full-range driver for 54lt cabinet?

mimikos

Member
2010-03-14 10:33 pm
hello guys,


a while ago a friend gave to me a pair of diy 54 lt, 19 mm MDF speaker cabinets. These measure 72 cm x 36 cm x 29 cm (external measurements). These are sealed cabinets with no internal bracing and the baffle can be removed and replaced, which means that could be easily modified , add bracing and turn into bass reflex. Not sure if I want to convert them to TL, but I am open to suggestions.

Over the last few weeks I found myself checking out some 8" full range drivers, namely Fostex 207 (looks impossible to find any more), Dayton Audio PS220-8, Audio Nirvana, Audax... I was wondering if anyone could propose me a good match for the size of these cabinets, meaning a decent response down to ~40HZ (bass-reflex most likely)
If needed I could try to extend them in height or depth to increase their volume as long as I get decent results.
I have already found some cabinet plans on the net but I would prefer to hear from those with more experience than me
 
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Well, there are a handful that come to mind that will go into roughly those sort of volumes with a bit of work, so it depends on how much work you want to be doing, what sort of amplifier you'll be using (notably output impedance) & how much money you want to spend. A handful, assuming variations on the vented box theme:

-Cube Audio FC8

-Fostex FF225wk

-Markaudio Alpair 12PW. Wideband so rolled off a little at the top (deliberately) but good for that sort of volume tuned in the mid-low 30Hz regions.

-Markaudio CHR120 (not yet released so depends when you're planning on starting). Designed for similar sort of box sizes.

-Visaton B200. Not a natural fit per se, but their Solo 50 might suit.

-Seas FA22RCZ (well damped with a low tuning)

-Tang Band W8-2145
 
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mimikos

Member
2010-03-14 10:33 pm
Well, there are a handful that come to mind that will go into roughly those sort of volumes with a bit of work, so it depends on how much work you want to be doing, what sort of amplifier you'll be using (notably output impedance) & how much money you want to spend. A handful, assuming variations on the vented box theme:

-Cube Audio FC8

-Fostex FF225wk

-Markaudio Alpair 12PW. Wideband so rolled off a little at the top (deliberately) but good for that sort of volume tuned in the mid-low 30Hz regions.

-Markaudio CHR120 (not yet released so depends when you're planning on starting). Designed for similar sort of box sizes.

-Visaton B200. Not a natural fit per se, but their Solo 50 might suit.

-Seas FA22RCZ (well damped with a low tuning)

-Tang Band W8-2145






that Tang Band looks sweet with a fairly flat response, no nasty peaks, almost too hard to believe for a full range driver..


I certainly cannot afford a $1000 driver but I am happy to spend up to 300 for a pair


My amp is solid state ~50W RMS, 4-8 Ohms. I would prefer 8 ohms speakers though and sensitivity 90-95 db/W/m



Ideally I would like to just replace the old baffle, add bracing, open new holes for drivers and port...and that's it...no extensions or any additional work inside the cabinet..Hence I am mostly interested in bass reflex designs


Unfortunately I don't have any experience with vented boxes. I can play around with winSD for example, but I am not sure how this would translate into sound when the driver is mounted on the speaker cabinet
 

vha

Member
2010-09-28 6:56 pm
I dont have any experience with those drivers of Cube audio,
Impressive look..
I see good specs But I don't recognize how much is the Mms?
Fs = 42 H
Re = 6 ohms
Le = 0.094 mH
Qt = 0.38
Qes = 0.39
Qms =14.3
Cms = 0.81 mm/N
Vas = 55 liters
Sd= 230 cm^2
Bl = 8.6 T*m
Xmax = +- 3 mm*
Xdamage = +- 6 mm
Sensitivity = 92 dB
 
if you look at the vas around that size (54L) and a rather high qts (0.5-0.7), you will be close. If the QTS is lower, the vas needs to be higer and reverse.

but it's always a big guessing without measurements. I think the list of scottmoose will be the safest bets, as he is very experienced with FR drivers in many speakers, and his guess will be based on that experience and knowledge.
 

mimikos

Member
2010-03-14 10:33 pm
do you have a picture of the enclosure?
I don't have right now..but it's as simple as it gets..
literally six panels of MDF glued together.. It is very sturdy I have to admit, no air leaks and overall a very robust construction
There is no finish by the way, just plain MDF which gives too much flexibility..


From my research I am afraid I won't be able to achieve a good response down to 40Hz with these cabinets and probably will need to increase to ~80lt unless there's a special driver that can go down to it in this volume..


From what I've read to this forum Audio Nirvana drivers are pretty good but their proposed bass reflex cabinets are not very well matched, which was kind of my initial decision..
 
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mimikos

Member
2010-03-14 10:33 pm
if you look at the vas around that size (54L) and a rather high qts (0.5-0.7), you will be close. If the QTS is lower, the vas needs to be higer and reverse.

but it's always a big guessing without measurements. I think the list of scottmoose will be the safest bets, as he is very experienced with FR drivers in many speakers, and his guess will be based on that experience and knowledge.
thanks..that should help a fair bit..I assume we are talking about BR cabinets.
I know for example that sealed cabinets like a Q of 0.707 but I am not sure how does this work in BR? Not sure what to expect there and what Q values to aim for
 

mimikos

Member
2010-03-14 10:33 pm
no, i was also talking about sealed, for bass reflex it gets a bit more complex, to complex to do it without modelling a whole leap of drivers in a 54L reflex encllosure untill you find one that fits your needs...
I would prefer a sealed enclosure for its simplicity and the tight bass that offers.

Just had a look on the super 12" ferrite Audio Nirvana with a high Qts of 0.6
....but with a Vas above 100lt that driver would probably suffocate in a 54lt sealed cabinet.
just for ***** and giggles I will give it a try on winSD
 

vha

Member
2010-09-28 6:56 pm
I am in the same path with you and still looking.... and I see that it is difficult to find a FR driver with low Qts that can provide low frequencies in sealed enclosure.
I started looking in high power pro drivers with high sencitivity and low Mms
Lets say in summary
Low Fs
high SPL
Low Qts
Qms above 6
Large Xmax
large Vas (for stiffnes of the driver)
 

mimikos

Member
2010-03-14 10:33 pm
sorry..just a bit confused ..is it Qes or Qts the parameter that defines whether a driver is appropriate for sealed or bass reflex cabinets?
I had the impression that stiff suspension drivers are more suitable for bass reflex



Nonetheless, regarding a sealed cabinet should I aim for high or low Qts?