Future DIY Speaker Testing Strategy?

[DeruDog]

A mixed strategy would be for members to send their own builds and for Winklewizard (and/or others as well) to make those speakers for testing that are in highest demand. There is risk of erroneous construction that does not represent the design well (this is not an issue if Winkleswizard constructs all DIY reviews).

I'm in favor of limited continuance of DIY speaker testing for two reasons. First, DIY measurements are of high value to a small number of people but the value it add to us folks is incredibly high. Second, DIY reviews are educational to all enthusiasts because it adds valuable perspective on the raw materials cost as compared to commercial offerings. For non-DIY audiophiles, this perspective gives them more information to make decisions about whether brand, support, resale value, and high quality finishes are worth the price over DIY options. This information may even encourage the marginal consumer to pay for boutique cabinet construction so they don't have to DIY.

I'd be happy to contribute my speakers if the community desires. I built a pair of the ER18DXT's that received some discussion in the wonderful compilation thread from Ilkless. Most interesting to ASR is the stepped waveguide "DXT Lens" tweeter found in many, science-based, high-end designs such as the Kii Three and Grimm Audio speakers. I mention this as an example of how the whole community could gain some knowledge if we test speakers such as this one. Another example are the SEOS waveguide speakers - I've seen some interest in these on ASR already and there are accessible pre-packaged kits from DIY Sound Group for those on the fence about DIY. Perhaps I'll build some of the latter to hold me over should I end up sending my ER18DXT to the other coast...

*Edited for clarity

Is the ER18 DXT still available as a design? It is difficult to find the build instructions for me. If not, then it is less interesting as a design for decision making about speaker purchase, though it would be interesting as academically to speaker designers. I guess it depends on Amir's intent and the desires of the community.

 

[Mashcky]

Is the ER18 DXT still available as a design? It is difficult to find the build instructions for me. If not, then it is less interesting as a design for decision making about speaker purchase, though it would be interesting as academically to speaker designers.

It’s still available in that the archived website is available with a quick search and the drivers are still widely available. There are not any kits available that I’m aware of. The reason I settled on the design In spite of its age is that the designer went through greater trouble than most to measure it and aimed for a smooth power response, goals that are important to ASR.

I guess it depends on Amir's intent and the desires of the community.

Agreed.

 

[somebodyelse]

Is the ER18 DXT still available as a design? It is difficult to find the build instructions for me. If not, then it is less interesting as a design for decision making about speaker purchase, though it would be interesting as academically to speaker designers. I guess it depends on Amir's intent and the desires of the community.

https://er18dxt-backer.blogspot.com/2013/12/overview_8.html
https://web.archive.org/web/2010010...tics.org/projects_gallery/ER18DXT/ER18DXT.htm

 

[Mudjock]

https://er18dxt-backer.blogspot.com/2013/12/overview_8.html
https://web.archive.org/web/2010010...tics.org/projects_gallery/ER18DXT/ER18DXT.htm

FWIW, I would consider the ER18 DXT a design from a "credible" designer. It does appear that drivers are still available at Madisound. I used the Seas DXT tweeter in a somewhat similar project and was quite happy with it.

 

[Jukka]

Strong yes for DIY

Just take a look at this diy-audio-pornography: Faital 3WC-15! Imagine that on a spin-bench

Troels says that the smaller version, Faital 3WC, is his fastest selling design, so I think the builder base for his work is quite large. At least here in Europe. Either one of these two would be great to test. Both objective and subjective impressions and comparing to others in the price range. That's a factor when price climbs.

 

[Lbstyling]

Strong yes for DIY

Just take a look at this diy-audio-pornography: Faital 3WC-15! Imagine that on a spin-bench

Troels says that the smaller version, Faital 3WC, is his fastest selling design, so I think the builder base for his work is quite large. At least here in Europe. Either one of these two would be great to test. Both objective and subjective impressions and comparing to others in the price range. That's a factor when price climbs.

Significantly louder off axis at 30degrees between 1200 and 1800khz than on axis. No ta. (3WC)

Here's an alternative to consider.....

Quite a claim for a $350 kit. Think we need to get our hands on one of these.

 

[Jukka]

Significantly louder off axis at 30degrees between 1200 and 1800khz than on axis. No ta. (3WC)

Here's an alternative to consider.....
View attachment 80068

Quite a claim for a $350 kit. Think we need to get our hands on one of these.

I don't follow. It's true that a narrow range is louder off axis than on axis, but otherwise Faital 3WC has quite uniform horizontal dispersion (all contours are within a few dB until 15 kHz), which is more important that the actual degree of dispersion. This is a large 3-way on a 375 x 680 mm baffle after all.

 

[Lbstyling]

I don't follow. It's true that a narrow range is louder off axis than on axis, but otherwise Faital 3WC has quite uniform horizontal dispersion (all contours are within a few dB until 15 kHz), which is more important that the actual degree of dispersion. This is a large 3-way on a 375 x 680 mm baffle after all.

All else being equal, would you recommend picking it over the linked alternative? Subjective visuals aside, I cant see how they even compare, yet the Denovo is cheaper.

Troels' job is to sell crossover components. He does it well. He also tunes by ear, and is not young.

Of course, we would need distortion data, but the celestion comp driver used in my linked example is one of the best performing units available without going to BE.

 

[Jukka]

All else being equal, would you recommend picking it over the linked alternative? Subjective visuals aside, I cant see how they even compare, yet the Denovo is cheaper.

Troels' job is to sell crossover components. He does it well. He also tunes by ear, and is not young.

Of course, we would need distortion data, but the celestion comp driver used in my linked example is one of the best performing units available without going to BE.

Your right, they can't compare with just one graph.

Jokes aside, I'm fan of big PA. I tried to search that, but can't find. Are they still available new? Or can you share the specific model number?

 

[Lbstyling]

Your right, they can't compare with just one graph.

Jokes aside, I'm fan of big PA. I tried to search that, but can't find. Are they still available new? Or can you share the specific model number?

It's the Denovo 15 from DIYsoundgroup.

It's been taken off the website for now due to covid supply issues/they are moving to a bigger warehouse.

 

[BostonJack]

I'm gathering materials (and strength) to DIY a pair of DTX-MON speakers. I'm apt to be a bit of a slow builder but, ultimately, would love to see one spin tested.

for yucks, here is my choice of inserts for speaker mounting holes (they come from the AT ski industry, where ski binding swapping and strong insert pull out strength are critical):

https://www.bindingfreedom.com/threaded-inserts-for-skis-25-pack/

I have the taps and tools for these.

have purchased the DTX-MON plans and I think I understand most of them.

Jack

 

[DDF]

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 as I thought it might be of interest.

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.

 

[BrokenEnglishGuy]

Diy speakers World is really nice!!