This week I made some much needed updates to my Paramount-ish amps. There is a thread on their build somewhere on the archives.
These amps were originally designed to add a much larger footprint for experimentation. They were built before the Kaiju was released which addressed the minimal shortcomings of the original Paramounts. The operating point is different, 350v P-K, -76v, 50mA, 5k. To lower the voltage of the power transformer two PC-2 plate chokes were used in the power supply. The parafeed choke is from Magnequest gapped for 50mA and the output transformers started with MQ EXO-050’s with full nickel. A couple of years later I added TL-404 XL’s with a couple of switches to go between these two OPT’s. To play around with drivers, I split the shunt regulator tube to an additional 9 pin and an 8 pin socket. This allowed me to use a 5670 for the shunt reg side and play around with tubes for the driver. I tried 6J5 and variants and 7A4 locktels with a tube converter. It was a lot of fun exploring what was out there.
Fast forward another three or so years and my system has had a few changes. The Altec 19’s were replaced by Altec 755A’s in WE cabs and Rythmik subs. I use the HPF in the subs to feed 80Hz and above to the Altecs. With no crossover, these little drivers show any changes you make. After the speaker swap, the 050’s in nickel were just too much for me. It’s hard to describe but in the end, I couldn’t listen to them for long lengths of time and spent most of the time listening to the 404’s.
I made a fortunate trade and ended up with a pair of pinstripe EXO-050’s. These were swapped with the full nickel and from the first record played I was happy. Compared against the 404’s, the pinstripe’s were significantly better in this amp. PB attributed it to increased magnetic headroom. Whatever it was, the improvement was what I was looking for. The 404’s were removed along with the switches and these amps are finally where I want them. For drivers, after all of that tube rolling, I couldn’t find one that beats the GE 5670 in my system.
I included a few before and after photos. I’ve seen a few people struggle with large caps in their build. I added a photo of my work around. Just put a standoff in with a cable holder and zip tie the cap to the cable holder.
