Hi guys
I have been offered a couple of SB12PAC25 drivers:
4" SB12PAC25-4 :: SB Acoustics
I would like to use them with a reasonably priced tweeter in a 2-way. I haven't come across much info on these drivers. Thoughts?
I have been offered a couple of SB12PAC25 drivers:
4" SB12PAC25-4 :: SB Acoustics
I would like to use them with a reasonably priced tweeter in a 2-way. I haven't come across much info on these drivers. Thoughts?
Hi,
There is a kit here:
SB Acoustics :: Micro Kit
The SB19ST tweeter is cheap and good.
Crossover should be OK - you can find it under "Schematic" link.
S
There is a kit here:
SB Acoustics :: Micro Kit
The SB19ST tweeter is cheap and good.
Crossover should be OK - you can find it under "Schematic" link.
S
They would certainly benefit from a sub. They will be used on a PC. The speakers they are replacing are 6.5" drivers good for 54Hz but quite a large box. These are very compact.
Quite a nice driver and Troels used them in a TV speaker.
myTV
I bought a pair to carve up as a small PR but were too good. I did a pair for near field use above my workbench. The box has a removable baffle so I can test small drivers. Used the NE19VTS-04 tweeter crossed over at 3800Hz. The breakup above 10kHz is better than most metal cones and the crossover drops it far enough (around 18dB) that it's not an issue, plus it's off axis listening. The NE19VTS-04 works well with them but needs really small screws which can be hard to find in black. The SB26STCN-C000-4 could be another choice as used in JB's Soprano.
The combination worked better than any FR drivers I tested with more body, slam and top end. The bottom end was enough for near field use and the small listening area.
The shallow box I used was Vb=2.6 litres, Fb=78Hz, F3=72Hz, F6=65Hz but can go up to around 4 litres for a lower F3 but xmax increases.
BTW... I didn't bother to rebate the SB12PAC as not worth the effort but the tweeter is rebated. I could have gone for tighter TM spacer but kept it wider so a larger tweeter could fit if the NE19 didn't work.
myTV
I bought a pair to carve up as a small PR but were too good. I did a pair for near field use above my workbench. The box has a removable baffle so I can test small drivers. Used the NE19VTS-04 tweeter crossed over at 3800Hz. The breakup above 10kHz is better than most metal cones and the crossover drops it far enough (around 18dB) that it's not an issue, plus it's off axis listening. The NE19VTS-04 works well with them but needs really small screws which can be hard to find in black. The SB26STCN-C000-4 could be another choice as used in JB's Soprano.
The combination worked better than any FR drivers I tested with more body, slam and top end. The bottom end was enough for near field use and the small listening area.
The shallow box I used was Vb=2.6 litres, Fb=78Hz, F3=72Hz, F6=65Hz but can go up to around 4 litres for a lower F3 but xmax increases.
BTW... I didn't bother to rebate the SB12PAC as not worth the effort but the tweeter is rebated. I could have gone for tighter TM spacer but kept it wider so a larger tweeter could fit if the NE19 didn't work.
Attachments
The crossover I designed was based around the components I had in hand. I tried my usual series xo first but not suitable, so parallel it is. Sounds very good with a nice overall balance but I would say that wouldn't I.
These are used nearfield at my work bench.
These are used nearfield at my work bench.
Attachments
SB micro-kit
Hi Rabbitz and Everybody,
I built a SB Acoustics micro-kit, which is close to Rabbitz design except :
* SB12PAC is BR loaded
* Tweeter is SB19ST
* Hi-Pass is 3rd-order
At first listening, these tiny speakers are impressive : very good tonal balance, a lot of details, dynamic and lively and not shouting.
The imaging (and specially depth) is just OK, not great
After listening with more attention, a flaw can appear : treble is a bit "sad", or should I say shy ? Not a tonal balance problem, which remains crispy, but lacking of engagement. Too much attenuation ?
In fact I can't find the SB19ST character mentioned in different reviews.
Analyzing SB12PAC FR, a big and wide ringing appears (7k --> 17k, up to 12dB). Even if it is attenuated by LP, I guess it can affect the LP transfer function.
Here comes the idea of adding a notch to tame the SB12 ringing.
I first try a series L + R + C, paralleled with the speaker. Values are :0.22mH + 8.2R + 1uF
Improvement is obvious : the treble is kind of "free'd", more tuneful and delicate. Now the character of SB19 appears.
Imaging improves a bit.
But no free lunch : now, it seems to appear a small "missing" between the two drivers.
Next experiment will be to increase a bit LP cut-off frequency.
Will let you know.
Has anybody (and specially Rabbitz) experienced such behavior of SB12 PAC ?
I would be happy to share informations about our experiments / solutions.
Regards
Pascal
Hi Rabbitz and Everybody,
I built a SB Acoustics micro-kit, which is close to Rabbitz design except :
* SB12PAC is BR loaded
* Tweeter is SB19ST
* Hi-Pass is 3rd-order
At first listening, these tiny speakers are impressive : very good tonal balance, a lot of details, dynamic and lively and not shouting.
The imaging (and specially depth) is just OK, not great
After listening with more attention, a flaw can appear : treble is a bit "sad", or should I say shy ? Not a tonal balance problem, which remains crispy, but lacking of engagement. Too much attenuation ?
In fact I can't find the SB19ST character mentioned in different reviews.
Analyzing SB12PAC FR, a big and wide ringing appears (7k --> 17k, up to 12dB). Even if it is attenuated by LP, I guess it can affect the LP transfer function.
Here comes the idea of adding a notch to tame the SB12 ringing.
I first try a series L + R + C, paralleled with the speaker. Values are :0.22mH + 8.2R + 1uF
Improvement is obvious : the treble is kind of "free'd", more tuneful and delicate. Now the character of SB19 appears.
Imaging improves a bit.
But no free lunch : now, it seems to appear a small "missing" between the two drivers.
Next experiment will be to increase a bit LP cut-off frequency.
Will let you know.
Has anybody (and specially Rabbitz) experienced such behavior of SB12 PAC ?
I would be happy to share informations about our experiments / solutions.
Regards
Pascal
I didn't notice anything odd with the behaviour of the SB12PAC25-4 as it worked well straight from the design to build. Both my design and Troel's version have very simple crossovers and mine pushes the SB12PAC a bit higher so would notice any nasties in the higher frequencies if they were there. Mine uses the natural driver roll off with the filter to drop it faster to give it the final acoustic slope. This was done to have a high xo point (3800hz) to remove any stress on the tweeter as it used a 2nd order filter. I never listened to the woofer only with LP filter plus I only hear to 10kHz which may have a bearing.
For reference here is Troel's xo. http://www.troelsgravesen.dk/panasonic/panasonic--203.jpg
The article link is in post #6 and he gave no indication of anything nasty.
You may want to check the drivers polarity as the Micro kit has them both wired +ve polarity. What you are describing sounds like a dip in the crossover area or a phase issue.... sort of a hole in the middle.
You could try Troel's woofer xo components and/or dropping the tweeter back to 2nd order (try both polarities) to get a wider overlap between the drivers.
For reference here is Troel's xo. http://www.troelsgravesen.dk/panasonic/panasonic--203.jpg
The article link is in post #6 and he gave no indication of anything nasty.
You may want to check the drivers polarity as the Micro kit has them both wired +ve polarity. What you are describing sounds like a dip in the crossover area or a phase issue.... sort of a hole in the middle.
You could try Troel's woofer xo components and/or dropping the tweeter back to 2nd order (try both polarities) to get a wider overlap between the drivers.
Pascal
Here's a quick mod you can try using existing components to give 2nd order on the tweeter and have a better overlap between drivers.
C2 remove 10uF and add link, C1 replace 3.3uF with 10uF, reverse tweeter polarity to -ve polarity.
This should remove any dip at the xo point and drops the xo point down to around 3100Hz.
Here's a quick mod you can try using existing components to give 2nd order on the tweeter and have a better overlap between drivers.
C2 remove 10uF and add link, C1 replace 3.3uF with 10uF, reverse tweeter polarity to -ve polarity.
This should remove any dip at the xo point and drops the xo point down to around 3100Hz.
Hi Rabbitz,
Many thanks for your suggestions, I sure will try.
I made another try, by changing the lowpass inductor from 0,68mH (as indicated in kit manual) to 0,54mh, this fills the "lack" between the speakers, without affecting their already shown qualities.
But I am really interrested in the second order hipass you propose, to "symetrize" cut off slopes, I guess that will improve imaging.
All in all, these really tiny speakers are really very good sounding, but the pleasure of diy is also in tweaking, specially with the help and suggestions of diy mates.
Will let you know about the progresse of my experimentations...
Many thanks for your suggestions, I sure will try.
I made another try, by changing the lowpass inductor from 0,68mH (as indicated in kit manual) to 0,54mh, this fills the "lack" between the speakers, without affecting their already shown qualities.
But I am really interrested in the second order hipass you propose, to "symetrize" cut off slopes, I guess that will improve imaging.
All in all, these really tiny speakers are really very good sounding, but the pleasure of diy is also in tweaking, specially with the help and suggestions of diy mates.
Will let you know about the progresse of my experimentations...
Hi Rabbitz and everybody,
I have try what you suggested in your post, and I tried a lot of adjustments without finding a one that was really satisfying ...
...then I became aware of one thing, a beginner's fail : the positioning of the speaker.
As bookshelf speakers, they where installed on a shelf (!)
Too high a shelf : approx. 1.5m from ground, tweeter level 15cm higher
So I quickly made an appropriate stand, placing tweeter a ear level, and then everything changed.
No transition miss, no crossover tweak needed (I returned to SB design), and a very pleasing speaker to listen to. Really surprising for such a tiny thing, and getting even better as running in.
I am really sorry for wasting your time with my questions and a bit ashamed having been tricked by my impatience.
I have try what you suggested in your post, and I tried a lot of adjustments without finding a one that was really satisfying ...
...then I became aware of one thing, a beginner's fail : the positioning of the speaker.
As bookshelf speakers, they where installed on a shelf (!)
Too high a shelf : approx. 1.5m from ground, tweeter level 15cm higher
So I quickly made an appropriate stand, placing tweeter a ear level, and then everything changed.
No transition miss, no crossover tweak needed (I returned to SB design), and a very pleasing speaker to listen to. Really surprising for such a tiny thing, and getting even better as running in.
I am really sorry for wasting your time with my questions and a bit ashamed having been tricked by my impatience.
Glad it worked out and you have found that speaker location is very important.
Generally, tweeters should be around ear height and distances to boundaries should be different in each direction (speaker to back wall, to floor, to corner) and should not be a direct multiple of each other. Moving speakers around can find a sweet spot.
No wasted time at all but would have been a waste if the outcome was not posted.
Generally, tweeters should be around ear height and distances to boundaries should be different in each direction (speaker to back wall, to floor, to corner) and should not be a direct multiple of each other. Moving speakers around can find a sweet spot.
No wasted time at all but would have been a waste if the outcome was not posted.
@Gropascal - mate - Location, Location, Location!!! There is number of room acoustic tweaks you can do before doing crossovers exercises!!! You found it the hard way but at least you have a satisfying result. The amplifier, source and wiring will affect the sound as well. Cheers and happy listening!
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