Review: Acoustat Trans Nova Twin 200 Amplifier

Category: Amplifiers

Lived in S. Florida during the time Acoustat was in business there and knew many of the principals there. Talk about a bunch of fanatics dedicated to high end audio,would be a gross understatement. The folks at Acoustat lived,breathed,slept,and played as hard as anyone in audio.It was truly their whole reason for being. The products they brought out were astounding and have truly stood the test of time.

One such product was their first power amp, the Acoustat Trans Nova Twin 200,also known as the TNT 200. For several years they auditioned practicaly every amp out there. Knowing full well that the amp would have to be exceptional in order to drive properly their range of electrostatic speakers,with their widely varying ohm load. Frustration after frustration ensued with each amp they auditioned. Those that could drive them just did not have the sonic signature the speakers needed. Consequently those that did have the signature they were seeking just did not have the current to do the job.

Face with this dillema,the only recourse was to build their own amp. Armed with the things learned in the auditioning the other amps,they now had a focus on what to do. The Acoustat TNT 200 was to be a fully MOSFET amplifier from input stage to output stage. Probably the first to use this type of topolgy. No one knew their speakers better than they did,so the amp was built knowing it drive the Acoustat line of speakers.

The first review of this Amp came from "The Sensible Sound" #17 Spring 83 issue. In the comparison it was matched against the Van Alstine Transcendance 400.

While I will not to into excessive detail here,the review on the Acoustat was most favorable. The TNT 200 has a more discernable sound than the Transcedance. Percussion has a seductive silkiness that is very pleasing.The mid range the amp excels with great detailing,with a very wide sound stage.While the top end frequencies,have a clarity and depth not often found.

I have used many different amplifiers with different Acoustat speakers. None of them for me really filled the promise. Finally located a TNT 200 and had a friend of mine who use to work for Acoustat rebuild the amp and add all of the updates.

Once you hear this amp driving a pair of Acoustats,you will then know why all other amps pale in comparison. This amp has the muscle,transparency,sonic signature,depth,and clarity that Acoustat Speakers need. And at prices in the secondary market are a true steal.

So if you have Acoustats or any electrostatic planar speaker here is your amp. The search is over. As far as conventional speakers go this amp will drive them with a verve that will astound you.

At the very least this amp will make you want to listen to every album or CD you own. A true glorious delight.

Associated gear
Acoustat MRP Pre Amp. Acoustat Model 2 Speakers.Denon DP 61 F Turntable,and Denon DCM 370 CD Player

Similar products
Threshold,Forte,Audio Research,Citation,Adcom,etc

Hi Ferrari,

Great review, thanks! The Acoustat Trans-Nova Twin 200 was a Hafler design, and I believe was manufactured for them by David Hafler. Thus it is an improvement over the DH-500. One of the things that made it so great was the capacitance, it had 100,000uF of capacitance. This tends to be one of the major factors which determines whether or not an amp can drive a pair of Acoustats.

Older Stasis amps had issues, I understand, with Acoustats. The S/500 supposedly did well with them, I am told, and it had the requisite capacitance to get some bass out of them as well.

The Acoustat TNT 200 was not a Hafler design. It was designed by James Strickland and if memory serves me correct Frank Van Alstine had some input with the design.The TNT 200 was built in the Acoustat factory in Ft. Lauderdale,Fl. Thanks for the remarks - Much appreciated.
I haven't heard the Acoustat, but Jim Strickland eventually landed at Hafler and designed the 9300-9500 series Trans-Nova amps. I had an original 9500 for over 8 years. It is a very good amp. Not often available used, but a good value when available.

Hi Ferrari,

Thanks, poor memory I guess.. I believe Van Alstine did the phono sectin design for several of the Acoustat preamps, but as far as I know had no input into the amps.
I have a pair of Acoustat X's with the servo charged amps built into each speaker. While they are old and yes, they don't do so good with the bass, I use them in my screening room with my High Definition Projector. i use only two channel.

They are quite the curiosity and they work really well. For further information on Acoustat, try doing a web search on just the word, 'Acoustat'.
I bought this 20 years ago and there preamp. to drive there 2+2's. Still in full use today with NO problems except for the power on-off switch, it is stuck on so i am using a power strip with a switch on it. I use the to drive a pr. of Ohm Acoustics Walsh 4XO's, great sound.
I have been trying for quite some time to get schematics on this stuff. If you do a web search on 'Acoustat', you will find an Email address to some of the former engineers. they might reply.

I recently was able to one of my Acoustat X amps as I own it's twin an we were able to compare and find the problem. Good luck.
Not that it was worth it, resale is nothing on it, but for the heck of it I decided to mod a TNP preamp. After hearing a plethora of disparaging comments about it, and assuming that it was not such a horrid design after all... Well, I was completely right, the original caps and bypass caps used in the TNP suck, use RT or RTX caps for bypassing, and Black Gates in the signal path, and Nichicon Muse caps in the supply, replace the 1N400(X) cap with UF4007’s and this preamp will hold it’s own against the big dogs, and smoke the later Acoustat preamp, unless you mod it! :-) I did not do the phono section as I just wanted to prove a point, and as I had wasted quite enough money on it. If I was not crazy about remotes, I would use it…
Interesting. In response to the old post regarding how much of an improvement the TNT-200 is over the DH-200, I can sum it up in one word "INCREDIBLE".

I have used and tested the following amps for powering my Acoustat Model 3's w/Medallion transformers:

Hafler DH-500
Hafler DH-200
Perreaux PMF-2150B
Threshold S/300

Several years ago I became interested in replacing my Hafler 500 with a Perreaux PMF 2150B. Out of the amps listed above I had found the 2150B had much better detail and was a significant upgrade in overall sound. During my quest, I found that used 2150B's had become popular among the "e-Bay" audio speculators. So much so that they were priced much more than they were worth to me. I did a bit more research and came to the conclusion that "on paper" if I could find a TNT-200 it should provide a similar upgrade in sound quality. Well, I found one and bought it at a very reasonable price. What happened next was nothing short of awesome. I just couldn't believe how good the TNT 200 was. It was amazing. There was so much detail I was dumbfounded. CD after CD, there were details that I had never heard before. Amazingly on some you could hear people whispering in the background very clearly.

After I bought the TNT 200, I sold the Hafler 500 for $100 more than the Acoustat. Hafler amps are great, but the Acoustat TNT-200 is so good that you would have to pay at least $5000 today for an amp that could even compete against it. In my mind, an Acoustat TNT-200 in working order is priceless.

I hope that answers the question albeit a year later...

BTW, the DH-200 has better sound driving my Acoustat Model 3's than the 500. I bought a used 200 for my son's birthday awhile back and after listening to them drive the Model 3's I tried trading my 500 for it, but my son would hear none of that. :-)
I have a TNT 120 which does not like being connected to my ESL (Innersound Eros). The rail fuses blow after 20 seconds or so. They work fine on dynamic speakers (classic Allison 1, Infinity Qe) It has been suggested (George Kaye of Moscode / George Kaye Audio Labs as well as others) the amp (which is very wide band) probably needs a RCL network (such as in the older Haflers). Haven't tried that as of yet. Care to comment?


I drive my Acoustat 3/Medallions with a YBA DT Integre and it sounds great. My Acoustats would cause PS2 Blocks in mono to literally catch fire. The low end is so much better with the YBA than with the PS2s.

Were you able to get your TNT 200 repaired? If not, your local TV repair shop ought to be able to do this for you. I suspect your output devices may have gone bad. These are slightly difficult to locate. If your repair person cannot find them, let me know. While you are at it though, you should consider having the bridge rectifiers changed out with Ixys Fred's from Percy Audio. Doing this will reduce the midrange glair of this amp. I know, you were not aware there was a midrange glare. :-) Been there, done that, but once you have the new soft recovery (meaning electroniclly quiet) rectifiers in there, you'll hear the difference.

With the bridge rectifier mods, the TNT 200 can smoke the much more expensive Threshold S/500 amp. I have a Stasis 2 with heavy mods, it sounds better than the stock S/500 as well. I bought a TNT 200 for my youngest son, did the bridge rectifier mods, and now you cannot tell the difference in these 2 amps. The S/500 is no pig, so bettering it is really something IMO.

Best Regards,

Hi Tom,

Zobels are what you are talking about. I ALWAYS use them. Check out:

Download and read the speaker cable article. I do not think this is your problem though, contact Jon Soderberg;

Not only do I think he can help, but he can toss in some Fred soft recovery diodes that will make your amp state of the art in sound. No kidding, the TNT's with soft recover diodes rock. You may want to have him change out the coupling caps with SoniCaps as well. I like Auricaps, but they do not pass bass well, so Jon should use SoniCaps instead.

Best Regards,

Hi Tom,

BTW, if you are thinking, after talking to Jon, that you could buy new for less, trust me, you would have to spend at least 5 times what Jon would charge to get an amp off the shelf that sounds as good as a moded TNT.

Best Regards,

My name is Angelo,and I have a pair of ACOUSTAT
MODEL TWO . I live in Sicily, near Palermo, and I have never had a proper amplifier for my Acoustat, some years ago I buyed one valve amplifier :Art Audio Maestro,
with eight El 34 for channel, but I am not satisfied.
Do you think is yet possible to found a TNT 200 amplifier ?
If is possible I would like to receive a letter, because I can't receive E-mail in my computer(it belongs to a pubbic office). My address is :
Angelo Raspante Via Sac. Sammarco, 31
90011 Bagheria ( Pa) Italy
I Bought one of these delicious monsters used, for $700, maybe 8 or 9 years back. It still works great, but it lets out one hell of a scary WHUMP-PP! when turned on. I always made a ritual of turning on the Acoustat, then the Pre-Amp, then the source, and it never hurt a speaker, but once I turned on the PreAmp first and blew the fuses on some small B&W speakers when I powered up the TNT- I used to always keep extra fuses around after that, but it never caused any damage, except costing me a Dollar or so for a pack of fuses at Radio Shack! I assume the turn-on thump can be fixed... as the amp sounded so great and it never caused any other problems, I was too lazy to bother with the repair shop. Now I'm only selling it because it's just too big, too powerful for the second room system I'm using it for, I plan to scale down and put a vintage receiver in this den/studio, away from the 7-channel A/V system in the front of the house...Hello from John, an Audiogon Newbie!
I own Acoustat 2+2's and have also owned Acoustat Model 2's. Previously I drove them with a McIntosh MC7300 and the sound was top-notch, or so I thought. When I acquired these 2+2’s I got with them a TNT-200 amplifier and a TNP preamp but both had sat unused for nearly 25 years and had hum, hiss, crackling controls, etc. So I set the TNT-200 aside, never giving it much thought since I had my system well sorted with the McIntosh.

I forget why, exactly (probably spurred by reading threads like this one), but I got curious about the TNT-200 a while later and started doing A/B tests vs the McIntosh. It was during a time when my father was in town visiting. Despite the TNT-200’s humming right channel, my father’s immediate reaction was that the TNT-200 sounded noticeably better than the McIntosh. I had been preoccupied with the hum problem but when I forced myself to be more objective it was obvious that he was correct (how could this ugly, buzzing amp sound better than my gorgeous Mac?!). The TNT-200 was revealing more detail and had punchier, lower bass than the McIntosh. The McIntosh sounded somewhat flat and soft-edged in comparison. We A/B'd a few more times just to confirm but it was always the same.

I decided then and there to get the TNT-200 fixed and started making a list of places that still serviced them. This turned out to be a very short list. I contacted the first place but didn’t like what I was hearing, so I continued on and lucked into Ken Ealey of Ken not only repaired my TNT-200’s hum but I was sufficiently impressed by his knowledge and professionalism that I essentially gave him carte blanche to fully refurbish and then modify the amp as he saw fit.

It took several weeks but what I got back was nothing short of amazing. The hum was completely gone, of course. In fact, the amp was dead quiet at rest. Ken had completely rebuilt the amp including replacing the main power supply caps and numerous other parts that had degraded over time. But he had gone far beyond that, to include some circuit modifications and other enhancements that all contribute to making this the best-sounding amplifier I’ve ever heard.

On my better recordings the amount of detail presented is nothing short of astounding. This is particularly apparent on vocals and stringed instruments like acoustic guitar. Bass is deep and tight. Percussion sounds like wood blocks and rim shots are freakishly real. And splash cymbals shimmer on and on in long-lasting sustains.

I’ve had the refurbed/modded TNT-200 in line for about three months now and continue to be impressed by how great it sounds. A few weeks ago I had a visit from an old friend who had moved out of state some ten years ago. He hadn’t listened to his old stereo system in years but the 2+2 obelisks in our living room somehow caught his eye and I proceeded to give a system demo with my Cabasse demo CD.

He was stunned. He commented that he never knew a stereo system could even sound like this, i.e. so real. He could envision the performers out behind the speakers, which didn’t themselves seem to be making any sound at all (and on and on). Just how impressed was he? After never having owned a high-end system he just tracked down and purchased his own set of Acoustat 2+2’s (a pristine set of red Medallions, the lucky bstard!) and has vowed to replicate my modest system in his own house. Now he’s desperately seeking his own TNT-200 which are, unfortunately, seemingly in short supply. Small wonder.
Just sitting here reading these comments on the Acoustat amps because of a conversation I had with some audiophile friends. I have always been a big fan of the 2+2’s with the Medallion Transformers, purchased a new pair with the TNT 200 from Northridge Audio here in California. I must have had a defected amp because it was the dirtiest amp I have ever owned I took it back and had my money returned then went out and bought a Moscode 600. There was no comparison between the Moscode and the TNT.
Anyway just had to get my two cents in.
I have had Acoustat 1100s for about 20 years. I also use B&Ws. No one ever mentions what I consider to be perfect amps for the Acoustats, Audire. I have three Audire Fortes (Two biamping the Acoustats (Peerless woofers) plus one for the subs (Peerless with Thiel crossover)) and two Model 2s. I could not be much happier with them. Compared to my Classe and prior Adcom, NAD, Phase Linear, and Acoustat amps, these almost entry level Audires rock, with much more detail and punch than all but the Classe, which is just weird sounding: I had a bad input cable and was only running one channel, and guess what? The imaging of the Classe was unbelievable. In fact it seemed concocted rather than natural. It is better sounding than all but the Audires and Acoustats in stereo, but smears the sound to expand it for depth and imaging. It does have serious balls, but for its 350 watts per channel, does not sound nearly as focused as the Audires and really does not drive my subs as well as the Audires, even the Model 2s. I have a friend who was a rep for Audire, Threshold, and B&W, and his Class A Audires are even better... much better than the Class A/B Class(e)s. What a stupid pun!
In 1983 I brought home a TNT200 for evaluation. WoW!, I had to have one, but I didn't have $1200. Being a chronic tinkerer, I said maybe I can build one. The amp schematic was in the sales brocure. I disassembled the amp and took photos.
For the next year I acquired all the parts and built the amp. At one point I called Accoustat and talked to the designer Jim Strickland about the three current loop adjustments in the circuit.
Now, 24 years later I am still using my "KransNova" amp driving Magnapan speakers. I still say Wow.

The critical parameters were the capicators in the final stage. Polypropoline, polystyrine, and silver mica caps pass the audio. I spent hours fine tuning those caps to my sonic ears.
Did you know TNT200 was used in some record studios for cutting their masters?