Well I had particular questions on this little project of mine, and figured a forum post would be the way to go. Here is some background:
I have a promedia 2.1 system from 12 years ago. The foam surrounds on the subwoofer deteriorated and it led to a blown woofer the other day. The satellites still work fine. Instead of getting a straight replacement for the woofer I started reading about a dayton audio sub:
Dayton Audio DC160-8 6-1/2" Classic Woofer
people have used this as a decent replacement, they seem to like it. The promedia amp puts out 6 ohms, and this woofer is 8 ohms. I found one 6 ohm woofer and it didn't seem of that good of quality. This Dayton woofer is around 26 bucks with shipping so it's worth it to me. But now here are my questions. I ran it through a box volume design calculator with it's thiele parameters and it's telling me that I can do sealed with 0.4 ft^3 and a qtc of 0.55. My promedia box is that exact volume, so this was the QTC that will work for sealed. So the question is should I try to do this sealed sub with a qtc that low, or just try ported given there is already a port? But with this woofer they are calling for 0.63 ft3 and a port length of 11 inches (quite close in length and width (2 inches) to the original. So I seem limited to a ported box that is .23 smaller than what it is supposed to be, and a sealed box with a qtc that is quite low. I'm wondering if I should just give it a shot for the 27 bucks or consider another woofer that might be more suitable for that volume box. I'm not opposed to putting an 8 inch in (sawing a new hole), but the amp is limited to 50 watts RMS at 6 ohms. The MDF of the box is 1/2 inch, so it seems thick enough for an 8.
Here is some other information. The woofer is rated at 50 watts rms (and the amplifier is too). So it seems to be a decent enough pairing, but this amp gives that out at 6 ohms. It's sold as a woofer, not a subwoofer on the PE website. The EBP of this woofer is 93, so that would seem that a ported box would be best for this woofer, right? But close enough to that both range to use for sealed?
Some more background info..... I tend to prefer sealed subs for my home systems, and car audio. This project seemed like a good opportunity to make a small sealed sub, and perhaps experiment with the sound of a lower QTC system. But it's a 6.5, a woofer (not sub), low powered, and perhaps might not match up well with the crossover point set from the amp. I believe it's 100hz? Maybe someone can confirm that, I read it somewhere? the Dayton claims: Frequency Response30 to 4,000 Hz
Some other thoughts on the project:
1. I could just stick it in when I get the speaker and see how it sounds ported.
2. I can then sealed the port and see how it does sealed.
3. I can put in polyfill and lower the QTC even more?
4. Then if I don't like that and decide the ported route is one I don't want to go, I can put some larger braces in and see how it sounds with a higher QTC.
I guess the problem I see are with the permanent changes, as they likely can't be undone easily (braces).
To me a lot of this is fun, and the promedia doesn't have too much value for me anymore. If I can turn it into something I enjoy for a bit longer that would be nice. I also didnt' state that I would likely only use this system for computer speakers, and for music. I like electronic, hip-hop, and other less bass heavy music across a wide range of listening. I don't need a high volume, just something that sounds good in a small room.
Any thoughts on this would be greatly appreciated. I'm not in a rush to do this, so I can give it more thought.
I have a promedia 2.1 system from 12 years ago. The foam surrounds on the subwoofer deteriorated and it led to a blown woofer the other day. The satellites still work fine. Instead of getting a straight replacement for the woofer I started reading about a dayton audio sub:
Dayton Audio DC160-8 6-1/2" Classic Woofer
people have used this as a decent replacement, they seem to like it. The promedia amp puts out 6 ohms, and this woofer is 8 ohms. I found one 6 ohm woofer and it didn't seem of that good of quality. This Dayton woofer is around 26 bucks with shipping so it's worth it to me. But now here are my questions. I ran it through a box volume design calculator with it's thiele parameters and it's telling me that I can do sealed with 0.4 ft^3 and a qtc of 0.55. My promedia box is that exact volume, so this was the QTC that will work for sealed. So the question is should I try to do this sealed sub with a qtc that low, or just try ported given there is already a port? But with this woofer they are calling for 0.63 ft3 and a port length of 11 inches (quite close in length and width (2 inches) to the original. So I seem limited to a ported box that is .23 smaller than what it is supposed to be, and a sealed box with a qtc that is quite low. I'm wondering if I should just give it a shot for the 27 bucks or consider another woofer that might be more suitable for that volume box. I'm not opposed to putting an 8 inch in (sawing a new hole), but the amp is limited to 50 watts RMS at 6 ohms. The MDF of the box is 1/2 inch, so it seems thick enough for an 8.
Here is some other information. The woofer is rated at 50 watts rms (and the amplifier is too). So it seems to be a decent enough pairing, but this amp gives that out at 6 ohms. It's sold as a woofer, not a subwoofer on the PE website. The EBP of this woofer is 93, so that would seem that a ported box would be best for this woofer, right? But close enough to that both range to use for sealed?
Some more background info..... I tend to prefer sealed subs for my home systems, and car audio. This project seemed like a good opportunity to make a small sealed sub, and perhaps experiment with the sound of a lower QTC system. But it's a 6.5, a woofer (not sub), low powered, and perhaps might not match up well with the crossover point set from the amp. I believe it's 100hz? Maybe someone can confirm that, I read it somewhere? the Dayton claims: Frequency Response30 to 4,000 Hz
Some other thoughts on the project:
1. I could just stick it in when I get the speaker and see how it sounds ported.
2. I can then sealed the port and see how it does sealed.
3. I can put in polyfill and lower the QTC even more?
4. Then if I don't like that and decide the ported route is one I don't want to go, I can put some larger braces in and see how it sounds with a higher QTC.
I guess the problem I see are with the permanent changes, as they likely can't be undone easily (braces).
To me a lot of this is fun, and the promedia doesn't have too much value for me anymore. If I can turn it into something I enjoy for a bit longer that would be nice. I also didnt' state that I would likely only use this system for computer speakers, and for music. I like electronic, hip-hop, and other less bass heavy music across a wide range of listening. I don't need a high volume, just something that sounds good in a small room.
Any thoughts on this would be greatly appreciated. I'm not in a rush to do this, so I can give it more thought.
It's a bit boring, but you can check how a woofer will perform in that enclosure before building anything. You can simulate what the frequency response will be with WinISD for example. If the response it OK, then you are good to go. You can also see what the effect of blocking the port will be, decreasing the air volume etc. Note that the Xmax of the Dayton woofer is a bit on the low side (3 mm) so it cannot go very loud.
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An amp doesn't put out an impedance, but it's the range in which it performs the most efficiently. An eight ohm woofer on a six ohm rated amp will work fine. It just won't put out that much power but this is negligible knowing impedance changes with frequency and that there's a tolerance
I have to agree, 3 mm is a bit low. The original klipsch woofer didn't do much of anything else though did it?
The original was quite loud for it's size, I used it for music for years. I didn't quite like the sound, maybe that was because it was ported and seemed to have that sound that a lot of car audio systems have, kind of a one note wonder sound.
I was looking at this woofer:
Dayton Audio DC200-8 8" Classic Woofer
Thiele-Small Parameters:
Resonant Frequency (Fs)30.3 Hz
DC Resistance (Re)6.41 ohms
Voice Coil Inductance (Le)2.32 mH
Mechanical Q (Qms)3.06
Electromagnetic Q (Qes)0.49
Total Q (Qts)0.42
Compliance Equivalent Volume (Vas) 1.61 ft.³
Mechanical Compliance of Suspension (Cms)0.77 mm/N
BL Product (BL)9.5 TmDiaphragm Mass Inc. Airload (Mms)36.1g
Maximum Linear Excursion (Xmax)4.5 mmSurface Area of Cone (Sd)211.2 cm²
For the volume of the existing box 0.4 ft^3 I would get a QTC of 0.93 with this woofer. Quite a bit higher than I wanted, but perhaps stuffing it with half a pound of polyfil will lower the QTC into an acceptable range to use this for low to mid volume music? I don't expect much out of this, it's just kind of fun for me to imagine a modded system that will sound as good as the original or perhaps even better. I do prefer sealed over ported usually and so this route seemed like a good idea, esp if the woofer is now a step up in size/quality than the original. I'm just hesitant to throw in this 8 in this sealed box with a QTC that high. I guess I would have to hear it to truly know if I like it, right?
I was looking at this woofer:
Dayton Audio DC200-8 8" Classic Woofer
Thiele-Small Parameters:
Resonant Frequency (Fs)30.3 Hz
DC Resistance (Re)6.41 ohms
Voice Coil Inductance (Le)2.32 mH
Mechanical Q (Qms)3.06
Electromagnetic Q (Qes)0.49
Total Q (Qts)0.42
Compliance Equivalent Volume (Vas) 1.61 ft.³
Mechanical Compliance of Suspension (Cms)0.77 mm/N
BL Product (BL)9.5 TmDiaphragm Mass Inc. Airload (Mms)36.1g
Maximum Linear Excursion (Xmax)4.5 mmSurface Area of Cone (Sd)211.2 cm²
For the volume of the existing box 0.4 ft^3 I would get a QTC of 0.93 with this woofer. Quite a bit higher than I wanted, but perhaps stuffing it with half a pound of polyfil will lower the QTC into an acceptable range to use this for low to mid volume music? I don't expect much out of this, it's just kind of fun for me to imagine a modded system that will sound as good as the original or perhaps even better. I do prefer sealed over ported usually and so this route seemed like a good idea, esp if the woofer is now a step up in size/quality than the original. I'm just hesitant to throw in this 8 in this sealed box with a QTC that high. I guess I would have to hear it to truly know if I like it, right?
I won't be surprised if the output from the subwoofer amplifier is EQ'd a bit to get the best results out of the original driver in that small of a box. So just replacing the driver based on t/s parameters alone would be a bit of crap shoot. I'd actually be tempted to go with a driver with a bit more Xmax, like the DSA175.
But just to confirm a few things, what is the estimated internal (net) volume of the box, and what diameter and length is the vent?
But just to confirm a few things, what is the estimated internal (net) volume of the box, and what diameter and length is the vent?
Estimated internal volume is 0.39 ft^3. I can't seem to find the specs for the port length. The port curves after a few inches and continues for several more inches. Would a measurement of the length of that entire peace, curves and all, be the port length?
I am open to an 8 that can be sealed and work for that internal volume (with polyfil of course). Otherwise I'll just get that other 6.5 and pop it on. I know it won't be that loud, or exciting, but I don't want to throw the thing away. I do enjoy the satellites and the old subwoofer seemed ok. I might even give it away to someone that i know would enjoy it since I have a better set of speakers/subwoofer for my personal music listening.
I am open to an 8 that can be sealed and work for that internal volume (with polyfil of course). Otherwise I'll just get that other 6.5 and pop it on. I know it won't be that loud, or exciting, but I don't want to throw the thing away. I do enjoy the satellites and the old subwoofer seemed ok. I might even give it away to someone that i know would enjoy it since I have a better set of speakers/subwoofer for my personal music listening.
realistically you will not match the performance of the stock "sub" in the factory enclosure without replacing it with a decent excursion driver while maintaining the ported orientation. if your plan is to go sealed, even with more displacement, scrap the thing in it's entirety and go for something from scratch.
Brian is correct in that there is likely an eq built into the amp outputs. so regardless of your preference of sealed vs ported, the sound is tailored. the work around being a TL system, but thats still a long shot.
Brian is correct in that there is likely an eq built into the amp outputs. so regardless of your preference of sealed vs ported, the sound is tailored. the work around being a TL system, but thats still a long shot.
Yep. If I was undertaking a project like this, the first thing I would be doing would be measuring that amp's voltage output at different frequencies and different output levels. Given the description of the box and the port length, I won't be surprised if this is some sort of "B6" alignment, where Fb is low and a boost is applied @ Fb, the intent being to obtain a lower cutoff point in a smaller box size.
Thanks everybody for the replies, they were useful for me to assess whether it was worth it for me to spend the time/money on a suitable replacement woofer/subwoofer. I have decided that it isn't really worth it to put any money into this, given that I have a lot of better gear lying around. I gave the entire 2.1 to a friend and told him all this info from all of you. He's going to throw in the Dayton Audio DC160-8 6-1/2" Classic Woofer and leave the port intact, and call it a day.
This is a great forum, and I'll surely make use of it in the future, and of course when I reach a level of competence with DIY audio, I'll give it back in kind. Cheers!
This is a great forum, and I'll surely make use of it in the future, and of course when I reach a level of competence with DIY audio, I'll give it back in kind. Cheers!
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