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Anyone has tried these amps on Avantgarde DUO? What do you think?Thanks
Follow Ups:
I have the Duos and the Seigfried 811-10. I love the combination. Plenty of power, dynamics, transparency, resolution, natural tone and timbre. This is not a euphonic sounding SET amp in spite of it's Class A directly-heated triode heritage. Very different than say a Audio Note SET amp which has a more midrange emphasized sound(neither better or worse just different). The 300B version is slightly warmer. I don't know why Berning stopped producing the Siegfried since 300B and 811-10(Parts Express-Svetlana) tubes are still readily available. I've heard the Atmosphere MA60,with Merlin speakers tho not with Duos, and was very impressed. I agree that 60wts/ch would be overkill and wasteful(way too much heat production). The info about the Berning OTL having a transistor based output is just plain wrong. Check out the Berning website and also check out previous threads regarding this subject. BTW, I also owned a Berning 270 and briefly compared it to the Seigfried on the Duos and liked the Seigfried better. The 270 was more etched,slightly artificial,less intimate,tho with slightly better bass than the Seigfried. Hope this helps.
I am presently using the M60-2.2's on the Duos with reduced gain. V2 in the gain stage has been by-passed. The amps are as quiet as a field mouse with the MP-3 pre-amp. The sound is wonderful, compelling, and addictive. As soon as the amps & pre.-amp warm up, you're glued to your seat. You put on an album, cd, you forget your responsibilities in life, sit, listen & become part of the recording.
I've tried a few other amps & I still come back to the M60's. There is no amp that I tried in my system or heard with any Advantgarde that is as good. (My Humble Opinion) I simply love Atma-Sphere & now I'm falling in love with Avantgarde.
Correct me if mistaken, but isn't the Berning ZH270 (Seigfried too) using the tube merely as a device to obtain a voltage amplification analog signal which in turn is used to drive a sophisticated active voltage to current converter employing mosfets and other active devices? In other words the behavior of the tube becomes the signal analog to influence the active voltage to current converter which is entirely solid state. To call Berning's amplifiers OTL is a misnomer. True they do not use transformers in the conventional way to change voltage swing in output tubes which would like to see a very high impedance as load, but calling them OTL is wrong. To do so one would then have to call any amplifier that used tubes on the front end and transistors on the output an OTL, and this is plainly wrong. OTL refers to a tube amplifier that does not use an output transformer to couple the amplifier to the load. Also, it should not use active transistor, fet, mosfet, or other active solid state devices to couple the tube to the load. I think this fuzzy OTL thinking came about as a result of misinformed reviewers who wrote out of ignorance or carelessness. Unfortuneately there is a lot of tripe that gets put into print at the hands of reviewers.
Well, this is how DB apparently described its operation at one point:The ZOTL falls into a generic class of amplifier described by the acronym OTL both technically and in spirit. The power conversion transformers called out by the patent cannot and do not operate at audio frequencies. The semiconductor devices called out by the patent drive these transformers at a fixed 250 kHz and do not operate at audio frequencies or as amplifiers. The patented ZOTL circuit is a two-way coupling circuit that performs impedance matching like an audio output transformer, but does not have any of the limitations and distortions imposed by audio output transformers. This circuit is in no way a buffer, such as a transistor output stage in a hybrid tube-transistor amplifier. There is no power gain, and more importantly, the speaker “sees” the tube transfer characteristics and the tubes “see” the speaker’s dynamic characteristics.
Based on that, I could call his creations, not OTLs, but NOT's for 'Nonaudio Output Transformer Amplifiers'. There's still an output impedance/voltage transformation based on a transformer ratio, unlike in OTLs but as in conventional tubed power amps; however its achieved with high frequency solid state switching power techniques bearing some resemblance to those of Class D amplifiers.
The tubes see the speaker characteristics and vise versa, no transformer made can allow that to happen if it's in the signal path!
""switching power techniques bearing some resemblance to those of Class D amplifiers.""No, not at all, this is not a accurate statement!
It's quite obvious this is a very complicated device, completely above currently used audio knowledge!
The tubes see the speaker characteristics and vise versa, no transformer made can allow that to happen if it's in the signal path!Unfortunately, perhaps, his patent application for this idea describes it as having as an essential component, a transformer smack dab in the middle of the signal path between the output stage and the load (e.g. speaker).
No, not at all, this is not a accurate statement!
Yes it is a reasonably accurate statement, because another essential component of his idea, as described in the same patent (#5,612,646) are groups of power mosfets (also in the signal path), which are known in switching power supply and Class D amplifier circles as comprising an 'H Bridge' configuration. These power mosfets are switched between 'saturation' mode and cutoff, also typical of their application in switching power supplies and Class D amplifiers.
H Bridge is a building block for power conversion technology, so a accurate statement would be such and nothing more than the ZOTL uses modern power conversion technology to achieve it's goal, but I can't see a accurate resemblance at all to a high efficiency digital pulse width modulation Class D amp, if so, then the ZOTL equally have some resemblance to all laptops, computers, some modern TV's most all avionics and so on and so on, it's just not accurate.Maybe I miss understood your first postings, you hinted it resembling a transformer coupled amp, then it was some resemblance to a Class D amp, which would suggest a hybrid, which made my answer just as confusing, I should have said no hybrid made can allow that to happen (referring to tube/speaker characteristics), not no transformer.
OTL means output transformer less, one would assume that it means audio output transformer less, what else could it mean, which is what the ZOTL is, the key is that the device is not in the audio frequencies, which is what I mean when I say not in the "signal path" I mean audio frequencies, what other signals is there, yes there is a RF matching device in the circuitry operating at 250Kh which is made up of several transformers and mosfets, the point is, it does not operate in the audio frequency.
The amp is output transformer less and match varying speaker impedances, with a capable frequency response of DC to 250Kh, show me another tube amp that can do that, clearing showing it's an advancement in design topology.As I posted elsewhere, read Charles Hansen report, he is a switching power supply engineer, where he clearly states that this amp does not operate like a Class D amp, here is the link again.
http://www.davidberning.com/hansen_on_zh270.htm
Allan
Berning Co
I don't mean to cast aspersions on David Berning's ingenious circuit or to deny his basic claims for its capabilities, which in my estimation, include removing the typical tube amplifier output transformer nonlinearities while adding the capability to respond down to DC and retaining the ability to transform the voltage/impedance between 'primary' and 'secondary'.It's just that the means by which this is accomplished will presumably add its own sonic characteristics, and that the tendency is, since it is encouraged to generically refer to it as an 'OTL', to casually assume that no transformer at all exists in the signal path between output stage and load. But you have made reference to this already.
Btw, I've designed a 'conventional' OTL that indeed does repond down to DC (as in amplifying a DC voltage presented at its input - I deliberately rolled it off to unity gain at DC to minimize voice coil mayhem, however) with output offset referenced to ground in the tens of millivolts or less without any solid state devices in the signal path whatsoever and without resorting to the use of a feedback servo, and with some tweaks to the input and driver stages, could also respond flat to 200khz (as is, my prototype measured 3db down somewhere past 100khz into 8 ohm).
"It's just that the means by which this is accomplished will presumably add its own sonic characteristics"I would love to hear what a "sonic" characteristic of something operating at a fixed frequency of 250Kh would be?
But for argument sake let's say Maybe, so a conventional OTL with a power supply of 60Hz (audio Frequency) would not have a sonic characteristic?
One would think moving everything out of the audio frequencies would have less of a sonic character than one in the audio frequency like a 60hz one, using your own logic or any!
If low impedance, varying speaker loads where not a problem then there would be no need for transformers, you need to have the same current transfer characteristics into 2 ohms as you do into 12ohms.
If you have a speaker with a 10R impedance characteristics as flat as a ruler from 20hz to 50Kh, conventional OTL's will be the only way to go but very few speakers do that if any, this design has opened the OTL's character to varying speaker owners not just OTL friendly ones.""I've designed a 'conventional' OTL "" etc etc!!
Yeah, that's not a problem but does it match varying speaker impedances, do that and have a DC to 250Kh response and you'll have our interest, that's for sure :)
Anyway, I've spent much too much time here trying to explain something that again is very complicated indeed and we've gone over an over it in the past, this amp DOES exactly what a OTL can and what a transformer coupled amp can and it's not a solid state hybrid, so what is it, it is what it is, nothing like it.
Allan
It's much more complicated than that, it's been covered elsewhere as much as one could in such a venue, I am sure if Dave was to teach a course to post graduate switching power supply students it could be learnt.And yes, it is heck of a very complex way to get rid of a output transformer and still be able to match speaker impedance swings! If there was a easy way to do it, it would have been done already.
Allan
Berning Co.
As noted below, the Berning ZOTL uses passive parts, i.e., inductors, etc, not active solid state devices, to achieve a transformer-less output. The best explanation of his circuit I ever saw was in a 2-part article by Charles Hanson (I think) published in Glass Audio just before the demise of that lamented magazine. I understood the circuit then, but I would not want to try verbally to re-construct the concept now. IMO, it is rather silly to argue whether it is a "true" OTL or not; the question is whether it sounds good, and I think it does. I do happen to prefer my Atma amplifiers, howver. Berning is clearly brilliant, in any case.
Lew, this maybe what you're talking about, use this link, and you're right, the RF impedance device is not a active device,... just maybe.... you did understand :) :)http://www.davidberning.com/hansen_on_zh270.htm
Charles Hansen is a switching power supply engineer, even he stated that nothing in audio is related and I think he said something about it being closer to a radio station or something but please read up and refresh your memory, I am too lazy to read it again to make a accurate quote, well that's not quite true, I need reading glasses and the print is too small :)
Allan
> > > In other words the behavior of the tube becomes the signal analog to influence the active voltage to current converter which is entirely solid state===Nope.
The Bernings use a device, (not mosfets or transistor nor another gain stage)to change impedance up into mhz, and to an output suitable for driving spkrs. The -device- is a unique Berning designed inductor of sorts, has a "wound" turns ratio, this is where the confusion lies. The tube directly drives the load, through this high freq "inductor".
Inductor is a misnomer because no "inductor" has ever been made this way.
Personally I think it is every bit -otl- as circlotron only much more advanced. OK, it uses less than 1% of _some_ inductance so it is still using inductance but in a weird and unusual way. So in a way it -has- an inductor. But not at all suspect to the usual saturation and inductance distortions like every other tube amp, except circlotron and hybrid otl's.
Berning is unique, and far away the most advanced circuit for tubes period. True to thermionic dissapation as a musical fuel for amplification, it does things no other amp can. It's very stable, efficient and very low in distorion and hum. DC couled and flat response to 2hz and ultimate stability.
As far as I know Sigfreids are sold out, single ended and VG sounding. I have the PP version and would never part with it.
I was sure the amp was made by extraterrestrials, until I found another inductor hand made, wrapped on a wooden dowel. The end of the dowel had saw marks, not smooth laser cut surfaces, proving it was made by humans.
TC
"big deal, so what?"Dr. Emilio Lizardo
tcain, hi. My poor efforts to describe what David built may be compounded by misunderstanding of how his circuit works. I knew it was a matter of making the circuit do the job of letting the tube work into a load it could stand: ie adequate transfer of power to do work, all of this resultant from David's basic dislike of the audio output transformer. It was my understanding based on what David had explained about his circuit (interviews) that capturing a dynamic mimesis of the transfer characteristics of the tube in operation (voltage swing more than current) and transforming same into the realm of current more than voltage via lots of active circuitry employing much higher than audio "carrier" frequency,if you will, and semi-resonant inductors, etc. Doesn't this high frequency carrier have to be filtered/suppressed entirely from output? In this way David's amplifier reminded me somewhat of a frequency modulation transmitter. This is a very complex way to get rid of the output transformer. I am glad you like your Berning amplifier. I have one too, the EA-230 rebuilt with teflon couplers, Black Gate, and better diodes. I remember the EA-2100 with very complex Berning power supply to do away with the traditional kind using high frequency oscillator and inductors that would shift frequency under load, etc. I never heard one that sounded the same in my system. I heard 3. I was also convinced that the power supplies ( technically switch mode of unusual design as described ) radiated something because my wife and I would get severe headaches with these amplifiers turned on after about 15 minutes.
Elektron, the "is the Berning really an OTL" question has been extensively debated earlier on this asylum and several times, I think, on Audiogon. I'm sure you saw those discussions. Bottom line of all the debate was essentially "I say to-MAY-to, you say to-MAH-to", or maybe that all participants agreed to disagree.
Anyhow, this doesn't really answer Oracle's question about what would work best with his Duo's. I don't know, never heard Duo's, but my first take would be that highly efficient horns don't really need the 270, or even the M60, they're a bit of overkill. Power-wise, the Seigfried should be more than enough, as would the S30, or even the Transcendent SE OTL, or maybe even the Berning Microzotl.
no ability to give comparison withe the other amps, but I'd not part with my M60 MkII.2's, tested on many speakers, ranging from less from less than 4 ohms to higher than 16 ohms and less than 82 dB/1watt to 93 dB/1watt for less than $2500 (and still would) but just because I NEED the cash for my new home - otherwise they are PRICELESS! as referenced by a search of my posts...Just my honest opinion...please, no flames, thanks in advance...
I *like* the loudness button!
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