I'm contemplating building speakers with a giant horn on the front, and big wooferage, ideally out of sight on the back. They would be maybe 24" wide...meaning large enough to fit a 21" woofer, which are from $300ish at Parts Express.
Alternatives would be quad 10" or maybe quad 12" - ah it's good to have choices in this life!
What thoughts do you have about these alternatives? Particulary if the budget was kept at $300ish per 4x10 or 4x12? (But comments don't have to be limited to those scenarios, blurt anything that comes to mind!)
Alternatives would be quad 10" or maybe quad 12" - ah it's good to have choices in this life!
What thoughts do you have about these alternatives? Particulary if the budget was kept at $300ish per 4x10 or 4x12? (But comments don't have to be limited to those scenarios, blurt anything that comes to mind!)
18 inch is usually the sweet spot for price/performance as far as woofers for below 100 hz. We may need more information about what you are doing in order to make a smart choice.
A had 2 different subwoofers (push pull slot loaded f3 boosted at fs/tuning 27hz).
One was 2 x 18's with 4.3mm xmax.
Other was 4 x 12's with 8mm xmax.
The 2x18 moved thair air better, couldn't tell you why, more whomp, felt that way anyway.
My buddy has a theory about vortices, something about a better air leveraged having 2 larger circles than 4 smaller ones.
I would do push pull not matter sealed, ported, etc.
But..............
I only plan on 100w per driver for volumes.
2 x12 ppsl, i would do over a single 18", far cleaner, disappears better.
One was 2 x 18's with 4.3mm xmax.
Other was 4 x 12's with 8mm xmax.
The 2x18 moved thair air better, couldn't tell you why, more whomp, felt that way anyway.
My buddy has a theory about vortices, something about a better air leveraged having 2 larger circles than 4 smaller ones.
I would do push pull not matter sealed, ported, etc.
But..............
I only plan on 100w per driver for volumes.
2 x12 ppsl, i would do over a single 18", far cleaner, disappears better.
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Funny you should post that as I was just realizing that depending on cabinet height 2-3 15s or at least 2x18 would probably be viable, and the Parts Express 18 from $100.
My question was just general, but a particular project I'm dreaming of would literally have a big horn in front and woofer(s) hidden away. Ideally this would be on the back of the enclosure, which would require a horn and driver to go quite low, a woofer to have a robust power response, and the gods to smile on the slot loading happening against the walls behind. Failing that I suppose some kind of slots could be employed on the front, engendering other resonance problems. Basically I want to make something different looking.
I would get 4 woofers and build 2 woofers with a pair of woofers push-push.
Woofers almost always work better with 2+ and the active reactive force cancelation of push-push brings huge benefits.
I did build just this with 4 CSS SDX10 and i have 4 more woofers downstairs to do it again.
dave
Woofers almost always work better with 2+ and the active reactive force cancelation of push-push brings huge benefits.
I did build just this with 4 CSS SDX10 and i have 4 more woofers downstairs to do it again.
dave
Hmm, the force cancelling IS very attractive. That means firing out the side (unless I give in and have a woofer on the front). That is problematic as the L/R inside woofers, and both center woofers, would be slot loaded by immediately proximate cabinets. I guess if for serious listening I am moving the cabinets apart maybe that's not such a big deal...after all rear firing woofers will fire into a slot created by the wall behind.
I could also fire the woofers into slots but then the slot resonance is a problem, and the cabinet construction more complex and therefore more expensive. It would be cool to experiment with the slots by making angled and curved inserts and documenting that.
Any woofer, not matter which way the bass driver faces is omnidirectional.
We have used side-mounted woofers as high as 450Hz, but in a woofer the proximity of the woofers (ie significantly less than a quarter-wavelength in any of its passband), the 2 woofers act as one, and load the room a bit more evenly.
I don’y get your “slots”.
dave
We have used side-mounted woofers as high as 450Hz, but in a woofer the proximity of the woofers (ie significantly less than a quarter-wavelength in any of its passband), the 2 woofers act as one, and load the room a bit more evenly.
I don’y get your “slots”.
dave
+1
Another vote for push-push.
The benefit of force cancellation is so very huge, ime.
I running dual 18"s per side, drivers with 19mm xmax.
I dunno if they could toss a beer off them or not ...that vibration free ..
Push pull, slot has a function, get driver close (and protection from environment).
They need to be no more than 1/4 wavelength apart for 1 octave above the highest frequency when rolling off.
So you roll a sub off at 150hz, the drivers should be no more than 1/4 wavelength of 300hz, or 1129 / 300 / 4 = around 1'.
Why ?
How about a 30db reduction of the 1st harmonic distortion ?
PiSpeakers Forum - Push-pull versus shorting rings - Wayne Parham, June 21, 2006 at 16:18:33
Yea, the slot can resonate, my 4 x 12" probably rings near 250hz, but 100hz crossover, never heard it
2 x 12" or 2 x 18" crossing at 150hz, never heard a slot resonance either.
Push pull subwoofers are clean, like a servo distortion reducing velodyne subwoofer without the cost.
Yes, they can be a pain to build or replace drivers.
And dont think "well you are only leaving odd order harmonic distortion, that we know sounds bad".
It sounds great.
KEN KREISEL DXD-12012 Dual 12" Push-Pull Subwoofer - HomeTheaterHifi.com
Talking on distortion "try 0.7% thd+n at 25hz and 98db with most subwoofers, and you will see a similar number, but the decimal point will be moved one number to the right...... 30hz, 101db, 0.6% distortion ? No problem with the kreissel. No wonder movie and music studios use this subwoofer...... the answer to this equation is to buy one."
That is a seal pair of 12's.
I've had my plans on 2 x 390hf sealed, 400w into the pair, without skipping past driver's 14mm xmax.
1 driver would be f3 @30hz for 108db and f10 near 20hz for 102db.
So the 2 drivers, add 6 more db, plus all the distortion reduction for push pull.
They need to be no more than 1/4 wavelength apart for 1 octave above the highest frequency when rolling off.
So you roll a sub off at 150hz, the drivers should be no more than 1/4 wavelength of 300hz, or 1129 / 300 / 4 = around 1'.
Why ?
How about a 30db reduction of the 1st harmonic distortion ?
PiSpeakers Forum - Push-pull versus shorting rings - Wayne Parham, June 21, 2006 at 16:18:33
Yea, the slot can resonate, my 4 x 12" probably rings near 250hz, but 100hz crossover, never heard it
2 x 12" or 2 x 18" crossing at 150hz, never heard a slot resonance either.
Push pull subwoofers are clean, like a servo distortion reducing velodyne subwoofer without the cost.
Yes, they can be a pain to build or replace drivers.
And dont think "well you are only leaving odd order harmonic distortion, that we know sounds bad".
It sounds great.
KEN KREISEL DXD-12012 Dual 12" Push-Pull Subwoofer - HomeTheaterHifi.com
Talking on distortion "try 0.7% thd+n at 25hz and 98db with most subwoofers, and you will see a similar number, but the decimal point will be moved one number to the right...... 30hz, 101db, 0.6% distortion ? No problem with the kreissel. No wonder movie and music studios use this subwoofer...... the answer to this equation is to buy one."
That is a seal pair of 12's.
I've had my plans on 2 x 390hf sealed, 400w into the pair, without skipping past driver's 14mm xmax.
1 driver would be f3 @30hz for 108db and f10 near 20hz for 102db.
So the 2 drivers, add 6 more db, plus all the distortion reduction for push pull.
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Hmmm...so yes ideally you would have opposed push-pull for distortion and vibration cancellation. However if I try to cross over to a horn, that means something like 400-800 Hz. At that point, resonances in a slot are most likely not ignorable. And I'm not sure how I could do the push-pull...I guess if I had one driver on the front below the horn, and another at the back facing the same way. It would kind of waste some cabinet volume which I probably have enough of.
The bigger problem is it will look like a horn with a big woofer underneath; I'm dreaming to make something different looking. I've considered a vertical slot under the horn with woofers facing-that would look unique but is not push-pull. Or I could try to flip around and mount one woofer magnet into the cone space of the other however I suspect the resulting cavity would resonate a lot and quite possibly act as a significant unpredicatable lowpass filter.
I think you meant push-pull? Anyway it reminds me of my buddy deciding it would be cool to put an Oldsmobile engine in an El Camino. OMG what a nightmare, needed a custom driveshaft, stuff didn't fit...but when done, you could have mimicked the Lexus commercial stacking wine glasses on top. You could only tell the motor was running from the exhaust, and the rotating drive belt pulleys.
The question is, up to what frequency is a woofer truly omnidirectional? Such that if you put it on the BACK it still radiates towards the front. The slots, maybe this will help? (Forget the open baffle part). It's basically like a downfiring subwoofer except with a wooden enclosure wall instead of the floor. If you look in the slot you'd see the woofer(s).
The Slot Loaded Open Baffle Project Article By Nelson Pass
You can look djk.
He did a slot loaded klipsch belle horn 4 x 8" first to replace the 15".
Then made a ppsl pair of 12's loading a lascala i think, called it a bull nose.
He did a slot loaded klipsch belle horn 4 x 8" first to replace the 15".
Then made a ppsl pair of 12's loading a lascala i think, called it a bull nose.
One hell of an El Camino !
Push-push was correct. Clamshell like...
I tried the sub both as push-pull, and push-push.
THD wasn't really much of a difference between the two.
Whereas motor vent noise from push-pull with one coil hanging in the slot, was clearly worse with push-pull.
Here's a THD comparison at 125dB SPL /1m level.
I believe THD reduction with push-pull is a benefit with some drivers and not with others, depending on how well behaved they are at excursions. (i used bms 18n862 which are supposedly well behaved.)
And i think force cancellation is probably the big reason for building a PPSL (either way, push-pull or push-push)
The big thing about a PPSL sub (either way) is the key word sub.
They are not really meant for duty above sub range imo (say about 200Hz absolute tops),
due to the slot math Norman gave.
Plus, force cancellation becomes so much less of a issue above sub range anyway.
My dual 18"s have an 11" slot. You can see the slot boost in raw performance in transfers below...raw and processed shown.
As sound pressure is not function of speaker cone displacement, but cone acceleration, so distortion reduction is not so obvious with push pull configuration.
On page you linked can be seen that 2. harmonic is reduced significantly, but 4. is reduced only very little. Can be that for images 30 Hz is selected because it has big reduction on 2. harmonic but on other frequencies reduction is not significant?
Just as Nick McKinney said a couple decades ago, a crappy woofer will benefit from push-pull (those usually won’t have a pole-piece vent) and if decent woofers go push-push.
dave
Head_unit,
Using a two-way bass reflex multiple entry horn (BRMEH) between two slot loaded dual 10" woofers, you could build a three way cabinet 24" wide with crossovers in the 80 and 800Hz range, and also satisfy your "different-looking dream".
Art
Attachments
All for the side mount push-push with the motors clamped, BUT, my build I installed this morning confirmed reversing one driver, side by side, lowered the even harmonics a lot more than I expected for only a very small increase in odd. As they are behind a screen, the big ugly motor is not visible.
