idxtreme Posted November 21, 2006 Share Posted November 21, 2006 Hi! Newbe here to this site. A long time ago I built a set of cornwall clones using k33s from Speakerlab not knowing what it was called at the time but I was really in to it in highschool. After many years of parties and abuse I was tired of lugging them around. So I removed the drivers and threw away the boxes. 27 years later I still have them! Now I was thinking about building the boxes (k33s) but as subs disguised as end tables. Then maybe use the speakerlab wa750s and wa5000s as sats. I also have a pair of bose 301 IIs, an old Toshiba 7150 (150x150 watts @8ohms) a SAE P10 amp (100x100 watts @ 8 ohms). Eventually I would like to buy a cheap Active crossover (Alto perhaps?) and a 7.1 reciever and additional speakers so I can tri-amp and surround sound my room. I know I'll get flamed here. I listed everything I have for you to comment on. This is for fun and to build a cheap, somewhat hidden but good sounding home theater type family room that is yet to be drywalled. Its 24' wide x 20' deep x 8' high. I have pre-run several RG6 cables in PVC going across the room front to back for the big screen. I'm not sure where to run the speaker wire yet since they may go on the floor, on or in the wall or ceiling. So, what do you think of Cornwalls as subs? How should they be built? Can they fire downward like 10" off the floor? I like having no passive crossovers. The new HT recievers have mics and EQs plus pre-outs and main-ins on every channel. The active crossovers have timing adjustments, phase adjustments. output adjustments. All that plus my old junk? I think it just might work! OK. Flame away! Quote Link to comment Share on other sites More sharing options...
Duke Spinner Posted November 21, 2006 Share Posted November 21, 2006 No Quote Link to comment Share on other sites More sharing options...
colterphoto1 Posted November 21, 2006 Share Posted November 21, 2006 I don't think that will be sufficient bass response as a 'sub'. Besides the K33 isn't rated for the type a punishment that using it as a HT sub would deliver. Michael Quote Link to comment Share on other sites More sharing options...
Guest " " Posted November 21, 2006 Share Posted November 21, 2006 idxtreme One of the issues with the speakerlab version of the k-33 is that it is 8 ohms. An 8 ohm speaker is usally not used as a sub woofer, and is finding less favor as even a woofer. Another factor in using a woofer as a sub woofer is the response curve usally drops off pretty rapidly at the lower frequencies....this is due to the mechanics of the woofer that allows it to reach 400hz and above. A good sub woofer speaker has a consistent response curve near it FS frequency and usally rolls off pretty rapidly over 200hz. Quote Link to comment Share on other sites More sharing options...
idxtreme Posted November 21, 2006 Author Share Posted November 21, 2006 So what cabinet design and woofer would make a good sub/end table? Or is this stupid? And what about the rest of my stuff? What would you do? I like the idea of efficient use of floor space and hiding things. Also where can I find the Q's for these woofers? I may build the clones anyway. Your ideas are appreciated. Quote Link to comment Share on other sites More sharing options...
DrWho Posted November 21, 2006 Share Posted November 21, 2006 Nominal impedance has absolutely nothing to do with the feasibility of using a driver for low frequencies, nor does the ability of the driver to play higher in frequency. A great example would be the KW-120's: arguably one of the best subwoofer systems out there...(it can get up to 2kHz no problem and they are 8 ohm drivers). The things limiting high frequency extension are the inductance of the voice coil and the stiffness (not mass) of the cone. Mass really only affects the efficiency of a target design. Often extra mass and a more robust voice coil (higher inductance) are used to extend the low frequency extension without changing the compliance of the suspension (the advantage being a tighter suspension can keep itself aligned in the gap better). It's a less expensive alternative to just building the suspensions to a higher tolerance (or increasing the gap size which also reduces efficiency). But this doesn't mean high inductance and a non-stiff cone are required for subs. As far as the K33 - the motor doesn't provide enough displacement to be used as a subwoofer. A 15" driver will need at least 20mm of excursion to provide any decent output (The K33 is only around 8mm). The frequency response of the system can be adjusted for with EQ - so ultimately you're looking for the most displacement with the most efficiency. There are plenty of alternative drivers out there that would yield good results in a custom down-firing coffee table. The important criteria will be "how much are you willing to spend?" and "how big can the enclosure be?" (bigger being better - Hoffman's Iron Law). Here are a few places you might try picking products from: http://www.ascendantaudio.com/ (assassin drivers) http://www.tcsounds.com/ http://www.partsexpress.com/ (dayton titanic or dayton DVC drivers) Quote Link to comment Share on other sites More sharing options...
chops Posted November 21, 2006 Share Posted November 21, 2006 Nominal impedance has absolutely nothing to do with the feasibility of using a driver for low frequencies, nor does the ability of the driver to play higher in frequency. A great example would be the KW-120's: arguably one of the best subwoofer systems out there...(it can get up to 2kHz no problem and they are 8 ohm drivers). I just want to say "Thanks DrWho"! I was going to comment on that whole 8 ohm thing, but saw that you already did, and said it better than I was going to. [] Also, I would just like to say that I back up those Dayton DVC drivers very strongly. If properly implemented, they can deliver excellent results! http://chops.tzo.com/subproject.htm Quote Link to comment Share on other sites More sharing options...
Guest " " Posted November 21, 2006 Share Posted November 21, 2006 "Nominal impedance has absolutely nothing to do with the feasibility of using a driver for low frequencies" If you have questions, or need points clarified, I 'll be happy to do so. An 8 ohm woofer would need twice the power and have less SPL for a given amp's output power than a like 4 ohm woofer. The issue of design in terms of bandwidth, has to do with the weight of the moving mass for a targeted power handling spec. As a result, woofers that are optimized to generate high SPL and good roll off and decent power handling at lower portions of the sound spectrum, are usally to heavy of a moving mass to do well at the upper portions. If you have any other questions of my opions, by all means, let me know. Quote Link to comment Share on other sites More sharing options...
chops Posted November 21, 2006 Share Posted November 21, 2006 "Nominal impedance has absolutely nothing to do with the feasibility of using a driver for low frequencies" If you have questions, or need points clarified, I 'll be happy to do so. An 8 ohm woofer would need twice the power and have less SPL for a given amp's output power than a like 4 ohm woofer. My Dayton's are 8 ohms. Quote Link to comment Share on other sites More sharing options...
Guest " " Posted November 21, 2006 Share Posted November 21, 2006 The speaker on the left is a speakerlab clone of the k-33. The speaker on the right is a k-33. The speaker on the left would need more power from an amp than the speaker on the right for the same spl. The speaker on the left would generate less output than the speaker on the right for the same given amp power level. The speaker on the left is an 8 ohm woofer The speaker on the right is a 4 ohm woofer. This is the best I can clarify, and based on that, I would not use the speakerlab clone of the k-33 for a sub woofer driver. Quote Link to comment Share on other sites More sharing options...
chops Posted November 21, 2006 Share Posted November 21, 2006 The speaker on the left would need more power from an amp than the speaker on the right for the same spl. The speaker on the left would generate less output than the speaker on the right for the same given amp power level. No necessarily. If both drivers are rated at say 98dB @ 1w/1m, then it still doesn't matter what impedence they are. IOW, 98dB @ 1w is 98dB @ 1w. BTW, I bet those chairs are cold as hell durring the winter season! [] Quote Link to comment Share on other sites More sharing options...
idxtreme Posted November 21, 2006 Author Share Posted November 21, 2006 I thought that the movement of a woofer to produce a 20hz signal was like .125"? Are signals below that of any use? Please elaborate? Quote Link to comment Share on other sites More sharing options...
DrWho Posted November 21, 2006 Share Posted November 21, 2006 An 8 ohm woofer would need twice the power and have less SPL for a given amp's output power than a like 4 ohm woofer. By that logic, every speaker in the world should have an impedance as low as possible....heck, why not target a 2 ohm impedance? or how bout 1 ohm? 1/2 ohm??? The limiting factor of motor strength is the amount of current flowing through the voice coil. Sure, it takes "twice as much power" for an 8 ohm driver, but the current draw is going to be the same. It just means a higher voltage is required...and voltage is easy to obtain. Quote Link to comment Share on other sites More sharing options...
BEC Posted November 21, 2006 Share Posted November 21, 2006 use it. Quote Link to comment Share on other sites More sharing options...
idxtreme Posted November 21, 2006 Author Share Posted November 21, 2006 Where can I find the Q measurements for these woofers as well as others for comparison? I want to build something. I D/L some software (WinISD) to play with but these woofers are not in the database. BTW thanks for all of your input so far. You guys are great! Quote Link to comment Share on other sites More sharing options...
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