This is the new thread for the 2x 21" down-firing-port subwoofer build(2x B&C 21SW152-4), it was previously discussed HERE in regards port design suggestion.
This 21" subs will replace the current single Ultimax UM18-22 in a 5-FT^3 sealed enclosure, wanted some lows, strong midbass and low distortion on my 2CH music setup.
Final project specs:
Material: 6x 5/8" MDF-Light 4'x8' sheets.
Measures: 42" H x 24" W x 27" D, (46" H with feet), nominal.
Walls: ~1.25"(dual 5/8") thick walls, ~1.9"(triple 5/8") baffle with braces.
Finish: Black-mate laminate.
Volume: ~9.5 FT^3 Net. after port/driver/bracing.
Weight: ~222 lbs (~180 lbs without driver)
Initial subwoofer testing/setup:
DSP: DBX DriveRack PA2
High-pass xover: 16Hz BW4
Low-pass xover: 60Hz LR4
PEQ's: Off
Delay: Off
Subharmonic Synth: Off
My "subjective" listening impressions:
After getting them in place and connected, I've played some EDM and Pop music and I was a bit skeptical at first, then I remembered that I had to invert the subs phase, after inverting the phase resulted in an instant jaw-drop followed by an ear-to-ear smile, one box just blown away the sealed UM18-22 and I've disable the PEQ's previously boosting the 20~28Hz range on the sealed sub.
Notes worth mentioning:
The B&C 21SW152-4 drivers were installed without any breaking-time, so the subs will significantly dig lower overtime as expected.
The room measurements are 10'-9"W x 9'-2"D x 8'-4"H, just small.
The enclosures were tuned to ~19Hz regarding WinISD, however since the 8" port clearance from top wall is 7.75", port clearance from floor is 4" plus 2 large pillows, the final tuning dropped to around~17 or 18Hz, while I don't had at hand DATSv3 nor a diy impedance jig, I've tested with an adhesive tape and cranked up the amplifier and used a tone generator, so far when the tone generator was set to 17Hz, the woofer drop excursion dramatically and everything in the room was insanely shaking and I feel the high pressure, I didn't hear any port noise/compression when testing so far.
Complete step by step build log HERE
Some build images:
The triple front baffles.
Deluxe 6 prong T-Nuts epoxied.
The Ankh shaped braces and port support.
Gluing started next to a 16oz glue bottle for size reference, I've used my favorite glue TB3.
The braces in place.
Interior view of the port supporters embedded on the braces.
Spreading a generous amount of glue per brace and top/bottom walls.
Internal preview of one box almost ready, back wall non yet glued.
Port dry-run test before sealing it with RTV and gluing the back wall.
Port top/brace clearance.
Port being sealed with 100% RTV.
Applying few turns of Scotch blue tape for port tighten.
Port being evenly pushed gently with a small piece of wood scrap and a rubber hammer.
Port back view.
Complete step by step build log HERE
For reference the mains build log HERE
Regards
This 21" subs will replace the current single Ultimax UM18-22 in a 5-FT^3 sealed enclosure, wanted some lows, strong midbass and low distortion on my 2CH music setup.
Final project specs:
Material: 6x 5/8" MDF-Light 4'x8' sheets.
Measures: 42" H x 24" W x 27" D, (46" H with feet), nominal.
Walls: ~1.25"(dual 5/8") thick walls, ~1.9"(triple 5/8") baffle with braces.
Finish: Black-mate laminate.
Volume: ~9.5 FT^3 Net. after port/driver/bracing.
Weight: ~222 lbs (~180 lbs without driver)
Initial subwoofer testing/setup:
DSP: DBX DriveRack PA2
High-pass xover: 16Hz BW4
Low-pass xover: 60Hz LR4
PEQ's: Off
Delay: Off
Subharmonic Synth: Off
My "subjective" listening impressions:
After getting them in place and connected, I've played some EDM and Pop music and I was a bit skeptical at first, then I remembered that I had to invert the subs phase, after inverting the phase resulted in an instant jaw-drop followed by an ear-to-ear smile, one box just blown away the sealed UM18-22 and I've disable the PEQ's previously boosting the 20~28Hz range on the sealed sub.
Notes worth mentioning:
The B&C 21SW152-4 drivers were installed without any breaking-time, so the subs will significantly dig lower overtime as expected.
The room measurements are 10'-9"W x 9'-2"D x 8'-4"H, just small.
The enclosures were tuned to ~19Hz regarding WinISD, however since the 8" port clearance from top wall is 7.75", port clearance from floor is 4" plus 2 large pillows, the final tuning dropped to around~17 or 18Hz, while I don't had at hand DATSv3 nor a diy impedance jig, I've tested with an adhesive tape and cranked up the amplifier and used a tone generator, so far when the tone generator was set to 17Hz, the woofer drop excursion dramatically and everything in the room was insanely shaking and I feel the high pressure, I didn't hear any port noise/compression when testing so far.
Complete step by step build log HERE
Some build images:
The triple front baffles.
Deluxe 6 prong T-Nuts epoxied.
The Ankh shaped braces and port support.
Gluing started next to a 16oz glue bottle for size reference, I've used my favorite glue TB3.
The braces in place.
Interior view of the port supporters embedded on the braces.
Spreading a generous amount of glue per brace and top/bottom walls.
Internal preview of one box almost ready, back wall non yet glued.
Port dry-run test before sealing it with RTV and gluing the back wall.
Port top/brace clearance.
Port being sealed with 100% RTV.
Applying few turns of Scotch blue tape for port tighten.
Port being evenly pushed gently with a small piece of wood scrap and a rubber hammer.
Port back view.
Complete step by step build log HERE
For reference the mains build log HERE
Regards
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Build images continuation:
Really sorry for the room mess as is still unfinished.
I will post some quick response measurements asap.
Regards!
Really sorry for the room mess as is still unfinished.
I will post some quick response measurements asap.
Regards!
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Very impressive sub build!
But to be honest with you, if I had "access" to this room, I would take away the seos horn speakers 🙂
But to be honest with you, if I had "access" to this room, I would take away the seos horn speakers 🙂
Hi drjlo, the horns are FaitalPro LTH102 paired with HF10AK drivers and they sound really smooth.
However I've been thinking on the Fostex T96A top mount super tweeters or similar for the airy top octave or maybe I build a pair.
Regards
I can't get over the size of those boxes compared to your other speakers! What is in your mains, a 12"? Looks about the size of the dustcap of your subs😀
Very nice build, love the attention to detail on the inside (which no one will ever see) and the crazy big port. Only thing I would have added is a brace from the bottom to the top, connecting all the braces in the middle. Enjoy your work, the next upgrade is to 24", which I don't think you will quickly need (but you probably thought the same when you had 18"😀)
Very nice build, love the attention to detail on the inside (which no one will ever see) and the crazy big port. Only thing I would have added is a brace from the bottom to the top, connecting all the braces in the middle. Enjoy your work, the next upgrade is to 24", which I don't think you will quickly need (but you probably thought the same when you had 18"😀)
Hi, thanks for the input, the Mains mid/woofers are the 10" PRV 10W650A-8.
So far after pushing this 21" subs between 16~20Hz, I was completely happy that they don't rock nor the top wall did flexed, I even put an allen wrench and it didn't move, though I have to note that the top wall is double 5/8" and only put about ~1500W out of the old Samson S2000 when bridged as the door, windows etc. was rattling enough.
P.S. I'm running each sub now on each CH from the amplifier so they will get a max of 1000W, so if I ever get the iNuke NX6000 will be for the power efficiency.
Regards
Here are some Quick measurement I've made this morning.
Since taking on-axis measurements is quite not so useful on subwoofers, this time I've took them at the listening position and looks like I have great room gain in the low end despite the room being almost square and cluttered, hopefully the measurement may look ok.
WinISD RAW prediction(21SW152-4, ~9.5FT^3, ~19Hz tune):
Quick measurement on the LP without and with light PEQ(0~250Hz sweep):
Quick measurement on the LP with light PEQ and smoothed(0~250Hz sweep):
The subs are crossed at 60Hz LR4, with an high-pass of 16Hz BW4.
Regards
Since taking on-axis measurements is quite not so useful on subwoofers, this time I've took them at the listening position and looks like I have great room gain in the low end despite the room being almost square and cluttered, hopefully the measurement may look ok.
WinISD RAW prediction(21SW152-4, ~9.5FT^3, ~19Hz tune):
Quick measurement on the LP without and with light PEQ(0~250Hz sweep):
Quick measurement on the LP with light PEQ and smoothed(0~250Hz sweep):
The subs are crossed at 60Hz LR4, with an high-pass of 16Hz BW4.
Regards
Loudspeaker pornography! You have inspired me to restart my dining-room sub (I have no man cave). I have two B&C 21" knock-offs crying out to be installed.
Paul
Paul
Hi, also wish I had my own man cave for dedicated audio, between good luck with your future 21's project.
Hi thanks for your reply in regards to the graphs scale, indeed those are scaled up to 180dB which is rather insane and indeed hard to read despite they may look more linear, just got excited about the look but after scaling to 120dB(10dB/div) indeed shows that the room extension is just ok to about ~15Hz and not 10Hz as I've mentioned earlier.
Here are the REW graphs scaled to 120dB(10dB/div):
Thanks again for the tip regarding the scale.
P.S. I hope to deal soon with the room peak/nulls as the room is almost square and less than optimal, maybe its time to play with the Auto-EQ feature on the dbx.
Regards
Thanks for re-plot. Impressive for FR to look that good right down to 20 Hz and below even before EQ.
What smoothing? Many folks use "12".
If experimenting, I'd try moving the subs around. If speakers are clean and XO slope sharp, no loss of image on music as high as 120 Hz or more. And mids then become moveable too.
THD plot?
What smoothing? Many folks use "12".
If experimenting, I'd try moving the subs around. If speakers are clean and XO slope sharp, no loss of image on music as high as 120 Hz or more. And mids then become moveable too.
THD plot?
Hi, the previous smoothed plots where 1/6, but I will post the 1/12 plot here as recommended, followed by the THD plot, though I'm still learning more about REW in this regards.
Also I have to note that I was using a Dayton EMM-6 microphone and an old Alesis MultiMix4 USB mixer for taking the measurements and I believe the USB card has a little early roll-off below 20Hz but I have to re-check and maybe re-calibrate it.
Will had some time to take the whole system, the 21" subs plus the 10" midwoofers to see how the plots compares in regards peaks/valleys, unfortunatelly due the messy room clutter and the added furniture, can't move the subs around but rather play with AutoEQ or Dirac if I ever get the NAD C658.
You are one super poster. Thanks.
THD on my screen is mostly below "the horizon". Easy with REW to shift up.
EQ (esp DSP) can do harmful things to distortion plots. So good to post runs for the un-EQ'ed speaker.
I use an EMM with a disk-jockey mic mixer. The individual EQ, the errors in cards and even headphone amps in laptops (such as my quality MacBooks) are so trivial, hardly worth fussing about, down quite low. Most measurements are iterative anyway.
If you plot the speaker impedance, it will give you a definitive picture of the motion of the cone (below 1kHz). Absolute figure not important although you can plot a 10-Ohm resistor as a benchmark. That is quite meaningful for folks who build BR boxes like yours.
You know the joke about the father of twins that only bothered to keep one photo in his wallet.
Ben
THD on my screen is mostly below "the horizon". Easy with REW to shift up.
EQ (esp DSP) can do harmful things to distortion plots. So good to post runs for the un-EQ'ed speaker.
I use an EMM with a disk-jockey mic mixer. The individual EQ, the errors in cards and even headphone amps in laptops (such as my quality MacBooks) are so trivial, hardly worth fussing about, down quite low. Most measurements are iterative anyway.
If you plot the speaker impedance, it will give you a definitive picture of the motion of the cone (below 1kHz). Absolute figure not important although you can plot a 10-Ohm resistor as a benchmark. That is quite meaningful for folks who build BR boxes like yours.
You know the joke about the father of twins that only bothered to keep one photo in his wallet.
Ben
Hi Ben, thanks alot for the insights and tips in regard the measurement on THD, I admit I have lots to learn in this camp so far.
I'm not sure about the distortions may look average or awful. but I agree about EQ/PEQ may add unwanted results, plus my used old-school amplifier a Samson S2000 from the yeah 1999~2000, that I haven't re-caped the electrolytic's yet may be another source of distortion as well?
Regards
I'm not sure about the distortions may look average or awful. but I agree about EQ/PEQ may add unwanted results, plus my used old-school amplifier a Samson S2000 from the yeah 1999~2000, that I haven't re-caped the electrolytic's yet may be another source of distortion as well?
Regards