I don't know about tweeters only, but a total listening level of an average 95 dB SPL is likely to happen quite often (a few minutes a day, you know, to check how it sounds loud 
) but usually 85 dB are more than enough for most situations.
Depending on what kind of instruments ar involved in the music program and hot they are miked will influence the CF (Crest Factor=Peaks in the signal) but usually it ranges from 12 to a maximum of 20 dB.
That means that in a system wich has a total 87 dB efficiency (per speaker), transients would range from 35 Watts to more than 350 Watts (per speaker)!!!!
But such transients are not common so I think you will be fine with way less then that, let's say 40 watts or so.
That said, most tweeters will be fine since with most music half the energy is used for frequency below 320 Hz (more or less). So even crossing at 1500 Hz I don't think that more than 15/20 watts could ever go to your tweeters (each). Power compression from the woofers could be an issue if you really want to go over an average of 88-90 dB SPL on (dinamically) uncompressed music.
) but usually 85 dB are more than enough for most situations.Depending on what kind of instruments ar involved in the music program and hot they are miked will influence the CF (Crest Factor=Peaks in the signal) but usually it ranges from 12 to a maximum of 20 dB.
That means that in a system wich has a total 87 dB efficiency (per speaker), transients would range from 35 Watts to more than 350 Watts (per speaker)!!!!
But such transients are not common so I think you will be fine with way less then that, let's say 40 watts or so.
That said, most tweeters will be fine since with most music half the energy is used for frequency below 320 Hz (more or less). So even crossing at 1500 Hz I don't think that more than 15/20 watts could ever go to your tweeters (each). Power compression from the woofers could be an issue if you really want to go over an average of 88-90 dB SPL on (dinamically) uncompressed music.
Adamzuf,
What I think is important in studio monitors is high spl capability. See the rated outputs for well-know monitor manufacturers and compare those to common hifi-speakers (if the data is available, and rarely is, for a reason). Another way to look at the higher output capability is lower distortion for given spl. In a recording environment you need to monitor and mix the recorded material uncompressed. A good, mastered recording might have 20 dB louder sudden transients, so listening at an average of 85 dB comes to 105 dB peak, and this is already compressed (albeit very slightly, at todays standards) music!
So the question is, do you really want to squeeze 40 Hz out of a ~5" driver and hope it'll do the trick? Can you be sure you're not adding compression to tracks just because your monitoring system distorts the transients, if the goal is to make an audiophile recording. I assume you want the system you are going build to be the best possible for the money put in, with no such short comings as drivers driven out of xmax at a dynamic peak. This kind of distortion might be hard to notice and can easily creep into the mixes you make, sending the stereo track already overly compressed (and beyond repair) for mastering.
I hope I made my point clear on the importance of dynamic headroom on the monitor systems in studio applications - Something that just isn't going to happen with small drivers and bandwidth extending to low frequencies. On to the other areas:
I think you are climbing the tree going your *** first. I advice you choose a more mathematically and experimentally treated enclosure than what you are looking at now. The way you are heading is to take expensive drivers and align them in an rather experimental enclosure with needs and good wishes to get around the problems fast. An approach sadly seen to fail or create mediocre outcomes, at best, many times.
On my experience it's best to make the first speakers of good value drivers with with crossovers and enclosure of which behaviour you can predict, especially now that you are in need and might not have the time to do the more on-frontier research. Do the time-consuming and experimental speaker projects as a fun hobby on your spare time with spare cash to throw in.
Your choice on the tweeters is good, both are excellent on the price range, (and even not considering that) imo. I suggest Peerless 830882 for the midbass as it is quite cheap but still manages to better or hold it's own with the more costlier counterparts. With the money you'd save you could buy a subwoofer element for the lower notes.
That is if you're not against using a sub in monitoring. Remember that with Behringer you can easily high- and low-pass the monitors and sub for great integration.
PS. I remember an occasion few years back when I was in a studio which had the small Genelecs, I think 5.25 or maybe even ~4 inch, and the 10-12" 4000 euro per piece far-field monitors with the biggest sub Genelec had the time, and listening to the raw tracks on drum notes especially conveyed the difference rather easily. The bigger speakers sounded a lot more relaxed, as if no great transients were even present, nothing hurt the ears. The smaller monitors outlined the transient attacks (a lot like, I think, most hifi-speakers do) and sounded a lot more upfront even though the few "reference cd's" (commercial and mastered music like Toto, Michael Jackson, Beatles, Pink Floyd, Dido and such) lying around didn't convey such a difference on the different speakers.
I see no short-coming of better speakers, speaking in spl capability, to the distorted ones. Compressed music will sound much the same, but non-compressed will sound a lot more natural through the better system.
What I think is important in studio monitors is high spl capability. See the rated outputs for well-know monitor manufacturers and compare those to common hifi-speakers (if the data is available, and rarely is, for a reason). Another way to look at the higher output capability is lower distortion for given spl. In a recording environment you need to monitor and mix the recorded material uncompressed. A good, mastered recording might have 20 dB louder sudden transients, so listening at an average of 85 dB comes to 105 dB peak, and this is already compressed (albeit very slightly, at todays standards) music!
So the question is, do you really want to squeeze 40 Hz out of a ~5" driver and hope it'll do the trick? Can you be sure you're not adding compression to tracks just because your monitoring system distorts the transients, if the goal is to make an audiophile recording. I assume you want the system you are going build to be the best possible for the money put in, with no such short comings as drivers driven out of xmax at a dynamic peak. This kind of distortion might be hard to notice and can easily creep into the mixes you make, sending the stereo track already overly compressed (and beyond repair) for mastering.
I hope I made my point clear on the importance of dynamic headroom on the monitor systems in studio applications - Something that just isn't going to happen with small drivers and bandwidth extending to low frequencies. On to the other areas:
I think you are climbing the tree going your *** first. I advice you choose a more mathematically and experimentally treated enclosure than what you are looking at now. The way you are heading is to take expensive drivers and align them in an rather experimental enclosure with needs and good wishes to get around the problems fast. An approach sadly seen to fail or create mediocre outcomes, at best, many times.
On my experience it's best to make the first speakers of good value drivers with with crossovers and enclosure of which behaviour you can predict, especially now that you are in need and might not have the time to do the more on-frontier research
. Do the time-consuming and experimental speaker projects as a fun hobby on your spare time with spare cash to throw in.Your choice on the tweeters is good, both are excellent on the price range, (and even not considering that) imo. I suggest Peerless 830882 for the midbass as it is quite cheap but still manages to better or hold it's own with the more costlier counterparts. With the money you'd save you could buy a subwoofer element for the lower notes.
That is if you're not against using a sub in monitoring. Remember that with Behringer you can easily high- and low-pass the monitors and sub for great integration.
PS. I remember an occasion few years back when I was in a studio which had the small Genelecs, I think 5.25 or maybe even ~4 inch, and the 10-12" 4000 euro per piece far-field monitors with the biggest sub Genelec had the time, and listening to the raw tracks on drum notes especially conveyed the difference rather easily. The bigger speakers sounded a lot more relaxed, as if no great transients were even present, nothing hurt the ears. The smaller monitors outlined the transient attacks (a lot like, I think, most hifi-speakers do) and sounded a lot more upfront even though the few "reference cd's" (commercial and mastered music like Toto, Michael Jackson, Beatles, Pink Floyd, Dido and such) lying around didn't convey such a difference on the different speakers.
I see no short-coming of better speakers, speaking in spl capability, to the distorted ones. Compressed music will sound much the same, but non-compressed will sound a lot more natural through the better system.
Except that many pop (and metal and rock and techno) recordings have like no transients (Avril Lavigne i.e.) and a dynamic range of like, 6 dB between parts with acoustic guitar+low voice and full band+high voice, I agree on everything that Samuli^ said.
I just want to add that the power rating of the 5" Revelators is with a 12 dB/oct HP filter @60Hz, not full range.
And extending to 40 Hz flat it's no small thing expecially at high SPL.
You might want to a) add a sub or b) switch from MTM to TWW with a 5" and a 8".
Anyway, just my 2 cents.
I just want to add that the power rating of the 5" Revelators is with a 12 dB/oct HP filter @60Hz, not full range.
And extending to 40 Hz flat it's no small thing expecially at high SPL.
You might want to a) add a sub or b) switch from MTM to TWW with a 5" and a 8".
Anyway, just my 2 cents.
I'm not designing the speaker myself. I have a very respectful speaker designer working on it. I just try to learn as much as possible and come up with ideas, and most things I ask here I ask him as well, but if anything I suggest is not top performance then he would tell me. I just want more views and ideas.
There's not much difference between the 5.5" revelator and the 7", and this is an MTM, if you havn't noticed. They are the same power, same linear Xmax, goes just as low. Perhaps the distortion figures are lesser then the 7" woofers, and a bit lower sensitivity but I'm sure 2 drivers compensates for that to more then adaquate level for nearfiled monitoring.
How would you do it better in a nearfield monitor? Do you recommend the 7" in an MTM? The off axis response won't be as smooth as with the 5.5", that's for sure.
And hey, It's just a sealed box. Not much to it but volume. Add to it that I use an active XO and actually measure the drivers in the box (after my guide measured them as well), And that I will change driver spacing according to XO freq, plus I don't have to refer to impedance and efficiency, I can't see a failure here, and I'm certainly not climbing the tree with my A*s, in fact I'm kind of insulted you said that because you assumed that I'll just do it by intuition and looks or something, but I made clear before that it's certainly not going to be this way, and that I can't do this myself. Maybe I don't know much but I'm making sure that each step I take is a good one.
There's not much difference between the 5.5" revelator and the 7", and this is an MTM, if you havn't noticed. They are the same power, same linear Xmax, goes just as low. Perhaps the distortion figures are lesser then the 7" woofers, and a bit lower sensitivity but I'm sure 2 drivers compensates for that to more then adaquate level for nearfiled monitoring.
How would you do it better in a nearfield monitor? Do you recommend the 7" in an MTM? The off axis response won't be as smooth as with the 5.5", that's for sure.
Are you refering to the sketch I attached or the TL? Anyway, I'm not going for a TL, and on the sketch you can see what is desired to avoid diffractions, I can't see what's wrong with it. You can change it in your mind to just a chamfered box, with wide chamfers. It's not the actual measurements, of coarse they change by all other factors. I bought Loudspeaker Design Cookbook and Speaker Building 201 and I look at those as well and educate myself.
And hey, It's just a sealed box. Not much to it but volume. Add to it that I use an active XO and actually measure the drivers in the box (after my guide measured them as well), And that I will change driver spacing according to XO freq, plus I don't have to refer to impedance and efficiency, I can't see a failure here, and I'm certainly not climbing the tree with my A*s, in fact I'm kind of insulted you said that because you assumed that I'll just do it by intuition and looks or something, but I made clear before that it's certainly not going to be this way, and that I can't do this myself. Maybe I don't know much but I'm making sure that each step I take is a good one.
Phobos said:
I am well aware that the MTM won't go very low. The tweeter has to be in ear's height. a TWW will prevent that, assuming the speaker sits on a console's table. MTM is still good for nearfield, and has much more reasonable setup for active XO. It also leaves 2 free output channel in the DCX2496 for sub.
I will definetly add a sub some day. That is another reason I'm choosing sealed, not only dynamic coherance. but I would like the maximum bass extention from a nearfield, but the accurate bass a vented enclosure can't give me. I've done some thinking, see
Adam
My calculations on power requirements were done taking into accout 2 woofers, in case you didn't check.
You seem very reasonable and my posts didn't imply that you are not able to think, i was just talking like "if I were you..." to share with you my view on the matter.
Anyway, a MTM configuration with two 5" will give you a fast and tight bass with optimum pulse respons but a you have just said, will lack power below 80 Hz for sure.
And do't just look at the predicted bass response form softwares, between all the monitors i used i once tried 2 models of quested that shared the same tweeter but one was a TW with an 8" and the other used two 5.5" from the same series/manufacturer, and i can tell you the even if the anechoic response was nearly the same, the 8" had a far better bass, you could hear it , while with the dual 5.5" it seemed to be attenuated, lighter (before you ask, level was checked with spl meter and speakers were on the same stand in the same room, same position).
This is just to point out that probably, the 7" revelators will actually be different from the 5 inchers, even if what they can give is not what you are looking for.
You seem very reasonable and my posts didn't imply that you are not able to think, i was just talking like "if I were you..." to share with you my view on the matter.
Anyway, a MTM configuration with two 5" will give you a fast and tight bass with optimum pulse respons but a you have just said, will lack power below 80 Hz for sure.
And do't just look at the predicted bass response form softwares, between all the monitors i used i once tried 2 models of quested that shared the same tweeter but one was a TW with an 8" and the other used two 5.5" from the same series/manufacturer, and i can tell you the even if the anechoic response was nearly the same, the 8" had a far better bass, you could hear it , while with the dual 5.5" it seemed to be attenuated, lighter (before you ask, level was checked with spl meter and speakers were on the same stand in the same room, same position).
This is just to point out that probably, the 7" revelators will actually be different from the 5 inchers, even if what they can give is not what you are looking for.
Phobos said:
I was talking to Samuli^ , not you
I know you follow what I say, and I appreciate your help very much, as well as Samuli's good intention, but he doesn't follow my posts as good as you are You meen that impulse response and off axis response I suppose. Yes it is desirable very much.
Another issue I have is that there's no 7" shielded version.
There's an opinion (in the professional community in Israel at least) that 7" ain't suitable for nearfiled monitoring. Is that correct? Why is that?
Most of the flagship nearfileds from companies like Genelec, Mackie, Adam, KRK, Tannoy (they also have a 10" nearfield), Quested use 8" drivers in a TW configuration.
Everything in audio is a compromise, so you can't have it all
It will be extended, dynamic bass or a faster and tighter one. Since woofers don't do much over 2000 Hz: WL=17.4 cm, so less that a 8" diameter, but only the dustcap emits high frequencies in good units, so beaming will hardly be a problem, I think.
Everything in audio is a compromise, so you can't have it all
It will be extended, dynamic bass or a faster and tighter one. Since woofers don't do much over 2000 Hz: WL=17.4 cm, so less that a 8" diameter, but only the dustcap emits high frequencies in good units, so beaming will hardly be a problem, I think.
Hey, let's not get insulted by assuming what the other guy is assuming, okay?
My reason for participating in the conversation is because I'm in the process of designing somewhat similar speakers and for more or less similar usage (as biggest difference my design incorporates a sub from the get go). I want to learn from other peoples projects and share what I know, not to put anyone down.I was talking in a broader, more philosophical sense, and definately not saying that your project is deemed to fail. I am perfectly sure you could make a TL speakers if you put your mind to it, with, or without the help from your friend. The point I was trying to put across was that it generally isn't a good idea trying to do complicated and experimentally-inclined designs when there is urge to finish the project and be done with it. Granted that the advice was misplaced as I now see you have forgotten the TL-design.
I'm was referring to the TL, must have missed the post where you dismissed the TL, oops.
Nothing wrong with the sketch you posted, by the way. Since you are using the speakers in (I assume) acoustically well-treated studio and in near-field, there's not much downside experimenting with mounting the tweeter off-center in order to spread out (in frequency) the baffle diffraction. There is a bunch of free for non-commercial use baffle diffraction simulations (as you probably know already) to give you a rough idea what effect this would have.
Two 5,5" would certainly have somewhat greater output capability than a single 7", given the same excursion. Is it worth the extra cost? That is the million dollar (or 400 euro) question.
7 inchers in MTM would probably be a bad idea, you would have to cross lower than optimal so increased capacity at the low-end would countered by the unnecessary burden placed on the tweeter. I'm expecting great things from the 810921, but I haven't seen anyone measuring it at very loud levels, so until I get the tweeter myself (soon) I can't say anything about how it would react to the abuse.
On the other hand, 7" in MT configuration would have only slightly lower output than two 5,5" and would cost 400e less for a pair. Two 7" in TMM would go louder and/or lower, but would make the design more complicated, and I suspect a sub actively high and low-passed would be better anyways. Bigger revelators start gaining directivity at around 1 kHz, so that can be a problem with this approach.
This obviously goes generally for all drivers: the bigger the driver the sooner it'll start "beaming" the frequencies. Studiomonitor manufacturers usually go about this problem by controlling the tweeters polar response by wave-guides, in order to match it with the woofer at XO. This leads to controlled but downwards sloping power response which might not be a bad idea on studio monitors, as it is somewhat "standard", or at least the "Genelec standard". I think sloping power response would approximate your average speaker better. Having that said I like the more even off-axis response myself. Food for thought, anyways.
As to why 7" would be unsuitable for near-field monitoring, I am at loss. If I would have to guess, it could be the greater path-length between tweeter and mid, but it's not THAT much different.
Continuing with the directivity, I wouldn't put much to the 810921's beaming, as it really starts losing dispersion only at as up as 7 kHz. At those wave-lengths, and in a studio environment, plus near-field you aren't probably going to hear so much of the room anyways. What we miss from the manufacturers data is the 90 degree off-axis, though.
The Revelators sure are expensive. Is it worth it? I don't know. But I do know I want to hit the prime target: fast, tight,reliable bass and midrange. I always liked the sound of smaller drivers, but this design calls for 2 per box. I think I've decided right about ommiting the NeoPro5i and targeting the bass area (into roughly the same budget) as the more important part, also considering that maybe there's too much hype with the ribbons, and after hearing about their relatively high distortion at lower XO points, although the NeoPro5i is meant for public address systems, so it's probably very robust.
Yet it's kind of absurd the box won't reach very low without a sub, on the other hand. But you can't go really full range without 3 drivers unless TL (nearly full range?)
Honest, I can't get the TL idea out of my mind but in here I am afraid of failure, because it will take lots of experimentation.. And PMC didn't make a compact TL MTM (the only TL MTM I've seen is the Thor). But just the thought of that smooth dispertion (vertical and horizontal), two 5" revelators pumping super clean bass, set in a quite small box with TL sound... It makes me drool...
I also talked to a monitor developer that made an MTM with the revelators and he didn't follow d'Appolito's driver spacing formula at all, but just squeezed them as closely as possible, going above the tweeter's front plate. Still have to get the details on how it affected the design, and it's a must that the lobbing problems returns, but to what extent I still have to find out.
Indeed, at my current position, making a TL would be climbing the tree with my a*s, unless someone experienced help me out, or I really get into the math ("very time consuming for a noob" alert) and learn a lot on the subject.
I suppose it is true that If I get the baffle dimentions right (and I believe that it would be hard to screw up, since I'm not th one who's finalizing its size anyway), then I'm free to change the sealed box to a TL.
Maybe the math is not that hard and most of the job is trial and error with parameters that are not worth calculating, like the exact shape of the path, damping material, partition width, stuff that go into the territory of subjective listening.
Darn... Why on earth did you say I might be able to do it, now I'll lose sleep again...
(A poor so called audiophile, that's what I am, bad combination, or maybe a good one?)
Yet it's kind of absurd the box won't reach very low without a sub, on the other hand. But you can't go really full range without 3 drivers unless TL (nearly full range?)
Honest, I can't get the TL idea out of my mind but in here I am afraid of failure, because it will take lots of experimentation.. And PMC didn't make a compact TL MTM (the only TL MTM I've seen is the Thor). But just the thought of that smooth dispertion (vertical and horizontal), two 5" revelators pumping super clean bass, set in a quite small box with TL sound... It makes me drool...
I also talked to a monitor developer that made an MTM with the revelators and he didn't follow d'Appolito's driver spacing formula at all, but just squeezed them as closely as possible, going above the tweeter's front plate. Still have to get the details on how it affected the design, and it's a must that the lobbing problems returns, but to what extent I still have to find out.
Indeed, at my current position, making a TL would be climbing the tree with my a*s, unless someone experienced help me out, or I really get into the math ("very time consuming for a noob" alert) and learn a lot on the subject.
I suppose it is true that If I get the baffle dimentions right (and I believe that it would be hard to screw up, since I'm not th one who's finalizing its size anyway), then I'm free to change the sealed box to a TL.
Maybe the math is not that hard and most of the job is trial and error with parameters that are not worth calculating, like the exact shape of the path, damping material, partition width, stuff that go into the territory of subjective listening.
Darn... Why on earth did you say I might be able to do it, now I'll lose sleep again...
(A poor so called audiophile, that's what I am, bad combination, or maybe a good one?)Excuse me for the maybe stupid question, but from my easy going on my books, I still don't know the importance of baffle width except the frequency in which radition goes from half space to free space.
Maybe I'm in the wrong direction, but I suppose it makes sense to have the baffle step only in the area of the woofers, concluding that it makes sense to cause it to begin below the XO point, in a frequency in which the tweeter's level becomes negligible (how much -dB is that, by the way?), in order to simplify the crossover.
Now if someone can add the guidlines of the chamfers into that I would really be glad...
Maybe I'm in the wrong direction, but I suppose it makes sense to have the baffle step only in the area of the woofers, concluding that it makes sense to cause it to begin below the XO point, in a frequency in which the tweeter's level becomes negligible (how much -dB is that, by the way?), in order to simplify the crossover.
Now if someone can add the guidlines of the chamfers into that I would really be glad...
For practical reasons (dimensions), Baffle Step happens usually over 200 Hz. If i may add something, (but your friend will be thinkin of that already for sure) use very thick wood for the front and get the edges rounded by an expert woodcraftsmen. Or you could even get a Thick baffle that goes from square in the back side to a hourglass shape in the front. Sorry for my english, but i dont know how to explain it better it's not really a big deal for a woodcraftsman (well, for a good one).
I'm adding a photo taken from the Avalon site.
Now i'm talking about a baffle like this but with rounded edges to further reduce diffraction errors and get a better imaging.
Another relatively cheap trick is insulating the cabinet from the desk with spikes: the ones that come with a little "coin" to put the spike on are good too, but not the ones with the spike/cone attached to the little disk; the latter behave just like cilinders, since what count is the contact surface.
Another way of insulation could be a foam base like this one.
And even if i'm sure the Revelators are a good choice, the Avalon flagship monitor uses a 8" Accuton ceramic driver.
Take a look at their 5" measurements: C89T6. The yalso make a 13 ohm version that could be nice to use if you want to wire the two woofers in parallel.
Here's their website: http://www.accuton.com/e_index_netscape1280.html
I'm adding a photo taken from the Avalon site.
An externally hosted image should be here but it was not working when we last tested it.
Now i'm talking about a baffle like this but with rounded edges to further reduce diffraction errors and get a better imaging.
Another relatively cheap trick is insulating the cabinet from the desk with spikes: the ones that come with a little "coin" to put the spike on are good too, but not the ones with the spike/cone attached to the little disk; the latter behave just like cilinders, since what count is the contact surface.
Another way of insulation could be a foam base like this one.
And even if i'm sure the Revelators are a good choice, the Avalon flagship monitor uses a 8" Accuton ceramic driver.
Take a look at their 5" measurements: C89T6. The yalso make a 13 ohm version that could be nice to use if you want to wire the two woofers in parallel.
Here's their website: http://www.accuton.com/e_index_netscape1280.html
That's the biggest downfall on designing a TL, imo. It just goes way too much to the grey area where you can't anymore be sure how the chances you make will affect the design. On top of that is the laborous problems of empirically tuning the cabinet. First problem is simply, how to do it? Adding and taking out stuffing is easy enough, but if you want to change dimensions of the quarter-wave resonator, it's going to be time consuming series of trial, error and re-doing the cabinet. Second problem is, how to measure the changes? You'd have to get the speaker out on the yard every time you make a change to get accurate measurements on the low-end. Tuning by ear only is an approach doomed to fail, imo.
Let's assume an impulse is produced by the loudspeaker-element, and it then travels along the front-panel until seeing the edge and new acoustic space, spreading out. This leads to pressure drop of the impulse which then, as collapsing sends a sound wave of opposite polarity and 6 dB lower in magnitude propagating from the edge towards the listener.
Best way visualize this might be by imagining two (or more tweeters in effect at every point of the cabinets edge), that are delayed in time by the amount it takes for the wave to emanate from the tweeter to the cabinet edge and that are 180 degree out of phase. At low frequencies the delay is insignificant in respect to wave-lengths and hence phase, so the emanating, out of phase, signal is destructively interfering with the sound from the tweeter.
I hold this pet theory that subjective impressions of small speakers having better imaging might be accounted for the lesser delay of the diffraction at edges but I have nothing to back this up, and the opposite might in fact be true. Maybe there's nothing more to a small speakers usually having better imaging than the off-axis response?
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