Well I was playing around (for the first time) with the xbaffle open-baffle spreadsheet to see how the Fostex FE206E and the 18" Goldwood GW-1858 driver looks for open baffle use. _Here are my results. _The Goldwood driver looks promising, at least compared to the emminence driver. _The FE206E obviously does not have any low end in an open baffle. I'm not sure how accurate this spreadsheet is to real-world results/sound. _A crossover point of 200hz looks like a good starting point for the Goldwood. _If the FR graph is to be believed, that 104db bump at 45hz of the 1858 compensates nicely for the low end drop off when used in an open baffle.
Room Response: http://www.speechstreet.com/temp/gw1858_ob_room.gif
Frequency response: http://www.speechstreet.com/temp/gw1858_ob_fr.gif
spec's and baffle sizes used for calculations...
_ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _Fostex _ _ _Goldwood _ _ _Eminence
_ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _FE206E _ _ _GW-1858 _ _ _Gamma Pro 15CX
Driver Resonant Frequency (Fs - Hz): _ _ _39.00 _ _ _30.00 _ _ _43.00
Driver Electrical Q (Qes): _ _ _ _ _ _0.18 _ _ _1.07 _ _ _1.00
Driver Mechanical Q (Qms): _ _ _ _ _ _3.73 _ _ _6.65 _ _ _6.55
Driver Equiv Volume (Vas - liter): _ _ _54.53 _ _ _524.00 _ _ _225.00
Thermal Power Limit _ (P - VA): _ _ _ _ _ _90.00 _ _ _220.00 _ _ _200.00
DC Resistance _ _ _ _(Re - Ohm): _ _ _6.69 _ _ _6.20 _ _ _5.80
Pk-to-Pk Excursion (Xmax - mm): _ _ _ _ _ _1.50 _ _ _3.36 _ _ _8.00
Effective Cone Dia. _ (D - mm): _ _ _ _ _ _162.00 _ _ _406.00 _ _ _350.00
Baffle Width (mm) _ _ _ _ _ _ _ _ _ _ _380 _ _ _750 _ _ _750
Hight above floor (mm) _ _ _ _ _ _ _ _ _ _762 _ _ _618 _ _ _618
Dist. rear Wall (mm) _ _ _ _ _ _ _ _ _ _1618 _ _ _1618 _ _ _1618
Dist. side Wall (mm) _ _ _ _ _ _ _ __ _ _1000 _ _ _1000 _ _ _1000
Room Response: http://www.speechstreet.com/temp/gw1858_ob_room.gif
Frequency response: http://www.speechstreet.com/temp/gw1858_ob_fr.gif
spec's and baffle sizes used for calculations...
_ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _Fostex _ _ _Goldwood _ _ _Eminence
_ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _FE206E _ _ _GW-1858 _ _ _Gamma Pro 15CX
Driver Resonant Frequency (Fs - Hz): _ _ _39.00 _ _ _30.00 _ _ _43.00
Driver Electrical Q (Qes): _ _ _ _ _ _0.18 _ _ _1.07 _ _ _1.00
Driver Mechanical Q (Qms): _ _ _ _ _ _3.73 _ _ _6.65 _ _ _6.55
Driver Equiv Volume (Vas - liter): _ _ _54.53 _ _ _524.00 _ _ _225.00
Thermal Power Limit _ (P - VA): _ _ _ _ _ _90.00 _ _ _220.00 _ _ _200.00
DC Resistance _ _ _ _(Re - Ohm): _ _ _6.69 _ _ _6.20 _ _ _5.80
Pk-to-Pk Excursion (Xmax - mm): _ _ _ _ _ _1.50 _ _ _3.36 _ _ _8.00
Effective Cone Dia. _ (D - mm): _ _ _ _ _ _162.00 _ _ _406.00 _ _ _350.00
Baffle Width (mm) _ _ _ _ _ _ _ _ _ _ _380 _ _ _750 _ _ _750
Hight above floor (mm) _ _ _ _ _ _ _ _ _ _762 _ _ _618 _ _ _618
Dist. rear Wall (mm) _ _ _ _ _ _ _ _ _ _1618 _ _ _1618 _ _ _1618
Dist. side Wall (mm) _ _ _ _ _ _ _ __ _ _1000 _ _ _1000 _ _ _1000
You may also want to look at Studio Pro 18" PW1808-US, lower Fs, higher x-max, although it does have a bit lower Qts...
Peace
Peace
What about the dayton 15" ib woofer with 14mm xmax? it will have much more Vd than a tiny xmax 18" of cheaper quality.
If i could fit an IB,or dipole and amps,id try this out due to people here loving the sound of dipoles :-D
dayton 15"
Excuse my sillyness-but WHICH graph do i take note of!
there are 3 the same...
because the FR (onewoofer) looks good,yet the graph on the driver input page,and room response looks bad...
Cheers
If i could fit an IB,or dipole and amps,id try this out due to people here loving the sound of dipoles :-D
dayton 15"
Excuse my sillyness-but WHICH graph do i take note of!
there are 3 the same...
because the FR (onewoofer) looks good,yet the graph on the driver input page,and room response looks bad...
Cheers
I'd be concerned with the low xmax of the goldwood. You might want to calculate how much SPL you can get with the goldwood before you run out of travel. i suspect it wouldn't take much power at all to run out of xmax at 30Hz or so.
This is very similar to what I've been planning -- Fostex FE206E along with an Eminence Kilomax-18. I've got the eminence running with right now with some temporary mids and a tweeter. The Kilomax is moving a fair amount -- way more than 4 mm.
- Robert
This is very similar to what I've been planning -- Fostex FE206E along with an Eminence Kilomax-18. I've got the eminence running with right now with some temporary mids and a tweeter. The Kilomax is moving a fair amount -- way more than 4 mm.
- Robert
I "arrived" at the bump by looking at the response graph that Goldwood sent me. You can see it by clicking on the "104db bump" link I posted above.
I saw that Pyramid Studio Pro driver, and yes it also looks good. I could not find a response graph for it though, or who to send an email to in order to get it (like I did for Goldwood). Anyone know where is the Pyramid home page?
That Dayton driver is too inefficient for my taste.
I'm not so concerned with the xmax as I'm planning on running 2, or maybe 4 drivers total, so things would have to get aweful loud before I start hitting the xmax limit.
The Kilomax driver looks good, but I question if it's worth the extra money, when you can get 4 of the goldwood drivers for less. I'm not convinced that you have to spend allot on drivers for open baffle use. Also, what's it's efficiency, I couldn't find it? And the FR graph doesn't plot the impedance - though the Zmax is quite high.
I may put a couple other drivers through the spreadsheet and see what happens. Or, someone else could do it for the Kilomax, and Pyramid?
I saw that Pyramid Studio Pro driver, and yes it also looks good. I could not find a response graph for it though, or who to send an email to in order to get it (like I did for Goldwood). Anyone know where is the Pyramid home page?
That Dayton driver is too inefficient for my taste.
I'm not so concerned with the xmax as I'm planning on running 2, or maybe 4 drivers total, so things would have to get aweful loud before I start hitting the xmax limit.
The Kilomax driver looks good, but I question if it's worth the extra money, when you can get 4 of the goldwood drivers for less. I'm not convinced that you have to spend allot on drivers for open baffle use. Also, what's it's efficiency, I couldn't find it? And the FR graph doesn't plot the impedance - though the Zmax is quite high.
I may put a couple other drivers through the spreadsheet and see what happens. Or, someone else could do it for the Kilomax, and Pyramid?
Here's the comparison of the Pyramid driver to the Goldwood via the spreadsheet. They performance looks almost identicle (as is their price), in this sim/spreadsheet anyway...
Frequency Response: http://www.speechstreet.net/temp/goldwood-pyramid-fr.gif
In-room (whatever this is really representing?)...
http://www.speechstreet.net/temp/goldwood-pyramid-room.gif
For me the interesting thing is if the Pyramid driver's Le as low as the Goldwood (.6 mH)? And what does the Pyramid impedance plot look like? Zmax?
Data for the sim...
XL-Baffle Version 0.9 - prerelease version
Fostex 8" Goldwood 18" Pyramid 18"
FE206E GW-1858 Studio Pro
Driver Resonant Frequency (Fs - Hz): 39.00 30.00 24.56
Driver Electrical Q (Qes): 0.18 1.27 0.91
Driver Mechanical Q (Qms): 3.73 6.65 8.12
Driver Equiv Volume (Vas - liter): 54.53 524.00 900.00
Thermal Power Limit (P - VA): 90.00 220.00 325.00
DC Resistance (Re - Ohm): 6.69 6.20 7.20
Pk-to-Pk Excursion (Xmax - mm): 1.50 3.36 4.60
Effective Cone Dia. (D - mm): 162.00 438.00 438.00
Baffle Width (mm) 380 750 750
Hight above floor (mm) 762 618 618
Dist. rear Wall (mm) 1618 1618 1618
Dist. side Wall (mm) 1000 1000 1000
Frequency Response: http://www.speechstreet.net/temp/goldwood-pyramid-fr.gif
In-room (whatever this is really representing?)...
http://www.speechstreet.net/temp/goldwood-pyramid-room.gif
For me the interesting thing is if the Pyramid driver's Le as low as the Goldwood (.6 mH)? And what does the Pyramid impedance plot look like? Zmax?
Data for the sim...
XL-Baffle Version 0.9 - prerelease version
Fostex 8" Goldwood 18" Pyramid 18"
FE206E GW-1858 Studio Pro
Driver Resonant Frequency (Fs - Hz): 39.00 30.00 24.56
Driver Electrical Q (Qes): 0.18 1.27 0.91
Driver Mechanical Q (Qms): 3.73 6.65 8.12
Driver Equiv Volume (Vas - liter): 54.53 524.00 900.00
Thermal Power Limit (P - VA): 90.00 220.00 325.00
DC Resistance (Re - Ohm): 6.69 6.20 7.20
Pk-to-Pk Excursion (Xmax - mm): 1.50 3.36 4.60
Effective Cone Dia. (D - mm): 162.00 438.00 438.00
Baffle Width (mm) 380 750 750
Hight above floor (mm) 762 618 618
Dist. rear Wall (mm) 1618 1618 1618
Dist. side Wall (mm) 1000 1000 1000
Here a comparison of Goldwood, Pyramid, and Eminence (Kilomax) 18" drivers...
http://www.speechstreet.com/temp/goldwood-pyramid-eminence-fr.gif
Although the Kilomax can handle tons more power, it doesn't look to be the best choice for open baffle bass response (if this spreadsheet is to be believed). The proof is in the hearing though - and baffle construction.
Again, given these are all "pro" drivers, they are ALL made to handle much more power than I believe they will see for audio use, at least in MY house. Especially since I will be running more than just one - ie, not just a single subwoofer.
I'm really hoping that this bears out, as it would be nice if you can get away with $70 drivers instead of $300 drivers for open baffle use.
http://www.speechstreet.com/temp/goldwood-pyramid-eminence-fr.gif
Although the Kilomax can handle tons more power, it doesn't look to be the best choice for open baffle bass response (if this spreadsheet is to be believed). The proof is in the hearing though - and baffle construction.
Again, given these are all "pro" drivers, they are ALL made to handle much more power than I believe they will see for audio use, at least in MY house. Especially since I will be running more than just one - ie, not just a single subwoofer.
I'm really hoping that this bears out, as it would be nice if you can get away with $70 drivers instead of $300 drivers for open baffle use.
Hi Brad
Have you considered the Goldwood GW215 15" drivers? When you compare them to the GW1858 in XL Baffle, they model flatter in the bass region than the 1858 (due to a higher Q). ITO peak SPL the 18" drivers give only about a 6dB advantage, but at the expense of a rising response. In the low bass there is little to choose between them. Here's the kicker though: the GW215 drivers cost only US$23 each at PartsExpress if you take more than four (which I assume you will be doing), so you can get THREE GW215s for the price of one GW1858. As long as space is not an issue (which it doesn't seem to be as you're contemplating more than one 18" driver per side) I think that the GW215 will be better suited to your needs. Three GW215 drivers are sure to be superior to a single GW1858. If you have the space you can mount six GW215 drivers per side
on a baffle that will be about 8.5 feet tall 
. The cost will be the same as two GW1858 drivers per side, and should sound better (not too mention look a LOT meaner 
).
Enjoy,
Deon
Have you considered the Goldwood GW215 15" drivers? When you compare them to the GW1858 in XL Baffle, they model flatter in the bass region than the 1858 (due to a higher Q). ITO peak SPL the 18" drivers give only about a 6dB advantage, but at the expense of a rising response. In the low bass there is little to choose between them. Here's the kicker though: the GW215 drivers cost only US$23 each at PartsExpress if you take more than four (which I assume you will be doing), so you can get THREE GW215s for the price of one GW1858. As long as space is not an issue (which it doesn't seem to be as you're contemplating more than one 18" driver per side) I think that the GW215 will be better suited to your needs. Three GW215 drivers are sure to be superior to a single GW1858. If you have the space you can mount six GW215 drivers per side
on a baffle that will be about 8.5 feet tall . The cost will be the same as two GW1858 drivers per side, and should sound better (not too mention look a LOT meaner ).Enjoy,
Deon
bbaker6212
I'm a person that appreciates 18 drivers. With that being
said, I think you would be making a mistake going for the Goldwood 1858.
Eminence will stand by their published specs. Will Goldwood
do the same?
I understand you want an open baffle type bass system.
However, Goldwood 1858 has a no. of 0.873%, with a
xmax of 3.36 mm, where as the Eminence Killomax 18
has an no. of 1.433, and, an xmax of 9.8 mm
So, two Goldwood 1858's will be a tad under one Eminence
Killomax 18. This is of course Goldwood's TS Parameters
are correct.
Companies can get away making a cheap 15, 12, 10, and,
8 inch woofer. But, they can't with a 18, 21, or 24 inch
woofer.
I'm a person that appreciates 18 drivers. With that being
said, I think you would be making a mistake going for the Goldwood 1858.
Eminence will stand by their published specs. Will Goldwood
do the same?
I understand you want an open baffle type bass system.
However, Goldwood 1858 has a no. of 0.873%, with a
xmax of 3.36 mm, where as the Eminence Killomax 18
has an no. of 1.433, and, an xmax of 9.8 mm
So, two Goldwood 1858's will be a tad under one Eminence
Killomax 18. This is of course Goldwood's TS Parameters
are correct.
Companies can get away making a cheap 15, 12, 10, and,
8 inch woofer. But, they can't with a 18, 21, or 24 inch
woofer.
I don't understand why so many people here are so focused on xmax. With drivers of this size and efficiency I don't think xmax is really important as I don't think there will be any problem with moving enough air. That said, I think it's better to have low xmax drivers as they are more linear (less distortion) if used within their excursion limits. That's probably contraversial here, but that's my opinion.
Btw, excuse my ignorance but what is "no."
I haven't decided to go with the Goldwood just yet. I'm actually leaning towards the Pyramid at this point - I just wish I could get a hold of it's response and impedance plot.
Deon, that Goldwood 215 driver is too inefficient for me at 87db. I don't want to have to run six of these A 20 oz magnet and foam surrounds? This is stretching things as far as cheapness goes.
Btw, excuse my ignorance but what is "no."
I haven't decided to go with the Goldwood just yet. I'm actually leaning towards the Pyramid at this point - I just wish I could get a hold of it's response and impedance plot.
Deon, that Goldwood 215 driver is too inefficient for me at 87db. I don't want to have to run six of these
A 20 oz magnet and foam surrounds? This is stretching things as far as cheapness goes.
sreten said:
Well in that case the quoted parameters are miles out ?
Or the FR measurement is done in a closed box? It seems as if the resonance frequency is some 45 Hz, or a factor 52/30=1.7 higher than free air. Q in the box would be 2.6 or something, which is 2.6/1.07=2.4 times. (I get these figures by overlaying a simulation on the graph).
Anyway, since both Q and fres are higher than stated in the data sheet, I suspect that the box used is not infinitely large. Since the Vas is 524 litres, the box need not be *that* small to end up with this curve.
This would maybe also explain the baffle step (?) seen above 1kHz.
sreten said:Hi Svante,
but we are talking open baffles here.
Baffle step above 1K doesn't happen for an 18" unit.
(The graph also states 1/2 space, i.e. a large baffle)
The graph also shows Fs at 27Hz.
Something is seriously wrong, modelling or measurement wise.
Yes, I realise that you are talking open baffles, but I suspected that the FR graph (but not the impedance graph) was measured in a large but not infinitely large box. Hmm, I am now realising that the measurement is *not* from the manufacturer as I thought, then I *do* wonder about the measurement conditions (and I don't trust the statement "half space" (yet at least
)). Anyway, I have seen such descrepancies between impedance and FR before on I think seas or vifa drivers. They state that they measure as Peerless (ie in a wall of an anechoic chamber), but it does not add up unless one uses a box for one of the graphs.
You are right that the baffle step cannot occur at 1kHz for a 18" driver, silly me.
bbaker6212 said:
Efficiency has absolutely nothing to do with how much excursion/xmax you need in your drivers. For an 18" driver to produce a given SPL at a given frequncy in identical enclosures, a driver that's 80dB/W/m and one that's 105dB/W/m will both have to have exactly the same excursion, it'll just take a lot more power to get that excursion with the 80dB/W/m driver...
Peace
bbaker6212
I don't understand why so many people here are so focused on xmax. With drivers of this size and efficiency I don't think xmax is really important as I don't think there will be any problem with moving enough air. That said, I think it's better to have low xmax drivers as they are more linear (less distortion) if used within their excursion limits. That's probably contraversial here, but that's my opinion.
OMNIFEX
Well, when you decide to reproduce 80 Hertz down, its the
xmax that gives you the volume. This is why you can have
an 87 dB woofer with 12 mm xmax out shine a 92 dB woofer
with 3 mm xmax.
bbaker6212
Btw, excuse my ignorance but what is "no."
OMNIFEX
no.= The reference efficiency of a driver with a half-space acoustical load. I tend to use this more than the published
1 watt, 1 meter dB measurements on a spec sheet.
Put it like this. The Eminence Killomax 18 is known for
being inefficent in the Pro Audio World. This is
understandable due to the 9.8 mm xmax. The Goldwood
1858 is ruffly 3 dB less than the Killomax and has a 3.36 mm xmax. Most ifnot all 3 - 6 mm xmax 18 inch woofers have a
3 db lead over the Eminence Killomax 18.
Eminence Killomax 18: xmax 9.8 mm, 93.76 dB 1 watt, no. 1.433%
Eminence Omega 18: xmax 5.5 mm, 98 dB 1 watt, no. 2.997%
Goldwood 1858: xmax 3.36 mm, 91.61 dB 1 watt, no. 0.873%
As you can see this 18 has the efficency of a 12
subwoofer, and, the xmax of an 8 inch speaker.
Not to mention, you are using an open baffle, so
these numbers will reflect the amount of volume
you will encounter, considering you will not have
any spl gain from the cabinet.
I don't understand why so many people here are so focused on xmax. With drivers of this size and efficiency I don't think xmax is really important as I don't think there will be any problem with moving enough air. That said, I think it's better to have low xmax drivers as they are more linear (less distortion) if used within their excursion limits. That's probably contraversial here, but that's my opinion.
OMNIFEX
Well, when you decide to reproduce 80 Hertz down, its the
xmax that gives you the volume. This is why you can have
an 87 dB woofer with 12 mm xmax out shine a 92 dB woofer
with 3 mm xmax.
bbaker6212
Btw, excuse my ignorance but what is "no."
OMNIFEX
no.= The reference efficiency of a driver with a half-space acoustical load. I tend to use this more than the published
1 watt, 1 meter dB measurements on a spec sheet.
Put it like this. The Eminence Killomax 18 is known for
being inefficent in the Pro Audio World. This is
understandable due to the 9.8 mm xmax. The Goldwood
1858 is ruffly 3 dB less than the Killomax and has a 3.36 mm xmax. Most ifnot all 3 - 6 mm xmax 18 inch woofers have a
3 db lead over the Eminence Killomax 18.
Eminence Killomax 18: xmax 9.8 mm, 93.76 dB 1 watt, no. 1.433%
Eminence Omega 18: xmax 5.5 mm, 98 dB 1 watt, no. 2.997%
Goldwood 1858: xmax 3.36 mm, 91.61 dB 1 watt, no. 0.873%
As you can see this 18 has the efficency of a 12
subwoofer, and, the xmax of an 8 inch speaker.
Not to mention, you are using an open baffle, so
these numbers will reflect the amount of volume
you will encounter, considering you will not have
any spl gain from the cabinet.
The FR graph did come drom Goldwood.
I still don't understand how you are calculating ".no"
Also, I'm not sure it's accurate to say the Goldwood 1858 has an efficiency of 92db when it has an output of 104db at 45hz - if the FR graph from Goldwood is accurate. Also, stating the "xmax of an 8 inch driver" doesn't make any sense to me. Xmax is excursion right? So what does the diameter of a driver have to do with it's excursion? This statement just makes me believe you have a bias against this driver (maybe because it is cheap?) instead of using accurate and logical analysis.
No, 80hz or not, xmax is not what gives you the volume. Xmax *and* surface area is what gives you the volume. So two 18" drivers with 4mm xmax will suffice for one 18" with twice the xmax. The only reason the lower efficiency, high xmax, driver will "outshine" it is if you feed it more power. This is not my case. I will be running low power, thus I want high efficiency.
I still don't understand how you are calculating ".no"
Also, I'm not sure it's accurate to say the Goldwood 1858 has an efficiency of 92db when it has an output of 104db at 45hz - if the FR graph from Goldwood is accurate. Also, stating the "xmax of an 8 inch driver" doesn't make any sense to me. Xmax is excursion right? So what does the diameter of a driver have to do with it's excursion? This statement just makes me believe you have a bias against this driver (maybe because it is cheap?) instead of using accurate and logical analysis.
No, 80hz or not, xmax is not what gives you the volume. Xmax *and* surface area is what gives you the volume. So two 18" drivers with 4mm xmax will suffice for one 18" with twice the xmax. The only reason the lower efficiency, high xmax, driver will "outshine" it is if you feed it more power. This is not my case. I will be running low power, thus I want high efficiency.
bbaker6212
The FR graph did come drom Goldwood.
OMNIFEX
Does the graph state the measurements are from an open baffle?
bbaker6212
I still don't understand how you are calculating ".no"
OMNIFEX
Actually, Bass Box Pro is doing the math
bbaker6212
Also, I'm not sure it's accurate to say the Goldwood 1858 has an efficiency of 92db when it has an output of 104db at 45hz - if the FR graph from Goldwood is accurate.
OMNIFEX
Well that’s the keyword IF DIY Builders know specs are not always what they seem. I can tell you that with such a high QTS, this woofer is getting its gain from being in a small enclosure. Parts Express list the QTS as 1.04 Now. With a small driver with a QTS of this size, you can build an enclosure and try to gain a flat signal. But, having an 18 inch woofer with QTS of 1.04? You are looking at are
Humongus sealed box.
bbaker6212
Also, stating the "xmax of an 8 inch driver" doesn't make any sense to me. Xmax is excursion right?
OMNIFEX
Yes.
bbaker6212
So what does the diameter of a driver have to do with it's excursion?
OMNIFEX
Large drivers that are designed for sealed enclosures must have a large Xmax to produce bass. If they don’t, they will not produce enough SPL’s at low frequencies, due to running out of xmax.
bbaker6212
This statement just makes me believe you have a bias against this driver (maybe because it is cheap?) instead of using accurate and logical analysis.
OMNIFEX
Bias?
Dude, the analysis I gave (Killomax, vs, Omega, vs, 1858) is as logical, as you can get. Maybe you need to download WinSID Pro
Punch in the numbers, feed all three the same wattage, checkout the excursion, and, SPL graphs, and see what I mean.
If you want to purchase the Goldwood 1858, by all means do so!
However, you did ask for opinions, and, we gave our opinions, in which no one was endorsing this driver. Its not because its cheap. Its because it was designed to work in a sealed cabinet that will increase its gain. This speaker has a large QTS, and, the only way
to increase the SPL’s is to house it in a box smaller than its minimum enclosure requirements. You are using an open baffle. Where are you going to get the gain from?
bbaker6212
No, 80hz or not, xmax is not what gives you the volume. Xmax *and* surface area is what gives you the volume. So two 18" drivers with 4mm xmax will suffice for one 18" with twice the xmax. The only reason the lower efficiency, high xmax, driver will "outshine" it is if you feed it more power. This is not my case. I will be running low power, thus I want high efficiency.
OMNIFEX
Ok. It seems like your mind is already made up, regardless of what anyone says. Just keep in mind High Efficency 18’s have an EBP of 100. The 1858 are in the 20’s. But, I guess that doesn’t matter………
You obviously have some kind of trick to make two Goldwood 1858’s be more efficient than one Eminence Omega 18 in an
open baffle.
Once you finish building your open baffles, you can tell us what you did to accomplish such a fete.
Please keep in mind that I was in no way in my posts
being sarcastic. I just feel that I am not giving you the
answers you are looking for. So, I let someone else share
their thoughts.
Best Regards,
The FR graph did come drom Goldwood.
OMNIFEX
Does the graph state the measurements are from an open baffle?
bbaker6212
I still don't understand how you are calculating ".no"
OMNIFEX
Actually, Bass Box Pro is doing the math
bbaker6212
Also, I'm not sure it's accurate to say the Goldwood 1858 has an efficiency of 92db when it has an output of 104db at 45hz - if the FR graph from Goldwood is accurate.
OMNIFEX
Well that’s the keyword IF DIY Builders know specs are not always what they seem. I can tell you that with such a high QTS, this woofer is getting its gain from being in a small enclosure. Parts Express list the QTS as 1.04 Now. With a small driver with a QTS of this size, you can build an enclosure and try to gain a flat signal. But, having an 18 inch woofer with QTS of 1.04? You are looking at are
Humongus sealed box.
bbaker6212
Also, stating the "xmax of an 8 inch driver" doesn't make any sense to me. Xmax is excursion right?
OMNIFEX
Yes.
bbaker6212
So what does the diameter of a driver have to do with it's excursion?
OMNIFEX
Large drivers that are designed for sealed enclosures must have a large Xmax to produce bass. If they don’t, they will not produce enough SPL’s at low frequencies, due to running out of xmax.
bbaker6212
This statement just makes me believe you have a bias against this driver (maybe because it is cheap?) instead of using accurate and logical analysis.
OMNIFEX
Bias?
Dude, the analysis I gave (Killomax, vs, Omega, vs, 1858) is as logical, as you can get. Maybe you need to download WinSID Pro
Punch in the numbers, feed all three the same wattage, checkout the excursion, and, SPL graphs, and see what I mean.
If you want to purchase the Goldwood 1858, by all means do so!
However, you did ask for opinions, and, we gave our opinions, in which no one was endorsing this driver. Its not because its cheap. Its because it was designed to work in a sealed cabinet that will increase its gain. This speaker has a large QTS, and, the only way
to increase the SPL’s is to house it in a box smaller than its minimum enclosure requirements. You are using an open baffle. Where are you going to get the gain from?
bbaker6212
No, 80hz or not, xmax is not what gives you the volume. Xmax *and* surface area is what gives you the volume. So two 18" drivers with 4mm xmax will suffice for one 18" with twice the xmax. The only reason the lower efficiency, high xmax, driver will "outshine" it is if you feed it more power. This is not my case. I will be running low power, thus I want high efficiency.
OMNIFEX
Ok. It seems like your mind is already made up, regardless of what anyone says. Just keep in mind High Efficency 18’s have an EBP of 100. The 1858 are in the 20’s. But, I guess that doesn’t matter………
You obviously have some kind of trick to make two Goldwood 1858’s be more efficient than one Eminence Omega 18 in an
open baffle.
Once you finish building your open baffles, you can tell us what you did to accomplish such a fete.
Please keep in mind that I was in no way in my posts
being sarcastic. I just feel that I am not giving you the
answers you are looking for. So, I let someone else share
their thoughts.
Best Regards,
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