I'm finally able to build a new sub and I think I've got a pretty good idea of what I'm going to do. Like the title says, I'm using the Dayton RSHF 10" sub with the BASH 300W plate amp. Using WinISD I'm planning on a 2-2.5 cubic ft box tuned somewhere in the 20s. The problem I'm seeing is that the is a ~3db peak that starts at 40htz and peaks at 30htz and drops off rapidly after that. I don't want to go bigger than 2.5 cubic ft if I can but I can't seem to get a flat response. What do you suggest I do to knock that peak down? Can I modify the bass boost on the BASH to compensate? Also, I plan on using the precision 4" port.
I'm shooting for building this weekend if I can get a design I'm comfortable with.
I believe the response peak is coming from the size of the box, a bit large for your tuning point-lower the tune below 20hz and the peak goes with it but then your port length is excessive. You need a compromise. 2.2 cubes net or 60L tuned to 22hz gives the flattest response with a 4" port (the minimum diameter you can use here) at 30 inches long with a slight resonance at 214hz or so. It's out of the passband so don't worry about it. A tall box will work with a downfiring driver and port for summed output would work nicely. Would make a nice MT bookshelf stand as well. The flat response may not be the best for your room though. If you know or measure your room mode, you may find that you want a bit of rolloff beginning before the mode since their isn't any peQ on the Bash amp. Either way you will need a filter below tune to keep the driver from bottoming out. I'm not sure what the Bash amp does but the PE240 rolls off nicely around 25hz, protecting the driver as well. Hope this helps
I believe the response peak is coming from the size of the box, a bit large for your tuning point-lower the tune below 20hz and the peak goes with it but then your port length is excessive. You need a compromise. 2.2 cubes net or 60L tuned to 22hz gives the flattest response with a 4" port (the minimum diameter you can use here) at 30 inches long with a slight resonance at 214hz or so. It's out of the passband so don't worry about it. A tall box will work with a downfiring driver and port for summed output would work nicely. Would make a nice MT bookshelf stand as well. The flat response may not be the best for your room though. If you know or measure your room mode, you may find that you want a bit of rolloff beginning before the mode since their isn't any peQ on the Bash amp. Either way you will need a filter below tune to keep the driver from bottoming out. I'm not sure what the Bash amp does but the PE240 rolls off nicely around 25hz, protecting the driver as well. Hope this helps
I don't really see the problem you're talkin' about.
Using old (last year - in catalog) and new (Dayton Audio PDFs) T/S parms, averaged (don't know if I trust the new DA data as yet), that's Qe=.48, Qm=3.03, Qts=.41, Vas=1.84, Fs=24
WinISD Pro Alpha looks good in a 2 cf box, with a 4"d x 28" port, Fb=23, F3=22, basically NO peak, not counting any boost the BASH might have. I've thought about this before, even in a tall 3-way (like the "Titan" in SB201) with a port firing out the bottom or top.
There COULD be a bit of a "rise", but most "subs" don't really have any "flat" range anyhoo, AAMOF, going upfreq., they typically never reach their spec'd SPL, since they're being rolled off way befor e they reach it. My Q12/240w sub is set to LP as low as it can go, 50 Hz I think.
I was using the specs provided by PE on the webpage. I bought a 4" precision port that has a max length of 17". With a 2.2cf box that makes it tuned to 27htz. It will only go flat when I tune it to FS for the driver which is 22htz. That nearly doubles the port length though.
I was using the specs provided by PE on the webpage. I bought a 4" precision port that has a max length of 17". With a 2.2cf box that makes it tuned to 27htz. It will only go flat when I tune it to FS for the driver which is 22htz. That nearly doubles the port length though.
OK, that makes more sense... the previous info was too vague, thus the varying responses. The 27 Hz tuned graph isn't terrible, but I would much rather not have the 3 dB bump.
That's the trade-off, no way around it... long port and flat response, or shorter port and a response peak... the choice is yours.
I would build a bigger box, say three cubic feet or so. Then the port will tune to a lower frequency and likely flattening the response down low.
But if you're going to build a bigger box anyways, why not just shoot for optimum airspace and get the port length that you really need. Going with an oversized enclosure just to keep port length the same seems like a step in the wrong direction.
What is the the theory behind this? I don't know much about crossover theory although I have gone over it a little in analog circuit class 6 years ago. Are you suggesting 4 to run in parallel to achieve a 400 w capability?
To all-
I built the cabinet this weekend. I ended going to approximately 2.5 cf with 17" x 4" port which tunes it to 25hz. Now I have tested it in my room and the response curve winISD calculated is pretty much what it does. It has impressive low end but it over power my mains. Now the problem is I ran a quick test with Room EQ Wizard and I'm getting a huge dip in the 50hz range which I can tell when I play music and some other things. When I turn the sub off my main seem louder and that signal so I'm guessing I'm getting some cancellation. Reversing the phase makes is worse. What do you suggest I do to alleviate the problem, or can I?
-Any other suggestion for an alignment for this particular sub? The cabinet is not finished, lightly sanded and 1 coat of primer. I'm not afraid to rebuild the cabinet to make the most out of this driver.
Your right about the mains. The crossover was set at 60hz via the receiver. Just to note the main are very cheap KLHs I bought on several years ago. I'm looking to build new within the next 6 months and I want a well integrated system which is why I want to get the sub good enough to match better speakers.
You could set the Xo on the receiver higher until you get better mains-the KLH's roll off too soon for your XO point. 80hz is usually a good match, as it should get rid of that dip in your freq response. Also the slope of your receiver is really steep-what receiver/preamp do you have?
try setting the mains at 80hz . it could be that your receiver may have a bad crossover. it may send 60hz up to the mains and 45 hz down to the sub.
the idea of the caps is a highpass filter at 25hz. 4 caps of 500uf in parallel are 2000uf same voltage the highpass shifts the curve. the bump you modeled will occur but moved to 100 or 110 hz out of the sub range. The sub you built does not really sound as good below 25hz as it will sound between 25hz and 80hz or 100hz. when you get past its tuning point it distorts more.
As to having a sub that overpowers its sats. shifting up to 80hz or 100hz will take the load off the sats . they don't really want to play to 60hz.
I have played around with building a long time. some subs go to 30hz great under that no go. and computer models are not perfect they get you in the ballpark. that is a nice sub. but under 25hz not so nice If I had it I would limit it to 30hz for the low. I would add a second identical one and use the two as stands for my mains. then down the road think of a sub to run 18hz to 40 hz. look at my dayton rss390hf-4 IB click on my name and then click public profile then look to the right and click on my album. the IB crosses to a pair of nht1259's great sealed subs from 35hz to 100hz. not too good under 35hz. so I run the 1259's from 50hz to 100hz the dayton rss390 from 18hz to 50hz the sats are focal 7w mtm's great from 70hz to 20000hz. so I really have 1 sub sub 18hz to 50hz 2 subs 50hz to 100hz and 5 sats 100hz to 20000hz. all of the speakers have head room. the f3 on the sats is 50hz they cross at 100hz makes it easy on them the f3 on the ht1259 is 32hz they cross at 50hz makes it east on them the f3 on the dayton is 18hz I let it go there, but most soundtracks don't get that low. what is good about it is you can add a piece at a time. to get the right system
Last edited by philiparcario; 07-08-2008 at 09:40 AM.
Reason: more info
Hey Phil-how do you like the MCM monitor amps-i'm concerned that they won't have enough headroom for a fairly large HT-26x18x10 5.3. Also, how do you cross your mains-external active xo or speaker level sub in/outs?
Hey Phil-how do you like the MCM monitor amps-i'm concerned that they won't have enough headroom for a fairly large HT-26x18x10 5.3. Also, how do you cross your mains ?
I love the monitors but my speakers are really sensitive. the woofers are 88db in parallel which is 94db without bsc and the tweeter is 95db. they can handle 150 watts. the audio refinement amps had 125 at 8ohms and 200 at 4 ohms. i could not turn the volume past 2 or 3 of 10. it was just too loud my home theater is 10 by 22 by 7.5. but I watch the short way 10 feet and use a corner of the den so it is really 10 by 14 by 7.5 with a huge opening on the viewers left. headroom is not an issue. your room is bigger the speakers you drive may not be sensitive enough.
I use a technics 500 processsor wolf mentioned it. used on ebay . i got a really good price 105 shipped. here are two links from sellers right now
Dayton RSHF and Bash 300 Sub Project
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Originally Posted by Mayhem13
