Here is my first draft of a design and construction document for this project. My goal is that this document would enable someone to replicate this speaker, without having to study all 680+ posts in this whole thread.
Very nicely done, Jim. Your professional engineering experience shines through in the clarity & precision of your documentation. 💯
Jim, you can add a link to the document in your profile text! https://www.diyaudio.com/community/members/hifijim.471528/#about
I have updated the documentation for this project. As I mentioned above, my goal is that this document would enable someone to replicate this speaker, without having to study all 680+ posts in this whole thread.
I may have mentioned to several people that I was bringing this speaker to the InDIYanna event. Unfortunately, I will not be attending this year.
j.
j.
This is one of the best documentation for a DIY speaker I have read. No head scratching, everything explained, excelent pictures.
Only thing that may be an option, is to do it active 3-way. Leaving out all passive x-over parts may be an advantage.
This could be done without or very little extra cost, if you replace the mini DSP by the DSPB-K DSP Kernel Board and DSPB-KE Kernel DSP Expansion 2-In 3-Out.
Which will mean a little more thinkering how to make the whole thing look neat and use the less comfortable programing in SIGMA Studio.
A nice alternative to the amp you use is the AIYIMA A07 or 07max. It is around 50$ a piece.
Only thing that may be an option, is to do it active 3-way. Leaving out all passive x-over parts may be an advantage.
This could be done without or very little extra cost, if you replace the mini DSP by the DSPB-K DSP Kernel Board and DSPB-KE Kernel DSP Expansion 2-In 3-Out.
Which will mean a little more thinkering how to make the whole thing look neat and use the less comfortable programing in SIGMA Studio.
A nice alternative to the amp you use is the AIYIMA A07 or 07max. It is around 50$ a piece.
If this suffices, it may be a workable solution.
DSP and Bluetooth onboard.
Full review here:
https://diy.midwestaudio.club/discussion/comment/48302/#Comment_48302
In general there are two types of DSP. The ones with a GUI like the MiniDSP and the ones that need SIGMA Studio to do the programing of the DSP.
As the first is usualy self explaining, you just load an app and connect with an USB cable, the Sigma Studio dependent are another breed. They are much more complicated to manage. Not everyone will like this.
This is a very huge difference!
As the first is usualy self explaining, you just load an app and connect with an USB cable, the Sigma Studio dependent are another breed. They are much more complicated to manage. Not everyone will like this.
This is a very huge difference!
I have updated the documentation... Hopefully this is the final update (but is documentation ever really complete?)
Changes:
Rearranged the order of pages for better cohesive flow.
Added an explanation of the active/passive filter philosophy.
Corrected the passive crossover schematic.
Improved some wording and grammar for better clarity
Fixed a few typos and spelling errors.
Changes:
Rearranged the order of pages for better cohesive flow.
Added an explanation of the active/passive filter philosophy.
Corrected the passive crossover schematic.
Improved some wording and grammar for better clarity
Fixed a few typos and spelling errors.
Jim, have you measured the TS parameters of your RS270? There are reports that the manufacturer's provided specs can be off by as much as two times. Crazy.
https://www.justdiyit.com/grand-comparatif-de-10-pouces-partie-1/3/
https://www.justdiyit.com/grand-comparatif-de-10-pouces-partie-1/3/
I'm looking into RS270-8 for a 3-way as well. 20-25 L sealed, TC9FD18-08 as mid and SB26CDC-C000-4 on top, 3-way active. I want to boost the bottom with Linkwitz Transform or Shelving Low-Pass.
But I don't know what to expect really from the bottom end. I have an idea to get a sub driver for the bottom and cross it as low as TC9FD18-08 will allow distortion-wise.
But I don't know what to expect really from the bottom end. I have an idea to get a sub driver for the bottom and cross it as low as TC9FD18-08 will allow distortion-wise.
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I did a simplified free-air impedance sweep, which gives me Fs, Qts, Qes, Re, and Le. I did not do the added-mass method to determine Vas. Here is what I got, after break-in, compared to the spec:
Woofer #1
Woofer #2
The two drivers are well matched to each other, but Fs is off by about 28%. For my purposes, in a DSP-EQ'd sealed box, it is not a significant issue.
j.
Woofer #1
Woofer #2
The two drivers are well matched to each other, but Fs is off by about 28%. For my purposes, in a DSP-EQ'd sealed box, it is not a significant issue.
j.
Normally I would suggest measuring at a higher output voltage, but unfortunately DATS is far to limited for this.
That's an interesting observation, and it seems to be very closely aligned with the findings of the research conducted by Rotter and Lindau (2010), "Audibility of tweeter performance beyond spectrum and phase", available here. They concluded that: "When eliminating frequency and phase response irregularities, baffle and room interaction, non-linear behavior, and distance effects, a blind-comparison listening test could not reveal audible differences between different types of tweeters. Neither the material nor the actuator principle, neither the tweeters geometry nor the specific form of wave fronts in the far field could be shown to be distinctive features of different tweeter types."
I would like to generalize the previous to mids and woofers. Directivity differencies can be heard in normal rooms however!
This test was performed in a large anechoic chamber and binaural becordings were listened/evaluated 40 times in ABX manner with Stax headphones by ten subjects. Well executed procedure IMO.
I've noticed that many diyers "rate" drivers by listening to them without any xo or eq. Even Yevgeniy of HifiCompass, when I asked him!
This test was performed in a large anechoic chamber and binaural becordings were listened/evaluated 40 times in ABX manner with Stax headphones by ten subjects. Well executed procedure IMO.
I've noticed that many diyers "rate" drivers by listening to them without any xo or eq. Even Yevgeniy of HifiCompass, when I asked him!
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And I have not found any value in listening to a raw driver. It may work for some people, but it does nothing for me.
If that's true, then there is not much value in his listening impressions. All speakers have driver EQ/tuning be it analog, active or digital.