I carried out a rectifier shootout on my CSP2+.
All the following rectifier tubes were burned in for >24 hrs each
1. RCA – JAN 5R4GY 2x "D" Getter Black Plates (1950s or earlier ??)
2. Philips 5R4GYS Grey Plates Round Dimple Getter (1970s)
3. Brimar 5R4GY 2x "D" Getter Black Plates (1950s)
and compared against my default rectifier
4. Tung Sol 5Y3GT Black Plates "D" Getter (1950s).
My CSP2+ uses the following default tubes
2x Siemens E188CC Grey Shields for the L/R position
1x Amperex *USA Pinched Waist "D" Getter for the input position.
My Audio Chain is as follows :-
Oppo BDP 95 > Soundsilver Symmetry RCA Cables > CSP2+ > Beyerdynamic DT880 600 Ohms
This audio shootout is based on headphone usage so YMMV if you are using your CSP2+ as a preamp.
1. RCA - JAN 5R4GY 2x "D" Getter Black Plates (1950s or earlier ??)This contributes to the largest soundstage of all the rectifiers.
The spatial height dimension is most pronounced here.
Mids are neutral, so if you like a neutral sound and use your CSP2 as a preamp, this might be your ticket.
Bass is not boomy but is impactful and tight.
Drums have elastic quality.
Instrument separation is excellent (the best of this lot) and very distinct.
Nice Airy sound to Cello strings.
2. Philips 5R4GYS Grey Plates Round Dimple Getter (1970s)This is
the rectifier tube according to Kevin Deal of Upscale audio.
Compared with the neutral RCA tube above, the mids now have a very wonderful dose of tube warmth added to them.
The mids are so organic that many users are likely to get audio orgasms from using this rectifier.
This is one of those tubes for female vocals which help convey emotion and draw the listener into the music.
I can thus understand why so many positive reviews have been posted on Kevin Deal's website.
Instrumental strings have a very nice airy reverberation.
Instrument separation is good but not as distinct as the above-mentioned RCA rectifier. This is just a minor quibble.
Bass is impactful, tight and not too boomy.
3. Brimar 5R4GY 2x "D" Getter Black Plates (1950s) Made in UKShort history lesson here.
There are 2 Great ones in the tube rectifier world.
(a) WE 274B
(b) GEC/Marconi U52
The Brimar 5R4GY has earned (not just from me) itself a rather legendary reputation where tube rectifiers are concerned.
Yes, this is one of
those tubes which can be mentioned in the same breath as the above 2.
(and YES, in case you are wondering, the Mullard GZ34s are over-rated and over priced....but that is another story

Ok. History lesson over.
Back to this tube.
If you thought the mids of the Philips 5R4GYS were really organic and wonderful in a tube warmth kind of way, then the mids from the Brimar tube are really to die for.
This is where the Brimar rectifier earns its reputation for being WE 274b "like".
Bass sounds from this tube is the most "3D" like with Depth, Width and Height. Drums are not just a simple "thumph" but have tone as well!
The tonality (especially string instruments) from this tube is the most realistic sounding.
Instrument separation is good but not as distinct as the above-mentioned RCA rectifier. This is just a minor quibble.
Bass is impactful, tight and not too boomy.
4. Tung Sol 5Y3GT Black Plates "D" Getter (1950s)The CSP2+ was designed to use 5Y3 rectifiers.
No surprises that in my system, the already highly rated Tung Sol sounds just as good as the Brimar rectifier in almost every department.
The Tung Sol rectifier does lose out to the RCA rectifier in terms of soundstage though, especially in the relative lack of height.
Ermm, what I'm trying to say is that before you rush out to grab that Brimar 5R4GY rectifier for your CSP2, you can get most of the sonics from using a humble Tung Sol 5Y3 instead.
However, the mids of the the Brimar are still the best organic sounding of all the rectifiers I tested.
Epilogue a.k.a Rectifier Shootout #2I have another SE EL34 based tube amp for my speaker setup which is designed around the 5U4 rectifier.
After the rectifier shoot-out in the CSP2+, I carried out a similar one for my speaker amp.
For that other shootout, the Brimar rectifier totally obliterated the competition.
Every other member in my family literally asked me what I did to my audio system to make it sound so organic and rich and inject a hypnotic presence to the sound.
The mids from the Philips 5R4GY still sounded warm and organic.
This is consistent with the tons of accolades from Kevin Deal's customers who have used the Philips 5R4 on external speaker amps.
However, the Brimar takes the mids to a whole different higher level, into the Stratosphere of the legendary WE 274B and GEC U52 but without the cost!
So if you have a speaker amp which uses the 5U4, the Brimar 5R4GY is highly recommended. The next best thing would probably be a Philips 5R4GY from Kevin Deal.