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First DIY project for a guy looking to upgrade - multiple sealed 18s? - Page 3

post #61 of 1005
Quote:
Originally Posted by Erich H View Post

What would be the best enclosure size for single RS18's and a 1000 watt amp?

About 2-2.5cuft for a single driver.
post #62 of 1005
Eric give me a couple of weeks with it and I will let you know something more solidly informed than just the models. I have a couple of amps in the 1000-1500w at 4 ohms range which are probably more robust than a 1000 w plate and I have 3 different size sealed 18" boxes. The small one is under 3 cubes.
post #63 of 1005
The ho18 driver looks really good and seems to be well built. Xmech is about 30mm in when the coil lands near as I can tell. Perhaps a bit more. It doesnt take a whole lot of power to tap the backplate in free air. It is nice and quiet in operation. Its good through the first 30-35mm excursion. Somewhere around 45mm peak to peak maybe 50mm even the coil starts to offset the center of the stroke outward what looks like maybe 7 or 8 mm. Perhaps because the bottom of the coil is starting to leave the gap. Like the magnetic center suddenly changes when driven that hard. I will see if I can get a video of this behavior. Anyway that is a oittle past the envelope it is designed for anyway.
post #64 of 1005
Very good. Look forward to more thorough testing.
post #65 of 1005
Thread Starter 
Quote:
Originally Posted by Ricci View Post

The ho18 driver looks really good and seems to be well built. Xmech is about 30mm in when the coil lands near as I can tell. Perhaps a bit more. It doesnt take a whole lot of power to tap the backplate in free air. It is nice and quiet in operation. Its good through the first 30-35mm excursion. Somewhere around 45mm peak to peak maybe 50mm even the coil starts to offset the center of the stroke outward what looks like maybe 7 or 8 mm. Perhaps because the bottom of the coil is starting to leave the gap. Like the magnetic center suddenly changes when driven that hard. I will see if I can get a video of this behavior. Anyway that is a oittle past the envelope it is designed for anyway.

Great feedback Josh, thank you. So I assume it's safe to say the quoted 12.75mm Xmax number is a tid bit conservative? tongue.gif

Quote:
Originally Posted by Scott Simonian View Post

Very good. Look forward to more thorough testing.

X2!!!
Edited by Gorilla83 - 10/31/12 at 5:32am
post #66 of 1005
Thread Starter 
Josh - have you played with the Dayton 15" Titanic driver at all? I was playing around with modeling these subs, each in a 3cu foot box with max rated power and the difference between this driver and the HO 18" is not all that significant. Of course I did use the 13mm xmax figure for the 18 when modeling. Now, if the 18" xmax can move to 20mm or so, then more power and/or a bigger box can be applied which tips the tables quite a bit.

dayton ho 18 vs dayton titanic 15.JPG 103k .JPG file
post #67 of 1005
Thread Starter 
Another interesting comparison:

4 X Dayton Reference 18's and 3600 watts in a 9 cu ft enclosure (yellow). $1000 of drivers shipped.

Vs.

2 X LMS Ultra 5400s in a 8 cu ft enclosure and 4000 watts (orange) $1900 of drivers, shipped.

Both within rated Xmax to 10hz, both go over by a few mm under 10hz. LMS pair has a couple db below 20hz, then Daytons take over >20hz.

4xdayton18vs2xlms5400sealed.jpg


2 X Daytons in 5 cu feet with 2500 watts vs 2 X LMS5400 and 4000 watts in 7 cu feet

Clear advantage to LMS sub 30hz, but very close 40hz and up! $500 vs. 1900. biggrin.gif

2xdayton18vs2xlms5400.jpg
Edited by Gorilla83 - 10/31/12 at 7:28am
post #68 of 1005
I've never played with the 15" but many many have and it's been klippel tested. No need to go there. Assuming the same excursion the 18 should give about 3dB more. It may have a little more xmech though.

As far as the xmax ratings here is the thing. There are a lot of drivers that claim 30mm xmax and produce enough mechanical racket at only 20mm to make you fear to drive them any further let alone consider it useful output to use. Then there are drivers that claim 9mm xmax that can be useful out at 15mm and won't be damaged by 20. With overhung motors which are the most common type there is rarely a definite and abrupt change in the sound a little past xmax.

With the RS18 it has a 13mm xmax rating which is probably the geometric mathematical rating, but the motor will drive the coil all of the way into the back plate which is about 30mm in as near as I can tell. It makes a lot less noise than many other drivers with longer excursion ratings on paper. It definitely does not suddenly fall all over itself at 13mm and still is doing just fine at about 20mm. That said it can be bottomed pretty hard so you don't want to go too much past there and will need to watch the power. I would suggest modeling to around 20mm excursion as the maximum input power. When I get a chance I will see what types of voltages it will take reliably in a couple of different sized sealed enclosures.
post #69 of 1005
Thread Starter 
Quote:
Originally Posted by Ricci View Post

I've never played with the 15" but many many have and it's been klippel tested. No need to go there. Assuming the same excursion the 18 should give about 3dB more. It may have a little more xmech though.
As far as the xmax ratings here is the thing. There are a lot of drivers that claim 30mm xmax and produce enough mechanical racket at only 20mm to make you fear to drive them any further let alone consider it useful output to use. Then there are drivers that claim 9mm xmax that can be useful out at 15mm and won't be damaged by 20. With overhung motors which are the most common type there is rarely a definite and abrupt change in the sound a little past xmax.
With the RS18 it has a 13mm xmax rating which is probably the geometric mathematical rating, but the motor will drive the coil all of the way into the back plate which is about 30mm in as near as I can tell. It makes a lot less noise than many other drivers with longer excursion ratings on paper. It definitely does not suddenly fall all over itself at 13mm and still is doing just fine at about 20mm. That said it can be bottomed pretty hard so you don't want to go too much past there and will need to watch the power. I would suggest modeling to around 20mm excursion as the maximum input power. When I get a chance I will see what types of voltages it will take reliably in a couple of different sized sealed enclosures.

Thanks Josh! Looking forward to your results. The 5cubic foot model for the pair has them hitting ~19-20mm at 5hz with 2500watts for the pair. I think I should be OK with that design without using a HPF.
post #70 of 1005
Quote:
Originally Posted by Ricci View Post

I've never played with the 15" but many many have and it's been klippel tested. No need to go there. Assuming the same excursion the 18 should give about 3dB more. It may have a little more xmech though.

As far as the xmax ratings here is the thing. There are a lot of drivers that claim 30mm xmax and produce enough mechanical racket at only 20mm to make you fear to drive them any further let alone consider it useful output to use. Then there are drivers that claim 9mm xmax that can be useful out at 15mm and won't be damaged by 20. With overhung motors which are the most common type there is rarely a definite and abrupt change in the sound a little past xmax.

With the RS18 it has a 13mm xmax rating which is probably the geometric mathematical rating, but the motor will drive the coil all of the way into the back plate which is about 30mm in as near as I can tell. It makes a lot less noise than many other drivers with longer excursion ratings on paper. It definitely does not suddenly fall all over itself at 13mm and still is doing just fine at about 20mm. That said it can be bottomed pretty hard so you don't want to go too much past there and will need to watch the power. I would suggest modeling to around 20mm excursion as the maximum input power. When I get a chance I will see what types of voltages it will take reliably in a couple of different sized sealed enclosures.

Thats impressive.

 

I would wager this driver won't stay priced at $250 for long.

post #71 of 1005
These are the numbers or close to it that Craig has always said the 18.2 will do.
post #72 of 1005
Quote:
Originally Posted by Ricci View Post

I've never played with the 15" but many many have and it's been klippel tested. No need to go there. Assuming the same excursion the 18 should give about 3dB more. It may have a little more xmech though.

As far as the xmax ratings here is the thing. There are a lot of drivers that claim 30mm xmax and produce enough mechanical racket at only 20mm to make you fear to drive them any further let alone consider it useful output to use. Then there are drivers that claim 9mm xmax that can be useful out at 15mm and won't be damaged by 20. With overhung motors which are the most common type there is rarely a definite and abrupt change in the sound a little past xmax.

Blasphemy! tongue.gif

Don't you know that 15 is always better than 13?!? rolleyes.gif

From what I've seen, the specified Xmax of the other RS series are straight overhang figures. Sometimes this simple calculation is very conservative (especially as the top plate gets taller), other times it can be optimistic where you have a short gap and very long coil.

In the end someone has to plug it in, observe and abuse a subwoofer driver a little to confirm how those numbers might be best put to use. While not an exact calculation, you can also gain some understanding of what is happening with a given design as you drive near and past Xmax if you compare the response curve with the BL dropping (80-50% gives good insight) and when the suspension stiffens. Since this change isn't there for the first 1/2-3/4 of the travel the response is not exact, but the general change in shape with dynamics is correct.
post #73 of 1005
Quote:
Originally Posted by Gorilla83 View Post

The 5cubic foot model for the pair has them hitting ~19-20mm at 5hz with 2500watts for the pair. I think I should be OK with that design without using a HPF.

IMHO you should look for danger in excursion levels between 10-25Hz and not worry as much down at 3-6Hz. Once you combine the receiver electrical roll off with that of the amplifier and any other electronics in the chain you are very likely to have a signal be 3 to 6dB down at 5Hz compared to 20hz and then there is the fact that the sounds down below 10Hz are almost never as strong as the sounds above. A 6db reduction in signal results in half of the excursion from the driver. Try applying an 8Hz 1st order high pass filter to your models (to approximate the electronics roll off) and look at where the maximum excursion ends up in most instances.
post #74 of 1005
^^^^^^

This.
post #75 of 1005
Thread Starter 
Quote:
Originally Posted by Ricci View Post

IMHO you should look for danger in excursion levels between 10-25Hz and not worry as much down at 3-6Hz. Once you combine the receiver electrical roll off with that of the amplifier and any other electronics in the chain you are very likely to have a signal be 3 to 6dB down at 5Hz compared to 20hz and then there is the fact that the sounds down below 10Hz are almost never as strong as the sounds above. A 6db reduction in signal results in half of the excursion from the driver. Try applying an 8Hz 1st order high pass filter to your models (to approximate the electronics roll off) and look at where the maximum excursion ends up in most instances.

Very helpful, thank you again. So in comparing a 5cu foot box vs. 7cu ft, here's what I'm seeing with a 8HZ 1st order HPF applied:

SPL differences, both being driven by 2500 watts/pair:
2xdayton185cuvs7cusealed.jpg

Excursion:
2xdayton185cuvs7cuexcursion.jpg

The 5cu foot box seems quite a bit more conservative, but gives up a couple DB on the low end. Please do let me know if I'm overlooking anything.
post #76 of 1005
You're not. You got it. wink.gif
post #77 of 1005
Now that I looked at the graph better are we saying this driver can do 93 dBs at 10hz? It is better than a UXL-18 at 10hz? I find that hard to believe. Tell me something different or everyone should be buying this driver right now!
post #78 of 1005
Quote:
Originally Posted by Ricci View Post

IMHO you should look for danger in excursion levels between 10-25Hz and not worry as much down at 3-6Hz. Once you combine the receiver electrical roll off with that of the amplifier and any other electronics in the chain you are very likely to have a signal be 3 to 6dB down at 5Hz compared to 20hz and then there is the fact that the sounds down below 10Hz are almost never as strong as the sounds above. A 6db reduction in signal results in half of the excursion from the driver. Try applying an 8Hz 1st order high pass filter to your models (to approximate the electronics roll off) and look at where the maximum excursion ends up in most instances.
FWIW, I'd recommend measuring rather than making guesses. Some electronics roll off noticeably by 5Hz, some don't. As an example, I found that my Audio-gd NFB-15.1 USB DAC + QSC PLX2402 had a -3dB point of about 2.4Hz when driving an 8 ohm woofer (based on measuring the output voltage of the amp with a scope). That's not exactly a gear setup you'd use to drive a sub, but a -3dB point of 2.4Hz isn't likely to be much protection either.
post #79 of 1005
Quote:
Originally Posted by MKtheater View Post

Now that I looked at the graph better are we saying this driver can do 93 dBs at 10hz? It is better than a UXL-18 at 10hz? I find that hard to believe. Tell me something different or everyone should be buying this driver right now!

Yes and no. Sure, people who want this driver should get it. So far it seems really decent.

But no, the UXL-18 can do a lot more down to 10hz than the Dayton can. If you're using Josh's test's as a comparison, wait til he has tested the Dayton 18HO. wink.gif Also, his tests are done at 2m so that makes the numbers lower than what we see in Unibox/WinISD.
post #80 of 1005

Two 18HOs cost less than one UXL.  Hows that comparo?smile.gif

post #81 of 1005
Quote:
Originally Posted by Scott Simonian View Post

Yes and no. Sure, people who want this driver should get it. So far it seems really decent.
But no, the UXL-18 can do a lot more down to 10hz than the Dayton can. If you're using Josh's test's as a comparison, wait til he has tested the Dayton 18HO. wink.gif Also, his tests are done at 2m so that makes the numbers lower than what we see in Unibox/WinISD.

That is it, I forgot the 2 meter thing. So in winisd it says 93 dBs for one dayton so Josh should get around 87 dBs or so. So two of these should get 93 dBs at 10hz where the UXL-18 gets 92+ dBs. It should be intersting to see the results. Craig said his 18.2 gets 93 dBs as well based on winisd.
post #82 of 1005
Quote:
Originally Posted by Stereodude View Post

FWIW, I'd recommend measuring rather than making guesses. Some electronics roll off noticeably by 5Hz, some don't. As an example, I found that my Audio-gd NFB-15.1 USB DAC + QSC PLX2402 had a -3dB point of about 2.4Hz when driving an 8 ohm woofer (based on measuring the output voltage of the amp with a scope). That's not exactly a gear setup you'd use to drive a sub, but a -3dB point of 2.4Hz isn't likely to be much protection either.

There are always exceptions. Sure you should measure, how many will or do? That still doesn't address the point that it is very unlikely there will be <10Hz signals that are equal strength to the loudest 10-30Hz signals your sub will see. There is also the question of whether most amps can produce their rated power at such deep frequencies. It's my opinion that fretting about an extra 3mm of over excursion at 3 or 5Hz or whatever is misguided.

How many guys reading this have ever damaged a sub driver mechanically? If so do you know what caused it? I've had more than my fair share. None of them were caused by single digit signals. Not one. I'm interested if anyone else has a different experience? Amps on the other hand...
post #83 of 1005
Quote:
Originally Posted by Gorilla83 View Post

The 5cu foot box seems quite a bit more conservative, but gives up a couple DB on the low end. Please do let me know if I'm overlooking anything.

Since you are looking to understand/compare the differences of the 2 box sizes, you could also post an impedance curve of each sub which shows Fb clearly.

IMO, 7 cu.ft. is plenty small and appropriate for 2500W maximum power into a pair of 18s. You are probably pretty safe assuming your crown won't deliver much more equivalent Voltage than this into the drivers when driven hard, which should leave you well limited by the amp clipping, especially with wider spectrum program material vs. test sine waves down low.
post #84 of 1005
Quote:
Originally Posted by Ricci View Post

There are always exceptions. Sure you should measure, how many will or do? That still doesn't address the point that it is very unlikely there will be <10Hz signals that are equal strength to the loudest 10-30Hz signals your sub will see. There is also the question of whether most amps can produce their rated power at such deep frequencies. It's my opinion that fretting about an extra 3mm of over excursion at 3 or 5Hz or whatever is misguided.

How many guys reading this have ever damaged a sub driver mechanically? If so do you know what caused it? I've had more than my fair share. None of them were caused by single digit signals. Not one. I'm interested if anyone else has a different experience? Amps on the other hand...

I agree for most any expected case. For anyone using a receiver or external EQ device, there's not much concern below 10Hz, unless the excursion plot is pitched toward the sky around 10Hz. The only case I've had drivers killed with <10Hz content was when someone combined a fetish with full analog gear and fed the system with DJs spinning turntables. There are some cases you be a little more mindful with very large vented boxes, with large ports tuned into the low teens with soft suspensions (or funky bandpass loading) and lots of power on tap above tuning.

In other words, it's a special and rare case where you need to be concerned and if you have something that ambitious and out of the ordinary you should be testing, measuring carefully and observing as you first start pushing the levels anyway.
post #85 of 1005
Thread Starter 
Quote:
Originally Posted by Mark Seaton View Post

Since you are looking to understand/compare the differences of the 2 box sizes, you could also post an impedance curve of each sub which shows Fb clearly.
IMO, 7 cu.ft. is plenty small and appropriate for 2500W maximum power into a pair of 18s. You are probably pretty safe assuming your crown won't deliver much more equivalent Voltage than this into the drivers when driven hard, which should leave you well limited by the amp clipping, especially with wider spectrum program material vs. test sine waves down low.

Mark - Here is the impedance curve for 5cubes vs. 7. I'm not super clear on how to interpret this other than face value so feel free to teach a man to fish. tongue.gif

2xdayton185cuvs7cuimpediance.jpg
post #86 of 1005
Fb is the frequency where the impedance peak is. You can pretty clearly see the 7cu-ft box is tuned about 6Hz lower than the 5cu-ft box.
post #87 of 1005
Thread Starter 
Quote:
Originally Posted by Stereodude View Post

Fb is the frequency where the impedance peak is. You can pretty clearly see the 7cu-ft box is tuned about 6Hz lower than the 5cu-ft box.

Thank you sir. This is interesting because in the SPL chart they both start to roll off around 50hz.
post #88 of 1005
Ok all of this questioning about what the RS18 is capable of and its xmax rating led me to doing some investigation tonight. Turns out it will take 36v at any freq in free air without hitting the stops. The min impedance is right around 4 ohms so that is 324 watts. When placed in my 4.2 cube sealed enclosure it will accept 75 volts at least without running out of stroke. Thats around 1400w into 4ohms. In a small sealed enclosure you could use 1000-1500w into 4 ohm rated amp channel without worrying about clanking the driver. This drivers excursion is useful to atleast 20mm and has less mechanical noise than many.
post #89 of 1005
Quote:
Originally Posted by Ricci View Post

Ok all of this questioning about what the RS18 is capable of and its xmax rating led me to doing some investigation tonight. Turns out it will take 36v at any freq in free air without hitting the stops. The min impedance is right around 4 ohms so that is 324 watts. When placed in my 4.2 cube sealed enclosure it will accept 75 volts at least without running out of stroke. Thats around 1400w into 4ohms. In a small sealed enclosure you could use 1000-1500w into 4 ohm rated amp channel without worrying about clanking the driver. This drivers excursion is useful to atleast 20mm and has less mechanical noise than many.

damn ricci...awesome work! from a hundred lurkers who will never post...THANK YOU!

parts express better stock up fast because this is going to result in a total blowout... :-)
post #90 of 1005
Don't forget that there is an HF in the works. wink.gif

Still.... awesome stuff wrt the HO18. biggrin.gif
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