Rectifiers are the unheralded heroes of the vacuum tube world, and like Rodney Dangerfield, they get no respect - but they should.
In a vacuum tube circuit, the power supply provides the necessary AC voltage from the mains. The rectifier then has the important role of converting that AC voltage into DC for the operation of the other vacuum tubes in the circuit.
So as their source of DC, the rectifier has an important influence on the performance of the other vacuum tubes in a circuit, and thus plays a major role in the overall sound quality of the circuit. Rectifiers are important - respect!
Care package from Yazaki-san!
Friend Yazaki-san sent me a care package from Tokyo with 3 vintage rectifiers in ST bottles (an STC 5R4GY KB-FE, and 2 x RCA JAN CRC-5R4-GY), along with a very tasteful choice of green tea.
Thank you, Yazaki-san, for your thoughtfulness and generosity!
Monaural PX25A (DA30) SET amplifiers built by Yazaki-san for Ookubo-san.
Ookubo-san, a friend of Yazaki-san's, passed away. Yazaki-san had built a nice pair of monaural PX25A (DA30) SET amplifiers for Ookubo-san about 13 years ago.
Close-up of one of the monaural PX25A (DA30) SET amplifiers.
The amplifiers were quite an effort to build, and it took Yazaki-san almost a year to complete them. Upon Ookubo-san's passing, the amplifiers needed to go to a good home, and Yazaki-san's good friend, Alan-san, provided them with that new home.
Ookubo-san's wife, Setsuko-san,
That's Ookubo-san's wife, Setsuko-san in the photo above, with the photos of the monaural PX25A (DA30) SET amplifiers at their new home with Alan-san.
Yazaki-san: "Also, at the request of Ookubo-san's wife, I patiently worked on selling his collection of rare tubes, which are now extremely valuable, and thankfully most of them were purchased by friends. Of course, it would be a great blessing for Ookubo-san in Heaven, his wife, and I, that the belongings of Ookubo-san were passed on to my friends, each of whom is a true music fan. And also for me, I also thoroughly enjoyed the sounds of the various rare vintage tubes in the Ookubo collection."
Vintage STC 5R4GY KB-FE Rectifier.
"Dear Jeff-san, This is just a small part of the "Ookubo collection". Ookubo-san was a big fan of classical music, and owned quite a few STC 5R4GY (4274B) tubes, which he seems to have loved dearly. I also love STC tubes. I really enjoyed my "Tube Adventure" with the "Ookubo Collection". I hope you enjoy it too, Jeff-san!"
"The STC 5R4GY is the exact same tube, also marked as STC 4274B. Like the GEC U52, it is a wonderful sounding rectifier tube with the merits of British tubes, and is one of about seven that Ookubo-san owned. The RCA 5R4GY has the bright, clear sound quality that is unique to vintage RCA tubes."
Vintage RCA JAN CRC-5R4-GY rectifier.
Here's a link to the specifications for the RCA 5R4GY over at Frank's Electron Tube Data Sheets: HERE
The Triode Lab 45 EVO SET integrated amplifier can use a number of different rectifiers in its circuit: "Recommended Rectifier Tubes : 274B / GZ32 / 5V4 / 5T4 for best sound. It can also use 5U4 / 5Y3 / 5R4," says Triode Lab.
The rectifier versatility of the 45 EVO makes it ideal for trying Ookubo-san's RCA JAN CRC-5R4-GY and STC 5R4GY (4274B) rectifiers.
The overall tube complement varies over time in my 45 EVO, as I enjoy doing a little tube rolling from time to time, but for this listening session the inputs were NOS Amperex Bugle Boy 12AU7As, the drivers were Psvane CV181-T IIs, and the power tubes were Emission Labs mesh-plate 45s.
I've been listening to some very fine current production 274B rectifiers in the Triode Lab 45 EVO SET integrated amplifier, like the Sophia Electric Aqua 274B, the Sophia Electric Aqua II 274B, and the Psvane Acme Series 274B.
Left to right: Aqua 274B, Aqua II 274B, Psvane Acme 274B, RCA JAN CRC-5R4-GY, and STC 5R4GY (4274B).
I love the performance of 274B rectifiers, they really have been my favorites to date, so I was very interested to hear how these vintage RCA JAN CRC-5R4-GY and STC 5R4GY rectifiers would compare.
I noticed that in Yazaki-san's description he referred to the STC 5R4GY as being the same rectifier as a 4274B, and it got me to wondering how similar the 5R4GY / 4274B were to the "regular" 274B.
AI to the rescue: "The 5R4GY rectifier is known for its ruggedness and can handle higher voltages, while the 274B rectifier, although having similar electrical characteristics, is often more expensive and is considered to provide a different sound quality in audio applications. Both types have their unique advantages depending on the specific requirements of the audio system."
Thorens TD-124 turntable with Ortofon SPU GTX S cartridge, Triode Lab 45 EVO SET amplifier.
I like to think that Ookubo-san in Heaven is enjoying listening along with me as I listen to his vintage STC 5R4GY and RCA JAN CRC-5R4-GY rectifiers in the delicious little Triode Lab 45 EVO SET integrated amplifier.
I call this my "vintage inspired" audio system because of my vintage Thorens TD-124 turntable (restored by Artisan Fidelity), and the rather amazing vintage Stokowski Altecs with their Duelund CAST tinned-copper crossovers.
To be fair, the Triode Lab 45 EVO is a contemporary amplifier, but an amazing performer. It's a match made in heaven for the Altecs. There's very few amplifiers at any price that I've come across that can perform at the 45 EVO's level.
Ortofon's new SPU GTX S moving-coil phonograph cartridge.
The Leben RS-30EQ vacuum tube phono preamplifier is also a contemporary component (and has a real synergy with the 45 EVO), as is the Ortofon SPU GTX S (above) that is in for review.
Hint: The Ortofon SPU GTX S moving-coil phonograph cartridge with its miniature step-up transformer incorporated into the SPU body shell is a fantastic performer in this audio system. I love it.
Those in the "audio underground" know that the combination of an idler-wheel turntable, an SPU cartridge, a single-ended-triode (SET) amplifier, and vintage Altec loudspeakers are one of those "magic" audio combinations that always delivers the music with a "full of drama" flesh & blood presentation.
Just a note about these listening impressions: these listening impressions are a "rectifier tasting" session - think "wine tasting" session - to get a quick overall feel for each of these rectifiers' performance in this system.
The rectifier I like the best in this audio system might not be the one you like the best in your audio system, but I would encourage you to try them all - and others as well - for a little audio fun & games of your own.
Also, I'm only listening to one album for this "rectifier tasting" - Gillian Welch & David Rawlings' Woodland Studios - to keep things simple, as this is a "just for fun" spur of the moment listening session. I'll do more comprehensive listening with a wider variety of music later.
Interesting AI tidbit: "Woodland Studios is a historic music recording studio in East Nashville, Tennessee, owned by Gillian Welch and David Rawlings. It was originally built as a movie theater and became a studio in the late 1960s. The studio has hosted recordings by numerous artists, including Nitty Gritty Dirt Band, Jimmy Buffett, and George Strait."
Gillian Welch's and David Rawlings' Woodland Studios album.
Ok, let's do a little listening.
RCA JAN CRC-5R4-GY rectifier.
First up, I thought I'd listen to the vintage RCA JAN CRC-5R4-GY rectifier in the 45 EVO. This is the later version with a single bottom getter, versus the earlier version with double D bottom getters.
I've been enthusing over how emotionally engaging this audio system is. I feel it as much as hear it, which is as it should be when listening to music in a fine audio system.
Woodland Studios isn't your usual duo album of Gillian Welch & David Rawlings, it includes a lot of other musicians as well, which you can read about HERE.
With the RCA JAN CRC-5R4-GY rectifier in the 45 EVO the overall system tonality was gorgeous, and possessed a certain liveliness of being that I found very enchanting.
What I heard from the RCA was a clean & resolving presentation of the music, with lots of nuance, vivid imaging, a big sense of recorded ambience, and a very colorful & natural sounding tonality. Very balanced from the top to bottom of the audio spectrum.
What I felt from Woodland Studios with the RCA in the 45 EVO was goosebumps all over my body and shivers of delight. The RCA gets the music right. It gets the emotional intent of the songs right. It makes the music sound and feel real. This music has a darkly beautiful tranquility to it that the RCA makes very apparent.
Vintage STC 5R4GY.
Next up was the vintage STC 5R4GY rectifier.
Listening to Woodland Studios with the STC in the 45 EVO was noticeably different than with the RCA. Overall, the STC gave the music a bit of a mechanical quality compared to the liquid & natural sounding RCA. The STC was less resolving, and revealed less nuance in the music. Overall system tonality was ok, but was not ravishingly beautiful like the RCA.
What I heard: The dynamics were more pronounced than the RCA, the bass region was not quite as "fat" sounding, there was perhaps a touch more clarity in the low midrange, with the midrange being a little more forward. The presence region seemed a little more prominent, but the STC lacked the sense of sparkle and ambience of the RCA in the brilliance region of the recording.
What I felt: With the STC I didn't connect with the music like I experienced with the RCA, and I didn't get a sense that the emotional vibe of the music was being communicated to me very well. I'm not quite sure how to say it, but the STC felt a little "mechanical" in the way it presented the music.
I know that Ookubo-san and Yazaki-san are very fond of the STC 5R4GY rectifier, but for whatever the reason, it wasn't a happy match in this equipment context. It wasn't bad, but it just didn't make listening to Woodland Studios very edifying.
Psvane Acme 274B.
The Psvane Acme 274B was up next.
Woodland Studios with the Psvane Acme 274B in the 45 EVO provided a rich, warm, organic, and refined overall tonal balance. It was the audio equivalent of a fluffy warm sweatshirt that wrapped around me and made me feel comfortable.
What I heard: The Psvane has a liquid and natural flowing quality to it that I found appealing. It's not as clean, resolving, and nuanced sounding as the RCA, but overall it was well balanced top to bottom in the audio spectrum. The Psvane seemed a little more recessed in the presence & brilliance regions than the RCA, with less sparkle and sense of ambience.
What I felt: The Psvane had a comfortable and relaxing feel to it, and was more laid back feeling than the RCA, but the Psvane couldn't match the RCA's ability to induce goosebumps and shivers of emotion, which the RCA accomplished so easily. The differentiation of the emotional vibe for the individual songs was less pronounced with the Psvane than with the RCA, and the overall emotional impact was less than the RCA.
Sophia Electric Aqua 274B.
Next up was the Sophia Electric Aqua 274B, and this is the rectifier that ignited my original passion for 274B rectifiers.
Woodland Studios with the Sophia Electric Aqua 274B was lively, dramatic, and emotionally evocative.
What I heard: Beautiful overall tonality, organic & naturally warm sounding, with a beautiful liquid flow to the way the music unfolds. The Aqua also had lots of clarity and resolution, but not as much as the RCA, but more than Psvane and the STC. The Aqua also provided a very spacious overall presentation that filled the room, and with images that had lots of body and presence.
What I felt: The Aqua conveyed feelings of beautiful tranquility, intimacy and refinement, with vivid & expressive tone colors. The Aqua wasn't as expressive in the goosebumps & shivers of delight department as the RCA, but clearly bettered the Psvane in that regard.
I really like the original Sophia Electric Aqua 274B. It does everything right. It sounds great, and it feels great. Only the RCA betters it in the "feels great" category. With the Aqua 274B, when the music is playing, I just want the music to keep playing, caressing me with its musical charms. It is a really good 274B rectifier.
Sophia Electric Aqua II 274B rectifier.
The final contender is the Sophia Electric Aqua II 274B rectifier.
Woodland Studios with the Sophia Electric Aqua II 274B in the 45 EVO was full of emotional drama, was a bit dark and rich, but still resolving and nuanced, and with a big spacious & tonally beautiful presentation of the music. The emotionally dark, beautiful, and melancholy feel of Woodland Studios was front and center with the Aqua II.
What I heard: The Aqua II was both a bit dark and rich sounding, but also resolved a lot of information, traits that don't usually go together. The Aqua II was the very evenly balanced from top to bottom in the audio spectrum. Tonally it sounds the most romantically "beautiful" of all these rectifiers. It's a bit uncanny in the presence and brilliance regions that it has lots of definition, and a huge billowy room filling sense of space, while also being a bit dark and rich. Images are vivid and have a lot of body and flesh & blood presence.
What I felt: The Aqua II has this dark, beautiful, ethereal quality to its presentation that is very enchanting and emotionally involving. The music flows out as a liquid stream of gold, full of meaning and life, with a presentation that emphasizes the emotional message & impact of any given song.
Vintage RCA JAN CRC-5R4-GY.
On Woodlands Studio the vintage RCA JAN CRC-5R4-GY was the most timbrally "real" sounding and feeling of these rectifiers. It also injected a touch of magic into my mind & emotions - a certain illumination of feelings & lightness of being - while listening, that these other fine rectifiers couldn't quite match.
There's something so "right" about the vintage RCA rectifier in musical terms that it's a little hard to articulate, but I could feel it creating musical magic in the deepest recesses of my soul, with a full compliment of goosebumps and shivers of delight served up.
Left to right: Aqua II 274B, Aqua 274B, RCA JAN CRC-5R4-GY, Psvane Acme 274B, and the STC 5R4GY.
My three favorite rectifiers in the 45 EVO were the RCA JAN CRC-5R4-GY, the Aqua II 274B, and the Aqua 274B.
The Psvane Acme 274B was also very good, but its performance didn't quite make it to the podium with the other three.
I was puzzled by the performance of the STC 5R4GY, particularly given Ookubo-san's & Yazaki-san's fondness for it, as it just wasn't delivering any magic with this complement of audio kit. Perhaps I need to listen to some opera or other classical music with it to see if I can discern more about its performance in that context.
I would like to thank Ookubo-san, Setsuko-san, and Yazaki-san for their generosity and thoughtfulness in sharing the RCA JAN CRC-5R4-GY and STC 5R4GY rectifiers from Ookubo-san's vacuum tube collection with me. Thank you so much, it was a true adventure!
I plan to listen to these rectifiers with much more music over time, so I may report back on any new revelations I have about their performance.
As always, thanks for stopping by, and may the tone be with you!
Late additions!
Thanks to all of you who have been telling me about your favorite rectifiers after I wrote this article, I am certainly intrigued by your reports, and appreciate your recommendations. 🙂
It occurred to me that I had stashed away a pair of Haltron 5U4G rectifiers that I had tried in my McIntosh MC30 monaural amps. If I remember correctly, Yazaki-san sent these to me as well, way back when we were modding the MC30s. I seem to remember they didn't sound as good in the MC30s as the Sophia Electric Aqua 274B rectifiers did, so they went into my vacuum tube library for a later time.
Haltron 5U4G rectifier from London, England.
Well, that later time is now, as the Triode Lab 45 EVO SET integrated amplifier can also utilize 5U4G rectifiers, so I thought I'd give the Haltron 5U4G rectifier a listen while my listening impressions to the other rectifiers were still fresh.
Vintage Thorens TD-124 with the new Ortofon SPU GTX S moving-coil cartridge with built-in SUT.
I put Woodlands Studio back on the Thorens - loving that new Ortofon SPU GTX S! - and did some listening.
Haltron 5U4G rectifier from London, England.
The Haltron 5U4G rectifier from London, England, displayed that "British Fineness of Tone" that Yazaki-san refers to, and it really sounds good in the 45 EVO.
Rectifiers can really sound different in different amplifiers and equipment contexts, and while the Haltron didn't impress me in the MC30s, it is impressing me right now in the 45 EVO.
What I heard: In the 45 EVO the Haltron gives a relaxed, relatively polite & laid-back, and neutral sounding presentation across the audio spectrum. The Haltron has excellent clarity and resolution, and uncovers lots of nuance, although it is not quite up to the RCA in that regard. Nice overall tone with a nice sense of "truth of timbre" in the instruments. Imaging is good, and sounds relatively natural in terms of vibrancy & presence, but is a little relaxed and laid-back sounding.
What I felt: There's good tone color distinction (i.e. the additional tones added to triads), which helps to convey the emotions that Gillian & David are trying to convey in their chordal voicings. Overall, the Haltron gave me a relaxed, laid-back, sense of peace while listening to Woodlands Studio. I was also struck by feelings of beauty from the music, and the artfulness of David's guitar playing. Polite and intimate feelings was my reaction to the Haltron, and I found it easy to relax into the music.
So where does the Haltron rank in comparison to the other rectifiers here? Overall it gets pretty close to the Sophia Electric Aqua 274B, but is a little drier & brighter sounding in its overall presentation. I guess in overall ranking I would say it betters the Psvane Acme 274B by just a little bit, but falls a little bit below Aqua 274B. The Haltron 5U4G is a really nice sounding rectifier in the 45 EVO.
Left to right: RCA 5R4GY x 2, Aqua II 274B, Aqua 274B, Haltron 5U4G, Psvane 274B, STC 5R4GY, and the RCA 5U4GB black plate.
Will wonders never cease? As I was rummaging through my tube stash this morning I also came across a quad of RCA 5U4GB black plate rectifiers. These date back to my MC30 mono amps adventures, but they were displaced by the very fine sounding Sophia Electric Aqua 274B rectifiers in that application. These have the stubby little bottles, and aren't nearly as sexy to look at as ST or globe bottles.
Vintage RCA 5U4GB black plate rectifier.
The vintage RCA 5U4GB black plate rectifier sounds great with Woodlands Studio playing on the Thorens. Overall, it has really nice natural tone, which kind of reminds me of the suave Aqua II 274B, but maybe just a little cleaner sounding.
What I heard: There's lots of flesh & blood image presence with the RCA 5U4GB black plate. Big & bold images, rich & warm, smooth & liquid, and a sense of room filling ambience from the recording. It throws a wide and room filling soundstage with a lot of depth that really impressed me. It's darker and richer than the RCA 5R4GY with its ST bottle, but lacks that rectifier's resolution and exciting presentation. It sounds relatively laid-back, but is well balanced across the audio spectrum. The RCA 5U4GB black plate is not a very sexy looking rectifier with its stubby little bottle, but it's very sexy sounding, and very tonally natural. I really like this RCA 5U4GB black plate in the 45 EVO!
What I felt: I think it's important to distinguish what something - in the case the RCA 5U4GB black plate rectifier - "feels like" from what it "sounds like", because "sounds like" doesn't always capture the full character of a component and its ability to deliver the emotional content of music. The music sounds beautiful through the RCA 5U4GB black plate rectifier. Emotionally evocative, and dare I say it, it has a human touch to it, in the sense of real, live, humans making music. It has a burnished, liquid, polished, and emotionally stimulating beauty to its presentation.
While RCA 5U4GB black plate doesn't sound exactly the same as the Aqua II 274B or Aqua 274B in the 45 EVO, it is right up there with them performance-wise. The RCA 5U4GB black plate is really nice sounding rectifier in the 45 EVO, and I'm feeling rather thrilled that I discovered a quad of them in my vacuum tube stash.
Left to right: RCA 5R4GY x 2, Aqua II 274B, Aqua 274B, Haltron 5U4G, Psvane 274B, STC 5R4GY, and the RCA 5U4GB black plate.
I encourage you to try a few different rectifiers in your amps, which one will work best for you will depend upon your audio kit and personal tastes, but its a lot of fun to do some tube rolling.
Ok, that's all for now, as I have to shake myself out of my musical reverie and go mow the lawn. Sigh. I tell myself it's a good cardio workout in order to feel better about it. 😉
Thanks for stopping back by, and may the tone be with you!
