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Old 29th March 2008, 10:41 PM   #1
kvk is offline kvk  United States
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Default Help me pick an enclosure project for EVs

Well I figure instead of being easy on myself and starting with a pre-designed project for some Fostex, I'd do something odd ball.

I bought a pair of ElectroVoice Wolverine LT-12 off Ebay. They came yesterday and they work:-) They are a 12" woofer with a whizzer and a little horn tweeter in the center with an L-pad. They're basically a cheaper version of the 12trxb.

So, now I have to decide what to do with them.

Practicality requirements (WAF and also what I think will keep the den nice looking so they have to fit on either side of the fireplace).

2 ft^2 footprint max (so 1x2' or 2x1' or anything like that.)

48 tall max (don't want them to be taller than the mantel is high).

And here's the wildcard. I saw a pair of LT-12 with no tweeters on Ebay (effectively LS-12) and put a teaser bid of $9 in. Ended up getting them for $9 + 17 shipping. So, I have extra woofer/mids too.

I hate long post so I'll post more details in follow-ups to break things up.
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Old 29th March 2008, 10:48 PM   #2
kvk is offline kvk  United States
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Default Options

Possible Designs Types--

Bass Reflex, example specs like –
http://db.audioasylum.com/cgi/m.mpl?...ighlight=LT-12
6ft^3 box w 30 in^2 area by 3.4 in. long port.

MLTL like—
http://www.geocities.com/rbrines1/Pa...168S%20ML%20TL
Click the image to open in full size.

ML TQWT folded like—
http://www.geocities.com/rbrines1/Pa...Fostex%20FE164
Click the image to open in full size.

All those would fit the 2ft^2 footprint although a traditional BR would to short and a bit bigger area.

Open Baffle of some sort --
Initially I thought this would exceed my floor space as many of the designs I see have 3' wide baffles. But maybe I could do something with a 2' baffle or maybe a 2' baffle with 1' fold-out wings or something like that.

I have read MK's MathCad sheet tutorial and played with the sample. I'm not adverse to buying the models if they may help me with this process. Heck, most of the fun will be engineering. I'll take me half the summer to find time to build them and then I'll have 15 minutes a day to listen to them.
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Old 29th March 2008, 10:51 PM   #3
kvk is offline kvk  United States
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Default Theile/Small Driver Parameters

I read a procedure online for determining T/S params.
http://sound.westhost.com/tsp.htm

But I may or may not take the time. I might not do better than what I've found online. Maybe I'll at least check the Fs and Qts.

I searched diyAudio and AA and found some samples I might work with--

From--
http://db.audioasylum.com/cgi/m.mpl?...ight=wolverine
Revc = 5.3515 ohms
Fs = 59.1659 Hz
Zmax = 18.0568 ohms
Qes = 1.6780
Qms = 3.9838
Qts = 1.1807
Le = 0.2776 mH (at 1 kHz)
Diam = 259.0800 mm ( 10.2000 in )
ConeArea =52717.8422 mm^2( 81.7128 in^2)
Vas = 99.8152 L ( 3.5249 ft^3)
BL = 5.7921 N/A
Mms = 28.2967 g
Cms = 255.7180 uM/N
Kms = 3910.5574 N/M
Rms = 2.6405 R mechanical
Efficiency = 1.1877 %
Sensitivity= 92.7470 dB @1W/1m
Sensitivity= 94.4931 dB @2.83Vrms/1m

From—
http://db.audioasylum.com/cgi/m.mpl?...ight=wolverine
[EV - LT12 sample #1]
Fs = 57.000 Hz
Zmax = 38.153 ohms
Re = 5.330 ohms
Zdb3 = 15.224
F1 = 52.771 Hz
F2 = 64.874 Hz
Qms = 13.452
Qes = 1.879
Qts = 1.649
Le = 0.0873 mH
Sd = 591.023 sq.cm
Cms = 0.2356 mm/N
Mms = 0.03309 kg
BL = 5.797 Tm
n0 = 1.10577 %
Vas = 116.397 liters
SPL = 92.455 dBSPL 1W/1M
[EV - LT12 sample #2]
Fs = 60.000 Hz
Zmax = 26.155 ohms
Re = 5.830 ohms
Zdb3 = 13.655
F1 = 54.653 Hz
F2 = 72.865 Hz
Qms = 7.717
Qes = 1.720
Qts = 1.407
Le = 0.1396 mH
Sd = 591.023 sq.cm
Cms = 0.2736 mm/N
Mms = 0.02571 kg
BL = 5.732 Tm
n0 = 1.63633 %
Vas = 135.172 liters
SPL = 94.157

From— http://www.geocities.com/tadgesualdo...arameters.html
LS12 (LS12 is similar to LT12)
Fs: 58.35
Re:6.746
Qms: 7.722
Qes: 2.217
Qts: 1.722
Cms: 0.342 mm/N
Mms: 21.74g
Sd: 557 sq. cm
Le: 0.2 mH
BL: 4.925 N/A
Vas 151 liters
1w SPL: 95dbs

Fs of three different LS12's
Fs A: 58
Fs B: 47
Fs C: 60
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Old 29th March 2008, 11:17 PM   #4
kvk is offline kvk  United States
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Default Wildcard extra drivers

I mentioned the wildcard is I have extra LT-12 sans tweeter (effectively LS-12s) coming.

I saw this--
http://www.geocities.com/tadgesualdo/Speakerplans2.html

I suppose I could do something like that with two drivers, LT-12 in front and LS-12 on top. Don't know how I would model it thought. Even if I buy the MK worksheets, I don't think they do dual drivers. Or maybe a bipole design but the speaker will be close to a wall so drivers in back are not a good idea.



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Click the image to open in full size.
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Old 29th March 2008, 11:18 PM   #5
kvk is offline kvk  United States
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Default Maybe the easiest, fun, hack at it, try something option.

Another option is Open Ballfe with two drivers. That might be cool as if they are narrow (2'), that might help bass. That may the the easier out-of-the-box project to play around. The cost is two 2x4 sheets of MDF and some scrap wood for braces.

One refinement I was thinking of maybe I could take the sans tweeter drivers and put a coil on them at the baffle step point. So instead of using a BSC to cut mid/high, I'd use an extra low driver to boost bass. Don't know what that would do to impedance. I'm going to start with a SS Kenwood KR-7040 receiver which probably could care less. Eventually I hope to build a tube amp in the 5-7W range.
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Old 30th March 2008, 03:56 AM   #6
John L is offline John L  United States
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Gosh, I'm not sure what to recommend, but you are on the right track, it seems to me. Perhaps a TL may not be the best bet, since TLs work better with smaller drivers.

Do you have any software where you can help determine enclosure sizes? Maybe some of the more seasoned regulars can help you out here.
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Old 30th March 2008, 05:32 AM   #7
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Default Re: Theile/Small Driver Parameters

Quote:
Originally posted by kvk
I read a procedure online for determining T/S params.
http://sound.westhost.com/tsp.htm

But I may or may not take the time. I might not do better than what I've found online. Maybe I'll at least check the Fs and Qts.

Hi,
You should find a way to measure these. Fs is not very important, but the Qts is. The T/S samples you found don't look encouraging.
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Old 30th March 2008, 09:41 AM   #8
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Agreed. Q is through the roof = not a great choice for Qw or TL loading if you want it to be of vaguely manageable proportions. OB is about the only reasonable option you've got.
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Old 30th March 2008, 11:52 AM   #9
kvk is offline kvk  United States
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Quote:
Originally posted by Scottmoose
Agreed. Q is through the roof = not a great choice for Qw or TL loading if you want it to be of vaguely manageable proportions. OB is about the only reasonable option you've got.
I believe the EV drivers were originally used in large BRs, somewhat squat that look like pieces of furniture. I tried some of the BR calculators on the web and they don't even work with Q > 0.8.

Again, OB sure would be easy and cheap and I could always do something else in the future without wasting a ton of time and money.
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Old 30th March 2008, 05:20 PM   #10
John L is offline John L  United States
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Something else to ponder. When were these E-Vs made? Remember, Mr. Small did not publish the second half of the Thiele/Small series of revelations until he published his Doctoral thesis in September, 1972. Up until then loudspeaker parameters were still being straightened out, and others also contributed to the information.

Anyway, Dr Thiele's 1961 work was not known throughout the audio world, and J.E.Benson's articles did not come together, until after Mr. Small's doctoral thesis put it all together. This all occured in Australia, where all three worked and were in contact with each other.

I mention this because speakers made prior to this date were not built with T/S parameters in mind. They were simply a play by ear proposition, as were most drivers several years AFTER 1972.

Consequently, if your speakers are truly vintage, T/S measurements will tend to be mute. In other words, you will most likely have to play things by ear, since you cannot rely on numbers that were not taken into consideration anyway.
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