Re: Meech's Folly
By the time you seal off a litre & a half for the JX35 (i'd use a damped piece of 4" PVC) & account for driver volume you are going to be under 20 litres for a driver that would really like to see 40-70 litres.
macSpeakerz works fine, i use it for sealed & (rarely) reflex boxes. It also has usful cabinet calculators. Punch in the drivers parameters, set the Q between 0.5 & 0.7 and see where it takes you.
dave
macmeech said:
By the time you seal off a litre & a half for the JX35 (i'd use a damped piece of 4" PVC) & account for driver volume you are going to be under 20 litres for a driver that would really like to see 40-70 litres.
macSpeakerz works fine, i use it for sealed & (rarely) reflex boxes. It also has usful cabinet calculators. Punch in the drivers parameters, set the Q between 0.5 & 0.7 and see where it takes you.
dave
The crossover on the Jordan website
There is a diagram of a simple 53/125 2-way crossover under
systems/application notes/JX53. Can anyone tell me what it means in
terms of good wire and the most tweaked out parts?
I can see this project coming together. I think I will call this speaker design
The Eclectic Project. I am going to replace my Wharfedale Diamonds with these.
There is a diagram of a simple 53/125 2-way crossover under
systems/application notes/JX53. Can anyone tell me what it means in
terms of good wire and the most tweaked out parts?
I can see this project coming together. I think I will call this speaker design
The Eclectic Project. I am going to replace my Wharfedale Diamonds with these.
planet10 said:
dave, i could kiss ya! thanks a lot. now i have to work 3 times as hard to get the jordans (the JX53/125 combo cost $250 while a Fostex FF85/ SEAS CA21 combo costs $80). then again the surrounds would have to JX92 instead of FE103/FW108. I assume the JX92 will work in a 12 liter box.
although this point is mute if i am gonna spring for the jordans, i am told that the FE107 (sheilded version of the FE103) is smoother than the 103. is it worth the difference if one does NOT need sheilded speakers (TV will most probably be plasma 42" cause I cant afford 52" and cause front projection means a long wire from the reciever to the projector snaking across the room).
dave,
i looked at the gif file and have a few questions.
1. can the MLTL be made with dimesions that are similar to the JTM made by Carolina audio (http://rthack.tripod.com/KOTA/Page_8.html)?
maybe internal dimensions of 36" tall x 12" wide x 3" deep? or something similar?
2. what is the principle of this design. the 3.75 " gap at the top for example is confusing. maybe an isometric view will help.
3. why is the driver in the middle of the TL?
i looked at the gif file and have a few questions.
1. can the MLTL be made with dimesions that are similar to the JTM made by Carolina audio (http://rthack.tripod.com/KOTA/Page_8.html)?
maybe internal dimensions of 36" tall x 12" wide x 3" deep? or something similar?
2. what is the principle of this design. the 3.75 " gap at the top for example is confusing. maybe an isometric view will help.
3. why is the driver in the middle of the TL?
navin said:
As long as the volume & length are maintained you can make it any shape that fits the line (tapered 3:1)
Because it is a triangulated line*, the regular 3 views make it hard to visualize. The gap at the top is the bend. The line starts at the bottom, goes up, and then back down with the terminus also at the bottom.
*(the internal baffle runs diagonally and divides the sqaure prism into a trianular line -- no standing waves)
Driver offset kills the 1st undesirable line resonance/ripple. It is actually about a 1/3 of the way from the closed end of the line.
dave
Re: The crossover on the Jordan website
macmeech said:There is a diagram of a simple 53/125 2-way crossover under
systems/application notes/JX53. Can anyone tell me what it means in
terms of good wire and the most tweaked out parts?
I can see this project coming together. I think I will call this speaker design
The Eclectic Project. I am going to replace my Wharfedale Diamonds with these.
Attachments
navin said:
The closed end of the line is 3 times the x-section of the terminus. (about 90 in^2 -> 30 in^2 and about 88 in long)
Sd has nothing to do with the line size and is imaterial* -- the parameter that is important is Vas.
*(it only relates in that Vas tends to go up with Sd)
MJK uses Sd because that came from classical design -- it is only a convention.
dave
Port diameter for JX125 MLTL
OK, so I'm intrigued too...
I fired up Martin's Mathcad sheets for a straight ML-TL with the JX125, can get a great enclosure with good SAF, but impossibly long port lengths for 4" dia ports. My Loudspeaker Design Cookbook says that a 3" port (which is managable) is OK for a 6" speaker, the Jordan is abt. 5.75" (146 mm)
But the JX125 is being asked to perform like most 8" - 10" speakers in the low end. So - do I need to go 4" diameter with the vent?
OK, so I'm intrigued too...
I fired up Martin's Mathcad sheets for a straight ML-TL with the JX125, can get a great enclosure with good SAF, but impossibly long port lengths for 4" dia ports. My Loudspeaker Design Cookbook says that a 3" port (which is managable) is OK for a 6" speaker, the Jordan is abt. 5.75" (146 mm)
But the JX125 is being asked to perform like most 8" - 10" speakers in the low end. So - do I need to go 4" diameter with the vent?
The main thing is to keep the vent mach to < ~0.05%, and a T/S max flat alignment yields ~0.04% at rated output with a 3" dia. vent. Since this assumes that the vent is being driven with 100W at Fb, chances are you can get by with an even smaller one. To stay within Xmax limits power handling to ~10W, which allows a 2" dia. to be chosen. At rated output, a 2.5" dia. only bumps it up to 0.06%, so this seems a reasonable compromise size WRT vent compression Vs power handling.
GM
GM
Re: Re: Port diameter for JX125 MLTL
dave,
I started with your posted design , kept the same cross-section & "straightened" it (Sd=S0=60 in^2), shortened it it 72 inches (giving a total enclosure height of about 30"). The driver's at 24" & I modeled a 8" long 1.5" radius port out the bottom instead of just an opening.
It gives pretty good LF extension with a fairly smooth response...
Response shown is with no stuffing. The displacement stays below 2 mm for everything above 20 Hz.
I'm a newbie who's done a lot more simulating than building speakers (my math is better than my woodworking & both are better than my finances ) so feel free to point out any problems with this approach... am I asking too much out of this small speaker?
mike the cheesehead
planet10 said:
dave,
I started with your posted design , kept the same cross-section & "straightened" it (Sd=S0=60 in^2), shortened it it 72 inches (giving a total enclosure height of about 30"). The driver's at 24" & I modeled a 8" long 1.5" radius port out the bottom instead of just an opening.
It gives pretty good LF extension with a fairly smooth response...
An externally hosted image should be here but it was not working when we last tested it.
Response shown is with no stuffing. The displacement stays below 2 mm for everything above 20 Hz.
I'm a newbie who's done a lot more simulating than building speakers (my math is better than my woodworking & both are better than my finances
) so feel free to point out any problems with this approach... am I asking too much out of this small speaker?mike the cheesehead
Oops! In my previous post these should be .....< ~0.5%...... and .......bumps it up to 0.6%......
====
>It gives pretty good LF extension with a fairly smooth response...
====
Yes, with stuffing to smooth it out and a good roll that works well for a small room or near a wall or corner.
====
>The displacement stays below 2 mm for everything above 20 Hz.
====
Note that this at 1W.
For comparison, here's a T/S max flat I did awhile back for someone, but AFAIK never built:
L = 57.28"
SO/SL = 83.258"^2
driver down 20"
vent near/at the bottom
rp = either 1.25" or 1.5"
Lp = either 4.75" or 6"
density = ~0.2lbs/ft^3
GM
====
>It gives pretty good LF extension with a fairly smooth response...
====
Yes, with stuffing to smooth it out and a good roll that works well for a small room or near a wall or corner.
====
>The displacement stays below 2 mm for everything above 20 Hz.
====
Note that this at 1W.
For comparison, here's a T/S max flat I did awhile back for someone, but AFAIK never built:
L = 57.28"
SO/SL = 83.258"^2
driver down 20"
vent near/at the bottom
rp = either 1.25" or 1.5"
Lp = either 4.75" or 6"
density = ~0.2lbs/ft^3
GM
from another poster I got that Vp = total line volume = Vas (when Qts=0.33). However if Qts = 0.25 or 0.4 or 0.5 then what is Vp? I figured there must be some equation relating Vp to Vas and Qts. so once we know Vp we can figure out the terminus and the begining crosssectional areas but we need to know VP for a particular Qts and Vas. How do we get that? Sorry but I seem to be giving Bart Simpson serious competition of late.
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