Rolling Back
A short while back I was planning on building my version of the GR-Research V-2's. I had purchased four of the Eminence Acoustinator N2012 drivers used in that speaker as well as the two SA-1 plate amps from Danny. However, instead of using the coaxial drivers that Danny used in that system, I had a pair of Mark Audio Alpair 10.2's that I was going to use.
Some unforeseen events came up and I had to abandon that project which also meant selling off the items I had bought. The amps sold but no one would bite on the N2012 drivers. I never tried selling the Alpair's.
I'm now in the process of selling off a few more items. Once they sell I'll be able to really get this new project going.
The Plan
So the new plan is to go a little different on the OB design. I've been doing a lot of searching around on the net and getting ideas on how to go about designing these new OB's.
I've already decided on using a pair of Hawthorne Audio 15" Silver Iris speakers for the top end. I want these speakers to cover as much of the audio spectrum as possible on the given baffle size, hence going with the 15's. I've read that these start rolling off around 60Hz or so, so I'll most likely just let them run flat out and roll off on their own.
I've also decided to go ahead and use the N2012 drivers instead of trying to sell them again. They have fairly decent specs for use on an OB, but I'm hoping I can improve on that with the next thing I'm going to talk about, which is...
"Aperture Bass Propagation technology", adopted from Emerald Physics. Basically, this increases the effective width of the baffle, thus increasing the ability of the driver to reach lower before cancellation starts. It is said that it also increases frontal output by up to 4dB starting around 40Hz vs the sound coming from the rear of the driver. Of course, that goes for the Eminence Alpha 15A drivers that Emerald Physics uses in their design. Those numbers will probably be slightly different with the N2012 drivers I'll be using. I don't know if they'll be higher or lower numbers, but should still have the same effect more or less I imagine.
The tricky part of this whole project is that I want to run the entire setup off of one amp, my Monarchy Audio SM-70 Pro. It's Class A and rated at 25w x 2 @ 8 ohms and 40w x 2 @ 4 ohms.
I would like to simply run an inductor across the woofers for a 50-80Hz crossover point. I figure the N2012's will have a combined efficiency of roughly 98dB @ 1w/1m (at 1kHz). Add to that the extra 4dB from the Aperture Bass Propagation technology, so possibly around 102dB efficiency. However, at the frequencies these will be operating at, I'm probably looking closer to around 97-98dB, maybe less.
The Silver Iris 15's are rated at 95.8dB (96dB for all practical purposes), so if the bass section is operating in the 97-98dB area, they should be a pretty good match to the SI 15's at that point, not needing active crossovers and dedicated amps. I don't want to use any extra equalization either, except for the auto-EQ in my HT receiver. If I need more bass below these OB's, I still have a pair of Polk subs that are good down to 25Hz or so.
I'm shooting for a simple, minimalist design and only using the one amp which has loads and loads of woofer control.
Any thoughts, ideas, suggestions?
Many thanks in advance!
A short while back I was planning on building my version of the GR-Research V-2's. I had purchased four of the Eminence Acoustinator N2012 drivers used in that speaker as well as the two SA-1 plate amps from Danny. However, instead of using the coaxial drivers that Danny used in that system, I had a pair of Mark Audio Alpair 10.2's that I was going to use.
Some unforeseen events came up and I had to abandon that project which also meant selling off the items I had bought. The amps sold but no one would bite on the N2012 drivers. I never tried selling the Alpair's.
I'm now in the process of selling off a few more items. Once they sell I'll be able to really get this new project going.
The Plan
So the new plan is to go a little different on the OB design. I've been doing a lot of searching around on the net and getting ideas on how to go about designing these new OB's.
I've already decided on using a pair of Hawthorne Audio 15" Silver Iris speakers for the top end. I want these speakers to cover as much of the audio spectrum as possible on the given baffle size, hence going with the 15's. I've read that these start rolling off around 60Hz or so, so I'll most likely just let them run flat out and roll off on their own.
I've also decided to go ahead and use the N2012 drivers instead of trying to sell them again. They have fairly decent specs for use on an OB, but I'm hoping I can improve on that with the next thing I'm going to talk about, which is...
"Aperture Bass Propagation technology", adopted from Emerald Physics. Basically, this increases the effective width of the baffle, thus increasing the ability of the driver to reach lower before cancellation starts. It is said that it also increases frontal output by up to 4dB starting around 40Hz vs the sound coming from the rear of the driver. Of course, that goes for the Eminence Alpha 15A drivers that Emerald Physics uses in their design. Those numbers will probably be slightly different with the N2012 drivers I'll be using. I don't know if they'll be higher or lower numbers, but should still have the same effect more or less I imagine.
The tricky part of this whole project is that I want to run the entire setup off of one amp, my Monarchy Audio SM-70 Pro. It's Class A and rated at 25w x 2 @ 8 ohms and 40w x 2 @ 4 ohms.
I would like to simply run an inductor across the woofers for a 50-80Hz crossover point. I figure the N2012's will have a combined efficiency of roughly 98dB @ 1w/1m (at 1kHz). Add to that the extra 4dB from the Aperture Bass Propagation technology, so possibly around 102dB efficiency. However, at the frequencies these will be operating at, I'm probably looking closer to around 97-98dB, maybe less.
The Silver Iris 15's are rated at 95.8dB (96dB for all practical purposes), so if the bass section is operating in the 97-98dB area, they should be a pretty good match to the SI 15's at that point, not needing active crossovers and dedicated amps. I don't want to use any extra equalization either, except for the auto-EQ in my HT receiver. If I need more bass below these OB's, I still have a pair of Polk subs that are good down to 25Hz or so.
I'm shooting for a simple, minimalist design and only using the one amp which has loads and loads of woofer control.
Any thoughts, ideas, suggestions?
Many thanks in advance!
I vote for the Manzanita Ultra. 3" FR and 15' GRS woofer. Simple crossover. Great speaker. You can spend a ton more money and get much more complicated for no more results.
http://www.diyaudio.com/forums/multi-way/110583-fast-fun-inexpensive-ob-project-46.html#post2752617
Some as the original Manzanita, but with bigger woofer and baffle.
http://www.diyaudio.com/forums/multi-way/110583-fast-fun-inexpensive-ob-project-46.html#post2752617
Some as the original Manzanita, but with bigger woofer and baffle.
..it's a loudspeaker, right?
And even one that is open baffle!I think that starting with the Silver Iris is sort of a "eh"..or at least that's why I didn't respond when I first read your post.
(..your large format horns + pro drivers were more interesting - at lest conceptually to me.)
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He is suggesting that you can get more for less in an open baffle design..
Same reason I look at the use of the silver iris and go "eh".
Well I'm not building these to impress anyone on the internet, so the "wow factor" to others isn't really a concern of mine. I'm looking at it from a price point/performance perspective. The Hawthorne's or AN's can get me there at a decent price. Another factor for me is overall size of the speakers as I'm working on some limited space.
I've already got $600 invested in bass drivers. In order to get proper compression drivers for the 511B horns (which I still have and already thought about) is gonna be another $500 from GPA. Not to mention, with the horns, I have no choice but to use more amplification, DCX2496, and whatever else needed. Plus, I don't know how well those N2012 drivers would perform up to the crossover point of 600-900Hz to blend into the horns.
Why are the Silver Iris drivers just "ho hum"? It's not like a little cheap 3" wide-range driver is overly exciting.
And keep in mind, I'm planning on these speakers to be fullrange all the way, not needing extra bass support from subwoofers.
I've already got $600 invested in bass drivers. In order to get proper compression drivers for the 511B horns (which I still have and already thought about) is gonna be another $500 from GPA. Not to mention, with the horns, I have no choice but to use more amplification, DCX2496, and whatever else needed. Plus, I don't know how well those N2012 drivers would perform up to the crossover point of 600-900Hz to blend into the horns.
Why are the Silver Iris drivers just "ho hum"? It's not like a little cheap 3" wide-range driver is overly exciting.
And keep in mind, I'm planning on these speakers to be fullrange all the way, not needing extra bass support from subwoofers.
I was just suggesting *a* reason why there hasn't been more interest in the thread. I'm not sure garnering responses is about impressing people (though for some it might be), but rather will they find it interesting enough to respond?
However looking at it from a price-point perspective is EXACTLY what Pano and I are suggesting. In other words we don't think the design you have out-lined is going to net you better performance for the price then something like the little Manzanita. *Different* performance, yes. (..and who knows, performance you might find more meaningful.)
Surprisingly that little 3" driver is excellent (measurably) - probably quite a bit better than the Silver IRS - at least at lower spl's. Still, the Manzanita isn't a design that particularly captures my interest either.
As for what might be more interesting?
Perhaps an open baffle line array, or at least open baffle for the mid-bass drivers - crossing over to your N2012 drivers (also open baffle).
Maybe an MTM open baffle, or an MMTMM (or MMMTM)?
Just some ideas, and the Silver Iris isn't a bad idea it's just not a great one with either objective performance or even subjective performance over a broad group of listeners. (..lots of user's like it, but only a few seem to love it. I'm sure Pano has heard it several times from LSAF alone.)
BTW, this isn't meant to be a "downer" though it reads that way, just something to consider before moving forward.
Note: your proposed bass section does sound interesting to me - and a lot more so than an Alpha-based version.
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Sorry, I thought you were looking for other OB ideas, not analysis or refinement of your ideas. That was not clear to me from your first post (it should have been.) My mistake.
I've offered you ideas and comments in years past and you steadfastly refused to consider them. So I don't think I can offer much help this time, either. Have fun, looks like quite a project!
I've offered you ideas and comments in years past and you steadfastly refused to consider them. So I don't think I can offer much help this time, either. Have fun, looks like quite a project!
I was just suggesting *a* reason why there hasn't been more interest in the thread. I'm not sure garnering responses is about impressing people (though for some it might be), but rather will they find it interesting enough to respond?
However looking at it from a price-point perspective is EXACTLY what Pano and I are suggesting. In other words we don't think the design you have out-lined is going to net you better performance for the price then something like the little Manzanita. *Different* performance, yes. (..and who knows, performance you might find more meaningful.)
Surprisingly that little 3" driver is excellent (measurably) - probably quite a bit better than the Silver IRS - at least at lower spl's. Still, the Manzanita isn't a design that particularly captures my interest either.
As for what might be more interesting?
Perhaps an open baffle line array, or at least open baffle for the mid-bass drivers - crossing over to your N2012 drivers (also open baffle).
Maybe an MTM open baffle, or an MMTMM (or MMMTM)?
Just some ideas, and the Silver Iris isn't a bad idea it's just not a great one with either objective performance or even subjective performance over a broad group of listeners. (..lots of user's like it, but only a few seem to love it. I'm sure Pano has heard it several times from LSAF alone.)
BTW, this isn't meant to be a "downer" though it reads that way, just something to consider before moving forward.
Note: your proposed bass section does sound interesting to me - and a lot more so than an Alpha-based version.
That small Vifa might just be a great little driver, but it's just that, little. It's probably also fairly inefficient. If I am to keep this system completely passive, the considerably more efficient bass drivers will swamp the small drivers. This is also why I haven't put too much thought into using the Alpair 10.2's that I have sitting here.
Likewise, mixing horns with OB bass drivers can also be a bit of a pain for similar reasons, which is why I haven't put too much thought into using them either.
Something I can definitely agree with is the unique bass section I want to attempt. And to improve on it just a little bit more, I was thinking of adding a small, shallow frame on the back of the baffle, maybe 4-6" deep, just for a little added distance from front to rear. Who knows though...
Probably because you veered straight off into a totally different direction, such as in this situation. Sorry, but if it has nothing to do with the matter at hand, I'm not going to pay it much attention.
Seriously, if I'm making plans for a system that's completely fullrange and very efficient, then why suggest something that's not much more than a little bookshelf OB design that's maybe only good down to about 100Hz?!
That makes zero sense to me...
The vifa driver is little and inefficient.. and also relatively in-expensive. i.e. think in MULTIPLES! Yeah, back to the array idea.
BTW, here it is:
http://www.zaphaudio.com/temp/Vifa-TC9FD18-08-FR.gif
http://www.zaphaudio.com/temp/Vifa-TC9FD18-08-HD.gif
http://www.zaphaudio.com/temp/Vifa-TC9FD18-08-CSD.gif
-of course it would also require a line of eff. cheap tweeters as well to reduce combing effects and raise efficiency.
You could also go with a pressure-release cardioid system for the bass drivers (..which are dipole at lower freq.s)
Kimmo has a really nice design for the bass system here:
DIY archive of Kimmo Saunisto
..the KS2125 and the KS-006
Of course his design has lower Qts drivers so you would have more gain in the upper bass/lower mids - which may or may not work well with the low-pass filter. It's the lowpass network/eq. that will be critical - which ever design you end-up with.
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As I went and actually read a little about the Manzanita last night, I noticed that it reaches down into the 40Hz. Sorry, my mistake.
And yes, I know more efficient bass drivers are needed, hence my original suggestion of going with the Silver Iris. It's 96dB, the N2012 in pairs, and on similar baffles to the Emerald CS2.3/2.7 should be somewhere around the 100dB range, if not more.
And yes, I know more efficient bass drivers are needed, hence my original suggestion of going with the Silver Iris. It's 96dB, the N2012 in pairs, and on similar baffles to the Emerald CS2.3/2.7 should be somewhere around the 100dB range, if not more.
Right, the Manzanita is a simple design, but is very full and subjectively has plenty of bass. The "Ultra" version even more so. - bigger woofer, bigger baffle. But neither may be efficient enough for you.
To get efficiency on OB you need a lot of baffle area. Or you have to give up bass. All the Hawthorn designs I've heard gave up bass for efficiency. Their tonal balance is skewed toward the midrange (which some folks like.) Getting 100dB @ 2.83 volts on OB is going to be tough, if you want real bass response. Large baffles and multiple woofer can do it, tho.
I've done the OB 15" woofer and horn design and really liked it, but the crossover is tough to get right.
To get efficiency on OB you need a lot of baffle area. Or you have to give up bass. All the Hawthorn designs I've heard gave up bass for efficiency. Their tonal balance is skewed toward the midrange (which some folks like.) Getting 100dB @ 2.83 volts on OB is going to be tough, if you want real bass response. Large baffles and multiple woofer can do it, tho.
I've done the OB 15" woofer and horn design and really liked it, but the crossover is tough to get right.
Yes a lot of area to have efficiency. 95dB , 0.85 meter width, a monster
Do OB is very difficult...
Do OB is very difficult...
This is another reason for my suggestion of a line array.
*Height* is a component of baffle area (and line arrays as line sources are necessarily tall), even though it doesn't have as much effect on pressure loss as width. It becomes even more important with multiple drivers distributed on the face of the baffle (..in other words the midbass/midrange drivers distributed along the baffle will benefit even more at the bottom of their passband).
So,
-you can sacrifice some baffle width by increasing baffle height.
(say, 18 inches wide by 72 inches high.)
ANOTHER reason arguing for a line array format (with a necessarily tall baffle) is the potential to utilizing combing effects to an advantage - by reducing spl at those "boosted" higher freq.s via extreme driver separation.
More specifically:
-have one 15" bass driver on top of the array and one on the bottom of the array (..with mids and tweets between them).
(i.e. WmmmmmmmmmmmmmmmmW. ..vertically of course)
This can effectively "cut" the rising response (of those woofers) and dramatically improve the integration when only using a 1st order electrical at lower freq.s to both eq. the pressure loss AND act as a low pass filter for integration with the mid-range.
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Hello
I've had the Iris's too and although they are a rather great little unit by themselves...Darrel did a good job...two things made them better for me...swapping out the tweeter to a B&C DE10 and using an active xover via DCX2496 or miniDSP...
I think if you have stuff around...start playing actively...game changer for me...
Just my two cents worth
I've had the Iris's too and although they are a rather great little unit by themselves...Darrel did a good job...two things made them better for me...swapping out the tweeter to a B&C DE10 and using an active xover via DCX2496 or miniDSP...
I think if you have stuff around...start playing actively...game changer for me...
Just my two cents worth
Hmmm..... this is a new and interesting concept to me. Will have to play around with this to see how it works. Chops, didn't you used to have a system like this?
I should note that changing the vertical angle of the drivers helps with canceling-out some of the higher "interverals" (where pressure starts getting closer to the average again).
(..i.e. bottom woofer tilted slightly toward the floor and top woofer tilted slightly toward the ceiling.)
This can be done fairly easily by using a "baffle" on the baffle where the "baffle" connected to the driver (woofer) acts like a "shim" and tilts the driver vertically (when compared to the real baffle - assuming it's 90 degrees (vertical) from the floor).
The added "thickness" of the baffle+baffle for the woofers also helps with aligning acoustic center (..a bit better), by moving the woofers closer to the listener when compared to the mid/tweeter lines.
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