The Minute 45 Amplifier by SAC Thailand


Minute’s 45 amplifier comes from SAC Thailand, a small boutique audio manufacturer based in Thailand, famous for making world-class output transformers and transformer based volume controls. The Minute 45 is a custom build amp based on the Minute 300B (with the 300B tubes), so you’re not going to find it listed in SAC’s website. If you wish to, SAC can build you an amplifier that will accommodate both the 45 and the 300B tube (you only have to flick a switch to choose the tube to use), but according to them, best sound is achieved when you dedicate the design solely to one tube type, so this build is strictly a 45 tube amplifier.

Along with the standard 1/4″ TRS out, the Minute also comes with 4-pin XLRs for the AKG K1000 and speaker taps at the back with a power rating of 1.5Watts at 16 Ohms. On the front panel you have toggle switches to select gain level (Lo/Hi) and Impedance range (Lo/Hi). With the massive transformers, the amplifier and power supply are very heavy, each unit weighing roughly as heavy as the Woo Audio WA5 amplifier though having a smaller footprint. The build quality is super fine and definitely on the same rank as high end brands like Cary or Manley.

Sound Impressions

I think standard review statements like “it has a tubey sound” should be banned once and for all. The reason is that there is no such thing as the standard tubey sound. Comparing the Minute 45 to the Woo Audio WA5 (300B based) side by side reveals that the two doesn’t sound anything remotely similar. The Minute is very mellow, mid-centric, analog, very slow-paced, and absolutely romantic sounding. The WA5 on the other hand is clear, dynamic, and fast sounding.

Aside from the 300B (WA5) vs 45 (Minute) tube differences, the two amps actually use the same GZ34 based rectifiers and 6SN7 input tubes. However, the extreme contrast between the sound signature of the two amplifiers may be more than just the 300B/45 tube. It may be due to the character of the Silk output transformers used in the Minute, the choice of components in the amplifiers, or even the design of the amplifiers. But the one thing we can deduce from this comparison is that there is no such thing as the standard “tubey sound”. The WA5 and the Minute 45 are absolutely opposites when it comes to their sound.

I found that the difference in sound signature, the dynamic Woo versus the mellow Minute, the clean black background Woo versus the analog grainy Minute ultimately determines which amp would be best for someone looking for a high end tube amp. For instance, let’s talk about vocals. Often people ask me “Which amplifier is the best for vocals?” I found that the dynamic sounding Woo is the better choice for listening to Bocelli, Belafonte, and Diana Krall as it conveys the energy of the singer better. On the other hand, for singers like Norah Jones, Corrine Bailey Rae, or Tracy Chapman, the Minute 45 is the more fitting amp as mellow presentation fits very well the character of the vocals. It had the warmth and the silky smooth mellow voice, just the right character for these singers.

Another situation is when you want to play some Jazz music. The Woo has a clear dynamic sound with a very wide soundstage. Zero grain, a pitch black background, and each instruments having a very distinct spot in the soundscape. On the other hand, the Minute is about ambiance, the feel on the venue where the recording was taken, and the sound of the air combined with the grain in the master tape. It’s an absolutely different presentation here. Remember that romantic analog sound from the tube radio (if you ever listened to one)? That’s what the Minute is all about. Some people may prefer the black background soundscape of the Woo, but the Minute has the better depth, layering, and ambiance. In the case of Jazz music, I think either amps would work very well so it boils down to personal preference. The Woo for a clear dynamic voice, and the Minute for a warm and analog sound.


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The Minute 45 Amplifier by SAC Thailand
4.25 (85%) 4 votes

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

    • L, I can send you the amplifier as JPEGs. 

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

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

  • harsyafadilla

    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…

    • Thanks for the compliments. 

      Any specific requests for a high res wallpaper file?

  • Larry

    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 ?   

    • Larry,
      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.

  • Paul

    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?

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

      • Pleskinen

        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?

        • Paul,
          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.

          • Paul

            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.

        • 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 😀

        • 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.

    • Nice generalization there, good chap. 

  • 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 🙂

  • Eric

    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. 


    • Eric, 
      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. 

  • 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.

  • 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?

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

  • 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 :))

    • That’s awesome, Paul! 😀

  • Anonymous,
    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.

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