So due to this comment should I try to find a tweeter that will have a better off axis response or is this typical to tweeters? I know higher frequencies are more directional compared to the lower frequencies but is this something a better tweeter would fix or is this just the way it is?
Also, IF I do successfully come up with an alternate shape where the sides tape ever so slightly I would have to calculate BSC for each driver wouldn't I?....ie. if the base of the box is 16" wide where the lowest woofer is located, and 14" wide where the woofer above that is located, and 3" at the very top where the TB ti would be located....I would most likely in effect have different BSC at each driver....right? (These measurements are hopefully exaggerated for this question...I don't anticipate a slope of this magnitude in my design.)
Another Also if I may; Do Subwoofer T/S parameters assume half space or full space? Will I in effect loose 6db with my woofer from what the parameters say I'll have, or are those parameters assuming the bass will behave a certian way, meaning an 86db woofer would if only playing in halfspace actually be 92db. I guess more to the point when all the speakers are put in the box will the BSC in effect cause the mid and upper frequencies to be 6db more, OR will the bass drop meaning I'll loose 6db right from teh get go from what I think I'm getting? Any compensation via XO would just chop 6db off the top to match the lower frequencies...right?
How in the world can someone achieve 90db then? From the sound of this phenomeon even if I plan for a 90db system I'm only at 84db.....assuming you loose from the bass rather than gain the mid and upper frequencies.
http://sound.westhost.com/bafflestep.htm
This website talks like he's correcting the problem without lowering the upper frequencies but the charts he shows seems to say otherwise. Maybe I'm just not putting it all together properly yet.
As soon as you start changing box width or tweeter then you are talking about taking on crossover design as well.
I'm able to recommend the Statements as a finished/polished project because I've heard them in a typical living room.
If you are willing to do the crossover and cabinet design, with your own parts selection then you are really talking about doing a lot on a first project.
I listened to the Statements and walked around them. The dipole Tang Band gives them a large sweet spot at least at Jim's place. I didn't have the sense that they wouldn't work well in a home theater setup.
But I've heard many ribbons and planars have beaming issues. So I'm not a big fan anymore of ribbons.
For home theater, I really think the controlled directionality and SPL capability of horns is a winner.
I think the reason you got so many references to Jim's Statements is because you mentioned you liked that Tang Band. If you are open to other drivers, there are plenty of bass limited 2-way designs (Zaph, htguide) out there that you could build with PE boxes in a weekend. Most of them probably have decent output to 100hz where your sub could kick in.
I have a friend who may be starting on an Scanspeak 8531G/ 9700 MTM project soon. I expect that will be good.
I'm working on a Scanspeak 6600, XG18 project myself.
Too many ideas, from too many people. I know its hard to pick something.
I'm able to recommend the Statements as a finished/polished project because I've heard them in a typical living room.
If you are willing to do the crossover and cabinet design, with your own parts selection then you are really talking about doing a lot on a first project.
I listened to the Statements and walked around them. The dipole Tang Band gives them a large sweet spot at least at Jim's place. I didn't have the sense that they wouldn't work well in a home theater setup.
But I've heard many ribbons and planars have beaming issues. So I'm not a big fan anymore of ribbons.
For home theater, I really think the controlled directionality and SPL capability of horns is a winner.
I think the reason you got so many references to Jim's Statements is because you mentioned you liked that Tang Band. If you are open to other drivers, there are plenty of bass limited 2-way designs (Zaph, htguide) out there that you could build with PE boxes in a weekend. Most of them probably have decent output to 100hz where your sub could kick in.
I have a friend who may be starting on an Scanspeak 8531G/ 9700 MTM project soon. I expect that will be good.
I'm working on a Scanspeak 6600, XG18 project myself.
Too many ideas, from too many people. I know its hard to pick something.
Jermu-
Losing 6 dB of bass is the best way to think of it. Many (but not all--most Seas do not) driver frequency response plots show a 2pi environment. The frequencies carried by the mids and tweeter will for the most part as shown on the graphs. You will 'lose' 6db off of the bass. So how do you design for 90dB 2.83V/1M?-- you take two 90dB woofers and hook them up in parallel. The crossover design does gets all the levels to work together correctly -- did you look at the Northcreek website? George Short had a nice writeup on the method he uses for two way designs.
Your sloped baffle won't make much of a difference in the BSC network -- you will only need one "network" for BSC.
JJ
JJ
Losing 6 dB of bass is the best way to think of it. Many (but not all--most Seas do not) driver frequency response plots show a 2pi environment. The frequencies carried by the mids and tweeter will for the most part as shown on the graphs. You will 'lose' 6db off of the bass. So how do you design for 90dB 2.83V/1M?-- you take two 90dB woofers and hook them up in parallel. The crossover design does gets all the levels to work together correctly -- did you look at the Northcreek website? George Short had a nice writeup on the method he uses for two way designs.
Your sloped baffle won't make much of a difference in the BSC network -- you will only need one "network" for BSC.
JJ
JJ
I did read the Northcreek article and I googled BSC and read a few more. I think I have the general idea of what is going on, and what you are saying is in effect that the 6db gained from 2x90db woofers in parrallel should offset the -6db BSC.....makes sense. Once everything is put together I'll just test the speakers performance and tweak the XO accordingly to correct any other irregularities...right?
Now I need to find some 90db woofers....
Thanks for helping me with the BSC...I would have never know about that had you guys not brought it to my attention......
aaahhhhh so much to consider...
can someone point me to the aisle with 90db woofers that are worth a flip?
Now I need to find some 90db woofers....
Thanks for helping me with the BSC...I would have never know about that had you guys not brought it to my attention......
aaahhhhh so much to consider...
can someone point me to the aisle with 90db woofers that are worth a flip?
From http://www.zaphaudio.com/6.5test/
These are probably good, but not 90db. Large Pro woofers for use with horns would be 90db+ efficient.
Peerless 8945P SPL: 86 dB
Peerless 8945A SPL: 87 dB
Scanspeak 18W/8531G-00 87db
These are probably good, but not 90db. Large Pro woofers for use with horns would be 90db+ efficient.
Peerless 8945P SPL: 86 dB
Peerless 8945A SPL: 87 dB
Scanspeak 18W/8531G-00 87db
There are more than SPL to think about, like VAS and Qts
If you want high SPL then small TB drivers may not be the best choise
A speaker like the Elsinore is another and simple way to make effective speakers, and just fore the record its a 2.5way so all 4 drivers are playing bass
4 of them and another lying down as center(one bottom bass moved to the other end) would surely rock the house
You may not even need subs, but if you insist just close the BR ports
http://www.customanalogue.com/elsinore/elsinore_index.htm
If you want high SPL then small TB drivers may not be the best choise
A speaker like the Elsinore is another and simple way to make effective speakers, and just fore the record its a 2.5way so all 4 drivers are playing bass
4 of them and another lying down as center(one bottom bass moved to the other end) would surely rock the house
You may not even need subs, but if you insist just close the BR ports
http://www.customanalogue.com/elsinore/elsinore_index.htm
Probably the Aurum Cantus 7" or 8" drivers, or pro sound drivers as Daveis mentioned.
But you can't get something for nothing --
If you go through and figure out the closed box resonant frequencies and the F3 points for various drivers in sealed boxes, you will find you need a relatively big box to get a low (40's) Fcb and F3. I calculated what the AC's would give (if the listed spec's are accurate) -- the 6 1/2 inch driver in a .5 cu ft box will give a predicted F3 of 72 hz with an Fcb of 70 hz and Qts of .7.
72 Hz is not real low for a tower speaker, but for HT use where you can use an active crossover set to 80 or 100 hz, it is just fine.
JJ
I tell you what the more we dig the deeper this rabbit hole gets...
Question:
Can a scenario where we use small drivers to achieve the needed spl sound as good as that same spl achieved with less larger drivers? I.E. - if we use four 6" drivers to achieve the 90db will it sound as good as two 8" drivers at the same 90db as long as the VAS of the 6" drivers added up to be the same or greater than the 8's?
Also what box design software / XO software would you guys recomend? I know JJ is using Xover 3 pro...is that a good choice or would you recomend something else? I was read up on that as well as lspCAD....what are you guys' thoughts?
Question:
Can a scenario where we use small drivers to achieve the needed spl sound as good as that same spl achieved with less larger drivers? I.E. - if we use four 6" drivers to achieve the 90db will it sound as good as two 8" drivers at the same 90db as long as the VAS of the 6" drivers added up to be the same or greater than the 8's?
Also what box design software / XO software would you guys recomend? I know JJ is using Xover 3 pro...is that a good choice or would you recomend something else? I was read up on that as well as lspCAD....what are you guys' thoughts?
JerMu said:
You may want to consider taking the blue pill.
4 drivers starts down the path of line-array.
But if the Fs of your 6" drivers is 60hz then you will never hit 40hz with a million drivers.
I am running two 8" Scanspeaks ported per channel and I get plenty of bass. Four the same drivers won't go any lower in frequency.
I think the point of diminishing returns for woofers is about 2.
Matching a single tweeter with 30" to 50" of line array means matching SPL of something that is starting to become a line array with a point source. I think this is a waste of time. Both tweeter and woofer need to be line array.
Also, I've heard that if you want true line array you need to use wide range 4" drivers due to center-to-center spacing.
Nice, I like that you know what I was referring to.
Why? will you elaborate some more on this?
Yes, that Eminence/B&C combo seemed very robust, and I am considering it. I really like that those drivers are high spl and could seemingly achieve my criteria without needing to double up drivers. Where can you buy those B&C drivers at - I looked up distributors on their website and it seems like the only place is in NJ, but they don't seem to sell from their website.
I'm doing many things with this post that might be driving you guys crazy (thanks for your patience). I'm not only trying to figure out a plan for my design, but I'm also picking your brains by asking questions as they come up. I didn't really intened to use 4-6" woofers instead of 8's (unless it was the end all be all solution to the design) I just wanted to know since the spl and VAS were the same are they essentially throwing out the same sound or do larger woofers play better sound at lower frequencies and VAS/spl really doesn't factor into that.
I feel like we are starting to exaust this decision, and I need to decide what I want and what I don't, or better yet what I really want and what I can live without.
Let me pose another question to you guys:
Would you rather have a lower spl system to give you more options with drivers/design, or would you rather have a higher spl system that seems to be more expensive/difficult to design? If we are splitting hairs and a 90db system vs a 87db system is not so much then maybe I should consider that since we've already found drivers that will meet that criteria. I know the higher db system uses half the power, and should be better with dealing with distortion BUT am I really going to crank the system up to really notice the difference between 115db or 118db?
Are there other benefits that I'm overlooking or should I consider changing my criteria?
TiniTus I'm not disregarding your driver suggestion I'm just asking incase I choose to do something else or in the case that I can't purchase those drivers.
B&C driver can be bought here
http://www.usspeaker.com/homepage.htm
The 10" Eminence is also a new devellopment, seem to go pretty low even in a closed box...should match perfectly with subs
That combo will give you much better powerhandling with less compression at rocking high SPL
Those 30watt TB mids will never reach 115db, better suited fore low level quality listening
I prefer single drivers over paralelled because of less phase problems and multiple drivers means more design hazzle and also tend to get expencive ... much better to buy a few high quality drivers
I think its worth the effort, which redesigning an already well working design is not
http://www.usspeaker.com/homepage.htm
The 10" Eminence is also a new devellopment, seem to go pretty low even in a closed box...should match perfectly with subs
That combo will give you much better powerhandling with less compression at rocking high SPL
Those 30watt TB mids will never reach 115db, better suited fore low level quality listening
I prefer single drivers over paralelled because of less phase problems and multiple drivers means more design hazzle and also tend to get expencive ... much better to buy a few high quality drivers
I think its worth the effort, which redesigning an already well working design is not
For HT, an 87 dB speaker is fine. It might even be better -- low level hum is more noticeable with more sensitive speakers. There is supposed to be a difference in dynamics, but I really don't notice it. Cone breakup seems to be the only real issue for me.
90+ dB speakers would be called for if you trying to really push the envelope, with single ended class A amps for your surround system (what kind of nut would do that?
)JJ
Are you referring to a ground loop hum, or is the Low Level hum something different? If so can you clarify?
So if we lower the Spl a bit, then I should be able to pick a set of drivers much easier. I would like to achieve the highest spl that is practially possible, but lets not focus so much on 90db.
Now that we are giving on the db I know I could just build the statements or mini statments but I would like to try and achieve a smaller box design, and the mini's didn't really turn me on when I saw them. A custom box is something I really have in mind and I have not seen anything relavant to what I want to achieve (might not be doable once I get into it but I want to try first before I give up and just build something else). Everything that is trapazoidal is much more exaggerated than I want, so I'm going to go down this path until it proves too much for me then I might decide to do a previous build.
Okay a few more questions if I may:
How do I analyze a speaker to determine distortion levels and whether or not they are acceptable for my design?
How can I gauge if a speaker can sound good at high levels of power or determine at what point it starts to sound bad (as tinitus already stated the TB's wouldn't be a good choice at high levels) - how did you come to this conclusion? the 30w power recomendation; Isn't this typical for smaller speakers?
what I think I know of impedance is that it helps you to determine Xmax problems, and phase problems. when two speakers are out of phase with each other at the same frequency they cancel out one another. Are these statements true, and is this the totality of what impedance tells you?
I really think I need to start modeling boxes/XO's to try to determine what speakers I want to use...any software recommendations? I'm using winISD currently but I would like to get something where I can jump between box design and XO design all in the same software package, and winISD doesn't do XO design. I know the alpha version does but since its alpha I don't trust it.
This is not something I really worry about -- I just use good quality drivers. Try to find some reviews or other people who have used them with no problems. Zaph's site has some good distortion info, but I didn't have access to it when I did most of my builds. He tends to recommend good frequency ranges to use for drivers, too.
Not really. Impedance is DC resistance plus inductance plus capacitance (complex summation). The phase you have read about with impedence is electrical phase, and is not the same as the acoustical phase. It does not have anything to do with Xmax.
Thas is true, in terms of acoustical phase, when they are out of phase 180 degrees.
This might answer some of your questions, but it certainly can't explain everything. That would really take volumes! Keep reading! I found the best book to explain the basics was Ray Alden's 'Loudspeakers 101'.
JJ
Check out the link in this short but sweet thread. The 4" TB crossed over at 300 Hz should in fact play very loud before it reaches high distortion levels caused when it approaches Xmax.
JJ
http://www.diyaudio.com/forums/showthread.php?s=&threadid=114195
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