Review: Valve Amplification Company Phi 300 Tube amp

Category: Amplifiers

With no small amount of anxiety, I recently replaced my VAC Renaissance Signature 70/70 amp with VAC’s newest amp, the Phi 300. The Ren Sig 70/70 is a sonically and visually gorgeous amp, with detail, power, control and the most 3-dimensional soundstage projection that I had ever heard from any amp. Why fix what isn’t broken?

The Phi 300 now has about 90 hours of playing time on it in my home. The manual states that it was played for 48 hours before it left the VAC factory, so figure that it has close to 140 hours total time, and maybe that should be adjusted downward to account for the effects of shipment. In any event, I think it has largely settled in to its basic performance level, although there may be marginal improvements over another 100 hours or so of play. This amp can be run in either triode or ultralinear mode, with single-ended or balanced interconnects. I have tried all combinations and have found, at least in my system, that it sounds best driven with single-ended interconnects and operated in the triode mode. I have used only the stock VAC tubes.

Before evaluating the Phi 300, let me set forth the associated equipment. The preamplifier is the VAC Renaissance Signature Mk II with the inboard phono stage (power cord: Stealth Cloude 9). The digital front-end is the Zanden 2000 Premium Transport and the Zanden 5000 Signature DAC (power cords: Michael Wolff Carbon Ribbon Source). These units (exclusive of the power supplies to the transport and DAC) are placed on a Sistrum SP-5 rack. The analog front-end is a Kuzma Stabi Reference turntable, with a Triplanar VII tonearm and a ZYX UNIverse X-SB cartridge. The turntable is on a Neuance platform that in turn sits atop a homemade turntable stand made of Ipe wood (with a high rigidity-to-mass ratio). The Phi 300 is on a Sistrum SP-101 stand and connected via an Elrod EPS-3 Signature power cord directly to the outlet (Furutech FP-20A(R)). Speakers are the Verity Audio Lohengrins. Power is supplied through an old Topaz 10kVA EI-style transformer, a 350 lb beast that is hard-wired in the basement to produce a balanced 60-0-60 output with a technical ground that is then routed through a Tice Power Block IIIB Signature for all components other than the amplifier. Interconnects are Stealth Indra and M-21, and speaker cable is Stealth Ultimate Ribbon in a custom bi-wire configuration. The room is approximately 21’ wide by 29.5’ long.

The first thing I noticed after hooking up the Phi 300 was that it was fast, very fast. Perhaps the only drawback of the Ren Sig 70/70 of which I was aware before getting the Phi 300 was that it was not as fast on transients as other amps I had heard. I think this is largely due to the 300B tube, as it tends, at least in my experience, to produce a richer sound at the expense of some speed. My old VAC PA 100/100 (another classic VAC amp) with KT-88s, for example, was marginally faster than the Ren Sig 70/70, but was far behind it in every other category. The speed of the Phi 300 has not really increased over the break-in period. It remains the fastest amp I have ever heard. Period.

The second thing I noticed at the beginning of the break-in process is that the Phi 300 produced a deep, but well controlled bass. I always thought the bass on the Ren Sig 70/70 was superb (and it is), but it was inferior in comparison to the bass from the Phi 300 right out of the box. After about 60 to 70 hours of playing time, however, the bass from the Phi 300 improved dramatically. It is enormously deep; it has a texture to it that enables you to experience it in a way that I can only describe as being more physical than sonic; and most incredibly, it has serious “slam” and it is extraordinarily well controlled. It produces the best bass I have ever heard, even from some of the most expensive solid-state amps that, generally speaking, are better at bass reproduction than tube amps. The Phi 300 trounces them in this department.

The third thing I noticed at the outset was that the 3-dimensional soundstaging and imaging just weren’t there. The soundstage was compressed, and the imaging was sloppy. My anxiety over selling the Ren Sig 70/70 was a little elevated at this point, to say the least. At around 60 to 70 hours of playing time, however, this changed. In a big way. The soundstage is wide (extending well beyond my speakers) and high and deep (extending behind the rear wall). Imaging is precise. Instruments and voices are clearly discerned at precise points across this expansive soundstage. The most amazing part, though, is that there is an extraordinary amount of detail without any sacrifice of that legendary VAC holographic, airy sound. How VAC managed to get this amount of detail while exceeding the richness and lusciousness of their 300B based amps is a complete mystery to me.

So, the bottom line is that this amp has lightning speed, incredible bass with slam and control, exquisite detail across the entire audible spectrum, the ability to handle with ease dynamic contrasts from ppp to fff; and it projects an expansive soundstage with amazing imaging and an airiness and delicacy that I can only describe as magical. Or perhaps stunning. Or perhaps jaw-dropping. Let me try to share a few recordings with you. I always find this the most difficult thing to describe, but I’ll try.

Sonny Rollins’ “I’m an Old Cowhand” on Way Out West (XRCD24, JVC) is clean, crisp and balanced. The timbre of the tenor sax is completely natural; you can experience the reediness of the notes. The bass is deep, fast and punchy; and the cymbals and snare drum are reproduced with amazing clarity and crispness. “Prologue” on Dave Grusin’s West Side Story (CD, N2K-10021) is a great test of the sonic ability of any system or component. It sounded great with my Ren Sig 70/70. It sounds noticeably better with the Phi 300. The greater speed makes a huge difference in the transient attacks throughout this piece, whether drums, cymbals, trombones, muted trumpets or the tightly syncopated saxophone passages. “I Feel Pretty,” from the same CD, illustrates the ability of this amp to produce a layered soundstage, with speed, detail and the ability seamlessly to produce the most delicate of sounds against the most forceful. The airiness of the flute, coupled with the almost perfect timbre of each strike of a piano key and the low frequency extension on the piano and high frequency extension on the triangle, give rise to a truly “you-are-there” experience. One of my favorite CDs is Queen Latifah’s The Dana Owens Album (CD, A&M). Every single song on this album, which is wonderfully recorded, is a winner. (If you think Queen Latifah could perform only rap or hip-hop, you need to buy this CD immediately.) Her rendition of “Simply Beautiful,” performed as a duet with Al Green, shows what the Phi 300 can do with vocals. You can almost feel them in the room with you. This amp retrieves all of the small breaths, sighs and tremolos, and then places the two singers side by side in the rear of the soundstage – she slightly to the left of center and he slightly to the right of center – that make this seem as if it is personal performance for you.

Patricia Barber’s Companion (LP, Premonition Records 1999) is one of my favorite Jazz LPs, given both the content and the high quality of the recording. The bass on “Use Me” is luxuriously rich, not only because it is so deep and so well controlled, but also because the speed of the amp precisely reproduces each bass string pluck. Seriously deep bass with detail and speed. Wow! “Let It Rain” demonstrates both the speed and detail in the mid- and higher frequencies. Every fret movement on the guitar is picked up with so much detail that it is as if you are five feet away. The cymbals are detailed and delicate, with just the right amount of decay. Barber’s singing is rich and beautifully positioned in the middle rear of the soundstage (it was slightly more forward on the Ren Sig 70/70). “Black Magic Woman” is a magical, intoxicating experience, with the occasional applause from the audience layered across the soundstage in such a way as to make you feel that you are there with them, but with the best seat in the house.

The speed, retrieval of detail and decay of the Phi 300 are illustrated in “Polonaise de la Concert, Op.4,” on Itzhak Perlman (LP, EMI Japan EAA-85060). Each note from Perlman’s aggressive violin performance is fast, precise and detailed, while the accompanying piano notes (from Samuel Sanders) linger with a perfect tonal balance and decay. It sounds as if they are right there in front of you. Rimsky-Korsakoff’s Scheherazade, performed by the Chicago Symphony (Reiner), (LP, Classic Reissue of RCA LSC-2446), is a serious test of any system or component. It has extensive dynamics ranging from delicate ppp violin and harp solos to powerful fff full orchestral movements. The ability of this amp handle those dynamic extremes with total ease, to reproduce the reediness of the oboe and vibrations of the bows against the violin strings while projecting from the rear of the wide and deep soundstage an incredibly rich and deep bass with the fastest timpani you’ve ever heard (short of a live performance) is nothing short of extraordinary. This is one of my favorite classical performances. It was beautiful on the Ren Sig 70/70. It is magnificent on the Phi 300, which brings the reproduction to another level.

The “Trees They Do Grow High,” performed by Pentangle on Sweet Child (LP, Reprise 2RS 6334), is a beautiful ballad. The speed, detail, deep bass capability, and holographic soundstaging and imaging of this amp make the combination of Jacqui McShee’s silky voice, Danny Thompson’s double bass, Bert Jansch’s and John Renbourn’s acoustic guitars and Terry Cox’s drums and cymbals so vivid and real that it is just plain spooky. It is sheer pleasure listening to this on the Phi 300.

The bottom line is that the Phi 300 just does everything right. It presents the most detailed, natural, rich and holographic sonic image that I have ever heard. It is dead quiet, it handles the most delicate of notes to the most forceful of notes with total ease, and it seamlessly handles the deepest bass (which becomes more of a physical experience) to the highest frequencies. I cannot think of a single shortcoming, which puzzles me because I have always believed that all high-end audio components are imperfect as the designers must strike balances among competing factors. Having heard the Phi 300 after a sufficient amount of break-in, I think it is fair to say that it is the finest amplifier I have ever heard. In my view, the Phi 300 is not evolutionary; it’s revolutionary.

Associated gear
VAC Renaissance Signature Mk II preamp (with inboard phono stage)
Zanden 2000 Premium CD Transport
Zanden 5000 Signature DAC
Kuzma Stabi Reference Turntable
Triplanar Mk VII tonearm
ZYX UNIverse X-SB cartridge
Verity Audio Lohengrin speakers
Topaz 10 kVA EI-style Transformer
Tice Power Block IIB Signature power conditioner
Sistrum SP-5 rack
Sistrum SP-101 amp stand
Stealth Indra IC and Ultimate Ribbon speaker cables
Power cords: Michael Wolff Carbon Ribbon Source, Stealth Cloude 9, Elrod EPS-3 Signature
Congratulations on a fine review and an excellent system.
I'll bet it sounds incredible. I currently have a VAC Avatar Super driving Verity Parsifal Encore's and the sound is very good. I'm sure yours is on a whole new level though.

Enjoy the music Vac man,

Thanks so much VacMan, I've been waiting to hear your impressions. I've owned the 70/70mk3 and loved it. I now know what amp I'm saving up for... :)
Very nice review, Vac_man, and thanks for taking the time to post this review. I am glad to hear that this new Phi 300 amp has eased your anxieties from selling your beloved Ren. 70/70. I hope to upgrade my Musicblocs to the PHI series in the near future. Enjoy the music.
A superb review and serious system- I'm a little jealous- at least we share the same equipment rack :-) enjoy!
Thanks for such an insightful and thoughtful review. It is obvious you are now at a new level of enjoyment, which is tremendous.

Do you think you might next try the Phi 2.0 preamp? I have one and love it, though I'm not using the phono stage.

I'm also using Virtual Dynamics Revelation bi-wired speaker cables with pretty amazing results - they take a long time to fully break in (over 800 hours), but once they get there, the sound is incredible. Just something you might want to try, if you get the itch. I'm also using Elrod's Statement on my current amp, and power conditioner, with much better results than I got with the EPS-3 Signature. Quieter, faster, tighter, deeper bass and better overall dynamics. I'm offering these suggestions as a bit of a "give-back" to you for your excellent review, which we all greatly appreciate.

Thanks again and congratulations on owning what could be one of the best tube amps made.
You have penned an excellent, well thought-out, descriptive review that hopefully will bring many more buyers to the wonderful world of VAC equipment. My prayer for Kevin Hayes is audiophiles will purchase this amp solely based on your review. Great job VAC Man!
Nice review!

Do you know if the new 160 Musicblocs share some of the sound quality of the Phi 300?

Thanks for the well done review. I have a 70/70 mklll-s, so your comparisons are interesting. I look forward to hearing this new amp.

Does the new Phi 300 have a seperate chassis for the power supply like the 110/110?

It'll be interesting to see if Kevin will be coming out with a Phi 150 using the same circut but 4 less power tubes.
I own the phi Beta integrated and feel too with out a doubt it is the best amp/preamp / gear I have ever owned. I have owned several other tube brand gear but the VAC stands out and the phi gear is Kevin's best to date. Great review, enjoy!

In e-mails from Kevin and looking at the VAC website, I would think that the Standard 160 would share a sonic signature with the PHI 300 as the 160 circuit was derived from the technology on the PHI 300. Kevin did tell me that my Auricle Musicblocs' circuit was derived from the PHI 110. He also mentioned that the amp section of the most recent Avatar Super is almost identical to the Auricle Musicbloc, both containing new technology using the Triode Beam, KT88 tubes. You might e-mail Kevin to hear it straight from the horse's mouth, so to speak.
Vac Man indeed! Great review and a great system. I'd love to spin my favorite tunes on that rig- I get misty-eyed just thinking about it.

Enjoy your substantial- and worthwhile- investment my friend.
KW6- My conversations with Kevin lead me to believe that although the 160 Musicblocks share SOME of the characteristics with the Phi 300, the 300 is actually in a whole different league. This is due in large part to some additional mods Kevin made to the Phi 300 amps before they shipped. He apparently wouldn't ship them until he did a few more tweaks to get the piece "just right". Although I haven't yet heard one, I imagine I will before the year is out.

I agree with Sherod - Kevin will have the best answer to your question - the above is just from my recollection of conversations with him to figure out which would fit my needs the best.

I think it's obvious that the PHI line will be superior overall. That's why you have to pay more to get the best. For poor folks like myself, I'm temporarily happy with VAC's lesser lines that at least have some of the "trickle-down" technology derived from the new PHI line.
Thank you for the responses!
Very nice review.
Has anybody heard the new Musicbloc Standard 160? I know Kevin Hayes thinks they are really good. Any speculation as to whether they would they drive the heinously difficult Shahinian Obelisks?
Sam, I have the Phi 220 monoblocks with 220 watts a side and they handled my Wilson MAXX extremely well for a tube amp. Recently, I bought the Zu Definitions and considered selling the 220's as I don't need as much power now. Kevin told me the 160's would give me greater punch in the low end than even my 220's and still much of the sonic benefits of the Phi 220's with a little less resolution. Talk to Kevin, he is always straight with you and will give you his best idea on what to do.
Excellent, substantive review, Vac Man! I'd also be interested to read your observations regarding the Lohengrins. I've heard them at CES but in less than ideal conditions. Can you draw a comparison to either the Parsifal Encores - which I've owned and enjoyed for over five years - or the Sarastros?

All in all, a very impressive system.
Does anyone know if the Phi amps use circuit boards? The Renaissance amps are point-to-point wired.
Kevin is now up to the Phi 300.1 which I ordered several weeks ago, in part due to your glowing review. Since you haven't posted here for a while, I was wondering how your Phi is doing after 11 months - I'm hoping it sounds even better. I am also interested in talking to you about your Lohengrins - please send me an e-mail if you'd like.

Fplanner2000, I would be interested in your impression(s) of your new Phi 300. I would imagine that you'll fall in love with its performance. Perhaps you could start a new thread with your own review. I would look forward to that. Enjoy your new amp.

The Phi 300 is doing well after almost a year of use, mostly sporadic at least over the last 3 or 4 months as I have been very busy at work. Initially, I did not like the rounded design and preferred the more angular appearance of the Ren Sig series, but I have to say that the rounded design has really grown on me. The new 300.1 has the more angular look that I earlier liked, but now I'm not so sure I would prefer that over the look of the 300. I understand that the circuitry is the same -- maybe some layout changes -- and definitely a change in terms of the enclosure. I'd be eager to hear how the 300.1 compares to the 300 in terms of performance. And, of course, I'd be eager to hear how your 300.1 sounds after you have had a chance for it to settle in. It's hard for me to imagine how the performance of the 300 could be bettered -- it's that good.
After about 8 months with my 300.1, all I can say is WOW! It has done everything I have asked of it without breaking a sweat. It sounds neither tubey nor solid-state - it just sounds like the music. I am so pleased with this amp that I've set out to bring the rest of my system up to its level, to the extent my funds will allow. So....

Several months ago I acquired a pair of VSA VR-7se's by being at the right place at the right time and have been breaking them in along with re-cabling my whole system with Synergistic Research. This is obviously a work in progress, but the sound so far has been astounding, again anchored by the 300.1.

The 300.1 is lightening fast when the music calls for it, as well as incredibly dynamic, but not artificially so. The musicality, soundstaging and bass response are the best I've heard. The bass is tight, accurate, fast, full but not ponderously heavy - much better than my McCormack DNA-500, which surprised me. The mids are just breathtaking, as you might expect from VAC's top amp. The highs are extended, airy and very pleasing to the ear - there is no artificiality or edginess anywhere. The best compliment is probably that it just gets out of the way of the music. The VAC really allows you to hear into the music like no other amp I've ever heard - I concur with others who have said it just "does everything right". If you like VAC, you owe it to yourself to hear/audition this amp - it will probably rock your world, as it has done mine.

P.S. - There is apparently a tremendous synergy between VAC and VSA - I am the fortunate beneficiary of this and am loving every minute of it. The SR cabling also appears to be a great match with my system.

P.P.S. - I have found my system takes at least 15 minutes before the tubes get sufficiently charged where you'll want to start listening - come back 1 hour later and the sound improves dramatically. There is probably some interaction here between my VAC Phi preamp's tubes and the Class A tube output of my source as well, but I'm thinking the main reason is the warm-up for the 300.1. Believe me, it is WELL worth the wait!!
I have promised myself a VAC amp some time, but I use integrated amps. Can anyone comment on the Phi Beta 300 amps performance against the 300 with a VAC pre amp. I know VAC don't offer an integrated at the moment, but I would be looking 2nd hand. I wonder how near the integrated gets to the Pre/power. Thanks
You may be confused - the Phi Beta is a preamp, not an integrated amp. From talking to VAC, nothing else they currently produce or have produced in the past touches the Phi 300.1 amp.
Vac had an integrated called the Beta, but apparently they discontinued it:

I stand corrected - thanks. That was an older model and I don't believe it incorporated any of the 300/300.1 architecture. K Hayes would know for sure.
The Phi Beta integrated amp was based on the then Phi Master control preamp and the Phi 110 amplifier circuitry. The new Phi 300 amps are a further evolution and improvement of Kevin's already great amps.
well vac man ...count me in!
about to be the very happy owner of two phi 300.1's and i can't wait!
I have the the Vac 70/70 Ren Signature amp, and based in large part upon this thread, upgraded to the Accustic Arts Dac, with Amperex tubes, and also the Stealth Sextet digital cable. I also added the Stealth Dream PC. All I can say is wow, this is amazing; the sound quality is now at a whole new level. All the descriptive terms like huge sounstage, holographic, coherence, etcetera apply.

My thought had been all along to upgrade to the Vac Phi 300.1 amplifier next, but now I am unsure about proceeding. I hate to tinker with anything that is working so well. I am really feeling some satisfication in the music I have not felt or heard in a long time. On the one hand I wonder how much better it could be, but there is always the question of synergy, and any change can be a little unpredictable.

Can anyone describe again the benefit of going from the Vac 70/70 to the Vac Phi 300 series?
I can only speak to the 300.1. It is a WOW! I would keep what you have and enjoy it for as long as you can - when you get the itch, the 300.1 will be waiting. My system now sounds incredible, having been tweaked by Albert von Schweickert last week during RMAF. Kevin H. was also over to give his input as well. He was suggesting I might change preamps to the Ren Sig, but I decided to keep my Phi 2.0 because I really like the detailed presentation it offers. The point here is to enjoy what you have - the grass on the other side may not necessarily be greener, just different.
Just got a 2nd 300.1, and am monoblocking them to drive VR-7SE's to new, uncharted sonic nirvana. The sound is just amazing - the 7's are really opening up now, especially the 10" bass drivers. I can truly appreciate my system as its "potential" is finally getting realized. Its incredible what the extra power/monoblocks have done for imaging, depth of soundstage, separation(obviously) and sheer "weight" of the presentation. My system just grew cajones and I couldn't be happier.
Re-tubed 6 months ago with VAC's newer KT-88's and getting a slightly more organic and airy presentation. In addition, they are dead quiet and supposed to be much more reliable than the previous iteration of KT-88s used by VAC. Curious to see if anyone has acquired the new 440s, VAC's newest statement amps and can offer an opinion.
Do you happen to know what the manufacturer of the new Kt88 tubes are? The previous manufacturer, which I have in my VAC Musicblocs, was Shuguang.
Sorry - I don't have the answer - that would be a Kevin/Brent question. It's a subtle improvement, but its there, at least in my system. Definitely worth a try, IMO, if you don't already have them.
I might try out a quad of them when I need a new group. I doubt Kevin would want to tell who the manufacturer is as he has the VAC logo placed on them. Those in the know about tubes can tell by its construction who the manufacturer is, though.
Kevin does not and never has struck me as being secretive about anything. I would ask he or Brent. I'm pretty sure they told me - I just don't remember (sigh - it stinks getting older... :-))
So what is the difference between the Vac Phi 300, Phi 300.1, and Phi 300.1a?
So what is the difference between the Vac Phi 300, Phi 300.1, and Phi 300.1a?
Erndog 08-10-14
I asked Kevin several years ago and he said the main motivation for 300.1a is improving the methodology in building a more consistent product. 300.1 and 300.1a SHOULD sound the same but he admits there are reports they sound different in the field.
Ok that's good to know. Thanks!