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Post by PaulBe on Nov 25, 2024 22:15:46 GMT -5
I very much doubt Emotiva will ever have a product with an autoformer in it... Here at Emotiva we try to provide the best "value for money" that we can... And autoformers in solid state amplifiers are the exact opposite... they offer very little benefit... for a LOT of money. And, on top of that, some of their drawbacks are in terms of sound quality... Not only do transformers limit sound quality but they make designing an amplifier with really good sound quality more difficult as well.
At least that's the case for solid state amplifiers... and I doubt we're going to have a go at tubes again any time soon.
(There's really not much case for using autoformers rather than regular transformers in tube designs.)
Incidentally, I don't want anyone to think that I just hate on McIntosh. One of the most expensive pieces of audio gear I ever purchased used was a high-end McIntosh solid state FM tuner.
It was probably the best sounding FM tuner I've ever owned (or heard). I only sold it because, back where I lived in New York, there just weren't any FM stations I found worth listening to.
And, yes, it was an excellent investment, and when I sold it I got back about what I paid for it. And, yes, I though it was attractive too.
I've just never been impressed with how their amplifiers sound. And, no, I haven't listened carefully to their newer models, but I was quite unimpressed by some of their older models that other folks raved about.
The emoji is on the second row in my ProBoards smileys (it's "  " - directly under the big toothy smile "D"... (I've always interpreted it as "a big toothy right-up-in-your-face grin"...)
In the Williamson Ultralinear amplifier the screen grids of the output tubes are connected to an extra set of taps on the output transformer. (It's not exactly a brand but a circuit topology named after the guy who thought it up... )
This connection uses that grid to provide negative feedback, which reduces distortion and improves linearity, which makes them sound cleaner. In other designs with tetrodes or pentodes that grid is tied to B+ through a resistor; triodes don't have that grid at all. In order to make an ultralinear amplifier you need output transformers with that tap included on their plate windings.
Unity Coupling was McIntosh's marketing term for a special output transformer. Normally output tubes are "plate coupled"; but they can also be "cathode coupled". With Unity Coupling the output tubes are BOTH plate AND cathode coupled. You actually have one winding in the cathode circuit of the tube, and a separate winding in the plate circuit, both on the output transformer for that channel. I'm sure you can find schematics online if you look...
This gets you a bit more power, eliminates the cathode resistor, and lowers distortion... so you get cleaner sound.
The cost is a very special transformer that nobody else uses. SOME of McIntosh's tube amps used this... but some did not.
Circlotron amps are VERY weird. They have two output devices, each connected to a separate floating power supply, with the output taken from between the cathodes. EVERYTHING floats, including both power supplies, which makes driving the output stage... interesting. The Schiit Mjolnir was a solid state Circlotron amplifier (but the Circlotron circuit dates WAY back...) (I actually heard one of the Electrovoice models... back when I was in high school... it was "vintage" even then... and it was quite impressive.)
None of it will make my head hurt, but I need a refresher because of dimmer memory. Perhaps I'll go back through my old "Audio Anthology" books from Audio Amateur. Trying to understand Mag Amps when I was in the Navy made my head hurt. Everything old is new again. So. Is Emotive going to get on the Autoformer train? What is that little bug-eyed emoji you used? It reminds me of Timothy Leary. Thanks for the short seminar. I wasn't expecting it, but I appreciate it. I should have added a JK after my question about Emotiva getting 'on the Autoformer train'. I wasn't serious. I'll stay with a couple of the old fashioned emojis and use words for anything else. |
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Post by leonski on Nov 25, 2024 22:46:53 GMT -5
In what case IS an autoformer of some advantage? Would an autoformer help with something like the Apogee Scintilla 1 Ohm?
Or some speaker with reactance issues, capacitive OR Inductive........?
Would they help with an amplifier which had problems with hi reactance speakers or very low impedance?
Not all amps are equally capable when the loads turn weird.....
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Post by KeithL on Nov 26, 2024 10:40:27 GMT -5
The answer to your question is more complex than it sounds... What transformers basically do is to allow you to efficiently connect different impedances together. So, for example, in a tube amplifier, the transformer matches the plate impedance of the output tubes to the voice coil impedance of the speaker. You connect an 8 Ohm speaker to one side of the transformer and the tubes "see" an impedance of several thousand k Ohms on the other side. (The plate impedance that tubes are designed to work with is much higher than a typical modern speaker; and it's different for different types of tubes.) So, yes, you could use a transformer or autoformer to connect a 1 Ohm speaker to the output of an amplifier... So, for example, you could use an autoformer that was designed with "a 1 Ohm tap on one side and a 4 Ohm tap on the other side". And, if you did that, the amplifier would "see" a 4 Ohm load, and would be quite happy... But, in order for that to work really well, you would need a transformer with a "1 Ohm tap" on the side that went to the speaker. This would not only be a big expensive transformer but it would be a special custom design as well. (Note that output transformers have multiple taps.. which you're supposed to match to the impedance of the speaker.) Now, in real life, you can sort of "fudge" things a little bit... so you could use a different transformer "off spec"... but you would lose much of the benefit. (Just as you can connect an 8 Ohm speaker to the "4 Ohm tap" on the output of a tube amp... but you won't get as much power because it's "a mismatch".) (You could also maybe use a transformer with a 4 Ohm tap and an 8 Ohm tap to "go from 1 Ohm to 2 Ohms instead"... but it might not work very well.) Another problem is that the answer to your second question is the exact opposite... Transformers work very well with very simple resistive loads... but they DO NOT tend to work well with complex reactive loads. If you put a nice friendly resistive load on a properly designed transformer the device on the other side sees a more or less similar resistive load at a different impedance. But, if you put a weird reactive load on a transformer, what the device driving the transformer sees is often even weirder... A capacitive load may appear as inductive, and vice versa, at various frequencies, or strange resonances may appear at odd frequencies. In short, if you intend to use a transformer with complex reactive loads, in order to work at all well it must be custom designed to work with those specific loads. So, in fact, you could design a transformer specifically to match those speakers with "a normal amplifier". But it's likely that, if you used "just a normal transformer", the results would be unpredictable... and potentially really bad. (Really bad meaning that the frequency response could be screwy... or it could be unstable and oscillate...) So, in order to be a good idea, you would really be looking at a very large and very expensive custom transformer. There is also another little issue... which is that transformers tend to be somewhat non-linear (they distort). One common solution for this, when a transformer or autoformer is used in an amplifier, is to use feedback around the transformer. There are serious limitations on how much feedback you can use - for various reasons - but it does help. However, if we were talking about "a separate transformer that just sits on the floor behind the speaker", we wouldn't have that option. (Which means that, in order to minimize distortion, the transformer would have to be even bigger, and heavier, and more expensive.) (So, in your example of those Apogees, imagine the equivalent of a 2 kW isolation transformer, only more specialized, and way more expensive, for each speaker.) In what case IS an autoformer of some advantage? Would an autoformer help with something like the Apogee Scintilla 1 Ohm? Or some speaker with reactance issues, capacitive OR Inductive........? Would they help with an amplifier which had problems with hi reactance speakers or very low impedance? Not all amps are equally capable when the loads turn weird..... |
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Post by leonski on Nov 26, 2024 14:59:57 GMT -5
keith? Mostly 'of course'. I doubt Apogee really thought that one thru!
I can't offhand think of a single amplifier.....MAYBE the Krell KSA series, which would work with that speaker.
I heard something I'd like confirmed.
Writer (with some technical chops) claimed that tube amps Didn't mind either (can't remember) inductive or capactive reactance.......But did NOT like the reverse.....
This leads me back full=circle to the Power Cube measuring system where an amp is stressed with +-30 and 60 degrees and at 8, 4 and 2 ohms.
The resultant 'shape' devines the comfort zone of an amp. Some amps are less than capable into high phase angles at low impedance......even showing signs at
what I'd consider a necessary 4 ohms.....
Than the whole thing devolves into a discussion of Power Factor.......
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Post by KeithL on Nov 26, 2024 17:30:27 GMT -5
To be honest I have not heard that specifically about tube amps... and I rather suspect that it's going to vary rather widely between different ones... As I mentioned, the output transformers used in tube amps usually have feedback around them to lower distortion. But the amount of feedback that can be applied is limited - in part because those transformers have significant phase shift. They can have phase shift at either high or low frequencies. The reason this is a problem is that negative feedback applies an inverted signal back to an earlier stage. Inverted means "phase shifted 180 degrees out of phase". If the signal at the output has additional phase shift, and too much of it, which gets added to that intentional 180 degrees, that negative feedback signal can become POSITIVE feedback. And, if that happens at any frequency, you end up with a giant oscillator at that frequency (or, as we say, a giant doorbell). Therefore the phase shift in the transformer limits the amount of feedback you can safely apply... (Too much phase shift could cause the amp to oscillate... and "a borderline amount" could cause it to sound really odd...) However, in some designs, you might have chosen to use somewhat less than that maximum, or even none. The catch is that, if you connect a load with a lot of reactance to that transformer, you may well ADD MORE phase shift... And, as a result, BUT VERY MUCH DEPENDING ON THE DESIGN TO BEGIN WITH, you could cause the amplifier to become unstable. (And this can happen at any frequency where the combination of phase shifts summed together "shifts the phase so as to result in positive feedback".) Now, to be fair, I've played with a lot of tube amps, and never run into this problem... or at least not with any real speakers... But I would say that I would be very careful in that regard... And, in this context, the bigger risk would be CAPACITANCE... for two reasons. First, that capacitance is more likely to react oddly with the inductance in a typical transformer... And, second, because SOME electrostatic speakers ARE almost purely capacitive, at least at some frequencies... But I don't actually know of any speakers that are almost purely inductive. And, yes, the Power Cube idea was interesting... Unfortunately it was only ever actively supported by one magazine (which made it sort of proprietary)... It had limited usefulness because, since nobody else was using it, it made their results difficult to compare to anyone else. And it required specialized test equipment which was somewhat expensive for back then... And the test themselves were more complicated, took more time, and so cost more to run... And the results and their implications weren't widely understood by many readers anyway... And, arguably, all it tested was "how tolerant an amplifier was of weird speakers that you probably didn't have anyway"... (So, regardless of how much sense it made in theory, it just didn't catch on.) Interestingly I've seen a few recent "power cube audio measurements" mentioned... But I don't know of anybody who uses any of them (and I haven't really looked into them)... keith? Mostly 'of course'. I doubt Apogee really thought that one thru! I can't offhand think of a single amplifier.....MAYBE the Krell KSA series, which would work with that speaker. I heard something I'd like confirmed. Writer (with some technical chops) claimed that tube amps Didn't mind either (can't remember) inductive or capactive reactance.......But did NOT like the reverse..... This leads me back full=circle to the Power Cube measuring system where an amp is stressed with +-30 and 60 degrees and at 8, 4 and 2 ohms. The resultant 'shape' devines the comfort zone of an amp. Some amps are less than capable into high phase angles at low impedance......even showing signs at what I'd consider a necessary 4 ohms..... Than the whole thing devolves into a discussion of Power Factor....... |
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Post by KeithL on Nov 26, 2024 18:32:43 GMT -5
I just can't resist the urge to make a really smarmy comment here...
Which is that I'm not sure I can honestly say that a speaker that WON'T work with most amplifiers is "well designed"... (Unless, of course, your brother-in-law is the guy who sells the one amplifier that works well with it.)
All snark aside... electrostatic speakers really have the sort of impedance and voltage profile that doesn't work well with normal amplifiers.
So one choice is to use expensive transformers, and extra bias circuitry, to adapt them to work reasonably well with normal amplifiers.
The other choice is to design amplifiers specifically designed to work well with electrostatic speakers. And, then, instead of expecting people to figure this all out for themselves, simply build those amplifiers directly into the speakers themselves.
Likewise...
If Apogee really felt that, in order to design their best speaker, they couldn't design a speaker that would work with "ordinary amplifiers"...
They could have designed their own amplifiers to go with their speakers... Or made a deal with an amplifier manufacturer to design and manufacture a custom-designed amplifier to go with them...
The argument against the need for things like the Power Cube is this... A well designed amplifier should work well with most normal speakers... A well designed speaker should work well with most normal amplifiers... And the number of exceptions to either of those requirements should be very small... (Notice how, for example, "most cars will run on most gas" these days.)
keith? Mostly 'of course'. I doubt Apogee really thought that one thru! I can't offhand think of a single amplifier.....MAYBE the Krell KSA series, which would work with that speaker. I heard something I'd like confirmed. Writer (with some technical chops) claimed that tube amps Didn't mind either (can't remember) inductive or capactive reactance.......But did NOT like the reverse..... This leads me back full=circle to the Power Cube measuring system where an amp is stressed with +-30 and 60 degrees and at 8, 4 and 2 ohms. The resultant 'shape' devines the comfort zone of an amp. Some amps are less than capable into high phase angles at low impedance......even showing signs at what I'd consider a necessary 4 ohms..... Than the whole thing devolves into a discussion of Power Factor....... |
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Post by PaulBe on Nov 26, 2024 19:23:08 GMT -5
I just can't resist the urge to make a really smarmy comment here...
Which is that I'm not sure I can honestly say that a speaker that WON'T work with most amplifiers is "well designed"... (Unless, of course, your brother-in-law is the guy who sells the one amplifier that works well with it.)
All snark aside... electrostatic speakers really have the sort of impedance and voltage profile that doesn't work well with normal amplifiers.
So one choice is to use expensive transformers, and extra bias circuitry, to adapt them to work reasonably well with normal amplifiers.
The other choice is to design amplifiers specifically designed to work well with electrostatic speakers. And, then, instead of expecting people to figure this all out for themselves, simply build those amplifiers directly into the speakers themselves.
Likewise...
If Apogee really felt that, in order to design their best speaker, they couldn't design a speaker that would work with "ordinary amplifiers"...
They could have designed their own amplifiers to go with their speakers... Or made a deal with an amplifier manufacturer to design and manufacture a custom-designed amplifier to go with them...
The argument against the need for things like the Power Cube is this... A well designed amplifier should work well with most normal speakers... A well designed speaker should work well with most normal amplifiers... And the number of exceptions to either of those requirements should be very small... (Notice how, for example, "most cars will run on most gas" these days.)
keith? Mostly 'of course'. I doubt Apogee really thought that one thru! I can't offhand think of a single amplifier.....MAYBE the Krell KSA series, which would work with that speaker. I heard something I'd like confirmed. Writer (with some technical chops) claimed that tube amps Didn't mind either (can't remember) inductive or capactive reactance.......But did NOT like the reverse..... This leads me back full=circle to the Power Cube measuring system where an amp is stressed with +-30 and 60 degrees and at 8, 4 and 2 ohms. The resultant 'shape' devines the comfort zone of an amp. Some amps are less than capable into high phase angles at low impedance......even showing signs at what I'd consider a necessary 4 ohms..... Than the whole thing devolves into a discussion of Power Factor....... It's not hard to design a normal solid state amp that drives electrostatic speakers or others with highly reactive loads. Use feed forward techniques and/or limit the number of poles in the feedback loop. Quad did it and drove ESL-57s. Acoustat did it and drove their electrostats. Threshold does it. Benchmark does it. I did it with my own redesigns of Audire Parlando and Forte amps. I could drive a 5uf capacitor on the output with a 10KHz square wave and almost no ringing. This is not a big deal. |
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Post by leonski on Nov 27, 2024 1:50:26 GMT -5
www.audiograph.seClearly, not all amplifier manufacturers buy into making an amp work into highly reactive loads. But I would like more information on what TUBE amps, working thru a transformer will put up with... This was a LONG time ago. Nearly 50 years past. I visited a friends house to listen to Magnepan speakers. I ended up buying the MG1 which I kept for years. But these guys were inventor types an had some electrostatic speakers to try with their new amplifer.....a DIY effort. It went out of control, emitted a 'chirp' and that was THAT.
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Post by audiobill on Nov 27, 2024 7:40:27 GMT -5
This thread has drifted so far from its title....time to lock it down?
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Post by PaulBe on Nov 27, 2024 8:15:42 GMT -5
This thread has drifted so far from its title....time to lock it down? Probably  Nothing much more to say about 'Bose Buys McIntosh and Sonus Faber', so it meandered... |
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Post by KeithL on Nov 27, 2024 9:57:59 GMT -5
Again, it is certainly quite possible to design a tube amplifier that will work just fine into highly reactive loads, but many of them will not safely do so. Whether that is true for a specific amplifier model is going to depend on several very specific details of its design (there are a lot of different types and designs of tube amplifiers). I guess it's also worth mentioning that the "chirp" you heard was probably the amp going into oscillation... Which can potentially damage the speaker or destroy the output transformer... (Which is usually the most expensive single part on a tube amp.) Also note that Magneplanars are NOT electrostatic speakers are are NOT an especially reactive load. They have a relatively low impedance, and are relatively inefficient, and some models have actual ribbon tweeters, which may dip even lower at higher frequencies. Electrostatic panels are an almost purely capacitive load... and also tend to require very high drive voltages... both of which are unusual requirements. Neither of these characteristics applies to Magneplanars. With electrostatics you either need a specially designed amplifier or a transformer to step up the voltage of the drive signal. So, if you connect then to a normal tube amp, you're probably stacking two transformers one after the other... Which is sort of asking for trouble. www.audiograph.seClearly, not all amplifier manufacturers buy into making an amp work into highly reactive loads. But I would like more information on what TUBE amps, working thru a transformer will put up with... This was a LONG time ago. Nearly 50 years past. I visited a friends house to listen to Magnepan speakers. I ended up buying the MG1 which I kept for years. But these guys were inventor types an had some electrostatic speakers to try with their new amplifer.....a DIY effort. It went out of control, emitted a 'chirp' and that was THAT. |
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Post by KeithL on Nov 27, 2024 10:26:28 GMT -5
I'm sure it will die out on its own... I don't see a problem - as long as nobody is mourning the loss of the original "path" of the thread... This thread has drifted so far from its title....time to lock it down? |
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Post by marcl on Nov 27, 2024 10:44:29 GMT -5
I'm sure it will die out on its own... I don't see a problem - as long as nobody is mourning the loss of the original "path" of the thread... This thread has drifted so far from its title....time to lock it down? And often the meandering paths lead to good questions and informative answers! |
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Post by bluemeanies on Nov 27, 2024 13:02:57 GMT -5
I hate to say it, but my practically all Mc and Kef Blade system somehow brings me great satisfaction, well beyond solely sonic virtues… Look, I totally get it, but sitting here bathed in all that Mc goodness makes my wife and me happy and it just might you too. For me, it,s like a return on a life well worked and lived, I don,t need to justify it on some abstract technical virtue/ value argument, though I could easily do that too. I started in this in 1963. Who would like to stop over for a listen and a drink? peace, I love the way you use the English language. Very well put audiobill. No need for for me to justify or apologize for acquiring a dream I had since I was a teenager. |
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Post by bluemeanies on Nov 27, 2024 13:04:59 GMT -5
Especially in this particular case I think I would include "sound quality" on that list as an actual separate item... To be blunt... I've seen and heard some vintage McIntosh gear... And, while a lot of it was beautifully crafted, built like a tank, and had great resale value... And I personally think that it looks nice... but opinions vary there. BUT...not all of it actually sounded especially good to me... (Not at all bad... but not better... and not the best... compared to other far cheaper gear.) To be fair, I owned one of their high end FM tuners years ago, and the sound quality was really awesome - for FM. I think I can fairly say that it was the best sounding FM tuner I've ever heard... before or since. (I bought it used, for over $1000, and I did get back what I paid for it when I sold it a few years later, so there is that.) But I've heard some of their older amps and, to be honest, I was not especially impressed... I actually did have an opportunity to hear one of their older big solid state amps next to a pair of our old XPA-1's... And, I'm sorry, but the XPA-1's sounded distinctly cleaner and more detailed... The McIntosh amp sounded "nice" but noticeably NOT great. McIntosh has changed hands several times over the years... And I'm happy to see the brand survive... (But I won't be buying any of their gear any time soon.) Some like Nissan Versas, and some like Porsches..... BAM! |
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Post by KeithL on Nov 27, 2024 15:24:44 GMT -5
I really DO wish that Emotiva would get some of those big blue meters... The prettiest amp I've ever owned was an old Marantz 140... As an amplifier, it was nice, but not really that impressive... but it had big beautiful blue meters... It also had a dress cabinet with real walnut veneer on it... And the modern McIntosh amps, with the silver trim, black panels, and big blue meters, are really beautiful. (Most McIntosh gear looks really nice.) But I really hate the green lighting they use with the tubes on some of their new gear... If you're going to light tubes up with LEDs then the only proper color to light a tube is orange; to me green just looks... odd. As you say... we are all entitled to our opinions... Some like Nissan Versas, and some like Porsches..... BAM! |
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Post by leonski on Nov 27, 2024 15:29:46 GMT -5
Again, it is certainly quite possible to design a tube amplifier that will work just fine into highly reactive loads, but many of them will not safely do so. Whether that is true for a specific amplifier model is going to depend on several very specific details of its design (there are a lot of different types and designs of tube amplifiers). I guess it's also worth mentioning that the "chirp" you heard was probably the amp going into oscillation... Which can potentially damage the speaker or destroy the output transformer... (Which is usually the most expensive single part on a tube amp.) Also note that Magneplanars are NOT electrostatic speakers are are NOT an especially reactive load. They have a relatively low impedance, and are relatively inefficient, and some models have actual ribbon tweeters, which may dip even lower at higher frequencies. Electrostatic panels are an almost purely capacitive load... and also tend to require very high drive voltages... both of which are unusual requirements. Neither of these characteristics applies to Magneplanars. With electrostatics you either need a specially designed amplifier or a transformer to step up the voltage of the drive signal. So, if you connect then to a normal tube amp, you're probably stacking two transformers one after the other... Which is sort of asking for trouble. www.audiograph.seClearly, not all amplifier manufacturers buy into making an amp work into highly reactive loads. But I would like more information on what TUBE amps, working thru a transformer will put up with... This was a LONG time ago. Nearly 50 years past. I visited a friends house to listen to Magnepan speakers. I ended up buying the MG1 which I kept for years. But these guys were inventor types an had some electrostatic speakers to try with their new amplifer.....a DIY effort. It went out of control, emitted a 'chirp' and that was THAT. Darn Tootin' it was an ultrasonic 'burp'. Amp ceased to function instantly. Builders were 'chagrined' to say the least. I've seen measured data where 'Stats go highly capacitive over maybe 10khz and reach 50 degrees at the limit. This is killer BUT given the power requirements of the upper octave? Not awful. IF the amp is OK with that particular load. And yes, You summed up panels (magnepan) quite nicely. Mostly benign load with very low sensitivity. The ribbon is epic and on the short list of 'finest of its type'...... I would personally like to see an All Out assault on the Magnepan style speaker. Niobium Magnets? Slightly wider 'gap' . Configure as Push-Pull (magnets on both sides of driver). And if it ever became available? Sheet Graphene for the driver........ I still wonder about tubes / transformers and load. Tubes and 'big box' speakers work well together. But I wonder, for example, If KLIPSCH Forte IV would be comfortable with tubes? Speakers are easily 95 or 96db sensitive so power isn't the big issue..... Certainly My Flea Power amp from Parts Express would work........and might even get 'loud'........But that's SS not tube...... Measured data shows some big reactance swings which I'm just not comfortable with when combined with TUBES. I wish I could afford a Pass Labs amp. The 30-a-side 'A' amp would be wonderful.......The old 30.5 entry also had about 6db headroom.......which is insane but confirmed by stereo-hole.....THAT should satisfy those Klipsch! |
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Post by KeithL on Nov 27, 2024 17:52:59 GMT -5
The information you have is more or less correct... The actual PANEL in an electrostatic speaker is almost PERFECTLY capacitive... it really is JUST a capacitor... You literally have two plates... with an insulating gap between them... which is how you make a capacitor... So, if one is anything less than that, then it's because series resistance has been added to shift it at least slightly resistive... A typical electrostatic panel also requires a drive signal in the thousands of volts... And it also requires a multi-thousand-volt DC bias (at virtually no current)... Some older designs used transformers... or even capacitor coupling... Others used a really high voltage output stage and direct-coupled it to the panels... And, yes, pretty awful for an amplifier not specifically designed to handle that sort of load... However, and even worse, the alternative is to use a transformer to boost the audio signal voltage. You now have a transformer, connected to an almost purely capacitive load, and operating at VERY high voltages. And transformers do very weird things with reactive loads... especially at very high frequencies... And they also have their own inductance and inter-winding capacitances... So you can see things like a reactance that flips from inductive to capacitive on either side of some resonant frequency... And multiple resonances at multiple very high frequencies. The upshot is that it takes VERY careful design to do this in a way that is in any way reasonable for an amplifier to drive. There's also yet another "issue" with tube amps in general... They REALLY don't like to have their outputs clipped... especially into a very light or open load... You NEVER want to drive a tube amp into hard clipping with no load on it. Solid state amps are often fussy about having their outputs shorted... because it will draw excessive current. But, if you run a tube amp into hard clipping with NO LOAD, it will generate excessive voltage. And this can trash your output transformers almost instantly. Basically, when you feed square waves through a transformer, you create a very rapid jump in the magnetic field... And, since the output voltage of the transformer is proportional to the rate of change in the magnetic field... The result of this is a REALLY high voltage spike at each edge of that square wave... This is how ignition coils make big ass sparks from relatively low voltage inputs... And, if you do this to an amplifier with an output transformer, you will destroy the transformer almost instantly... (And this can also happen if you let the amplifier go into uncontrolled oscillations.) Most of those old "big box" speakers had very high efficiency and a relatively benign impedance. They also have plenty of mechanical damping so they don't really need an amplifier with a high damping factor... That's why they work pretty well with most low powered amplifiers of pretty much any sort. Bear in mind that "headroom" is really just a sort of humbug... or more accurately a "derating". It's simply the difference between "rated continuous power" and "peak power"... (It was really only a thing when power supplies were expensive so it made sense to design an amp that could deliver a lot of power for only a short time.) So, for example, our BasX A2 is "160 watts per channel" with no "headroom" rating... But, by those same exact numbers, we could call it "a 16 watt amplifier with a whopping 10 dB of headroom"... Or we could call it "a 32 watt amplifier with over 6 dB of headroom"... Those would all be equally accurate claims for that amp... So, yes, a 30 watt amplifier that can deliver "120 watts instantaneous peak" is pretty cool... But how impressive that is depends on what it costs compared to other amps of similar power... And, of course, how it sounds... I haven't actually heard one of the little Pass Labs amps in person, and I have heard good things about them, but they are sort of pricey. But, yes, they should work really nicely with high efficiency speakers like Klipsch's. But, if you want to play with low powered amps, and high efficiency speakers, you might want to pick up one of these to play with... www.aliexpress.us/item/2255800686745620.html(And don't forget to pick up a 12V wall wart to go with it.) The ratings, low as they are, are still pretty generous... And their measured performance is actually sort of pathetic... But they actually sound quite nice when connected to easy-to-drive speakers... Incidentally... Magneplanars have a conductive voice coil attached to an insulating substrate... So you would probably want to keep the Kapton substrate (Kapton is actually pretty impressive)... And I don't think you'd do much better than Neodymium for magnets... But graphene conductors would be interesting since they could be much lighter than copper or aluminum... ....................................... Darn Tootin' it was an ultrasonic 'burp'. Amp ceased to function instantly. Builders were 'chagrined' to say the least. I've seen measured data where 'Stats go highly capacitive over maybe 10khz and reach 50 degrees at the limit. This is killer BUT given the power requirements of the upper octave? Not awful. IF the amp is OK with that particular load. ...................... I still wonder about tubes / transformers and load. Tubes and 'big box' speakers work well together. But I wonder, for example, If KLIPSCH Forte IV would be comfortable with tubes? Speakers are easily 95 or 96db sensitive so power isn't the big issue..... Certainly My Flea Power amp from Parts Express would work........and might even get 'loud'........But that's SS not tube...... Measured data shows some big reactance swings which I'm just not comfortable with when combined with TUBES. I wish I could afford a Pass Labs amp. The 30-a-side 'A' amp would be wonderful.......The old 30.5 entry also had about 6db headroom.......which is insane but confirmed by stereo-hole.....THAT should satisfy those Klipsch! |
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Post by leonski on Nov 28, 2024 2:14:05 GMT -5
The Ratings Game is what Pass relied on. RATED at 30x2 pure class 'A'.....the 6db point was clearly AB which is
no secret.
So? My 'mythical' Klipsch Forte IV? 30 class A watts is quite a LOT and certainly into medical damage / eviction territory.
Never heard Kapton and Magnepan in the same breath....Mylar? Yes. Just imagine 15 watts continuous with 10db peaks!
the Neo magnets are a couple orders of magnitude 'beefier' than the refrigerator types used. As a matter of fact?
The NEO magnets can be dangerous. A Snap-Pinch will break skin at least. No compromise in the handling of NEO magnets.
What you want is a 2-Fer. Greater space between magnet / polepiece and diaphragm. At the same time? Far more powerful
magnetic field. So you get Higher senssitivity AND dynamic improvement.
Next full generation Maggies? Graphene sheet, but NO 'adhesive' conductors. Graphene must be doped for conductivity.....
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" - directly under the big toothy smile "D"...
Nothing much more to say about 'Bose Buys McIntosh and Sonus Faber', so it meandered...
