Which helper woofer in open baffle would you pick?

I'd like to use a helper woofer with my Tang Band 1808 in a low, wide open baffle design. I've been looking at these two, partly because of the price and the high Qts: the GRS 12FP-8, and the Eminence Alpha 12A. I plan to crossover to the Tang Band at around 200 Hz using an active crossover. One downside to the GRS is the lower sensitivity - since I'll be using an active crossover its not as big an issue, but I'd like the option of later building a passive crossover to allow use of just one amp if desired, and the GRS would probably disappear in that event. I've about settled on the Alpha. Any other reasonably priced contenders I should consider, and do you agree that I should go with the Alpha?
 
Historically, one acoustically fit the driver to the baffle, i.e. matched the driver's mass corner (2*Fs/Qts) to the baffle's effective width with a Fs ~a half octave below the baffle cut-off, though nowadays EQ is used to shape its response, so whatever driver is within budget that has a low enough Fs for the baffle size + any boundary loading and high enough Xmax/power handling and/or high Qt (up to ~1.5 depending on the desired mass corner) to meet the SPL desired.

Easiest to just try different drivers in Basta!, MJK's MathCad OB worksheet or similar.

GM
 
Historically, one acoustically fit the driver to the baffle, i.e. matched the driver's mass corner (2*Fs/Qts) to the baffle's effective width with a Fs ~a half octave below the baffle cut-off, though nowadays EQ is used to shape its response, so whatever driver is within budget that has a low enough Fs for the baffle size + any boundary loading and high enough Xmax/power handling and/or high Qt (up to ~1.5 depending on the desired mass corner) to meet the SPL desired.

Easiest to just try different drivers in Basta!, MJK's MathCad OB worksheet or similar.

GM

Thank you! I must say, that is a well crafted explanation. A taut construction of intuition and engineering terms complementing each other; left-right-left-right-knockout.
 
I accidentally recently ordered some Alpha 12's instead of the Beta12A2s. Because it will cost me 15 bucks to send back a pair of the Alphas I tried really hard to fit them into any project I could conceivable start.

They're in the box and going back. They're really about half a speaker, and for another 10 bucks you can get a real one. I'd suggest to figure out an electronic/electrical way to control the Q for the OB application and use a Beta.

I don't know what your amp situation is like but the Alpha 12A is probably only quite reasonable down to 50Hz OB if you have less than 15 watts to work with or something.
 
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Gyuri

Member
2003-11-03 6:47 pm
Budapest
I'm to trust in Papa's wisdom.
I bought it because of this two Beta15A loudspeaker.
I do not know when will be I dealing with this will be my time and my energy.
I do not know it, how I join these to my system.
I am watching all experiments like this with enquiring because of this.

Gyuri
 
One other possibility I'm mulling over - I have the original drivers, they just all need to be reconed and/or refoamed. I could just reuse the original Super 12s. That presents its own set of problems (although eventually I planned to eventually repair all the drivers and listen to the speakers in near original condition as an exercise in nostalgia and economy stimulation). The major issue would be very limited volume as the original speakers were only rated for 15 watts (and thats the whole speaker system, not just the 12s). They're also 16 ohms (IIRC), so my plan of an active crossover with a beefy solid state amp to the woofers would be kind of silly, and a passive crossover would also be problematic.

Anyone have suggestions for refoam kits for the Super 12s?

Any more suggestions for a modern 12 that can work well in open baffle? I'm not planning to drive it with EQ to try for much output below about 70 Hz or so - I'll use some subs if I want LOW bass. I need assistance for the full range from about 70 to 200 Hz. Optimally it would be pretty sensitive, able to take upwards of 100 watts, with a Qts between about 0.7 and 1.2, and not very expensive.
 
Mash, agree with you on that. The Alpha 15 sims better than the 12 on ob... probably bc of it's larger diameter and higher qts. I spent a couple hours today listening to Wicked with my wife... the Alpha's in H-frames shine! The Beta 15 does look like a great value. It appears more robust and 'worth it' for a few bucks more. I've not heard them but i do enjoy the Alpha 15 a lot.

There was a 12" Jamo that's no longer available at PE that would have been perfect for you RS... but it's no longer in stock. I was going to recommend it for you. There are a few Goldwoods and GRS with specs 'good enough' for OP but you will require an amp to bring up the volume with the TB. Maybe consider looking for a sub amp that will power them. Added cost but i think the extra amp would allow you to accomplish your goal.
 
I have 4 X Beta 15As still sitting in boxes because I cannot get them to
simulate as well on open baffle as the Alphas. The Betas roll off more quickly and run out of xmax as well. I would be interested to hear from anyone, including Papa, as to what they did with theirs.

I hope I am not hijacking but I think the earlier rolloff might be relevant to the thread.

At this point I don't know whether I will go ahead with open baffles.\
jamikl