Fired up my latest project – Alpair 7.3’s on small OB’s over Goldwood GW-1858’s in H-frames. My initial impression is that I am underwhelmed. Tomorrow, I will try my T7-A7 TL’s as tops.
Design decisions will dictate the results. For the same reasons that I don’t do big double BVR’s and back-horns, I won’t do big OB’s. I have no place to put speakers much bigger than the 43”x12” MLTL’s. If I built one commercially, I would have no reasonable way to ship it. Anyway, a large OB is out of the question. The OB’s in the picture are 20” tall, 10” wide at the base and 5” wide at the top. These are strictly test mules cut out of scrap plywood. If I decide to go with them, I will do them out of walnut lumber double thick at the edges. The H-baffles are already done in walnut veneer.
The cross-over is done in Foobar2000 on a laptop. There is a basic XO plug-in that works pretty well. It is a 3-way XO at any frequency and any order. Cross-over points do not have to be symmetric. 31- band graphic EQ is also available within the player. (I have a miniDSP on the way, but as well a Foobar2000 is working, I may have wasted $150.) The output goes via USB to an M-Audio Ultra Track which splits to output into four channels and converts to analog. The treble goes to a Topping TP-60 and on to the Alpair 7.3’s. The bass goes to a Dayton DTA-100 and on to the GW-1858’s.
Because of their size, the OB’s have an acoustic roll-off at ~300Hz. I high-passed them at 100Hz 4th order just to reduce excursion. I could probably cut them higher and will play with that if I go with the OB’s. The H-baffles are low passed at 125Hz 3rd order. The cross-over appears to be working. The SPL is pretty flat across as measured with an SPL meter. (Since my laptop, my only computer, is running the DSP, I can’t use it to run my measurement suite!
)
Basically, the system sounds pretty good. On the pop stuff I test with (Alison Krauss, Diana Krall, Fleetwood Mac, Pink Floyd and a bunch of other stuff), I have no problems. The bass is just a bit tubby (I’d say slow it I didn’t know that bass isn’t slow, the mid’s are). With classical music, there is a big problem. The low cello’s are hollow and muddy. Bass is fine, treble is great. Upper bass is screwed up. Since this range is handled by the H-frames, the problem probably resides there. I will have to investigate. I may not be able to run the H-frames that high. If so, the OB’s are out and the TL’s are in. I can run TL’s at least as deep as 80Hz and still reduce the excursion to reasonable limits. At 80dB@8’ with pretty strong kick drum, neither driver moves visibly. Since both amps are sitting at 10 o’clock, ear bleed SPL is assured.
More tests tomorrow.
Bob
Design decisions will dictate the results. For the same reasons that I don’t do big double BVR’s and back-horns, I won’t do big OB’s. I have no place to put speakers much bigger than the 43”x12” MLTL’s. If I built one commercially, I would have no reasonable way to ship it. Anyway, a large OB is out of the question. The OB’s in the picture are 20” tall, 10” wide at the base and 5” wide at the top. These are strictly test mules cut out of scrap plywood. If I decide to go with them, I will do them out of walnut lumber double thick at the edges. The H-baffles are already done in walnut veneer.
The cross-over is done in Foobar2000 on a laptop. There is a basic XO plug-in that works pretty well. It is a 3-way XO at any frequency and any order. Cross-over points do not have to be symmetric. 31- band graphic EQ is also available within the player. (I have a miniDSP on the way, but as well a Foobar2000 is working, I may have wasted $150.) The output goes via USB to an M-Audio Ultra Track which splits to output into four channels and converts to analog. The treble goes to a Topping TP-60 and on to the Alpair 7.3’s. The bass goes to a Dayton DTA-100 and on to the GW-1858’s.
Because of their size, the OB’s have an acoustic roll-off at ~300Hz. I high-passed them at 100Hz 4th order just to reduce excursion. I could probably cut them higher and will play with that if I go with the OB’s. The H-baffles are low passed at 125Hz 3rd order. The cross-over appears to be working. The SPL is pretty flat across as measured with an SPL meter. (Since my laptop, my only computer, is running the DSP, I can’t use it to run my measurement suite!
)
Basically, the system sounds pretty good. On the pop stuff I test with (Alison Krauss, Diana Krall, Fleetwood Mac, Pink Floyd and a bunch of other stuff), I have no problems. The bass is just a bit tubby (I’d say slow it I didn’t know that bass isn’t slow, the mid’s are). With classical music, there is a big problem. The low cello’s are hollow and muddy. Bass is fine, treble is great. Upper bass is screwed up. Since this range is handled by the H-frames, the problem probably resides there. I will have to investigate. I may not be able to run the H-frames that high. If so, the OB’s are out and the TL’s are in. I can run TL’s at least as deep as 80Hz and still reduce the excursion to reasonable limits. At 80dB@8’ with pretty strong kick drum, neither driver moves visibly. Since both amps are sitting at 10 o’clock, ear bleed SPL is assured.
More tests tomorrow.
Bob
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>>> The H-baffles are already done in walnut veneer.
They look great.
I have Alpha 15s in H frames and think they begin contaminating the overall sound if crossed over too high (as in over 90hz). These things are meant to play bass ONLY. If the 15 inch drivers become audibly intrusive than the 18 inch Goldwoods probably even more so. I'd keep them below 70hz (estimated of course... i've never heard the Goldwoods).
When i built the H frames i knew i would not be happy with a small OB on top like yours because they would not go low enough to allow a low enough crossover. Mated to BIBs i was able to blend the H frames well between 50 and 70hz with excellent results. When i made my OB I found the Eminence Beta 12lta went to around 150hz on a 20 x 20 inch baffle and was able to fiddle with the variable crossover on the sub amp to get a good blend. I listened to them for hours today and they just make me happy with their great, full, relaxed sound. I love them.
As neat as the Alpair's are... not sure i would enjoy them in the configuration you are listening to right now. I had the TB 1808s on OB and they just barely blended with the H frames for good results to my ears. I will be doing something else with those drivers in the future.
One of the great advantages of H frames (if you like their sound and they fit your room) is they serve as speaker stands too. I hope you try other bookshelf type designs to sit atop your lovely H frames... personally, i think many boxed speakers tailored to the H frames dimensions would work excellently!
Don't give up on them and please let us know your progress.
Thanks!
Zilla
They look great.
I have Alpha 15s in H frames and think they begin contaminating the overall sound if crossed over too high (as in over 90hz). These things are meant to play bass ONLY. If the 15 inch drivers become audibly intrusive than the 18 inch Goldwoods probably even more so. I'd keep them below 70hz (estimated of course... i've never heard the Goldwoods).
When i built the H frames i knew i would not be happy with a small OB on top like yours because they would not go low enough to allow a low enough crossover. Mated to BIBs i was able to blend the H frames well between 50 and 70hz with excellent results. When i made my OB I found the Eminence Beta 12lta went to around 150hz on a 20 x 20 inch baffle and was able to fiddle with the variable crossover on the sub amp to get a good blend. I listened to them for hours today and they just make me happy with their great, full, relaxed sound. I love them.
As neat as the Alpair's are... not sure i would enjoy them in the configuration you are listening to right now. I had the TB 1808s on OB and they just barely blended with the H frames for good results to my ears. I will be doing something else with those drivers in the future.
One of the great advantages of H frames (if you like their sound and they fit your room) is they serve as speaker stands too. I hope you try other bookshelf type designs to sit atop your lovely H frames... personally, i think many boxed speakers tailored to the H frames dimensions would work excellently!
Don't give up on them and please let us know your progress.
Thanks!
Zilla
I am thinking that the problem is cavity resonance. The range I am hearing the problem in is somewhere 60-100Hz. The Goldwoods in a different cabinet should be good to 200Hz or so.
Given the same rough volume, if I can't make the H-frames work with the small TL's, the Dayton RSS315HF will give both deeper bass and go up to 500Hz. I do have high hopes for the H-frames and the TL's. though.
Bob
Given the same rough volume, if I can't make the H-frames work with the small TL's, the Dayton RSS315HF will give both deeper bass and go up to 500Hz. I do have high hopes for the H-frames and the TL's. though.
Bob
Well, if the bass is fine and treble is great, then you should focus on in between.
I think it is impossible to have good mids with such a small driver on open baffle.
For full cello and probably piano and voices, you will need a 8" or 12" with a qts around 0.7.
And also, you are trying to blend a driver with a 3gr membrane with one that is over 100gr.
Since you already have the 3 way capability, I would add a light papercone 12" in the middle on OB with shallow wings around it.
I think it is impossible to have good mids with such a small driver on open baffle.
For full cello and probably piano and voices, you will need a 8" or 12" with a qts around 0.7.
And also, you are trying to blend a driver with a 3gr membrane with one that is over 100gr.
Since you already have the 3 way capability, I would add a light papercone 12" in the middle on OB with shallow wings around it.
Did you design them with the MJK worksheet? Including the room situation? I'm not sure those H frames are far enough from the front wall. As mentioned by others, the size difference between the drivers is an issue too. Makes it difficult to find a good Xover frequency.
Bob
I would try a solid baffle for both units,The H frames are great
but I could never get them to blend with other drivers,
something strange in the 200Hz to 300Hz range for sure.
I used a pair of CSS el70 with Eminence Alpha 15a for a while on
single flat baffle 20 wide 40 high with the EL70 off set to one side
and it actually sounded very good.
I will tell you that size matters greatly when it come to OB
driver and baffle I tend to like 8 inch on up to 15 inch full range
units better than the smaller drivers personally.
I would try a solid baffle for both units,The H frames are great
but I could never get them to blend with other drivers,
something strange in the 200Hz to 300Hz range for sure.
I used a pair of CSS el70 with Eminence Alpha 15a for a while on
single flat baffle 20 wide 40 high with the EL70 off set to one side
and it actually sounded very good.
I will tell you that size matters greatly when it come to OB
driver and baffle I tend to like 8 inch on up to 15 inch full range
units better than the smaller drivers personally.
As I said in my OP. large single panel OB's are not allowed.
I am in the midst of testing the small TL's with the H-frames. I have confirmed that my problem is a cavity resonance around 100Hz. Using a 4th order Chebyshev low-pass on the H-frames and 4th order Butterworth at 100 on the TL's.The cross-over is smack-dab in the middle of a room mode. Bass into the hole, treble out. Seamless. I still need to play a while. More later.
Bob
Using a small TL on an H-frame bass unit is only as good as a good musical subwoofer mated with a bookshelf speaker 
with none of the boxless spacious sound of a full spectrum OB speaker.
I would hate to see you throwing out the baby with the bath, if you dismiss the wide ranger on OB atop the h-frame, so early !! Martin has pioneered this concept with excellent results from so many including myself. The lifelike transient response of the mid-bass and bass frequencies ( ie upwards from 40Hz) produced by an H-frame rivals even dedicated high output midbass modules like the Hsu MBM unit. I am yet to hear the very expensive Rythmiks.
Going by Martin's sheets you simply need some deep "wings", maybe 8-10", on your narrow OB on top, to make it fly !! Or even better and with the same dimensions, do a 2 way OB on top with an 8-10" midrange and tweeter...like the Basszilla.
I had started with 15" GW in H-frame and then switched to the ubiquitous Eminence 15 alpha, giving a harder punch.
with none of the boxless spacious sound of a full spectrum OB speaker.I would hate to see you throwing out the baby with the bath, if you dismiss the wide ranger on OB atop the h-frame, so early
!! Martin has pioneered this concept with excellent results from so many including myself. The lifelike transient response of the mid-bass and bass frequencies ( ie upwards from 40Hz) produced by an H-frame rivals even dedicated high output midbass modules like the Hsu MBM unit. I am yet to hear the very expensive Rythmiks.Going by Martin's sheets you simply need some deep "wings", maybe 8-10", on your narrow OB on top, to make it fly !! Or even better and with the same dimensions, do a 2 way OB on top with an 8-10" midrange and tweeter...like the Basszilla.
I had started with 15" GW in H-frame and then switched to the ubiquitous Eminence 15 alpha, giving a harder punch.
Hi,
I can't see the point of the narrow OB's for the mid treble unit. MJK uses
a 20" square baffle with an offset driver, and then uses the x/o to suppress
the baffle hump you get before baffle roll off. With narrow baffles the hump
is a lot higher and a lot of boost is required to get down to the bass unit.
wings on the narrow baffle will introduce cavity resonances, not good.
rgds, sreten.
I can't see the point of the narrow OB's for the mid treble unit. MJK uses
a 20" square baffle with an offset driver, and then uses the x/o to suppress
the baffle hump you get before baffle roll off. With narrow baffles the hump
is a lot higher and a lot of boost is required to get down to the bass unit.
wings on the narrow baffle will introduce cavity resonances, not good.
rgds, sreten.
>>> I can't see the point of the narrow OB's for the mid treble unit.
I can't either.
But i did enjoy BIBs (using Fostex 165k) enhanced by H-frames so i believe something other than an OB works beautifully together. The trick with H-frames is making them look good in the room. I think of them as two big subs but with the special qualities of OB. I also think of them as speaker stands.
I can't either.
But i did enjoy BIBs (using Fostex 165k) enhanced by H-frames so i believe something other than an OB works beautifully together. The trick with H-frames is making them look good in the room. I think of them as two big subs but with the special qualities of OB. I also think of them as speaker stands.
Really like mine at approx 70-75hz and under, but over that not so much. I think it's an H-Frame thing by design that messes with the higher signals, the way the driver is walled/boxed in etc..Now if the leading part of the box could be flared out like a front horn then maybe things would be different ?..
Bob, if they don't work out for your project it would be interesting to see how you might like them as subs? I really enjoy them that way myself, and as Jeff stated they mate up real fine with the BiB cabs..
Bob, if they don't work out for your project it would be interesting to see how you might like them as subs? I really enjoy them that way myself, and as Jeff stated they mate up real fine with the BiB cabs..
So the small OB's didn't work out. I knew I was stretching things. I knew that the OB would roll off at 300 Hz. I didn't know how high I could push an H-frame. Turns out that cavity resonance ~100Hz is a killer. It takes the right music to hear it, but it's there. This causes a general smear in the mid bass. As promised, I brought out my small TL's. These little suckers will go all the way to 40Hz on their own, but not with enough SPL to be convincing.
This setup has the H-frames low-passed at 70Hz 4th order Chebechev and the TL's high-passed at 100Hz 4th order Bessell. Works great. Nice smooth transition through the cross-over helped by a serious room-mode notch. The combination gives some serious weight to the bottom, but is nice and tight -- no booming. Of course, these H-frames are not real subs. They die below ~30Hz. But there is precious little music that low.
I know that it may sound like sour grapes, but I like the TL's better than the OB's anyway. The OB's were much too forward. The TL's have a lot less pronounced baffle hump and a generally smoother sound.
This rig needs some playing with, but I feel confident about it. If you want to hear them, be in Dallas May 4th for the LSAF meet.
Bob
This setup has the H-frames low-passed at 70Hz 4th order Chebechev and the TL's high-passed at 100Hz 4th order Bessell. Works great. Nice smooth transition through the cross-over helped by a serious room-mode notch. The combination gives some serious weight to the bottom, but is nice and tight -- no booming. Of course, these H-frames are not real subs. They die below ~30Hz. But there is precious little music that low.
I know that it may sound like sour grapes, but I like the TL's better than the OB's anyway. The OB's were much too forward. The TL's have a lot less pronounced baffle hump and a generally smoother sound.
This rig needs some playing with, but I feel confident about it. If you want to hear them, be in Dallas May 4th for the LSAF meet.
Bob
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while I've heard several decent to stunningly good sounding OB systems, there are definite logistic / "real estate" issues required for them to do their magic -
you might have been able to avoid the problems with the performance / integration of bass if you had space to accommodate much larger baffle and even multiple woofers, but that's exactly my point - in simple terms they ( OB) are not for everybody's real world situations - but I've yet to find a room in which a pair of sometimes pretty dinky little TLs, "BRs", or BLHs couldn't work
Small OBs contribute a more consistent polar pattern, with better side cancellation, and with proper compensation and enough displacement you can get pretty incredible performance.
The cavity resonance at ~100hz could be due to the H frame being too deep.
I'm just paraphrasing MJK here, but the effective depth seen by the woofer is sensibly more than the actual depth (12.9" effective as opposed to 7.5" actual in Martin's Alfa 15A H-frame), and with an 18inch driver the disparity between the actual and effective could be even more pronounced.
If this is the case, then making the H frame shallower should cure the problem.
I'm just paraphrasing MJK here, but the effective depth seen by the woofer is sensibly more than the actual depth (12.9" effective as opposed to 7.5" actual in Martin's Alfa 15A H-frame), and with an 18inch driver the disparity between the actual and effective could be even more pronounced.
If this is the case, then making the H frame shallower should cure the problem.
>>> They die below ~30Hz…
Yes, they do. And the Alpha 15's only into the 40s... but the bass player sounds like he's in the room with me.
>>> I like the TL's better than the OB's anyway…
I don't see what's not to like with your current setup. To be fair, the OBs you made were not sufficient. They did look great but looks and sound are often at odds.
>>> but I've yet to find a room in which a pair of sometimes pretty dinky little TLs, "BRs", or BLHs couldn't work…
Yes, those types of boxes are popular for good reason… and you can always add a sub. They do the job!
If you have the room and don’t mind large panels staring at you then large OBs (I personally think approx. 20” x 40” is about as small as you can go for ‘full range’ sound) offer a different kind of sound that’s very enjoyable. Imaging is wider and sounds seem to emanate from within their own space more realistically. The large baffle is the key IMO. I really don’t know how these guys who hang their drivers in space get a full rich sound… but I’ve never heard a properly done implementation.
Peace,
Zilla
Yes, they do. And the Alpha 15's only into the 40s... but the bass player sounds like he's in the room with me.
>>> I like the TL's better than the OB's anyway…
I don't see what's not to like with your current setup. To be fair, the OBs you made were not sufficient. They did look great but looks and sound are often at odds.
>>> but I've yet to find a room in which a pair of sometimes pretty dinky little TLs, "BRs", or BLHs couldn't work…
Yes, those types of boxes are popular for good reason… and you can always add a sub. They do the job!
If you have the room and don’t mind large panels staring at you then large OBs (I personally think approx. 20” x 40” is about as small as you can go for ‘full range’ sound) offer a different kind of sound that’s very enjoyable. Imaging is wider and sounds seem to emanate from within their own space more realistically. The large baffle is the key IMO. I really don’t know how these guys who hang their drivers in space get a full rich sound… but I’ve never heard a properly done implementation.
Peace,
Zilla
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