# Speaker project ideea...some suggestions



## Guest (Oct 23, 2007)

Hello everyone i am new to the forum. 
This is my first DIY speaker project, i did a subwoofer before, but no multidrivers..tower speakers. i had this ideea in mind, but i don't know if it will work. I already have the woofer drivers, 2 Pioneer 80 watts RMS/31-7,000 Hz/8 ohms link here. My goal is to make a speaker set that sounds great on high and low frequencies, and have great sound quality. What do you guys think about the project, and what crossover, mids and tweeter drivers may I use?


thanx in advance.


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## Anthony (Oct 5, 2006)

Welcome to the Shack!

Interesting design there, but I will caution you: don't finalize the cabinet design until you pick the drivers. 

You said you already have the woofers, so that's a good start. What you are going to need is some midrange and tweeter drivers that match the efficiency of the woofers. Since you are using two woofers, they will be more efficient (I think it's 3dB for every doubling of drivers), so if they are 92dB efficient, two of them will be 95dB efficient. 

Depending on which midrange you choose, you may only need two, or you may need four. The symmetrical arrangement you have there is good for vertical dispersion pattern (I like MTM arrangements). Always try to keep the MTM as tight as possible (vertically) to avoid comb filtering effects.

Again, try to match the tweeter sensitivity to that of the midranges and woofers. 

Now as for cabinet volumes and port sizing and such, I am at a loss. I've done one sealed speaker and one open baffle speaker, so I am no expert here. However there are others around here that can probably help.

I would suggest reading up on some of the projects here and over at DIYaudio.com. Also check out Zaphaudio.com for some great insight and testing of speaker drivers.

As for calculation tools, you can go free or pay for them. Two free options are the FRD Consortium (http://www.pvconsultants.com/audio/frdgroup.htm) or Speaker Workshop (http://www.audua.com/) Both have a steep learning curve, but once you get the hang of them, you can prototype driver layouts and crossovers pretty quick.

Parts Express has several software packages for purchase that are a lot easier to use (better support and manuals), however, you pay for that. I haven't used them, but search around, a lot of people rave about some of those packages.

Best of luck and keep us posted. Hopefully more people will chime in on help with your design.

Anthony


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## Geoff St. Germain (Dec 18, 2006)

Have you done any crossover design before? How much work are you willing to put into this project? Designing a crossover properly can be a difficult task and can be made more difficult based on driver selection. I'm not trying to discourage you, but if this is something that you want to whip together pretty quickly, then IMO you are better off going with a completed design. If you are willing to do some trial and error and/or a lot of simulation then by all means come up with your own design from scratch. It will require quite a bit of prerequisite reading and a fair bit of time designing.


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## Guest (Oct 23, 2007)

You are very much better off going with a simple design for your first project. Try a 2-way with low order filters. If you really, really want to build something big, see if there are any tried and true designs already out there, that may save you alot of headache. The more complicated you get, the more chances are something won't be right. I highly suggest buying a copy of the loudspeaker design cookbook by Vance Dickason and reading as much as you can first, and if you can afford it, buy some enclosure and crossover modeling programs...


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## Doug Plumb (Mar 16, 2007)

My suggestion would be to go active. RPlusD software makes active speaker crossover tuning easy and accurate. A good passive Xover is difficult to build - the simple explanations assume theoretically ideal drivers - something that doesn't exist. An active Xover is much easier. Behringer supplies the DCX 2496.

This way you can replace drivers in your speakers with better ones as they come along. Homemade speaker builders have the big advantage of being able to put large radii around the front baffle - this cuts diffraction.

This disadvantage of active speakers is that you require one power amp for each "way" but these can be found for cheap.


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## Doug Plumb (Mar 16, 2007)

Read the chapter on active DSP Xovers in my maunual downloadable from my site and consider it. This approach doesn't get as much attention as it should.


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## Guest (Oct 23, 2007)

for the crossover, i am very good in soldering and making electrical circuits...so i can do it myself. i think one woofer by speaker is enough and maybe only 2 midranges as well. i am willing to put some work in the project, time is not a problem. i will start some calculation and see what drivers go better and maybe simplify the project a bit. thanks again.


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## Doug Plumb (Mar 16, 2007)

I don't think many people can make a great passive Xover, myself, I have a degree in EE with advanced coursework in passive networks. I couldn't do it without writing a passive simulator first.

You can make a great Xover with a DSP Xover.


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## Guest (Oct 23, 2007)

well yes, i mean if i would have already a scheme, and just "put together the pieces", i can't make it all myself, that needs some speciality in the domain.


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## JCD (Apr 20, 2006)

First off, welcome to the Shack!

Now on to the "stuff".. I'll just throw out some general stuff:


Building a passive crossover for a 2 way system is supposed to be really really really hard. Going to a three way is even more difficult.. by alot. Not that it can't be done with a lot of patience, testing, money, etc, but to do it right is just difficult. Going with an active crossover will simplify this process a LOT. Of course, it will add cost as you will have to buy more amps and the crossover itself.
If you haven't, I'd suggest buying Vance Dickason's *The Loudspeaker Design Cookbook*. The current release is 7, but you can get the 6th for cheap here.
If you go with a three way system, I'd look for at least 1 octave overlap between the drivers. In other words, if the freq range for the woofer is 31hz-7000hz, I'd want a mid that was good from at least 3500hz to whatever. Even more overlap is better -- I've heard that a 2 octave overlap should be the rule of thumb, so you'd want a mid that could go at down to at least 1750hz. 
The idea about waiting on the cabinet design until you pick your drivers is a good one -- the ideal enclosure dimensions are dependent on the drivers chosen.

That's all I've got for now. If I think of anything further, I'll drop another post.

Good luck and welcome to the fray!

JCD


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## Doug Plumb (Mar 16, 2007)

The beauty of an active system is that you can use an 8th order Xover - so you need less than anoctave of overlap. Richard Small in his Xover papers suggests about two octaves of overlap for 1st order Xovers, 2nd order requires about 1, 4th order requires about a half and so on - I may be off a little but this represents the general idea.

For a 3 way you should use steep filters - for a two way it may not be a good idea therefore with actives a 3 way is easier. You don't get the radiation pattern differences between the drivers that a 2 way will give you. Ie for a 12 inch and 4 inch crossed over at 500 Hz both drivers radiate sound into the room approximately the same because the driver circumference is less than the wavelength of sound at or near the Xover.


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## BoomieMCT (Dec 11, 2006)

axlstyle said:


> for the crossover, i am very good in soldering and making electrical circuits...so i can do it myself. i think one woofer by speaker is enough and maybe only 2 midranges as well. i am willing to put some work in the project, time is not a problem. i will start some calculation and see what drivers go better and maybe simplify the project a bit. thanks again.


It isn't the soldering that is hard - it is the design. Designing passive crossovers is tricky, but by no means impossible. I'd agree with JCD and suggest looking at Vance Dickason's book as well as searching for _Passive Crossover Designer _from the FRD Consortium online (free software). As long as you don't mind some testing and are comfortable not getting it exactly right the first time you should be okay.


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## Guest (Oct 24, 2007)

wow. i realise i know so little about crossovers. better see if i can find an already designed 3 way, good tought that i didn't brought the mids and tweeter yet. i will also try to calculate the frequencies with the Passive Crossover Designer tool, i'll take some random drivers and see what i get. but there are still some chinese parts that i can't get:dumbcrazy:


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## Anthony (Oct 5, 2006)

Yeah, I agree that crossover design isn't super simple, but it's by no means impossible.

I followed the instructions on the FRD Consortium for their passive crossover designer and designed a three way that worked almost perfect on the first cut. It took a while to input all the drivers, pick the right frequencies, tweak the component values to things I could actually buy (4.5uF cap is not available, 4.7uF is -- things like that). 

I was actually shocked the first cut was as accurate to the simulation as it was. So if you don't mind playing around with the software for a few hours, you can design your own.

Three way crossovers do get expensive, though. Using decent parts (but not top-of-the-line) from Parts Express, the crossovers for each speaker are $60+, but that's still cheaper than getting a Behringer digital crossover and two extra amp channels.

The downside is that changing the design is more difficult (I hate desoldering) and that 4th order slopes are about as high as you will get without serious inductor coupling issues (they need to be separated). Not to mention the added cost of the extra components.

don't get me wrong, I'm interested in active crossovers as well, it's just not always the ultimate solution.


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## danielbarbu (Jul 14, 2007)

Hi there !

I found a passive crossover scheme for you but i know that you gonna say like always ''that sucks'' or something like that because i know you.I hope that helps. ''Moldovean imputit )''










L1 = 3.3 mH 18 ga. air core
L2 = 3.3 mH 19 ga. air core
L3 = .51 mH 19 ga. air core
L4 = .51 mH 19 ga. air core 

C1 = 22 µf NPE 100v + 4 µf NPE 100v
C2 = 22 µf NPE 100v + 4 µf mylar 100v
C3 = 4 µf NPE 100v
C4 = 4 µf mylar 100v 

R1 = R2 = 10 Ω 10 w
Cc1 = 22 µf NPE 100v
Cc2 = 4µf NPE 100v 



OR you can buy this : https://www.addison-electronique.com/catalog/product_info.php?cPath=1_1015&products_id=10316&osCsid=765b3ceed0400aac9e7275ff66c37d3c


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## Doug Plumb (Mar 16, 2007)

R1 should match the voice coil resistance of the driver being used. Cc1 is calculated from the voice coil resistance and its inductance. All other values are dependent on voice coil resistance. The above network is a shot in the dark for any given random driver set and nothing more.

Crossovers need to be matched to the drivers used and the front baffle used. One size does not fit all.


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## BoomieMCT (Dec 11, 2006)

Doug Plumb said:


> Crossovers need to be matched to the drivers used and the front baffle used. One size does not fit all.


+1, Ding ding ding! General rules of thumb will get you close but there is a very good chance of having noticable errors. The best thing to do would be to test the drivers you get and design from there. Second best would be to find FR and impedence (with phase) graphs from a repituable manufacturer. In general you shouldn't design off T-S parameters alone.


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## Guest (Oct 24, 2007)

that scheme is just a "sample" of a crossover, the components values don't match with any drivers. 
i just have one issue with the passive crossover designer, the one in excel. how can i load the drivers, or are there any samples of drivers that i can use?


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## Doug Plumb (Mar 16, 2007)

The thing is that really really good commercial crossovers inside speakers do not have a layout that is anything like the standard layouts. This is because they account for real world drivers.


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## Guest (Oct 24, 2007)

yep. exactly ! i just bought a one-way subwoofer crossover (120hz, 400w, 12dB/oct)...and there are no layouts on the components. i tought i could make another one for cheaper just by buying the components....but i can't:rolleyesno:
it's nice, were i live in montreal-canada, there's an electronic shop, like partsexpress, but much cheaper, and with good products, like the sub crossover that i got for 10 bucs.


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## Doug Plumb (Mar 16, 2007)

Canadian eh ? Me too.


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## F1 fan (Jul 6, 2006)

I agree wholeheartedly with post #5,Im using active crossovers because I know I could not achieve anything near the same performance if I had tried to design my own passives.

Doug with your RPlusD you have placed a wonderful tool in the hands of DIYers.With it and the DCX 2496 and some good drivers one could make themselves a very nice active system.


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## Guest (Oct 25, 2007)

axlstyle said:


> yep. exactly ! i just bought a one-way subwoofer crossover (120hz, 400w, 12dB/oct)...and there are no layouts on the components. i tought i could make another one for cheaper just by buying the components....but i can't:rolleyesno:
> it's nice, were i live in montreal-canada, there's an electronic shop, like partsexpress, but much cheaper, and with good products, like the sub crossover that i got for 10 bucs.


Just a note, in this field, you often get what you pay for. a 10$ crossover will sound... well, 10$.
If you ever decide to go passive on that future crossover of yours, 
better get quality parts to get your "great sound quality".
Ive worked with both cheap and expensive passive crossovers, and the difference in rendering is *stellar*. 
In canada, I suggest this place ---> www.solen.ca 
They can *design *a good passive crossover for your drivers, and sell you the parts, but it will cost you more, as you should expect. If your project ends up using good drivers, it's worth it IMHO.


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## Owen Bartley (Oct 18, 2006)

Axl, I'd agree with a few of the posts that picking up the Loudspeaker Design Cookbook would be a great investment, especially the cheap version. I ordered it when I wanted to start my own speaker project, and I learned a TON while reading it (I read through it all before I started anything, and mostly what I learned was how little I knew and understood about drivers and crossovers and their interaction). But I ended up choosing a design from the book to build as my first non-sub project, and the pre-designed crossover worked great. You can check the link to my DIY rear surround in my sig if you're interested in the construction.

I know it can be a bit discouraging when you have grand ideas in mind, and then find that your original plans won't work, but don't let it get you down, just use it as an excuse to learn a little bit more and take a look at some of the other already designed speaker projects on this and other forums. There have been some great ones, both big and small, and I bet you'll find one that interests you.


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## 1Michael (Nov 2, 2006)

I have built several speakers and many subwoofers over the last several years and I would not even consider designing a speaker for my first project or any other project:no: If you want a good speaker system that has been tried and tested check out these designs. Designing a crossover is harder than people would lead you to believe:coocoo:

http://www.htguide.com/forum/forumdisplay.php4?f=39


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## Anthony (Oct 5, 2006)

My first speakers were Adire kits, so the design burden was taken off of me. My current open baffle project is my first "ground up" speaker, although I've tested a lot of drivers and designs in the process.

BoomieMCT has made about 7 "from scratch" speaker designs, so hopefully he'll chime in more on crossover design here.

there is no magic in it, you just need to be prepared to take one of two approaches:
1) Plan, plan, plan, test, tweak, and (hopefully) done
OR
2) Plan, test, replan, test, replan, test, tweak, and done.

Unfortunately you can't just wire up any driver with any crossover components and be done. There's definitely a trial and error approach to it, or at least a measure-model-build then trial and error to get it right. I happen to like the simulation aspect of it, I know BoomieMCT likes the trial and error aspect (we live close by, so we've both helped on projects).

So if you're up for the adventure -- go for it. Otherwise, there's no shame in starting with a kit and seeing how it takes off.


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## BoomieMCT (Dec 11, 2006)

Yeah, what Anthony said!

I've said it before and I'll say it again, making your own crossovers is definately not impossible. It does take some understanding of the principles involved as well as the patience to do some trial and error. You have to be willing to not get the answer on the first try. It also helps to do some simple test builds first to get your knowledge base and experience up. I've built many speakers I didn't need just because I wanted to test out a concept to understand it better.

I'd say the minimum equipment is some kind of simulation program to get started (I tend to use FRD Consortium products but there are others) and some kind of microphone to test your results. I started with a Radioshack SPL meter which I used to take manual measurements, now I have a Behringer mike that plugs into my computer and I use Room EQ wizard. Adding simple acoustic treatments to your test area helps a lot too. I make a habit of buying extra crossover componants every time I make a parts order so I have stuff on hand to play around with. Contrary to what Anthony said I do model designs on the computer before building them, I just put a lot more faith (and enjoyment) in the testing and evaluation process. I've also learned to trust what makes my ear happy more than what comes out in a FR.

For people who don't want to commit the time for testing and evaluation and money for testing gear (or don't have the right mindset to enjoy the process) I'd suggest kits or using other's plans.


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