I got my sacrificial lamb speaker today. The front of it isnt one carbon fiber piece like the pictures made it look. The dust cap is epoxyed in. So an accelerometer in the voice coil may be back on the table. Question is though: what kind of epoxy did they use? And is it worth the surgery?
Funny you should say that. Someone suggested a little while ago I should focus more on the enclosure first before I work on the MFB circuit. That and I've been going back and forth on whether I should just go DSP or not which would prompt a redesign there too. DIY problems, right? 🤪
Yes, work on the cabinet and driver choice!
Not to dismiss the motional or servo feedback loudspeaker concept for correcting speaker problems, but the fact is loudspeakers with proper DSP can achieve as much or more maximum SPL before subwoofer distortion becomes objectionable than arguably the best MFB.
Sweetchaos has compiled a list of various subwoofers and their output.
https://www.audiosciencereview.com/forum/index.php?threads/subwoofer-comparison.20494/
"How do you judge a subwoofer's performance?
Read the 'flowery' words on the manufacturer's website?
Listen to the personal opinion of owners who sing you songs of their subwoofer's performance, regardless of their actual performance?
Watch some random YouTuber talk about how "good" a subwoofer is, not realizing that he probably got the subwoofer for free, in order to do the review?
Read some ad-copy on some random website you found, that just lists the specifications and shows an affiliate link at the end?
None of the above! 😉
Instead, we need a consistent way to compare two subwoofers to each other.
That's why international standards like CEA-2010 exist."
What is CEA-2010?
CEA-2010 is an industry standard first published in 2006 (updated as CEA-2010-A in 2012) that specifies a method for measuring subwoofer's maximum SPL (before subwoofer distorts) at various frequencies.
https://docs.google.com/spreadsheet...fyBjaxK69dkXte6ZL6anVTW2_M/edit#gid=834598950
Velodyne Acoustics uses a specially developed accelerometer to "perfectly control diaphragm movement".
After 35 years in business they may be near the top of the servo-feedback field- certainly a bit farther along than most "DIY" examples.
The Velodyne Acoustics DD-18+ subwoofer at 7 cubic feet and 142 lb has a bit more low end potential but less upper potential than the lighter, smaller (4.5 CF, 142 lb) SVS SB16-Ultra.
The JTR Speakers Captivator RS1 (4.6 CF, 117 lb) has 7dB more level at 10Hz, and 8+dB at 125Hz- it would take two DD-18 occupying 3 times the space to equal one JTR RS1.
Considering the the JTR RS1 is going for about $3300 compared to $4775 for the DD-18, quite a bargain.
Art
Not to dismiss the motional or servo feedback loudspeaker concept for correcting speaker problems, but the fact is loudspeakers with proper DSP can achieve as much or more maximum SPL before subwoofer distortion becomes objectionable than arguably the best MFB.
Sweetchaos has compiled a list of various subwoofers and their output.
https://www.audiosciencereview.com/forum/index.php?threads/subwoofer-comparison.20494/
"How do you judge a subwoofer's performance?
Read the 'flowery' words on the manufacturer's website?
Listen to the personal opinion of owners who sing you songs of their subwoofer's performance, regardless of their actual performance?
Watch some random YouTuber talk about how "good" a subwoofer is, not realizing that he probably got the subwoofer for free, in order to do the review?
Read some ad-copy on some random website you found, that just lists the specifications and shows an affiliate link at the end?
None of the above! 😉
Instead, we need a consistent way to compare two subwoofers to each other.
That's why international standards like CEA-2010 exist."
What is CEA-2010?
CEA-2010 is an industry standard first published in 2006 (updated as CEA-2010-A in 2012) that specifies a method for measuring subwoofer's maximum SPL (before subwoofer distorts) at various frequencies.
https://docs.google.com/spreadsheet...fyBjaxK69dkXte6ZL6anVTW2_M/edit#gid=834598950
Velodyne Acoustics uses a specially developed accelerometer to "perfectly control diaphragm movement".
After 35 years in business they may be near the top of the servo-feedback field- certainly a bit farther along than most "DIY" examples.
The Velodyne Acoustics DD-18+ subwoofer at 7 cubic feet and 142 lb has a bit more low end potential but less upper potential than the lighter, smaller (4.5 CF, 142 lb) SVS SB16-Ultra.
The JTR Speakers Captivator RS1 (4.6 CF, 117 lb) has 7dB more level at 10Hz, and 8+dB at 125Hz- it would take two DD-18 occupying 3 times the space to equal one JTR RS1.
Considering the the JTR RS1 is going for about $3300 compared to $4775 for the DD-18, quite a bargain.
Art
Fortunately work is dead tonight so I've been reading! (Shhh don't tell them).
Something I've definitely seen as a reoccurring theme in that list, and frankly during a lot of this research into low end:
1) higher end typically does have some sort of DSP or at least much more granular control
2) the smaller you go, the more laws of physics you need to account for, and the more you need to compensate for them
As far as cabinet design goes, I was probably going to do a simple cylinder. The center would be a super dense material to segregate the two speaker sections (being mid/tweeter, and sub). A cylinder, apparently, has good acoustic properties (with the best being a sphere).
As far as DSP goes, I just haven't touched it because I'm not as boned up on digital as I am analog (weird right? It's usually the other way around). I'm also not a great coder. If I was going to do DSP I would probably either go with a Sharc project board or just design my own because the codec on it is meh.
1) DSP is used more and more in low-end as well as high end, it has become cheaper than passive or analog components, and offers far more control.
2) Can't get around Hofmann’s Iron Law:low, efficient, small, pick two.
Speakers with lower extension always have a sensitivity drop, as the efficiency of the woofer is proportional to the cabinet volume and the cube of its cutoff frequency.
Nothing simple about building a cylindrical speaker cabinet, a sphere harder yet. They look nice, if you like wieners or balls
Any cabinet with sufficiently rounded edges will work nearly as well as a sphere or cylinder regarding diffraction.
There isn't much advantage at all to internal shape regarding modal frequency and density, and when damped internally the shape is virtually inconsequential.
I've been personally been into loudspeaker enclosure design since the mid 1970's. I hadn't encountered "subwoofers" until 1978 or so, before DSP was commercially available.
By the early 1980s, codecs had been developed that made digital recorders compare with the best analog recorders.
In the 40 years since, the price has dropped and the quality increased to the point where cheap (compared to transducer cost) plug and play off the shelf "meh" reproduction quality surpasses anything in the speaker chain.
So the SP1632 is about 93db. The dayton is 10db below that. That's why I was going to stick with the high power chip in the design for the sub. Wouldn't have to change the design a lot, and it's a good piece of hardware so why change it?
That's a very good point. As long as the internals compensate correctly then it's all gravy.
If I DID go digital, I would go overkill because... well... DIY. 4 ess 9038 dacs, 2 per channel, differential signal. ADCs I would probably go overkill on as well. Sharc processors have sigma studio. That was the appeal. I also was eyeing a few open source FPGAs that are relatively inexpensive. From there I would just buffer it and drive it right to the chip. It's just implementing the design to get those things working together. Yes I'm very well aware of how powerful those chips are, but I would definitely be glued to this forum to figure out how I'm going to build the board.
Once you are dead, you're dead. :^)
By plug and play, I meant something like the minidsp that can implement FIR:
https://www.minidsp.com/products/minidsp-in-a-box/minidsp-flex-eight
Implementing the design to get the things working together that well is unlikely if you aren't "boned up on digital"..
But if you want to spend more time and money to DIY, go for it!
By plug and play, I meant something like the minidsp that can implement FIR:
https://www.minidsp.com/products/minidsp-in-a-box/minidsp-flex-eight
Implementing the design to get the things working together that well is unlikely if you aren't "boned up on digital"..
But if you want to spend more time and money to DIY, go for it!
sigh well... I am super stubborn
I originally looked into MiniDSP, but I figured, again, if I'm making it DIY I would like to use some parts with a little better specs.
The 2 biggest hurdles I would say to using sharc are:
1) Using the DSP dev environment. Sigmastudio is fairly straightforward, but not so much on CCES
2) Digital seems nowadays less about organizing timing signals (at least in the DSP sense) and more about coordinating chips between busses. That said, DSPs have A LOT of pins lol
That said, there IS a neat dev kit analog makes that has a great starting spot
https://www.analog.com/en/design-ce...valuation-boards-kits/sharc-audio-module.html
I'm just not sure that I would have the ports needed to add the ICs I want. Otherwise I would just use what's on that board to fill in the gaps
I originally looked into MiniDSP, but I figured, again, if I'm making it DIY I would like to use some parts with a little better specs.
The 2 biggest hurdles I would say to using sharc are:
1) Using the DSP dev environment. Sigmastudio is fairly straightforward, but not so much on CCES
2) Digital seems nowadays less about organizing timing signals (at least in the DSP sense) and more about coordinating chips between busses. That said, DSPs have A LOT of pins lol
That said, there IS a neat dev kit analog makes that has a great starting spot
https://www.analog.com/en/design-ce...valuation-boards-kits/sharc-audio-module.html
I'm just not sure that I would have the ports needed to add the ICs I want. Otherwise I would just use what's on that board to fill in the gaps
Hi, Sorry for the offtopic, but i have a pair of dayton epique 5.5 drivers in a speaker as a woofer. Currently im running them with the 2 coils serial. If my amp can give around 60w on 8 ohm but 90w on 4 ohm, and i want to raise the woofer sensitivity a bit, its better to use only 1 coil of it right?
Sensitivity of the speaker is not the same as amplifier power.
If you use only one coil of the two speakers, your sound output with the same input will halve so half sensitivity.
For max sensitivity with two given drivers, use them both.
The amp power for that will need to be sufficient for the setup, either parallel or in series.
What are the speaker impedances?
Jan
If you use only one coil of the two speakers, your sound output with the same input will halve so half sensitivity.
For max sensitivity with two given drivers, use them both.
The amp power for that will need to be sufficient for the setup, either parallel or in series.
What are the speaker impedances?
Jan
Yes i might expressed myself inproperly. So the 2 coils in serial have 8 ohm impedance. 1 coil is 4 ohm. 2 coils in parallel would be 2 ohms which is too much for my amp. This is why i thought that with the given amp, i would gain some volume with 1 coil only.
The amp doesn't 'push' power into the driver. The driver 'demands' power from the amp.
Each driver provides max sound output when it is driven to the max.
So you get max sound by driving both drivers to the max.
If you put them in series for 8 ohms, you need more voltage from the amp compared to parallel, 2 ohms, which would need a quarter of the voltage but four times the current.
Your amp probably doesn't handle 2 ohms well, and at 8 ohms provides 60W.
It depends on the speaker sensistivity (which is the sound output per watt amp power) how loud that amp can drive them.
If your drivers can handle it, you could use a Hypex or Purifi class D amp which can easily handle 2 ohms at a few 100W.
That'll teach those drivers ;-)
Jan
Each driver provides max sound output when it is driven to the max.
So you get max sound by driving both drivers to the max.
If you put them in series for 8 ohms, you need more voltage from the amp compared to parallel, 2 ohms, which would need a quarter of the voltage but four times the current.
Your amp probably doesn't handle 2 ohms well, and at 8 ohms provides 60W.
It depends on the speaker sensistivity (which is the sound output per watt amp power) how loud that amp can drive them.
If your drivers can handle it, you could use a Hypex or Purifi class D amp which can easily handle 2 ohms at a few 100W.
That'll teach those drivers ;-)
Jan