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Discussion Starter #1 (Edited)
**EDIT** 10/25/11... I ENDED UP BUILDING WITH (2) FI18'S, YOU CAN FOLLOW THAT THREAD (Glenn's IB sub, (2)FI18's) HERE... http://www.hometheatershack.com/forums/ib-infinite-baffle-subwoofer-build-projects/50657-glenns-ib-sub-2-fi18s.html


If I can find affordably good sounding sub drivers, I've decided to do an IB manifold. I want to do 4-15" drivers in the attic.
Trying to keep the price of each sub below $200.
***I value sound quality over SPL's.*** I want to be able to hear the difference between an electric bass guitar, an accoustic bass guitar, and an upright bass. I want to hear the difference between a tympani (sp?) and a bass drum.
I like the sound quality that comes from my sealed 15" Tempest and HSU VTF subs.
1)..Do the Dayton IB385-8 15" drivers have decent sound quality?
2)..Is there a different driver under $200 that would be preferable?
3)..Should I not waste my time with these cheaper drivers? I understand the new Fi IB3's would be better, but they are much pricier.
 

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Elite Shackster
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Looking purely at is parameters it looks a decent driver for IB use. I couldnt comment on its sound quality, but its Qts is pretty good, power handling looks about what I would expect, FS is nice and low and although the xmax isnt as high as the best drivers, using multiples will reduce excursion requirements.

You really need to model the driver to see how many your going to need though. Also, what size room do you for the 'enclosure', do you know its volume?

Taking the typical minimum IB requirement of 4 drivers for 15 " drivers, you would only need 200 watts and you would good to about 100db at 10hz. Using a HPF you can get more spl, but if you want more spl at 10 hz you will need more drivers to stay within xmax.
 

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Discussion Starter #5
Thank you, I always value your input.
... Also, what size room do you for the 'enclosure', do you know its volume?...
Mostly typical attic that is 44'x28', the area of the great room does have a cathedral ceiling which would reduce the attic size a bit, but I figure it's still plenty of space for whatever I need.

I'm not a bass hog, just want it to sound proper. 2-15"er's would probably put out enough SPL for me but I don't want distortion, so that's why I figured to use 4 (I've already read that IB drivers can bottom out easier than when in typical smaller enclosures ("Hear the bass, not the box!!").
 

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Elite Shackster
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I modelled it yesterday and the 4 drivers IIRC needed about 12,500 litres to achieve the 10 times vas enclosure size. You can get away with as little as 4 times vas though (around 4000 litres) so you will likely be fine no matter what. The beauty of IB's is that big differences in enclosure size dont have that big an effect on the eventual sound, and higher Q installs are much more acceptable due to the clean output nature of IB's.

I look forward to a build thread :T
 

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Elite Shackster
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:bigsmile: we do like to see subs being built. An IB install would be of particular value as they are the rarest of builds due to their unique install requirements.

In any case, I hope the end results please you, and that if nothing else you can share your thoughts on how you think your IB performs. Ive not seen these drivers used before either, so that further peaks my interest.
 

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Discussion Starter #9
I'll try not to forget the obligatory pic with the head in the hole. I've gained a few pounds over the years, we'll see if my head can fit through.
 

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If I can find affordably good sounding sub drivers, I've decided to do an IB manifold. I want to do 4-15" drivers in the attic.
Trying to keep the price of each sub below $200.
***I value sound quality over SPL's.*** I want to be able to hear the difference between an electric bass guitar, an accoustic bass guitar, and an upright bass. I want to hear the difference between a tympani (sp?) and a bass drum.
I like the sound quality that comes from my sealed 15" Tempest and HSU VTF subs.
1)..Do the Dayton IB385-8 15" drivers have decent sound quality?
2)..Is there a different driver under $200 that would be preferable?
3)..Should I not waste my time with these cheaper drivers? I understand the new Fi IB3's would be better, but they are much pricier.
Driver selection for IB use is extremely limited. Supposedly, due to the nature or design of IB, it shouldn't require advanced features eg copper rings, so you should be fine. I've been curious which would sound better between four Dayton IB385 drivers or two dual IB18 drivers if in one manifold. I wonder about the performance between two 2x15" manifolds vs one 2x18".

Will you be building a pair of opposed manifolds or one quad manifold? I'm guessing dual manifolds can smooth response, same as other designs, although dual manifolds will require twice the work...and you stated sound quality was of utmost importance.
 

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Elite Shackster
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2 x 18 will generally be equal to 2 x 15 between drivers from the same range. The difference is usually in the Vas of the drivers, meaning different space requirements, and typically from what I have seen 2 x 15 will still work in a smaller cab that 2 x 18. As ever, same results from smaller cab drives up cost. Where the 4 x 15 will excel is in power handling, as the system can take twice the power giving theoretically more max spl, dependant on the frequency you want to drop to.

Personally, I would go 4x15 in a pair of dual opposed manifolds.
 

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Discussion Starter #12
I am going to try 4-15" drivers in one box which will be centered directly above my front 3 speakers. Amping: just for experimenting before I buy another amp, I will use my ATI AT1506 http://www.wwsp.com/ati/hometheatermagazine.htm . This is a 6ch amp that is currently bridged to power my front 3 speakers (unbridged:150w/ch....bridged:450w/ch). Now the plan is to use 3 unbridged channels for the front 3 speakers, and bridge one set to send 450w to the 4 sub drivers (all 4 drivers will share the single 450w connection).

Here's my thought process (I am no expert at the science of sound, these are conclusions that I have come to through experience and just a semi-smart guy thinking. If anyone disagrees I would like to read your thoughts.):

Why not 2-18" drivers instead of 4-15"?
I haven't done the math, but isn't there more surface area with 4-15" drivers?

Why not use 2 separate manifolds?
1)..More work, more holes in ceiling.
2)..In my experience, multiple subs in multiple locations do not smooth out the sound for multiple listening locations. The multiple distances from listening locations and multiple amping/wiring causes phase and room anomalies. Currently I am using 2 subs (in different locations) with my 2 full range main speakers and it takes hours of tweaking with Audyssey, phase controls, volume controls, and eq's to get them to play well with each other. I'm hoping using multiple drivers at a single location along with a single 450w connection will make them play together well.

Thoughts?
 

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I'm no expert, which is why I posed the question of two manifolds vs one. Before you cut and build, I believe you can experiment to see how viable your IB location will be. Judging by your post, I think you know how to do so.

I think dual Fi 18"s have more displacement when you consider surface area and stroke compared to the four Dayton 15"s, the real conundrum is determining which setup has superior sound quality, and I don't know if anyone has an answer. I think four of the sale priced IB385's are very close in total cost to a pair of the Fi 18's, as in less than $40. I was looking at these two setups myself before putting it on the backburner...
 

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Discussion Starter #14
...Before you cut and build, I believe you can experiment to see how viable your IB location will be. Judging by your post, I think you know how to do so.
Yes, I know how to do the 'sub crawl.' My 2 current subs are not in their optimal position because this is a multipurpose living room and available space is limited.
I really should do it for the ceiling placement. Time to bring in the ladder. Hopefully centered above the main speakers will yield acceptable results.
...I think dual Fi 18"s have more displacement when you consider surface area and stroke compared to the four Dayton 15"s...
I didn't think to consider stroke.
Another reason for choosing 15" drivers is that the LFE channel can have content up to 110 or 120hz (or so I've read on this forum). I believe 15" drivers would handle that better than 18" drivers (another uneducated opinion).
 

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Yes, I know how to do the 'sub crawl.' My 2 current subs are not in their optimal position because this is a multipurpose living room and available space is limited.
I really should do it for the ceiling placement. Time to bring in the ladder. Hopefully centered above the main speakers will yield acceptable results.

I didn't think to consider stroke.
Another reason for choosing 15" drivers is that the LFE channel can have content up to 110 or 120hz (or so I've read on this forum). I believe 15" drivers would handle that better than 18" drivers (another uneducated opinion).
I don't have a dedicated room either, that's one reason why I was interested in an IB. I hope your testing is promising .

When I modeled the two designs, the dual Fi setup could achieve greater spl (headroom), so I figured they would have less distortion for a given output, perhaps someone else can provide input regarding that hypothesis...
 

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Yes, I know how to do the 'sub crawl.' My 2 current subs are not in their optimal position because this is a multipurpose living room and available space is limited.
I really should do it for the ceiling placement. Time to bring in the ladder. Hopefully centered above the main speakers will yield acceptable results.

I didn't think to consider stroke.
Another reason for choosing 15" drivers is that the LFE channel can have content up to 110 or 120hz (or so I've read on this forum). I believe 15" drivers would handle that better than 18" drivers (another uneducated opinion).
I just reviewed the models and for identical output and freq response, the Dayton setup is at xmax (14.3mm) with 180w, while the Fi setup is loafing at 55% of its xmax (18mm of 30mm) with 300w, though it reaches xmax with 800w. You'd be looking at a difference of 112dB vs 116dB at 20hz with both limited by xmax. These occur around 15hz with only a 1st order hpf at 5hz (I use it to account for electronics loss).
 

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Discussion Starter #17
When I modeled the two designs, the dual Fi setup could achieve greater spl (headroom), so I figured they would have less distortion for a given output..
I just checked again on pricing of the Fi IB3 18", for some reason I thought they were more expensive than that. Parts Express lets you ask for a discount for bulk purchases. I don't know yet if they would consider 4 drivers a 'bulk purchase' enough to lower their price cheaper than $125 per.
Rat farts, I hate it when people give me an option.

Anyone have any opinion on my thoughts as to 15" drivers being a better use than 18" because the smaller driver would have better SQ with the higher freq?
 

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Rat farts, I hate it when people give me an option.
Hey! That's what my wife calls me: you haven't been impersonating me Glenn, have you? :rofl:

Seriously, don't make a decision on my account. I'm sure someone else will have suggestions.
 

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Discussion Starter #19
I just reviewed the models and for identical output and freq response, the Dayton setup is at xmax (14.3mm) with 180w, while the Fi setup is loafing at 55% of its xmax (18mm of 30mm) with 300w, though it reaches xmax with 800w.
I'm guessing (never 'assume') this is a comparison of 1 on 1. So if the amount of Dayton 15" drivers is doubled over the Fi 18"er's, then maybe the 15's can handle it reasonably well.

More than likely what it will boil down to for me is if I can get a little bulk discount for buying 4 of the Daytons.
 

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I'm guessing (never 'assume') this is a comparison of 1 on 1. So if the amount of Dayton 15" drivers is doubled over the Fi 18"er's, then maybe the 15's can handle it reasonably well.

More than likely what it will boil down to for me is if I can get a little bulk discount for buying 4 of the Daytons.
The setup's I was referring to were four Dayton's and two Fi's: sorry I wasn't more clear. Efficiency is stated to be nearly the same, it's just that the Fi's have so much more stroke-about double that of the Dayton's.
 
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