You could try effeciency speakers like Lowther ,AER or Voxativ with 16 ohms impedance,I am using a pair Goodmans 612 fullrange speaker 16 ohms with very good results. |
those comments were in Positive Feedback in the letter's section a few years back.....he and Gizmo were going at it good as i recall.....i have the issue....will dig it out later. |
I don't know whether I should post this or not, but here goes....
I read some comments by David Berning himself once about whether his amp is an OTL. I know, I should have the web address for this, but I can't find it right now. I will look for it. It was either on an old thread (2 years ago?) on Audio Asylum, or on a webpage by Gizmo Rosenberg (not sure of spelling). If I remember right, Berning preferred the term ZH (zero hysterisis) over OTL because of issues like those that have arisen here. I have seen Berning amps referred to as ZOTL's. Again, if I remember right, that phrase was coined by Rosenberg. Now, this was a while ago that I read this, so my memory may be faulty (gets worse every year, sometimes every day I think). When I find the address, I'll post it if anyone's interested. But really, like I said before, call it what you will--the issue is PERFORMANCE. When I get my tax refund, I'm planning on buying a used Joule Electra and having a shootout.
John |
Very good points from all.
However, there are dozens of ZH-270 owners that have had trouble free operation for over 5 years.
With an expected output tube life of 20 years, it's safe to say that one can also expect the same in trouble free years from this unit. |
I like all OTL's and many other amps as well. It just seems to me that as soon as something was said about Berning vs. other OTL's, the fur really flew. Very interesting. Seems to be a very sensitive issue. I hope everyone is enjoying their amps, and I think it is very informative that readers hear the different sides of this issue. I doubt that anyone on either side will be swayed by this discussion, but the process gives opportunity for each to re-think, re-evaluate, and better understand their positions. And good heated discussion is great to "hone" your argument. I am enjoying this thread immensely! |
Well, this "type" has had the Tenor's for nearly a year now without a single problem, I looked right at them and don't "banks" of tubes ( AR REF 300 MKII's come to mind ), and the heat thrown from them is actually less than many other amps I've had, tube or ss. My audio life is quite active (can't say that about other aspects of my life :), the Tenors handle anything I've thrown at em, "look" cool, are as efficient as I need, and although not a physical lightweight, a definite sonic heavyweight. I'm proud they're working great this week ( and all prior) and excited because I'm pretty certain I'll be listening next week and not wasting time wondering if they'll be working. Oh yeah, they also have all the advantages of an OTL. But most importantly, to me, they sound better than any other amp I've had in my system, mystique notwithstanding. |
Now this is the way it SHOULD be, folks really passionate about how they hear reproduced music. btw Twl, did I say thanks to you for starting this thread? |
Well now you've done it. You've analogized amps to exotic cars. I've had it! Having owned a 512 Ferrari, if Ferrari's or for that matter English sports cars ever ran as consistantly excellently as my Tenor 75's, they would have won every race they entered. And by the way, you can't imagine how much money I'm saving on heat this winter.
I don't know a single thing about Berning amps. I do know hollow intellectual arguments and I have spent a lifetime sniffing them out!
If it looks like a duck and quacks like a duck and walks like a duck...
Bill E. |
Oneprof hits the nail on the head, in fact most of you have it right, non of you are wrong, in a way :)
In a perfect world with a perfect speaker, the Berning may not sound any better than any other OTL but who lives in that perfect world, well, some die hard OTL owners do, the ones that Oneprof is talking about, the Berning amps are not for those types, they want to see banks of tubes, they want to have heat, they want to have problems now and then, it's part of the mystique, like owning an English sports car, you know, it works great this week and they have pride in having it work great this week and that little bit of excitement wondering if it will work next week.
Now, if you want to have an active audio life, with an amp that can handle most anything, last like nothing else, efficient like nothing else, runs cool, in a light weight package and gives you all the advantages of OTL, yeah, I thought so, there is noting else like a ZH-270, is there???!!!
Allan |
this is not about words, but about performance. i am another fanatical Tenor owner. so far in my experience, the Tenor easily out-performs ANY other amp in my system (or any system with reasonably OTL friendly speakers).
i would love to hear ANY amp that can out-perform the Tenor in my system and if there is a Berning Owner that lives in the Seattle area or in the Northwest.....come on over and see what happens.....our ears can deciede....and i could give 2 rips whether we call the winner an OTL or not. |
Without trying to be argumentative, I agree that if one wants to call the amp non-OTL because of the "coupling transformer", this gives one an ostensibly good reason. On the other hand if one wants to call it an OTL, one can use my reasoning in the above post. I've already posted my reasons. I think that the main point is that it addresses the inherent difficulties in circlotronic OTL circuits, without resorting to a "conventional"(is that alright?) output transformer for impedance matching. Does so with considerably fewer tubes, with lower heat, lower energy consumption, and excellent reliability. I mean absolutely no disrespect to the Tenor people, Atma-Sphere people, Graaf, or anyone else. So now there is a design that provides(apparently arguably) the benefits of both OTL and traditional output transformer amps with neither of their typical weaknesses(although not perfect). I say that this can only be considered a historic event, much like the circlotron before it. Regardless of how one categorizes it, as several mentioned above, it exists and cannot be ignored. How it will fare in the marketplace is up to the performance level that users feel it posesses, at the various price points. Just like any other product. |
Bill E., I made the same point in my post preceding yours, but since people obviously do care about whether an amp is an OTL or not, let me propose a theory (I should say that I'm an experimental psychologist by training, so explaining why people do things is what I'm supposed to be good at, although most days I wonder about that!:). High-end audio is a social group, a club if you will, and a fairly exclusive one. Within the club, there are 'levels of exclusiveness', kind of like becoming a 32nd degree Mason, or something like that. OTL amps have a certain 'mystique' about them, like they are the 'holy grail' of tube amplification. Being 'recognized' as an OTL confers this mystique upon the amp, and by extension those who own it. OTL owners are serious audiophiles in search of ultimate accuracy in amplifier sound reproduction; everybody else is just playing around.
Now, before anybody who might read this tells me I'm full of crap, I already know that--my wife and kids tell me that all the time. |
So let me understand. The idea of a OTL amp is that there is no transformer between the tubes and the speakers, right? So, here we have a transformer that's not a transformer because we don't want it to be a transformer, so the amp is OTL because we want it to be an OTL and be included in that class of amps.
Other than a desire to argue, what's the point of the debate?
Best wishes,
Bill E.
Owner of Tenor's |
Jtinn, just for the record it is not my goal to invalidate your comments entirely and perhaps my statement of being "quite closed minded" was going a bit far. My intent is not to create personal conflict in this forum, as I do not feel its necessary in order to make a point. Everyone is entitled to their own opinions and interpretation of the design in question. Like many around here often state, "let your own ears decide".
Best Regards,
Chris
|
I say to-MAY-to, you say to-MAH-to. Every time there's a discussion of OTL amps and the Berning comes up, the thread eventually evolves into a debate (to put it politely) over whether the Berning is 'really' an OTL. Who cares? Obviously, some people do, or the issue would never arise. But why SHOULD anybody care? Isn't the issue whether the amplifier, OTL or not, does its job well--namely, accurately amplifying an audio signal? What additional value--financial, 'bragging rights', whatever- would a Berning amp gain from being a 'true' OTL, or lose from NOT being a true 'OTL'? "A rose by any other name would still smell as sweet", said some famous poet.
By the way, I own a Berning 270, and love it with my Merlin Milleniums, whether it's an OTL or not. |
My reading of the schematic on the Berning patent shows no "output transformer." There is a coupling transformer for the RF carrier network that which is what actually performs the impedance matching function. Since this coupling transormer does not perform the function of "output transformer", with the attendant sonic weaknesses(ie phase shift, saturation, and HF rolloff), it cannot correctly be termed as one. So, if you want to nit-pick, here's a nit-pick in return. I will allow that the Berning could not be termed "total transformerless" but OTL does apply for the above stated reasons. The Zero Hysteresis moniker could not be applied if this amp had an output transformer. If you look at the square-wave response on an oscilloscope(as shown in Berning's "white paper") you can easily see the difference. No ouput transformer could behave like this. Perhaps you have been talking to Jennifer Crock, as she has been referred to in an article as saying the Berning is not OTL. I will not speculate on her reasons for saying this, but her misunderstanding of the circuit is not Berning's concern. He makes amps. So, yes it is OTL, no it is not TTL, it is radically creative and brilliant, and it sounds great. No knock on any other great OTLs out there, just my meager expanation on a minor technicality that I wanted to address about the OTL designation. |
Jtinn, your comments are appreciated but in my opinion are quite closed minded about this amplifer design which eliminates the need for an audio output transformer, hence "OTL". Sure, not OTL in the sense of the some 50 year old school of though about OTL tube amps but an OTL design nonetheless.
Please keep in mind this is a new kind of OTL amp design which requires the old school thought of conventional OTL designs to be tossed out entirely and a new sophisticated one to be layed out on the board from scratch.
Anyone want to compare the old school OTL with the new school OTL directly? Please come on by, I'd put this 270 against any other 70W OTL on the market today.
Chris |
Hi Jonathan
You are right, by the truest definition of OTL, the Berning is not. The patent application and schematic is on Berning's website for those interested. It may be a moot point, the proof is in the listening. I am not certain how it would compare head to head with an ideal load next to the top tier OTL's with all other things being equal. I will say that next to the Transcendent 25 watt amp, there really is no contest. My wife, who could care less, noticed it immediately before she even knew I changed anything. The Berning doesn't take a back seat in any performance area. Then again it is more powerful and this can certainly come into play in the equation. The big difference is the clarity at all frequencies of the Berning over the Transcendent. There is also a better sense of space and definition. Bass performance is in a word, incredible. Not only control but placement in the recording space, much better than the Transcendent. This isn't really a fair comparison since the Transcendent is less than half the price. But to these ears the Berning beats the hell out of any transformer coupled amp I've heard. The Transcendent does too, within its power limitations. It is just that these designs are faster, more resolving and natural sounding.
There are varying opinions about the Berning on some stats, especially at the frequency extremes. This in comparison with other OTL's. With the benign load of Merlin VSM-M's the performance is stellar.
I'll just go on believing that it doesn't get too much better than this. Ignorance truly can be bliss especially at this level of performance. |
Thorty40: This was made clear back when they were introduced. While it is a brilliant design, it is not an OTL. It is a transformer based amplifier that is biased by a high speed oscillator to reduce hysteresis effect of the transformer.
An output transformerless amplifier does not have a transformer between the tubes and the speakers. The David Berning amplifier has one after the tubes. Ask to see the schematics published in the patent application. In your own statement, you aver:
"Ok, the RF re-mapping occurs through the use of a tiny RF transformer at a carrier freq. of 250kHz."
The transformer you speaker of, is in between the tubes and the speaker leads. Hence, it is in no way an OTL.
To reiterate, it is a brilliant design and while having the ability to drive impedance challenged speakers, if put head to head with a proper OTL on a stable load, you might be surprised at which one sounds better. Again, I want to make it clear that if I had a limited budget and a tough load to drive, I would give the Berning amps real consideration. |
jtinn,
Apparently I ruffled a feather or two when I stated my "opinion" that I preferred the Berning to the Tenor. I do agree that the systems were different. I cannot imagine, however, that manufacturers mate equipment at these shows with speakers and associated equipment that they did not feel brought out the better attributes of their products. That being said, I like most people in this hobby, am not afforded the opportunity to take home any and every product for evaluation on a master reference system. This being the case, I choose to participate in attending shows and frequenting audio shops so I can hear as many products as I can and gather as many "opinions" on equipment as possible. I do this with a clear concious in an effort to make an educated and yes, subjective decision on what products I like and dislike. Because as we all know in this hobby, it all comes down to what you like and nobody else.
Kris |
Mejames, I would think that any good speaker to your liking would work well with the zh270. Bear in mind that it is 70 watts per channel, so the selection should include that criteria. As you may know already, I am quite opinionated in my speaker recommendations. For HT however, I am less stringent in my opinions. Generally, I would say pick a speaker that would fit your liking for both categories and use them for your mains/fronts for both audio and HT. Since I don't know your particular taste or budget, it's hard for me to recommend a particular speaker, but a full range dynamic type would fit the bill for both applications. An 8ohm load sounds better than 4 on the Berning OTLs. So I would go with 8ohm. Probably an efficiency level of about 92-95 db would give plenty of room for the dynamics of HT. |
could somebody recommend a good home Theatre speaker for use with the Berning 270 amplifier? |
Mes, your point was misconstrued by Tubegroover, not me. I understood your point perfectly and thanks for your comments on my post and on the thread. |
twl, you're right, you didn't get the point. Or the relevence. BTW, classy reply to jtinn. |
Jtinn, thank you for your comments. As I mentioned in my last post I apologized for any offense that may have been taken, and said that I am not accusing you directly of doing the bad stuff that is common in the industry, as I have no basis for such. Just for the record, I am not the person that made the comments comparing the amps in different systems.That was Kris, not me. I just made a conjecture on what I thought would be the result of the comparison. From what others have said here on the forum, you are a good guy and have been helpful to others, so I defer my pointed remarks. However, the industry in general is most deserving of those pointed remarks, and I think that it has injured the hobby with its much less-than-pure approach towards its customers. I am now sorry that I included you in that group, in light of what I have now learned. Enjoy those Tenors and perhaps, one day, I'll even have the chance to try some in my system. Happy listening! |
Mes, I highly doubt that anyone is going to "take a bath" on a 4.5k amp when upgrading to one 4 times the price. I don't see the relevance of your post nor understand your point. Used Bernings don't seem to hang around on the market long. Berning's reputation seems to have been built on word of mouth more than marketing hype. Maybe another reason for the relative obscurity of his products to most audiophiles. His approach appears more 'take it or leave it". He doesn't need to push his products and if you weren't aware, has been around much longer than most of the other well known hi-end manufacturers with very few exceptions. The reason? low overhead and product acceptance. The guy hand makes each amp in his home. Now that's what I call sticking to basics. |
If I read this correctly, it seems to me that twl's criticisms of certain products being "flavors of the month" and individuals possibly "taking a bath" on resale of said products, could be accurately applied to srause's experience with the Berning, no? Hmmmm..... |
Twl: The comment you made has no foundation on fact. You heard two totally different systems with all different components and made a statement about the amplifiers. It is improper and highly incorrect (maybe subjective). I do not need to recuse myself because I do not feel I am improperly participating.
I agree with your concerns about the audio industry and feel as do you. I do not need to sell anything or hype anything just for the sake of making a buck. I like music and what gets me closer to the live experience. I enjoy helping others in that search as well. If it is profitable, at times, great, if not, great too. I think most people I deal with respect the fact that I have a decent ear and speak of what I know and have experienced, not what makes me money.
You seem to be a straight shooter and talk passionately. I respect that and look forward to your future posts.
Best Regards,
Jonathan |
Just for the record Tubegroover, I haven't worked in audio for almost 10 years now. I feel bad about hammering Jtinn like I did, but when you are an audiophile and you hear stuff like I heard at trade shows, it really scorches your hide. They want to herd us around like livestock to the slaughter with their hype and magazine reviews. Now, I know there are alot of great products out there and I am not going to say that 1 product is best for everyone, and am sure that you or Jtinn would feel similarly. I am just very sensitive about the revolving door of product hype based on the need to sell. Sorry If I offended anyone(Jtinn). I have no knowledge of him personally doing any of the negative things I mentioned above. |
Twl In defense of Jtinn I would like to say this, he has always let it be know he is a dealer in each thread he is involved in where he offers an opinion or rave. I certainly sense his enthusiasm for the Tenor and have come to highly respect his input. The Tenor has really gotten high praise from every corner. Then again I would expect nothing less based on its price. If it turns out to be a mirage, the company won't last. I would love to hear it in my system but I could never justify to myself (or wife) spending that much money on an amplifier.
I am probably not as critical of this as you might be since you are an insider and better know than I how it works. You make some interesting points. I on the other hand have never been involved in the audio industry. There is not one individual that could ever pursuade me that one thing is better than another. Only my ears will do that. One of the most important things I always try to convey to anyone seeking my opinion is that yes, you may respect it but to ALWAYS trust your own ears first. Opinions from trusted peers just help narrow down the choices.
I also feel it is useless to compare two completely different and unfamiliar systems and try to attribute the sound of one over the other to a particular component, there are too many variables. The big plus for the Berning amp over the others is not whether it is the absolute "best" but all the pluses it offers over other OTL's including cost. My assessment using that criteria is, nothing I'm aware of comes close. Others may look at that comment as a compromise when to them only the "best" counts regardless of anything else. Unfortunately best often times is associated to price and it is not always true.
And thanks Twl for starting the thread. I hope it has the benefit of opening the eyes and ears of those that are looking for something they haven't yet heard that resides only in OTL designs. |
Jtinn, BTW, Kris is entitled to his opinion, just as you are. Just as I am. Please do not feel threatened if another amp line surpasses your favorite. It happens to your customers all the time, when you have something new and great to sell them. Probably doesn't bother you a bit that they are going to take a bath on the money they lose selling their old gear and paying you profit on the flavor of the month. After all, how else would audio businesses continue to make money. I've worked in several audio emporiums and know people that worked in others, been to CES, and other shows and rubbed elbows. I know the comments that are made between dealers and mfrs. It's all about churning. Just like the stock brokers: buy, sell, buy, sell. How many "turns" will you get on a particular product in a year, is the major concern. And how much margin. Hype the latest hot item, and next month hype the next. If a customer's system gets superceded by a better(newer) product, well "that's just the electronics biz." But if you've got $350k tied up in the minimum stocking order to retain a dealership, then you better believe that amp is going to be the "best you ever heard".I hate to be this hard on you, but you threw down the gauntlet and now I'm telling you that your opinion cannot be considered objective because you have financial interest in certain products selling well. Conflict of interest, I believe, is the term. You should recuse yourself from this discussion due to conflict of interest. |
Srouse, I haven't heard the Exemplar amp. Did you hear a 2A3 or a 300B? Checked into it at the Bottlehead site. It seems that he(John) has gotten some input from the Bottlehead people on his amps. Bet they sound great.90kHz bandwidth, must be a helluva output transformer! |
I had the Berning amp here for six months and then sold it after hearing the Tenors and amps from Exemplar Audio. Both were superior in every audiophile parameter you can think of on Merlins VSMs and Beauhorn Virtuosos |
Kenl,
I have a pair of Avantegarde Duos. I found that I needed the integrated subwoofer to really enjoy all types of music. I didn't like the single driver(full range) speakers--no frequency extremes tho they do midrange very well. As to the amps, I did compare the two. The 270 sounded great but in comparison to the 811 was more OTL-like e.g. faster and slightly harder sounding. The 811 had slightly more midrange bloom but most importantly for me was that I started listening to the music and forgetting about audiophile sonic attributes like soundstaging,speed,
detail,etc. With the 811 the speakers completely disappeared. Hope this helps. |
Jayarr,
Which horn speakers did you settle on? I own a Berning 270 and am myself interested in horns. Did you try the 270 with the horns before selling it? How did it sound?
Thanks. |
I also own a Berning amp. I used to be a solid state kind of guy until having an epiphany regarding OTL tube amps. I listened to an Atmosphere amp and was blown away. I started researching OTL amps and became interested in Berning amps because of their novel technology. After listening to ZH270, I bought it. I recently changed to horn speakers and didn't need the power of the 270. So I sold it and purchased the 811 ZOTL. It has all the attributes of an OTL amp; clarity,speed,soundstaging, along with the SET midrange magic. I prefered the sound of the 811 over the 270. I think it has something to do with it being Class A with no negative feedback and single ended (unlike the 270). |
I agree, OTL is where its at.I hooked up my Futterman design NY labs amps to a pair of 15" Tannoy dual concentrics I picked up at a garage sale two years ago, and could not beleive what I heard, amazing natural music, I relax when I listen to MUSIC, not HI-FI.I put away a pair of Quad 63 US Monitors,and a pair of Magneplanar Tympanis and just listen to a pair of 40 year old speakers. By the way the Tannoy speakers are 15 ohm.There is some serious synergy between amp and speakers. I would love to hear from others using same/similar gear. Tubegroover is right, OTL is where its at. |
Cool post, Tubegroover. All modern OTLs take the music one step closer to the truth. One comment I would make about the load stability is that the large number of tubes is also an attempt to lower the output impedance of the amp, not just current drive. The output impedance of the Berning amps is 2ohms or less, depending on model. And this is the case with relatively few tubes. This is the real breakthrough in the design in that the RF carrier system replaces the output transformer's task with a much higher turns ratio than possible with iron. Thus allowing fewer tubes, better efficiency, less heat, and a lower output impedance than previous OTL designs. And, it's not really in the signal path, just carrying it. Grid drive. Not cathode follower or circlotron. All new. With previous OTLs, damping factor was a problem because the amps output impedance was high enough to sometimes be above the load impedance and damping was seriously compromised.With a 2ohm output impedance the Berning design breaks new ground with respect to damping and does so with few tubes. In fact, in my MicroZ OTL, the output tubes are 6sn7's. Normally a preamp tube, and a great one. Tube heads out there know that preamp tubes are generally much more linear than power tubes. This is really the first time a linear tube such as the 6sn7 is actually driving a speaker directly. It is amazing. And very short signal path, too. Detail is dramatic. Midrange is liquid, and bass is fast and solid. The sound is balanced from top to bottom. If you just take the sound, not the power level, it is the equal or better of anything there is. I can't believe that I could afford such a thing, but here it sits - all 4 pounds of it! Must be a dream. David Berning is a genius to have thought up this level of tube "groovosity."(As Harvey aka Dr Gizmo, called it) |
Twl I am also a Transcendent folk, still have it. A great little 25 watt amp it is. This is the one that brought me to the realization of what OTL amps are all about. I doubt that you can do better at the price and power rating.
Regardless of which of the OTL amps that are choosen for a given application and load the one indisputable fact is that these amps as a group are uniquely special. After all, this isn't a p...ing contest, is it? I have not had the priviledge of hearing the Joules, Graff or Tenor but I'm sure they have their virtues and that each might be picked over the other in a given application.
My problem with Siddh's choice is that I can't live in Florida with an increase of 8-10 degrees in my room, the plants would wilt and so would I. I'm sure I could live with its sonics which by all accounts is among the best. But 220 OTL watts, must put out 1200-1500 watts at idle. I guess I could settle for the M-60's, still a lot of heat. This is why I went with the Transcendent originally but ultimately it didn't have quite enough headroom with certain music.
The Atmaspheres, Joules and Tenors may be better on an absolute level than the Berning with a given speaker system. The Berning would be a better choice for me with my speakers and probably would be a better all around choice for a lot more audiophiles. What other tube amp increases power ala ss into low impedance loads? Transformers saturate and compromise the bass and high frequency performance and OTL's start doing crazy things to the dynamics of the music and become unstable into such loads. Well you just add more tubes to up the current. Sounds like a great choice if you live in a cool climate or have a dedicated venting system for the amps. This is the whole point of Bernings' design. |
C'mon, where are the Graaf and Croft people? And how about the Transcendance folks? |
Let me join Siddh in praise of Atma-Sphere OTL's, neglected in most of this thread. I'm using a pair of M60 II.2's with half their output tubes removed, with Quad ESL 63's, whose impedance drops as low as 4 ohms though is mostly closer to 7. The point being, that's high enough. Not the 16 ohms some OTL's may need. Reliability is fine too. I did an odd experiment, using a Pass Aleph 3 as a monoblock (input and output both paralleled) for one speaker and a M60 II.2 for the other. There was nothing clearly wrong with the Aleph 3 sound, as I switched back and forth on good mono material, but I preferred the warmth of the M60 II.2 sound every time. I wasn't giving up anything, detail, transparency, certainly not palpability if we may speak of that, as far as I could tell. That made me decide I was a tube person for life. |
The Berning ZH-270 is just a marvelous amplifier that can drive many speakers with ease. This amp is very musical, quiet, and has lots of drive! The ZH-270 is revolutionary and best described by Thorty40 and Kenl. I love my ZH-270 and would only consider replacing my present system with a Seigfried or Art Audio amp with a high efficiency horn speaker. |
Thanks, Thorty40, very cool pix. |
Twl, well put, your comments hit the nail right on the head. Why do so many seem resistant to the thought of a more evolved OTL design? That is my question.
Try this -
www.condor-connection.org/slog/
Then goto SLOG on line, view archives, on line archive 1, scroll to roughly the middle of the posts and find "here's the correct image" by Brian Walsh 10/24/01 and click on the thread.
That will take you to the picture.
Chris
|
Thorty 40, I couldn't pull up your URL with my search engine. Would love to see that design. If you could find another way for us to see it, it would be much appreciated. |
A little surprised not to have noticed Atma-Spheres on this thread. Compared to the other amps I have owned, tube or solid-state, the MA-2's have outperformed all in nearly every category. Bottom slam, midrange transparency, and extension up top...all beautiful and musical. This, of course, is with the system I have assembled. Avalon Eidelon, Jadis preamp, CEC/ Audio Note digital, Clearaudio TT, FIM cable. I have enjoyed many systems, but none for as long or as consistently as that which I have forementioned.
Reliability has so far been a non-issue. The 220 watts/ channel offers more than enough juice. The heat generated is something else. My room must increase a good 8-10 degrees. Great in winter, but summer....
I have not compared to other OTL's but reports on performance carries similar subjective remarks. A cleansing in clarity, bringing the listening experience closer to the recording venue. Must be heard in a well designed system. |
Jtinn, my recommendation to you as a dealer would be to audition the Berning line in your system. I believe that if you do this, you will pick up that line as your new reference standard. I am sure the Tenors are exquisite amplifiers that anyone would be proud to own,with great sound and beautiful build quality. I do not intend to knock them and perhaps went overboard with my "flat as a pancake" statement. However, as Tubegroover stated, Berning has established a new path for OTL that creates a new standard in the OTL field. The typical circlotron OTL circuit topology has been superceded. The inherent circlotron weaknesses have been replaced with a superior design. And, of course, the previous cathode follower and Futterman designs had been surpassed years before by Ralph Karsten and his Atma-sphere circlotron design. I love OTLs and all of the great amps out there that use OTL design. I just have to recognize that there is now a superior design that will take us further toward OTL perfection, and that design is the Berning Zero-Hysteresis OTL amplifier. Cheers. |
http://www.condor-connection.org/slog/bbs/messages/422.html
This is an link to an image of a cutting edge, state of the art designed OTL amplifer made by David Berning based on ZH technology used on his current product line up.
As you can see by the internal layout, this is a radical departure from the conventional OTL technology based on Futterman principals some 50 years ago.
This mono block weighs 8 or 9 pounds and puts out 120W into 8 ohms and INCREASES output power into lower impedences.
Just for a minute, think of all the limitations and drawbacks associated with the current OTL amplifiers. Now think about one without these limitations, not possible? Incorrect, it is possible and happening right now. |
"The Tenors can handle impedence swings as well as any OTL."
Not true actually, the Berning OTL's INCREASE output power into lower impedences. The Tenors cannot do this simply due to the nature of their design. This does not mean they are not great sounding amplifers, it just means they will have to struggle more with more difficult loads than a single ZH270. Lets quickly look at a couple specifications -
Tenor 75wi (monos) - @ 4, 6, 8 ohm - 55, 75, 75W respectively.
Power consumption - 730W (not indicated if this is idle or max.)
Berning 270 (stereo per channel) @ 8 ohm - 70W (84W output at onset of clipping), 4 ohm - 110W at onset of clippin.
Power consumption - 100W @ idle, 300W max.
I doubt the Tenors (or any other OTL) withstand less than 2 ohms or less for very long without losing steam, they were not designed to drive those difficult impedences with any consistancy. A ZH270 I know for a fact will tolerate quite low impedences for extended periods AND can provide much higher ouput power into lower impedences because of its unique ability to match impedence.
For example -
I personally heard the ZH270 drive a pair of Magnepan 3.6QR's LOUD with lots of drive tolerating some huge dynamic swings while playing some crazy techno music. For the kind of headroom we had one would think we were using some big solid state bruiser, but we weren't. We were using a single ZH270 with the difficult to drive Maggies.
Any 70W amp has its limits, true but we are discussing the subject of OTL amps specifically and I would welcome a friendly comparison with the Berning ZH270 and a Tenor Classic 75wi. I am confident a single 270 would do more than hold its own with the Tenors, especially with difficult to drive speakers like the Magnepans and/or ESL's for that matter.
Chris
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Twl-When you think of SETs you think of the late Gizmo Harvey Rosenberg of NYAL's fame. He went absolutely bonkers over the Seigfried and the zero hysterisis technology in general. The ultimate realization of tube technology today must include the Siegfried with either the 300b or 811 triode. Imagine a low powered SET that isn't limited to that magical midrange but expands its performance into the high and low frequencies as well. Regulated switching power supply and an OTL output stage, dead quiet, auto biasing, reliable, low heat and elimination of transformer related distortions. Where do you go from there? I guess it can be refined but in reality Berning has established a new path and there seems to be a hush over it in the audio community. I haven't heard this amp yet but can only guess that it sets new benchmarks for SET design and may be near the pinnacle of reproduced audio with the right speakers for those looking at this approach. There is much to be said for low power and highly efficient speakers. The zh270 itself is so incredible that you really have to wonder about the advanced level of design and engineering in these special products. I haven't stopped wondering since I got mine over 2 months ago. |
