2a3 Paramount

[shelby1420]

Hey all, decided tonight for shits and giggles to change my Paramounts over to 2A3, both of them after turning them on ( abouut 10-15 seconds I get a pop  kimda like a cap charging up, is this normal??

[Paul Joppa]

Yes, it's normal - assuming I have interpreted your description correctly. The "soft-start"/5670 conversion kit eliminates that "pop". More significant, it allows you to adjust the driver bias for the best 2A3 operating condition.

There have been other approaches to optimizing that operating point, most notably a small resistor in series with the LED in the driver cathode (if adjustment is necessary). As a good approximation, the driver plate voltage should be close to 1/3 of the 2A3 plate voltage - this is what we specify in the kit.

The above only applies to the 2A3 (direct coupled) version.

[shelby1420]

Thanks Paul, I suspected as much, just wanted to be sure!!  Thinking of a few other things here..... assuming I like continue to like what I hear enough to keep 2a3 as apposed to the 300b what kind of differences/improvements/other will I notice if I do the magnequest iron upgrades to the amps?? Also how do they work ( or do they at all ) with the new soft start kit??

[Paul Joppa]

The MQ upgrades will work equally well with either driver.

If you know you will stay with the 2A3, then I would get the Paramour II iron with the BH-6 plate choke, which has more inductance than the BH-7 but can't handle the 300B plate current. The parafeed capacitor would be larger, 10uF for the Paramour choke and (if I recall correctly) 5.6uF or 6.8uF for the Paramount choke. Both packages have the same output transformer (BH-5).

I think Doc B has posted on the sonic impressions of the MQ iron, but I can't find the post right now. Hopefully someone has bookmarked it!?

[shelby1420]

Hey all, I notice that I only get the pop with one of my amps, have not swapped tubes yet, just found that a wee bit odd, does this make sense??