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Any interest in an ASR community speaker project?

dwkdnvr

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So, we have 3 types of responses in this thread
1) people suggesting a lowest-common denominator cheap project in an attempt to draw a bunch of people into giving it a try. This results in yet another 5/6" 2-way
2) people suggesting a relatively conventional but high-end build (that in most cases they don't seem to be able to do themselves) that prices out pretty much everyone, but tries to show how DIY can be high-value compared to commercial "high end" speakers
3) people advocating for an all-out assault on the state of the art generally using unconventional ideas or techniques, at least some of which seem more like research projects than proven methods.

It's not surprising that these types of initiatives don't end up making much progress. Ultimately everyone wants to do their own thing, and nobody is going to put in significant effort or $$$ towards building someone else's idea.
 

KSTR

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It's not surprising that these types of initiatives don't end up making much progress.
That's pretty much it, unless somebody goes ahead, designs and builds something, then sellling cabinet plans and XO kits, and a bunch of peoble organizing group buys for the drivers. I basically see this thread as some form of initial brainstorming...
 
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That's pretty much it, unless somebody goes ahead, designs and builds something, then sellling cabinet plans and XO kits, and a bunch of peoble organizing group buys for the drivers. I basically see this thread as some form of initial brainstorming...

This just isn't a very DIY focussed forum I don't think, compared to others I frequent. People seem to have missed the point of this exercise that a single prototype be sent around and worked on by several people. A small speaker enables collaboration in a way that a large speaker doesn't. The end result is not really that important.
 

HooStat

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Is it possible to have one project with several branches? Start with a single cabinet and 2 drivers. Versions might include inexpensive drivers, moderate drivers, very expensive drivers, passive cross-overs, and active cross-overs. And perhaps sealed and ported variations.
 
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Is it possible to have one project with several branches? Start with a single cabinet and 2 drivers. Versions might include inexpensive drivers, moderate drivers, very expensive drivers, passive cross-overs, and active cross-overs. And perhaps sealed and ported variations.
I am very interested in making the ultimate 4 inch speaker. But I'm also looking at making a 6 inch 2 way with totally off the shelf parts and very good off axis with an off the shelf cabinet.

The audio quality result is only part of the challenge with design. Making something to a budget or with easily available and easily fabricated parts is way more interesting to me than some SOTA project.

I'm going to pursue what interests me and see if anyone wants to help out.
 

KSTR

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... ultimate 4 inch speaker ...
Tang Band W4-1320 is one of my favorites for a small "mini-monitor" with stunning quality on vocals and if bedroom levels are all that's needed you can have some low bass (40Hz-ish) from it, too. Active of course for best results but since it's only one channel with a bit of EQ the effort would remain reasonable.
Then again, the cheapest 12" coax I know of is only 1.5x the price of that 4"...
 

briskly

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The third option would be a two way with a waveguide. I'm thinking the Seas DXT or the Wavecor unit would be the best two candidates - I'm not aware of any others.
Why not use a particular off-the-shelf waveguide extension or one of the custom designs here? As far as an easy directivity match, those tweeters are most suited for 4" drivers, maybe a particular 5" unit here or there.
 

bogart

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This just isn't a very DIY focussed forum I don't think, compared to others I frequent. People seem to have missed the point of this exercise that a single prototype be sent around and worked on by several people. A small speaker enables collaboration in a way that a large speaker doesn't. The end result is not really that important.

May I suggest editing the original post in case people are still reading it before jumping in? While I have been reading with interest, I actually missed that this was the *central* idea of the project.

Perhaps calling out that the idea is "to collaborate on the design and production of a single prototype for evaluation and iteration with the thought of creating a confirmed and verified design for others to build" vs. all of us design and build the same thing in parallel? I have less to offer in this situation, but substantially more to learn by observing design conversations, etc.

Perhaps I can add some other thoughts on selection criteria with that in mind:
  • Are there interesting questions to answer for a single speaker that Klippel NFS testing (vs. a well-modeled and well-understood physics) would answer?
  • Are there unique skills in the group that would lend to collaboration (e.g. "I have a CNC cutter that can create some exotic baffle geometry that we're all dying to test")

If the goal isn't "baby's first two-way speaker" and we think that testing it makes the project more interesting, a different problem statement might be more interesting. For my part, when things are back to normal, a makerspace with CNC capabilities would be fun to try out - if someone has home equipment and a willingness to be a principal on the project would be no less fascinating as a spectator.
 
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May I suggest editing the original post in case people are still reading it before jumping in? While I have been reading with interest, I actually missed that this was the *central* idea of the project.

Perhaps calling out that the idea is "to collaborate on the design and production of a single prototype for evaluation and iteration with the thought of creating a confirmed and verified design for others to build" vs. all of us design and build the same thing in parallel? I have less to offer in this situation, but substantially more to learn by observing design conversations, etc.

Perhaps I can add some other thoughts on selection criteria with that in mind:
  • Are there interesting questions to answer for a single speaker that Klippel NFS testing (vs. a well-modeled and well-understood physics) would answer?
  • Are there unique skills in the group that would lend to collaboration (e.g. "I have a CNC cutter that can create some exotic baffle geometry that we're all dying to test")

If the goal isn't "baby's first two-way speaker" and we think that testing it makes the project more interesting, a different problem statement might be more interesting. For my part, when things are back to normal, a makerspace with CNC capabilities would be fun to try out - if someone has home equipment and a willingness to be a principal on the project would be no less fascinating as a spectator.
Thanks for your perspective. I think a simple passive speaker is the way to go here but that doesn't make it uninteresting. Making a 4" speaker with perfectionist performance and high output is one such challenge. Making an 8" two way with great off axis performance is another.
 
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Tang Band W4-1320 is one of my favorites for a small "mini-monitor" with stunning quality on vocals and if bedroom levels are all that's needed you can have some low bass (40Hz-ish) from it, too. Active of course for best results but since it's only one channel with a bit of EQ the effort would remain reasonable.
Then again, the cheapest 12" coax I know of is only 1.5x the price of that 4"...
I've never seriously looked at PA coaxes, but maybe there is something interesting there.
 

jhaider

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I'd be in for a large (12"/15") coax, could be based on one of the more affordable PA specimen, something like a Celestion FTX1225 (though there are even cheaper models around).

Instead of reinventing the wheel, perhaps support this project:
https://www.diysoundgroup.com/home-theater-speaker-kits/home-theater-series/vortex.html

It looks like they put some effort into refining the coax for home audio use. You could always ditch the passive crossover and go active with a DSP controller + amps, or plate amp.
 
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TimW

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If you are interested in contributing something other than opinions, let me know what you like doing and are good at. I know for a fact that we have the tools between us to come up with a really interesting and refined design. Can you cut a baffle? Can you make a PCB? Can you donate parts? Can you make accurate measurements? Etc.
I am a drafter by trade so I can make 3D models and 2D drawings. And I know how to take accurate measurements. I also have experience with 3D printing but have never used CAM software for CNC. I live close enough to Amir to hand things off to him as well.

The perfectionist 4" two way would be interesting to me. But that's because I would use it with my 8" subwoofers. The wide directivity 6" is mildly interesting. A good 3 way for a reasonable price seems less common in the DIY space. You could probably get excellent results with a $15 tweeter like the Peerless in the AAM, a small midrange driver for around $30 or less, and a woofer for $45 or so. It would probably require a complex and expensive crossover that takes a lot of effort to design. It seems to me like commercial offerings in the affordable range usually skimp on the crossover, so making a design with an advanced crossover and affordable drivers is interesting to me.
 
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I am a drafter by trade so I can make 3D models and 2D drawings. And I know how to take accurate measurements. I also have experience with 3D printing but have never used CAM software for CNC. I live close enough to Amir to hand things off to him as well.

The perfectionist 4" two way would be interesting to me. But that's because I would use it with my 8" subwoofers. The wide directivity 6" is mildly interesting. A good 3 way for a reasonable price seems less common in the DIY space. You could probably get excellent results with a $15 tweeter like the Peerless in the AAM, a small midrange driver for around $30 or less, and a woofer for $45 or so. It would probably require a complex and expensive crossover that takes a lot of effort to design. It seems to me like commercial offerings in the affordable range usually skimp on the crossover, so making a design with an advanced crossover and affordable drivers is interesting to me.

Yeah I'm toying with a few designs. A 6+1 with waveguide using the wavecor tweeter is not exciting but it is a great speaker for a lot of people. A 5" 3 way is a very unusual idea, and could be made very compact. A really affordable 'classic' 3 way is in some ways not that exciting, but I don't know of many designs of this format which are designed using full polar measurements and spinorama graphs (there probably are some). This would be an interesting place to use one of those dayton dsp amps 2x50W since crossover cost (and size) becomes an issue in small 3 ways.

I'm currently finishing a project which uses an off the shelf tweeter and off the shelf waveguide, mated via 3d printed adapter. Unfortunately this design uses a woofer which is a little tricky to source.

I'm glad to see interest in a small speaker which is specifically designed for subwoofer use. Most small speakers cheap out on parts and don't offer much SPL, and if you can design something good, you have the potential for a very versatile system.

This evening I tried modelling some MTM where the "T" were either vertically oriented ribbons or small arrays (2-3 drivers) of tiny tweeters. My thinking was that the DI could be made smooth if the tweeter had the same proportions as the woofer array (both vertical.) After some modelling I'm not sure it would work, but the idea of making an MTM which actually does work is interesting to me as well.
 

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I am very interested in making the ultimate 4 inch speaker. But I'm also looking at making a 6 inch 2 way with totally off the shelf parts and very good off axis with an off the shelf cabinet.

The audio quality result is only part of the challenge with design. Making something to a budget or with easily available and easily fabricated parts is way more interesting to me than some SOTA project.

I'm going to pursue what interests me and see if anyone wants to help out.
This project appeals to the community aspect of what draws me to ASR, but my concern is that a substandard / not state of the art product would undermine the overall ethos of what this site is about. Developing something that doesn't test very, very well, but meets a preconceived size specification, could be fodder for others to attempt to impugn the other work done here.

That said, if this project grows legs, I would happily contribute funding (with no technical abilities to contribute) as well as buy a pair of the speakers.
 
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Thanks everyone for their input.

I've been exploring the new DSP amplifier boards offered by parts express mentioned previously. These are really nifty products:
  • There is a 2x50W module with DSP
  • There is a 1x100W module with DSP
  • There is a 1x100W module without DSP which can plug into the 2x50W module, allowing you to do a 3 way system 100x50x50W
  • There is an outboard preamp/dsp module which can be combined with other amplifier modules, such as an IcePower 125x2 or 50x2, or whatever else is desired if higher quality amplification is needed.
I have asked a few people if they are willing to characterize these modules. I doubt they have state of the art audio quality, but if the power is reasonable, the addition of DSP should enable seriously high audio quality in a 2 or 3 way design.

I think the best application for these modules would be in a 3 way design. Why? A 3 way passive design has a lot of crossover components, which is a pain in the ass to build, measure and simulate. If you use quality passive components, the cost is not insignificant, especially if you're using a big woofer and midrange, requiring lots of inductance and capacitance. This is where an active implementation shines.

The cost of these DSP units? For a 3 way, stereo system, including 5A/24V power supplies, $221 USD. You can easily spend that much on crossover components for a relatively simple crossover. This is for a 50x50x100W system (both speakers.) Connections would be 1 audio connection and one DC jack on the back of the speaker.

The use of DSP simplifies design of a 3 way immensely - matching driver sensitivity is no longer a driving concern, you can boost bass and use a smaller enclosure. Low order filters, which help blend directivity characteristics, are much easier to implement due to delay.

The great advantage of a good stand mount 3 way is a very dynamic sound coming from a big cone - 8 or 10". There is an 8" and a 10" driver I am looking at. With DSP in a sealed enclosure of around .6 cubic foot (17L), they can do around 92db/2M at 40hz, and 100db at 200hz+.

For the midrange and tweeter, costs can be significantly reduced. Finding a 3" midrange with low distortion from 400-3300hz is pretty easy, and finding a well behaved tweeter above 3300hz is child's play. If it were me, I'd use nice drivers I already have (sb26STC and Peerless ne123) which retail for a combined $90USD, but part of what you pay for with nice drivers is ease of use with simple passive filters. If you have unlimited EQ bands, you can do better with, for example, a Vifa TC9/Peerless BC25 (about 30 dollars combined.)

This puts driver and amp/dsp cost at around $240 for one speaker. This is pretty damn cheap. You could upgrad to SB acoustics drivers, for example:
SB23NBAC - $109
SB12MNRX - $51
SB21RDC - $46
Or about $316 for a speaker, but I'm not sure that with DSP, you get anything over the cheaper drivers in this case - perhaps a bit more SPL capability in the lower midrange.

What is the sound quality here? Well ASR has not measured many 3 way speakers, but a good 3 way with small (~3") midrange has very wide dispersion in the lower treble, with smooth directivity characteristics. This format of speaker has become somewhat uncommon due to size, but again DIY shines here - making a big speaker isn't that much more difficult or expensive than building a small one. In some ways it's easier.

Anyway - I'd be interested to read everyone's thoughts on this approach. I am going to give some more thought to cabinets next.
 

Thomas savage

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If we could agree on some simple concepts..,

A bookshelf, easy to send via post .

Active DSP , some sort of room correction and subwoofer output

It's the ASR mark 1 , keep it simple , cheap as to encourage participation. If it's successful we can do a Mark 2 but let's not defeat ourselves by wanting too much first time around .

Personally I'd like to see the form factor be something other than just a box but maybe that's too much to ask for this one.
 

HooStat

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perhaps a bit more SPL capability in the lower midrange
I like this idea. I think it makes sense, at least for my interest. It sounds like a modern (DSP) alternative to the Philharmonic BMR (stand mounted 3-way).

I don't know how good the amps are, but my only thought is that a more sensitive set of drivers might keep the speakers within the optimum (low distortion) operating output of the amps.
 

TimW

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Thanks everyone for their input.

I've been exploring the new DSP amplifier boards offered by parts express mentioned previously. These are really nifty products:
  • There is a 2x50W module with DSP
  • There is a 1x100W module with DSP
  • There is a 1x100W module without DSP which can plug into the 2x50W module, allowing you to do a 3 way system 100x50x50W
  • There is an outboard preamp/dsp module which can be combined with other amplifier modules, such as an IcePower 125x2 or 50x2, or whatever else is desired if higher quality amplification is needed.
I have asked a few people if they are willing to characterize these modules. I doubt they have state of the art audio quality, but if the power is reasonable, the addition of DSP should enable seriously high audio quality in a 2 or 3 way design.

I think the best application for these modules would be in a 3 way design. Why? A 3 way passive design has a lot of crossover components, which is a pain in the ass to build, measure and simulate. If you use quality passive components, the cost is not insignificant, especially if you're using a big woofer and midrange, requiring lots of inductance and capacitance. This is where an active implementation shines.

The cost of these DSP units? For a 3 way, stereo system, including 5A/24V power supplies, $221 USD. You can easily spend that much on crossover components for a relatively simple crossover. This is for a 50x50x100W system (both speakers.) Connections would be 1 audio connection and one DC jack on the back of the speaker.

The use of DSP simplifies design of a 3 way immensely - matching driver sensitivity is no longer a driving concern, you can boost bass and use a smaller enclosure. Low order filters, which help blend directivity characteristics, are much easier to implement due to delay.

The great advantage of a good stand mount 3 way is a very dynamic sound coming from a big cone - 8 or 10". There is an 8" and a 10" driver I am looking at. With DSP in a sealed enclosure of around .6 cubic foot (17L), they can do around 92db/2M at 40hz, and 100db at 200hz+.

For the midrange and tweeter, costs can be significantly reduced. Finding a 3" midrange with low distortion from 400-3300hz is pretty easy, and finding a well behaved tweeter above 3300hz is child's play. If it were me, I'd use nice drivers I already have (sb26STC and Peerless ne123) which retail for a combined $90USD, but part of what you pay for with nice drivers is ease of use with simple passive filters. If you have unlimited EQ bands, you can do better with, for example, a Vifa TC9/Peerless BC25 (about 30 dollars combined.)

This puts driver and amp/dsp cost at around $240 for one speaker. This is pretty damn cheap. You could upgrad to SB acoustics drivers, for example:
SB23NBAC - $109
SB12MNRX - $51
SB21RDC - $46
Or about $316 for a speaker, but I'm not sure that with DSP, you get anything over the cheaper drivers in this case - perhaps a bit more SPL capability in the lower midrange.

What is the sound quality here? Well ASR has not measured many 3 way speakers, but a good 3 way with small (~3") midrange has very wide dispersion in the lower treble, with smooth directivity characteristics. This format of speaker has become somewhat uncommon due to size, but again DIY shines here - making a big speaker isn't that much more difficult or expensive than building a small one. In some ways it's easier.

Anyway - I'd be interested to read everyone's thoughts on this approach. I am going to give some more thought to cabinets next.
I have used these Sure Electronics or WONDOM brand amplifiers in many projects. Parts Express has them re-branded with red PCBs and makes nicer user manuals for them. I bought mine before Parts Express started selling these but I would prefer to source the boards from them since it is the same price and comes from their US warehouse rather than China direct. I have also used their Bluetooth equipped amp boards but I would not recommend them due to nasty ground loop noises and DC offset when using the supplied volume pot.
20190927_070001.jpg

20190726_175103.jpg

I turned this old General Electric speaker into a battery powered bluetooth speaker using the 1x100w amp with DSP (equivalent to the DSPB-100) and the 1x100w amp without DSP (WONDOM AA-AB31184). As you can see they are mounted on the KAB-AB L-type Aluminum Bracket using the
PC Board M3 Standoff Kit. I have used the 1x100w and 2x50w amps without DSP for a few different bluetooth speaker projects and have been quite satisfied. I would bet that their measured performance is mediocre but they sound perfectly adequate to me. Thankfully there was no ground loop issue when powering both amplifier boards from the same power supply. The gain of these two amps is different but once I had the volume properly set, there didn't seem to be any audible difference between the amps while I was deciding which to use for woofer and which for tweeter. Noise levels weren't super low but they were about on par with my LSR305's, although I was using the not so efficient Peerless DX20BF00-04. After this project I realized it would have made more sense to just use the 2x50w amp with DSP for a 2-way speaker.
20191204_184025.jpg

20200601_232455.jpg

20200601_232542.jpg

This is an old XAM 4E speaker that I am turning into a self power speaker with built in phono preamp. I'm using the 2x50w amp with DSP for this one with the same Peerless tweeter and the Dayton Audio DC160-4.

All of these DSP units from Sure Electronics use the ADAU1701 chip which is the same part used in the standard miniDSP 2x4. I wouldn't call the miniDSP 2x4 simple to use, but the Sure Electronics units are even less user friendly imo. First of all they require the Dayton Audio DSPB-ICP1 for programming, which is an added cost. But more annoyingly they use the SigmaStudio software for programming which is not intuitive. Now, once you have learned to use the software and have created the perfect crossover, it is easy to save that configuration and share it with others. However just getting the program to recognize the DSP board and getting the configuration properly synced can be a pita. I wouldn't consider this a deal breaker but someone will have to create a detailed guide if this project is meant to be shared with a larger audience.

Also the Dayton Audio DSPB-K is interesting but when used with the Dayton Audio DSPB-KE i/o board it only gives you 3 outputs. I'm not sure if the DSPB-K board is inherently limited to 3 outputs but it's a shame the connection board designed for it is limited. When you consider the price of these two boards together along with the price of the DSPB-ICP1 programming board, and keep in mind that it only has 3 outputs, I would prefer to use the miniDSP 2x4 Kit. And I would not be surprised if the miniDSP has better measured performance when you look at the supporting circuitry around the ADAU1701. The DSPB-250 is definitely the sweet spot when it comes to price vs features seeing as you're getting a 2x50w amplifier along with two more outputs from a 3.5mm jack. Pairing that with the 1x100w amp without DSP woud make a lot of sense for a 3-way speaker. And then there's still an extra output for a subwoofer if you want it, although I think it would make more sense to use a preamplifier or processor with subwoofer outputs before the speakers.
 
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