The Minute 45 Amplifier by SAC Thailand

Tube selection

The Minute 45 lists for $2,300 with a standard input and rectifier tube included. It doesn’t come with any 45 tubes, so you need to order a pair from SAC Thailand along with your amplifier or find your own source of 45 tubes. The good news is that the selection for high quality NOS 45 tubes are much larger than say 300B tubes, so you shouldn’t have any difficulty sourcing them.

I was given two different 45 tubes to use with the Minute, a pair of Sophia Princess 45s and a pair of Super Silvertone 45s. The Sophia Princess was a very mellow sounding tube with big soundstage and excellent midrange clarity, and overall the smoother sounding tube. The NOS Super Silvertone was a very thick sounding amp, with thick punchy lows, but not as smooth or as clear as the Sophia Princess.

For the input tube I had three pairs of 6SN7s: two RCAs in Smoked and Clear Glass versions, and a Sylvania Chrome top. The only thing I can remember is that the Smoked Glass RCA sounds warmer and fuller than the Clear Glass RCA and Sylvania Chrome top. The Minute 45 definitely has a mellow signature built into the amplifier, and I felt that better results are achieved when I don’t try to fight that character but chose tubes that has the same character as the amplifier. In this case the 6SN7 RCA Smoked Glass and the Sophia Princess 45 are the tubes I use the most for the Minute.

I actually got plenty of different rectifiers to play with. The most impressive looking is the Emission Labs 274B, used for the photo session here due to its big and imposing look, actually ranks lowest in terms of sound quality. A NOS Mullard GZ37 pair was significantly better, and the GE GZ34 is the best rectifier of the bunch (you get a clearer sound top to bottom and a more spacious soundstage). The last rectifier that I had the chance to listen to is a pair of GE GZ34s, but this time in metal base version. This rectifier is even better than the glass base GZ34, offering an even more improved soundstage, but it also made the sound even mellower than when I used the other rectifiers.

End Words

The price of the Minute 45 makes it comparable to the WooAudio WA5LE (headphone amp only version), the Zana Deux, the Apex Peak + Volcano, and Cary’s popular Xciter headphone amp. Features wise, the Minute and the Xciter offers speaker outputs, though Minute’s 1.5 Watts output makes speaker selection extremely critical.

Technicalities wise, I think the Minute ranks up there with the best tube headphone amplifiers upwards of the $2,000 tag. The analog sound naturally lends for a more grainy soundscape, somewhat like the Zana Deux and Cary Xciter. These are very different than the WooAudio and Apex Peak sound, which are cleaner and more dynamic sounding. The Minute 45 is more refined and smoother than the Zana, though the Zana’s more upfront and forward sound would appeal better for the typical Rock and Blues crowd. The Minute 45 on the other hand would work very well with vocals especially female vocals.

Though I can recommend the Minute 45 wholeheartedly, I do think that it is quite a specialized amp focused for mostly mellow female vocals. I can’t imagine listening to Classical tracks which require a more dynamic presentation and stronger bass impact. Rock fans would probably be best looking at the Zana Deux or the Apex Peak as both amps have the pace and the attack to suit Rock music.

Thanks to Drew for the Minute 45 amp loaner, and Obee for the WooAudio WA5.

Tubes used for review
  • Driver tube: 45 Sophia Princess and Super Silvertone
  • Input tube: 6SN7 RCA Smoked Glass, RCA Clear Glass, Sylvania Chrome Top
  • Rectifier tube: GE GZ34 Glass and Metal Base, Emission Labs 274B, Mullard GZ37


Gear used for review

Sennheiser HD800, HD580, Hifiman HE-6, HE-500, Audez’e LCD-2, AKG K1000, Audio Gd Ref 7.1, KingRex UD384, CEntrance DACport LX, Hifiman HM-801.


minute45_14 minute45_12 minute45_11 minute45_10 minute45_09 minute45_08 minute45_07 minute45_05 minute45_06 minute45_04 minute45_02 minute45_01

3.6/5 - (15 votes)


  • Reply January 16, 2012

    Lieven V

    Nice one Mike, I’d want one just for the looks!

    • Reply January 16, 2012


      L, I can send you the amplifier as JPEGs. 

  • Reply January 16, 2012

    Hau Nguyen Dinh

    can you provide the high res jpeg ? beautiful pictures here 🙂

    • Reply January 16, 2012


      Any specific requests? Give me time and I’ll try to make the files available. 

  • Reply January 16, 2012


    Mike this are by far my most favourite photograph work of yours… beautiful… nice review as well, but I cant afford the amp so I pay more attention to the picts lol..

    awesome job Mike. make a high res wallpaper please…

    • Reply January 16, 2012


      Thanks for the compliments. 

      Any specific requests for a high res wallpaper file?

  • Reply January 16, 2012


    Great review, very helpful to get some differentiation on some of the tubeamps sound character. I´m close to buying a HiFiMan HE-6 and I listen to a lot of jazz vocals and some electronic lounge music. Mostly medium  tempo music and want my black background. Do you think Woo amps would work well on that combo ?   

    • Reply January 16, 2012


      For Jazz vocals and Electronic lounge I think the Audez’e LCD-2 would be the better choice. The HE-6 and HE-500 does good Jazz and vocals, but I wouldn’t recommend it for Electronic lounge. 

      Try the Burson amplifier for the LCD-2.

  • Reply January 16, 2012


    I still am at a loss as to why anyone would spend $2000 on a headphone amplifier to distort (yes, that’s the correct word) the source material in a nice way. Isn’t an amplifier’s job accuracy? Why do you want to add salt and pepper to that perfectly spiced dish?

    • Reply January 16, 2012


      How do you know if your source material is a perfectly spiced dish?

      • Reply January 16, 2012


        My point is that knowingly buying a headphone amplifier that distorts the sound is akin to saying that you know better than the chef (e.g. the artist and producer). Plus, you’re stuck with only one “spice”–that is, the sound of the amp. You wouldn’t put hot sauce on ice cream, would you?

        • Reply January 17, 2012


          You need to understand that the source materials are never neutral to begin with. Nobody puts sauce on ice cream, but what about pizza. People like different toppings to go with their pizza, and people add different amount of hot sauce on their pizza.
          I appreciate your effort to contribute here, but you really need to go out and listen to different recordings. There is no standard on neutrality even on the recordings so your point is rather naive.

          • Reply January 17, 2012


            OK, I think I understand where you are coming from: I need a *collection* of amps depending on the music I’m listening to and the color I want to add to the music. I’d better start saving up for my jazz amp, my male vocals amp, my rock amp and my classical amp. But I’d have female vocals covered with this amp, apparently. Oh, and by that logic, I will likely need a separate pair of cans for each amp.

            I will concede that my goals are very different from anyone who’d consider this amp and leave it at that. I prize accuracy, something that this amp obviously doesn’t achieve very well (since there are apparently large sonic differences from other amps).

            Another concession I’m willing to make is that I don’t understand many of the adjectives used here. Among the ones I have problems with are: “analog sound,” “grainy soundscape,” “slow paced,” “pace,” “attack” and others. I will have to study up, as my grasp of flowery adjectives is clearly lacking.

            With those concessions, I will not make an “effort to contribute” any more, as my contributions are obviously “naive.” It’s been interesting.

            • Reply February 25, 2018


              You would, instead, choose to describe the particularities of the human hearing mechanism in terms of voltage swings, current delivery, caps, and quality of parts ?
              How much of the review, or reference point to know how the amp sounds would readers be left with there ?

              I am a huge proponent of the factors mentioned, the quality of the build, parts, how the circuit is solved, implemented, the longevity of the parts, the ease of repair and service (can’t beat point to point there, I suppose, or the upgradable amp with easily replaceable ever-ready-on-the-market parts).
              It is certainly a very important element, as much as the sound quality.

              The reviewer, however has the task of conveying how the amp sounds and he has tried to do his job as good as he could.

              I wouldn’t mind for one a dissection of every amp and qualified opinions from the people with vast experience in tube amp design, and amp design in general.

              The question to me is how that all of the critics of these reviews do not make their own site where they give their honest opinions in professional and punctual manner.

              There is also one other aspect – with the plethora of the headphones available at the market these days, there is (for the consumer) an important element of the synergy between the amps and certain headphones.

              I am not going even to go in the tubes vs. solid state debate here, not more than saying that in the audiophile community there are still ever present misconceptions about human hearing, one of the most famous (from the “sceptics”) is the audible frequency range and how human hearing and feeling the sound really works.

        • Reply January 17, 2012

          Don Vittorio Sierra

          Actually in the grand scheme of it all, you do know more than the chef  🙂 and no piece of equipment or recording is really perfect anyways… thats why we have sites like these where stuff is reviewed 😀

        • Reply January 20, 2012

          Michael Nguyen

          Depends on the chef and hot sauce. Chilis are known to be paired with chocolate. How does this equate to audiophilia? It’s all down to preference.

    • Reply January 18, 2012

      Brian Fu

      Nice generalization there, good chap. 

    • Reply June 10, 2017


      The whole point of buying a certain amp is to match a certain headphone (transducer) you like, and complement it. Dead accurate amp, or perfectly linear such doesn’t have to be neither fun to listen to with a certain can (with similar traits); there are number of solid state amps which, when coupled with the “right” headphone prove this point quite well.

      I had a chance to audition a tube amp, headphone tube amp, and it leaves whatever solid state I have heard thus far miles behind it.
      There are number of elements accounting for this (in the amp itself) but the implementation of the tubes is the decisive one.
      When implemented well, they do not distort the sound in such manner that it is comprehended as a distortion, but add that flavour (second order harmonic disto) that pleases the human ear.
      Other way of looking at it is that solid state might rob us of something we otherwise hear in nature and like about the sound.
      Sound is analogue by it’s nature, transistors are discrete components.
      Question of the cost of the amp is the one that bugs me as well, but it comes down to the nr. of the units offered, interest of the potential market, cost of development, quality of the components and feasibility of the business model.
      To the most of us ordinary mortals the price of these amps is a frustrating point; but for less than half of the cost of this amp there are some good tube amps on the used market, and even brand new ones.

  • Reply January 17, 2012

    Don Vittorio Sierra

    Wow, I love 45 tubes… On a very high efficiency speaker system, I prefer the 45 sound to the 2a3 and 300b. Well I guess I can’t say I have compared the 300b and 45 on the same amp though since they are not interchangeable but there are amps where 2a3s and 45s are interchangeable and on those occasions, I definitely preferred the more spooky realistic feel of the 45s 🙂

  • Reply January 17, 2012


    So it seems like the minute 45 has the traditional “tube” sound with its mellow and slow pace with an emphasis on mids which leads to a “romantic” sound. Compared to the WA5 which is more like a solid state with a freakish black background, still warm sound but with a good PRAT? And by traditional tube sound i mean, you know tubey i guess. haha

    Could Woo Audio amps be considered having a hybrid sound? having characteristics of both tube and solid state.

    sorry if this comment seems more geared for WooAudio rather than the Minute 45 but im really interested in the WooAudio amps and its nice comparing them with other type of tube amplifiers. 


    • Reply January 17, 2012


      I sort of understand what you’re trying to say, as in the Woo having a hybrid solid sound & tube sound combination. But I guess saying that would lead into more problems in the future as solid states themselves come in very different sound signatures. I’ve listened to a solid state amp that sounds very mellow similar to the Minute 45 here. So what exactly is a solid state sound? 

      I hope you understand what I’m trying to explain here. 

  • Reply January 17, 2012


    Guys I’ve been terribly busy updating the Recommendations page, but I think I can have some high res photos from this article up tomorrow.

  • Reply January 22, 2012

    Austin Morrow

    Very intuitive and interesting review, Mike. I’ll have to say though, that is one of the most beautiful and sleek looking amplifiers I have ever seen. I don’t know why I’ attached to it so much, maybe it’s the tubes, maybe it’s the design, but it sure is a beast of an amp, to say the least.  I have a feeling this would be a good combination for something like the HD800 if you wanted to have amore full, lush, and enjoyable sound experience, no?

    • Reply January 23, 2012


      Yes it’s very good for the HD800, Austin.

  • Reply February 13, 2012

    paul b

    i cant believe my luck !!!  I have been on the lookout for a tube amp to warm up my HD800’s plus i listen mostly to female vocals BUT best of all it is made in Thailand and therefore my patriotic Thai wife wont complain about me buying it :))

    • Reply February 13, 2012


      That’s awesome, Paul! 😀

  • Reply August 28, 2012


    The only question that I can help answer is that I think the Woo WA5 (I don’t think you’d be comparing the WA6 to the Minute 45) would work better with a wider range of music.

Leave a Reply

This site uses Akismet to reduce spam. Learn how your comment data is processed.