Servo Subwoofers
04-01-2005, 02:15 PM
#11
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Originally posted by SUX 2BU:
110 DB of in-car bass is pretty limited; it is. That's hardly louder than raised-voice talking. If you are only getting 110 dB, you aren't getting much impact IMO.
110 DB of in-car bass is pretty limited; it is. That's hardly louder than raised-voice talking. If you are only getting 110 dB, you aren't getting much impact IMO.
Considering that a pnumatic hammer at 2m registers 100dB...you must talk pretty loud to begin with!
Not to mention that I have measured my own UCL (uncomfortable level) with speach is 105 dB SPL (110dB HL)...and I have normal hearing.
04-01-2005, 03:44 PM
#12
The weight of the measurement means alot...
110db of A-weighted subbass is quite loud.. un-weighted its not...
You can buy accelerometers and Iam pretty sure Ive seen plans for a compairator circuit.. Iam sure it wouldnt be that hard for an enthusiest to turn any sub into a servo-feedback sub... of course if you already know that your cone travil is linear there isnt much point.... [img]graemlins/dunno.gif[/img]
110db of A-weighted subbass is quite loud.. un-weighted its not...
You can buy accelerometers and Iam pretty sure Ive seen plans for a compairator circuit.. Iam sure it wouldnt be that hard for an enthusiest to turn any sub into a servo-feedback sub... of course if you already know that your cone travil is linear there isnt much point.... [img]graemlins/dunno.gif[/img]
04-01-2005, 06:12 PM
#14
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Originally posted by Haunz:
The weight of the measurement means alot...
110db of A-weighted subbass is quite loud.. un-weighted its not...
The weight of the measurement means alot...
110db of A-weighted subbass is quite loud.. un-weighted its not...
Originally posted by Haunz:
You can buy accelerometers and Iam pretty sure Ive seen plans for a compairator circuit.. Iam sure it wouldnt be that hard for an enthusiest to turn any sub into a servo-feedback sub... of course if you already know that your cone travil is linear there isnt much point.... [img]graemlins/dunno.gif[/img]
You can buy accelerometers and Iam pretty sure Ive seen plans for a compairator circuit.. Iam sure it wouldnt be that hard for an enthusiest to turn any sub into a servo-feedback sub... of course if you already know that your cone travil is linear there isnt much point.... [img]graemlins/dunno.gif[/img]
Want to explain the last point about linear cone travel?
04-01-2005, 07:56 PM
#15
Originally posted by Coffeyman:
...but does anyone know if servo motor subs are legal in db drag? i though i heard something about them being illegal pecause they are power assisted subs or something like that?
if you can't use them for db drag...what's the point!
...but does anyone know if servo motor subs are legal in db drag? i though i heard something about them being illegal pecause they are power assisted subs or something like that?
if you can't use them for db drag...what's the point!
btw.. I have a cyclone.. haven't even powered it up yet. They need an active crossover and like 200w at 8Ohms. Neither of which I have right now
I will get it though... and soon. I'm just worried that I won't set it up properly because I'm not an SQ guy.
04-02-2005, 06:33 PM
#16
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Originally posted by JRace:
</font><blockquote>quote:</font><hr />Originally posted by Audissy1:
Also, in terms of output, the circuitry did limit output to 110dB according to the manual.
All setup issues aside, they were one of my favorite sounding subs to date!
Bryan
</font><blockquote>quote:</font><hr />Originally posted by Audissy1:
Also, in terms of output, the circuitry did limit output to 110dB according to the manual.
All setup issues aside, they were one of my favorite sounding subs to date!
Bryan
IMO anyone who thinks they need more that 110dB SPL from a sub needs to give the head a shake!
(Or give me a call at the Vernon Hearing Aid Clinic) </font>[/QUOTE]Well I guess it's a personal preference thing (like everything regarding audio reproduction). I felt that the 2 Velodyne's were more than enough. I also heard a friend's install with a single Velodyne 12 and it was also enough output for my tastes.
Bryan
04-03-2005, 09:47 AM
#17
Originally posted by JRace:
Yous got that backwards...a-weighted has less emphasis on lows, c-weighted is more even and thus your low freq registers as louder.
Want to explain the last point about linear cone travel?
Yous got that backwards...a-weighted has less emphasis on lows, c-weighted is more even and thus your low freq registers as louder.
Want to explain the last point about linear cone travel?
monitoring cone travil when you already know its linear would be a little redundent..
04-03-2005, 08:02 PM
#18
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Just to clarify, two very different concepts when you are talking about "servo subwoofers":
1) servo-feedback, which uses technology to electricly "mic" the cone motion to compare it to the original waveform, for accurate reproduction assurance (damn... why not servo-feedback mids and tweets?
).
2) servo-motor subwoofers, which use DC servo motors from the machine world to power a subwoofer diapragm... usually using a rotary-to-linear motion converter to drive a pair of cones (such as Servo Drive's offerings), although Phoenix Gold produced the direct-drive rotary Cyclone in the early 90's for a short while. If nothing else, very interesting
Servo-feedback is real interesting, at least in concept.
I've always personally had my doubts about the concept though... for one, it's simply expensive, all those extra electronics. And it adds complexity, which isn't fun for the tweaker, or often for reliability.
But more fundamentally - what is servo-feedback trying to accomplish? Straightening out innaccuracies, right?
But what's the cause of the innaccuracies?
Nonlinearities in the driver? How is servo-feedback going to adjust for a BL curve shape that isn't flat, and how about one that is most likely not perfectly centered? How about a suspension that isn't linear - and probably has a different Kms curve on the out-stroke compared to the in-stroke?
Distortions of this sort aren't really the sort of things that can even be detected, by comparing the input waveform to the output waveform... and it's been claimed that intermodulation distortions (distortions created by those nonlinearities) are the most audible distortion products.
Hence, my doubt.
I have no doubt that the Velodyne subs are great SQ subs. But is it because of the servo-feedback system? Or just because they are nice subs?
Another point bearing relevance...
The lower you go in frequency, the less capable anyone's ears are in perceiving distortions and other anomolies.
In fact, most people can't hear distortion approaching 10% in the bottom octave, while they can pick up fractions of a percentage of distortion in the upper ranges.
Again, this makes me wonder... does servo feedback work? Or do we want to believe it works, because it sounds like a cool idea - therefore it does?
...or ...maybe that "they are just really nice subs" thing again?
After all, I have no doubt they sound nice.
1) servo-feedback, which uses technology to electricly "mic" the cone motion to compare it to the original waveform, for accurate reproduction assurance (damn... why not servo-feedback mids and tweets?
). 2) servo-motor subwoofers, which use DC servo motors from the machine world to power a subwoofer diapragm... usually using a rotary-to-linear motion converter to drive a pair of cones (such as Servo Drive's offerings), although Phoenix Gold produced the direct-drive rotary Cyclone in the early 90's for a short while. If nothing else, very interesting
Servo-feedback is real interesting, at least in concept.
I've always personally had my doubts about the concept though... for one, it's simply expensive, all those extra electronics. And it adds complexity, which isn't fun for the tweaker, or often for reliability.
But more fundamentally - what is servo-feedback trying to accomplish? Straightening out innaccuracies, right?
But what's the cause of the innaccuracies?
Nonlinearities in the driver? How is servo-feedback going to adjust for a BL curve shape that isn't flat, and how about one that is most likely not perfectly centered? How about a suspension that isn't linear - and probably has a different Kms curve on the out-stroke compared to the in-stroke?
Distortions of this sort aren't really the sort of things that can even be detected, by comparing the input waveform to the output waveform... and it's been claimed that intermodulation distortions (distortions created by those nonlinearities) are the most audible distortion products.
Hence, my doubt.
I have no doubt that the Velodyne subs are great SQ subs. But is it because of the servo-feedback system? Or just because they are nice subs?
Another point bearing relevance...
The lower you go in frequency, the less capable anyone's ears are in perceiving distortions and other anomolies.
In fact, most people can't hear distortion approaching 10% in the bottom octave, while they can pick up fractions of a percentage of distortion in the upper ranges.
Again, this makes me wonder... does servo feedback work? Or do we want to believe it works, because it sounds like a cool idea - therefore it does?
...or ...maybe that "they are just really nice subs" thing again?
After all, I have no doubt they sound nice.
04-03-2005, 09:34 PM
#19
A servo feedback will simply limit a woofers output to its linear range.. I guess if the woofer is a total pile and isnt linear at all you are SOL no matter what you do..
You have a good point though, same one I was trying to make... if you have a good quality sub in the proper hands you dont really need such a circuit...
ie. If a velodyne user simply limited the input power on their own, they would still be all good..
You have a good point though, same one I was trying to make... if you have a good quality sub in the proper hands you dont really need such a circuit...
ie. If a velodyne user simply limited the input power on their own, they would still be all good..
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