| Dave Jones |
I'm thinking about slapping a Peerless 830500 into a pre-fab box and calling it my subwoofer. It will be used with a fairly low crossover point. Plus, I'm sort of fixated on the idea of a Qtc of 0.5. Don't ask me why. I'll be using it in conjunction with a pair of Lynn Olson Ariels in a moderate size living room. I won't be playing it at volumes that will make the neighbors call the police. Is the Peerless the best choice?
The published T/S parameter Qts=0.2 along with Qtc=0.5 yields a closed box size of .94 cubic feet (26.5L).
Given that (unlike you all) I am only a borderline genius, and I don't know what I'm doing, a whole bunch of questions come to mind.
Are there pre-fab boxes available in sizes other that 1, 2, and 3 cubic feet?
About how much volume does a 12" woofer displace? (For that matter, how about other sizes?)
I've read that stuffing can increase apparent box volume "by 25%." Does that mean to figure the unstuffed box at 4/5 the size you want? If so, what kind of stuffing and what density?
Is there room in a 1 cu ft box for a plate amp? For example, look at this one:
http://www.partsexpress.com/pe/show...t_ID=9388&DID=7
If I figgered right, it displaces .157 cu ft (4.43L). Using the Peerless, my target volume is .94*(4/5) = .752 cu ft (21.2L), which would leave .09 cu ft (2.55L) for the woofer. It looks as though the plate amp and woofer might both fit in the 1 cu ft box. Yes? No?
Finally, what kind of amp to use? I have a Richter Scale Series III [ http://www.audiocontrol.com/homeaudio.htm ], so I could use that with an external mono amp. Or I could use a plate amp, perhaps with some built-in EQ. Or I could use the Richter Scale for EQ only in conjunction wity a plate amp. If I get a plate amp, should I get one with a 6 dB boost at 30hz, or a flat one? Or should I spring for the expensive "500 Watt" amp (273 Watt -> 8 ohm) at Parts Express with its cool features?
http://www.partsexpress.com/pe/show...ID=124777&DID=7
Would it displace too much volume?
Other plate amps? How about an external mono amp? -- Any suggestions for a brand/model?
Finally, finally, if you were wanted a super clean and tight subwoofer to go with a pair of Lynn Olson Ariel speakers, what would you do?
Whew! |
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| Timn8ter |
| How about this one. It impressed a lot of people at T.H.E. Show. You can almost see it in this picture behind the left speakers. |
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| Dave Jones |
| I can now answer one of my questions. I found a spec for the Shiva 12" saying it displaces 3L (.106 cu ft). Supposedly, other typical 12-inchers would measure similarly. |
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| mikee12345 |
To move air is one thing
To move air LINEARLY is another!
=for 20hz ish = multiples of shiva/dpl12 etc..It simply wouldnt satisfy my mind knowing they are moving at 14mm excursion(oneway) regularly.
Id then measure the Sinewave quality and cosine shaped sine bursts...and transient response 'blips'
| quote: | | Plus, I'm sort of fixated on the idea of a Qtc of 0.5. Don't ask me why |
i wont ask why,because i know Qtc=0.5 is good. The problem is\how different does it sound from Qtc=0.707,and what box volume does it require.
| quote: | | Finally, finally, if you were wanted a super clean and tight subwoofer to go with a pair of Lynn Olson Ariel speakers, what would you do? |
basshorn. Or other expensive quality transducer....or multiples of cheaper ones
:) |
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| SY |
Given the realities of room gain, a 0.5 Qtc isn't a bad idea, especially if the driver is coupled closely to the floor. I haven't personally tried the Shiva, but heard good things. I'm VERY pleased with the closed box I built for a buddy of mine, using an NHT 1259, mounted near the floor, with a Qtc about what you're aiming at. We used separate subs for each channel. You won't get insane SPLs from it, but it plays plenty loud (as loud as the near-SOTA-NHT3.3s).
For an amp, forget the frills and features (you can build them into the crossover- you ARE using an electronic crossover, right?). You just want POWER. |
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| chrish |
I am also looking at building some sub-woofers to go with my newly constructed ariels. Have you seen this page, http://www.nutshellhifi.com/ME2txt.html#me2
This is what Lynn Olson recommends to accompany his ariels and is what I am probably going to build.
Good luck.
Chris |
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| Dave Jones |
| quote: | Originally posted by chrish
I am also looking at building some sub-woofers to go with my newly constructed ariels. Have you seen this page, http://www.nutshellhifi.com/ME2txt.html#me2
This is what Lynn Olson recommends to accompany his ariels and is what I am probably going to build.
Good luck.
Chris |
Yes, I've seen that. I hope not to use that many drivers. I don't need enormous amounts of SPL. |
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| Dave Jones |
| quote: | Originally posted by SY
Given the realities of room gain, a 0.5 Qtc isn't a bad idea, especially if the driver is coupled closely to the floor. I haven't personally tried the Shiva, but heard good things. I'm VERY pleased with the closed box I built for a buddy of mine, using an NHT 1259, mounted near the floor, with a Qtc about what you're aiming at. We used separate subs for each channel. You won't get insane SPLs from it, but it plays plenty loud (as loud as the near-SOTA-NHT3.3s).
For an amp, forget the frills and features (you can build them into the crossover- you ARE using an electronic crossover, right?). You just want POWER. |
The NHT 1259 has a published Qts of 0.445. How big is the box you built?
In answer to your questions, yes, I will use an electronic crossover. I might use a Richter Scale III that I have, or I might use a plate amp. |
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| SY |
| I'll check the volume when I get home. It was pretty big, hitting a Q = 0.577 target once it was stuffed. More like an infinite baffle than acoustic suspension, that's for sure. |
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| Dave Jones |
Here's another idea.
How about a Shiva Mark III in a 3 cu ft box? That would be real close to Qts=0.5 with minimal stuffing. The makers say 3 cu foot with 32 oz of polyfill has an in-room F3 of 27Hz. They also list a ported 3 cu ft alignment with an in-room F3 of 23Hz. I could build it with a port fitted with a removeable cover. The only question would be how much stuffing to put in the thing.
I've got space in the living room for a 3 cu ft box, so I think this is a better idea than trying to jam the Peerless into a 1 cu ft box. |
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| Dave Jones |
| quote: | Originally posted by Dave Jones
Yes, I've seen that. I hope not to use that many drivers. I don't need enormous amounts of SPL. |
Following up on my answer (too late to edit)...
The only thing that gives me pause is this quote from Lynn Olson:
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The second reason? Most well-reviewed "audiophile" drivers have magnetic circuits that are no better than consumer-grade; it just isn't a priority, since hi-fi magazines don't care much about IM distortion in speakers. In the real world, though, IM distortion is a very important consideration. Few bass drivers have magnet systems optimized for low IM distortion; the only ones I know of are expensive professional studio monitor drivers from JBL, Altec, and TAD, and the Scan-Speak drivers for consumer use. |
That was written a few years ago. Perhaps the situation has improved. I wonder if the drivers I am considering have low IM distortion figures. Anyone know? |
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| Dave Jones |
| quote: | Originally posted by Dave Jones
Here's another idea.
How about a Shiva Mark III in a 3 cu ft box? That would be real close to Qts=0.5 with minimal stuffing. The makers say 3 cu foot with 32 oz of polyfill has an in-room F3 of 27Hz. They also list a ported 3 cu ft alignment with an in-room F3 of 23Hz. I could build it with a port fitted with a removeable cover. The only question would be how much stuffing to put in the thing.
I've got space in the living room for a 3 cu ft box, so I think this is a better idea than trying to jam the Peerless into a 1 cu ft box. |
Dang it! I made a math error. I forgot to subtract a 1. A Shiva in a 3 cu ft box will not be right at Q=0.5. ... and it's too late to edit or delete the post. Sorry. |
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| 454Casull |
Why not use an AA Tempest? It's only $25 more and goes lower louder.
Also, you can put the plate amp on the outside of the enclosure. |
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| Dave Jones |
| quote: | Originally posted by 454Casull
Why not use an AA Tempest? |
... because I want a Q of around 0.5. In a 3 cu ft box, the Tempest would have a Q of 0.84.
There just don't seem to be any low Q woofers other than the Peerless and some 8 and 10 inchers from Scan Speak. If someone knows of others, please speak up. |
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| 454Casull |
| Really that averse to building your own box? |
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| SY |
Dave: The 1259 sub I mentioned ran about 8 cu ft.
I'd like to try that driver in a TL. |
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| kelticwizard |
Dave:
Well, if you want to get creative, two TangBand 8" subs put into a 26 liter enclosure, (26 liters for the both together), will yield a Qtc of 0.5 and and an Fc of 46 Hz, assuming the published Thiele-Small numbers hold up.
That is less than 1 cu ft.
http://www.tb-speaker.com/detail/woofer/w8-740c.asp
You can use the money you save by buying these to purchase another plate amp to drive the second woofer, since these both are 4 ohms and plate amps work best into 4 ohms. The second plate amp will boost the sensitivity up to 90 dB as well.
Take a 1.5 cu ft enclosure which i believe is available, hook the two amps up and put bricks into it to make up the extra space.
I don't know if an Fc of 47 Hz is what you want, though. |
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| catapult |
I'd go for the Peerless in a sealed 2 cu.ft. box. That's only a little bigger than the 50 liters Siegfried Linkwitz used in his Thor sub and a plate amp would take up most of that. Sealed subs are pretty insensitive to minor changes in box volume and room effects have a much greater impact on the frequency response.
http://web.archive.org/web/20030606.../thor-intro.htm
Edit: or, if one is available, a stuffed 1.5 cu.ft. box should be fine. Maybe even better. SL doesn't like stuffing but I do. It will eliminate the 300Hz null he gets due to box dimensions. I'd even stuff a 2 cu.ft. box and use EQ to adjust the frequency response. |
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