Interested in Members' Experiences with Rectifier Tube Rolling in Modwright PS 9.0 and 9.9

I switched several years back from a 5AR4 to the Phillips 5R4GYS in the PS 9.0 power supply feeding my Modwright-Sony 5400es. I prefer the midrange of the 5R4GYS over all of the 5AR4's I've tried including the metal base one. I find the 5AR4 tube to be a little lean in that application. This past week I tried both the Mullard GZ32 5V4, and a 1949 RCA 5U4G black plate in the PS 9.0 power supply. In a direct comparison, both were clearer and had better instrumental separation than the Phillips 5R4GYS in my system. The 5R4GYS was slightly superior in bass heft. On balance the Mullard GZ32 is what I've chosen to keep in my PS 9.0, at least until I'm able to try the Tung Sol 5U4G top getter black plate.
You need to try a RCA 5R4GY with light brown base.  That is my clear favorite of all rectifier tubes I have tried in my preamps.  They are readily available on EBay for $20 or so and they last a long time.  Don't be concerned about the maximum rating of 4uf for the filter capacitor on the rectifier.  This is only for high voltage, high current conditions.  I use mine into a 100uf capacitor with no problems.
The original Sovtek 5AR4 failed catastrophically and took out a couple resistors requiring me to send my 9.0 back to Modwright so Dan could fix it.

According to Dan, my event was unique provoking him to alter the 9.0 circuit so if I ever suffered another catastrophic rectifier failure, no other components of the circuit would be destroyed.  I appreciate the fact that Dan took the time to rethink the circuit.  

Dan put in a new Sovtek 5AR4 and everything was working and sounding fine.  BUT...I have been using Gold Lion tubes sourced from Cryoset for many years now and have found them to have a very neutral sound and last a very long time.  Fortunately Gold Lion makes a GZ34 that is a suitable rectifier replacement so I ordered one from Cryoset.

After giving the GZ34 time to warm in to the circuit, the sound began to take on a sightly warmer character, meaning a bit more going on in the lower midrange/mid-bass. I should also mention that I ordered a HAL-O III-30 Stabilizer from Herbie's Audio Lab for the new tube.  This titanium tube damper is specifically intended for tubes that run very hot.  It fits very tightly on the GZ34.  With the HAL-O, the soundstage opened up increasing height, depth and width when appropriate to the music.  

cellcbern - Glad you brought this topic up.  Hopefully other Modwright users will chime in with their experiences.
I've tried the RCA 5R4GY with the light brown base.  It was not in the same league in the Modwright PS 9.0 power supply as the Phillips 5R4GYS, RCA 5U4G black plate, and Mullard GZ32 5V4. 

I will post the results once I've tried the Tung Sol.

I have been using a 1960's Mullard 5AR4 in my 9.0 PS which I like over the stock tube or the Create or Golden Lion.
Hi all,
Better late than never.  I've run all the above in my Modwright Oppo PS9.9 and recently have been using the GEC U52.  It is superb with great detail, great bass, layering, separation and a huge also adds some body and weight to the music that wasn't there with most others, similar to the Philips 5R4GY in that regard but more refined.  I was disappointed as well as a bit surprised that the "Holy Grail" Western Electric 422A seemed a bit bright and harsh.  Anybody else here find that?  Could be that it had tested new so not run in as yet.  I plan on running it for 100 hours starting this weekend and will see what transpires, but for now the U52 is going to be tough to top!

Thank you to everyone’s contributions here.
I just ordered a GEC U52 today for my Modwright 205/PS 9.0 V10

There’s an epic rectifier thread @ Head-Fi and when some comments here echoed those I saw on the other thread and articles, I pulled the trigger.