I must admit that I have no clue about what group delay actually is. Can someone explain it to me? As for subwoofer impulse response goes I simply don't understand that one. It seems to me that the low pass filter would remove such transients before they got to the woofer in the first place. The rise time on a 60Hz signal must be pretty leisurely no?
I have always assumed that muddy bass was due to something else entirely since bass is slow by definition. Possibly some interaction of reflections or uneven response. Now maybe a bit of overhang from uncontrolled resonance would relate directly to Q. It would seem that any muddiness must be on the back side of the signal, kind of like an echo.
I have always assumed that muddy bass was due to something else entirely since bass is slow by definition. Possibly some interaction of reflections or uneven response. Now maybe a bit of overhang from uncontrolled resonance would relate directly to Q. It would seem that any muddiness must be on the back side of the signal, kind of like an echo.
Brad's build looks great - re; fast drums - for me some sort of Karlson might work and use good 300W/side - I don't like the looks/aspect of this 42" tall coupler - that's an old Eminence 18 with Qts ~0.3 and fs 20, I've used lower mass EM 18 with Qt~0.25
An externally hosted image should be here but it was not working when we last tested it.
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Plate amps with MJK OB
First, thanks MJK for the OB articles.
Is anyone else here using subwoofer plate amps to drive the woofers in an MJK open baffle set up?
I'm using the speaker level inputs on the sub amps from my amp binding posts and utilizing the low pass crossover of the plate amp to blend the bass with the full range. I'm running the full range driver, full range.
I'm using two PE 100watt sub plate amps which cost under $200. I'm able to vary the gain and crossover depending on what full range driver I combine with the woofer.
First, thanks MJK for the OB articles.
Is anyone else here using subwoofer plate amps to drive the woofers in an MJK open baffle set up?
I'm using the speaker level inputs on the sub amps from my amp binding posts and utilizing the low pass crossover of the plate amp to blend the bass with the full range. I'm running the full range driver, full range.
I'm using two PE 100watt sub plate amps which cost under $200. I'm able to vary the gain and crossover depending on what full range driver I combine with the woofer.
Been listening over a week and have to say this speaker does the whole frequency range damn good and at low levels too!!!
My first impressions told me something was going on with the Jordan's on the top end but only when cranked to insane levels. Now I know the drivers aren't broke in yet and do think they have improved with the now estimated 100 hrs.
Upon further research of the Jordan I came across Jim Griffin's use with the Aurum Cantus G2Si here
http://www.diyaudio.com/forums/full-range/81634-jordan-ribbon-mltl.html
and after reading his pdf I think I was experiencing the attributes he described in the first couple of paragraph's.
http://documents.jordan-usa.com/JX92SG2siDesignPak.pdf
After reading Jim's thread I saw Martin's post that he acquired some G2Si's.
http://www.diyaudio.com/forums/full-range/81634-jordan-ribbon-mltl-3.html#post1708130
I now have to ask if you see yourself doing this in the future Martin? Not saying that there is any real need for an improvement over the two way but this may bring it to another level by creating a wider sweetspot with more air.
I can see now how Craig must be loving his setup too.
http://www.diyaudio.com/forums/full...ood-gw-1858-woofer-h-frame-7.html#post1976618
Brad
My first impressions told me something was going on with the Jordan's on the top end but only when cranked to insane levels. Now I know the drivers aren't broke in yet and do think they have improved with the now estimated 100 hrs.
Upon further research of the Jordan I came across Jim Griffin's use with the Aurum Cantus G2Si here
http://www.diyaudio.com/forums/full-range/81634-jordan-ribbon-mltl.html
and after reading his pdf I think I was experiencing the attributes he described in the first couple of paragraph's.
http://documents.jordan-usa.com/JX92SG2siDesignPak.pdf
After reading Jim's thread I saw Martin's post that he acquired some G2Si's.
http://www.diyaudio.com/forums/full-range/81634-jordan-ribbon-mltl-3.html#post1708130
I now have to ask if you see yourself doing this in the future Martin? Not saying that there is any real need for an improvement over the two way but this may bring it to another level by creating a wider sweetspot with more air.
I can see now how Craig must be loving his setup too.
http://www.diyaudio.com/forums/full...ood-gw-1858-woofer-h-frame-7.html#post1976618
Brad
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Brad,
I bought the AC ribbons intending to add them to the Jordan OB but I never actually felt the need. They are still unused sitting in the boxes behind my couch. I will save them for the next speaker design.
Martin
I posted a while back on the Goldwood's with the Jim Griffin Jordan/AC design on top. Very nice and matches well. Not currently listening to them as I went to the 15" Eminence (actually now the Selenium) with the Alpair 12 on top. More sensitive and a bit more detail. My power amp went out when I switched to the Seleniums, so have not had time to do a real comparison with the Eminence since I am using a spare amp for now, but will say more later.
I have started, not really intentionally, a collection of 15" woofers and a bunch of 3" to 4" full range drivers (Alpair and Fostex mostly) that could be mixed and matched to find good combinations. A modular OB that can take the different driver combinations may be my next build.
The older Alpair drivers I have model really well in an OB. I have looked at the new Alpair 7 and 12 and they also look good. What are your impressions of the Alpair 12 compared to the Jordan you also have heard? The big Alpair is an interesting looking driver.
The older Alpair drivers I have model really well in an OB. I have looked at the new Alpair 7 and 12 and they also look good. What are your impressions of the Alpair 12 compared to the Jordan you also have heard? The big Alpair is an interesting looking driver.
I have both the Alpair 7 and the 12. The most important thing I have learned is to believe what Mark says about them needing over 200 hours to break in. At first, I preferred the 7's over the 12's as the 12's actually seemed a bit bright. Now that they are broken in, the 7's seem a bit thin and the 12's sound awesome.
Not a scientific measurement, just an opinion, the 12's sound a bit more detailed and a bit fuller than the Jordan's. However, again, I look forward to having my AR amp back and having time to do some serious comparisons. That means building an OB for the Jordan's so I am really comparing OB to OB instead of to the Jim Griffin design. Bottom line is that I have no regrets about buying the Alpairs once they broke in.
You can see pictures at AZDIY2009 Detail Photos
Craig
Not a scientific measurement, just an opinion, the 12's sound a bit more detailed and a bit fuller than the Jordan's. However, again, I look forward to having my AR amp back and having time to do some serious comparisons. That means building an OB for the Jordan's so I am really comparing OB to OB instead of to the Jim Griffin design. Bottom line is that I have no regrets about buying the Alpairs once they broke in.
You can see pictures at AZDIY2009 Detail Photos
Craig
Available wood. I threw them together in a hurry. Interesting you should ask as I have since added 4 inches on one (out) side and 3 inches on the other (in) side of the Alpair 12 OB with an increase in detail. Don't know for sure if it was adding width or just the break in, but the added width did seem to help.
Interesting, maybe the highs drop down so u can hear more detail in mid freq.
I have Alpair 10FR in GM's ML-TL (slightly undersize), and Alpair 10 bass + Alpair 5 waiting to have a house.
I saw this thread 2months ago, which was very intersting, since i always want a clean low bass.
Im trying to figure out which woofer can do. So far the available would be PA audio from thailand which have qts about 0.7
Cheers
henry
I have Alpair 10FR in GM's ML-TL (slightly undersize), and Alpair 10 bass + Alpair 5 waiting to have a house.
I saw this thread 2months ago, which was very intersting, since i always want a clean low bass.
Im trying to figure out which woofer can do. So far the available would be PA audio from thailand which have qts about 0.7
Cheers
henry
Daryll Hawthorne has come out with what he call the Stackables that is a very elegant modular design. I 've been fortunate to try the beta duet at my house for a week which was a treat for a differant perspective for an OB other than yours that didn't disappoint.
Hawthorne Audio • View topic - Stackable
In the pics you can see how a driver is mounted to a baffle then bolted to the back of the stackable and can also be somewhat isolated. From you past comments on your carpenter skills a similiar idea for testing wouldn't be too far out.
Brad
I totally agree as my Alpair 12 has over 300 hours on and I love them more and more. I could never imagine it sounds so sweet and rich. I suppose to have my report submitted after 300 hours as promised, but I forgot to start writing anything when the system is on. What I need now is a little bit more air at the top.
Attachments
albertli, funny to see your Goldwood H-frames with OB Alpairs. I have Alpha H-frames with (at the moment anyway) Tangband w8-1808s... i also have unused BIBs but behind the listening spot. If you ever go back to the BIBs you will see they do have compelling qualities too. But currently I am enjoying these relatively modest costing open baffle systems that really cost very little in comparison to the electronics used to power them. I also agree, your pleasantly shaped baffles have a nice organic look compared to the rigidly angular rectangles that adorn my room. Enjoy!
Godzilla
Godzilla
Brad,
I have considered that type of construction for a few months. The number of combinations I could try is amazing, many months of fun. Thanks for the link. I had not seen the modular construction actually accomplished before, it looks like a great approach. I will study the pictures and see what I can design to take advantage of my driver collection.
Thanks for the heads up,
Martin
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