Bush & Bass OB (advice?)

trilateral · 5th July 2007, 08:10 PM

Hi, I've beening tryng to figure out a reasonably priced OB and wondered if anyone would like to make comment on what I've come up with.

Hemp FR6.5C and Eminence Alpha 15 with active crossover (around 200Hz) and EQ, powered by 2 x TA-10.1s on an 18 x 36" baffle. I've ran the specs through xbaffle.xls and it looks like a winner to me (45-20k with just a slight rise in the upper end)... but then I'm total novice!

Anyone like to comment on the feasability of it working?

xbaffle graph

happy.gringo · 6th July 2007, 01:40 PM

It seems to me that a Trends would be underpowered for bass duties. How about this amp for the woofers:
http://emotiva.com/bpa1.html

trilateral · 6th July 2007, 02:09 PM

Nice, they do look tasty! Fairly cheap too. Though the fan and 150Hz cut off point might be a problem. Point taken though, the trends are a bit lacking in power for bass duties, it's just that I have a a few spare.

PS has anyone hear listened to the Hemp FR6.5C, any reviews yet?

Scottmoose · 6th July 2007, 02:28 PM

FE167E wired & XO'd (~180Hz) in series with Eminence Beta 15 on a tapered U-frame approx 48in x 18in x 16in (HxWxD -latter at base, tapering to nothing at the top) works well with about 2w input. I don't have all the details but that's roughly what is used, and believe me, they sing. Work pretty well near walls & corners too. This is JamesD, with a pair that he designed for NickG. They vanish into the soundstage. Every time I hear them, I go hunting for the XO. No sign of it at all. James's Quasars, with AER MK1 & Supravox 285 woofers are seen alongside.

ronc · 6th July 2007, 02:34 PM

I like that, nice and simple! Is the woofer rolled off at 180?

ron

Scottmoose · 6th July 2007, 03:16 PM

Yeah, AFAIK. Round about there anyway -I think they're still tweaking, not that I can hear any need for it. They're using the natural LF roll-off of the 167 on the baffle to minimise the number of components required too. I like.

Not lacking for LF grunt either -the bottom octave of Metallic's live S&M album with the SF Symphony Orchestra shakes the windows.

ronc · 7th July 2007, 01:32 PM

Sounds to me like the only XO component is a cap across the woofers pins, maybe a resistor also (RC) to roll off the woofer.

This is a dang good example of a simple alingment that could be accomplished by just about anybody. The impedance with the above (series) would overlap somewhat, but if the distance between the CL of the drivers was < 1/2, @ XO, wavelength there should be a good blending of SPL between the two even at the greater resistance.

ron

trilateral · 7th July 2007, 07:33 PM

Quote:

Originally posted by Scottmoose
Yeah, AFAIK. Round about there anyway -I think they're still tweaking, not that I can hear any need for it. They're using the natural LF roll-off of the 167 on the baffle to minimise the number of components required too. I like. Not lacking for LF grunt either -the bottom octave of Metallic's live S&M album with the SF Symphony Orchestra shakes the windows.

Would you think the wings on the baffle would help with placement (proximity to walls)? I was thinking a high Qts for the bass, but maybe a lower Qts with wings might be better.

Also, loving those perspex baffles. I've just secured some scrap sheets from a collapsed smoking shelter, so should be able to put them to some good use.

Scottmoose · 7th July 2007, 08:31 PM

Yes, they do. As-is, these baffles work perfectly acceptably near a wall, or even a corner. They're far better pulled out into a room, obviously, like any baffle is, but still not too bad at all. The notion as I understand it is that the polar response increasingly shifts toward a cardioid, rather than a dipolar figure-8 pattern with decreasing frequency. That's overly simplified -Linkwitz points out that a pure U-frame can't actually achieve a perfect cardioid polar response, but there's no doubt that they do become increasingly directional in the LF, which makes them remarkably position-friendly.

In all honesty, these cheap baffles James designed give some of the best sounds I've ever heard. They're not perfect by any stretch of the imagination, but they're very special. I remember sitting about 8ft from them at the recent Owstfest event, and they dissolved. All that was left was a vast, wrap-around Cinemascope-esque soundscape. Remarkable.

FlorianO · 8th July 2007, 09:46 PM

Quote:

Originally posted by Scottmoose
They're not perfect by any stretch of the imagination, but they're very special

And what exactly is the fly in the ointment ?

TIA,

Florian

5th July 2007, 08:10 PM	#1
trilateral diyAudio Member Join Date: Jul 2007	Bush & Bass OB (advice?) Hi, I've beening tryng to figure out a reasonably priced OB and wondered if anyone would like to make comment on what I've come up with. Hemp FR6.5C and Eminence Alpha 15 with active crossover (around 200Hz) and EQ, powered by 2 x TA-10.1s on an 18 x 36" baffle. I've ran the specs through xbaffle.xls and it looks like a winner to me (45-20k with just a slight rise in the upper end)... but then I'm total novice! Anyone like to comment on the feasability of it working? xbaffle graph

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6th July 2007, 01:40 PM	#2
happy.gringo diyAudio Member Join Date: Sep 2005	It seems to me that a Trends would be underpowered for bass duties. How about this amp for the woofers: http://emotiva.com/bpa1.html

6th July 2007, 02:09 PM	#3
trilateral diyAudio Member Join Date: Jul 2007	Nice, they do look tasty! Fairly cheap too. Though the fan and 150Hz cut off point might be a problem. Point taken though, the trends are a bit lacking in power for bass duties, it's just that I have a a few spare. PS has anyone hear listened to the Hemp FR6.5C, any reviews yet?

6th July 2007, 02:34 PM	#5
ronc diyAudio Member Join Date: Mar 2003	I like that, nice and simple! Is the woofer rolled off at 180? ron

6th July 2007, 03:16 PM	#6
Scottmoose diyAudio Member Join Date: Mar 2005 Location: UK	Yeah, AFAIK. Round about there anyway -I think they're still tweaking, not that I can hear any need for it. They're using the natural LF roll-off of the 167 on the baffle to minimise the number of components required too. I like. Not lacking for LF grunt either -the bottom octave of Metallic's live S&M album with the SF Symphony Orchestra shakes the windows.

7th July 2007, 01:32 PM	#7
ronc diyAudio Member Join Date: Mar 2003	Sounds to me like the only XO component is a cap across the woofers pins, maybe a resistor also (RC) to roll off the woofer. This is a dang good example of a simple alingment that could be accomplished by just about anybody. The impedance with the above (series) would overlap somewhat, but if the distance between the CL of the drivers was < 1/2, @ XO, wavelength there should be a good blending of SPL between the two even at the greater resistance. ron

7th July 2007, 08:31 PM	#9
Scottmoose diyAudio Member Join Date: Mar 2005 Location: UK	Yes, they do. As-is, these baffles work perfectly acceptably near a wall, or even a corner. They're far better pulled out into a room, obviously, like any baffle is, but still not too bad at all. The notion as I understand it is that the polar response increasingly shifts toward a cardioid, rather than a dipolar figure-8 pattern with decreasing frequency. That's overly simplified -Linkwitz points out that a pure U-frame can't actually achieve a perfect cardioid polar response, but there's no doubt that they do become increasingly directional in the LF, which makes them remarkably position-friendly. In all honesty, these cheap baffles James designed give some of the best sounds I've ever heard. They're not perfect by any stretch of the imagination, but they're very special. I remember sitting about 8ft from them at the recent Owstfest event, and they dissolved. All that was left was a vast, wrap-around Cinemascope-esque soundscape. Remarkable.

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