I'd like to add some subs to my recording/mixing setup and am looking for some guidance.
-Looking to build a pair of clean, accurate subs, with good low extension, somewhere in the neighborhood of $250 per sub
-I want something relatively simple to build
-I'll be using these -- paired with a set of ProAc 100s powered by an Adcom gfa 555mkII -- to mix records
-I'm in an acoustically treated basement space (24x18x8) and don't need to energize the whole space: I sit about 3 feet from the speakers, in the front 1/3 of the room, and rarely work at higher than 85db. Occasionally I'll crank it to check for excitement, but my working levels are generally between 60-85db
-I've got a little room/system bump at 100hz, and a null around 60hz Other than that, low end response is pretty even
-The ProAcs are rated down to 40hz, but my experience is that things drop off below ~60hz pretty quick
-I have a Crown cdi1000 amp that I'd like to use for power for the subs: 700wpc@2 ohms, 500wpc@4ohm, 275wpc@8ohm (http://www.crownaudio.com/media/pdf/amps/139681.pdf)
-I'll be using my DAC/software to handle crossover/eq duties
-I'm on a mac and don't have a windows license, and so haven't been able to use winISD, boxnotes, or any of the excel spreadsheets, so if anyone's got any specific designs or can point to mac software I can use, that'd be a bonus
-Again, they don't need to be loud or have a ton of impact. I mostly just need an accurate, tight/dry representation of what's going on in the lowest two octaves, and to relieve the proacs of some of the low frequency duty
At the moment I'm considering a stereo pair of open baffle subs with either:
4 eminence alpha-15s, 2 per side, wired in parallel
or
4 dayton audio IB385-8 15s, same as above
or
2 AE IB15s, 4ohm version, one per side
or
2 or 4 Peavey 15" DVC professional woofers wired for 4 ohms a side
using either H or U or Linkwitz Dipole sub enclosure
Any input, cautionary tales, direction etc. welcome.
Thanks!
-Looking to build a pair of clean, accurate subs, with good low extension, somewhere in the neighborhood of $250 per sub
-I want something relatively simple to build
-I'll be using these -- paired with a set of ProAc 100s powered by an Adcom gfa 555mkII -- to mix records
-I'm in an acoustically treated basement space (24x18x8) and don't need to energize the whole space: I sit about 3 feet from the speakers, in the front 1/3 of the room, and rarely work at higher than 85db. Occasionally I'll crank it to check for excitement, but my working levels are generally between 60-85db
-I've got a little room/system bump at 100hz, and a null around 60hz Other than that, low end response is pretty even
-The ProAcs are rated down to 40hz, but my experience is that things drop off below ~60hz pretty quick
-I have a Crown cdi1000 amp that I'd like to use for power for the subs: 700wpc@2 ohms, 500wpc@4ohm, 275wpc@8ohm (http://www.crownaudio.com/media/pdf/amps/139681.pdf)
-I'll be using my DAC/software to handle crossover/eq duties
-I'm on a mac and don't have a windows license, and so haven't been able to use winISD, boxnotes, or any of the excel spreadsheets, so if anyone's got any specific designs or can point to mac software I can use, that'd be a bonus
-Again, they don't need to be loud or have a ton of impact. I mostly just need an accurate, tight/dry representation of what's going on in the lowest two octaves, and to relieve the proacs of some of the low frequency duty
At the moment I'm considering a stereo pair of open baffle subs with either:
4 eminence alpha-15s, 2 per side, wired in parallel
or
4 dayton audio IB385-8 15s, same as above
or
2 AE IB15s, 4ohm version, one per side
or
2 or 4 Peavey 15" DVC professional woofers wired for 4 ohms a side
using either H or U or Linkwitz Dipole sub enclosure
Any input, cautionary tales, direction etc. welcome.
Thanks!
In case anyone's checking in:
I ordered a pair of the Eminence Alphas to start.
Going to put them in H frames after reading this:
http://www.quarter-wave.com/OBs/U_and_H_Frames.pdf
I ordered a pair of the Eminence Alphas to start.
Going to put them in H frames after reading this:
http://www.quarter-wave.com/OBs/U_and_H_Frames.pdf
Lots of theoretical stuff there and zilch practical measurement.
The main reason people use dipoles is because they like their ambience-soaking sound (or in the case of ESLs, the technology forces them to use a dipole shape, pretty much). In as much as I think there's no "sound" to a sub, ambience or otherwise, there's no good reason to use a dipole*.
Ben
*OK, another reason is to introduce heterogeneity to counter-act room influences.
The main reason people use dipoles is because they like their ambience-soaking sound (or in the case of ESLs, the technology forces them to use a dipole shape, pretty much). In as much as I think there's no "sound" to a sub, ambience or otherwise, there's no good reason to use a dipole*.
Ben
*OK, another reason is to introduce heterogeneity to counter-act room influences.
Maybe not on that page specifically, but MJK is very well known for correlating all his software with actual measurements. All of it, the transmission lines, the OB stuff, even his stuffing routine is extremely well regarded as being accurate and it's all based on correlation to actual measurements and backed up by thousands of independent measurements from users of his software.
Caseyblu's Eminence H frames will work exactly as simulated, keeping in mind that the software can only simulate the three nearest boundaries. But the native response including the three nearest boundaries will work exactly as predicted.
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You will be very happy with them, assuming you understand they won't have the same spl as a closed box. Lots of people on this forum have built these and love them.
I'll try and post some measured frequency response info when I get them all set up.
Also, regarding heterogeneity and room influences are you talking about Geddes's multi sub setups? Or the idea that dipoles have less room interaction than other subs?
This may already be explored to death on this forum, folks can feel free to point me to good threads/links, but I'm still fuzzy on the room interaction aspect of dipoles. Aren't low frequency waves pretty omnidirectional, regardless of the radiating source? To put it another way: if you've got a room mode at 37hz, how does a dipole playing that freq excite the room response less than a monopole? Minimal room interaction makes dipoles an attractive option for people mixing in imperfect rooms with tricky modal responses, I'd really like to know more about this.
This is great to hear. I have a good feeling about them, and yes, not expecting too much output, I just want to be able to hear what's going on down there, and take some of the low end load off the proacs.
I have a pair or JBL 4411s that I'm going to rebuild the crossovers on, I'm thinking maybe down the road I'll do a sealed, or horn, sub to pair with these and they can be my loud/fun speakers.
I dislike the idea of mixing music on "weird" setups like electrostatics or unusual speakers...including open baffle subs. Of course, whatever you mix on is never gonna exactly match the customers playback, but mixing with something that has an unusual sound could lead to an odd sounding record.
I'm really not sure what anyone gains with an open baffle sub. Yeah, maybe reduction of some kind of room interaction. But at your mixing position, I think the response would be more uneven than a conventional sub at least at upper bass frequencies, as the front and rear waves interfere. If the crossover is low maybe that won't matter as much. However you will need a lot more power to equalize the response falling off due to cancellation.
I'm really not sure what anyone gains with an open baffle sub. Yeah, maybe reduction of some kind of room interaction. But at your mixing position, I think the response would be more uneven than a conventional sub at least at upper bass frequencies, as the front and rear waves interfere. If the crossover is low maybe that won't matter as much. However you will need a lot more power to equalize the response falling off due to cancellation.
These are great points to consider. I'll abandon the OB sub idea pretty quick if it doesn't work in practice. You're right, the real test is how well mixes translate.
I'll be crossing these over to the ProAc 100s somewhere between 80-120hz. The H frame design, according to the MJK whitepaper, is theoretically pretty flat from there down to a little under 40hz with a -3db at 28hz. I'll be measuring low end response at mix position and checking for low end translation on other systems before doing any serious work. I'll also spend a good deal of time getting to know the OB bass sound using some trusted reference material. Hopefully all this will keep me out of trouble.
Do you have any specific recommendations, based on the laundry list from my original post, that I should consider if the open baffles end up a bust? I'm still considering some kind of sealed sub or horn design in the future.
+1 for the wise thoughts well expressed by head_unit.
If you have the real-estate, you can't beat a sealed box (or leaky sealed box if space is tight), esp. for those nice drivers. No calculation is needed: the bigger the box the better, simple as that.
BTW, makes no sense to rebuild a crossover when you can get an electronic one (analog or digital) cheap from Behringer.
Ben
If you have the real-estate, you can't beat a sealed box (or leaky sealed box if space is tight), esp. for those nice drivers. No calculation is needed: the bigger the box the better, simple as that.
BTW, makes no sense to rebuild a crossover when you can get an electronic one (analog or digital) cheap from Behringer.
Ben
This is great news. If I can just build sealed enclosures for these drivers if the H frames suck, I'll be pretty happy.
I'll be using software (metric halo's mio console) and my multi out DAC to handle crossover duties.
I'd appreciate mixes that were done on optimized playback systems. Too bad a lot of popular music sounds good on a cheap car radio, but when you put it on your audiophile system you wonder why you bought it. Playing with subwoofer adjustments is a constant because of this lack of standard target. If you do OB as a reference, please start with a total Q below .71, and preferably f3 under 30 Hz. Unfortunately that rules out the alpha 15s. The Dayton IBs will definitely get you started.
I was actually leaning towards Dayton IBs, one per side, but thought it would be bad to under-power them. At 8ohms my amp puts out 275wpc, the Dayton IBs are rated at 350watts program. I also thought 2 per side (wired parallel for 4ohms @ which I can do 500wpc) might be a little much and it would certainly have put me over-budget after materials.
I thought higher total qs were better for this application. Can you elaborate on the choice of total q lower than 0.71?
And, if you could pick any sub setup in the $500 range, given the constraints/goals detailed in my original post, what would it be?
For me, a good mix is one that sounds as the engineer intended on as many different systems as possible, earbuds to PA mains and everything in between. I'm here trying to make my setup better towards that end.
Final system q is what matters.
MJK showed a way to get a desirable final system q with very little effort by using a high q driver. If you have dsp available you can use any drivers you want as long as they have enough displacement to meet your spl goals and measurement capabilities to get it right.
Higher Q is better for efficiency at resonance, but that's all. If you start with a driver near Qts .7 and a satisfactory rolloff point, EQ may not even be required outside of the 6dB octave OB compensation. Lower Q in the speaker can be better for sound (IS better for sound at high levels) since you're usually dealing with a bigger motor, but unless you want to add series resistance to raise the Q or use an amplifier with adjusted output impedance, you'll probably need extra amplifier power to pull up the bottom.
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To add:
Using series resistance or high amplifier impedance to tune the Q of OB/IB woofers is cool because it lets you use any speaker with a Q lower than you want, provided that the rest of the parameters match. That setup is also beneficial not because you really want a bigger woofer motor than you need so you can look at it, but so you can give it much smaller drive than it is built to handle before causing too much distortion. IB is cool because it gets rid of that 6dB/oct rolloff and the EQ that OB requires.
Using series resistance or high amplifier impedance to tune the Q of OB/IB woofers is cool because it lets you use any speaker with a Q lower than you want, provided that the rest of the parameters match. That setup is also beneficial not because you really want a bigger woofer motor than you need so you can look at it, but so you can give it much smaller drive than it is built to handle before causing too much distortion. IB is cool because it gets rid of that 6dB/oct rolloff and the EQ that OB requires.
Final system q is what matters.
The Alpha motor is plenty strong to do what needs to be done. You can use a bigger motor and a more expensive driver to do the same job but that's up to you.
Be very careful if you want to play with series resistors. You could start a fire unless you use resistors with massive power handling capacity. Series resistance is ok for little fullrange speakers than can only do 1 or 2 watts within xmax, but it's an entirely different matter to put resistance in series with a subwoofer. It's usually very highly discouraged. DSP is a much better option.
There's an easy way and a hard way to do this. MJK has shown the easy way.
The Alpha motor is plenty strong to do what needs to be done. You can use a bigger motor and a more expensive driver to do the same job but that's up to you.
Be very careful if you want to play with series resistors. You could start a fire unless you use resistors with massive power handling capacity. Series resistance is ok for little fullrange speakers than can only do 1 or 2 watts within xmax, but it's an entirely different matter to put resistance in series with a subwoofer. It's usually very highly discouraged. DSP is a much better option.
There's an easy way and a hard way to do this. MJK has shown the easy way.
I use a Dayton PA460 sealed in a 7 cu.ft. box with a 2 ohm 100 watt resistor in series with it and a 500 watt amplifier in a 3-way bass guitar rig, mainly because I haven't yet finished the switching amplifier with load current feedback . I've never had to get the resistor warm at practice. You can start a fire with a 1/4 watt resistor in a 5 watt circuit.
I know where the rest of the Q argument goes.. Fs of 41Hz and Xmax of 3.8mm is not bad for a cheap 15" speaker, but I wouldn't put it in a studio. I've thought about using them on either side of my bed for some music to go to sleep by.
I know where the rest of the Q argument goes.. Fs of 41Hz and Xmax of 3.8mm is not bad for a cheap 15" speaker, but I wouldn't put it in a studio. I've thought about using them on either side of my bed for some music to go to sleep by.
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If I were building woofers in the above situation, I'd build 2 small towers with four 8 inch or 6.5 inch Peerless nomex cone woofers in each, closed box, with active EQ to make them acoustically flat down to 30HZ (where your ears will be), and a 4 pole xover somewhere between 80HZ and 200HZ, depending on what you're crossing them over to.
The advantage of two towers is that it spreads out the emission of the bass frequencies on all three axis, thereby reducing the room acoustics effects. Smaller drivers have tighter and cleaner bass. There's less conducted resonance in the cone itself and less mass. These Peerless drivers are reasonably priced ( $50 - $80 at madisound or Parts Express), and have very well vented spiders and pole pieces. I have the 6.5 inch versions and love them. I'd series-parallel the wiring to get back to 8 ohms as seen by the poweramp. There are free programs on the web that will calculate the box internal dimensions for you based on all the specs that come with the woofers.
Mixing music should be done with not just good speakers, but very good fidelity at your ears. Room acoustics are a very big deal in the real world. Any system that doesn't take room acoustic effects into account, is meager.
The advantage of two towers is that it spreads out the emission of the bass frequencies on all three axis, thereby reducing the room acoustics effects. Smaller drivers have tighter and cleaner bass. There's less conducted resonance in the cone itself and less mass. These Peerless drivers are reasonably priced ( $50 - $80 at madisound or Parts Express), and have very well vented spiders and pole pieces. I have the 6.5 inch versions and love them. I'd series-parallel the wiring to get back to 8 ohms as seen by the poweramp. There are free programs on the web that will calculate the box internal dimensions for you based on all the specs that come with the woofers.
Mixing music should be done with not just good speakers, but very good fidelity at your ears. Room acoustics are a very big deal in the real world. Any system that doesn't take room acoustic effects into account, is meager.
I'm not really an OB fanatic, but OB is what the thread is about, and there is an interesting application of OB speakers that Really Does get rid of room mode concerns, and that's a very near field setup. With just a meter behind the speakers and a meter from them to you it's possible to get flat bass to 30 at your ears with 10's and just about nothing as you walk away. Just put your DAW monitor between the speakers and you're good to go. Suddenly you don't need more than 100W of power or kilobuck drivers for the woofer. You do still need the cancellation slope filter. The rest of the band doesn't need to be OB.
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I'm not a recording engineer so I guess my opinion doesn't count for much but...
I've seen a bunch of studio monitors. Most of them use really tiny little drivers as woofers and a lot of them use phase inversion at relatively high frequencies to create bass, with all the problems that come with that. A lot of them don't have anything even near flat response. And I won't even get into the room considerations, but suffice to say that the room must be considered no matter what speakers you choose to use. (Your point about extreme nearfield use is a good one.)
As far as I know there's no absolute standard for studio monitors and MJK's project is pretty inexpensive and well regarded. If the OP doesn't like it he can move on without breaking the bank. Everything else that's been proposed is quite expensive in comparison. If the OP already has DSP the other options are more feasible though.
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