I'm now searching for a good 2" driver that I need to couple with the 8" tractrix horn. The tractrix horn has a mounting thread of 1 3/8". Does someone have experience with the eminence psd2002?
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Building a superior 2x10 cab
- Thread starter Arjank
- Start date
Passinwind
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- Dec 3, 2003
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- Designer/Toaster Tech @ Passinwind Electronics
That's a 1" driver, not 2". Far from my favorite compression driver, but you may find it OK for the money if it's as cheap where you are as it is here.
I like the BMS neo compression drivers a lot, personally.
The exit is 1"but the voicecoil is 2".
So, what driver do you recommend for 1 3/8" mounting thread?
The price should be resonable and the driver should be able to handle a crossover point of 1.5khz.
So, what driver do you recommend for 1 3/8" mounting thread?
The price should be resonable and the driver should be able to handle a crossover point of 1.5khz.
Passinwind
I know nothing.
- Dec 3, 2003
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- Designer/Toaster Tech @ Passinwind Electronics
What is "reasonable?" The cheapest thread-on compression driver I like much is the BMS 4540ND. In the US they are currently running about $125, but they are also sometimes available used for around half that, give or take.
Note that I also use my cabs for synthesizer and other things that are far more demanding than bass guitar though. You can probably get by with something much cheaper and lower in sensitivity. Building a good padding network for the BMS was costly, and frankly the whole exercise is probably overkill for most bass players' needs.
I got mine for $917 delivered with The Perfect Bass 15% off Valentines Day sale. Saved almost $200!
- Nov 24, 2008
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- Owner & designer, AudioKinesis; Auth. mfg, Big E (Home Audio only)
Arjank, I like your design philosophy. My goals are similar, though I take a different path than the one you have outlined.
It looks to me like you are not intimidated by a challenge, and you intend to build a cabinet that is not only very high quality but also extremely flexible.
May I toss out an idea: Two 10's side-by-side will arguably still be fairly directional in the horizontal plane even with a 1.5 kHz crossover. Depending on what the frequency response curve of your 10" woofer looks like, you might consider building the cab as a "two-and-a-half way"; that is, rolling off one of the woofers an octave or two below the crossover point. This technique is used in some large studio monitors that have two big woofers side-by-side and a horn above them. The advantage is, running a single woofer up in the crossover region widens the radiation pattern, and that wider radiation pattern in turn allows you to push the crossover frequency north a bit to where it's easier on your compression driver.
Best of luck with your design!
Hi DukeLeJeune, thanks for getting more ideas rollin'. I'm aware of the fact that two 10" crossed at 1.5 will still have a narrower off-axis response then a single one, that is, in the horizontal or vertical plane just how I place the cab. I designed it as a wedge so you can put it on a large stage on the ground so you have like a personal monitor. On a larger stage you stand not as close to the cab as in a small venue so a bit of beaming is not a big problem then. In a small venue you can place it on it's side (e.g. on a stand) and then you have good horizontal off-axis response.
Building a two and a halfway may sound as the way to go but it's not. The problem is that you get phase shifting problems when you roll off one of the 10 inch woofers one octave earlier. This will create a major dip in de mid/bass region. I trade a slightly narrower off-axis response in one plane for that.
Each design has it's drawbacks and we have to live with that.
Remember, a regular 2x10 or 4x10 cab has a much narrower off-axis response because of the high crossover point.
I did some simulations (software) and did not get good results for the two and a half way system. The crossover will get way to complex, e.g you'll need to correct the 2nd impedance peak of the ported woofer that is crossed the lowest. Also, the inductor value will get very high so you need one with ferro material in it and thats not what I want because of the distortion it may generate.
The regular two way does however have a good off-axis response in the simulation, better then I thought. The crossover can stay pretty simple and I can use an air inductor (which does not generater any distortion).
Also, the two and a half way will cost me some efficiency.
In the picture you'll see the simulated frequency response of the 2 10" woofers in a 60liter enclosure. The red curve is the 30degree off-axis response.
The regular two way does however have a good off-axis response in the simulation, better then I thought. The crossover can stay pretty simple and I can use an air inductor (which does not generater any distortion).
Also, the two and a half way will cost me some efficiency.
In the picture you'll see the simulated frequency response of the 2 10" woofers in a 60liter enclosure. The red curve is the 30degree off-axis response.
Any idea/guess as to what this cab would cost ?
You could also look at some Bill Fitzmaurice designs.. the Jack 10 with 210 and the omni 12 210.
You could also look at some Bill Fitzmaurice designs.. the Jack 10 with 210 and the omni 12 210.
- Nov 24, 2008
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Agree that the crossover will be complex.
Here's a link to measurements of a home audio two-and-a-half way system:
Invalid Link Removed
Figures 3 and 4 are of interest.
Not trying to talk you into it; just trying to show that a two-and-a-half way system can work.
If you build it your self? Difficult to tell since the Oberton loudspeakers need to be imported to the US. But, I saw the export prices and they are pretty low so I guess it's worth to get them imported into the US.
I think that this design will cost you approx. 550 to build. Maybe a bit cheaper or more expensive, it also depends on the horn driver.
I figure three you see that the woofer is filtered with 6 dB/oct, they've done this to minimize phase shifting. You also see that the membrane resonance of the woofer is not damped very much. You can also see that in the decay diagram on the 2nd measurements page. It's a pitty that you can't see how steep they have filtered the mid/woofer. Probably also 6dB/oct else you'll get more troubles with phase shifting.
All speaker designs are compromises.....
The phase shift problem in 2.5 way design for home audio is perhaps compensated in the baffle gain? (By summing the effects of baffle gain upper frequency vs the output dip in the mid crossover.)
Is there a special reason for you not to look for a studio monitor or good PA cab to this application? Is it cost?
I have seen the Genelec bass drivers available as genuine spare parts and they are not super expensive.
In fact I built a pair of (passive) speakers for my living room using studio monitor transducers in home audio cabinets ant it turned out quite well - comparable to "HiFi" speakers costing much more than my project. They work well with my Markbass LM II for a squeaky clean bass tone up to a caertain point.
Is there a special reason for you not to look for a studio monitor or good PA cab to this application? Is it cost?
I have seen the Genelec bass drivers available as genuine spare parts and they are not super expensive.
In fact I built a pair of (passive) speakers for my living room using studio monitor transducers in home audio cabinets ant it turned out quite well - comparable to "HiFi" speakers costing much more than my project. They work well with my Markbass LM II for a squeaky clean bass tone up to a caertain point.
Cost is indeed one issue.
Second.
Studio monitors are not sturdy enough (the big ones with 15" woofers are, but they are to bulky to put on stage).
And I have not yet seen good passive PA loudspeakers. For what I have seen and heard most have a bad designed crossover.
So, I need to design one myself. I have al the measurment equipment needed to check if the design does what I have in mind.
billfitzmaurice
Commercial User
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Theoretically the main benefit to a 2.5 is realized when the crossover uses the 6dB voltage sensitivity increase of dual woofers to compensate for the 6dB sensitivity loss below the baffle step frequency. It also can be used to restrict the bandwidth of a second woofer to minimize the deleterious effects of horizontal placement, but that's better addressed by simply not placing woofers horizontally.
The idea behind a 2.5 is good but it's just plain better to make a three way concept and have your crossover point near the bafflestep peak. But now we're heading towards hifi and studio applications.
Lets stick to the 2x10cab (and cabs in general) stuff
I like talking about all this but maybe we can open a different thread for that.
billfitzmaurice
Commercial User
- Sep 15, 2004
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Duke brought up the 2.5 with respect to the 2x10 cab, pointing out that with horizontally placed drivers they should either be crossed at less than 1.5kHz (IMO less than 1.2kHz would be better) or one of the woofers should be low-passed at that frequency or lower. His point was with respect to the inevitable comb filtering that would occur if they were run higher.Lets stick to the 2x10cab (and cabs in general) stuff
What he didn't mention was the halving of the horizontal dispersion within the bandwidth where the drivers are fully coupled.
I'm all for building superior cabs, but you can't build one if you start with an inferior topology, and placing woofers horizontally does just that.
As I allready said, I appreciate all input from everyone. And it's true (like I allready said) comb filtering effects can occur (they occur way more with a regular 2x10 or 4x10!) Though they seem not very present in the simulation I did.
To cross at 1.2khz or below I would need a 12" tractrixhorn. I have thought of that before, the best would be a big coax driver like the BMS 4590 and put it in a 20" tractrix to get a crossover point at aprox. 700hz. Things will get out of proportion so you have to draw a line somewhere. Like I said, all speakerdesigns are compromises.
Btw. I do not think that my design has an inferior topology, my starting point was to get more of a point source then all the other cabs.
I' going to the drawingboard again and try to implement a 12" tractrixhorn to get the crossover point down a few hundred hz. The cab will only look a bit weird with such a big horn, but what the hell....let's go for it.
Maybe I can push it even below 1.2khz. Then I really need to use a 18dB/oct highpass for the horndriver, else it wil not handle the power
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I'm thinking about this driver Link Removed
Maybe I can push it even below 1.2khz. Then I really need to use a 18dB/oct highpass for the horndriver, else it wil not handle the power
.I'm thinking about this driver Link Removed
