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.    
Hey teajay, how would you compare them to the Tekton open baffle speakers you reviewed a couple years ago?
Hey boxer12,

The Tekton open baffle model was a great speaker if you love planar speakers, but want more dynamics and pinpoint imaging.  However, I never tried them with a SET amplifier, my hunch would be it would not be a great match.  The Model 50 sounds great with the high power SS amps I have tried on them, but the magic for me is when they are driven by a great 2A3/300B SET amplifier.
This looks like a real find.  Driving a speaker with a 6SN7 is mind boggling.  When and where can we see your review, teajay?
Hey brownsfan,

It will probably go up on hometheaterreview.com in March sometime. 

To drive a speaker with a 6SN7 is "mind boggling" without losing overall dynamics/lower bass/dB levels and keeping the beautiful purity of tonality, transparency, and 3D imaging that a pair of NOS Tung-Sol black glass oval plate delivers to a system.  I find this tube to be one of the most musical sounding devices I have ever heard.  It's not quite as "cozy" as a 2A3 tube (which is my favorite tube to listen to in a SET amp), but boy it has its own virtues that draw you into the music.  Actually, I never had heard a 6SN7 used as a power tube until I reviewed the Line Tube Audio MicroZOTL and used it as an integrated amplifier.  
Thanks for sharing this information with the AudioGon community.
First time I’ve heard about this speaker company.  I think these speakers is what i need, the question is what 2A3 tube amplifier do you guys recommend that its price is under $2K?
I currently have a set of MiniMite Quicksilver mono amps with an output of 25 watts/channel. Will the MiniMites be an overkill for these speakers given that high sensitivity?
Hey Dan,

You should contact Aric (413-627-2543) of AricAudio who builds great tube gear at very reasonable prices.  If you look him up on different AudioGon threads you will read nothing but accolades about him as a person and the hand-crafted pieces he designs/builds.  I'm sure he would be able to build a 2A3 that would fit your budget. I have reviewed several of his pieces for hometheaterreview.com that would provide details about Aric and his designs. 

I have driven the Model 50 with a 200 watt SS amplifier and they sound great, so your Quicksilver amps would be no problem being a musical combination.    
Hey Teajay! Thanks for the referral and also the kind words and including me in this thread as being a source for amplification. Here’s my honest take on the question posted by @davidantonio . To get a 2A3 amplifier "done right", there needs to be special care and certain implementations to the circuit that do raise the cost over say a KT88/120 based SE amp. The reason being, is that a low cost 2A3- would actually sound worse than a low cost KT88 single-ended amp. For under $2K I would not recommend a 2A3 but rather a KT88 SE amplifier as less is required in that circuit to obtain killer sound. The reasoning (in short), a 2A3 or 300B being true DHT SETs is more complex to obtain good sound. Several things needed are: isolation of the filament from the cathode (as they are shared in the tube and need to be isolated so that no modulation occurs between them). A properly designed DC filament stage using chokes to avoid hum, and a hefty/robustly built driver to push the low MU and high voltage requirements at the grid really make a 2A3 or 300B "come alive" which costs more and are not possible to build at under $2,000. My price for a properly executed 2A3 would start at $3K and go up from based on the caliber of internal components are used. Not to deter, but if looking towards a 2A3 amplifier- don’t skimp! If budget is more modest- I would recommend my Transcend KT88/120 amp. Anyone interested- please feel free to reach out to me with any questions at aricaudio@gmail.com or through the Contact Us on my site at: www.aricaudio.com. Best wishes and Happy Holidays to all! Aric
@teajay I could not agree more with respect to your comments regarding the virtues of the 6SN7, though I have not had the opportunity to evaluate that Tung-Sol oval plate to which you refer.  There are some great NOS 6SN7's that are still affordable. I have never really been satisfied with the musicality of a system that did not have the 6SN7 somewhere in the chain.  

I might take a look at the MicroZOTL amp.  This idea really fascinates me.   I will be looking for your review.
Hi teajay,
have you listened to Eric's Tekton Perfect speaker? I've been thinking about purchasing them to mate with my SET. Best, mikirob.
To answer your questions:

1) Don't know what drivers Erol uses in the mastering series.
2) I'm going to get in for review Eric's new Prefect SET speaker next month for review. Knowing Eric's creativity they will be wonderful and offer SET amplifier owners another option at a very reasonable price.
Thank you teajay. Looking forward to your upcoming review of the Perfect. Looks as though reasonable priced speakers for us SET lovers is now happening. Best, mikirob 

P.S. Hi Brownsfan, trust you are enjoying retirement. I recently joined the geezer crowd. Your Browns are starting to look like an NFL team again.
Looks like the driver is a SEAS coaxial made with TPX and soft-dome tweeter, available from Madisound.
 Hi and I really appreciate your candor and advice. I'm a confirmed DHT SET aficianodo.  However I've advised people that if you're going to utilize these special tubes, do it right. You are absolutely correct in that you can't skimp on the quality of parts/transformers,  you're wasting time and money. 

You'd definitely better served with a indirectly heated Pentode than cutting corners trying to build/buy a DHT SET cheaply.. Now if done right DHT can be genuinely fabulous. 
Hi Teajay, 
I've heard the LTA Micro used as a 1 watt integrated amp driving the Tekton Double Impacts.  It was a good sound but bettered by Aric Audio 300b SET and the Coincident Frankenstein. I was pleasantly surprised by the result of a 6SN7 as an output power tube.
@mikirob Congratulations on your retirement!  As for Geezerhood, that is more a matter of lifestyle choice than employment status.  I am still enjoying retirement.  We chose wisely with respect to our relocation to eastern Tennessee, and I think we also chose wisely with respect to the decision to retire early.  It is hard to believe it has now been almost 5 years.  As an added bonus, now I can actually really enjoy watching my Browns again for the first time since the late 80's. 
@charles1dad, Thanks for your summary of the LTA Micro vs the Franks.  I'm not really interested in building a 3rd system, so anything else I might bring in would need to displace the Franks/Triumph Extreme II combo in the second system.   A low cost 101 dB efficient speaker like the 50's opens up some avenues for exploration, but I want to choose wisely.
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.
@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
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. 
@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.  
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?
@t_ramey - The amplifier won't struggle with larger drivers provided efficiency and impedance are all in check. Within the power limits of the amplifier of course. I receive this question a lot, and what it really all boils down to are listening preferences. If you listen at modest volume levels and listening to moderately dynamic music, then a 2A3 or other lower powered SET amp will work wonders. On the flip side of that coin, if you're looking to move lots of air with multiple 15" woofers playing fast-paced guitar heavy music with significant bass staccato notes in the 30 hz range then you will need more power. I have driven everything from 15" high efficiency horn-tweeter designs, 12" 3-way designs and 8" 2- way designs with ribbon tweeters without issue from as little as 3.5 watts. 90% of my listening is done where you have to talk loudly over the speakers, the woofers will pressurize and rarify lots of air and the room is filled with sound. However if Slightly Stoopid, Sublime or Bob Marley come on and I want to up the volumes to party levels- it runs out of steam and mostly in the bass first. For music like the latter- I much prefer Push-Pull. I hope this helps, Aric
99db Klipsch Heresy IIIs with 2 REL subs, and a Dennis Had Firebottle SE amp...an inexpensive path to mojo all day.

Thanks for the reply! That’s great info to be mindful of as I just took delivery of some nice klipsch speakers and would love to add more tubes to the mix at some point. 
Hi @teejay did you happen to test these with the pass labs XA25 amp? Just wondering your thoughts.

Hello tdwolf1414,

Yes, I have tried three different SS amplifiers, including the XA25, and the Model 50 delivers superb results with these much higher powered amps.  With each, the speaker's very high level of transparency allows the different amplifier's slightly different sonic signature to be easily heard.

So, I want to be very clear, this speaker offers wonderful results regardless what I drive it with.  My excitement over the Model 50 is that it is full range transducer that allows me to use my SET 2A3 based amplifier to hear the SET glory with no short comings at all regrading dB levels, bass extension, or a rolled off high-end.  As I stated before, I have auditioned/reviewed single driver designs and horn speakers, all of them were much more expensive, and none of them were keepers for me.   
Hi Bill.,
 Ok I understand your objective,  exploring the specific category of  the 45 and 2A3 tubes. In that case the NSMT speaker seems an excellent place to start the process.
@t_ramey - You’re very welcome and that’s most excellent! I think Klipsch speakers of the large/high efficiency variety are great candidates for SET amps!

@teajay - It sounds like these speakers are a winner, and nonetheless a very affordable conduit to allow the speaker/amplifier magic to really shine.

Best wishes and Happy Holidays to all! Aric
  101 db 1 watt softdome tweeter does not exist 8 inch woofers good to 35hz at 101 db also do not exist 
"...101 db 1 watt softdome tweeter does not exist 8 inch woofers good to 35hz at 101 db also do not exist."

I must confess I'm also intrigued by the 101dB sensitivity specs. Like to better understand how's that accomplished.
I do not believe the published specification of 101db/w for a second. I do not see how it is possible to crossover a 1" soft dome with 8" paper cones and retain that sort of output, all without halving nominal impedance.

@teajay do you have anything negative to say about them? Your threads about products you are 'reviewing' are always quite generous
Hey Guys,

I'm not an electric engineer so your belief that this speaker's spec of 101dB just can't be so I'm not going to challenge on theoretical grounds.  Why don't you contact Erol to discuss this with him.  

I'm driving this speaker either with 1 watt or 4 watt SET amplifiers with no difficulties regarding volume levels, bass extension, and overall dynamics.  I get easily over 100dB if I really want to listen that loud, even though I rarely push it to that volume level (sitting seven feet off the front of the speakers).  So, whatever Erol creatively did in his design to get an extremely high sensitivity obviously works beautifully.

I only post here on the GON when I find superlative products that offer "great bang for the buck" that I would want to own and use in my own system.  So, the short answer is no, even though no product is prefect.
If I had not fallen in live with the 833-A SET and Magnepan speakers I would want to try this design. The NSMT is a very attractive looking speaker, not only at modest price but ideal for inexpensive to build yourself small SET amps. They draw less current than my amplifiers do.
A few years back I had James Burgess build me a 2a3 amp .. To mention a few of the parts were the James transformers.. the bigger ones.. that are squarish in shape (better bass) --not the typical round ones that are often used which cost less. . Some high end silver and oil caps, ,etc. choked p.s. etc. My bill came to just under $2k. Some of you may have heard of Mr Burgess.. His creations come up infrequently. He was able to deliver the amp to me because he visits the bay area at times. However, I no longer have the amp as I sold it to lighten the load for a move I made out of the bay area. It simply should not of been sold especially considering how good the build was and how good it sounded. James is a jeweler at his day job and does this as well.. Oh, I almost forgot. Design was based on the Baby Ongaku.. I forget who designed that but the article of that amp is online. I forgot also James’s name.. Had to search through email. Bette Davis said getting old is not for sissies. I feel like a sissy more and more. lol. btw--I dont have James’s contact info any more because... no,, I might have his phone should anyone be interested. He’s in southern Cali and probably can be located online as well. btw--good for the poster who sussed out what drivers were used. Seas much better of course than some of this stuff that passes for drivers.  In addition -- I have quite a sensitivity to hum issues concerning tube amps..   Operational hum,,coming from the amp itself not the type of hum that can come through the speakers..    The operational hum when its there can happen for a number of reasons.  Almost every tube amp I have had both P/P and SET had issues with hum..  The Burgess 2A3 had no issues with hum..  and as for tube rush--the minimum if any at all.   That's quite a build! 
Teajat do you have any further thoughts in the speakers? Sounds like it would be perfect for my 45 amp
Hi davidobr,

My review will be out shortly with all the details on the Model 50. Yes, I'm driving this pair with a 2A3 SET amplifier and love how this system sounds, therefore they would sound superlative with your 45 amp.
Hi everyone,

My review on the Model 50 went up today on hometheaterreview.com with all the details about this NSMT speaker's wonderful performance. 
Very curious why you did not compare them to the Tekton offerings you've reviewed? Seems like an obvious comparison. Since you didnt ...........? 
Hey mofojo,

Since the Model 50 is a floorstander, not a stand mount, it would not be an apple to an apple comparison with the DI Monitor.  Also, the DI is priced $2,100.00 more then the NSMT, so it's not in the same price range.

I will be getting very shortly the new Tekton Prefect SET model for review.  This speaker is built to be used with SET amps and is priced at exactly the same price as the Model 50, so this will be an apple to apple evaluation.

I'm really interested from your HTR review that the Model 50 seems to throw a massive and immersive soundstage...which is something I really value. 

One question I have is whether their deep bass also translates to that mid bass slam factor that really furthers the sense of a "live" performance....in other words, some loudspeakers can go deep but never sound alive often because of lack of slam or a recessed midrange...so any thoughts you can provide would be helpful.  Thanks

Hey snapsc,

I believe what you are referring to is what I call a "leaness" in the lower midrange or upper bass region which takes away the foundation of the music.  The Model 50 is not lean in this region at all.  They sound "alive" with great punch/energy. 
Thanks... teajay... seems like these may be a nice step up from my Lores... which are no slouches. 

On the other hand the tekton Perfect Set should be interesting also.  The “12” transducer should punch pretty hard so I suspect it will be a comparison of midrange, topend, soundstage and overall musicality. 

Hopefully they hit your doorstep soon and you can post a few thoughts. 
Its not possible for a 1/4 transmission line speaker using  8 inch driver and tweeter in a small box to be 101 db... something is not exactly right.Or they have invented a new driver. which i doubt based on they only had one pair in stock to sell and that pair was not even finished.

I called the company a few weeks ago, he would not answer any specific questions about the speaker design in any kinda detail.  

Hope batman1971 will hear the Jamaica speaker for himself sometime. There is also a review of the new NSMT Model 100 on 6moons that compares the Model 100 to the omnidirectional MBL Radialstrahler E101 MKII:https://6moons.com/audioreview_articles/nsmt/4/
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