Semantics Hornman,
We are not measuring SPL, we are measuring Power compression, based on estimated numbers used in domestic hi-fi application, testing at 1w/2/4/8/16 rms continuous unlike music for 60 seconds then measure. We did also measure impedance mag/phase after every test. Quoting , suggesting or finding under designed speakers used in over application by some is proof of nothing.
Best you do some testing yourself, agree it's easier to jump on the VCID when selling horns, sounds good and it's already in play, similar to no NFB amplfiers..,
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I asked simple questions and you seem to reply with snide remarks, I know it isn't just directed at me, you are an equal opportunity guy! You seem to assume that nobody can read or anything in print you don't agree with is bs. I don't consider your sixty second temperature test as valid, not enough time unless you only want to know instantaneous results. I don't know anyone who only listens to a speaker for 60 second intervals, a very invalid test for temperature rise. I'll just leave it at that. Bad science give bad results.
Trolling posts (and replies) have been deleted. Offender is in the bin pending decision as to whether a permanent ban is in order.
How hard do you think it would be to blow out my BetsyK speakers?
Wild Burro Audio Labs - Fullrange Speakers - The Betsy & Betsy-K Drivers
And couldn't you make a dynamic resistance sensor to protect the speaker when the resistance increased enough to indicate a certain temperature?
Wild Burro Audio Labs - Fullrange Speakers - The Betsy & Betsy-K Drivers
And couldn't you make a dynamic resistance sensor to protect the speaker when the resistance increased enough to indicate a certain temperature?
From what I gather from the documentation:
Unless an undersized VC is being used, what I don't expect, thermal blow out would be very difficult for two connected reasons. The high efficiency in combination with the low xmax (2mm) will most likely see mechanical problems (VC former bumping the back plate) before thermal issues can occur.
It is an old fashioned idea to have high efficiency speakers that require large enclosures, but from the perspective of thermal handling it is still the best.
About the dynamic resistance sensor, interesting idea, haven't seen something like that, but can see complications. For one, the heat capacity of a voice call is fairly small, certainly a copper one, so to prevent allowable peaks from triggering the safety would require a fair amount of integration. You can probably achieve the same by using a proxy for the driver (external circuit), and I do vaguely remember having seen thermal protection circuits on speakers, long time ago.
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I have seen many woofers with voice coil burnt and melt by amplifier DC output error. BW802 membranes shoot out.
I have already thought about it, but it isn't easy: either you use the audio signal itself as a stimulus and you compute in real time the U/I quotient, but the situation is seriously complicated by the complex reactive nature of the impedance, or you inject some stealth signal, but it has to be small, subsonic and you run into S/N issues. In addition, even a VLF signal will also create some reaction from the speaker.
Re VC temperature rise:
http://members.aon.at/kinotechnik/diyaudio/dipol/space/power_compression/thermal_power_compression.pdf
IIRC, kgrlee had mentioned such a circuit with signal adaptation to VC temp estimation through a feedback resistor sensing the instantaneous current and compensating for the resulting resistance change of the VC (1980-1990 active sub, I remember the word “ACE”)
From my notes, here are some patents in which you will find fragments of this approach:
US 4,118,600
US 4,969,195
US 4,797,933
George
http://members.aon.at/kinotechnik/diyaudio/dipol/space/power_compression/thermal_power_compression.pdf
IIRC, kgrlee had mentioned such a circuit with signal adaptation to VC temp estimation through a feedback resistor sensing the instantaneous current and compensating for the resulting resistance change of the VC (1980-1990 active sub, I remember the word “ACE”)
From my notes, here are some patents in which you will find fragments of this approach:
US 4,118,600
US 4,969,195
US 4,797,933
George
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There's one - farfetched, OK - possibility: if asymmetrical signal meets asymmetrical slew rate, you get a slowly varying DC offset at the output (this was actually a test for slew rate in the 80-ies) which *might* lead to audible differences.
Jan
Jan, as Scott has already stated, it would have been very poor amplifier regarding slew rate, we do not need to bother with uA741 likes.
I have checked more topologies, the only observed difference is in case that the amplifier has high 2nd harmonic which rises with amplitude. Or with frequency when we use frequency components at top end of audio range. Some popular simple circuits would be good candidates for this test, like ZEN Mosfet amplifier, or tube SE power amplifiers. With well engineered feedback amplifiers there is no problem.
I have checked more topologies, the only observed difference is in case that the amplifier has high 2nd harmonic which rises with amplitude. Or with frequency when we use frequency components at top end of audio range. Some popular simple circuits would be good candidates for this test, like ZEN Mosfet amplifier, or tube SE power amplifiers. With well engineered feedback amplifiers there is no problem.
If a normal music signal induces slew in either direction all bets are off. One needs to get at the root cause of the slew asymmetry, it could possibly be linked to an inherently asymmetric small signal transfer (even order harmonics) rather than a hard limit. In any case it will manifest under normal testing.
I remembered last night how old this real music is "asymmetrical" stuff is and I don't expect the proponents to let go of it.
EDIT - I guess PMA and I have a psychic link
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EDIT - I guess PMA and I have a psychic link
Perfect
.I am waiting impatiently for uA741/4558 TIM stories
I think that the Hirata test should be added to anyone's criteria for making the IDEAL amplifier or preamplifier. I have tried it, and know what to avoid, but many amps have Hirata distortion. It uses asymmetrical, but DC averaged test signals. This is a misunderstood test, and has been unfortunately ignored.
DVV, my first Otala amp was actually their first prototype that they brought to Switzerland (I think for a audio show). When I heard it, I pressured them to sell it to me, and they gave in. It was THAT different from Marantz, SAE, etc at the time. I have heard power amps that were 'smoother' like the Audio Research D-150 power amp, and with more 'gusto' like the Gale power amp that I designed, but this was one successful amp DESIGN. The build quality was lousy, amateurish, etc, but it was almost magic, sonically.
The second unit that I still have came from the same period of time, I am pretty sure. I am not positive that it is as good sonically as the original prototype, but it is still darn good, today. Even better than my less expensive comp-differential jfet designs. I attribute THIS advantage to the extended Class A range in the Electrocompaniet, compared to the cheaper Parasound power amp. The slew rates of the two amps are similar.
The second unit that I still have came from the same period of time, I am pretty sure. I am not positive that it is as good sonically as the original prototype, but it is still darn good, today. Even better than my less expensive comp-differential jfet designs. I attribute THIS advantage to the extended Class A range in the Electrocompaniet, compared to the cheaper Parasound power amp. The slew rates of the two amps are similar.
"... The build quality was lousy, amateurish, etc, ..."
You lucky son of a gun, you actually had the original version of the original, or as original as it could ever hope to be.
The above quote explains why my version, which was all of that, also had that certain magic which is so elusive even today. The literally only nice thing I can say about my PCB is that it was neat. And even then, I tended to overdo the PSU, I remember purchasing two toroids from Britain, each rated at 300 VA and throwing in two 15,000 uF caps per channel. I like 'em big, meaty and juicy, you know?
These days, I have some quality Panasonic caps, 4.700 uF/50V, and I just set aside 8 pieces for that project. I plan on making two samples. One sticking to the original like postage stamp, i.e. using as many of the original parts as I possibly can, and the other in an alternative version. ike instead of using the darn expensive and hard to find dual BCY trannies hand matched (if possible, curve tracer matched too) BC 550 B low noise trannies, Fisher & Tausche 4,700 uF/63V caps (which I also set aside 8 pcs of), in short, play with it. What the hell, why not if I can? Besides, I'm curious
Actually, I want to prove the hypothesis that it's not nearly so much the parts as it is the design, something I firmly believe in. Assuming only that there's no gross mismatch of parts, copy in relation to the original.
You lucky son of a gun, you actually had the original version of the original, or as original as it could ever hope to be.
The above quote explains why my version, which was all of that, also had that certain magic which is so elusive even today. The literally only nice thing I can say about my PCB is that it was neat. And even then, I tended to overdo the PSU, I remember purchasing two toroids from Britain, each rated at 300 VA and throwing in two 15,000 uF caps per channel. I like 'em big, meaty and juicy, you know?
These days, I have some quality Panasonic caps, 4.700 uF/50V, and I just set aside 8 pieces for that project. I plan on making two samples. One sticking to the original like postage stamp, i.e. using as many of the original parts as I possibly can, and the other in an alternative version. ike instead of using the darn expensive and hard to find dual BCY trannies hand matched (if possible, curve tracer matched too) BC 550 B low noise trannies, Fisher & Tausche 4,700 uF/63V caps (which I also set aside 8 pcs of), in short, play with it. What the hell, why not if I can? Besides, I'm curious
Actually, I want to prove the hypothesis that it's not nearly so much the parts as it is the design, something I firmly believe in. Assuming only that there's no gross mismatch of parts, copy in relation to the original.
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