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Help me finish these boxes.

jvstratman

jvstratman

Well-Known Member
My current setup consists of a Fisher 400 w/ Pioneer HPM 100's and a Kenwood KR-8010 w/ 87 Forte's. I run A Sony CDP-CA80ES CD changer to both amps thru a splitter. The sound coming from this room is amazing. The Kenwood can run 2 pairs of speakers simultaneously by selecting A+B. I want to try that. Will this take away from the Fortes? They cannot be controlled separately with this amp.

I recently refinned a beautiful pair of empty walnut cabs my brother built 30 years ago. I fitted them w/ older Sansui grills - They're Stunning! The baffle accepts a 12" speaker located in the middle. I'm looking for suggestions on a 12" full range Woofer/Driver. If I'm better off pitching the baffle and going in another direction, say so and why. The cab dimensions are 14" x 14" x 25".

BTW, I use the Fisher/HPM's for bass/mids and the Kenwood/Fortes for mids/highs. The Kenwood "B" (currently empty) speakers sit atop the HPM's on either side of the rack. The Fortes are on 20" risers in the corners. What would you choose for the empty cabs? Please don't say another amp...
 
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I am curious as to why you would want to run two different models of speakers simultaneously. All kinds of phase cancellation problems can happen, not to mention the load it can put on your amp.

As far as a full range driver goes, the Electro-Voice 12txrb is an excellent triaxial driver, and would respond well with your Fisher 400. (my favorite receiver, btw)

Regards,

Ken
 
Also, a point you may not be aware of is the KR-8010 put the speakers in series when you choose A+B and your audio level on the speakers will drop. By doing this the receiver protects itself from too light a speaker load. The secondary byproduct of this is that the 120watt rating for the receiver is diminished a good bit and the amp can be driven into clipping earlier that you would expect. Be careful out there, it cost me a pair of woofers on mine.
 
Glad I asked. The last thing I want is to diminish the performance of the Fortes or damage any equipment.

So far it sounds like it might be a good idea to nix the A+B idea and use these with another amp perhaps in another room.

I'll google the Electro-Voice 12txrb drivers.

Thanks folks!
 
EV 12TRXB is not in my database, but if the T/S parameters are the same for 12TRXC, I can't make it work in those 2.0 cuft cabinets except closed box (red, bottom).

However, that IS an optimum size box for Hi-Fi 32 Hz tuning of vintage JBL LE14A (black,) and yes, their "squircle" frames will fit in 14" wide cabinets, such as my S99 "Hotrods," below. They're good (-10 dB) to 28.5 Hz, substantially better than 12TRX's 52 Hz, i.e., they'll play nearly a full octave lower.

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Read up on playing multiple speakers in the same listening space here:

http://audiokarma.org/forums/showthread.php?t=109584
 

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Hey Z, just curious what you use for measurement. Obviously you have Bassbox 6 and that looks a lot like a Behringer ECM8000 mic in the picture. What software do you use it with?

So as to not completely hijack the thread...the Audio Nirvana 12" has a following but I don't think it likes boxes your size a quick check says ~70Hz low end. I've had decent success with the Eminence Beta12CX and APT50 tweeter combo but I think the box was a bit bigger, it's been a while.

Edit: sorry didn't catch the Zilch used f10...with the Audio Nirvana the -10 point would be around 43Hz.

Ray
 
I was also thinking about the Beta 12 CX, but I'd suggest a different horn driver on the back. The Selenium D210Ti.

Looks like you could cross over the Selenium (in a home application) at around 1600-1800 Hz, unlike the APT50 (which really, shouldn't be used below about 3500 Hz).

At that point (around 1800 Hz), the crossovers would be pretty easy... a low-Q (highly-damped) highpass crossover on the D210Ti, and a low-Q lowpass on the woofer part, with a notch filter to yank down the peaky nonsense at around 3K-4K or so.

Probably could be made to sound REALLY GOOD... if you were really clever, you have enough "extra efficiency" on the horn driver, to use a "shelf filter" (resistor and cap in series) to boost the response above 15Khz. Might be able to get 55-20000 Hz response, plus or minus 3 dB, if done right... f10 in the high-30-something-Hz range for bottom end extension, too...

Regards,
Gordon.
 
Sounds like a winner, Gordon. When I used the Beta12CX/APT I crossed around 2500 and backed off the power a bit. It was probably a bit rough on the tweeter but you could get ear bleeding volume pretty easy with a 96ish dB sensitivity and not get a ton of distortion. It was designed for conference center ceilings so uber HiFi wasn't first on the priority list. They wanted "loud and clear" first and foremost for speech intelligebility and background music after that.

FWIW, the APT-50 (slightly modified) is what was used in the Adire HE10.1 that reviewed well. I don't know where it was crossed over though.

I don't think I've heard that particular Selenium but I do respect the brand. It's hard to go wrong with their compression drivers.

Ray
 
spkrdood said:
Hey Z, just curious what you use for measurement. Obviously you have Bassbox 6 and that looks a lot like a Behringer ECM8000 mic in the picture. What software do you use it with?
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Good call, Ray!

The Behringer mic I use with their UltraCurve DEQ2496 RTA.

For serious design work, it's MLS using CLIO, some of which I've posted here, but the RTA is running all the time on that, too.... :thmbsp:

Most all of my designs are two-ways using compression drivers on horns crossed at 800 Hz - 1.5 kHz for mids and highs. I've sure gotten nice results with the Altec 811 and 511 horns recently, but my standard fare is JBL Progressive Transition waveguides, like what's in my "Hotrods," above. Those are the 100° x 100° dispersion pattern, but I like the 90° x 50° version (more like the Altecs) as well. No tweeters HERE, nope, nope.... :p:

Edit: I sure hope readers are getting this: You can't just toss drivers in a box and expect optimum (or even decent) results. Ray and Gordon have tons of experience building speakers. The tools for doing this are available and easy to use. All it takes is a willingness to explore and apply the fundamentals.... :yes:
 
Zilch said:
I sure hope readers are getting this: You can't just toss drivers in a box and expect optimum (or even decent) results.
Click to expand...

Yeah, I got it. Could he not port that cab and use the E/V 12trxb?
 
Urizen said:
Yeah, I got it. Could he not port that cab and use the E/V 12trxb?
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Find the parameters for that driver, and let's compare to 12TRXC, which I do have. If they're different, I'll load 'em up and run the curves for comparison.

ISD Online needs only Vas, Qts, and Fs for a basic box design.

WinISD is cool, because you can set the box volume at Jvstratman's 2.0 cuft and vary the port tuning for any chosen driver by sliding your mouse, and watch the curve shape change accordingly.... :yes:
 
Urizen said:
Will this help?

http://www.geocities.com/michael_gesualdo/12trxbdatasheet.html
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Yup. That'll get it:

http://www.geocities.com/tadgesualdo/12trxbTSparameters.html

Just a couple of the parameters are different from 12TRXC, and I uploaded them to the BB6P database and modeled the 2.0 cuft ported box using them, below:

1) 12TRXC, black

2) 12TRXB, red

3) In minimum box size EV recommended, 3.5 cuft, green

4) In maximum box size EV recommended, 8.7 cuft, orchid

Curves are for BB6P suggested box tunings, optimally flat for each box size. Looks like they all rather suck, is what, with 3 - 6 dB of boom, plus poor bass extension in the 2.0 cuft cabinets.

Closed-box remains the preferred alignment for 12TRXB in Jvstratman's cabinets, blue in the second image, but better bass can be easily obtained with alternative drivers.

If anyone has a specific tuning for 12TRXB in 2.0 cuft to propose, I'd be pleased to confirm it here.

That driver wants EBS tuning in a larger, heavily damped box, according to BB6P....
 

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Zilch said:
If anyone has a better specific tuning for 12TRXB in 2.0 cuft to propose, I'd be pleased to confirm it here.
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Don't know about "better" but when i saw the high Q hump in that 2ft box I started dorking around with dropping the tuning frequency to ridiculous levels. It kind of gets better if you go with about 8 or 10Hz tuning but the port is completely unrealistic so it would need a passive radiator. I didn't look at PR specs that would be needed to see if they're even physically possible. However, the sealed box still looked better and I didn't think jvstratman wanted to massacre his spiffy boxes with a PR cutout so I just left it alone.

The EBP for that driver is 60 so putting it in a ported box is forcing the issue quite a bit anyway. Fun exercise though!

Ray
 
spkrdood said:
The EBP for that driver is 60 so putting it in a ported box is forcing the issue quite a bit anyway. Fun exercise though!
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Yup, yup!

For those new to this, EBP is Efficiency Bandwidth Product, very simple to calculate.

EBP = Fs/Qes

For 12TRXB, that's 45/0.75 = 60

Driver with EBP equal to or below 50 wants closed box, equal to or above 100, a vented alignment; in between, it's a preferential continuum.

So, by looking at those two numbers, it's easy to tell what to do with a woofer for optimum performance.

There's exceptions, of course, and other strategies to explore, but even if you can't locate the parameters for a particular driver, it's pretty easy to measure them and get a "handle" on a basic design approach for any woofer.... :thmbsp:
 
spkrdood said:
Don't know about "better" but when i saw the high Q hump in that 2ft box I started dorking around with dropping the tuning frequency to ridiculous levels. It kind of gets better if you go with about 8 or 10Hz tuning but the port is completely unrealistic so it would need a passive radiator. I didn't look at PR specs that would be needed to see if they're even physically possible. However, the sealed box still looked better and I didn't think jvstratman wanted to massacre his spiffy boxes with a PR cutout so I just left it alone.

The EBP for that driver is 60 so putting it in a ported box is forcing the issue quite a bit anyway. Fun exercise though!

Ray
Click to expand...

I had the same thoughts... an Adire-style small vented box with a really low tuning. Gets the power handling back up, in the low end, compared to a sealed box (ie, the woofer won't "bottom out" or distort as quickly as a sealed enclosure would cause).

Passive radiators could be done... it'd take a HUGE mass on a small diaphragm, though. As Ray said, it might not be practical. I'd guess something like a KILOGRAM or a KILOGRAM AND A HALF (2 to 3 lbs!) of mass on a 12" passive radiator, to even get in the ballpark. Don't know of many suspensions besides the TC Sounds or maybe AE Speakers passive radiators, that could even remotely handle THAT much weight hanging on the diaphragm.

Personally, given the low excursion capacity of a 12TRXB, I'd be tempted to used them differently... as a midbass/fullrange, with a dedicated subwoofer to handle under 80 Hz or so. Put them in an aperiodic (variovent-tuned, similar to the Dynaco A25 enclosure style) enclosure to kill the bottom end "boom" (make them flat down to whatever rolloff frequency) and bring in a sub to handle everything from there down...

For this case, since he's not even bought drivers yet, I'd be inclined to use something a bit more conducive to success, in his enclosure... hence, the suggestion of the Beta 12 and such. The Beta12CX might not be quite optimal, but it's a LOT CLOSER than the 12TRXB, in this box!

Regards,
Gordon.
 
With a Pe of 250 watts and 97 dB 1W sensitivity, Eminence Beta-12CX is a LOUDspeaker. However, with Xmax of only 3mm, it's not gonna do well for extended bass in conventional alignments. Usable LF response down to only 66 Hz, according to the spec:

http://www.eminence.com/pdf/beta-12cx.pdf

EBP is 84, so it's more toward a ported-box driver, but BB6P says it wants 8 cuft for Hi-Fi or 11 cuft for Extended Bass alignment. Here's how it behaves in Eminence's recommended minimum 1.25 cuft vented box:

http://www.eminence.com/pdf/cab-beta-12cx.pdf

Scroll down that page for their exposition of various alignments, similar to what we're exploring here.

It'll play closed-box in 2.0 cuft (black,) but here again, 46.5 Hz is about the limit of usable bass (-10 dB).

Vented, it'll play a bit lower, 42 Hz, but it's starting to boom at 100 Hz (red).

The shape of that curve is reminiscent of a familiar driver in a too-small vented box, which I'm going to suggest as another option here, JBL 123A-x, the L100 woofer, which'll play very nicely down to just below 30 Hz in a 2.0 cuft heavily damped closed box (blue).

[Gordon's got a pair or two of those, I believe.... ;) ]
 

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"I'm looking for suggestions on a 12" full range Woofer/Driver. "

Don't know about your box dimentions but you might look into a JBL D123 Extended Range 12 inch driver.
 
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