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Old 17th September 2009, 01:21 PM   #6001
thadman is offline thadman  United States
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Quote:
Originally Posted by JoshK View Post
How many 15s per side are you suggesting is sufficient?
I don't believe that's something you can generalize.

You'll have to assess your specific application (output goals, bandwidth) for quantification.
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Old 17th September 2009, 03:14 PM   #6002
soongsc is offline soongsc  Taiwan
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Quote:
Originally Posted by TrueSound View Post
A real bass horn is very good, a real OB bass system is better (in our small listening rooms.)

When using a phony horn like Olson speaks of here or using too little surface area in the OB's like only a couple of 15's a side I say why bother in spending so much time and effort with such a poor mediocre performance compromise?
We need to consider the punch of the bass and reverberant characteristics.
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Old 17th September 2009, 03:28 PM   #6003
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Quote:
Originally Posted by JoshK View Post
How many 15s per side are you suggesting is sufficient?
I think two per side is adequate down to around 140 Hz. Four to 100 Hz, eight to 60 Hz.

A single 15 in a proper 1/4 size bass horn with a 50 Hz flare will do as well as eight high QTS, high sensitivity OB 15's. Placement is easier for better results with the OB bass and the OB bass should sound less resonant and more realistic.

Most horns (all that I have heard) that are folded like the one Olson pointed towards or suggests is really only good for an octave (the vent is a joke) or at most two and will really be colored. Four 15's in a line on an open baffle would be a better choice for the band he wants to cover.
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Old 17th September 2009, 03:55 PM   #6004
Pano is offline Pano  United States
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So it's come around to "Bass Reflex vs Horn vs OB" has it? =)
OB does sound great, but it sure has its limitations, as mentioned here. Not very efficient and rarely plays very low - despite claims to the contrary. But clean!
Big boxes are great, but they can be boomy if you're not careful.. I know, I have a pair of 400L boxes now. The right driver helps. The Onken style does not need much bracing as the port structure takes care of that. It's great if you have the right driver.
Horn bass is wonderful, if you have the room. Build it into the ceiling or the basement.
Gary's "V-bass" (or whatever you would call it) is a darn good compromise. Not huge, good extension with modest EQ. Super clean. Not an easy build, tho. The table saw jig he had to build just to cut the box internals is quite a piece of work in itself!

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Old 17th September 2009, 04:23 PM   #6005
JoshK is offline JoshK  Canada
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Quote:
Originally Posted by panomaniac View Post
So it's come around to "Bass Reflex vs Horn vs OB" has it? =)
OB does sound great, but it sure has its limitations, as mentioned here. Not very efficient and rarely plays very low - despite claims to the contrary. But clean!
Big boxes are great, but they can be boomy if you're not careful.. I know, I have a pair of 400L boxes now. The right driver helps. The Onken style does not need much bracing as the port structure takes care of that. It's great if you have the right driver.
Horn bass is wonderful, if you have the room. Build it into the ceiling or the basement.
Gary's "V-bass" (or whatever you would call it) is a darn good compromise. Not huge, good extension with modest EQ. Super clean. Not an easy build, tho. The table saw jig he had to build just to cut the box internals is quite a piece of work in itself!

Nothing new - just sharing.
So split the difference and use a box for bass below the lowest room mode and OB from sub up through midbass.

Still it is hard to get around hoffman's iron law. I too had planned to go OB and mate with hi-eff top, but that proves to be difficult if you are trying to get extension, keep efficiency up and have it pass the WAF for living room dwelling.

I went for the BR with PRs, with one AES TD15X per 4.5cuft box and two PRs. I tuned for only 10hz extension below what a sealed enclosure would deliver, F3 ~48hz iirc, which keeps group delay lower while providing less excursion and greater power handling. I'll add an IB sub if needed.

Its all about trade offs, there are no easy buttons.
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Old 17th September 2009, 04:32 PM   #6006
Jmmlc is offline Jmmlc  France
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Hello,

What about a Le CLeac'h bass horn (for what I know at least 5 of them have been built here in France ).

Here are 2 examples:

http://www.diyaudio.com/forums/attac...6&d=1236807427

http://img383.imageshack.us/i/dsc30511280x768ac0.jpg/

If you have sufficient height in your listening room then it is the perfect solution until 350Hz.

Best regards from Paris, France

Jean-Michel Le Cléac'h


Quote:
Originally Posted by panomaniac View Post
So it's come around to "Bass Reflex vs Horn vs OB" has it? =)
OB does sound great, but it sure has its limitations, as mentioned here. Not very efficient and rarely plays very low - despite claims to the contrary. But clean!
Big boxes are great, but they can be boomy if you're not careful.. I know, I have a pair of 400L boxes now. The right driver helps. The Onken style does not need much bracing as the port structure takes care of that. It's great if you have the right driver.
Horn bass is wonderful, if you have the room. Build it into the ceiling or the basement.
Gary's "V-bass" (or whatever you would call it) is a darn good compromise. Not huge, good extension with modest EQ. Super clean. Not an easy build, tho. The table saw jig he had to build just to cut the box internals is quite a piece of work in itself!

Nothing new - just sharing.
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Old 17th September 2009, 04:44 PM   #6007
Pano is offline Pano  United States
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Quote:
Originally Posted by Jmmlc View Post
What about a Le CLeac'h bass horn (for what I know at least 5 of them have been built here in France ).
And I may build the first one in the USA. =) But there is much work to do in my listening room first.

What would you think about putting it in the ceiling and using the front wall as the "floor". Something like Mr. Hiraga's new room?
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Old 17th September 2009, 04:49 PM   #6008
gedlee is offline gedlee  United States
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Lets not forget my personal favorite - multiple bandpass subs to closed box mains. Efficient, small, low cost and very smooth response.
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Old 17th September 2009, 07:16 PM   #6009
ScottG is offline ScottG  United States
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Quote:
Originally Posted by Lynn Olson View Post

Regarding the various bass topologies, here's what I've been thinking ...

I was initially enthralled with the open-baffle concept, but the sad fact is that small-driver (less than 12") systems require heavy equalization (6~20 dB) and are dynamically compromised, and large-driver arrays (2x15, 4x15 or more) are physically huge and create substantial reaction forces on the baffle.
An OB can still be a LOT easier to implement well than a horn. The mouth flair on the omni-top will be audible in a critical listening context. Plus you still have all the cabinet resonances ++ (..especially when augmented with a bass reflex in the lower midrange). For sound reinforcement it's an excellent design, for hifi it has several things going for it, but with multiple failures as well. Suggestion: look elsewhere from the omni-top.

Also, remember that with any design you still have your amplifier's reaction to rising impedance near fs. IF the impedance curve is in the correct location, you can often compensate for baffle loss/dipole cancellation. Again, consider the Jensen Neo 15-150 16 ohms in parallel on a OB about 19" by 32". It would still need the midrange driver to fill-in between 200 Hz and up to as high as 1200 Hz, but it should give you pretty good gain for the lower midrange in an OB configuration. (..on the other hand crossing that low has several advantages, like reducing the upper freq. break-up from the Jensen's and allowing you to place the midrange high enough to alter floor bounce for a given listening position.)

Note that an OB's large reaction forces are largely a matter of mass and excursion - both necessarily relating to freq. extension. Keep the bandwidth from extending much below 75 Hz and it shouldn't cause a problem for the design.

If you want to pursue another route then Olimpiaudio.com has some exceedingly efficient 15" drivers for a sealed, aperiodic, or bass-reflex design. Not cheap though, and I'd suspect that the result, while more extended, would result in a very large cabinet. (..though in a smaller cabinet with a well done aperiodic venting, *could* get you something closer to what you are looking for.)
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Last edited by ScottG; 17th September 2009 at 07:38 PM.
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Old 17th September 2009, 07:50 PM   #6010
agent.5 is offline agent.5  United States
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Quote:
Originally Posted by ScottG View Post
It would still need the midrange driver to fill-in between 200 Hz and up to as high as 1200 Hz, but it should give you pretty good gain for the lower midrange in an OB configuration.
I think what you guys should consider is using

DR280 (size 24" x 24") from around 130hz up to 1000hz. I just guess that a horn lower mid may integrate better with an AH-425 than open baffle.

From 130hz and below, use BudP's designed cardoid sub and rotate it 90 degree. So, it will sit below the DR280.

I suggest open baffle servo subs by GR-Research and Rythmik.

GR-Research will have its V1 at RMAF; supposely it sounds very good and the open baffle servo sub is good up to 200Hz. Maybe Lynn can listen to it there and let us know what you think.

Last edited by agent.5; 17th September 2009 at 08:07 PM. Reason: x
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