Daddy Dee Posted February 20, 2008 Share Posted February 20, 2008 OK. I think we have settled on this woofer for our project. It has the lowest frequency, to 40hz compared to other Eminence Beta 10 or 12 in woofers. We're planning to use the K-65 mid/hf in a two way configuration. The recommended (vented) enclosure volume is 1.3 to 2.2 cu.ft. Is the best choice the top end of this range? Not sure how to determine the appropriate port or vent. Any help appreciated. Eminence Beta-10CX Co-Axial 250W RMS / 500W Peak 40Hz-4kHz . BETA 10CX For all high power bass applications including bass guitar. Nominal Basket Diameter Impedance Power Rating Resonance Usable Frequency Range (with APT-50 and pxb2:3k5) Sensitivity Magnet Weight Gap Height Voice Coil Diameter Mounting Information Recommended Enclosure Volume (vented) Overall Diameter Baffle Hole Diameter Front Sealing Gasket Rear Sealing Gasket Mounting Holes Diameter Mounting Holes B.C.D. Depth Shipping Weight Thiele-Small ParametersResonant Frequency (fs) Impedance (Re) Coil Inductance (Le) Electromagnetic Q (Qes) Mechanical Q (Qms) Total Q (Qts) Compliance Equivalent Volume (Vas) Peak Diaphragm Displacement Volume (Vd) Mechanical Compliance of Suspension (Cms) BL Product (BL) Diaphragm Mass inc. Airload (Mms) Equiv. Resistance of Mechanical Suspension Loss (Rms) Efficiency Bandwidth Product (EBP) Voice Coil Overhang (Xmax) Surface Area of Cone (Sd) Impedance at Resonance (Zmax) Maximum Mechanical Limit (Xmech) 10", 254mm8 ohm 250Wrms / 500Wpeak 38Hz 35Hz - 20kHz 95 dB 38oz. 0.312", 7.94mm 2", 50.8mm 37 - 62 liters 1.3 - 2.2 cu. ft. 10.08", 256.1mm 9.05", 229.7mmfitted as standard fitted as standard0.25", 6.4mm 9.66", 245.4mm 3.98", 101.1mm 8.4lbs., 3.8 kg. 38Hz 5.64 ohm0.99mH 0.29 10.34 0.29 131 liters 4.63 cu. ft. 104cc 0.78mm/N 10.1 T-M 22 grams 0.51N*sec/M 131 3.0mm 344.9cm2204 ohm15.24mm Quote Link to comment Share on other sites More sharing options...
pzannucci Posted February 20, 2008 Share Posted February 20, 2008 There are a bunch of box calculators on the net along with shareware programs. Boxplt is one and others are around on sites such as Madisound. These programs will give you theoretical response plots so depending on how tight you like your bass, you could model accordingly. I believe modifying the Q will change the tightness and amount off boom from the box. Basically underdamped or overdamped bass. You will have to build the box to find out really how it performs based on the room and the proximity to the walls Quote Link to comment Share on other sites More sharing options...
Daddy Dee Posted February 20, 2008 Author Share Posted February 20, 2008 thanks Peter. edit: wow, google is fast. I just went out to google "boxplt" and found your post above on google. Here's what's on google: How to calculate optimal port/vent in a diy project? - The Klipsch ... Boxplt is one and others are around on sites such as Madisound. These programs will give you theoretical response plots so depending on how tight you like ...forums.klipsch.com/forums/p/101222/1020918.aspx - 3 hours ago - Similar pages Quote Link to comment Share on other sites More sharing options...
DrWho Posted February 21, 2008 Share Posted February 21, 2008 Is there any reason in particular you chose this driver? I'm just noticing that it has an Xmax of only 3mm...which is not very condusive to playing low. I went ahead and modelled a 2.2 cu ft enclosure and you're looking at an F3 of 55Hz if you want 110dB at one meter...distortion probably ain't gonna be too impressive either. You'll want to download this program if you want to do some modelling yourself:http://www.linearteam.dk/default.aspx?pageid=winisdpro The help menu is really good and should be able to walk you through the whole modelling process. Of if you want to be lazy, just head over to Eminence where they provide suggested cabinets / alignments:http://www.eminence.com/proaudio_speaker_detail.asp?web_detail_link=BETA-10CX&speaker_size=10&SUB_CAT_ID=2 (The specs on this page differ from the website you linked to - updated driver perhaps?) Just keep in mind that there is way more to the sound of the speaker than just the frequency response...in fact, frequency response 'almost' doesn't matter in a sound reinforcement applciation. Distortion is a big deal though, but you can't use the T/S models to accurately predict it. You will want to be operating within about 50% of the rated Xmax if you wanna keep the distortion low on a nonlinear driver (like this 10" Beta). Excursion is related to the SPL and the low frequency corner, so really you should start off by determining what kind of output and bandwidth you need....and then finding a driver that can handle that performance spec. Once you find a best fit driver, then you can start trying to optimize the alignment...the nice thing about alignments though is that the driver manufacturer has already maximized the performance of the driver to a particular alignment - which means going off the recommended cab specs is a very valid approach... Quote Link to comment Share on other sites More sharing options...
Daddy Dee Posted February 21, 2008 Author Share Posted February 21, 2008 Mike, Thanks for your work here. On the driver, we're not locked in to it. It just has a lower frequency in it's spec than the twelve, I think. Also liked it being slightly smaller than the twelve, but it's not a big deal to use the twelve. What we're hoping for in this forum is to get some good advice and build it right the first time. I'm hearing a pretty strong recommendation for using the twelve over the ten. Quote Link to comment Share on other sites More sharing options...
djk Posted February 21, 2008 Share Posted February 21, 2008 http://www.loudspeakersplus.com/images/WN-12S.pdf Put this in 2~2.5 cu ft and tune to 50hz. $70, more efficient, flatter, 5.6mm x-max (coil overhang plus 1/4 gap height method). Quote Link to comment Share on other sites More sharing options...
HarryO Posted February 21, 2008 Share Posted February 21, 2008 DD, When I built my Wallrus (Cornwall volume and guts) I started out with the Cornwall port size not giving it a second thought. NOPE! Didn't work out. I went to the calculators and I still was NOT happy with the results. It came down to trial and error finally with about a 13% reduction in Cornwall port size to acheive the results I wanted. No port tubes either after I got the sound I wanted. Cabinet volume is NOT the only factor as far as I can tell. Shape may have a bit to do with it also. I'm no cabinet expert yet but I'm building about a half dozen different cabinets using the same basic components and volume and the shape is different in each. I've had to "fine tune" the port sizes in EACH cabinet. No help to you except don't expect perfect results by the calculator. Play with it a bit and see what happens. Harry Quote Link to comment Share on other sites More sharing options...
pzannucci Posted February 21, 2008 Share Posted February 21, 2008 Daddy Dee, HarryO and Mike are right. Build the cabinet so it can be fine tuned, changing port size and depth. Just because a cabinet models with a response you like, it doesn't mean that you will like the sound. Depending on the size of the box and the tuning, the woofer and port will react differently. It may come down to boomy vs. tight. Also you will need to make trade-offs between depth, size, and efficiency. Are you trying to have a very efficient speaker that will extend low in the bass? Quote Link to comment Share on other sites More sharing options...
Daddy Dee Posted February 21, 2008 Author Share Posted February 21, 2008 djk, HarryO, Pzannucci, Thanks for the advisement here. These are things we definitely need to be up on our radar screen. Quote Link to comment Share on other sites More sharing options...
Daddy Dee Posted February 21, 2008 Author Share Posted February 21, 2008 Put this in 2~2.5 cu ft and tune to 50hz. $70, more efficient, flatter, 5.6mm x-max (coil overhang plus 1/4 gap height method). Dennis, Would you mind saying more about your post. I'm not sure I'm understanding. The box volume of 2 - 2.5 feet I understand. How is it tuned to 50hz? Does the port do that? Also, the $70 is referring to a particular woofer? The 12' Eminence Beta? Quote Link to comment Share on other sites More sharing options...
djk Posted February 21, 2008 Share Posted February 21, 2008 http://www.loudspeakersplus.com/images/WN-12S.pdf The port is tuned to 50hz. Quote Link to comment Share on other sites More sharing options...
Marvel Posted February 21, 2008 Share Posted February 21, 2008 DD, That's a PAudio woofer, and right now they have it for $70 (I had loked at the ten incher by mistake). Bruce Quote Link to comment Share on other sites More sharing options...
Daddy Dee Posted February 21, 2008 Author Share Posted February 21, 2008 ok. got it! Thanks. Quote Link to comment Share on other sites More sharing options...
pzannucci Posted February 22, 2008 Share Posted February 22, 2008 Dennis, Would you mind saying more about your post. I'm not sure I'm understanding. The box volume of 2 - 2.5 feet I understand. How is it tuned to 50hz? Does the port do that? Also, the $70 is referring to a particular woofer? The 12' Eminence Beta? Daddy Dee, Remember that: Box Volume + Port Size + Port Length/Depth = Box Tuning Quote Link to comment Share on other sites More sharing options...
Daddy Dee Posted February 22, 2008 Author Share Posted February 22, 2008 Thanks Peter. Quote Link to comment Share on other sites More sharing options...
Tony Reed Posted February 26, 2008 Share Posted February 26, 2008 Dennis, Would you mind saying more about your post. I'm not sure I'm understanding. The box volume of 2 - 2.5 feet I understand. How is it tuned to 50hz? Does the port do that? Also, the $70 is referring to a particular woofer? The 12' Eminence Beta? Daddy Dee, Remember that: Box Volume + Port Size + Port Length/Depth = Box Tuning OK... let's say we've settled on box volume. How do you calculate port size and length for a certain frequency? Thanks, Tony Quote Link to comment Share on other sites More sharing options...
pzannucci Posted February 26, 2008 Share Posted February 26, 2008 Tony, There are numerous free calculators on the net to give you the number of square in/cm of a port, and the length of the port to get you to a particular tuning based on the box volume. You just have to make sure you have good sound reasons as to why you want to tune the box to that particular frequency. Some tune around the FS of the driver to minimize excursion though if you get signals lower than that tuning point, the driver unloads and can exceed safe movement. Others might tune the port lower in an attempt to add a few Hz to the bottom end. Larger box, deeper bass, more efficient base, etc... they are all tradeoffs. You have to decide which you can live with. Quote Link to comment Share on other sites More sharing options...
djk Posted February 27, 2008 Share Posted February 27, 2008 The P-Audio WN-12S is 97.7dB/2.83V/1M midband. In a 2.5 cu ft box tuned to 50hz via two 4" ID ports 6.5" long it will be -3dB at 50hz and handle 250W without exceeding x-max. Quote Link to comment Share on other sites More sharing options...
Daddy Dee Posted February 27, 2008 Author Share Posted February 27, 2008 Dennis, You are da man! I seriously appreciate that calculation and the rec on the Paudio woofer. Quote Link to comment Share on other sites More sharing options...
Tony Reed Posted February 27, 2008 Share Posted February 27, 2008 Yep... that is exactly the info we needed. Thanks to all, Tony Quote Link to comment Share on other sites More sharing options...
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