[versus rider]

Hi guys, pre-empting the need for two alpha's a side in open baffle if its beneficial that is. I have been running my open baffles for some time now and decided after suggestions from others that the 8" full range might benefit from a bit of assistance from a tweeter taking some of the frequencies. Have found when the music gets busy it struggles. So I have bought a pair of tractrix 1000Hz horns and BMS compression drivers from stereo labs in Germany and today tried them with my office system , comprising diy bass reflex full range standmounts, usually accompanied by audax horn loaded tweeters and a 300B amp. Well they are in a different league to the audax but not nearfield like I listen in the office. I haven't yet had time to run them with the OB's but will as soon as is possible. Now the 8" drivers I am using are sourced from someone I have become acquainted with over time and is a bit of a mentor. He has now designed a front horn for the 8" drivers that works down to 150Hz, which got my attention as most all of the horns I have seen work down to 300Hz, which is far too high for the alpha's in my baffle. I should say that I am running one driver for each side. Now the point I was getting to is would two drivers wired in parallel at 4 Ohms give a higher output than the one 8 Ohm driver, as this may be of benefit when coupled with the higher efficiency of the front horns. I should also point out that I am tri-amping via a digital crossover .

[Morfeus]

Two Alphas will give you ~6dB more than one.

But as you run active I don't see why you should do that, as you simply can give the one Alpha more power.

[versus rider]

good point

[holdent]

Two Alphas will allow higher SPLs and lower distortion than one for the same SPL.  So depending on your application you might want two per side.

[painkiller]

Definitely go for two drivers on each side. A little more headroom never hurts. The Alphas have severely limited Xmax for OB. I easily drive mine to the Xlimit with a 50W amp. 

[panomaniac]

Two for sure!  As noted above, lower distortion.  Also 2 woofers just sound bigger, even at the same spl, than 1.
And if you run a passive crossover you can use an inductor 1/2 the size.

[versus rider]

any more votes for two? sounds like it could be the way forward. As I am running a spheric wave horn from 2Khz up and soon a tractrix horn with direct radiator from 150Hz to 2Khz I may find the extra spl of benefit or even essential given the spl of the horns. Unfortunatley my baffle design is looking like being redundant and a new one for the bass only with a flat top to stand the tractrix on being made.

[JohnR]

If you have a digital xover (what is it, btw?), then why not just use one Alpha, and then use subs "underneath" whether sealed or OB, to bring up the bottom.

[scorpion]

Given your outfit I would seriously consider a many (at least double) folded Tapped Horn, these can have the same irresistable qualities as OBs but with a much higher effeciency and even precision. More folds will take them higer in linear frequency response. Look for instance at Volvotreter's 30 Hz Tangband TH: http://www.volvotreter.de/th.htm just use 3/4" thick ply for the enclosure.

Going OB I would vote for 2 AE IB15s per side as the budget choice for US customers.

/Erling

[panomaniac]

The real manly OB bass choice in the US is two Goldwood GW-1858 18" woofers per side.  Now that rocks!  Clean, too.  Once heard, never forgotten.  All the way down to 16Hz.

[versus rider]

had a quick look at the tapped horn article and saved it to study closer, thanks for that. the alphas are the best option for me in the UK, 

Given your outfit I would seriously consider a many (at least double) folded Tapped Horn, these can have the same irresistable qualities as OBs but with a much higher effeciency and even precision. More folds will take them higer in linear frequency response. Look for instance at Volvotreter's 30 Hz Tangband TH: http://www.volvotreter.de/th.htm just use 3/4" thick ply for the enclosure.

Going OB I would vote for 2 AE IB15s per side as the budget choice for US customers.

/Erling

[djn]

My room is 6142 cubic feet and that does not include the hallways or kitchen at the back and I run 2 "H" frames with one Alpha in each.  I do not feel the need for any more Alphas.  I listen to a variety of music and the Who's Whos next does not strain them at all.  And, stand up bass sounds like it is in the room with me.

[FullRangeMan]

As any woman can attest bigger is better.  I just wish to know what is the inductor value for two Alphas??
Cutting at the usual 280-300Hz frequency.
Regards, Gustavo

>Never go to a psychiatrist, adopt a cat or dog from the street. On the streets they live only two years average.

[FullRangeMan]

The real manly OB bass choice in the US is two Goldwood GW-1858 18" woofers per side.  Now that rocks!  Clean, too.  Once heard, never forgotten.  All the way down to 16Hz.

After seen the Goldwood site at the Pismo series, I could suggest these two Goldwood 15 inches, one have a huge QTS = 1,952, SPL is low though, great drivers for a OB panel.

http://www.goldwoodsound.com/Woofers4_files/GW2158.pdf

http://www.goldwoodsound.com/Woofers4_files/GW215408.pdf

>Never go to a psychiatrist, adopt a cat or dog from the street. On the streets they live only two years average.