Capacitor upgrade for prima Luna dialogue premium HP

If you can do it, replace the electrolytic power supply capacitors with polyproline for better ESR, more margin for higher voltage rating, and because electrolytic capacitors have a limited shelf life, polypropylene do not have to be replaced every few years. 

Hi Richard,

I recently upgrading some of the caps in my Prima Luna Dialogue 4 amp. If you're interested, you can find the thread here.

I upgraded the capacitors on the input stage with Dueland CAST-PIO Hybrid copper/silver foil caps. I also upgraded the capacitors on the autobias board with V-CAP ODAM caps (see attached pic).

While I was at it, I changed some of the tubes to NOS. For the 12AX7s, I added NOS Amperex with green labels made for Hammond Organ, purchased from Brent Jesse. For the 12AU7s, I added NOS Brimar from Upscale Audio.

I added some tweaks too: Herbie's HAL-O III tube dampers, Isoacoustics OREA isolators, a Synergistic Research Blue Quantum fuse on the autobias board, an Isoclean Hifi gold fuse for the main fuse, and a DH Labs Power Plus power cord.

Altogether, it breathed new life into a 12-year-old amp.

Since you were asking about caps specifically, after my cap upgrade I noticed improvements that included slightly better resolution, somewhat better tonality, and overall a more organic and relaxed presentation.

Bryon

@whyrichard , The Jupiter copper foil are really close sonically to the Jensen copper foil. Have used both. The Non-HP version of your amp has a lot more room to fit almost any size cap. The Jupiters will fit in the HP version but will require some careful placement. The stock PL coupling caps are inexpensive metalized film. 

For the HP version you will need 8 Jupiter coupling caps, and be sure to add two 0.1uf Jupiters to replace those metalized 0.1uf on the voltage rail for the input caps. These will make just as big or bigger difference than the coupling caps. 

For coupling caps, I like some vintage caps like Hovland and Chocolate Drops (mylar/polyester film caps from Sprague or its licensees).  

I still have Hovland caps in my PL for 18 years and they still sound sublime with RFT Siemens EL34s, and a mix of 12ax7 to roll for gains: Mullard box plate, Amperex Heerlen, Telefunken, and Tungsram.