Actually, Nige, that may be some waystation, because in the end, the best overall solution is an active speaker.
Just imagine the bass or tweeter being connected to the driving amp by something like 10 inches of wiring of your choice, no resistors, capacitors or inductors in the way to cause nasty phase shifts and decrease natural driver efficiency, and so forth.
Under such circumstances, I believe some of the available all-in-one-chip power amplifiers would do just fine, possibly even very well. After all, they'd be seeing as clean and easy load as possible.
Assuming you select your power amp chip well, and are not stingy about it, and with no passive crossover losses, you might be able to get some awesome dynamics in a room.
Not to even mention the Games Unlimited you get at no extra charge. For example, if you have a say 96 dB/2.83V/1m efficient tweeters, which are powered by a say 50 WRMS chip power amp, you could easily add a series resistor and not have to worry about drive power.
Or, if your really went for it, you might consider the opposite direction, such as putting two tweeters in parallel, because again, practically nothing stands in the way between them and power amp driving them.
MOST interesting thoughts become possible.
The only caveat that comes to mind is the problem of cables linking the active speakers and the command center, the preamp. Personally, I'd think hard about balanced lines, but obviously only after first deciding where to place the electronic crossover. If placed inside the speaker, then it would also act as a buffer for the chip power amps.
Just imagine the bass or tweeter being connected to the driving amp by something like 10 inches of wiring of your choice, no resistors, capacitors or inductors in the way to cause nasty phase shifts and decrease natural driver efficiency, and so forth.
Under such circumstances, I believe some of the available all-in-one-chip power amplifiers would do just fine, possibly even very well. After all, they'd be seeing as clean and easy load as possible.
Assuming you select your power amp chip well, and are not stingy about it, and with no passive crossover losses, you might be able to get some awesome dynamics in a room.
Not to even mention the Games Unlimited you get at no extra charge. For example, if you have a say 96 dB/2.83V/1m efficient tweeters, which are powered by a say 50 WRMS chip power amp, you could easily add a series resistor and not have to worry about drive power.
Or, if your really went for it, you might consider the opposite direction, such as putting two tweeters in parallel, because again, practically nothing stands in the way between them and power amp driving them.
MOST interesting thoughts become possible.
The only caveat that comes to mind is the problem of cables linking the active speakers and the command center, the preamp. Personally, I'd think hard about balanced lines, but obviously only after first deciding where to place the electronic crossover. If placed inside the speaker, then it would also act as a buffer for the chip power amps.
Unless you listen to continuous sine waves, or many modern CDs with almost no dynamic range, the transformer has plenty of time to recharge the caps during the quieter periods. The higher the voltage they recharge to (set by the secondary voltage, not VA - within reason) the more you can droop when the next music peak comes along.a.wayne said:
As I said, it is counterintuitive so some people will find it hard to believe. Do the maths, or read the other thread and believe the maths we have done. The right transformer can be better than the bigger transformer. I guess I am arguing for design, not fashion following.
Of course, if you have to sell a product then you may need to degrade its performance by putting in a bigger transformer which can supply more current than necessary in preference to one with a bigger secondary voltage which can provide more headroom.
What you are talking about, gentlemen?
What capacitance? What Joulies?
Suppose, I have an amp. It draws 1 A constantly, it has a source follower output supplied by current source. Let's take the worst scenario: output resistance of the source follower is 1 Ohm, dynamic resistance of current source is 1 KOhm only. That means ripples and sag from power supply re 60 db down on speaker terminals. So if they are huge, like 1 Volt, there will be -80 dB S/N level on speaker terminals caused by PS ripple and sag. Now let's calculate which minimal capacitance do I need for -80 dB or below?
It's the practical question based on strong arithmetic theory. No esoteric at all.
What capacitance? What Joulies?
Suppose, I have an amp. It draws 1 A constantly, it has a source follower output supplied by current source. Let's take the worst scenario: output resistance of the source follower is 1 Ohm, dynamic resistance of current source is 1 KOhm only. That means ripples and sag from power supply re 60 db down on speaker terminals. So if they are huge, like 1 Volt, there will be -80 dB S/N level on speaker terminals caused by PS ripple and sag. Now let's calculate which minimal capacitance do I need for -80 dB or below?
It's the practical question based on strong arithmetic theory. No esoteric at all.
This is the Krell "secret" of course - what they did was realise that minimising voltage droop was the name of the game, and they threw a lot of resources and money at refining that. Hence the infamous Krell bass, simply because the power supply didn't collapse when some meaty notes needed to be played.
That the rest of the amp wasn't too sharp at reproducing everything else probably didn't worry them too much ...
Frank
This is the Krell "secret" of course - what they did was realise that minimising voltage droop was the name of the game, and they threw a lot of resources and money at refining that. Hence the infamous Krell bass, simply because the power supply didn't collapse when some meaty notes needed to be played.
That the rest of the amp wasn't too sharp at reproducing everything else probably didn't worry them too much ...
Frank
Infamous bass .....
I'm wagering you have not heard much Krells, if using them on an 8 ohm speaker load, then its a waste , put them on Maggies, apogees, or anything with a 4 ohm impedance or lower and they shine thru. While not the best sonically, they were easily top tier of the day ...
I think you misunderstood me, I just said exactly what you repeated: Krell could do brilliantly driving extremely severe loads, maintaining bass performance at high volumes.Infamous bass .....
I'm wagering you have not heard much Krells, if using them on an 8 ohm speaker load, then its a waste , put them on Maggies, apogees, or anything with a 4 ohm impedance or lower and they shine thru. While not the best sonically, they were easily top tier of the day ...
Here, I will again put in a good word for the Australian ME amplifiers, which back then could easily out-Krell a Krell, how about 1500W into 1 ohm per channel, continuous, both channels driven. 5KVA transformer, 300,000uF, switchable class A operation. The bloke behind it had problems in the interim, but has re-emerged, at the moment with far less ambitious units: Home
Frank
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It's "hidden" in that last link, in my previous post! Home ... me-au.com ...ME, 1500 watts @ 1ohm ! what is ME, I will search for it , it's my destiny .....
EDIT: Do you really need a thousand little caps , I'm limited to 8 , it's a round number and in stock ...
Nope, the number of caps doesn't have to be huge, though that ME used 92, I seem to recall ...
. It's about the right values, in the right place ... patience, Grasshopper ... Frank
How about 2,000/3,600/5,400 Watts into 8/4/2 Ohms?
From experience, I know it will do more into 1 Ohms, but if the worst comes to worst, and it halves the power into 1 Ohm, that's still 2,700 Watts into 1 Ohm ...
Karan Acoustics, model KA M 2000. 40 Sanken RET BJTs at the output, 132.000 uF of capacitance, net weight 76 kg / 167 lbs.
Karan Acoustics | Manufacturer of High-End Audio
Drool, Wayne.
And investigate a direct link to the Hoover dam power station.
From experience, I know it will do more into 1 Ohms, but if the worst comes to worst, and it halves the power into 1 Ohm, that's still 2,700 Watts into 1 Ohm ...
Karan Acoustics, model KA M 2000. 40 Sanken RET BJTs at the output, 132.000 uF of capacitance, net weight 76 kg / 167 lbs.
Karan Acoustics | Manufacturer of High-End Audio
Drool, Wayne.
And investigate a direct link to the Hoover dam power station.
There's an interesting point I'd like to raise on the subject of load tolerance.
Look at the schematics of any Harman/Kardon amp, and on the specs page, you'll find their statement on "HCC" ("High Instantaneous Currect Capability"), with numbers like 75 or more Amps. On the one hand, as such, that means diddly because it doesn't state any of the conditions, what load, what time interval, etc.
On the other hand, their quite commercial fare (in other words, serial products, not the up market Citation series), such as my own HK 680 (nominally 85/130W 8/4 Ohms, hardly revolutionary), are hard to believe when put on the test bench and made to jump through loops. With a time interval of 20 milisecs, as per the IEC standards, it kicked a very creditable 520 Watts into 2 Ohms.
And all this from a power transformer which, judged by the protection fuses, is around 500 VA, with separate windings for the left and right channel, and obviously, separate power supplies for each channel. These consist of a full wave bridge rectifier and two 8,200 uF caps. The supply lines are nominally +/- 52 V (off load). The actual output stage cnsists of a 5W predriver, 35W driver and two 130W output pairs. Global NFB is 12 dB.
So - how does one manage such power outputs from what is here a VERY modest power supply, apart from some quality engineering?
Look at the schematics of any Harman/Kardon amp, and on the specs page, you'll find their statement on "HCC" ("High Instantaneous Currect Capability"), with numbers like 75 or more Amps. On the one hand, as such, that means diddly because it doesn't state any of the conditions, what load, what time interval, etc.
On the other hand, their quite commercial fare (in other words, serial products, not the up market Citation series), such as my own HK 680 (nominally 85/130W 8/4 Ohms, hardly revolutionary), are hard to believe when put on the test bench and made to jump through loops. With a time interval of 20 milisecs, as per the IEC standards, it kicked a very creditable 520 Watts into 2 Ohms.
And all this from a power transformer which, judged by the protection fuses, is around 500 VA, with separate windings for the left and right channel, and obviously, separate power supplies for each channel. These consist of a full wave bridge rectifier and two 8,200 uF caps. The supply lines are nominally +/- 52 V (off load). The actual output stage cnsists of a 5W predriver, 35W driver and two 130W output pairs. Global NFB is 12 dB.
So - how does one manage such power outputs from what is here a VERY modest power supply, apart from some quality engineering?
Wonder if those are continuous ratings ... the ME used continuously variable speed fans, with higher transformer rating and bigger, lower impedance capacitance bank. In a slugging competition the ME might just have the edge ...
Sorry, just doing some flag waving here,
Frank
It's perfectly all right, Frank, it's a fair question.
Yes, those are continuous power ratings. The thing is a monster, I've seen and heard it, but not wanting any hernia, I never really tried to lift it.
What I cannot tell you is how long can it sustaing full power levels with sine waves.
My most delightful surprise overall though was that it sounds exactly like all other Karan amps, power and integrated, do. That's the one thing I take my hat off to Milan, all 6'6'' and 300 lbs of him, he has managed to keep his sound more constant and consistent than most out there in the High End. My KA-i180 integrated, delivering 180/250 WRMS into 8/4 Ohms, sounds exactly the same as that beast, only that beast has more of it to flaunt.
And yes, all his amps have that elusive exquisite feeling of limitless power, as if you couldn't overload it no matter what you do. It's an illusion, of course, but one I would gladly go for. Then again, given that the entry level with Milan is 22 dBW or 180 WRMS, perhaps I shouldn't be surprised. You DO expect 180 Watts to sound easy.
I've been friends with Milan for some 14 or 15 years, and I've never stopped marvelling when with him. He's a giant, literally, yet I don't get to meet such gentle people as he is. I'm passionate about music, but he's way ahead of me. You should see his lab playground, it's a sight to behold, lots of projects later rejected for some reason, yet fully functional. His home loudspeakers are based on JBL professional components and weigh in at around 110 kilos (250 lbs) each. Efficiency of some 96 or 97 dB/2.83V/1m, driven by his behemoth mono blocs, capable of 33 dBW, theoretically capable of music peaks of 129 dB. I mean, like, WOW!
Nige, do take a long and hard look at RAAL - ADVANCED LOUDSPEAKERS .
That's one passionate dude, who's been at it for over 12 years now. His drivers can be found in several US made speakers, don't know exactly which, wasn't interested, but I know his main customers are in USA.
I don't have much experience with Aca's ribbons (BTW, his nickname locally is "Aca Ribbon"
), but I did spend a day at his home, to which he has added an entire auditorium, properly engineered for its acoustic properties, listening to his test speaker. It was a 2 way design, using a Volt bass driver, I think it was a 12 incher, and of course his ribbon. Not wishing to be some promoter of Serbian manufacturers, I'll say just this - that was the ONLY 2 way speaker I have ever heard which I would snap up for myself just like that and never look back. The clarity is astonishing.From what I know ribbons were made from surplus radar magnets after the war . When the cheap source dried up so did they . The Wharfedale Isodynamic headphone was transformed into the Emit tweeter if rumor is right . Tandy ( Radio Shack ) sold a version . They resemble mini Magnaplanars . I feel CD made us less able to discern when a tweeter was more than just something to remind us of high frequencies .
Thanks for the links Dvv , plenty of reading .
Thanks for the links Dvv , plenty of reading .
How about 2,000/3,600/5,400 Watts into 8/4/2 Ohms?
From experience, I know it will do more into 1 Ohms, but if the worst comes to worst, and it halves the power into 1 Ohm, that's still 2,700 Watts into 1 Ohm ...
Karan Acoustics, model KA M 2000. 40 Sanken RET BJTs at the output, 132.000 uF of capacitance, net weight 76 kg / 167 lbs.
Karan Acoustics | Manufacturer of High-End Audio
Drool, Wayne.
And investigate a direct link to the Hoover dam power station.
Yes , Magic ! he is getting more power out than he is putting in ....
Sorry to interrupt the very interesting ongoing conversation to go back to this.
It's actually easy to get that power level for such a short time, and almost couldn't be otherwise. And the 2 Ohms just makes it easier.
Starting at 0 watts, the no-load voltage would apply. So initially you'd get 52v/2 ohms = 26 amps. And 26 squared x 2 = 676 Watts.
And if the rail voltage was allowed to drop by 20 volts over 20 ms, then using
I = C dv/dt = .0164 • 20/.02 = 16.4 amps gives 16.4 • 16.4 • 2 = 538 Watts.
Parasitics and other things were ignored in those calcs but they're close-enough to see how it's possible.
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