Bruce + subwoofer

broughd · 12th December 2007, 09:18 AM

Hi

I have been following the Frugal-Horn thread with much interest and am looking at building 5 Bruces for HT and HiFi (2 to start with to see how they sound) and was wondering if anyone has any comments on whether they are suitable to match with a subwoofer, either infinite baffle or Labhorn.

Has anyone tried this approach? The Bruce should play quite loud if it is only handling 80hz up and the crossover region should be quite smooth as the frequency response of the Bruce is quite flat at that frequency.

Would the Labhorn be overkill for these speakers? I guess at least I wouldn't need a powerful amp to drive it!!!

Is this a reasonable line of thinking or am I missing something?

cheers - DB

tpakkanen · 13th December 2007, 06:57 PM

Hello,

I've a bit smaller type of Bruces this summer and I'm really pleased with them. After reading the Tapped Horn thread over and over again I decided to try to build one to my Bruces with the lower end.

The result is excellent. The tapped horn integrates nicely to Bruces. One thing that I'll might add is a feedback destroyer to get room modes eliminated.

I use old Yamaha amplifier for the sub, maybe 30W used...

So, I would recommend a tapped horn. Build a prototype and try it =)

--
Tuomas

Scottmoose · 13th December 2007, 07:05 PM

Oh yes. Nice combination indeed.

You can never have too much LF grunt & extension. Just back-off on the old volume knob or damp the thing if necessary.

broughd · 14th December 2007, 10:29 AM

tpakkanen and Scottmoose

Thanks for you comments as someone who has built something similar to what I have described!

Good to hear that your tapped horn worked well with the frugel horns... what crossover frequency and slope do you use? and are the mains highpassed or full range?

I'm not into insane volume levels (as Scottmoose said in another thread >85db = hearing damage), I just like plenty of headroom. I also like distortion free low bass extension. The room they are going into is a decent size too. Actually what I really like is for the sound to sound 'real'. That is what attracted me to the frugel horns - and their lack or crossover, and their good efficiency which should lead to low phase/compression/IM/harmonic distortion? I guess I'll know for sure once they are built...

Thanks Scottmoose for designing the frugel horns! Once I have completed mine I'll post the results back to the main thread.

cheers, DB

Scottmoose · 14th December 2007, 11:31 AM

I've only ever built a quick tapped horn test-box for an 8in woofer I had lying around -it was never in the main system (no room). But it gave me a good idea of their signiture & it's a good match to most things, providing they have a sense of scale, which a BVR has.

tpakkanen · 14th December 2007, 02:41 PM

At the moment the tapped horn crossover is at 40Hz from my AV-reciever and Bruces are running full range. To my ear this sounds the best compination.

The bigger the room is, the better Bruces sound =) I think that Bruces needs some free space behind them.

yours,

--
Tuomas

broughd · 14th December 2007, 09:18 PM

What were the frequency cutoffs of your tapped horns?

I would have thought the boxes would have to be quite large to go much under 40hz right?

I've got a 12" carbon fiber driver lying around that has an fs of 22hz and QTS of 0.29. I have been trying to figure out what to use it for and I think and a front loaded bass horn seems like a good option, being carbon fibre, cone should be light and strong, good for horn loading, has a big magnet too!

At 0.29 the QTS is probably too low for tapped horn isn't it?

I tried running it full range and it sounded ok up to 1khz or so but then it beams horribly and seems to have some breakup resonances or something.

cheers, DB

Scottmoose · 14th December 2007, 10:06 PM

A bit. Fp of mine was 25Hz, which really was pushing the driver too hard. It wasn't supposed to be especially refined though, just a quick 'try it for fun'.

broughd · 14th December 2007, 10:20 PM

Fp?

ronc · 14th December 2007, 10:43 PM

just a quick 'try it for fun'

I use an old RS1354 for tests. Wip up some styro panels with glue and test.

Which leads me to another type of Mfg. process. I studied the baffle shape and the front panel of the A166 (currently in SC). Without extensive, and costly, woodworking there was no way to get the suprabaffle/front panel to the desired shape that i saw as being efficent. I was looking for a more teardrop shape of the suprabaffle and a vertical radius, which blended into the suprabaffle, on the front baffle. This sim gave me the least edge diffraction and less direct reflections off the front panel.

Now , in the old days when we wanted a shape to test we would build a styro male mold and using as a release medium a cover of Saran wrap then overlay the mold with impregenated (rosin) fiberglass. This is the method used by Mr. Bede on his kit planes and the method i am using on my HY PO trike models for aerodynamic studies.

So to achieve the desired shapes on the A166 i will be using the above method. As i have acccess to a CMM the layers will be built up and ground down until the two horns match within a given tolerence.

Should be interesting. I just want to bring the A166 up to its total full potential.

ron

As an added note, i rejected the use of Carbon fiber in this application due to the cost and the need to vacumme form.

12th December 2007, 09:18 AM	#1
broughd diyAudio Member Join Date: Oct 2007	Bruce + subwoofer Hi I have been following the Frugal-Horn thread with much interest and am looking at building 5 Bruces for HT and HiFi (2 to start with to see how they sound) and was wondering if anyone has any comments on whether they are suitable to match with a subwoofer, either infinite baffle or Labhorn. Has anyone tried this approach? The Bruce should play quite loud if it is only handling 80hz up and the crossover region should be quite smooth as the frequency response of the Bruce is quite flat at that frequency. Would the Labhorn be overkill for these speakers? I guess at least I wouldn't need a powerful amp to drive it!!! Is this a reasonable line of thinking or am I missing something? cheers - DB

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13th December 2007, 06:57 PM	#2
tpakkanen diyAudio Member Join Date: Nov 2004 Location: Finland	Hello, I've a bit smaller type of Bruces this summer and I'm really pleased with them. After reading the Tapped Horn thread over and over again I decided to try to build one to my Bruces with the lower end. The result is excellent. The tapped horn integrates nicely to Bruces. One thing that I'll might add is a feedback destroyer to get room modes eliminated. I use old Yamaha amplifier for the sub, maybe 30W used... So, I would recommend a tapped horn. Build a prototype and try it =) -- Tuomas

13th December 2007, 07:05 PM	#3
Scottmoose diyAudio Member Join Date: Mar 2005 Location: UK	Oh yes. Nice combination indeed. You can never have too much LF grunt & extension. Just back-off on the old volume knob or damp the thing if necessary.

14th December 2007, 10:29 AM	#4
broughd diyAudio Member Join Date: Oct 2007	tpakkanen and Scottmoose Thanks for you comments as someone who has built something similar to what I have described! Good to hear that your tapped horn worked well with the frugel horns... what crossover frequency and slope do you use? and are the mains highpassed or full range? I'm not into insane volume levels (as Scottmoose said in another thread >85db = hearing damage), I just like plenty of headroom. I also like distortion free low bass extension. The room they are going into is a decent size too. Actually what I really like is for the sound to sound 'real'. That is what attracted me to the frugel horns - and their lack or crossover, and their good efficiency which should lead to low phase/compression/IM/harmonic distortion? I guess I'll know for sure once they are built... Thanks Scottmoose for designing the frugel horns! Once I have completed mine I'll post the results back to the main thread. cheers, DB

14th December 2007, 11:31 AM	#5
Scottmoose diyAudio Member Join Date: Mar 2005 Location: UK	I've only ever built a quick tapped horn test-box for an 8in woofer I had lying around -it was never in the main system (no room). But it gave me a good idea of their signiture & it's a good match to most things, providing they have a sense of scale, which a BVR has.

14th December 2007, 02:41 PM	#6
tpakkanen diyAudio Member Join Date: Nov 2004 Location: Finland	At the moment the tapped horn crossover is at 40Hz from my AV-reciever and Bruces are running full range. To my ear this sounds the best compination. The bigger the room is, the better Bruces sound =) I think that Bruces needs some free space behind them. yours, -- Tuomas

14th December 2007, 09:18 PM	#7
broughd diyAudio Member Join Date: Oct 2007	What were the frequency cutoffs of your tapped horns? I would have thought the boxes would have to be quite large to go much under 40hz right? I've got a 12" carbon fiber driver lying around that has an fs of 22hz and QTS of 0.29. I have been trying to figure out what to use it for and I think and a front loaded bass horn seems like a good option, being carbon fibre, cone should be light and strong, good for horn loading, has a big magnet too! At 0.29 the QTS is probably too low for tapped horn isn't it? I tried running it full range and it sounded ok up to 1khz or so but then it beams horribly and seems to have some breakup resonances or something. cheers, DB

14th December 2007, 10:06 PM	#8
Scottmoose diyAudio Member Join Date: Mar 2005 Location: UK	A bit. Fp of mine was 25Hz, which really was pushing the driver too hard. It wasn't supposed to be especially refined though, just a quick 'try it for fun'.

14th December 2007, 10:20 PM	#9
broughd diyAudio Member Join Date: Oct 2007	Fp?

14th December 2007, 10:43 PM	#10
ronc diyAudio Member Join Date: Mar 2003	just a quick 'try it for fun' I use an old RS1354 for tests. Wip up some styro panels with glue and test. Which leads me to another type of Mfg. process. I studied the baffle shape and the front panel of the A166 (currently in SC). Without extensive, and costly, woodworking there was no way to get the suprabaffle/front panel to the desired shape that i saw as being efficent. I was looking for a more teardrop shape of the suprabaffle and a vertical radius, which blended into the suprabaffle, on the front baffle. This sim gave me the least edge diffraction and less direct reflections off the front panel. Now , in the old days when we wanted a shape to test we would build a styro male mold and using as a release medium a cover of Saran wrap then overlay the mold with impregenated (rosin) fiberglass. This is the method used by Mr. Bede on his kit planes and the method i am using on my HY PO trike models for aerodynamic studies. So to achieve the desired shapes on the A166 i will be using the above method. As i have acccess to a CMM the layers will be built up and ground down until the two horns match within a given tolerence. Should be interesting. I just want to bring the A166 up to its total full potential. ron As an added note, i rejected the use of Carbon fiber in this application due to the cost and the need to vacumme form.