Well, this was already suggested:
In addition to that, looking through these and other forums (like Parts Express), reading and digesting what others have done, and and advice others have been given. There's several websites that have informational articles (like Audioholics ) that give some of the why behind some design topics.
Books like this and this will explain what those "random 2 letters" mean. So does this. Those two books give advice on system design too. This might be one of the best single resources for what makes a good loudspeaker. This gives a very in depth explanation of these things.
Look, you've already made progress, and you've gotten a lot of help to understand this topic. I'm sure that in the end you'll have a set of speakers that you are proud of, but this is a huge topic to learn; there is going to be some frustration and confusion getting there.
That's a real nice speaker for the money.
It may be a good value kit but I am currently putting in the work to do it myself and gain a lot of experience.
Without wanting to be rude, you are trying to design speakers without even knowing what SPL stands for.
That's like saying you want to design airplanes without knowing what lift means.
Ok so I spent a couple hours reading and thinking up. Unibox said I needed 180.6 Liters of space. If the face of my box is 16" by 30" height(2 inches in between each woofer), then a couple calculations later The length needs to be 22.9". This is of course rough math without including taking out the 0.75" thickness of the wood but am I getting the right idea? Does the measurements of the face matter? Also I read that the placement of the port doesn't matter with a wanted tuning peak below like 100Hz so that means the most logical place for the port is right in between the 2 woofers...?
Apparently You need at least the port distance away from the wall. This would be 3 inches but 3 inches seems very short for a port, did I put in a bad input?
A Maximus-18 type 3-way(1"Horn+12"mid+18" woof) can be build with ~$360 in close-out parts.
-Denovo Audio had a Maximus-18 (Horn+12"mid+18" woofer). 18" cone area > two*12" cone area.
-I suspect that many builders planned to bi-amp, and only required Denovo's 2-way 12" + horn kit.
-A Maximus-18 type 3-way can be build with ~$360 in close-out parts. Bi-Amp is good idea.
Currents budget requires using on-Sale items for ~ $300 in parts like:
$13 B-52 PHRN-1014 1" Horn 10" x 14" Bolt-On waveguide
Model: PHRN-1014|Part # 299-2303
$34 Selenium 1" compression driver 2/3 Bolt . ( Proven Xover ckt available)
Selenium 8 Ohm Model: D220Ti-OMF-8 |Part # 299-2321
$130 Eminence Delta Pro 12A midrange 12"
$75 Dayton DAS315-8 (12" woofer need 2/speaker)
or
$130 B-52 18-190S 18" Cast Frame Professional Subwoofer 8 Ohm
Model: 18-190S|Part # 299-2302
(8cuft ported tuned to 30Hz)
== Sd vs. cone diameter=
18" 1220 cm2
15" 855 cm2
12" 530 cm2
10" 345 cm2
8" 225 cm2
Attachments
The left one looks like what I'm going to build but I thought 12" mid driver is too big for my 13ft by 17ft room... The right one is different from what I am planning to build but I'm not sure the percs of having the massive 18" driver...
Will, you've got the program working right and your box volume calculation is correct (excluding thickness of the wood). Bottom placement for the port is probably used most often but the middle would work too. Back of the speaker works as well if they don't get placed right up against a wall. Keeping the port a full port diameter (so 10cm in your example) away from walls is also a good rule of thumb.
But I can't say if what you've posted is a good design for you because I also need to see cone excursion and port velocity and I need to know the max SPL above about 30Hz and how much power is required.
What you need to know is that just because the program is suggesting a certain alignment doesn't mean that that's the 1 you have to use. (alignment refers to the combination of variables that results in a specific response)
Generally my process goes something like this:
1. Choose a Vb that meets your box size goals and try a Fb that results in something close to your target F3. Your target only needs to be somewhere around 30Hz to 35Hz because a slightly more gentle rolloff is actually better at these LF.
2. Once you get a decent looking curve, check the cone excursion. Keep increasing power until the cone excursion just stays below xmax for content above about 25Hz-30Hz. This tells you how loud these drivers are going to play cleanly and how much power you need to do so.
3. Now check you port air speed. Increase or decrease the port diameter until the speed is somewhere between the red and brown lines at maximum power and SPL's. Try 2 ports just for fun. The port diameter only has to be large enough so that the max port speed is not exceeded at the largest excursion levels.
See if that helps you.
But I can't say if what you've posted is a good design for you because I also need to see cone excursion and port velocity and I need to know the max SPL above about 30Hz and how much power is required.
What you need to know is that just because the program is suggesting a certain alignment doesn't mean that that's the 1 you have to use. (alignment refers to the combination of variables that results in a specific response)
Generally my process goes something like this:
1. Choose a Vb that meets your box size goals and try a Fb that results in something close to your target F3. Your target only needs to be somewhere around 30Hz to 35Hz because a slightly more gentle rolloff is actually better at these LF.
2. Once you get a decent looking curve, check the cone excursion. Keep increasing power until the cone excursion just stays below xmax for content above about 25Hz-30Hz. This tells you how loud these drivers are going to play cleanly and how much power you need to do so.
3. Now check you port air speed. Increase or decrease the port diameter until the speed is somewhere between the red and brown lines at maximum power and SPL's. Try 2 ports just for fun. The port diameter only has to be large enough so that the max port speed is not exceeded at the largest excursion levels.
See if that helps you.
Cone excursion seems to be how much the woofer moves from it's og position but I can not find this label in Unibox nor find more info on trueaudio.com.
It looks like the graph becomes steady at ~33Hz so that seems good if that is what you meant.
Should I be looking at the graphs in thee "V
ented Box" tab?Yes, you also need to look at the graphs on that vented page. There are a bunch of them. Concentrate on the ones I already mentioned. If you are looking at a closed box, you need to look at the graphs on that page. Make sure that you have always updated the graphs on the main page before going to look at the other pages. Check out the other tabs too so you start to learn what else the program can do.
That FR does look ideal for an anechoic chamber but in the real world that kind of response tends to produce some boomy bass when it's combined with the gain you get in an enclosed room. Go back and look at the 1st 2 sets of Dayton graphs that I posted at least a few pages back as examples to get a better idea of what I'm talking about.
That FR does look ideal for an anechoic chamber but in the real world that kind of response tends to produce some boomy bass when it's combined with the gain you get in an enclosed room. Go back and look at the 1st 2 sets of Dayton graphs that I posted at least a few pages back as examples to get a better idea of what I'm talking about.
Sure. I design, test, and build my own stuff. But this kit is already designed and tested; a turnkey kit. Big difference.
For people without technical skills, it's a bargain I think. Most people don't have a clue how to match up drivers, etc. So much is sorted in this kit. They even addressed dispersion of drivers at the crossover point, something that's ignored in a lot of designs,
Of course I would try to clone it, scouring closeout deals etc.
I don't want to appear rude by saying this but I am just not interested in proven kits(I've said it a million time on this thread), I want to do it myself because it is good experience. I have expert help too making sure that I am doing the process correctly.
It seems downing the size of the box smooths the graph but tbh I am looking for boomy bass to take over the room so maybe something like 150 liters would be good?
I looked at some of the other graphs and thanks to your help the program doesn't seem nearly as perplexing as before. I attached all the main screens so tell me if I should go on and do calculations with wood thickness involved. If you think I need more practice I will do more drivers but I think I will use the dayton ones because I want the low extension. [/ATTACH][/ATTACH][/ATTACH]
Attachments
That's great. I like it too. But sometimes I see a kit that's hard to beat for the money. I might buy one some day, even though my last build turned out great. And I bought returned woofers for it too and saved about 35% on that. And I figured out why everyone returned these woofers; they're 8" woofers that are really 9" woofers. They bought them as replacement woofers and they didn't fit. That's their loss and my gain.
Yeah that's pretty weird, sending the wrong sized woofers... However it is my birthday in October and I can get all the expensive parts then making money not as big a problem.
Hey that's great to see you making progress. Don't forget to have a look at the port velocity.
Have a look at some other drivers and see if you can get the same F3 or so in a smaller box and/or for less money. See if you need the same amount of watts too. And quite frankly, you have more SPL out of 2 of those than are really good for your ears, one of them per speaker will give you more than enough SPL, but I'm not really going to argue against having the extra headroom available - that's actually a good thing.
Have a look at some other drivers and see if you can get the same F3 or so in a smaller box and/or for less money. See if you need the same amount of watts too. And quite frankly, you have more SPL out of 2 of those than are really good for your ears, one of them per speaker will give you more than enough SPL, but I'm not really going to argue against having the extra headroom available - that's actually a good thing.
Yeah I chose 2 because I want to have the extra bass available even if it is an unconventional volume... Say I am making a beat or listening to a new song and I just want to hear how it sounds at extreme volume temporarily, I just want to avoid worrying about pushing them too hard even If I won't, I just want it off my mind.
I Will put it the Eminence drivers in and see what I can do but may I ask where the port velocity input is? I recall velocity to mean the speed of something so I'm not sure how this applies...
EDIT: I actually got to get up tmrw meaning I gotta get some sleep. I will pick up on this later so goodnight.
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clipping is when you try to push 60 watts out of a 50 watt amp
over excursion is when a driver moves 6mm, despite an Xmax of only 5mm
What you are hearing might be neither.
JBL LSR308 Review
"The 1/8 inch thick plastic front baffle and 1/16 inch thick unbraced metal back plate makes this the worst cabinet I've ever seen from a material selection stand point. The back panel flexes quite a bit when inserting the power plug or 1/4 inch jack.
[...]
These need work, a sweep test shows the back amp panel on one speaker is rattling when 140-200hz is played. JBL said that they built these as cheap as possible, and they were not lying. On the plus side you get the cutting edge of tech for peanuts. "
Perhaps your first hands-on DIY effort should be to improve your existing speakers. Improving the flimsy cabinet would be an easy fix / good learning experience.
Aim for about 50 watts.
-For the budget: small amps need small (12 to 18 volt) power supplies. If you can salvage the power brick from an old laptop or similar, the power supply is free.
-Because it is sensible: Eminence and similar speakers usually hit Xmax at pretty low power. If 20 watts is enough to move your woofer to its limit, there's not much point in having a >50 watt amplifier.
Yes, yes, and yes. I have a minDSP and it is insanely good value for $
Not necessarily. For cost (one less miniDSP needed, one less amp needed) and simplicity (fewer cables and power supplies), it is possible to make a hybrid:
-music source is plugged into miniDSP
-miniDSP is plugged into amp LOW and amp HIGH
-amp LOW is plugged directly into the bass speakers
-amp HIGH is plugged into a passive crossover
-passive crossover is plugged into the midrange & tweeter
The passive crossover can be simplistic / a bit crap, and it doesn't matter. Instead of rebuilding it (repeatedly) to get it perfect, you just use the DSP to get a flatter response.
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