My new build is a pair of open baffles with pro drivers - 15" JBL and horn.
This is my first OB and I wasn't sure it would work at all.
I've been running a variety of horns for a while, ending up with big 2360 butt-cheeks, which served me very well for several years. Then last month it seemed like a good time to get rid of all that stuff and try something new. But without buying a lot of new drivers, since I'm well stocked with pro gear - a few 15s, a couple 12" EVs, some 1" and 2" compression drivers, and so on.
Back in ancient history, some of the best things I heard were Quad ESLs, and Celestion SL6000 dipole woofers (unfortunately not together...!). The big system was loud and precise but the bass was never right, always boomy. (My listening room is an attic with low sloped ceilings).
So this all started literally with open drivers on the floor. They actually sounded amazing. So for practicality and aesthetics I built some nicer oak baffles, which I'm quite pleased with. Starting this thread to write something about my approach, and hear from your experience on better ways to go about this.
A couple pictures attached, and more here.
This is my first OB and I wasn't sure it would work at all.
I've been running a variety of horns for a while, ending up with big 2360 butt-cheeks, which served me very well for several years. Then last month it seemed like a good time to get rid of all that stuff and try something new. But without buying a lot of new drivers, since I'm well stocked with pro gear - a few 15s, a couple 12" EVs, some 1" and 2" compression drivers, and so on.
Back in ancient history, some of the best things I heard were Quad ESLs, and Celestion SL6000 dipole woofers (unfortunately not together...!). The big system was loud and precise but the bass was never right, always boomy. (My listening room is an attic with low sloped ceilings).
So this all started literally with open drivers on the floor. They actually sounded amazing. So for practicality and aesthetics I built some nicer oak baffles, which I'm quite pleased with. Starting this thread to write something about my approach, and hear from your experience on better ways to go about this.
A couple pictures attached, and more here.
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You're on the right path and the baffles look nice. 
For a few years I ran a 15" woofer topped with an Altec horn on OB. I liked it a lot, so did a lot of friends. Getting the crossover right was a big learning experience, tho.
For a few years I ran a 15" woofer topped with an Altec horn on OB. I liked it a lot, so did a lot of friends. Getting the crossover right was a big learning experience, tho.
Open speakers on the floor actually did sound good -- after adding compensation for the dipole rolloff.
Here's the RC network I put together. It's basically a fairly heavy bass shelving filter. Additionally for safety I have a 20Hz highpass (digital), because although the XMax on these woofers is fairly decent, I have lots of electronica with subsonic weirdness and playing it too loud would be an expensive mistake.
This setup with no baffle was a real eye-opener. The bass was there, but unobtrusive and smooth. The overall effect was quite enchanting.
Here's the RC network I put together. It's basically a fairly heavy bass shelving filter. Additionally for safety I have a 20Hz highpass (digital), because although the XMax on these woofers is fairly decent, I have lots of electronica with subsonic weirdness and playing it too loud would be an expensive mistake.
This setup with no baffle was a real eye-opener. The bass was there, but unobtrusive and smooth. The overall effect was quite enchanting.
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I'm with you on the simple no baffle effect. I've been fiddling around with a naked 4-way for about a year now and find it quite nice. I really think the "ideal" would be a 4-way naked with sealed sub(s) .... below 50-60hz. Don't have to worry about hurting any of the naked drivers that way.
I don't use mini DSP for my active set-up ... rather an older pro (EV) DSP. There are fewer EQ functions so I had to pay closer attention to each drivers natural response and use that to an advantage with the crossover points. EQ'ing the heck out of they're response(s) didn't appeal to me sonically. The sum always had a "forced" sound to me.
I don't use mini DSP for my active set-up ... rather an older pro (EV) DSP. There are fewer EQ functions so I had to pay closer attention to each drivers natural response and use that to an advantage with the crossover points. EQ'ing the heck out of they're response(s) didn't appeal to me sonically. The sum always had a "forced" sound to me.
Some measurements of the final speaker, from listening position. These have 1/48th octave smoothing applied, to hide some of the ragged spikes. The full-range combined measurement has a crossover at 1kHz.
There's something wrong with the top end; it's very rolled off. Later...
The bass is surprisingly flat, and strikingly free of any obvious room-mode suckout.
There's something wrong with the top end; it's very rolled off. Later...
The bass is surprisingly flat, and strikingly free of any obvious room-mode suckout.
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Thanks for the graphs. I have to say that I am VERY surprised at the bass response. How far back in the mic? Is that done using your line level EQ?
Regarding the rolled off treble- your midbass is too efficient. I suspect you're getting reinforcement from the floor to a higher frequency than one might think. Providing CD eq can take those 110dB comp drivers down to mid-90s very quickly- of course, they're still crazy efficient, just not crazy sensitive because of the filter.
Details on XO?
Details on XO?
Microphone was just forward of the usual listening position, 10 feet from the speakers. In the picture, that's a foot above the laptop.
The picture reminds me. Every time I go up to the attic, one of the great things about these speakers is they smell really great. Tung oil finish. 😀
The bass is a surprise still. It goes deep but in a completely different way to anything I'm used to.
The only EQ is that R-C network after the bass DAC, and a resistive L-pad on the compression drivers to manage their level, and a 20Hz highpass to protect the drivers.
I'm using a NanoDigi for crossover duties and the highpass protection, fed S/PDIF from a Squeezebox Transporter. When I first started using the nanoDigi, it didn't sound at all great at 44kHz, which I attributed to ASRC (rightly or not, I can't really tell). So I'm upsampling everything to 96k with sox first (rate -v -s -I). CPU is cheap!
Crossover frequency is 1kHz right now, and the slopes are 48dB/octave Linkwitz-Riley just because they're the steepest. The bass is delayed by 23cm (acoustic distance between the bass and tops, based on the impulse response measurements). I love the flexibility of being able to dial in delay plus off-the-shelf crossover at whatever frequency sounds right, and haven't even tried to go deeper into custom biquads or whatever.
The picture reminds me. Every time I go up to the attic, one of the great things about these speakers is they smell really great. Tung oil finish. 😀
The bass is a surprise still. It goes deep but in a completely different way to anything I'm used to.
The only EQ is that R-C network after the bass DAC, and a resistive L-pad on the compression drivers to manage their level, and a 20Hz highpass to protect the drivers.
I'm using a NanoDigi for crossover duties and the highpass protection, fed S/PDIF from a Squeezebox Transporter. When I first started using the nanoDigi, it didn't sound at all great at 44kHz, which I attributed to ASRC (rightly or not, I can't really tell). So I'm upsampling everything to 96k with sox first (rate -v -s -I). CPU is cheap!
Crossover frequency is 1kHz right now, and the slopes are 48dB/octave Linkwitz-Riley just because they're the steepest. The bass is delayed by 23cm (acoustic distance between the bass and tops, based on the impulse response measurements). I love the flexibility of being able to dial in delay plus off-the-shelf crossover at whatever frequency sounds right, and haven't even tried to go deeper into custom biquads or whatever.
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Are you sure you want such steep slopes? If I remember correctly the experts ( Linkwitz, Bruno Putzeys and others ) use 24db/oct as guideline since steeper filters have a significant problem with pre ringing off axis. Unless you are really pushing the drivers to their limits then 24dB/oct should be enough anyway =)
I think you're probably right. Also 1k is at the low end, and could comfortably go higher. The raw response for each driver overlaps plenty far enough.
Do you know any specific things to listen for? (I've not managed to distinctly hear pre-ringing artifacts before).
Do you know any specific things to listen for? (I've not managed to distinctly hear pre-ringing artifacts before).
Yes, your speaker placement works as a gigantic bass horn! With that arrangement and dipoles moving the seaker just inch or two should make very big changes in the response.
Looks like you are measuring with REW and the preset 500ms gating and Tukey 0,25. It collects most of your room reflections and reverberations, and mimics the spl/F balance that you sense with ears. Using shorter measuring distance and shorter gate (try 6, 12, 20, 60, 120ms by IR Windows, use the same *.mdat) gives you better the performance of the speaker without room effects.
A speakers own response and how it works in the room are both important per se, but we must identify each to undestand what is happening.
Please consider buying a minidsp 2x4! It is a wonderful tool with these homebrew experimentals. Delay setting is a very important feature of it!
Looks like you are measuring with REW and the preset 500ms gating and Tukey 0,25. It collects most of your room reflections and reverberations, and mimics the spl/F balance that you sense with ears. Using shorter measuring distance and shorter gate (try 6, 12, 20, 60, 120ms by IR Windows, use the same *.mdat) gives you better the performance of the speaker without room effects.
A speakers own response and how it works in the room are both important per se, but we must identify each to undestand what is happening.
Please consider buying a minidsp 2x4! It is a wonderful tool with these homebrew experimentals. Delay setting is a very important feature of it!
Pano - that looks right, but it sounds much stronger than it sims. I could be wrong about the amp's input impedance. Some time in the next days I'll measure the system without the compensation network, which should be quite interesting.
Sure the corner helps. I don't think it's really horn-loading, but getting bass to sound decent in this room has been problematic with normal speakers.
Juhazi, many thanks for the tip about windowing in REW. That really helps. As soon as I looked with a short window, it's obvious the tops are inverted; there's a deep null at 1k, with a 5ms window over the impulse response, which surely means bass and top canceling each other at crossover.
I though the nanodigi was roughly the digital-only equivalent of minidsp 2x4. For a while I was using a DriveRack 260, but this is much better sounding. I don't need more DACs (really!) and like to do crossovers in digital without any additional steps.
Sure the corner helps. I don't think it's really horn-loading, but getting bass to sound decent in this room has been problematic with normal speakers.
Juhazi, many thanks for the tip about windowing in REW. That really helps. As soon as I looked with a short window, it's obvious the tops are inverted; there's a deep null at 1k, with a 5ms window over the impulse response, which surely means bass and top canceling each other at crossover.
I though the nanodigi was roughly the digital-only equivalent of minidsp 2x4. For a while I was using a DriveRack 260, but this is much better sounding. I don't need more DACs (really!) and like to do crossovers in digital without any additional steps.
If you have DACs with SPDIF input then yes, the nanoDIGI is the way to go. The UI on them MiniDSP stuffs is criminally good too, a pleasure to use =)
It is obvious that inguz's speaker placement and dipole bass actually reinforces the backwave at low frequences so much that it dominates in long gate measurements. Then the phase becomes a problem at transition range to where direct sound dominates.
This leads the amateur diyer to trouble when looking at responses. Perhaps the best speaker arrangement would be to find that transition area and use a backwars firing monopole bass below it, with sharp xo. And a second monopole or cardioid from there up. Then distance/delay/phase matching should be set spot-on.
This is in practical sense quite impossible to do. I guess the best practise is to do some testing and measurements to clarify different aspects. Perhaps there is a simulation or a formula to help with this. Then, this very special acoustic environment must be accepted as such and be fine tuned by ear to give most pleasant sound!
I have been playing with a partly dipole speaker a lot lately. I love the lifelike sound the deliver with solo instruments, voice and well recorded orchestral music. The backwave fills the room with reverberating sound, and when I walk around the music/sound is very much like real instuments being played. This is very true specially if only one speaker is playing eg. cello solo! Try this!
There are many people who don't like this reverberance and if we use analyses like STI or MTI a dipole will lose the battle. But this is how a dipole/ob works and sounds - it really is a different animal!
This leads the amateur diyer to trouble when looking at responses. Perhaps the best speaker arrangement would be to find that transition area and use a backwars firing monopole bass below it, with sharp xo. And a second monopole or cardioid from there up. Then distance/delay/phase matching should be set spot-on.
This is in practical sense quite impossible to do. I guess the best practise is to do some testing and measurements to clarify different aspects. Perhaps there is a simulation or a formula to help with this. Then, this very special acoustic environment must be accepted as such and be fine tuned by ear to give most pleasant sound!
I have been playing with a partly dipole speaker a lot lately. I love the lifelike sound the deliver with solo instruments, voice and well recorded orchestral music. The backwave fills the room with reverberating sound, and when I walk around the music/sound is very much like real instuments being played. This is very true specially if only one speaker is playing eg. cello solo! Try this!
There are many people who don't like this reverberance and if we use analyses like STI or MTI a dipole will lose the battle. But this is how a dipole/ob works and sounds - it really is a different animal!
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Sure? Can you provide such measurements made with dipoles? I'm asking because I thought that speech intelligibility has improved since I use dipoles. Just my subjective experience.
Rudolf
Kimmosto made STI/MTI analysis of Aino vs my ER18DXT room measurements with ARTA. There is no significant difference except above 3kHz where Aino is not dipole!
I was sure that Aino would be better, my ears said so. The better speakers Kimmosto shows are cardioids made by him. aku means after room treatment.
I was sure that Aino would be better, my ears said so. The better speakers Kimmosto shows are cardioids made by him. aku means after room treatment.
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Well, well. Room loading.
Here's the "compensated" (i.e. my first setup) versus "uncompensated", which is just unplugging the capacitor (so gain is higher, too). Crossover is still active for these, so they only make sense up to ~600Hz, but below that are a good representation of the listening-position response.
Without any treatment at all, the room loads the open baffle decently down to 70Hz. Just wow.
The woofer nearfield response (measured 10cm from cone) itself is flatter than flat. Link to raw impulse responses etc.
Here's the "compensated" (i.e. my first setup) versus "uncompensated", which is just unplugging the capacitor (so gain is higher, too). Crossover is still active for these, so they only make sense up to ~600Hz, but below that are a good representation of the listening-position response.
Without any treatment at all, the room loads the open baffle decently down to 70Hz. Just wow.
The woofer nearfield response (measured 10cm from cone) itself is flatter than flat. Link to raw impulse responses etc.
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