Looking into various options for 4.5" driver to achieve 42Hz -3dB in a 13 x 15 room typical volume 70dB.
Unfortunately the low dB listening doesn't seem to offer much help in gaining extra bass response.
Counter-intuitively, changing port length or closer to wall speaker placement makes negligible improvement. FR is still shelved down below 100Hz.
I have used DSP to depress the midrange. Can't decide if it is better to live with the loss of bass compared to the reduction in sound quality, albeit with less midrange giving the appearance of more bass, that you get with DSP.
1) Baffle step correction passive components.
2)Transmission line - Sibelius or NSMT Bossa Nova.
3) Use 2) 4.5" drivers. One runs full range with no passive components. The second just used to boost FR below 100 Hz. I would feel more confident if I had the skill of Sandy Gross who knows how to design x-overs to focus the sound of multiple drivers to sound like one but with more clarity and impact.
...3a) Run 2 but in opposition. One driver on front baffle and other on back. That would eliminate sound waves from the 2 drivers interfering with each other.
4) Give up and go with 6" like the Alpair.
5) Open baffle.
My limited experience with both transmission line and long-throw drivers both have slow bass and kind of bloated. You get more bass but not the kind of quality you get with 6-10" woofer.
Unfortunately the low dB listening doesn't seem to offer much help in gaining extra bass response.
Counter-intuitively, changing port length or closer to wall speaker placement makes negligible improvement. FR is still shelved down below 100Hz.
I have used DSP to depress the midrange. Can't decide if it is better to live with the loss of bass compared to the reduction in sound quality, albeit with less midrange giving the appearance of more bass, that you get with DSP.
1) Baffle step correction passive components.
2)Transmission line - Sibelius or NSMT Bossa Nova.
3) Use 2) 4.5" drivers. One runs full range with no passive components. The second just used to boost FR below 100 Hz. I would feel more confident if I had the skill of Sandy Gross who knows how to design x-overs to focus the sound of multiple drivers to sound like one but with more clarity and impact.
...3a) Run 2 but in opposition. One driver on front baffle and other on back. That would eliminate sound waves from the 2 drivers interfering with each other.
4) Give up and go with 6" like the Alpair.
5) Open baffle.
My limited experience with both transmission line and long-throw drivers both have slow bass and kind of bloated. You get more bass but not the kind of quality you get with 6-10" woofer.
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Hmm. It should be an improvement although it may take time to find what to work on. Not only do you need the midrange shelving to cut at the right frequency/rate/level, you should consider how the bass below the baffle step is subject to more room interference. Also the baffle step can have a bump, the bass can be desirable with a small boost below 100Hz (be careful not to bloat the voice region).
It could help to take multiple (spatially diverse) in room measurements and average them to get a handle on the sub 1kHz performance.
The first uses a 5.25” driver and should be near your low frequency target, it is a folded ML-Voigt.
The second an end-loaded pipe (3” ABS?), probably a 3” driver, line too restrictive and, for the driver, too long. They sensibly specifity F10 and F6 which are much more useful numbers for figuring how low they go, -3 dB is a meaningless thing to the ear/brain (ref Toole).
Frugel-Horn Lite, uses 3” drivers and gets to something like 60-65 F6, Frugel-Horn XL with suitable driver meets your LF needs, uses a range of 5.25-6.5” drivers.
Not many 4.5” FRs, the FF125wk, FE126 won’t go that low comfortably…
Now at low levels with lots of EQ, power, and excursion you can get that LF out of a suitable sealed box.
You intro suggests you are playing with something already?
dave
Agreed AllenB. I was referring to running the driver with no eq sounds better but less bass. DSP gives more bass but sound quality is worse. IMHO DSP sound deterioration is similar to type of sound improvement / degradation from swapping out cables. YMMV.
Hi Dave, Thanks for Frugel-Horn XL idea. The Fostex Xmax is .35 up to 1.65mm. I'm using 6-9mm. Sibelius is nice and no whizzer but $5,000 for an Alpair...,,,
Yes I'm using a .25ft3 Pars Express cabinet. Front baffle is removable so it makes it easy to try out different drivers. Add wood blocks inside to vary volume.
I was really surprised the port tuning and room placement didn't make much difference. DSP was marginally more effective. In this particular room they act something like a line array as far as SPL drop/meter or headphones.as for directness. The tweeter cancels out some of the midrange bump. There is a crazy huge resonance of the entire room at about 40Hz no matter what I do. All this is very strange compared to what theory tells me should be happening.
I've cranked up the EQ but IMHO, the best balance of sound quality / bass was setting EQ at 50% of what is needed to be flat FR. Would be interesting to try a sealed box.
I like doubling up on the drivers but no one does it so I guess there is a good reason for it. Maybe because the cone area of (2) 4" = (1) 6".
Hi Dave, Thanks for Frugel-Horn XL idea. The Fostex Xmax is .35 up to 1.65mm. I'm using 6-9mm. Sibelius is nice and no whizzer but $5,000 for an Alpair...,,,
Yes I'm using a .25ft3 Pars Express cabinet. Front baffle is removable so it makes it easy to try out different drivers. Add wood blocks inside to vary volume.
I was really surprised the port tuning and room placement didn't make much difference. DSP was marginally more effective. In this particular room they act something like a line array as far as SPL drop/meter or headphones.as for directness. The tweeter cancels out some of the midrange bump. There is a crazy huge resonance of the entire room at about 40Hz no matter what I do. All this is very strange compared to what theory tells me should be happening.
I've cranked up the EQ but IMHO, the best balance of sound quality / bass was setting EQ at 50% of what is needed to be flat FR. Would be interesting to try a sealed box.
I like doubling up on the drivers but no one does it so I guess there is a good reason for it. Maybe because the cone area of (2) 4" = (1) 6".
Retail, art level quality woodwork by talented craftsmen, low volume. The price is perfectly reasonable.
You can diy something really close (at least) for $500-600 if you diy, much more if you make it out of 1” thick french oak.
dave
2 should be in a box 2 x as large. Filter the lower one near the baffle step F(-3) using an inductor in series with one driver will give you an approx 6 dB bump hopefully nicely countering the baffle step. In a room, particualrily near a boundary, will often be excessive. With drivers wired in series and a big cap shunting one of them you get twice the cone area, so they are both working less hard in the bass.
What is the nominal impedance of your driver. And what is it? Without more information 7 litres is meaningless.
dave
What is the nominal impedance of your driver. And what is it? Without more information 7 litres is meaningless.
dave
Just a quick note that according to this online tool: http://www.baudline.com/erik/bass/xmaxer.html
40Hz@70dB@1m should be well within the reach of most 4" drivers running sealed, with 1.36mm of one-way excursion required from a single 4" driver.
Which DSP are you using? - I'd look at improving that first.
Chris
40Hz@70dB@1m should be well within the reach of most 4" drivers running sealed, with 1.36mm of one-way excursion required from a single 4" driver.
Which DSP are you using? - I'd look at improving that first.
Chris
I added blocks so the current size is .17ft3. So is easy to increase back to the .25ft3 - still a little small, I know. They are 8 ohm.
Can I skip the baffle step if I use 2 drivers? What about radiation pattern? There will be some cancellation?
Right now is
Tang Band W4-616SA
Considering
Tang Band W4-1879
and
Tang band W5-2143
Leaning to the W5 as I have not liked TB's bamboo or neo motor or long throw drivers. Also prefer smaller Xmax although 5" is worse midrange. Best IMO is ferrite with C37 paper cone.
Can I skip the baffle step if I use 2 drivers? What about radiation pattern? There will be some cancellation?
Right now is
Tang Band W4-616SA
Considering
Tang Band W4-1879
and
Tang band W5-2143
Leaning to the W5 as I have not liked TB's bamboo or neo motor or long throw drivers. Also prefer smaller Xmax although 5" is worse midrange. Best IMO is ferrite with C37 paper cone.
Hi Chris
Dayton Audio DSP-408 4x8 DSP
If you know a better one, please share.
I liked it pretty good. Spec'd much better than MINI DSP as their nano is N/A.
I have run it sealed but bass is gone. Despite what calculations show.
Dayton Audio DSP-408 4x8 DSP
If you know a better one, please share.
I liked it pretty good. Spec'd much better than MINI DSP as their nano is N/A.
I have run it sealed but bass is gone. Despite what calculations show.
ML-Voigt is a crude horn, FHXL much more sophisticated.
FHXL is room dependent so bass extention is impacted by where in the room likely more so than Sibelus. The parts bin A10x Harley uses is closest to the Alpair 10.3, likely not as smooth and controlled at the top with less bass potential, but the FHXL mostly dominates there. FHXL can get to 25 Hz F10 (at least) before room gain, i have little idea how low Sibelis goes. What is special about Sinilus is the French Oak.
dave
FHXL is room dependent so bass extention is impacted by where in the room likely more so than Sibelus. The parts bin A10x Harley uses is closest to the Alpair 10.3, likely not as smooth and controlled at the top with less bass potential, but the FHXL mostly dominates there. FHXL can get to 25 Hz F10 (at least) before room gain, i have little idea how low Sibelis goes. What is special about Sinilus is the French Oak.
dave
I don't think DSP itself is the issue.
If you boost the bass or attenuate the rest of the spectrum its the same thing.
Driver will work harder at LF with more cone excursion. Plus, ratio of LF/HF excursion is raised so driver distortions will rise exponentially. Better quality driver can help, but increased distortions is something you can't avoid at the end.
Another possible issue is vented box tuning frequency. Below Fb, excursion will rise exponentially without effect (acoustical short circuit).
So, if you aim at f3=42Hz than Fb can't be above that.
And below Fb, you must cut the response down to protect the driver from the boost
Try this way:
-Vb should be equal to closed box with Q around 0,7
-Set the Fb to around 0,5 Fs
-Add active shelf LF boost. 2nd order, Q=0,7 , centered between Fb and Fs
-Add active high-pass, 2nd order, set at Fb to protect the driver below Fb (important!)
-Add desired level of BSC
I made some sims in Boxim with Visaton B100 4in FR driver to show this.
7 liter/0,25 cu.ft. vented box tuned to 40Hz with 15x25 cm front baffle. Free space.
First graph is driver only response.
Second is response with bass boost.
Third is response with bass boost + full BSC.
Fourth is electric response from filters
Fifth is active filters list
Sixth is max SPL and driver input voltage before Xmax
You should be able to replicate this with DSP.
Note that with all the active boost max voltage at driver terminals in working range drops to 1,3V or 1/4 Watts at drivers 6 Ohm impedance.
Still, over 80dB is possible before Xmax.
Attachments
What about Pluvia 7, down to 40Hz (not clear if F0 or F3)?
https://www.markaudio.com/wp-content/uploads/2019/06/Pluvia-Seven-HD-gen-2-spec-sheet.pdf
https://www.markaudio.com/wp-content/uploads/2019/06/Pluvia-Seven-HD-gen-2-spec-sheet.pdf
Pluva 7 is different than Pluvia 7HD. An evolution of the Alpair 7.3, with the new improved basket. Well placed, I’m guessing, 35 Hz or so in FH3, maybe lower, siililar in Pensil. The horn provides gain at the lowest frequencies. Levels are limited by the 4” driver.
IMO, very good mid-thru top, bass in the right box can be surprising (search “surprised by how much bass a 4" can put out”). Some may complain about HF resonances, i never had an issue, but i also tweak my drivers.
Makes a good midTweeter in a WAW. So does Alpair 5.2/3 (CHN-50 if you are on a tight budget), and i expect the MAOP version (it should be killer in that application).
Markaudio, starting with the second generation has done a lot to make sure his metal drivers do not fall into the generalized “metal cone sound”.
dave
IMO, very good mid-thru top, bass in the right box can be surprising (search “surprised by how much bass a 4" can put out”). Some may complain about HF resonances, i never had an issue, but i also tweak my drivers.
Makes a good midTweeter in a WAW. So does Alpair 5.2/3 (CHN-50 if you are on a tight budget), and i expect the MAOP version (it should be killer in that application).
Markaudio, starting with the second generation has done a lot to make sure his metal drivers do not fall into the generalized “metal cone sound”.
dave
I somehow missed there is a Pluva 7, thank you for the correction. 
Understand four inches limits it, figured the cabinet width might be set and the larger version would not meet the design criteria.
I was slightly concerned about this, though seemed from the two videos (which of course not a true representation and listing at the transients), glad they are not. Love how clear and detailed they sound, wow. I thought maybe Chuck like to give a listen.
Understand four inches limits it, figured the cabinet width might be set and the larger version would not meet the design criteria.
I was slightly concerned about this, though seemed from the two videos (which of course not a true representation and listing at the transients), glad they are not. Love how clear and detailed they sound, wow. I thought maybe Chuck like to give a listen.
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Hi Davor. Thanks for all the graph and simulation. You show that it is possible if listening at 80Db or lower.
The increased distortion pretty much matches what I hear when I boost the bass to make it flat.
So it seems simpler to me why not add a second identical driver for -100Hz? That will reduce LF distortion and eliminate a bunch of the bass boost electronic stuff you mention.
But will I still need BSC? That looks the be a problem no matter what driver I use. Is there any way to avoid that other than mount it on a 4 foot piece of plywood?
Davor, do you have any opinion on DSP vs passive components? Which will cause less damage to sound quality?
The increased distortion pretty much matches what I hear when I boost the bass to make it flat.
So it seems simpler to me why not add a second identical driver for -100Hz? That will reduce LF distortion and eliminate a bunch of the bass boost electronic stuff you mention.
But will I still need BSC? That looks the be a problem no matter what driver I use. Is there any way to avoid that other than mount it on a 4 foot piece of plywood?
Davor, do you have any opinion on DSP vs passive components? Which will cause less damage to sound quality?
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