What is really puzzling me is full phase shift at 270Hz which is purely woofer related. Always the same thing I got; any XO or woofer alone. Always sharp phase reversal within very narrow 10 Hz range (approx from 256 to 275Hz). It results in sharp dip (like 10db) as in picture, or in uncontrolled peak with different measurements, but phase shift is always there and rapid.
If anyone is understanding this, and kind to explain, I appreciate 🙂
If anyone is understanding this, and kind to explain, I appreciate 🙂
Resonance in a box?
https://vikash.info/audio/standing_wave_calc
There are probably better calculators out there.
https://vikash.info/audio/standing_wave_calc
There are probably better calculators out there.
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Just one more positive comment for anyone that is using very low Qts woofers that actually have high Fs (like this one) and is willing to make tube enclosure
- Tube do not resonate very much 😎,
- I made under system Fs BR tube, massive as it is (d110mm and length about 85cm is and tuned at some 24 Hz in just 49 liter tube enclosure (using tube word a lot, both enclosure and BR are tubes for household sewage) . Driver Fs is 29Hz! Result with shelving bass response is down to some 23 Hz , and 20Hz - 3-4 db. Whole deep bass range 20 - 80 Hz needs to be lifted slightly to match all, but that is easy and probably not needed at all due to room response that will lift it anyway (and make total mess out of picture in process).
Hi, didn't make any without Xo at all. These are single drivers with 1st order at 410 Hz, through DCX2496 DSP plus sum response of both:
Thanks, this chart is helpful to me. It clarifies the "magic". Of course my starting point was actually "LX" minimally pass-filtered or not at all (in special cases shown in the gallery). I can imagine many widerange ~10" drivers with a single aircore, up-firing, yielding a curve not too different, just shifted. (Actually I've done a few vintage "fullrange" and modern drivers.) And a complementary front-facing fullrange, small-sealed or OB (capacitor if needed).
My diy speakers generally have to be compact and portable -- in fact I assemble them including simple XO, do a tone-sweep-by-ear, tweak a little and listen for a few hours -- before having to disassemble them and put everything away.... Truly insane but I have no choice as I sleep at the office most nights.
My diy speakers generally have to be compact and portable -- in fact I assemble them including simple XO, do a tone-sweep-by-ear, tweak a little and listen for a few hours -- before having to disassemble them and put everything away.... Truly insane but I have no choice as I sleep at the office most nights.
Happy that picture was good for you.
In recent years I was partner for Chinese company in Hangzhou (that ended in tears, but another story) . Many of colleagues also stayed in offices overnight whole week as they wanted to work hard and not waste time on traveling home.... But than 10" vintage drivers are not particularly practical 🙂. These modern 3-4" small wide ranges can be very portable and make fantastic low level sound on there own. If I would need one, I would not think twice to use B80, or F10, or some better Alcone , or Fatail for pair of micro BR speakers that I can carry around, without XO.
For my betlejuices, I still need to figure that phase reversal at 270 Hz, and flatten high frequency climb wit with some gentle shelving filter, or even thinking installing one more B80 but firing upwards from the eye?..?..? Like that I would increase mid bands and get more power while keeping highs at level as these drivers are beaming after some 4khz , so additional driver firing vertically would add little of HF to the listening place , but lot of mid's and space... Need to think, try, measure, listen...
Dears, just to ask again; what do you think is cause of rapid phase reversal at 270 Hz and how to tackle this? Like in post # 61 above.
This is strictly woofer related, no XO influence.
Another thing worth ironing (but much less of concern) is some peak followed by dip at about 2,5 kHz with the Eye. Other people measured that Visaton B80 driver and the same thing is present there (and speaker being in free air or different enclosure), completely independent from what I measured. Results are very similar (at least seems Visaton has good production spec consistency). Is it worth tackling this at all?
And the last, climbing response of widerange driver, below I plotted on axis and approx 30 deg off axis sweeps. I believe it is not good idea to do anything with that as I will never be exactly on axis to listen. Only idea that I like is might be to introduce one more B80 but firing upwards. Makes any sense?
Here are plots , on axis and 30° off (blue), they show all 3 issues:
Thanks heaps
This is strictly woofer related, no XO influence.
Another thing worth ironing (but much less of concern) is some peak followed by dip at about 2,5 kHz with the Eye. Other people measured that Visaton B80 driver and the same thing is present there (and speaker being in free air or different enclosure), completely independent from what I measured. Results are very similar (at least seems Visaton has good production spec consistency). Is it worth tackling this at all?
And the last, climbing response of widerange driver, below I plotted on axis and approx 30 deg off axis sweeps. I believe it is not good idea to do anything with that as I will never be exactly on axis to listen. Only idea that I like is might be to introduce one more B80 but firing upwards. Makes any sense?
Here are plots , on axis and 30° off (blue), they show all 3 issues:
Thanks heaps
Hello, sorry nothing happened with this in the meantime, listening this in our "cinema" room with DCX as x-o and everything is fine. Still need the time to finish details and close the project.
Nevertheless yesterday I visited machinist to make me new pulley for turntable, and asked how much would it cost to make mounting "doughnut " for small 3-4" drivers, sketch in my post #2, from aluminum.
Just taking approx size (I showed him B80 as reference): machining 10 pcs like this would be about 30Euro a piece, add post and packaging, might be reduction in price, anyway in level of 40-50 Euro delivered.
Knowing cost of these wide range drivers (B80, F10 and 9, Markaudio, jordans and so on), this doughnut will be obviously anything between 150% and 30% of driver cost, so not irrelevant.
However such precisely machined doughnut would allow for easy flush mounting small driver in the enclosure without worrying about screws being pulled out or tolerances left for gasket. With it one only needs to open hole in the enclosure in size of outer diameter of doughnut and epoxy glue it to enclosure.
His offer is worth for different driver's pairs, as long as overall dimension is similar. In other words he can make 10 pcs, example 2 for B0, 4 for F10, 6 for any other 3-4" driver at 30Euro per piece.
Does it sound interesting? Anyone has better offer? If yes I can organize group buy.
If better offer exists, I would need 7 doughnuts for all B80 drivers I have.
Nevertheless yesterday I visited machinist to make me new pulley for turntable, and asked how much would it cost to make mounting "doughnut " for small 3-4" drivers, sketch in my post #2, from aluminum.
Just taking approx size (I showed him B80 as reference): machining 10 pcs like this would be about 30Euro a piece, add post and packaging, might be reduction in price, anyway in level of 40-50 Euro delivered.
Knowing cost of these wide range drivers (B80, F10 and 9, Markaudio, jordans and so on), this doughnut will be obviously anything between 150% and 30% of driver cost, so not irrelevant.
However such precisely machined doughnut would allow for easy flush mounting small driver in the enclosure without worrying about screws being pulled out or tolerances left for gasket. With it one only needs to open hole in the enclosure in size of outer diameter of doughnut and epoxy glue it to enclosure.
His offer is worth for different driver's pairs, as long as overall dimension is similar. In other words he can make 10 pcs, example 2 for B0, 4 for F10, 6 for any other 3-4" driver at 30Euro per piece.
Does it sound interesting? Anyone has better offer? If yes I can organize group buy.
If better offer exists, I would need 7 doughnuts for all B80 drivers I have.