Mastersound 300b Compact-thoughts???


I am considering this amplifier and wondered if anyone as experience with it? Also, it seems from what I can read it is SS rectified, can anyone confirm this, or am I missing something?


Many thanks




I'm having Coherent Audio 18s made currently, so investigating amp options that'll take advantage of their high efficiency (102dB

In my opinion based upon what I have learned about the Coherent Audio speakers you’re going to be exceedingly happy!! You are on the right course with regard to pursuing lower power but high quality built tube amplifiers. Stick with your plans as your speakers will allow this to come to fruition.


Mastersound is a very reputable manufacturer that’s been around for years and I believe that they build their own very high quality transformers. My only concern is that 15 watts per channel rating is unusually high for the 300b tube. The good news for you is that there are no shortage of other low power SET (Or push-pull) tube amplifiers to consider. You are “not “ going about this in a wrong manner.

Frank has explicitly designed and implemented his speakers to be superb partners with these types of fantastic sounding amplifiers. Have you determined a particular budget range for your amplifier? Take your time and you’ll have a splendid high efficiency speaker/low power tube amplifier audio system. My system is posted on this site. I went this route 14 years ago and there’s been no looking back.


@charles1dad I've seen your system - looks great! I'm sure it sounds even better!

I'm mostly hanging around the 8-10k range all-in as far as pricing goes.

With some of the 300b amps like this mastersound, can find them gently used with low miles for around $5500, which leaves plenty of room to get some excellent tubes, but the power output concerns make it a bit of a risky endeavor. Even Frank switched to using this as one of his rotating amps fairly recently from what he said, so I'm not sure he will have a lot of insight into long term tube life with it.

The allnic can usually be found lightly used for around the same price point as well, and that is rated at 10 wpc output, which seems a little more in the normalish range.

Triode lab would be if I decide to go the 2a3 or 45 tube route instead. I've been eyeing the 2a3 in particular. They're beautiful amps and look very well made.

The tektron amp I was referred to does allow for tube rolling with 45, 2a3, 50, but again, just concerned with the build quality. Looking inside them, there's a lot of wiring and components that aren't supported by anything but their connections. It feels sloppy to me. I know they have a pretty good reputation as far as sound quality goes, but I just can't get over that. Even a reviewer had to re-attach things in their demo model that came lose in shipping (!), which for thousands of dollars just shouldn't be happening IMO.

Ideally looking at integrated amps since I don't have a pre-amp and it's questionable whether I would have enough room to setup mono blocks. I probably could, but it would be pretty tight.


Your budget range will allow you to purchase an excellent quality amplifier. I’m much more familiar with the 300b genre than the 2A3 but I believe that either would work in wonderful fashion with your Coherent Audio speakers. Triode Lab uses Hashimoto transformers and chokes. I know that Allnic goes a different route with “permalloy “ iron in their amplifiers.

Allnic also believes a “bit” of NFB is desirable (Lower output impedance thus higher damping factor/DF).  I’m pretty certain that the Triode Lab is purist zero NFB. Does Frank feel the added NFB is necessary or a factor with his speakers? Allnic utilizes 6 db NFB. Anyway both of these brands are well thought of. With those speakers get the best amplifier you can afford. You’ll have superb sound quality for many satisfying years.


As an update here, I reached out to the US distributor of Mastersound, who reached out to Mastersound directly to get some clarification about my concerns on the 15wpc rating. Answers are below.

1. In speaking with MastersounD, they have given a spec at the “highest” voltage in electricity. For example, in the UK market, voltage is 220v, but in many cases, homes will have 230v or even 240v. In a more normal voltage like 220v, their power is more like 10-11 wpc. This Is still higher than what others are getting out of a pair of 300b tubes, but that is due to the in-house built transformers. These alone have been getting approx 30-40% more output of a tube as they are achieving 95% of the efficiency of the tube. The common characteristic sound of our amps are that they have more energy and dynamics than our competitors amps.

2. MastersounD regulates the 300b at a very “quiet” value without risks to the life of the tube. The 300b tube is a very delicate tube and especially during transport. That being said, they have many customers who are still on their original tubes after 20 years. It all depends on the quality of the tube.

it appears 8-10wpc is expected on 120v US power, which is more in line with what would be expected.