JamesTan
1. I know what you mean, I use that small cap in parallel to woofer inductor often.
Few other tips:
5. what is the value of woofer inductor? And what is nominal midwoofer impedance? 4 or 8ohm?
6. Did you try less or more damping material in the enclosure? I assume this is smaller 2way, ~18l BR, right? The amount of the damping material in the enclosure has quite an impact on firmness of bass and lower midrange and the clarity of midrange. More damping material often helps.
1. I know what you mean, I use that small cap in parallel to woofer inductor often.
Few other tips:
5. what is the value of woofer inductor? And what is nominal midwoofer impedance? 4 or 8ohm?
6. Did you try less or more damping material in the enclosure? I assume this is smaller 2way, ~18l BR, right? The amount of the damping material in the enclosure has quite an impact on firmness of bass and lower midrange and the clarity of midrange. More damping material often helps.
@Pida Actually I feel rather bad discussing about my speaker when this thread is started by @hifijim to discuss about his Purifi + Waveguide Project and I hope he doesn't mind. Btw thanks for your tips,
5. The inductor is 2mH and it is a 8ohm woofer.
6. I believe I have put more than enough damping material inside the enclosure and the bass and mid bass sounds pretty good for a 6 inch driver. The vocal is very clean and clear. It is actually a 25l sealed box, thought of trying a low Qtc setup and surprisingly it sounded pretty awesome.
5. The inductor is 2mH and it is a 8ohm woofer.
6. I believe I have put more than enough damping material inside the enclosure and the bass and mid bass sounds pretty good for a 6 inch driver. The vocal is very clean and clear. It is actually a 25l sealed box, thought of trying a low Qtc setup and surprisingly it sounded pretty awesome.
Looking at your off axis measurements - of course! It has wide radiation at exactly these frequencies.
That's EXACTLY the use for a Waveguide.
I believe with a waveguide the off axis measurements will be better but if I am not wrong there isn't any ready made waveguide specially for the TX tweeter selling in the market nor do I have my hands on a 3D printer. If the speakers are positioned toe-in facing the listening spot, I believe we can minimize the problem
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Taking good quality measurements is the start of being able to correlate what you hear what with you've designed. IME, if I HAD to take a single curve that best represent the power response or predicted in-room response, I would take 30 degrees. And so looking at your measurements, I feel you have a lot of bunching up at 1.6-1.8KHz- and there's simply much energy there. Too much at around 1.6KHz can make the sound take on a "tinny" character, which is the opposite side of the coin of "warmth"
I wonder if you would consider taking good polars from 0-90 degrees?
And if not yet able to, at least consider adjusting the crossover for 1-2dB less energy around that 1.6-1.8Khz region.
A quick and dirty test would be to dial in a PEQ with a Q of 3-4 around 1.7Khz and adjust down -0.5dB. -1, -1.5, -2dB steps...
Yes, maybe start a new thread where we could discuss more...
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I started a new thread for further discussion on the off axis issue, feeling bad for further "intruding" Jim's thread. Thanks for all the advice given . Discussion moved to https://www.diyaudio.com/community/threads/question-about-off-axis-measurements.401623/#post-7410611
. Discussion moved to https://www.diyaudio.com/community/threads/question-about-off-axis-measurements.401623/#post-7410611
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Wherever there is diffraction there is compromise between the 0 degree axis and all other axes, as fixing one will negatively impact the others. Taking good polar measurements and using a simulator like Vituix will allow you to "see" the effect that any EQ has on all the responses at once. The only time the listening axis dominates to make it the most important is when listening very close up so the room is supressed in perception, when listening at 2m or more the balance between listening axis and off axis becomes more important. Then any EQ that makes everything but the listening axis better is a good compromise.
Often making the listening axis 10 to 15 degrees away from 0 allows a good compromise to be reached.
Often making the listening axis 10 to 15 degrees away from 0 allows a good compromise to be reached.
Hello All,
Looks like the weather is changing here on the NorCal Coast.
I just got back a freshly calibrated GRAS 46BF-1 1/4 inch microphone, ready to make some measurements.
Woofer ScanSpeak XXLS with passive radiator
Mid-woofer 6 1/2 inch Purifi
Tweeter TW29BN-B and or SB26 aluminum. Those and a couple of others are on the shelf.
Hifi Jim,
Have you made the final adjustments or have you moved on to the next investment in fun?
How did it turn out for your effort?
Thanks DT
Looks like the weather is changing here on the NorCal Coast.
I just got back a freshly calibrated GRAS 46BF-1 1/4 inch microphone, ready to make some measurements.
Woofer ScanSpeak XXLS with passive radiator
Mid-woofer 6 1/2 inch Purifi
Tweeter TW29BN-B and or SB26 aluminum. Those and a couple of others are on the shelf.
Hifi Jim,
Have you made the final adjustments or have you moved on to the next investment in fun?
How did it turn out for your effort?
Thanks DT
I listen to these every day, both for music and for movies.
I have made a few adjustments which are fairly minor. Here is the current performance in terms of VituixCad 6-pack
I have continued to evaluate various changes I can make with the DSP. For instance, I tried several flavors of 2nd order filters between mid/tweeter. When I could tell the difference, I preferred the baseline, although it was often difficult to hear a difference.
The above filter is my current "best effort"... but tweeking will never truly be finished.
j.
Isn't our brain a wonderful thing? hahaha
Anyone who is involved in recording and mixing knows what I am talking about
Not much to add to those graphs, except the part around 150-600 Hz to make it truly constant directivity.
aka more like cardioid like behavior.
Ever so slight mismatch around 900-3000Hz, although I have my doubt how audible that is.
(the real "problem" is around 4kHz)
Send those speakers to Erin and show what some $$$$$$$ companies totally fail at!
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For a while I had a filter which had a constant -1 dB/octave PIR slope from 100 - 10k. This was achieved by a wide shallow dip of about -1.5 dB centered on 2.5k, combined with some x-over adjustments. I liked the results, and I wanted to see how it would sound. This is the magic "ASR criteria"
https://www.diyaudio.com/community/threads/purifi-waveguide-project.394174/post-7382731
It took me a long time to develop a preference, but in the long term, it turns out I prefer a more flat on-axis response.
j.
https://www.diyaudio.com/community/threads/purifi-waveguide-project.394174/post-7382731
It took me a long time to develop a preference, but in the long term, it turns out I prefer a more flat on-axis response.
j.
I was trying to give a complement!
In the end it is actually about a preference.
Even objectively speaking, we can get something to a point we all think like yeah that is great.
No issues, no resonances, no other weird problem.
But in the end, one just subjectively likes something a bit more than someone else
We are talking about nuances here
In the end it is actually about a preference.
Even objectively speaking, we can get something to a point we all think like yeah that is great.
No issues, no resonances, no other weird problem.
But in the end, one just subjectively likes something a bit more than someone else
We are talking about nuances here
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You had just some pocket money laying around?
I made the purchase from a third party. The microphone needed repair. I sent it to GRAS in Denmark for repair and calibration, turns out that the microphone was still in warranty, I was fortunate. This 1/4 inch microphone will do well for MIB measurements.
HIfi Jim,
Good job. Thanks for sharing your work and insights.
Thanks DT
Hi, nice, learning preference allows optimization and better sound!
Could you give more context about your listening setup? I mean do you utilize strong early reflections to "enhance" stereo aspects, or do you prefer less room interaction in order to get more accurate sound or how would you describe? In general, is your setup positioning freely adjustable to your liking or are you constrained to keep positioning practical, are you evaluating sound from listening spot or in general? Thanks!
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Moons ago John Krutke noted that with low non-linear distortion drivers, he had a preference for flat response. For drivers with slightly higher non-linear distortion, a slight downtilt was preferred.
Let me see if I can find what he said; in case I take it out of context-
“Tonal balance is an important consideration. Some people say they like flat and some say a tilted down response curve works best. The fact is, what works best for a design will depend on the drivers used.
The kind of tonal balance I choose is determined by the driver's distortion in it's operating range. Even if a driver measures flat, harmonic distortion may make it sound brighter than it actually is, by creating high frequencies where there should be none. So to my old ears, flat with low distortion sounds perfect. Flat with higher harmonic distortion sounds bright or edgy, and if I am designing with drivers like that, I'll generally tilt the response down at the frequency where the distortion rises. It's a delicate balance to find the right sound. Generally speaking however, flat sounds best with higher quality low distortion drivers. Cheaper drivers often require the tilt if you cannot work their distortion out of their operating range.
Tilted or flat response is one issue, but response variation is another issue. Once again, +/- 1dB could work with low distortion drivers. But designs with less than perfect drivers can be varied far from flat in the interests of removing listening fatigue. For example, I've done a design with a driver that had a large distortion peak at 1400hz. I intentionally put a high Q, 6 db deep notch right there and it sounded pretty good afterwards. Without it, high female vocals and strings caused listening fatigue. Dips in response are generally far less noticable than peaks, and may be needed to solve a problem.
Don't forget the room. Generally, flat sounds good in a carpeted room, but hardwood or tiled floors can increase the aparent brightness.
In case it's not obvious yet, distortion management is the most important issue in design. Folks that fire up LspCAD and pop out a design without doing distortion testing have success rates that are essentially just based on luck. You've got to know your drivers well before you pair them up, select a crossover point and crossover topology. Without distortion tests, it's a shot in the dark, and design iterations may go on endlessly in the course of finding something that works. When you start your design process armed with full distortion data, the chances you're going to get the design right on the first try or soon thereafter. Without distortion data, you may never figure out what's wrong with a design.
Smart driver pairing will increase the chances of success. No offense to fans of the ProAc 2.5 clone, but it makes a great example of poor driver pairing. The Scan Speak 8513 has heavy harmonic distortion anywhere below 4kHz, while the 8535 woofer has energy storage issues above 2kHz, along with poor off axis response. A compromised crossover point at 3kHz can't save this system and the result is a harsh, edgy sound. Crossing a 7" woofer at 3kHz also results in a narrow vertical listening window and a rough power response.
Generally, all things being equal, I'll cross a tweeter over as low as I can before distortion and Xmax start to become issues for the level I listen at. As you cross over lower, the vertical listening window becomes taller. Once again, pairing drivers and selecting a crossover point is a delicate balance.”
Reference:
under Design sub-heading:
http://www.zaphaudio.com/mantras.html
Let me see if I can find what he said; in case I take it out of context-
“Tonal balance is an important consideration. Some people say they like flat and some say a tilted down response curve works best. The fact is, what works best for a design will depend on the drivers used.
The kind of tonal balance I choose is determined by the driver's distortion in it's operating range. Even if a driver measures flat, harmonic distortion may make it sound brighter than it actually is, by creating high frequencies where there should be none. So to my old ears, flat with low distortion sounds perfect. Flat with higher harmonic distortion sounds bright or edgy, and if I am designing with drivers like that, I'll generally tilt the response down at the frequency where the distortion rises. It's a delicate balance to find the right sound. Generally speaking however, flat sounds best with higher quality low distortion drivers. Cheaper drivers often require the tilt if you cannot work their distortion out of their operating range.
Tilted or flat response is one issue, but response variation is another issue. Once again, +/- 1dB could work with low distortion drivers. But designs with less than perfect drivers can be varied far from flat in the interests of removing listening fatigue. For example, I've done a design with a driver that had a large distortion peak at 1400hz. I intentionally put a high Q, 6 db deep notch right there and it sounded pretty good afterwards. Without it, high female vocals and strings caused listening fatigue. Dips in response are generally far less noticable than peaks, and may be needed to solve a problem.
Don't forget the room. Generally, flat sounds good in a carpeted room, but hardwood or tiled floors can increase the aparent brightness.
In case it's not obvious yet, distortion management is the most important issue in design. Folks that fire up LspCAD and pop out a design without doing distortion testing have success rates that are essentially just based on luck. You've got to know your drivers well before you pair them up, select a crossover point and crossover topology. Without distortion tests, it's a shot in the dark, and design iterations may go on endlessly in the course of finding something that works. When you start your design process armed with full distortion data, the chances you're going to get the design right on the first try or soon thereafter. Without distortion data, you may never figure out what's wrong with a design.
Smart driver pairing will increase the chances of success. No offense to fans of the ProAc 2.5 clone, but it makes a great example of poor driver pairing. The Scan Speak 8513 has heavy harmonic distortion anywhere below 4kHz, while the 8535 woofer has energy storage issues above 2kHz, along with poor off axis response. A compromised crossover point at 3kHz can't save this system and the result is a harsh, edgy sound. Crossing a 7" woofer at 3kHz also results in a narrow vertical listening window and a rough power response.
Generally, all things being equal, I'll cross a tweeter over as low as I can before distortion and Xmax start to become issues for the level I listen at. As you cross over lower, the vertical listening window becomes taller. Once again, pairing drivers and selecting a crossover point is a delicate balance.”
Reference:
under Design sub-heading:
http://www.zaphaudio.com/mantras.html
tktran303: I agree, I also prefer more flat with better, low distortion drivers. I would add, that +-0.5dB differences in critical areas (~600Hz, 3kHz, 6kHz,...) make very noticeable audible difference (more noticeable with low distortion drivers), though comparison of spinoramas before/after change might be difficult as they look basically the same, basically still flat. Some drivers combination need mild lift here and there, or mild dip, to make it sound right and balanced. And that is the trouble I see with spinorama and paying too much focus to it and judging the sound only by spinorama. I do not mean it that I see it here on DIYA, I mean it more generally. All I wanted to say is that very mild deviations from flat are not bad thing and everyone looking at spinorama graphs should keep that in mind, not overanalyze/overthink the graphs, and most important - make the experience by doing/building/measuring/listening.
I agree too, "voicing" is important and sadly room- and listener-dependant. Flat on-axis and smooth PIR don't tell everything. What every desing must have is minimal small wiggles in response and no distortion peaks. Then the end-user can easily adjust voicing by old fashioned bass/treble knobs! And the loudness/mid knob that Yamaha uses!
Bass performance comes mostly from woofer(s) Sd and Xmax, and then again by preference from BR tuning/sealed construction.
Bass performance comes mostly from woofer(s) Sd and Xmax, and then again by preference from BR tuning/sealed construction.