Hi!
I have been searching for some design ideas for the Hi-Fi version of the Dayton RS 12" sub, especially since they are sale this month, but I have yet to find any that have caught my eye. Thus, I figured I would throw something out there for comments before diving into building a new sub. This is my first attempt at designing a speaker, so any comments are more than welcome!
Here are my design goals:
“Moderate” box size
Sealed box
Usable response down to 20 Hz
Cheap!!!
I want to use a sealed box, both for ease of construction and to avoid port issues/noise. Of course, a good starting point would be to model the response of the speaker in the box, so I used WinISD and got the response below in a 1.9 cu. ft. sealed box. Obviously there is a lot missing on the low end. To solve this, I would like to use a Linkwitz transform circuit as an EQ to bring up the low end. Modeling this circuit to try and get f3 of 20 Hz gives, what I believe to be, pretty reasonable values without too drastically having to boost the low end. (If the circuit/component values would be helpful, I’ll post them too!) I know the ~8dB boost at 20Hz is a lot to ask of the amp, but as I said, I am not looking for massive output in that frequency range—just something reasonable.
I figured a Bash 300W plate amp would be a nice fit for this since I am not trying to tear the house down with this sub. Also, I would be worried about too much power for this driver if I went with a 500W amp. If I do need more output, I can add another unit, but I am not really a volume fiend (not that that is bad or any thing!) so I doubt that I will ever push this unit to its max. (Famous last words, right??)
If anyone has comments as to the viability of this design or comments about using Linkwitz transform circuits, I would love to hear them!
Thanks!
David
I have been searching for some design ideas for the Hi-Fi version of the Dayton RS 12" sub, especially since they are sale this month, but I have yet to find any that have caught my eye. Thus, I figured I would throw something out there for comments before diving into building a new sub. This is my first attempt at designing a speaker, so any comments are more than welcome!
Here are my design goals:
“Moderate” box size
Sealed box
Usable response down to 20 Hz
Cheap!!!
I want to use a sealed box, both for ease of construction and to avoid port issues/noise. Of course, a good starting point would be to model the response of the speaker in the box, so I used WinISD and got the response below in a 1.9 cu. ft. sealed box. Obviously there is a lot missing on the low end. To solve this, I would like to use a Linkwitz transform circuit as an EQ to bring up the low end. Modeling this circuit to try and get f3 of 20 Hz gives, what I believe to be, pretty reasonable values without too drastically having to boost the low end. (If the circuit/component values would be helpful, I’ll post them too!) I know the ~8dB boost at 20Hz is a lot to ask of the amp, but as I said, I am not looking for massive output in that frequency range—just something reasonable.
I figured a Bash 300W plate amp would be a nice fit for this since I am not trying to tear the house down with this sub. Also, I would be worried about too much power for this driver if I went with a 500W amp. If I do need more output, I can add another unit, but I am not really a volume fiend (not that that is bad or any thing!) so I doubt that I will ever push this unit to its max. (Famous last words, right??)
If anyone has comments as to the viability of this design or comments about using Linkwitz transform circuits, I would love to hear them!
Thanks!
David
I would suggest not to linkwitz transform it down to 20 hz, 30hz is a more reasonable target in my opinion for the sealed subwoofer. I have solely a rumble filter at 16hz, and the cone looks like it is excursing about as far as it should at respectable listening levels, I wouldn't want it to go further.
Also, try playing with the sub and test tones once you build it. I can't hear anything below 30 hz even though I'm sure there is output (spl meter, plus parts of house resonate). I would like to hear other's thoughts on this.
I believe linkwitz discusses somewhere on his site the pros and cons of his transform with respect to excursion limits. Look at his thor subwoofer, it is very similar in my opinion to a sealed dayton rf.
Another issue, factor in the lowpass to the sub into the winisd model. It looks more like an upside down parabola, and the -3db point relative to the peak spl output from the sub will be lower in frequency.
Also, try playing with the sub and test tones once you build it. I can't hear anything below 30 hz even though I'm sure there is output (spl meter, plus parts of house resonate). I would like to hear other's thoughts on this.
I believe linkwitz discusses somewhere on his site the pros and cons of his transform with respect to excursion limits. Look at his thor subwoofer, it is very similar in my opinion to a sealed dayton rf.
Another issue, factor in the lowpass to the sub into the winisd model. It looks more like an upside down parabola, and the -3db point relative to the peak spl output from the sub will be lower in frequency.
I have indeed looked at Linkwitz's web page, and his Thor sub based on the Peerless XLS 12" was what gave me the idea for this design. He uses a more complicated crossover topology for the Thor than what I am interested in, but he also takes the boost out well past 20 Hz. That may very well be driver dependent, so I will definitely heed your suggestions about the excursion limits of this driver and play with the LT circuit before making anything permanent.
From your comments it sounds like you have one of these drivers already--is this accurate? I would like some feedback (positive or negative) about this sub since so few opinions exist from people who have actually used this driver.
As for your question regarding hearing below 30 Hz, I think I can hear down to ~20, though below 25 it is primarily feel with a little reinforcement with the ears, if that makes any sense. For me there is definitely a steep roll-off below 25, though I am not confident that I have ever really heard a system capable of producing high SPL low frequencies that would let me claim this 100% yet. Anyway, I would love to have down to 20 Hz just to have all of my bases covered (though I am still a LONG way away from considering one of those fan subs to get down to 1Hz!)
From your comments it sounds like you have one of these drivers already--is this accurate? I would like some feedback (positive or negative) about this sub since so few opinions exist from people who have actually used this driver.
As for your question regarding hearing below 30 Hz, I think I can hear down to ~20, though below 25 it is primarily feel with a little reinforcement with the ears, if that makes any sense. For me there is definitely a steep roll-off below 25, though I am not confident that I have ever really heard a system capable of producing high SPL low frequencies that would let me claim this 100% yet. Anyway, I would love to have down to 20 Hz just to have all of my bases covered (though I am still a LONG way away from considering one of those fan subs to get down to 1Hz!)
Yes, I have 2 x sealed subwoofers with 2.2 cubic feet and the dayton hf 12". I definitely don't think they are holding my system back (stereo martin logan mosaics to be replaced with diys). I'd say they are clean, but that will depend on how you design the sub crossover, I think Linkwitz transforms are good for group delay. The way I have them crossed now (just a rumble filter), they make movies fun but don't quite rattle the house.
I can't give any critical audiophile comments as I don't have golden ears, and they are not crossed over correctly into my mains because they will be moved shortly(should be 24db/oct).
If you want, I can post a measurement for 25 hz spl, just tell me, but I got to go to class now.
I can't give any critical audiophile comments as I don't have golden ears, and they are not crossed over correctly into my mains because they will be moved shortly(should be 24db/oct).
If you want, I can post a measurement for 25 hz spl, just tell me, but I got to go to class now.
I was watching the cone, and playing a 25 hz test tone. From watching some white dot on the cone moving back and forth, it looked like about 12 mm peak to peak excursion resulted in 90 dB at 1 meter using an uncalibrated radioshack digital meter (+5db if same calibration as analog). I stopped there because my house was going to explode, and my subwoofer is my baby and I don't want to hurt it.
I think it would get about 6db more at full excursion according to winisd.
I think it would get about 6db more at full excursion according to winisd.
Nice!! Thanks for the measurement.mazurek said:
As another EQ option I have been looking at the built in bass boost of the Bash amp. Taking room gain into consideration (thanks owdi! though I am not sure I am doing it right yet. . . .), enabling a +5 db boost at 20-24 Hz smooths out the low end fairly nicely. Of course, without room gain, the bass boost doesn't do enough--thus the original proposal for using a LT. There is a little peaking, so I am sure I am going to have to play with the system to get it right once it is in the room, but eliminating the LT would definitely simplify things.
Something else to try is WinISD .50a7 (the alpha version). This is much more powerful than the pro version, and can show you maximum SPL and power graphs.
In a 1.9 cu ft. box, the Dayton 12" HF sub can hit 100db at 25hz w/ 250 watts at full xmax.
I tried a few different configurations and the amount of bass boost you will want really depends on the in room response. 5db at 25-30 hz seems right in a midsize room.
A ported box would be much more difficult given your size restrictions. The only way you could pull it off is by doubling box size, using a slot port, and half the box would be the port.
Dan
In a 1.9 cu ft. box, the Dayton 12" HF sub can hit 100db at 25hz w/ 250 watts at full xmax.
I tried a few different configurations and the amount of bass boost you will want really depends on the in room response. 5db at 25-30 hz seems right in a midsize room.
A ported box would be much more difficult given your size restrictions. The only way you could pull it off is by doubling box size, using a slot port, and half the box would be the port.
Dan
I actually switched to that in hopes of finding the room response function, but all I could manage was using a LT to simulate room gain.owdi said:
That's what I was using to model the amp bass boost, and assuming a 3-6 db room gain at 20 Hz, the +5 bass boost at 22 Hz gave me a little better low end extension than the 25-30. Of course I am sure we are using different paramaters somewhere to cause the discrepency, but either way, I am sure that you will agree that playing around with it once the sub is in the room will be the ultimate guide! (I am sure my wife will love to hear that!)
Absolutely! And I have never heard a ported box that I like. I am CERTAIN that they exist, but I have yet to find it. I am pretty comfortable with the 2.1 cu ft sealed box coupled with electronic EQ to get down to the range I want. If it sounds terrible, I can always try another one!owdi said:
Well, I just finished hooking it up (figured priming the box without putting on a slick finish would be sufficient since it would be hidden most of the time), and I am quite impressed if I do say so myself.
I have not been able to run frequency sweeps due to my wife wanting to watch Charlie and the Chocolate Factory, but so far the sound sems pretty ballanced and definitely fills out my North Creek CM-77's well.
Final configuration was 2.1 cu. ft. box with +4db @ 22 Hz. I unfortunately don't have a mic. that is anywhere close to flat (that is definitely on my wish list, though!), so I can't post response curves in the room. I will, however, let you know qualitativetely what is going on when I get a chance.
Thanks everyone for the feedback!
I have not been able to run frequency sweeps due to my wife wanting to watch Charlie and the Chocolate Factory
, but so far the sound sems pretty ballanced and definitely fills out my North Creek CM-77's well. Final configuration was 2.1 cu. ft. box with +4db @ 22 Hz. I unfortunately don't have a mic. that is anywhere close to flat (that is definitely on my wish list, though!), so I can't post response curves in the room. I will, however, let you know qualitativetely what is going on when I get a chance.
Thanks everyone for the feedback!
I just completed a project with the BASH 300W amp and I really like it (different driver though). To enable me to easily adjust the boost I added a temporary bread board for the boost resistors and ran it outside of the enclosure during testing. This worked well but introduced a bit of hum that went away as soon as the final resistors were soldered to the amp's boards.
I used WinISD to model the system. In my listening room (23 ft. by 13 ft by 7 ft - in the basement) the bass gain fit a parametric EQ setting of 23 Hz, +3dB, with Q=0.65. I'm sure other rooms are quite different, but that may be a starting point to help you to determine how much EQ boost you will need in your design. With those figures WinISD was spot-on with the in-room response of the system. I was quite pleasantly surprised.
-Troy
I used WinISD to model the system. In my listening room (23 ft. by 13 ft by 7 ft - in the basement) the bass gain fit a parametric EQ setting of 23 Hz, +3dB, with Q=0.65. I'm sure other rooms are quite different, but that may be a starting point to help you to determine how much EQ boost you will need in your design. With those figures WinISD was spot-on with the in-room response of the system. I was quite pleasantly surprised.
-Troy
I have also been pleasantly surprised. WinISD seems to have hit the parameters spot on. The sub qualitatively has a pretty flat response from ~100 Hz to 30 Hz based on my ears not noticing any nasty peaks or dips in response while running sine wave sweeps. Below that, I start loosing hearing sensitivity, so I can’t make a good judgment as to intensity, though there is definitely usable response down to ~22 Hz which is where I can’t hear it any more, but the cone is still definitely cranking below that. Fortunately, there don’t seem to be any nasty room mode peaks and the rough room modeling seems to be spot on.
I must admit that I am not one to believe in vanishingly low ripple in frequency response curves. As long as I don’t notice peaks, they don’t exist to me! That being said, I can happily say that this sub is “Flat to Me.” (insert catch phrase trademark symbol here! ). I was worried this would not be the case due to using the bass boost on the amp, but it seems to blend quite well. This was definitely easier than using a LT circuit.
EDIT: forgot to mention that I posted a cutout sheet for the box in another thread in case anyone is interested. The thread is here: http://www.diyaudio.com/forums/showthread.php?s=&threadid=71667
I must admit that I am not one to believe in vanishingly low ripple in frequency response curves. As long as I don’t notice peaks, they don’t exist to me!
That being said, I can happily say that this sub is “Flat to Me.” (insert catch phrase trademark symbol here! ). I was worried this would not be the case due to using the bass boost on the amp, but it seems to blend quite well. This was definitely easier than using a LT circuit.EDIT: forgot to mention that I posted a cutout sheet for the box in another thread in case anyone is interested. The thread is here: http://www.diyaudio.com/forums/showthread.php?s=&threadid=71667
- Status
- This old topic is closed. If you want to reopen this topic, contact a moderator using the "Report Post" button.