I did.  I have a writeup on the old forum and can send you either a word doc or a link to the post if you are interested.

Having an output tube and driver look like each other, ST tube shape, is cool!

[Paul Joppa]

I don't see any reason the "soft-start" board would not work. It adds shunt regulation of the driver, which is not part of the stock Paramour II, as well as switching to the 5670 tube and reducing the thump on startup. Note that the shunt regulation increases power supply current, so it is not applicable to thee Paramour I with the Hammond power transformer. Paramour II with the BH-2 power transformer is specified for the requisite current - that's actually one of the reasons we developed that transformer.

There are no instructions specific to the Paramour II, though the layout is similar since they use the same chassis plate.

Another feature of the soft start board is a trimmer to adjust the driver bias. An interesting possibility for systems with too much gain is to use a 12AU7 or 6CG7 driver, or even a 6SN7 with a socket change, which will reduce the gain quite a lot - 10dB or more. (The 12AU7 has the same pinout as the 12AT7 so would be easiest to implement.) How many unusable clicks of the Foreplay level control do you have? That will determine how much gain reduction will be useful without limiting the maximum gain unacceptably.

[chrisby]

Grainger:

thanks for the suggestion re 76 driver - I'm sure I remember you mentioning or even sending me the full details before, but IIRC the requisite surgery seemed more than I wanted to undertake at the time - of course something like the soft start circuit wouldn't be a 5 minute refit either.

Paul:

It is a Paramour II, so provided they all had the BH2 drop through power transformers, I'd imagine I'm safe on that account.

Actually the stock volume pots had been replaced with a cheapie Alps stereo control (I found dual mono controls to be even more frustrating) - the issue is this particular system is in a very small room, and with the output level of two of the sources in this system ( Jolida CD player and Yamaha FM tuner) even with FR drivers with sensitivity in the low 90s, I can barely get enough control at the beginning of the dial.  

One of my other amps (who of us has only one   ?) uses a Raytheon 5842 (WE417) driving  6CA7, a combination which I quite enjoy, and the improved linearity attributed to the 5670 sounds very interesting.

Anyways,  just some noodling thoughts

thanks all

Chris  

[4krow]

Chris,   I share your frustration with the amp that i own. It also uses a 12ax7. I was thinking more on the line of a series resistor, but it just has a bad feeling attached with it. Grainger had mentioned the tube swap(well, after 'surgery') as well. It may make the most sense. I am doing some other stuff to my amp, and this may just be the time.