...because no matter what resistance drivers have, dumb designer can create dips using L and C components of crossovers only.
I was referring to efficiency losses with power, due to thermal coefficient. (What do you think ?)
But i have the answer:
Constantan conductivity = 49 E-8
Coper= 1,7 E-8
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I think Esp was probably thinking that constantan has near-zero variation in resistance vs temp. Not about its thermal conductivity coefficient.
Right, I assumed that the conductivity of Constantan was somewhere between that of copper and nickel, but mother nature is doing everything possible to put us sticks in the wheels. 😀
maybe maybe maybe
Maybe maybe maybe. try it. Sim it. what ever. then lets talk about it. BTW -- The Rs I used in the feedback was 0.1 Ohm in series with feedback resistor to ground, according to my notes. If you think this will make all the difference in the world, then lower it and change amps feedback R's as needed.
A simple R in series with speaker isnt the same effect as in the feedback loop, of course, and the thd wouldnt be reduced if not in the fb loop.
Maybe maybe maybe. try it. Sim it. what ever. then lets talk about it. BTW -- The Rs I used in the feedback was 0.1 Ohm in series with feedback resistor to ground, according to my notes. If you think this will make all the difference in the world, then lower it and change amps feedback R's as needed.
A simple R in series with speaker isnt the same effect as in the feedback loop, of course, and the thd wouldnt be reduced if not in the fb loop.
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Kgrlee, you can't intimidate me. I have a Hirata box in my lab. I have tested my previous designs in the past. I found what to avoid. However, I just might test a Blowtorch, just for the heck of it. We shall see.
Trying to find fault in a design from an armchair is not the most useful task you could assign yourself.
Trying to find fault in a design from an armchair is not the most useful task you could assign yourself.
Current drive + mechanical feedback by acceleration sounds like fun. 😉
But to avoid any fun I would go by an old and boring route: big drivers with big cone area and big coils in big stationary concrete enclosures. 😀
Why do you need to do this 0R1 resistor trick if you have Audyssey? Does the resistor trick provide stuff that Audyssey can't do?
That would be good JC. No intimidation or fault finding intended. Just wondering what the Hirata and Quan figures are for a supa dupa preamp as you've been at pains to tell us how important they are.
If I did want to find fault, I'd go on about Blind Listen... Shaddup Lee. JUST SHADDUP!!
Why do you think mr Keglee want to find "fault" ? A faulty part does not work at all.
It would love to compare a so expensive 'legendary' part against a 0 cent strait wire and a cheap very good preamp.
You use a very classical design, with selected parts and overkilling care in power supplies and manufacturing. You did-it like a stringed intrument maker, if we believe what you said, not like a modern electronic designer.
Value of the approach ? Value for money ?
Sure, as your preamp has no feedback, it will not measure as well as other solutions using feedback. You have chosen the "simple is beautiful" side. Did it sound much better ? highly different ?
Is your amp perfectly transparent, or did-it color the sound in an agreeable manner, like tubes can do ?
Is-it the miracle you pretend, or just the price witch make all the story?
In a blind test against less expensive preamp, will you crown your own work ?
In the same time, this test can be an interesting response to sociological questions.
The first is: Can a single household preamp deserves all this noise?
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I manufactured subwoofers with a position servo for a number of years. They were quite well received. The first generation with a Keith Johnson design. It used a variation on a metal detector to sense the position of the diaphragm. It worked well but we had to metallize the diaphragm to make it work. The second generation used a different servo I cooked up that did not require the driver mods. I also worked out a self calibration system for the servo centering. Its not too difficult even if all analog. We actually had an acceleration servo derived from back emf as well.
The first thing you learn with a true position servo is that the box drops out of the response (except for power requirements) and the response curve follows the displacement of the driver. You then must eq the system to get the desired response. You will also need a high pass filter or the driver will bang into the stops on real infrasonic stuff.
It would be possible to add electronic commutation so that a long overhung voice coil is driven only by the part inside the magnet. Sort of a class H speaker.
The loop delay on any servo really limits what you can do. No matter how light the diaphragm is, closing a servo above 1 KHz probably is doomed to failure.
If you are interested in making some I'll pass on the details. The system is quite complex. I don't think I want to get back into the subwoofer business again.
Mr. Marsh, I have tried it .. late 70's, better damping and less overall distortion just like you report .. unlike Wave who must not have been using Unobtainium resistors (joke Wave. Joke!)
But for a sealed box speaker, bass becomes less extended though better damped. Speakers with complex x-overs may show peaks & dips in the midrange. Ported speakers are more complicated but if Qts is too large, the Marsh resistor is like magic.
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Christophe, I'm not ignoring you. Your experiences are very like my Powered Integrated Super Sub tech. especially the bit about wider bandwidth at lower levels But if I acknowledge that, I must send my lawyers to see you about patent infringement like I've done with Wave. 😀
I tried optical methods and double coils too but the ACE stuff works so well that I abandoned the other stuff. Also tried current drive but again ACE is superior. See my original post on the subject. I'm sorry Wave didn't see any distortion reduction in his experiments. 😡
If I have novel input, it was incorporating ALL these technologies including linear & non-linear analogue & digital processing in a holistic manner.for Powered Integrated Super Stuff.
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Demian, Wharfedale looked at becoming European agents for a sub which just used a DC servo motor instead of a voice coil. Can't remember their name. The limits weren't at LF (until the cone surround bottomed out) ... but at HF (about 100Hz). 1000W easy cos it was an electric motor. Part of Powered Integrated Super Stuff was incorporating the stops electronically at little or no extra cost.
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Pheonix, alas, I'm now a (real) beach bum. I like this lifestyle but miss good music badly. I listen to a pair of original Active Diamonds which have soundly beaten the W***on W*** *****es (??) in several Blind Listening Tests in the previous millenium. But I'm dependent on charity for CDs ripped to evil digital. 😡
But if the question is what amp I like, my favourite was the Rotel RB5000, a 1000W/channel amp which graced our listening room for nearly 2 decades and was sometimes borrowed by the UK HiFi magazines to conduct their speaker reviews. It was chosen only after a long series of lesser Golden Pinnae amps did not meet the grade. It introduces no sound of its own under any load or signal.
2nd choice was the LEAK TLA-50, probably the best of the great valve LEAK amps and liked for the same reasons. Valve amps of a certain type can deliver MUCH more than their rated power under certain conditions.
Dunno what's good these days.
Which reminds me, what Levinson amps did you design in the 70's & 80's Mr. Curl?
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cool
OK. It seems to work on every speaker system... just more or less degree with no downside.
Regarding speaker cable series L... If we assume we are using our favorite lamp cord for speaker connects, the Ls will be typically 2-3uH for 10-15 ft. Many custom install -in wall wiring- and Home Theater systems are used for movies and music listening and the inductance can be much larger for those longer runs to all speakers. The Ls for these cable runs can get significant. I also notice that planar and ribbon drivers have a much lower L and are becoming popular and then we might reconsider the cable Ls again. It all depends on what cable and what speaker and how long.... not a blanket statement. Thx -RNMarsh
OK. It seems to work on every speaker system... just more or less degree with no downside.
Regarding speaker cable series L... If we assume we are using our favorite lamp cord for speaker connects, the Ls will be typically 2-3uH for 10-15 ft. Many custom install -in wall wiring- and Home Theater systems are used for movies and music listening and the inductance can be much larger for those longer runs to all speakers. The Ls for these cable runs can get significant. I also notice that planar and ribbon drivers have a much lower L and are becoming popular and then we might reconsider the cable Ls again. It all depends on what cable and what speaker and how long.... not a blanket statement. Thx -RNMarsh
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Wavebourn -- which Aud auto EQ model are you using. I got hold of their 6 dsp channel PRO model. It works very well for EQ'ing headphones as well... just need a probe mic. -RNMarsh
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They had a very good reputation for very good sound performance. Do you have any data that you can tell on how low the thd was on the servo woofer. I assume thats one of the reasons you made them servo. Thx-RNM
I do not think it measures relatively poorly, in case both input and output signals are used balanced. Then, up to some 1Vrms, it would measure quite perfect and there would be no higher harmonics. Harmonic or intermodulation distortion is definitely not an issue of the CTC Blowtorch design.
I know Parasound Halo JC-2 preamp, which is pretty good, and I would like to hear the CTC Blowtorch sometimes - which is highly unlikely.
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