Interesting, so that is where the sometimes quoted guide that you should design for 5x the current that the nominal impedance suggests. Another good reason for active speakers.
When I built a phono preamp powered by a regulated supply with remote sensing, I spent some time thinking about where to connect the sense wires. I ultimately opted to connect the supply and sense where the supply entered the preamp board. I often wonder what difference, if any, there might have been if I terminated the sense wires elsewhere, say at the input stage opamp power supply pins, or even the output stage. I copped out because I couldn't think of anything better.
Indeed, that is one reason why, for example, Linkwitz Pluto speakers work so well: even the lowly LM3886 performs well with a benign load.
This is one of the factors that separates a 'marginal' amp from a 'successful' amp. Usually, more output devices gives both the added peak current and increased safe area.
Easy speaker loads are for sissies. A PROFESSIONALLY designed amp must take on just about all speaker loads. Just like an automobile should be able to handle difficult roads as well as easy ones.
Mooly, I believe that was Kenwood/Trio's Sigma drive system, which used a special return wire from the speakers back to the amp, which included the soeakers into the overall NFB loop, or some such. It was said to provide typical damping factors of 60 dB into nominal 8 Ohms loads.
It was used on Kenwood/Trio's upper model range products to the early 80.ies, when it slowly disappeared. "Upper" model range includes their integrated amps as well, I heard it on a model 1000 integrated amp, the one packaged into two separate plastic cases, the added one housing the PSU. It did produce a difference in sound, that I remember, but what I never did make up my mind on was which mode was better sounding. Those were the days of the high speed wars between Kenwood, Pioneer and Sansui, when you had to have 200 V/uS or better. This only complicated matters.
This reminds me of Enzo Ferrari's coment that aerodyinamics are for the manufacturers of weak engined cars, a real deal is a car with 500+ horse power to force a solution of all problems. And that may well be so, but once you investigate fuel consumption, you soon realise that above 60 mph 80% of the power used is used to overcome aerodynamic resistence.
That said, I do agree that the main problem of an amp designer is to provide suffiient quality and quantity of power for the amp to drive almost anything somebody called a speaker, and as we have seen, a lot comes under that heading. While my own speakers are really easy to druive loads, I am still on a diet of four pairs of output devices, each being rated at 230W (ON Semi MJL4281) or at least 200W (ON Semi NJW3281). A good reserve never hurt anyone, and besides, my easy load speakers are the exception rather than the norm.
So don’t bother building the roads in a proper way and have the citizens all buy luxury 4x4 of- road monsters (they will be thrilled by the added road adventure as their everyday lives is deprived from any excitement)
One part of the market is feeding the other (raison de entrée)?
I would understand the release of a loudspeaker with very difficult impedance curve, only when the same drivers on the same enclosure had been tested with cautiously designed x-overs and found lucking in acoustic terms (it’s my experience that loudspeakers with complex passive x-overs don’t win the battle of “first listening impression”. It takes some time to appreciate their qualities).
Mr Baxandal in his article (page 15, right column) praises the almost purely resistive 4 Ohm impedance of KEF 104/2
Attachment is from this excellent book
High Performance Loudspeakers, 6th Edition: Amazon.co.uk: Martin Colloms: 9780470094303: Books
George
Attachments
dvd and Mooly.
The schematic of Kenwood Basic M1 is at HiFi Engine - Owners and Service Manuals
The speaker remote sensing is a very simple RC circuit ending at the input differential pair, in parallel with the amplifier's NFB loop.
This is not the whole story with these amplifiers though (read their DLD circuit)
George
The schematic of Kenwood Basic M1 is at HiFi Engine - Owners and Service Manuals
The speaker remote sensing is a very simple RC circuit ending at the input differential pair, in parallel with the amplifier's NFB loop.
This is not the whole story with these amplifiers though (read their DLD circuit)
George
According to the reviews at the time, there was a dustcap resonance around 2kHz, the fix for which caused the impedance problem. Odd given the Wilson mystique of custom modded drive units just for them. Still a cludge, but at least then only high end amplifiers will be demonstrated with your speakers!
So how come the more you pay for a car the less likely it is to do well on difficult roads? Actually come to think about it, how come Audi can't make a car that can handle british roads at all!
You would seem to indicate that you compare your amplifiers with a porsche cayenne turbo or range rover sport?
Well, the cheaper a car is the more likely it is to be aimed at world's poorer markets, which wil onsequently mean poorer roads as well. My Daewoo Nubira went through three sets of ahock absorbers in its 100.000 km limit, when according to the manual, it should have gone through only one. It is a superbly soft and comfy ride, paid for in poorer road holding and triple the shock absorber changes. That car was never meant for Serbian roads, which are notorious for poor maintenance.
An AUDI will bust your behind because it's relatively hard to drive in, but it sticks to the road very well and you will really have to drive like a suicidal madman to make it skid on any tarmac. Regarding British roads, it depends much on which roads exactly, In the Somerset countryside, the biggest problem with most roads was the mud spread all over them from passing tractors and other agricultural machinery, an unlikey problem in the heart of say London.
An AUDI will bust your behind because it's relatively hard to drive in, but it sticks to the road very well and you will really have to drive like a suicidal madman to make it skid on any tarmac. Regarding British roads, it depends much on which roads exactly, In the Somerset countryside, the biggest problem with most roads was the mud spread all over them from passing tractors and other agricultural machinery, an unlikey problem in the heart of say London.
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A common confusion, you do not need a hard ride to get good grip. In fact a softly suspended car will often handle better. Audi's are hard as rock because drivers think that means sporty. Also meat sacks are poor at handling body roll.
Crazy thought: how about fixing the driver or choosing a better one? I know, crazy, what in the world could I be thinking.
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