Paramount 300Bs - What Next?

[Gerry E.]

Hi:

I acquired my already-built Paramount 300Bs about a year ago.  They already had upgraded caps installed (Mundorf and V-Caps).  Shortly after, I had the Soft-Start kit installed.  Then came Ericsson 396A/2C51s and  EML solid-plate 300Bs.  A few months ago, a friend (99%) and I (1%) installed the Magnequest upgrade iron (BH-5 all nickel output transformers and BH-7 plate chokes).

Originally, I wanted to keep the amps with 300B output tubes, but now I

[Paul Joppa]

The BH-5 and BH-7 will work well with either tube.

The choke that is reconfigured is the filament choke, behind the power transformer, not the plate choke or the output transformer.

[Gerry E.]

I was going to let this thread die because of my silliness in confusing the plate and filament chokes.  However, I have nothing to lose, so let

[Paul Birkeland]

Hello Gerry,

Considering you bought the amps built, it does not seem very silly to mix up the plate choke and filament choke.

Yes, roatating the 4-pin socket is tough if you stick with the stock socket.  There is a teflon socket with a black retainer ring that would let you rotate everything, you'd just have to be careful about getting things hooked back up properly. 

As far as deadening the chassis, there is a ton of iron on there that deadens things pretty well, though I am familiar with the noise the rocker switch makes when you switch the amp on.  I have seen some people go to the hardware store and buy some 1" x 1" lumber, cut them to 2", and glue them into the corners of their bases, then drill holes in the corners of the chassis plate and screw the plate into the base.

This always seemed overkill to me on something that weighs as much as the paramount. 

Otherwise, you could get something like Dynamat and cut it into long strips, sticking them all the way around the edges, but I think ultimately you'll just end up with a bit of a mess.

-PB

[Paul Joppa]

The main (technical) problem with sheet damping materials is that their effectiveness is a strong function of temperature. The industrial materials are often specified for a particular temperature range; the "consumer" stuff less frequently. Bottom line, stuff that works well for speakers is not what you want on a hot chassis plate - it gets too gooey. You need something that is between hard and gooey at the operating temperature.

One might look for automotive (engine compartment) materials or heating-system materials for use with tube amps.

[Gerry E.]

Thank you PB and PJ (for both your current and previous reply).  I think I

[Paul Birkeland]

Hello Gerry,

Yes, that's the idea.

You can go for ceramic instead, which can be found here:

http://www.ebay.com/itm/1PC-4Pin-2A3-300B-274A-CMC-Ceramic-Gold-Tube-Socket-UX4-/251164502160?pt=Vintage_Electronics_R2&hash=item3a7a922890

Do note, the "upgrade" PCB that accompanies one of those sockets seems like a pretty bad idea, the heat from a 300B will cook and destroy a PC board pretty effectively, so I'd stay away from those.  I can also see that the ceramic sockets have lockwashers on them, which remedies the issue of the pin nuts loosening with the teflon sockets. 

You may also find that getting those 22 ohm resistors back in place is pretty tough.  You could consider replacing the 10 ohm wirewound pot with a 50 ohm 5w pot and omit the resistors (hum adjustment will be more touchy in this configuration).

-PB