What I have is a Polk XT-12 with -new box and woofer. It is 60L Vb minus my port and toroid (@ 55L). Port is 10cm X 30cm long. I found a good web calculator ....
http://www.mh-audio.nl/Calculators/BRH.html .
I don't know the T/S parameters of the Polk XT-12. It works , but I heated up the VC - I was a dummy and Xmax'ed it with my DIY plate amp. (photo 1) .
Amp worked TOO good @ 14hz , I smelled the VC after 20 minutes. I just wanted to see the worst case load for the new amp.
Using that MH-audio calculator with many Parts-Express drivers and suggestions , it seems to be valid (very close) as far as box tuning.
The NEW driver I want looks cool (a piston) and fits the box - A Dayton LS12-44. https://www.parts-express.com/Dayto...ofile-Subwoofer-Dual-4-Ohm-295-253?quantity=1
In (photo 2) I plugged in all my T/S parameters and get roughly a 32hz F3 (with the smaller Vb). I actually get gain between 40-60hz. Is that normal ?
I would not mind some free output at 45hz , I listen to classic rock mostly.
The Dayton can also be wired as a 2R in parallel , I have a 30-0-30 trafo , I'm sure my REAL amp could drive that with this lower voltage. Would running
at the lower Imp. change my T/S params ?? Running in series (8R) , I'm not too displeased . The original XT Polk driver does not seem to have much output below 30hz
with actual in-room testing, Polk says the OEM sub is usable to 26hz .... I'm not sure I even trust Polk , they make junk these days .... the original amp was a joke (failed).
Thanks...
PS- I know my port is barely sufficient for that 10mm Xmax , but the amp might not push the dayton much more than 5-7mm.
The Dayton = 250W .... my amp is a 4 output device 125W unit,
http://www.mh-audio.nl/Calculators/BRH.html .
I don't know the T/S parameters of the Polk XT-12. It works , but I heated up the VC - I was a dummy and Xmax'ed it with my DIY plate amp. (photo 1) .
Amp worked TOO good @ 14hz , I smelled the VC after 20 minutes. I just wanted to see the worst case load for the new amp.
Using that MH-audio calculator with many Parts-Express drivers and suggestions , it seems to be valid (very close) as far as box tuning.
The NEW driver I want looks cool (a piston) and fits the box - A Dayton LS12-44. https://www.parts-express.com/Dayto...ofile-Subwoofer-Dual-4-Ohm-295-253?quantity=1
In (photo 2) I plugged in all my T/S parameters and get roughly a 32hz F3 (with the smaller Vb). I actually get gain between 40-60hz. Is that normal ?
I would not mind some free output at 45hz , I listen to classic rock mostly.
The Dayton can also be wired as a 2R in parallel , I have a 30-0-30 trafo , I'm sure my REAL amp could drive that with this lower voltage. Would running
at the lower Imp. change my T/S params ?? Running in series (8R) , I'm not too displeased . The original XT Polk driver does not seem to have much output below 30hz
with actual in-room testing, Polk says the OEM sub is usable to 26hz .... I'm not sure I even trust Polk , they make junk these days .... the original amp was a joke (failed).
Thanks...
PS- I know my port is barely sufficient for that 10mm Xmax , but the amp might not push the dayton much more than 5-7mm.
The Dayton = 250W .... my amp is a 4 output device 125W unit,
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Yes.
Yes, post #3 shows the T/S parameter changes in a dual voice coil driver wired series vs parallel:
https://www.diyaudio.com/community/...-series-wirings-affect-t-s-parameters.392531/
Thank you.
BTW - the original polk driver is quite stiff. I have read that stiff = lower Vas. Some of the VERY inefficient car audio drivers I modeled with
30'ish Vas did give me a flat response with my small Vb. But I decided 83-85db SPL was in the realm of 1/2KW class D car audio. I only have
a 120W A/B DIY plate amp.
Subs have quite deceptive ratings these days .... https://www.sweetwater.com/store/detail/KRK12SHO--krk-12sho-12-inch-powered-studio-subwoofer
1500$ sub with a 400W amp ??? I looked the amp up - 2 pair BJT like mine , maybe 200W with the calculated BJT SOA.
At least Dayton (hopefully) is honest. I have 8" Dayton woofers rated at 100W , they can do that and more.
BTW - the original polk driver is quite stiff. I have read that stiff = lower Vas. Some of the VERY inefficient car audio drivers I modeled with
30'ish Vas did give me a flat response with my small Vb. But I decided 83-85db SPL was in the realm of 1/2KW class D car audio. I only have
a 120W A/B DIY plate amp.
Subs have quite deceptive ratings these days .... https://www.sweetwater.com/store/detail/KRK12SHO--krk-12sho-12-inch-powered-studio-subwoofer
1500$ sub with a 400W amp ??? I looked the amp up - 2 pair BJT like mine , maybe 200W with the calculated BJT SOA.
At least Dayton (hopefully) is honest. I have 8" Dayton woofers rated at 100W , they can do that and more.
Right, so the higher the Vas combined with the bigger the box = more efficiency. Attached max sealed, vented box efficiency charts, efficiency - sensitivity conversion link.
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Were you happy with the sound of the Polk before it blew? I suspect a lot of commercial subs are tuned similarly to the response of that Dayton sub in 55L. FWIW, I'm running a single GRS 12SW-4HE(sensitivity:84db) off of 150-ish watts and still need to keep the AV receiver sub out at -6db. Granted the room is only 11.5' x 12.5'. I don't know how big of a space you're planning on using it, but just because a sub can take 500-1000w doesn't mean you'll need that much to reach your desired output.
Yes , I liked the Polk sub driver . But I did buy the Dayton. The woofer worked but buzzed with more power , the voice coil was glued crooked.
At least parts - express refunded me my whole 135$ ... without even asking for the return. They must know of the (new) made in china build quality
and expected X percent failure. My Taiwan 8" dayton drivers are 10 years old - perfect .... no more Dayton.
I even cut the cone/spider out (good quality) except for a coil wire sticking out and the whole former being crooked !!
I now bought a KRK cast frame V12S woofer - part # (12inc.WOFK12202.bajo altavoz.WOFK12201). 55$ overstock.
I know the ...
Qms 1.6 / Qes - .78
Qts - .53 Fs - 33hz
Re - 3.2ohm , same as the Polk.
I wish I knew the Vas.
The complete V12S sub is commercial , and it's OEM box has an internal volume of Vb/70L. (it's vented).
Ohhh , it even matches my yellow Kevlar 5.5" satellites. I'll try it.
OS
At least parts - express refunded me my whole 135$ ... without even asking for the return. They must know of the (new) made in china build quality
and expected X percent failure. My Taiwan 8" dayton drivers are 10 years old - perfect .... no more Dayton.
I even cut the cone/spider out (good quality) except for a coil wire sticking out and the whole former being crooked !!
I now bought a KRK cast frame V12S woofer - part # (12inc.WOFK12202.bajo altavoz.WOFK12201). 55$ overstock.
I know the ...
Qms 1.6 / Qes - .78
Qts - .53 Fs - 33hz
Re - 3.2ohm , same as the Polk.
I wish I knew the Vas.
The complete V12S sub is commercial , and it's OEM box has an internal volume of Vb/70L. (it's vented).
Ohhh , it even matches my yellow Kevlar 5.5" satellites. I'll try it.
OS
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The Polk did not blow , but I smelled the voice coil (very little) while testing it. it still works good , and measures 3.2R. I don't see any coloration on the VC.
If like the KRK , I'll sell it (polk) for 10$ instead of burying it. I think my amp is just a bit too powerful for it. I must of ran 200W+ below the Fs , where the impedance was low. I won't test the KRK at 10hz/200W for 1/2 hour , I learned.
Measure its effective diameter (D), i.e. from c-t-c of surround and we can 'close enough' reverse engineer it.
Thank you , I should receive it Saturday.
I tried to find out more about it (the woofer). The KRK 12S HO is the same woofer with a larger VC (75mm). By KRK's Vb and port config ,
I did get F3's close to OEM specs with Vas's (70-100L).
No manufacturer size specs. By the picture , I would estimate 240mm of the yellow Kevlar.
I tried to find out more about it (the woofer). The KRK 12S HO is the same woofer with a larger VC (75mm). By KRK's Vb and port config ,
I did get F3's close to OEM specs with Vas's (70-100L).
No manufacturer size specs. By the picture , I would estimate 240mm of the yellow Kevlar.