Any interest in an ASR community speaker project?

[Vij]

Doh!. Correct, but I was more thinking cu.ft rather that ways.

I would be happy to try make a cheaper version of M106. Given that this will be my first DIY speaker, I will not be able to contribute significantly except in the way of questions. Was hoping to make an active version but not sure how to select value amp and dsp modules.

 

[McFly]

If it was agreed - perhaps by poll in another thread - that that was the design scope, then ASR could move onto driver selection. But there doesn't seem to be much of a DIY presence at this forum yet, which I thought there would've been.

 

[CASE2112]

There are a lot of great DIY designs out there already. Few of them are active. Many hear at ASR tout the benifits of active designs and point out that it is the future of speaker design. I think it would be much more interesting to create an active design.

I agree with TimW. Active design is the future, at least for a large percentage of consumers. With about $100 worth of parts, a remarkable design could be created that could compete with others on a mid-range price scale - $400-$600. I appreciate desktop solutions, something less than 11" in height would be a great target to aim for in this project.

 

[Evozero]

Hi All,
I think this forum is exciting and feels like a breath of fresh air, after reading 20 pages I would happily follow and build this project.
Design consensus appears the most difficult issue, here are my thoughts as a relative novice speakers builder.
Cabinet construction and lack of tools is the biggest hurdle, especially the baffle.
Having a lightweight mould / baffle / waveguide that could be shipped / printed and filled at home is a perfect idea.
Keeping the rest of the cabinet simple enough to have your local timber yard cut the required panels, ie a flat pack solution.

A DIY cutting edge 3 way floor standing design with reasonable cost is in short supply, unless I missed it?
I like the idea of separate Bass cab and a monitor type to sit on top. The monitor could be the part that gets shipped around for testing and leaves the heavy part in situ.
Bass is probably were people have the most individual requirements, I am in a room 4m X 13m and my old transmission lines just wont cut it any more. I think there are some very clever people on ASR who I hope will come up with some cutting edge approach to bass.

I look forward to seeing where this project goes.
All the best!
Ian

 

[zermak]

I would be happy to try make a cheaper version of M106. Given that this will be my first DIY speaker, I will not be able to contribute significantly except in the way of questions. Was hoping to make an active version but not sure how to select value amp and dsp modules.

I think a nice start is some of the Troels Gravesen's design. If I am not wrong and after reading the last few reviwes of these 2-way speakers I think the 61-NAC project is the closest one. I made a loudspeakers myself with the same drivers and you could get better performance using the free wave guides made for the 26ADC tweeters

 

[617]

Not much of a progress so far. Did You give up? In case, would You mind to publish the reasoning behind this?

No, just working on my measurement platform. It's coming along quite rapidly.

 

[Vij]

I think a nice start is some of the Troels Gravesen's design. If I am not wrong and after reading the last few reviwes of these 2-way speakers I think the 61-NAC project is the closest one. I made a loudspeakers myself with the same drivers and you could get better performance using the free wave guides made for the 26ADC tweeters

Thanks for the suggestion. I was looking at making an active version of the Helios or Helios CM. I have a SB Acoustics Ara Be so was looking for something more full range, going down below 30Hz. Happy to work on anything active that gets traction with the community.

 

[zermak]

I see and well, I guess the goal of this thread is having a 3-way capable of going down to 30Hz (flat?) that's why I am following and well I am interested in the active part too (and hopefully we will find some good amp with DSP for cheap because the last candidate did poorly).

 

[Jayce996]

Starting following this thread as well! I would be more interested in big speakers for my living room (1m, 1.5m heigh) but for that i might try first some open baffles like the PureAudioProject ones, Anyway, looking forward with the results obtained here

 

[Pygmy]

I just found this thread and I think it's kind of related to my "low and slow" multiyear hobby project

My project is building a pair of speakers that might resemble the Philharmonic BMR's - a BMR driver for the mids, an Isoplanar Dynamic tweeter, and a (sub)woofer driver. But no analog crossover / filter though.

I want to build an external amp unit for each speaker.
Each amp unit would have 3 class D amplifiers - one for each speaker driver - and a DSP to do the crossover / filtering.

I started out ordering a Sure 3x200W T-Amp board: https://www.parts-express.com/sure-...class-d-audio-amplifier-board-t-amp--320-3352

And a Sure ADAU1701 DSP board:
https://www.parts-express.com/dayto...-ke-kernel-dsp-expansion-2-in-3-out--325-1300

I'm using a relatively expensive Connex 600W SMPS:
https://connexelectronic.com/product/smps600rs/

Putting it together, I found out the Amp board is pretty noisy even without any input. A no go for me.
Even worse, when the DSP was connected the noise level went up to "wtf is this" level - still without any inputs connected (or inputs connected with zero level).
All with shielded cabling etc.

Now I'm considering ordering 3E Audio TPA3255 amp boards, and their DSP board.
I've read great things about 3E, and the fact the audio between the DSP and the Amp boards is balanced is a plus too.

 

[frabor]

there is a very interesting turntable thread in diyaudio

https://www.diyaudio.com/forums/multi-way/297668-polar-measurements-automatic-turntable.html

I am setting my cnc to cut my first baffle out of mdf or plywood.

My idea is to cast the whole baffle (including the waveguide) into a fiberglass mold. then you can make multiple copies of the baffle.

 

[Colonel7]

No, just working on my measurement platform. It's coming along quite rapidly.

Checking in on progress. Was there another thread created for build or testing?

 

[DDF]

Howdie, I added this to the DIY speaker testing thread, but thought it might be of more interest here

I lent ASR member Rick Sykora a hand with a new Purifi-based design that he's been working on. I found it had problems in a sealed box, and I made a recommendation for a tweeter to use. Sharing the design process here.

Box Type
Here I proposed the Purifi in a sealed box, but mentioned "Caveat: I still want to calculate the distortion created by the compression of the air itself in such a small box". Turns out, there's an issue using the Purifi in a sealed box.

If air is compressed too far, it's no longer a linear spring. Even a perfect speaker driver will have distortion from the non linear restoring force of the air in a small box, if pushed too hard.

Linkwitz here estimated the % of second harmonic distortion as =0.014*SD (in cm^2)*driver displacement(in mm)/box volume (in L).

Here's the predicted 2nd harmonic distortion with the Purifi in a sealed box (which by necessity must be small), caused by just the air itself. THD will be higher. I highlighted some measurement points from ASR and compared to the ASR vented proto test results for total HD.

The sealed distortion will be quite a bit higher than a vented because the parameters of the driver demand such a small box. You could argue about how audible this is, and in the table I show that the distortion won't be too bad when playing >300 Hz alone. OTOH, I've never tested the following theory, but I expect the mids might still distort when played simultaneously with loud bass because the air itself is distorting (Amir doesn't measure this).

The Purifi is all about playing loud with low THD, but it struggles to pull that off in a sealed box because of its unusual TS params.

Tweeter Choice
Rick had initially suggested the SB26STWGC-4. I`ve never used the SB26STWGC-4. On vs off axis looks great and it fits. But that top end is rough and would need at least a few extra components to EQ (mandatory IMO), and space will be tight

My understanding is that its a waveguide put on the SB26STC (which gets some love). I compared the STC distortion tests here to the drivers below, and the ones below have much better all important higher harmonic distortion performance. The small waveguide doesn't have enough gain (5 dB) to make up the difference. It would really be nice to have distortion measurements of it.

Other good low distortion choices with nice combination of power handling and dispersion that fit, but no waveguide

• Revel uses a variant of the SB26ADC-000-4, some great distortion numbers here and here 10dB better distortion numbers 1-2k than the DXT. Great price. Troels makes it work off axis here so the lack of waveguide might not be a big deal
• An oldie but still goodie SB26STAC, MarkK tests and here
• DA25TX00-08 is promising based on raves in this and this but its faceplate is probably too large for this build

Another choice could be SB26ADC and Augerpro`s free waveguide design here. I checked the CAD file and the 4in would definitely fit, maybe even the 5ìn (more background discussion here and here). The STAC might work in his waveguide as well

The Seas DXT is still a good turn key drop in with a nice balance of tradeoffs (waveguide, but more distortion than SB26). I was surprised to read this diva complaint from a manufacturer, as the driver looks well behaved on IEC baffle.

A ring radiator would really need a waveguide to give it enough power handling to keep up with the Purifi. I took a quick look and found a couple promising turn key combinations

• DX25TG09-04 and Monocor WG-300 waveguide, tests results here show very nice directivity and great distortion results. But the waveguide is big and might not fit

• XT25TG-30 and Monocor WG-300 waveguide, tests results here also show very nice directivivity but the distortion is much higher, the DX25 combo wins

Visaton also makes a waveguide here, though it`s also big (DIY with XT25 here wasn`t too successful). Mouser and digikey sell it. 617 found it worked best with Dayton RST28F here, haven`t found any drop ins with ring radiators. Alternatively, one of augerpros waveguides here might work for a ring, but it might not. His elliptical waveguides provide more options with small baffles. I looked at the wavecor tweeters here but their distortion results aren`t very impressive

This thread is another option to read through for candidates

SB26ADC-000-4 with or without waveguide looks like a front runner to me. Best way to predict if a waveguide is needed is to take a diffraction modeling program and model the effect of the baffle from 1 to 8 kHz, then combine with the driver IEC measurements from SB, and see if it works without a waveguide. I explain one way to do it here. Its an old write up and there are better free tools around now, but the concepts are the same.

 

[amirm]

Thanks for helping @DDF. It would be really good to use the collective knowledge of some of the experts on the forum to design something unique and great.

 

[Lbstyling]

Howdie, I added this to the DIY speaker testing thread, but thought it might be of more interest here

I lent ASR member Rick Sykora a hand with a new Purifi-based design that he's been working on. I found it had problems in a sealed box, and I made a recommendation for a tweeter to use. Sharing the design process here.

Box Type
Here I proposed the Purifi in a sealed box, but mentioned "Caveat: I still want to calculate the distortion created by the compression of the air itself in such a small box". Turns out, there's an issue using the Purifi in a sealed box.

If air is compressed too far, it's no longer a linear spring. Even a perfect speaker driver will have distortion from the non linear restoring force of the air in a small box, if pushed too hard.

Linkwitz here estimated the % of second harmonic distortion as =0.014*SD (in cm^2)*driver displacement(in mm)/box volume (in L).

Here's the predicted 2nd harmonic distortion with the Purifi in a sealed box (which by necessity must be small), caused by just the air itself. THD will be higher. I highlighted some measurement points from ASR and compared to the ASR vented proto test results for total HD.

The sealed distortion will be quite a bit higher than a vented because the parameters of the driver demand such a small box. You could argue about how audible this is, and in the table I show that the distortion won't be too bad when playing >300 Hz alone. OTOH, I've never tested the following theory, but I expect the mids might still distort when played simultaneously with loud bass because the air itself is distorting (Amir doesn't measure this).

The Purifi is all about playing loud with low THD, but it struggles to pull that off in a sealed box because of its unusual TS params.

Hello,

several of these links are not working/here.

My understanding is that the Purifi driver (if you are referring to the beast of a 6 inch one they do) works best with a passive radiator.

You could also investigate a Variovent, though I would go with a port if possible. The port issue was the size of it is very large if I remember right? Slot port the width of the cabinet and a false bottom, or even up the vertical side of the cabinet

Otherwise, some all together good clear thinking here I feel!

SB26? all good here!

 

[Rick Sykora]

Hello,

several of these links are not working/here.

My understanding is that the Purifi driver (if you are referring to the beast of a 6 inch one they do) works best with a passive radiator.

You could also investigate a Variovent, though I would go with a port if possible. The port issue was the size of it is very large if I remember right? Slot port the width of the cabinet and a false bottom, or even up the vertical side of the cabinet

Otherwise, some all together good clear thinking here I feel!

SB26? all good here!

Agree on the PR aspect and am evaluating the SPK5 that Amir tested to see if the fancy vent Purifi uses there is worth the effort to fabricate.

 

[617]

Howdie, I added this to the DIY speaker testing thread, but thought it might be of more interest here

I lent ASR member Rick Sykora a hand with a new Purifi-based design that he's been working on. I found it had problems in a sealed box, and I made a recommendation for a tweeter to use. Sharing the design process here.

Box Type
Here I proposed the Purifi in a sealed box, but mentioned "Caveat: I still want to calculate the distortion created by the compression of the air itself in such a small box". Turns out, there's an issue using the Purifi in a sealed box.

If air is compressed too far, it's no longer a linear spring. Even a perfect speaker driver will have distortion from the non linear restoring force of the air in a small box, if pushed too hard.

Linkwitz here estimated the % of second harmonic distortion as =0.014*SD (in cm^2)*driver displacement(in mm)/box volume (in L).

Here's the predicted 2nd harmonic distortion with the Purifi in a sealed box (which by necessity must be small), caused by just the air itself. THD will be higher. I highlighted some measurement points from ASR and compared to the ASR vented proto test results for total HD.

The sealed distortion will be quite a bit higher than a vented because the parameters of the driver demand such a small box. You could argue about how audible this is, and in the table I show that the distortion won't be too bad when playing >300 Hz alone. OTOH, I've never tested the following theory, but I expect the mids might still distort when played simultaneously with loud bass because the air itself is distorting (Amir doesn't measure this).

The Purifi is all about playing loud with low THD, but it struggles to pull that off in a sealed box because of its unusual TS params.

Tweeter Choice
Rick had initially suggested the SB26STWGC-4. I`ve never used the SB26STWGC-4. On vs off axis looks great and it fits. But that top end is rough and would need at least a few extra components to EQ (mandatory IMO), and space will be tight

My understanding is that its a waveguide put on the SB26STC (which gets some love). I compared the STC distortion tests here to the drivers below, and the ones below have much better all important higher harmonic distortion performance. The small waveguide doesn't have enough gain (5 dB) to make up the difference. It would really be nice to have distortion measurements of it.

Other good low distortion choices with nice combination of power handling and dispersion that fit, but no waveguide

• Revel uses a variant of the SB26ADC-000-4, some great distortion numbers here and here 10dB better distortion numbers 1-2k than the DXT. Great price. Troels makes it work off axis here so the lack of waveguide might not be a big deal
• An oldie but still goodie SB26STAC, MarkK tests and here
• DA25TX00-08 is promising based on raves in this and this but its faceplate is probably too large for this build

Another choice could be SB26ADC and Augerpro`s free waveguide design here. I checked the CAD file and the 4in would definitely fit, maybe even the 5ìn (more background discussion here and here). The STAC might work in his waveguide as well

The Seas DXT is still a good turn key drop in with a nice balance of tradeoffs (waveguide, but more distortion than SB26). I was surprised to read this diva complaint from a manufacturer, as the driver looks well behaved on IEC baffle.

A ring radiator would really need a waveguide to give it enough power handling to keep up with the Purifi. I took a quick look and found a couple promising turn key combinations

• DX25TG09-04 and Monocor WG-300 waveguide, tests results here show very nice directivity and great distortion results. But the waveguide is big and might not fit

• XT25TG-30 and Monocor WG-300 waveguide, tests results here also show very nice directivivity but the distortion is much higher, the DX25 combo wins

Visaton also makes a waveguide here, though it`s also big (DIY with XT25 here wasn`t too successful). Mouser and digikey sell it. 617 found it worked best with Dayton RST28F here, haven`t found any drop ins with ring radiators. Alternatively, one of augerpros waveguides here might work for a ring, but it might not. His elliptical waveguides provide more options with small baffles. I looked at the wavecor tweeters here but their distortion results aren`t very impressive

This thread is another option to read through for candidates

SB26ADC-000-4 with or without waveguide looks like a front runner to me. Best way to predict if a waveguide is needed is to take a diffraction modeling program and model the effect of the baffle from 1 to 8 kHz, then combine with the driver IEC measurements from SB, and see if it works without a waveguide. I explain one way to do it here. Its an old write up and there are better free tools around now, but the concepts are the same.

DDF, any consideration of a 3 way speaker? If you're set on a 2 way, I think you'll want a waveguide. The augerpro/sb26 is performant and well documented, but the new Satori BE/aluminum waveguide model should be excellent if expensive. The DXT I've never used but if you need an off the shelf tweeter which mates with normal midwoofers it's a good bet. The more robust 28/29/30mm tweeters are not really useful in my opinion - not as good as a waveguide in a two way, more expensive and poorer dispersion in a 3 way.

I'm not as familiar with the purefi little monsters, but they strike me as being happy in a relatively large box with a big port or PRs, in which case you have the room to make a 3 way. SB Acoustics has a new mid dome which is probably excellent if you want to make a SOTA old fashioned 3 way.

 

[Lbstyling]

Or Cardioid ?

It would be special, and worthy of the forum methinks.

See post 2.

https://www.diyaudio.com/forums/mul...tant-directivity-low-200hz-using-drivers.html

The enclosure issue could be a convenient problem!

In my own tests I found the same as Face, its actually rather easy to do, but requires a driver that can move some serious air to be worth it.

You would also want another driver below 200hz or so though, otherwise its like trying to fill a bucket with a big hole in the bottom.

 

[DDF]

DDF, any consideration of a 3 way speaker? If you're set on a 2 way, I think you'll want a waveguide. The augerpro/sb26 is performant and well documented, but the new Satori BE/aluminum waveguide model should be excellent if expensive. The DXT I've never used but if you need an off the shelf tweeter which mates with normal midwoofers it's a good bet. The more robust 28/29/30mm tweeters are not really useful in my opinion - not as good as a waveguide in a two way, more expensive and poorer dispersion in a 3 way.

I'm not as familiar with the purefi little monsters, but they strike me as being happy in a relatively large box with a big port or PRs, in which case you have the room to make a 3 way. SB Acoustics has a new mid dome which is probably excellent if you want to make a SOTA old fashioned 3 way.

617, I was just helping Rick, its his gig. I think he's leaning 2 way.

Beryllium price is too high. In general I'm for waveguides if done right. There is a place for the robust larger domes though. Some Scans have a peak above 8 khz and they work great on a slanted baffle as a result. The slanted baffle can allow lower crossover orders and better off axis near the bloom if paired correctly with woofers.

The purifi is a head scratcher. They have huge linear throw but trade off sensitivity for low reach. So it has amazing low distortion tech but the TS params are a problem, not so well thought out. It doesn't work sealed as it requires a box so small the air distorts. It doesn't work ideally ported since it needs a ridiculously large and long port to take full advantage of its design strengths. Which leaves passive radiator, and possibly MLTL. Passive radiators add cost to an already costly driver, and whatever suspension non linearities the PR has itself. Be interesting to sim an MLTL for it.

 

[617]

617, I was just helping Rick, its his gig. I think he's leaning 2 way.

Beryllium price is too high. In general I'm for waveguides if done right. There is a place for the robust larger domes though. Some Scans have a peak above 8 khz and they work great on a slanted baffle as a result. The slanted baffle can allow lower crossover orders and better off axis near the bloom if paired correctly with woofers.

The purifi is a head scratcher. They have huge linear throw but trade off sensitivity for low reach. So it has amazing low distortion tech but the TS params are a problem, not so well thought out. It doesn't work sealed as it requires a box so small the air distorts. It doesn't work ideally ported since it needs a ridiculously large and long port to take full advantage of its design strengths. Which leaves passive radiator, and possibly MLTL. Passive radiators add cost to an already costly driver, and whatever suspension non linearities the PR has itself. Be interesting to sim an MLTL for it.

MLTL takes away all of the portability advantages but could be an interesting choice. I have the Martin King worksheets to simulate but I wouldn't count on the accuracy with such an esoteric driver. Have we seen measurements indicating the linearity of the PR?