Someone mention a good cheap model of so-called parametric EQ..preferably sold locally at Australia to avoid shipping costs,etc.
Isaac and everyone who are familiar with Jaycar,
Does Jaycar sell "parametric" equalisers?
Isaac and everyone who are familiar with Jaycar,
Does Jaycar sell "parametric" equalisers?
I assume Behringer products are sold buy the pro audio shops there. If so, the DSP1100P soon to be replaced by the DSP1128P are great buys. In the US there is nothing cheaper than these, US$130 buys a DSP1100P
will the 'treated' foam surround of the BP1503 rot like normal foam surrounds or is it really durable and wont rot for 15+ years?
I'm totaly oblivious to pro gear here in Australia (or anywhere else for that matter 🙂 ) 'cause I always go the DIY route whenever practical. The only parametric equalizer I know of is in kit form and it is available from http://www.altronics.com.au (it was published in the July '96 issue of Silicon Chip magazine, btw).
The design has three sets of Q, frequency and cut/boost controls and each frequency band can be easily modified for subwoofer duty (the default design is for fullrange duty). The kit retails for AU$45.00 and it requires a +/-15V power supply, metal case etc. I'd say AU$100.00 should be enough to build a working prototype.
Regarding foam, with proper care the speaker can last for quite some time even for 15+ years. However, I doubt that you can resist the urge to build another monster subwoofer within a few years (or months?) after you complete this one 🙂
Isaac
The design has three sets of Q, frequency and cut/boost controls and each frequency band can be easily modified for subwoofer duty (the default design is for fullrange duty). The kit retails for AU$45.00 and it requires a +/-15V power supply, metal case etc. I'd say AU$100.00 should be enough to build a working prototype.
Regarding foam, with proper care the speaker can last for quite some time even for 15+ years. However, I doubt that you can resist the urge to build another monster subwoofer within a few years (or months?) after you complete this one 🙂
Isaac
Does anybody know how to design variable bass boost and variable phase control? I know many commercial amps use the variable boost and at least some of them also variable phase adjustment control but I have'nt seen any DIY approaches/shematics yet.
argo
argo
argo, try this link -- http://www.geofex.com/Article_Folders/EQs/paramet.htm
I could send you schematics and PCB artwork of a graphic equalizer and/or parametric equalizer, if you're interested.
As for information about variable phase control, I haven't seen any yet, sorry.
Isaac
I could send you schematics and PCB artwork of a graphic equalizer and/or parametric equalizer, if you're interested.
As for information about variable phase control, I haven't seen any yet, sorry.
Isaac
Is using 2 BP1503's in a sealed isobaric(push-pull) thingy like the sunfire, Krell, and M&K subwoofers a good idea? they say isobaric designs reduce distortion, etc,
Isaac thanks for the link and PCB artwork offering.
Hmm...the gyrators. Indeed I'm recalling now, that I have heard using something similar before. I just hoped there is some kind of simpler approach, than using simulated inductors.
As for variable phase control, I believe one is used in Apex Senior plate amp or at least that’s what they are claiming. They have schematic of x-over and amp on their web page but I haven’t had possibility to simulate this because I have trashed my old circuit simulator software.
argo
Hmm...the gyrators. Indeed I'm recalling now, that I have heard using something similar before. I just hoped there is some kind of simpler approach, than using simulated inductors.
As for variable phase control, I believe one is used in Apex Senior plate amp or at least that’s what they are claiming. They have schematic of x-over and amp on their web page but I haven’t had possibility to simulate this because I have trashed my old circuit simulator software.
argo
argo,
The simplest way, but the most expensive way at that, would be to use actual inductors 😀
Which circuit simulator do you use? I found PSPICE (I use Eval 8 version) to be very flexible, its Probe program is especially a powerful tool. But I use Circuit Maker also for its vast device library.
Do you happen to have a direct link to the apex amp schematics
Thanks 🙂
Isaac
The simplest way, but the most expensive way at that, would be to use actual inductors 😀
Which circuit simulator do you use? I found PSPICE (I use Eval 8 version) to be very flexible, its Probe program is especially a powerful tool. But I use Circuit Maker also for its vast device library.
Do you happen to have a direct link to the apex amp schematics
Thanks 🙂
Isaac
Yeah but you need to have a variable inductors!?
I have tried various demos like Circuit Maker, Protel etc. With their usage period or/and component quantity/board size limitations, I got tired of them taking up so much hard drive space, so I trashed most of them.
Apex Senior amp schematics I talked about is at: http://www.apexjr.com/Apexsenior.htm
argo
I have tried various demos like Circuit Maker, Protel etc. With their usage period or/and component quantity/board size limitations, I got tired of them taking up so much hard drive space, so I trashed most of them.
Apex Senior amp schematics I talked about is at: http://www.apexjr.com/Apexsenior.htm
argo
Which is why such equalizers with inductors would cost a mint 😀 Why not use gyrators?
Protel does require a big chunk of HDD space. But PSPICE and Circuit Maker are both well worth the required HDD real estate. Electronic Workbench is a baby compared to the other two -- always complaining about transient and convergence problems.
Thanks for the link! I might check it out now 🙂
Isaac
Protel does require a big chunk of HDD space. But PSPICE and Circuit Maker are both well worth the required HDD real estate. Electronic Workbench is a baby compared to the other two -- always complaining about transient and convergence problems.
Thanks for the link! I might check it out now 🙂
Isaac
gum
The Krell, M&K, etc, aren't isobaric configurations. And the drivers aren't wired push-pull. If they were push-pull they would cancel each other out since they share the same space.
The primary benefit to a true isobarioc config is the reduction in cabinet size do to the decrease in Vas.
Making a true isobaric config with 1503's would be difficult. They can't simply be bolted together in a 'clamshell' manner because the surrounds are to large. An adapter ring would be necessary to avoid having the surrounds rub together.
The Krell, M&K, etc, aren't isobaric configurations. And the drivers aren't wired push-pull. If they were push-pull they would cancel each other out since they share the same space.
The primary benefit to a true isobarioc config is the reduction in cabinet size do to the decrease in Vas.
Making a true isobaric config with 1503's would be difficult. They can't simply be bolted together in a 'clamshell' manner because the surrounds are to large. An adapter ring would be necessary to avoid having the surrounds rub together.
Isobaric=stupidity (in most cases)
If you absolutely must fit a woofer box into a really small space, like a car, and must have lots of power handling, then Isobaric might be a nice way to do it. But for large, open listening rooms, or even the occasional bedroom sub, I would not waste my money on more than 1 woofer per hole. I already tried that, and there was no real advantage to having push-pull woofers. It was easier to bottom them out. I would not recommend using isobaric woofers in anything but a sealed box to prevent the woofers from bottoming out so easily.
I'm not lucky enough to have a separate listening room. My listening room/home theater/office is in my bedroom. When I go away to college, that will be my dorm room. My BPD1001 subwoofer will only be 12 inches wide, so it can fit up against the side of my desk or between my bed and the wall, without needing to be an isobaric configuration.
If you absolutely must fit a woofer box into a really small space, like a car, and must have lots of power handling, then Isobaric might be a nice way to do it. But for large, open listening rooms, or even the occasional bedroom sub, I would not waste my money on more than 1 woofer per hole. I already tried that, and there was no real advantage to having push-pull woofers. It was easier to bottom them out. I would not recommend using isobaric woofers in anything but a sealed box to prevent the woofers from bottoming out so easily.
I'm not lucky enough to have a separate listening room. My listening room/home theater/office is in my bedroom. When I go away to college, that will be my dorm room. My BPD1001 subwoofer will only be 12 inches wide, so it can fit up against the side of my desk or between my bed and the wall, without needing to be an isobaric configuration.
Having a 2 driver cabinet with one woofer facing in and one facing out will result in the cancellation of the harmonics. But understand this isn't 'push-pull', nor is it isobaric
Also the current generation of woofers/subwoofers generate very little even order harmonics, so this type of mounting really isn't necessary.
Also the current generation of woofers/subwoofers generate very little even order harmonics, so this type of mounting really isn't necessary.
distortion
is it possible to buy an accelerator servo thingy (the one they use in velodyne) and install it in the woofer. Are there any threads or web pages that show you how to do this?
is it possible to buy an accelerator servo thingy (the one they use in velodyne) and install it in the woofer. Are there any threads or web pages that show you how to do this?
It's probably an easy circuit to implement, though I haven't thought about it much simply because there's a better solution -- build better subs with *quality* drivers... more of these would be better of course 😀
I'd set aside such critical thinking for now 🙂 and proceed with building your BP (or Tempest?) subwoofer then compare it with a Velodyne. It is highly unlikely that you'll feel the need for a current limiter after the comparison. 🙂
Isaac
I'd set aside such critical thinking for now 🙂 and proceed with building your BP (or Tempest?) subwoofer then compare it with a Velodyne. It is highly unlikely that you'll feel the need for a current limiter after the comparison. 🙂
Isaac
What the Buzz?
Why would you want to put a current limiter on a subwoofer with as much raw horsepower as the BPD xx03 series? The velodyne uses paper drivers that probably cost them $40 apiece, so they need current limiters to keep their amps from melting the voice coils right off their formers.
Why would you want to put a current limiter on a subwoofer with as much raw horsepower as the BPD xx03 series? The velodyne uses paper drivers that probably cost them $40 apiece, so they need current limiters to keep their amps from melting the voice coils right off their formers.
The two common ways to approach servo loops are to use:
1) A piezo element
2) An accelerometer
The piezos have ferocious phase shift, so you'll need to compensate for that, but after that it's pretty straight forward.
The accelerometer chips are available here and there (Digikey has them), but they're damned expensive--about $15-20 per chip. (Compared to piezos for less than a dollar.)
In either case, generally you mount them under the dust cap/center dome.
Phenomenal results can be had from a servo system. Bad drivers sound good. Good drivers sound better. High quality drivers sound magnificent. I've heard several servo (not to be confused with 'feed forward' systems) systems over the years and they all tend to leave you shaking your head, not knowing that subs could possibly sound that deep, fast, and tight.
I've got an optical method that I'm going to try once I can shake free a few hours. I will eventually report on this if I can just get a few more things off my to-do list, as it's a high priority item for me.
Grey
1) A piezo element
2) An accelerometer
The piezos have ferocious phase shift, so you'll need to compensate for that, but after that it's pretty straight forward.
The accelerometer chips are available here and there (Digikey has them), but they're damned expensive--about $15-20 per chip. (Compared to piezos for less than a dollar.)
In either case, generally you mount them under the dust cap/center dome.
Phenomenal results can be had from a servo system. Bad drivers sound good. Good drivers sound better. High quality drivers sound magnificent. I've heard several servo (not to be confused with 'feed forward' systems) systems over the years and they all tend to leave you shaking your head, not knowing that subs could possibly sound that deep, fast, and tight.
I've got an optical method that I'm going to try once I can shake free a few hours. I will eventually report on this if I can just get a few more things off my to-do list, as it's a high priority item for me.
Grey
I think theres a misunderstanding. The accelerator thingy is not a so-called 'current limiter'. Its a chip that measures the motion of the speaker cone several thousand times a second. The data is then carried into a processor where it is compared to the original input signal. Any distortion in movement of the cone is corrected -therefore making it sound just better.
The problem is It doesn't sound possible for a ordinary home user
The problem is It doesn't sound possible for a ordinary home user
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