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If you love SET amplifiers, boy do I have speaker for you.

I have had in-house for the last six weeks a pair of speakers that I'm reviewing for hometheaterreview.com from NSMT Loudspeakers, located in North Carolina, that are a perfect match with SET amplifiers.  I love SET amps.  However, historically I'm not a fan of single driver designs (rolled off high-end/lack of bass) or horn designs (I find them to have coloration that annoys me after a short while) that are normally used with beautiful sounding SET "Flea Watt" amps.  I have reviewed both types of speakers and they were good, but not keepers for me because of the above stated reasons.

The NSMT Model 50 is a small very attractive floor-stander which has an sensitivity rating of 101 dB and never dips below 8 ohms.  It is a three driver MTM two way design that loads into a double transmission line and really reaches down to 35Hz to 20 kHz in my room.  This is the third speaker I have reviewed from NSMT, the other two were wonderful music makers, and shows what a talented designer that Erol Ricketts is in all his designs at applying his unique version of transmission line loading. 

Now, the Model 50 sounds terrific with high power SS or tube based amplification.  But what has been enchanting for me is when I drive it with either a SET 2A3 amplifier, around 3.5 watts, or my Linear Tube Audio MicroZOTL as an integrated using the NOS 1940's Tung-Sol 6SN7 black glass oval plate tubes which produce only around 1 Watt.  With either amplifier this speaker completely disappears, the beautiful colors/timbres just float out and 3D chunky images of the players fill the soundstage.  However, because of the very high sensitivity of the Model 50 and its transmission line loading the foundation of the music, true deep bass, and overall dynamics/dB levels are hard to believe.

So, if you have or always wanted to try out a SET amplifier this speaker is a great choice.  The Model 50 retails for $1,800.00 a pair, so they are very affordable to team-up with your SET amplifier.  If you want a lot more details just go to NSMT-loudspeakers website.    
teajay
charles1dad's avatar
charles1dad
10,250 posts
 
Hi Bill,
Merry Christmas to you and your wife. I remember when you all left Indiana for Tennessee, 5 years already.? With all the hiking you’re doing through the Tennessee hills you must be fit as the proverbial fiddle 😊.
I am happy to hear retirement has worked out so well for both of you.

Those 101 db/8 ohm speakers do swing open the doors of possibilities as teajay alludes to. In terms of the low power amplifiers IMHO the Frankensteins are going to be very tough to exceed . Many very good amps in this genre, but better? That’s a different story.
I bet these NSMT speakers are ’quite’ good but wonder how they’d fare against your Triumphs Extremes II ? This discontinued Coincident model was exceptionally good and a fine effort from Israel Blume.
Charles
aricaudio's avatar
aricaudio
273 posts
 
@charles1dad much appreciated as well! I admit I hopped on the fast track towards truly studying true SET designs. I now have acquired several boxes of "tinkering" parts where I’ve been able to swap out filament transformers, diodes, caps, chokes, etc. and listen to the results in real time. AC filaments on single-ended DHT’s generally hum but sound lovely everywhere else, whereas "down and dirty" DC filaments are dead quiet- but sound sterile and lack dynamics. Doing a well-implemented DC filament on a SET requires complexity to get that AC liveliness and DC quietness and could fill a small amp chassis with just those parts! But when done right, there simply is no comparison in a well done SET with all of it’s requirements in place! On the other hand, if I want a great sounding amp right out of the gate on a budget, the Beam Pentodes fit that bill. Each one has it’s place and does what it does very well if designed correctly.

Also of great note are many recent high-efficiency multi-driver designs (like these speakers TeaJay has mentioned) that can allow these pure low-wattage amplifier designs to work their magic. It opens up hundreds of options wrt amplification choices. 

 Happy Holidays! Aric
charles1dad's avatar
charles1dad
10,250 posts
 
Aric
Numerous very established/highly respected SET manufacturers has written the same regarding DC versus AC heating. You are definitely on the right track in your findings/conclusions. Some believe that the 45, 50 and 2A3 ’may’ successfully allow AC heating (withoutt hum issues) but is more difficult with the higher powered 300b tube. Many listeners agree with you, poorly implemented DC heating can sound lifeless relative to AC heating.


BTW I agree with your comments regarding the availability of efficient easy to drive speakers. A friend of mine recently acquired a world class level 2A3 SET. He is very pleasantly impressed by the many good options in the Hiigh End marketplace for these types of speakers. 
Charles 
brownsfan
1,508 posts
 
@charles1dad Merry Christmas to you and yours.  Don't want to veer teajay's post off course, but you do see my dilemma clearly.  The Franks are special amps, and I recently found a used pair of EML XLS tubes which are a step up from the Psvane T's that I used after failure of the Elrogs.  The Franks really make the Triumph Extreme IIs sing, and those little monitors were woefully under appreciated in my opinion.  I have little doubt that a bit of work on the crossovers will elevate them considerably.  Beating that combo without spending a lot more money than I can recover from them on the used market is a long shot.  But I have a long standing longing to find out what the hype is all about with 45 or 2A3 power tubes, and those NMSTs look like a steal at $1800.  It is really an intriguing (perhaps ingenious) design.  I've said this before.  There is just too much good stuff out there.  
t_ramey
632 posts
 
Merry Christmas everybody. I got a question about the 45/2a3 type amps in regards to driver size. Even if you have a speaker that is very high in efficiency but has say 12” or 15” drivers, does a low watt amp still work its magic or would it struggle?
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