I do feel like I have to boost the highs quite a bit with the Alpair 10P Paper Cone 6". The driver is too large to be playing up as high as I would like it to. I think that little 3" might be the ticket. What do you have it crossed at? I think I might want to just let the 10p do midrange duty and the 3" handle up top, but at that point should I just get a full on tweeter like the ribbon someone mentioned to go along with the 10p as the midrange? I'm fine playing with slopes and XO frequencies as this is all active anyway and I have 6 channels of amplification and DSP.
What's funny is I feel like I'm chasing the sound I once had with my Lii Audio L15 driver. That was the thinnest material driver I've ever had for a driver (you could see the color of your skin if you put your fingers behind the driver in the light is was so thin). It rolled off up top but, having an open baffle with zero XO (except to the subwoofer) was amazing!!! The craziest imaging I've ever had but definitely a head in a vice speaker due to the large driver beaming at higher frequencies.
Not sure how old you are, but I’m mid sixties and can’t hear much above 14khz. The little Alpairs easily get to there and sounds fantastic. Contrary to popular wisdom, I let them play pretty much full range, handling most of the vocals through a 250uf cap just to protect them from damaging lows. The natural rolloff begins about 200hz with that driver not in a box. I drive the two GRS in parallel, so 4 ohms through a 9mh inductor. Electrical roll off begins at 70hz first order but because of open baffle, real roll off is mid 100s. Again, these numbers came from trial and error, not theory. I then use an 8 ohm L-pad on the Alpair to tweak the balance of bass and full range. Important to reverse polarity with passive crossover but active shouldn’t have to??? I originally came up with the crossover numbers running the a10p’s, so you might want to try my numbers active with your setup, but I found the 7.3s just sound much sweeter. Can’t really explain that because I love the sound of the a10p in the Frugel horns. To simulate with active, it should be 70hz first order for the grs and 100hz, first order for the Alpairs. For whatever reason, the 10s could be driven to xmax but I’ve never bottomed the 7s. If you try my numbers, let me know what you think of the sound. The way I built my ”boxes” the bottom GRS is in a 7” deep u-frame and the top GRS in a 3 sided u-frame of the same depth. Bass is good and drums sound natural. I have a thin felt surround around the Alpairs for diffraction, but hear little, if any difference. I do, however have 1/2” foam on the back which DID make a difference.
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nwicliff, imaging is fair with the 7.3s. A little better than the 10s. I’ve also built a pair of Decware DNAs with the A10p and the imaging of those is stunning. The Frugel horn XL refuses to image in the same manner although the box width is similar. Same driver, different box, different voodoo I guess.
Hey All,
Been lurking on this thread for a while and finally built my own. Here are some pictures. Nothing I ever do woodworking wise goes to plan but they turned out really nice considering. I had to get a nice dowel jig to make sure everything glued together (and stayed together) so some fun learning experiences.
They sound awesome, except I have too much energy in some of the bass. My ears don't mind some of the lowest frequency, but the part right around 100hz, I feel like the baffle and the thin legs attaching it to the bass might be resonating or something.
The measurements confirm the most energy there. If I turn down the EQ around that area it seems to fix it.
Questions -
1. Bass trap - I am using it on the crossover, but I measured almost no difference with or without. Is the bass trap supposed to reduce the bass?
2. Wings - I messed up and made the wings only about 3" deep. Critical mistake?
3. Gameplan - I'm going to do proper measurements of each driver then see if I can the excess energy in the xover. Good idea?
Thanks
Been lurking on this thread for a while and finally built my own. Here are some pictures. Nothing I ever do woodworking wise goes to plan but they turned out really nice considering. I had to get a nice dowel jig to make sure everything glued together (and stayed together) so some fun learning experiences.
They sound awesome, except I have too much energy in some of the bass. My ears don't mind some of the lowest frequency, but the part right around 100hz, I feel like the baffle and the thin legs attaching it to the bass might be resonating or something.
The measurements confirm the most energy there. If I turn down the EQ around that area it seems to fix it.
Questions -
1. Bass trap - I am using it on the crossover, but I measured almost no difference with or without. Is the bass trap supposed to reduce the bass?
2. Wings - I messed up and made the wings only about 3" deep. Critical mistake?
3. Gameplan - I'm going to do proper measurements of each driver then see if I can the excess energy in the xover. Good idea?
Thanks
The bass trap on this speaker doesn't really do anything in the bass region in spite of it's name. It's there to tame the rising response of the woofer. likely in the 1500 to 2300 hz range. It's been too long to remember exactly where but that's the general frequency region.
The 12" Peerless didn't need it as much but some used it anyway. The 15" GRS does need it. It seems to get a smoother sounding midrange when installed.
The 12" Peerless didn't need it as much but some used it anyway. The 15" GRS does need it. It seems to get a smoother sounding midrange when installed.
As Barry says, the woofer trap is for the top end of the woofer, not really bass notes. The GRS has some trouble at the top of its range and the trap cleans it up. The Peerless is better behaved and can do without it. As you are using the GRS, listen to the midrange with and without the trap.
As XRX says, play with the level of the tweeter, you should be able to achieve a correct tonal balance. Thanks for showing us your build!
As XRX says, play with the level of the tweeter, you should be able to achieve a correct tonal balance. Thanks for showing us your build!
They are very nicely built speakers.
You'd think more wing would increase bass but the intricacies of open baffle wing size and shaping is above my pay grade. But before doing too much crossover tweaking it'd be interesting to play with some cardboard and see what a bit more wing would do. Changes in open baffle speakers can be quite entertaining.
And please report back with your findings.
You'd think more wing would increase bass but the intricacies of open baffle wing size and shaping is above my pay grade. But before doing too much crossover tweaking it'd be interesting to play with some cardboard and see what a bit more wing would do. Changes in open baffle speakers can be quite entertaining.
And please report back with your findings.
Ok, thanks for the advice, I will these this weekend.
Right now the speakers sound GREAT when a song doesn't have a ton of bass that's hitting in that 100hz region.
A perfect example of how good they sound is on a song like Chocolate Trip Drip by Tool. I'm not a huge Tool fan, and you might not be either, but this song is mostly drums and it sounds incredible on these speakers - Chocolate Trip Drip (youtube)
Right now the speakers sound GREAT when a song doesn't have a ton of bass that's hitting in that 100hz region.
A perfect example of how good they sound is on a song like Chocolate Trip Drip by Tool. I'm not a huge Tool fan, and you might not be either, but this song is mostly drums and it sounds incredible on these speakers - Chocolate Trip Drip (youtube)
Not really, just a bit of imagination and geometry.
Sound is round' in that you can draw 'rings' on a baffle drawing and as they get larger than the baffle they will fold around the sides to find the approximate side wing depth and for a more complete view, do this from its top since the wave is actually spherical as it resonates from compression/forward to rarefaction/backward @ ~13543"/34400 cm/sec.. The latter also shows how big a corner round-over/triangular approximation must be.
Of course it's not 100% accurate, but IME well within our somewhat limited hearing acuity except for maybe young folks in general and females in particular WRT treble response that tends to be 'sheared'/diffracted off sharp corners.
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Something I forgot that makes it a bit more accurate is that panels have 'pipe end corrections' too, so the circle can extend on the sides a bit before folding back with the basic one = 0.613*radius, so add this to the 20" to find its effective frequency, though from dim memory, seems like someone mentioned 'Edge' factors in some of this; regardless a good program to start with for OB, haven't checked Hornresp's (HR) Wizard, but imagine it does.
I want to ask a dumb question. I am intrigued by OB speakers but before I dive into buying all the material and then building them, couldn’t I simply take an old pair of speakers and remove the top and back of the case? Maybe cut back the sides to open it up more? Wouldn’t I get a similar result? Or even use the old hardware and mount them to a new panel?
Well, I think you wouldn't get similar result.
You may or may not get the openness and liveliness, but almost certainly you would miss the bass.
The use of the old driver in a new (open) baffle could disappoint you too - for decent bass you do need big(gish) woofer, at least 12" - the bigger the better. The xo is the second thing.
But - you can collect a lot of experience and know how (and how don't) going this way.
You may or may not get the openness and liveliness, but almost certainly you would miss the bass.
The use of the old driver in a new (open) baffle could disappoint you too - for decent bass you do need big(gish) woofer, at least 12" - the bigger the better. The xo is the second thing.
But - you can collect a lot of experience and know how (and how don't) going this way.
Thanks for the useful feedback. One last question if I may. I was looking at the Monacor Katana kit and I think it does not come any large speakers (<10 in). And I don’t think they have a woofer either. And they seem popular with good reviews. Is the woofer important to an OB speaker?
Thanks again.
Thanks again.