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In Reply to: Re: Joule... posted by ABhagan on October 18, 2004 at 20:51:03:
that the Berning amp uses a "Impedance Converter" (as described in Hansens article that you linked to) to couple the "output" tubes (or the output of the amp if you will) to the speaker/load. Also, I think we can agree that . . . while the output tubes of the Berning amplifer are coupled to the speaker through a Impedance Convertor, "traditional" OTLs designs use no such device and the output tubes are directly or capacitively coupled to the speaker.
Hmmm now maybe I should tell Jud to call his amps "direct output coupled OTLs" instead of just "OTLs"... :-) :-) :-)
Rich, let me get this right, a amp can have a capacitive filtered coupled output and still be called a OTL but a amp that is not capacitive or transformer coupled and operates a Impedance converter, out of the signal path at 250kH is not a OTL?
It seems somebody is making up some funny rules that are not fair or right for the consumer.
Yes, or course traditional OTL's do not use RF impedance converters, traditional OTL amps were designed long before modern power conversion technology, maybe the best way to describe it all is in two categories.
Traditional OTL (TOTL)
Modern OTL (MOTL)
To say the Berning design is not a OTL is misleading, it's just not traditional OTL.
As for this statement
"while the output tubes of the Berning amplfier are coupled to the speaker through a Impedance Converter".
The answer is, not in the signal path, nor at audio frequencies, so why is it relevant, when there are OTL makers with a capacitive coupled design and that's not?
I think it is equally as misleading to call the Berning amp an OTL as it is to say that it is not an OTL. It is an Unconventionally Coupled Output, the one and only "UCO". As for your beef re coupling caps, some folks do distinguish cap-coupled amps from direct-coupled ones and refer to a direct-coupled OTL as an "OCL (Output Capacitor-Less) OTL". But my point is, who cares? The Berning is a brilliant original creative design that sounds great, and I for one would welcome ZOTL owners to this website. OTLs and their owners have been slandered for decades, so we cannot afford to be undemocratic now that we have our own website.
Thank you so much for having an open mind.
It's not so much for the recognition of it being a OTL amp, as for it not being categorized into anything else which it is not, that stems our obstinacy.
If the Berning owners can freely communicate their interested here without discourse, then that is all we can ask.
I agree. Who really cares. I never bought into the hype of "is it or isn't it" really an OTL. As a former ZH270 owner for three years, I found it to be one damn fine sounding amp. If I could have swung the bucks to keep it and the JE VZN, I would have.
For me, it's a large tent and there is plenty of room for ZOTL folk IMHO.
"Rich, let me get this right, a amp can have a capacitive filtered coupled output and still be called a OTL but a amp that is not capacitive or transformer coupled and operates a Impedance converter, out of the signal path at 250kH is not a OTL?
A cap on the output of an simple amplifer is used to block DC from getting to the speaker... it provides no other function. From an audio signal point of view... the speaker sees the output impedance of the active device (tube or transistor) and the amplifing device see the impedance of the speaker. The capacitor in this case is not an impedance matching or "transforming" device. Inductors are often used on the output of power amplifers (tube and solid state) in such a manner to block high frequency (ultrasonic) info from boucing around through amp (generally through the feedback loop) and driving the amp into oscilation. Again, another reactive device (i.e a inductor or capacitor) that does not effect how the speaker or the amplifing device see each other.
Again, a output transformer at its core purpose in a audio amplifier is a impedance matching device (in the case of tube amplifer - take high voltage low current tube power and transform it to low voltage high current power that is best suited to drive the low impedance speaker load). Look at the Hansen article you pointed me to ... figure 10. As you can see there is something there between the amplifing device and the load.... it is even defined as a impedance matching apparatus in David' patent. The only direct path between the ouput device here and the speaker is a common ground. If there was nothing but a peice of wire a one or two passive parts between the tube and the load, why would there be something worth patenting here????
I'm getting tired and rambling... Alan it is hard for me get into this becuase I get so easily fustrated. Our audio world is not perfect... and full a various terms and terminologies which have certain implied meanings and ond connatations... single ended, push-pull, SE, SET, OTL, etc. If an OTL tube amp is a Orange, and a conventional hunk of iron output tranformer coupled tube amp is an Grapefruit, then the Berning amp is Tangerine. While it may be a relative of both fruits, it should certainly not be confused as one of the other fruits.
OK... now that I've really gone off the deep... Icall it quits for today.
Rich, I am really enjoying this debate, I hope it's not wearing you down.
It is obvious that the ZH-270 is not a typical OTL, but just by the fact that it does not have a output transformer, simply makes it a OTL by default, now what it is other than that should be another debate.
The reason there is something worth patenting here is that there are different ways of doing the same thing or getting the same results, Dave is able to get the same results of a conventional OTL while matching speaker impedances and a whole lot of other benefits, simply matching speaker impedance is not patentable, doing it in a OTL fashion is.
You make it sound like this design is a compromise, while in fact it's a true innovation in amplifier design, Hansen even made that comment.
Yes, in the Audio industry today, there are many Mars dust, voodoo spells, nonmetallic metal drawn from the breath of god, invisible sound force fields type products out there and it's getting damn hard to discriminate between magic and science.
Let me spell it out as I see it, because there is so much bunk out there and the Berning is so complicated and way over the wall in design, it seems more comfortable for the Status quo to put it into the "magic" realm to try and discredit it.
In fact they should really be glad a product like this came along, it shows that new technology can be put to a sound design like OTL's, bringing the OTL into the future, giving it life and excitement, the ZH-270 does not compete with the VZN-100's or the MA-2 but does compete with Solid State amps, someone buying a ZH-270 becomes a future potential buyer of a VZN-100 or a MA-2.
The ZH-270 is a easy amp to transcend the SS to tube move, it's light, cool and reliable, once the consumer has made the move to OTL in this manner, it's hard to move anywhere else but up the chain, and at $4995.00, there are plenty of options to move up to and at this time non being a Berning, a VZN-100 and MA-2 heaven.
David Berning Co
You already know where I stand on this (non)issue. I always wondered instead why Berning turned away from the 6SN7 as an input tube, which he did use in his earlier designs. IMO the 6SN7 supplies a certain magic that is lacking in the 12A*7 series or in the 6DJ8 and its congeners. I would love to hear a ZH270 with 6SN7s on the input side.
In fact I have admired design for many years ever since it was first written about in Positve Feedback Magazine several years ago and even more so after I had the chance to hear it first hand back in 1998. You wouldn't find a picture of David's Sigfreid SV-811 (see the link below) amp on my website if I didn't think it was something special. As an electrical engineer though, I have a tough time calling something that does not to my experience and education fit the word OTL. When I read through the technical articles, this little voice in the back of my head screams.. "Holy crap!!! He has built the ideal output tranformer! A device that does many of the things that a theoretical ideal output transformer does (I'm speaking in engineering terms here... an theoretical ideal output transformer has no hysteresis, inductance, capacitance etc that limits its bandwidth or cuases any other problems)... and becuase of that, very linear push pull and single ended tubes amp can be made."
BTW, I very much agree that the Berning design topology is a great high end step into the world of tube amps for those who have stuck with high end solid state amps over the years. In many ways it is the ultimate no muss, no fuss tube amp. If I do have criticisms, it has more to do with more pratical things (like the crowded rear panel layout of the ZH-270, the lack of a single input no volume control version, and I would like less gain) which I think would make the amp more universally appealing (though given the backorder situation, I doubt these are a concern! :-) )
Retailer & Audio Asylum Industry Liaison
"Holy crap!!! He has built the ideal output tranformer.
I know, it's because I think it's portrayed or described in a simplistic manner, as I said before, the converter is really only part of a number of transformers that make up a circuit, an is no way configured or coupled like a output transformer to the circuit and the converter operates at a fixed frequency of 250Kh, and cannot operate at audio frequencies, there is just no way of mistaking this thing for a output transformer.
It's a perfect something but not a output transformer :)
Yeah, you missed one, it's also very plain looking ( that's polite English for kinda ugly )
This is not an amp someone buys on impulse :)
Alan, you are looking too closely or you think I am focusing in on the inner details of the impedance converter circuit. Think about what the amp does at a higher level.... what does the speaker see??? what does the push pull amplifer section of the amp see??
Understanding the details of the circuit is one thing... but you are missing conceptually what the very clever David Berning impedance convertor circuit does. While is does not use conventional output transformer technology (i.e a core of magenetic material wraped with coils, with a primary and secondary winding that has a speaker connected on one end and output tubes on the other side), it essentially emulates what a conventional output transformer does, but in a *much* better manner.
A OTL (in the spirit of the term that is most well understood by audio geeks) has no such impedance converting device between the output tubes and the speakers... i.e. what are more specifically called direct coupled OTLs... the tubes directly drive the load. Thing is though, you will very rarely ever see a audiophile use the term direct coupled OTL becuase is is essentailly assumed by defiention that what he/she means. I think calling other types of amplifer designs OTLs does a diservice to the audiophile public becuase they MAY very well think they are getting/seeing/reading about a direct coupled OTL when they are not.
"what does the speaker see??? what does the push pull amplifer section of the amp see?? "
the speaker “sees” the tube transfer characteristics and the tubes “see” the speaker’s dynamic characteristics.
Just at it would in any direct coupled OTL.
No amount of emulation of any output transformer can do that :)
"I think calling other types of amplifer designs OTLs does a diservice to the audiophile public becuase they MAY very well think they are getting/seeing/reading about a direct coupled OTL when they are not."
Are all production cars internal combustion, with either a automatic or manual transmission, are all TV's vacuum tube, you need to be blasted into space by big rockets? At one time or another, the answers to all these questions would have been yes but not anymore.
Electric powered cars are not cars?
Plasma TV's are not TV's
Flying a plane into space is not space travel?
By not letting the audiophile public know that they have choices over what was conventional with the same results, is really the disservice.
and he is checking out a SUV..,
Salesman comes up and say "Can I help you"
Customer says, "Yeah, I'm looking to ge one of these SUVs. This one here has a gas engine in it right? I'm not looking for a deisel."
Saleman says "Yep, got a V6 gas engine in there."
The customer thinks, "great < I got a fiar deal here, lets get it!, and makes the deal for the truck there on the lot. He come back next monday, picks up the SUV and drives her home. Being a curious guy (thinks he knows a thing or two about cars & thier design), the guy pops the hood and takes a look at the engine... he aslo takes a look undearneath the car and grumbles out loud "What the *****?" Turns out the customer's new SUV is a hybird Gas electric vehicle.... you don't have to plug in, and runs and drives just like a regular gas SUV... heck, gets even better gas milage.. "its better" the saleman and company says to the upset customer "look how more efficent it... the way the motors and such work you save on brakes, etc etc."... "No matter", the customer says, "you folks decived me becuase you didn't tell me upfront that I wasn't getting the old fashioned gasoline drivetrain that I originally asked for!"
Moral of the story, while the gas -electric hybrid vehicle may drive, ride, brake, handle just like a old fashioned gasoline engine vehicle, it does not make it one.
Retailer & Audio Asylum Industry Liaison
Okay, but the customer could just as easily have gone home and popped the bonnet and said %&^^ing shit, look at this amazing technology, it gets better gas mileage, it's better for the environment, it's faster than the regular gas only model, requires less maintenance, calls the salesman and thanks him and his company for having such a SUV, "it's certainly a great vehicle, you should tell more people about it" :)
We should have a vote on which scenario is most likely :)
Man, where would the rest of the world be if it was not for newer ways of doing things, still be watching black and white TV's, driving undependable gas guzzlers?
"Okay, but the customer could just as easily have gone home and popped the bonnet and said %&^^ing shit, look at this amazing technology, it gets better gas mileage, it's better for the environment, it's faster than the regular gas only model, requires less maintenance, calls the salesman and thanks him and his company for having such a SUV, "it's certainly a great vehicle, you should tell more people about it" :)"
You are of course, correct and indirectly make my point. Since this is different tehcnology, call it and market it as something different.... the interaction could have been:
Customer: "So is this one of those newfangled gasoline electric hybrids???"
Salesman: Yep! The best that technology currenty has to offer... the performance like that of a gasoline engine with better enconomy and better for the environment... you see the gas engine provides extra power for the batteries and the electric drive motors when needed... works seemlessly and drives and rides like a regular SUV. Now if you want, we also have the old fashioned gasoline engine driven SUVs as well..."
So now the customer can make an informed desicsion... maybe he is an old fashioned guy, likes to work on his own cars and just wants an old fashioned gasoline engine SUV. OR, maybe he is a guy excited by this new technology and a SUV that gives him the utlility of such a vehicle with better economy/efficency.
Retailer & Audio Asylum Industry Liaison
Oh, don't get us wrong, we know Output transformer less is the least of what ZH technology is, our starting point.
Yes, you are kind of right, but I don't see a New amp technology forum and it would be kind of boring for the Berning guys anyway :)!
The real big problem is the CIRCUS that high end audio has become, a audiophile cannot tell between magic and science anymore, fundamentally what is correct, is getting grayer and grayer.
It is now very difficult to differentiate yourself with a break true technology to some voodoo spell hybrid lie and because people cannot understand the ZH technology, it's just easy for us to say OTL.
I can go on about this industry but I a sure you know what I mean.
Oh gees and I was just getting started :) Na, it's not advertising, I would not have said a word if it was not for the it's not a OTL thing :)
It's great to have you on board here. It would be good to see Tom Lyons over here as well. Give him an invite if you happen to talk with him.
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