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Multi-Way Conventional loudspeakers with crossovers

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Old 12th July 2018, 01:46 AM   #261
WillHoog is offline WillHoog  United States
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I would want to keep the whole project under $700 including amps. Right now I don't have an amp, I have my headphones and JBLs hooked up to a mixer. Also I think the only tool I will need to buy is a $30 jigsaw, my dad will have the rest. (Unless and router is necessary because I don't think we have that)
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Old 12th July 2018, 02:46 PM   #262
jReave is offline jReave  Canada
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Just to be clear, so that's $700 for everything? So for the whole speaker, the amp and any necessary tools? Do you by chance have any access to any supplies at some kind of reduced costs? Like wood or insulation?

You may want to start with finding an amp. You are likely to need about 40-70W into 8ohm to achieve your desired SPL's depending on the woofer choice. But then you'll want headroom of at least 3dB if not 6dB. In terms of amplification, every time you increase the SPL by 3dB, you need to double the power. So if you need say 50W for your max SPL, 3dB of headroom will require 100W and 6dB of headroom will require 200W. The amp should also be capable of driving 4ohm speakers.

For your budget, I'd say under $100 for the amp should be your goal. I haven't really looked at amps for years so I don't know what that kind of money is going to buy, so I can't give you much help there, maybe someone else can do so or perhaps you need to start a new thread in the amp section for that. Perhaps going with something used might be a good choice.
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Old 12th July 2018, 08:17 PM   #263
WillHoog is offline WillHoog  United States
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Yes $700 for everything, my dad has extra wood but not the right thickness, kind, or size. I will ask about insulation though. I might be able to put some of my own money in the amps if necessary, not all of it needs to be for my bday. I actually think I will buy the wood before hand and build the box earlier but I am not sure. I still need to buy some $70 speaker stands and I want a new keyboard so I will see. Plywood is cheap according to my parents so I would say $600 to $700 for everything besides the wood.

Also, I know this is completely off task and I don't really want to ask this here but I don't know where to go for this rather specific question...

My mixer has 3 frequency knobs, low mid, and high. To get the realistic sound coming from the computer I have these at the minimum which is -15. When I put them all at the middle which is 0, I like the sound, it is less dead. When I try doing this in the parametric EQ in Fl Studio, I can't simulate the sound, it sounds very different...
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Old 12th July 2018, 09:40 PM   #264
weltersys is offline weltersys  United States
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Quote:
Originally Posted by WillHoog View Post
Also, I know this is completely off task and I don't really want to ask this here but I don't know where to go for this rather specific question...

My mixer has 3 frequency knobs, low mid, and high. To get the realistic sound coming from the computer I have these at the minimum which is -15. When I put them all at the middle which is 0, I like the sound, it is less dead. When I try doing this in the parametric EQ in Fl Studio, I can't simulate the sound, it sounds very different...
What's the question ;^)?

Depending on the "Q" (width of boost or cut), cutting the low/mid/high tone controls by -15dB will probably leave peaks of as much as -6 dB between the low/mid and mid/high frequency centers, which would look like a roller coaster track. I can't think of that as a "realistic sound", seems you may be using the mixer's tone controls as an attenuator, not what they are designed to do.

If you adjust the "Q" of a parametric EQ to the same bandwidth as the mixer's EQ it could sound similar. Using a RTA (real time analyzer) would allow you to see what you hear, and start getting a grasp on the decibel scale, EQ function and frequency.
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Old 12th July 2018, 11:01 PM   #265
WillHoog is offline WillHoog  United States
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Originally Posted by weltersys View Post
What's the question ;^)?

Depending on the "Q" (width of boost or cut), cutting the low/mid/high tone controls by -15dB will probably leave peaks of as much as -6 dB between the low/mid and mid/high frequency centers, which would look like a roller coaster track. I can't think of that as a "realistic sound", seems you may be using the mixer's tone controls as an attenuator, not what they are designed to do.

If you adjust the "Q" of a parametric EQ to the same bandwidth as the mixer's EQ it could sound similar. Using a RTA (real time analyzer) would allow you to see what you hear, and start getting a grasp on the decibel scale, EQ function and frequency.
Still don't want to get too off task but there is no "Q" in the equalizer... Also the -15 on the mixer is just the lowest the knobs go and is the same sound that the computer is sending to it. putting everything on 0 sounds very much more alive and that is what I'm trying to simulate in FL studio. Maybe I should open a new thread for this? or is there a simple answer?
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Old 13th July 2018, 12:39 AM   #266
jReave is offline jReave  Canada
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Speaker Budgeting

So what you need to do is a cost analysis of basically everything except the drivers. Get out a piece of paper (or 2) and start making a list of everything you are going to need to buy for the project. And there shouldn't be any "well, this is going to be cheap so I won't include it" type of thing - every little expense adds up and in fact it's often smart when budgeting to build in a 5 or 10% leeway for unforeseen costs.

Maybe break it down something like this.

Tools: You should have a table saw, a router and a drill. However, a circular saw used with a long and true straight edge can work in conjunction with getting your wood supplier to make a few major cuts for you. It is possible to substitute a jigsaw for a router but it is trickier to flush mount the drivers that way and to do 45 degree chamfers on the rear of the driver cutouts. You can cheat in terms of flush mounting by glueing a 1/4" piece of board on top of the front baffle, but you have to be very exact with the cutouts. Best to finish them up with sandpaper I think. For your router, you'll need a 1/4" or 1/2" straight bit, a 3/4" 45 degree chamfer bit and a 3/4" roundover bit, the latter if you want to manually flare your port ends on the baffle. And fair warning, router bits aren't cheap. You'll also need a soldering gun and solder. And probably at least 4 decent size clamps although using heavy weights can work as well.

The Cabinets (Again to see how it can be done right, have a look at some of Troels' big speaker designs)

Wood: You will want to use 3/4" material. One of the best is very good quality Baltic Birch plywood that has no voids and many thin layers but it is rather expensive so forget about that. Most people on a budget will use MDF which makes good cuts and can be painted to an excellent finish but the edges are notorious for splitting if you screw into them. Plan on glueing MDF together only. There are other materials you can use (for eg) but it is often how you are going to finish them that makes a difference. Plywood is stiffer than MDF so it's better for bracing, but on a budget, MDF will have to do. Count on bracing all the cabinet walls with something like 1" x 3/4" strips. To be really picky, you'd place them about every 4" or so, but on a budget, about every 6 or 7" might do. And you'll want to place them side to side, front to back and top to bottom. Helps if they are tied into each other too to form a sort of matrix. There are other ways of doing it but this works well and uses the least wood so it's also the cheapest. The mid (and usually the tweeter is included as well) needs to be in its own separate closed chamber. Depends on the driver but about 5-8L of space should suffice.

So draw up a rough cabinet diagram with a total internal volume of somewhere around 160-170L. That should work for the woofers you've been looking at. Figure out how many sheets of 4' x 8' material you'll need for it and any other kind as well and cost it out. Expect to be in the $100 ballpark.

Damping and Insulation: Cabinet walls should be damped with something like bitumen pads, like these for eg, but on a budget you might be forgiven for skipping them. But you should use some kind of insulation to absorb at least some of the drivers' rear sound energy. You can buy acoustical foam made for the purpose but, again expensive. Many people opt for memory foam mattress toppers, say like this from Walmart. Others use 1/4" or 1/2" heavy felt, or I've seen foam rug underlayment pads (pic below) used as well. The key thing with any type of foam is it has to be open cell or breathable in other words. For the mid chamber, you should also stuff it with a little polyfill type light stuffing. So you need enough to cover all the interior surfaces which means just about as much square footage as the wood you need. Expect to spend up to about $75 unless you happen to score some kind of awesome deal.

Ports: You have the choice to buy plumbing pipe (ABS) or something like a Precision flared port from PE. Price each 1 out to see which way you want to go. Expect to need 4" x maybe 8"-14", Unibox will tell you. Maybe $15 to $30?

Hardware: You'll need cabinet feet, speaker wire, rear terminals and driver fasteners. When using wood screws to fasten drivers, the wood will often get stripped if you have to remove and insert them a number of times. For that reason, many people use machine type screws with what are called hurricane nuts. Price these out. Might be up to $30.

The Crossovers: You might try pricing out the xo at Parts Express for a speaker something like you want, say the Tarkus to give you an idea of costs. For the Tarkus xo, the 6mH inductor should have as low resistance as possible, (so a solid core, which is cheaper too) and the 125uF cap can be a non-polarized electrolytic to save you a lot of money. Otherwise, these for caps, these for inductors and these for resistors. Expect to probably pay somewhere around $150-200 if you opt for the least expensive parts and depending on how nicely the drivers you end up choosing want to play together.

Finishing: Sandpaper, Bondo, primer, paint (rollers or rattle cans), or veneer (and glue?) and clear coat? Costs can add up really quickly here. Expect $30-100?

And adding things up, it could look like this:
Amp = $150
Tools = $50?
Wood = $100
Insulation = $75
Hardware = $30
XO = $175
Finishing = $50

For a total of about $630. Just a guess at this point. Now maybe you don't worry about the finishing right now. Maybe you need no new tools. Maybe you don't include the amp. The total then will be about $380. On a $700 budget, that will leave you with $320 for the drivers which isn't bad. With a total of 8 drivers, that will average out to $40 per driver. Not exactly what you've had in mind up to this point though.

And right about now, you might want to re-think your design and acquaint yourself with the word 'compromise' Or 'patience' perhaps if you decide to wait longer to save up more money. Going with 1 woofer instead of 2 will save you in terms of driver, wood and insulation costs. Maybe finishing as well. You can still expect around 96 or 98dB at the listening position with a single with most of the woofers we've been looking at so far. Just something to think about anyways......

And hopefully, I didn't forget anything.......
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Last edited by jReave; 13th July 2018 at 12:42 AM.
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Old 13th July 2018, 01:30 AM   #267
hollowboy is offline hollowboy  Australia
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Originally Posted by jReave View Post
hollowboy's linked paper may be a little more complex than you need right now. Or maybe not. But it is looking at the effects of more than just room pressurization gain.
The simple version is just to look at the 2nd picture. The smooth line is response outside (close to an ideal simulated response), spiky blue line is response inside (what you actually hear in most systems).

room gain

Below 200 or 300Hz, real results are not like the simulation*, and the results vary when you move the speakers around, or install them in different rooms.
That's got nothing to do with how good your speakers are - it will be true for your build, and also true for a commercial equivalent that cost $50,000 for a pair.

*the exceptions being 'perfect' rooms, where the user has used some combination of:

-planning
-multiple bass sources
-room treatment
-good layout
-equalisation
-trial and error

...to get the low frequency response to be more even.
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Old 13th July 2018, 01:44 AM   #268
WillHoog is offline WillHoog  United States
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the jigsaw on amazon was $30 but routers were all in the $200 to $300 range... Also my dad has a power sander so finishing won't be a problem. Might just add $10 for a thing of black spray paint. He also has a solder.

This is a very long term project so I could easily do some work and wait till I can afford the next thing If I can't get everything for my Bday.

I also think a new keyboard can wait since it is mainly for looks, by October I should have like $150 to $200 of my money to add if needed. Of course I don't need to spend every dime I can but this could be insurance because I don't know what everything will be in the end.

Hopefully if you think it wouldn't be stupid, I would want to get to work on the box asap. If you think I should get the crossover design down before I'll do that but after the drivers are confirmed I should be able to confirm a bunch of other things in the budget.
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Old 13th July 2018, 02:12 AM   #269
WillHoog is offline WillHoog  United States
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Quote:
Originally Posted by hollowboy View Post
The simple version is just to look at the 2nd picture. The smooth line is response outside (close to an ideal simulated response), spiky blue line is response inside (what you actually hear in most systems).

room gain

Below 200 or 300Hz, real results are not like the simulation*, and the results vary when you move the speakers around, or install them in different rooms.
That's got nothing to do with how good your speakers are - it will be true for your build, and also true for a commercial equivalent that cost $50,000 for a pair.

*the exceptions being 'perfect' rooms, where the user has used some

combination of:

-planning
-multiple bass sources
-room treatment
-good layout
-equalization
-trial and error

...to get the low frequency response to be more even.
Not sure how I'm supposed to implement this into my build. I can't change the room...
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Old 13th July 2018, 03:01 AM   #270
hollowboy is offline hollowboy  Australia
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Quote:
Originally Posted by WillHoog View Post
Not sure how I'm supposed to implement this into my build. I can't change the room...
You don't

My point is that bass response will be messy in real life, no matter how much time you spend obsessing about the length of the port you use.

Measuring the finished box, and spending 20 minutes finding the best position + eq settings for it will probably give more benefit than getting the LF alignment absolutely perfect on paper.
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