BetsyK in OB - Page 2

nesha · 20th April 2012, 03:53 PM

Just TQWT. I had them measured, and there is broad peek around 3,4 kHz, but I was nicely surprised not to hear agresive top end. I had chance to hear (and measure) them without any baffle (suspended ) , and then BetsyK sounded agresive. I also didn't like them in 60l test bass-reflex box, again thin and on agresive side. But this tqwt was a surprise, bass, a lot of it. Sometimes jest right, sometimes too much, sometimes I would like a more warmth, it really depends on recording.
Have you consider bass helper (or two)? It's OB what I really wanted to experiment with,but I can't have them a 1m away from the wall

cpmiller · 20th April 2012, 06:09 PM

As a matter of fact I am going to experiment with adding 15" Eminence Alpha. My room is only 14' X 11' but I can manage to place the OB's 1m from the wall. I'd like to be able to pull this off with passive XO but the sensitivity of the BetsyK's is so good I'm not sure if the Alpha will work out.

I'm impressed what MLTL and TQWT designs can do for bass with full range for the size of cabinet. And they sound very good. Experimenting with BetseyK is my first experience with OB.

cpmiller · 26th April 2012, 10:54 PM

As further experimentation I've added the Eminence Alpha-15A subwoofer to the
BetsyK attached to the 2'X4' Home Depot MDF baffle (geez, I am cheap arent' I). The subwoofer is passively connected via an inexpensive PE 80Hz low pass.

The results are interesting when measuring with my RS SPl meter (also cheap) and using pink noise audio tracks. It seems to me the transition around 200Hz
is the baffle step. I am planning to attempt a 3 dB baffle step correction to the BetsyK path and see if that helps equalize the low bass as a trade off of a few dB of sensitivity. If that works it's a useful feature of using the higher sensitivity of the BetsyK vs. the standard Betsy for this application. I do not know how the phase alignment will do with this kind of set up but I plan to get out my o-scope with a signal source and look at it. Simulating this is beyond my experience so far so everything I am doing is empirical using crude measurement techniques.

BetseyK_OB
dB Hz
-5 32
-3 40
-2 50
-2 62
-2.5 80
-3 100
-3 125
-2.5 160
-1.5 200
-0.8 250
-0.5 315
-0.5 400
-0.5 500
0 630
0 800
0 1000

pjanda1 · 27th April 2012, 12:56 AM

Think about your baffle width. It is going to limit how low you can take the Betsy/K. Unless you drive the Qts up very high (which probably isn't a good idea for higher frequencies), you aren't going to have much luck using it to fill in the mid-bass. However, the whole point of the super high-Qts Alpha 15 is they way it meshes with the narrower baffle. You need to cross it over higher. It would also be informative to measure each driver separately.

Paul
Wild Burro Audio Labs - DIY Full Range Speakers

cpmiller · 27th April 2012, 01:42 AM

Paul, thanks for you feedback.

I will measure output from each driver separately. If forgot to mention this time I measured from my listening position due to the difficulty of measuring OB with sub at 1m distance. Still by listening position is relatively near field at 8 feet.

I suppose I was lazy and didn't pick a smart baffle width. I was just minimizing the cuts I had to make and planning to easily accomadate the subwoofer.

What surprised me was to see the output relatively flat from below the 80 Hz cut off transitioning to the BetsyK. I've been wondering if that's because the relatively high 1.6 Ohm inductor resistance of the cheap low pass is knocking down the sensitivity of the Alpha 15A some.

I have no filter in front of the BetsyK at this point, which why I chose the 80Hz cut off. If I raise the XO to closer to the baffle step point (around 200Hz I think) won't I need to put a high pass in front of the BetsyK then or are you suggesting that moving up the XO on the Alpha will fill in the 3dB drop below 300Hz?

Thanks, Chris

pjanda1 · 27th April 2012, 03:03 AM

Chris:

Careful with how you use "baffle step". You're really getting dipole cancellation below 200 hz or so. I do think moving the XO up will help fill in that hole. With such simple means, whatever you do isn't going to be perfect. I'd rather see you work to push the woofer up a bit rather than the fullranger down. Another option before you try a BSC like filter would be to add some wings behind the BetsyK. Pink foam and cardboard are easy to experiment with. You don't want wings beside the Alpha, or you'll probably get a hump.

Paul
Wild Burro Audio Labs - DIY Full Range Speakers

cpmiller · 27th April 2012, 10:14 PM

Paul, this weekend I will measure both drivers and see what the data looks like. I was also thinking about adding wings by trying some pink rigid insulation or similar. I had not considered that the data could be showing bipolar cancellation.

cpmiller · 18th September 2012, 02:02 AM

It's been quite a long time since I posted an update. Where am I in my exploration with my Betsy-K's? Well I'm still listening to them. I've ended up with subwoofers (Eminence Deltalite 2515's through a low-pass) but the Betsy's running without a high-pass. Still using the MDF baffles. This weekend I will audition for a long time friend who's also an audiophile. No idea what he'll think but this has been quite an adventure.

e_fortier · 11th December 2012, 05:22 AM

Quote:

Originally Posted by cpmiller

It's been quite a long time since I posted an update. Where am I in my exploration with my Betsy-K's? Well I'm still listening to them. I've ended up with subwoofers (Eminence Deltalite 2515's through a low-pass) but the Betsy's running without a high-pass. Still using the MDF baffles. This weekend I will audition for a long time friend who's also an audiophile. No idea what he'll think but this has been quite an adventure.

Thanks for sharing,

I also have a pair of Betsy-K that I will soon use with some Eminence Alpha 15A in a H frame. Good to know this driver sounds good in OB.

Eric

cpmiller · 11th December 2012, 02:29 PM

Hi Eric,
I've been continuing along an evolutionary path with the Betsy-K. Since using the Alpha 15A I migrated to the Delta 2515 using Troels Gravsen's subwoofer crossover but w/o attenuation (OBL11). I'm also experimenting with the addition of a super-tweeter. This system is sounding very nice and is quite sensitive (around 96-97dB/W) allowing me to even try a 2-3 W amp in a smallish room. I still have the 15A's that I'm not using if you would be interested in them at a good price.

I look forward to hear how your project goes.

Chris

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20th April 2012, 03:53 PM	#11
nesha diyAudio Member Join Date: Jan 2007 Location: Beograd, Serbia	Just TQWT. I had them measured, and there is broad peek around 3,4 kHz, but I was nicely surprised not to hear agresive top end. I had chance to hear (and measure) them without any baffle (suspended ) , and then BetsyK sounded agresive. I also didn't like them in 60l test bass-reflex box, again thin and on agresive side. But this tqwt was a surprise, bass, a lot of it. Sometimes jest right, sometimes too much, sometimes I would like a more warmth, it really depends on recording. Have you consider bass helper (or two)? It's OB what I really wanted to experiment with,but I can't have them a 1m away from the wall

20th April 2012, 06:09 PM	#12
cpmiller diyAudio Member Join Date: Jul 2009	As a matter of fact I am going to experiment with adding 15" Eminence Alpha. My room is only 14' X 11' but I can manage to place the OB's 1m from the wall. I'd like to be able to pull this off with passive XO but the sensitivity of the BetsyK's is so good I'm not sure if the Alpha will work out. I'm impressed what MLTL and TQWT designs can do for bass with full range for the size of cabinet. And they sound very good. Experimenting with BetseyK is my first experience with OB.

26th April 2012, 10:54 PM	#13
cpmiller diyAudio Member Join Date: Jul 2009	As further experimentation I've added the Eminence Alpha-15A subwoofer to the BetsyK attached to the 2'X4' Home Depot MDF baffle (geez, I am cheap arent' I). The subwoofer is passively connected via an inexpensive PE 80Hz low pass. The results are interesting when measuring with my RS SPl meter (also cheap) and using pink noise audio tracks. It seems to me the transition around 200Hz is the baffle step. I am planning to attempt a 3 dB baffle step correction to the BetsyK path and see if that helps equalize the low bass as a trade off of a few dB of sensitivity. If that works it's a useful feature of using the higher sensitivity of the BetsyK vs. the standard Betsy for this application. I do not know how the phase alignment will do with this kind of set up but I plan to get out my o-scope with a signal source and look at it. Simulating this is beyond my experience so far so everything I am doing is empirical using crude measurement techniques. BetseyK_OB dB Hz -5 32 -3 40 -2 50 -2 62 -2.5 80 -3 100 -3 125 -2.5 160 -1.5 200 -0.8 250 -0.5 315 -0.5 400 -0.5 500 0 630 0 800 0 1000

27th April 2012, 12:56 AM	#14
pjanda1 diyAudio Member Join Date: Jan 2005 Location: Boulder, CO	Think about your baffle width. It is going to limit how low you can take the Betsy/K. Unless you drive the Qts up very high (which probably isn't a good idea for higher frequencies), you aren't going to have much luck using it to fill in the mid-bass. However, the whole point of the super high-Qts Alpha 15 is they way it meshes with the narrower baffle. You need to cross it over higher. It would also be informative to measure each driver separately. Paul Wild Burro Audio Labs - DIY Full Range Speakers

27th April 2012, 01:42 AM	#15
cpmiller diyAudio Member Join Date: Jul 2009	Paul, thanks for you feedback. I will measure output from each driver separately. If forgot to mention this time I measured from my listening position due to the difficulty of measuring OB with sub at 1m distance. Still by listening position is relatively near field at 8 feet. I suppose I was lazy and didn't pick a smart baffle width. I was just minimizing the cuts I had to make and planning to easily accomadate the subwoofer. What surprised me was to see the output relatively flat from below the 80 Hz cut off transitioning to the BetsyK. I've been wondering if that's because the relatively high 1.6 Ohm inductor resistance of the cheap low pass is knocking down the sensitivity of the Alpha 15A some. I have no filter in front of the BetsyK at this point, which why I chose the 80Hz cut off. If I raise the XO to closer to the baffle step point (around 200Hz I think) won't I need to put a high pass in front of the BetsyK then or are you suggesting that moving up the XO on the Alpha will fill in the 3dB drop below 300Hz? Thanks, Chris

27th April 2012, 03:03 AM	#16
pjanda1 diyAudio Member Join Date: Jan 2005 Location: Boulder, CO	Chris: Careful with how you use "baffle step". You're really getting dipole cancellation below 200 hz or so. I do think moving the XO up will help fill in that hole. With such simple means, whatever you do isn't going to be perfect. I'd rather see you work to push the woofer up a bit rather than the fullranger down. Another option before you try a BSC like filter would be to add some wings behind the BetsyK. Pink foam and cardboard are easy to experiment with. You don't want wings beside the Alpha, or you'll probably get a hump. Paul Wild Burro Audio Labs - DIY Full Range Speakers

27th April 2012, 10:14 PM	#17
cpmiller diyAudio Member Join Date: Jul 2009	Paul, this weekend I will measure both drivers and see what the data looks like. I was also thinking about adding wings by trying some pink rigid insulation or similar. I had not considered that the data could be showing bipolar cancellation.

18th September 2012, 02:02 AM	#18
cpmiller diyAudio Member Join Date: Jul 2009	It's been quite a long time since I posted an update. Where am I in my exploration with my Betsy-K's? Well I'm still listening to them. I've ended up with subwoofers (Eminence Deltalite 2515's through a low-pass) but the Betsy's running without a high-pass. Still using the MDF baffles. This weekend I will audition for a long time friend who's also an audiophile. No idea what he'll think but this has been quite an adventure.

11th December 2012, 02:29 PM	#20
cpmiller diyAudio Member Join Date: Jul 2009	Hi Eric, I've been continuing along an evolutionary path with the Betsy-K. Since using the Alpha 15A I migrated to the Delta 2515 using Troels Gravsen's subwoofer crossover but w/o attenuation (OBL11). I'm also experimenting with the addition of a super-tweeter. This system is sounding very nice and is quite sensitive (around 96-97dB/W) allowing me to even try a 2-3 W amp in a smallish room. I still have the 15A's that I'm not using if you would be interested in them at a good price. I look forward to hear how your project goes. Chris