Again Martins math works out(lord knows i have borrowed his math in the past). The 15A has the proper Qts to support a low frequency wave from a narrow baffle. The only thing that can exceed the Fs of a given driver is 1/4 wave tuning or horn. An IB is the best, but who can afford the volume displacement.
I am sitting here listening to my OBs at a normal volume ( 80-85 Db, dependant on the music). It does what i want, nothing more , nothing less.
A SET is out of the question. It takes a given energy to move a given mass in a given time. If you want closer to audio perfection at normal levels then BI -amp. A power house clean amp driving the LF woofers an SET driving the mid/high. My choice is something on the order of a Marantz 22XX or a Mac1500-1900 to work the entire system.(they are old, like me)
Just an opinion.
ron
I am sitting here listening to my OBs at a normal volume ( 80-85 Db, dependant on the music). It does what i want, nothing more , nothing less.
A SET is out of the question. It takes a given energy to move a given mass in a given time. If you want closer to audio perfection at normal levels then BI -amp. A power house clean amp driving the LF woofers an SET driving the mid/high. My choice is something on the order of a Marantz 22XX or a Mac1500-1900 to work the entire system.(they are old, like me)
Just an opinion.
ron
Thanks ron for voicing your opinion.
Sorry, I do not understand all of the math behind the design details, lacking the experience and education.
I was under the impression that a high Qts bass driver like the Eminence Alpha 15A is desirable for its lower frequency ability when being used on an OB?
In my situation, I am looking for around 80Hz on the bottom of the OB. Where a subwoofer driven with a solid-state amp would work below that.
Would my proposed driver compliment, 132LB and pair of Delta 12B woofers per channel with a Qts of .30 and.48 prospectively, be much more efficent over the 15A/FF85k combination with a Qts of 1.26 and .44 on the 20" x 38" open baffle? Therefore easier to drive with a low powered SET?
Thanks
Norris
PS. "(they are old, like me)" That is partially a state of mind.
I just turned 51 in January, and I am not as quick as I use to be.
So, I am starting to get an understanding of your statement.
But, I feel I am far from being old just yet.
I usually consider age a sign of wisdom, and always have had respect for my elders, at least the respectable ones.
Sorry, I do not understand all of the math behind the design details, lacking the experience and education.
I was under the impression that a high Qts bass driver like the Eminence Alpha 15A is desirable for its lower frequency ability when being used on an OB?
In my situation, I am looking for around 80Hz on the bottom of the OB. Where a subwoofer driven with a solid-state amp would work below that.
Would my proposed driver compliment, 132LB and pair of Delta 12B woofers per channel with a Qts of .30 and.48 prospectively, be much more efficent over the 15A/FF85k combination with a Qts of 1.26 and .44 on the 20" x 38" open baffle? Therefore easier to drive with a low powered SET?
Thanks
Norris
PS. "(they are old, like me)" That is partially a state of mind.
I just turned 51 in January, and I am not as quick as I use to be.
So, I am starting to get an understanding of your statement.
But, I feel I am far from being old just yet.
I usually consider age a sign of wisdom, and always have had respect for my elders, at least the respectable ones.
I suppose I should show this simple OB setup sorta based on MJK passive OB . I have done this successfully many times & tried the Seas MCA 15 RCY last night. It is playing as I type & is wonderfull. My planars were scooted to storage.........300B PPamp w/ #10 DHT pre leading the way. I can say there is no peaky, piercing, shouting, or anything offensive. Very nice tone & detailed but natural, just a coil on the 12" & a 5uf cap on the MCA 15 RCY. Dual subs set @ about 60hz I think. I can't hear any seems & plays wonderfull. I would say that the SEAS MCA 15RCY is a driver to look into for this MJK application. At 58.00 per driver it is a no brainer for me. The smoothness is excellent. Also I am not running a tweeter yet & don't feel compelled to get one. I am sure I will but not in any hurry..
Norris Wilson said:
Hi,
Somehow I have the impression that a boxed subwoofer will not mate well with the OB's of any kind. Regarding various driver efficiencies, I can tell that biamping will alleviate many troubles.
I see that many people painfully try to integrate various drivers, yet want to drive them from a single amp. It may seem simpler, but it is not. Many OB's sound bad because of the unmatched driver efficiencies,and driver/amp are not really matched for each other. (SET must also drive the bass, or a high power SS must also feed a fullranger)...
regards,
Vix
ttan98 said:
I do not believe that just because you are using an active crossover and EQ that you can just throw any two drivers together on an OB and get an optimal result. Driver relative efficiency's and Qts values are still important variables. Using an active crossover and an EQ you can force two drivers to work together but I do not believe it will always be the best or most cost effective result, the key concept here is forcing drivers to work together. I do not believe that using EQ in combination with a low Qts driver is the most efficient way to obtain adequate bass output from an OB. Using simulations to match driver properties and size/shape the OB is a huge short cut and will assure the DIYer of a good chance at success the first build.
MJK said:
I use twin woofers mounted in U-frame, with average Qts, around 0.6 with combined spl comparable or less than the parallel mid-drivers. The combo works quite well.
the main obstacle is that the woofer is very cheap and the speed of the driver cannot catch up the the mid-driver and tweeter(I use compression driver). I think perceived speed cannot be stimulated from using s/w. The only way is change the brand of woofer I think.
Hi Vix,
I was refering to a U baffle subwoofer from my original post.
I forgot to include that important U in my subwoofer description with solid-state amp in my follow up.
For what it is worth, I have heard the Bastani Apollo OB speaker with a box subwoofer at the 2007 RMAF. And I did not feel that the woofer integrated well with the OB midrange of the Apollo.
But, show conditions are not always the best place to make a final judgement of their sound quality. There are just to may variable to take into consideration.
Norris
I was refering to a U baffle subwoofer from my original post.
I forgot to include that important U in my subwoofer description with solid-state amp in my follow up.
For what it is worth, I have heard the Bastani Apollo OB speaker with a box subwoofer at the 2007 RMAF. And I did not feel that the woofer integrated well with the OB midrange of the Apollo.
But, show conditions are not always the best place to make a final judgement of their sound quality. There are just to may variable to take into consideration.
Norris
Hi Sampo!
For all what's it's worth, this is a comment from a owner of Sonido's.
Gu Jimu
Me, myself and I have not compared with anything else.
Cheers,
Peter
For all what's it's worth, this is a comment from a owner of Sonido's.
Hello Peter!
I'm not gonna talk much. There are lots of parameters besides the main ones of Thiele-Small. With all my respect but not the Fostex nighter Lowther in their quantity of Xlin are made to generate electron or rock music or other music, saturated with low frequences. Below 60-70 Hz they rapidly pass on to unlinear magnetic field, with all the incoming consequences.
I don't know how he achieves it, but Ishtvan loadspeakers join in them ease, refinement, Full-Range detailed, tight and power of two, three-way loudspeauers.
I spend a lot time with Fostex, Jordan JX 92S. Most I like Jordan. But once I've heared Ishtvan loadspeakers, I find out I was already arrived.Other priority is that Ishtvan makes the loadspeakers along with the boxes.
And if you observe all the requirements towards the box, you will be given with real delight.!
Gu Jimu
Me, myself and I have not compared with anything else.
Cheers,
Peter
chakija said:THANKS !
I will definitely try them ,but i do not know which one i should chose.Smaller one (the one from a link above) is 92 db ,and i think that i would need to attenuate it to get proper response with 1 alpha ??
Larger one ,is
[url]http://www.sonido.hu/adat_pdf/sfr/sfr178-8.pdf[/URL]
in diameter and has 94 db.Now ,i can't afford 2 more alpha's right now ,but i think when i buy them i wont need any attenuation on this driver.Until i buy 2 more alphas ,i would listen them with attenuation ofc.
However ,if this smaller 92db driver doesn't need attenuation with one alpha ,then it would be mu choice because i don't have extra expense.
What should i do ?
Hi,
It is likely you will need to attenuate it wiith one Alpha. I cannot see
the reasoning against attenuation, the level a single Alpha puts out
will not change. In fact I'd say attenuation is the better option as it
will raise the Qtc of the driver and give you some flexibility for tonal
correction, e.g. treble boost.
/sreten.
I would like to agree with ttan98 above.
My coming into dynamic OBs was when my Magnepan MG 1.5QS needed renovation. Then I decided to try to build my own OB. I first started with Ciare CH-250 alone (quite good when properly equalized) then got the B200 which I paired with cheap chinese but decent performing woofers, see: http://www.audiocircle.com/circles/index.php?topic=40594.0 .
However with these cheap units you have at times a feeling that tones are not 100 % reproduced because of manufacture compromises. And you can definitely hear them produce 'sloppy' sounds ie sounds that are not as distinct or a bit more resonant than you know they should be. These passages are in fact easily identified.
In my 'Volks-OB' I changed to bassunits with more professional built quality: http://www.audiocircle.com/circles/index.php?topic=46951.0, links to the bass-unit is in this thread. The quality improvement is more than subtle, my bass is now distinct and fast. So I would in fact endorse taking some time to think about the best compromises economically and performancewise. I wouldn't say that the cheap woofers were bad, they were not but there are better for a little more money !
/Erling
My coming into dynamic OBs was when my Magnepan MG 1.5QS needed renovation. Then I decided to try to build my own OB. I first started with Ciare CH-250 alone (quite good when properly equalized) then got the B200 which I paired with cheap chinese but decent performing woofers, see: http://www.audiocircle.com/circles/index.php?topic=40594.0 .
However with these cheap units you have at times a feeling that tones are not 100 % reproduced because of manufacture compromises. And you can definitely hear them produce 'sloppy' sounds ie sounds that are not as distinct or a bit more resonant than you know they should be. These passages are in fact easily identified.
In my 'Volks-OB' I changed to bassunits with more professional built quality: http://www.audiocircle.com/circles/index.php?topic=46951.0, links to the bass-unit is in this thread. The quality improvement is more than subtle, my bass is now distinct and fast. So I would in fact endorse taking some time to think about the best compromises economically and performancewise. I wouldn't say that the cheap woofers were bad, they were not but there are better for a little more money !
/Erling
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