SUPPORT FORUMS FOR DECWARE SPEAKER PLANS >> Housewrecker Support Forum >> advice on these drivers

Message started by rondawg72 on 04/06/06 at 19:04:06

Title: advice on these drivers
Post by rondawg72 on 04/06/06 at 19:04:06

i picked up these two drivers about 12 years ago in a trade with my brother....they have never been hooked up and are in original packaging.....they came with a couple of recommended enclosure designs that i dont care for - i wanted to do an infinite baffle with them but ive been told by many expierienced people that these drivers are not suitable for such an application....they have all reccommended a "ported" enclosure which brought me here - the home wrecker plans really intrigue me and i want to see if anyone who knows what the driver parameters mean in relationship to whether or not they would be suitable for this enclosure - i will list the only info i have on them....they must no longer be manufactured because i can find very little info on them....and yes i know Radioshack woofers arent the most desirable...but im willing to build the box and see how they perform unless someone tells me it not worth the effort...ok   here is the info i have:

Radio Shack Cat, No. 40-1309 (18" Subwoofer)

Nominal Impedance........................... 8 ohms
DC Resistance (RE)............................ 6.83 ohms
Free Air Response............................. 16.5 hz
Equivalent Air Volume(VAS)............... 41 Ft3
Moving Mass (Mms)........................... 192.6 Grams
Mechanical Q (QMS)........................... 1.986
Electrical Q (QES)............................... 0.225
Total Q (QTS)..................................... 0.20
Peak Power Handling........................ 200 Watts
Peak-to-Peak Linear Excursion(XD)... 6.1 mm
Gap Flux Density(BG)......................... 7850 Gauss (+/- 200 Gauss)

can anyone advise me on using these in this application?? - also the room that this will box will be in has 15' ceilings....does this matter with the top mounted port?? it seems like there will be alot of travel before the sound hits its first "reflective" plane?

i want to load both drivers in one HWK and i have 2 Marantz ME-500 amps to run them - does this all add up to a smile on my face or will i be dissapointed.....any help will be appreciated

Title: Re: advice on these drivers
Post by rondawg72 on 04/10/06 at 11:21:10

well...its been four days since i posted this....and in the mean time ive read evey single line of evey thread on this HWK forum....and i feel good because alot of people seem to think that the design makes Goliaths out of David drivers....IE - cheap woofers do well in this im a little freaked out because there seem to be as many people out there with negative expieriences as positive...i worry about the overall mass of these cones in the vertical alignment.....and i do realize that alot of people who had problems expierimented with the design...port location and chamber size.....i dont know.....this board obviously has a long response time....probably because you all have already built and are too busy guess ill just build the damn thing and see what happens!! -- i really want to find a good enclosures for these speakers....they were basically free....and they are "new" (old but never used)....the xmax (3mm) does not allow IB...which is what i really wanted......traditional enclosures for these are as big as the HWK but terribly ineffective......maybe i should just ebay these things and step into some Infinite Baffle drivers....again any advice from anyone would help settle my mind

Title: Re: advice on these drivers
Post by 60ndown on 04/10/06 at 14:17:48

its too hard to say for sure, build a housewrecker, try your drivers, if they dont work get different ones ;D but you should only build the hw if you want alot of bass in a big room.

Title: Re: advice on these drivers
Post by rondawg72 on 04/10/06 at 19:04:17

ty...well it is a fairly big room...thats what attracted me to the plans...the footprint of the room isnt that big.....17'X20'...basiclly a big cube....but it has a lot of volume.....ceilings....15' that peak to 18' - again ty....i have already decided to build it over the 3 day weekend....i guess i was originally wanting advice because if these dont work out and i have to buy other drivers then they would be 15" not 18"...the 18" woofers are so expensive and the options are fewer than those of the smaller i would basically be throwing this enclosure away if not happy....although the side panels could be salvaged and cut down....but anyway...just thinking out loud.....from all that ive read its a gamble im willing to take at this point!

Title: Re: advice on these drivers
Post by Bob on 05/05/06 at 22:14:10

Well Ron, Status report please.  :)

(Not sooo many periods this time)


Title: Re: advice on these drivers
Post by John in CR on 05/05/06 at 22:51:29

Sorry I missed the thread, because they won't work in the HWK, Vas way way too high.  The specs make you think they'd be a great HT sub driver, but the super high Vas means giant box to get extension and with the very low Qts their response falls off with out the air spring of a small box.

If you want HT extension, then you were correct about wanting to go IB.  It's not optimum, but for those drivers optimum is rolling off steeply below 40-50hz in smallish boxes.  Sell them and get more appropriate drivers is your best bet.

Title: Re: advice on these drivers
Post by rondawg72 on 05/06/06 at 17:46:02

Sorry Bob for leaving you hanging. John probably does not remember but i wrote him personally asking about the drivers and he explained to me many reasons why i would be dissapointed using these woofers in this enclosure, so i never built it. At the moment im just using an old box i had built a few years ago for a mustang i used to have, its got a couple of 10" kickers in it. It is both unattractive and weak sounding with the system, but it is what i - ive been scouring sites looking for a deal on some suitable IB drivers considering that would be the most desirable situation for me - i have the perfect location for this setup and by placing my "car box" along that wall, the acoustics seem desirable. Very soon i think i will just get ahold of 4 of the partsexpress IB 15's and get it over with.

All hope is not lost with these drivers yet - I've found myself wrapping my brain around MLK's transmission line pages. I must admit that i find alot of it confusing but i think i have the basic idea figured out, and i have really high ceilings so i think i may expieriment with a transmission line just to see how they perform. I drew out a basic plan on "paint" and i will include it, i wanted to iso load the enclosure because of the woofers being low end, but alot of guys are telling me that there is zero advantage to iso loading these types of enclosures so im still thinking it through. Luckily a close friend of mine is a site foreman for a concrete crew and he has offered to order 40' or so of 18" sonotube on the next job and bring it by my house for me to play with, so i can try some different ideas and see what results i get. Others have suggested that i put a speaker 1/3 of the way in a setup to make a "Bose Cannon", but i dont know about that - when i do get an opportunity to try some stuff out ill let you know.

has anyone ever done any work with these lines??
im just wondering what kind of results i can expect and again if these drivers are even suitable.

again i will post my rough idea and leave it open for - i do appreciate all of yours expierience with these things and will always respect your adivce because it beats wasing alot of time and money to just be unhappy with the results.

my microsoft paint skills are as rough as my knowledge of speaker mechanics so please keep an open

that may be hard to see so here is the link:

well hmmm - i cant get it to get large enough for you guys to see, i wish i could just insert the file, But it is basically a 17' line with one fold in it. I plan to attach 18" sonotube directly to the back of one of the woofers and gradually put a 90 degree fold in the line @ the 5' mark and let the remaining 12' run out like a stack firing towards the ceiling. I wanted to build a minimal sealed box at the front of this woofer to house the other woofer to iso load it to help control the cone movement because of the "cheapness" of these speakers. and i was going to continue these box measurements all the way to house the horizontal run of the tube to anchor it and make it stable. the only drawback to this is that i only really have one choice for placement in the room. it would be located behind behind my tv and center channel in the middle of the room running up the wall towards the peak in the ceiling. My LCD is mounted on a cantilever mount so i can easily manuever the arm around the tube to recenter it to my viewing position.

ok thats enough

Title: Re: advice on these drivers
Post by bassboy on 05/06/06 at 20:14:52

Ron, in reply to your question about similar projects, there are at least a few.  The notable one, closest to your project is "El Pipo".  It is a good article, they used 21" drivers and a 12 foot long 24" sonotube.

I recently got a lot of good advice about tl's in the home theatre forum (of all places), specifically the 1952 Jensen Transflex, a 16 foot line using a 15" driver, but it is rectangular.

Title: Re: advice on these drivers
Post by Bob on 05/08/06 at 16:58:26

Ron, that looks like a fun project, keep us posted.  ;D


Title: Re: advice on these drivers
Post by rondawg72 on 08/13/06 at 16:45:22

again....same as the cheapo 12" HWK i was planning i ran into to little free time this summer to follow through....and these woofers i ended up swapping with a co-worker for a kegerator for my game any ideas i had with these drivers are dead to me - im currently waiting on 4 18" woofers from Mach 5 audio per this thread started by Gexter to use in an IB -- i will definately be posting pics and results on this in another forum;action=display;num=1155352635

Title: Re: advice on these drivers
Post by gexter on 08/14/06 at 01:46:45

post em in the IB thread too!!!

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