Home Theater Forum and Systems banner

1 - 16 of 16 Posts

·
Registered
Joined
·
35 Posts
Discussion Starter #1
Hi everyone. Im a newbie and in the process of building my whole system from scratch. Right now I am finishing up a TV Stand/Subwoofer which I received alot of help with from everyone on here (especially Mike P.). Now I am in the designing process of making my front towers. I have purchased all of the speakers and need to know a few things. Right now I have 2 10" Polk Subs for the drivers. These were used in some PSW??? standalone subwoofers that Polk makes. I think these will work great and add even more low end with my Adire 15" TV Stand/Subwoofer. Theres a pic at the bottom of this post.

Now, as for the mids and tweets. I picked up some car audio mids and tweets that I heard and liked. They were very affordable. Keep in mind that this is a budget build. They are called C4. I need to know what you guys think of these and to make sure that they will work for my application. I plan on running 2 mids and 2 tweets per speaker. They will be run from a different amp than the 10" polks. So each speaker will be bi-amped. I also wanted to know if I can use the crossovers that came with the speakers. They are 4 ohm and my amp is very capable of running at that. Since I have 2 sets for each speaker, I can actually run them at 8 ohm. Let me know what you guys think, or if its a total waste of my time. This is all I have for the specs on the mids and tweets:

Woofer: Silver die cast aluminum basket cutting finish, black woven kavier fiber glass compound cone, rubber suround.

Tweeter: 25mm Silk dome, neodymium magnet, Aluminum housing for clarity, high frequency up to 30K Hz, low resonance at 1100 Hz.

Crossover: High quality glass fiber board, 4000 Hz frequency response 12dB/octave. Tweeter protection.

Specs:
Woofer size: 179mm
Woofer V.C. Dia: 26mm
Tweeter V.C. Dia.: 25mm
System Impedance: 4 Ohms
Power Handling (RMS): 150 watts
Power Handling (Max): 300 watts
Frequency Response: 50-30000Hz
Sensitivity: 91dB(1W/m)

This is all the specs that they come with. I chose them because they will look great in the towers. They have a bullet dustcap which makes them look more like a home speaker and the aluminum around them also makes them look nice. I did get to listen to them on a board at the shop I purchased them from and was very pleased with the sound. This is why I bought them. This and the fact that I got them for $30 a set, as the were discontinued. Please let me know your honest opinion about them.

Here are the speakers to be used:
Sub

Mid and tweet

Backside of mid
 

·
Elite Shackster , HTS Moderator Emeritus
Joined
·
2,216 Posts
Whew, where to start:

First, I hate to be the bearer of bad news, but you will most likely not be able to use the crossovers that came with the speakers. Crossovers are VERY sensitive to speaker parameters. Any deviation of driver impedance, natural rolloff, and driver resonance can make for big changes in crossover design. Simply swapping out one driver for the next, even if they're the same size and have similar impedance plots -- is a recipie for disaster. Most likely you will have a deep null or peak at the crossover frequency.

Also, crossovers aren't just for splitting the frequencies between drivers. They have baffle step compensation (to account for the bass being boosted by the baffle), impedance compensation (driver dependent), and possibly notch and shelf filters to deal with breakup modes (distortion) or weird anomalies in the response.

Now all this isn't to say you can't use the drivers you picked, but the crossover will need to be designed for them. At a minimum you will need a microphone and some measuring software (like REW).

If you are set on the drivers and the enclosure, then the only other thing is the crossover. Mount the drivers and measure them one at a time. Then you can decide on crossover frequencies and go from there.

Google "FRD Consortium" for a website that has a lot of free speaker design tools (including crossover design).

Mostly speaker design is a iterative process on every level (cabinet design, driver selection, crossover design). So you may find a lot of hurdles -- but it's a great learning experience and you may figure out a better solution along the way.

Good luck and feel free to keep asking questions. A lot of people here willing to help.
 

·
Registered
Joined
·
35 Posts
Discussion Starter #3
Well, I did like you said and downloaded all the software. I dont have a clue as to how to use it, but I will learn over time. Like I said, I am a newbie and when I entered this audio world, I had no clue as to how much there is to know. It is amazing that people know all this info. You really need to be an engineer just to make a 2 way speaker. Crazy!!! I went to public school, so I dont know if I can do this.

What would be the best way of building this speaker from my standpoint. I am not trying to win any competitions, Im just trying to build some nice looking speakers for my home on a budget and have some nice sound. Do I start by just building the encloser blindly and then build the crossover to suit? On the sub portion of the tower, Im actually copying Polks size of thier sub so that is easy. But for the mids and highs, I was just going to make them to fit inside of about 1 Cubic foot sealed.

It seems so complicated compared to cars. You would literally buy these and slap them in your doors (Maybe add some dynamatt) and they sound great.

As for the cross overs. It is way out of my league. Building a crossover is too much. I cant learn everything about everything, so Im looking to build this the easiest way without spending 5 years studying all the info needed to build a speaker. Any ideas? Since I have started this about a month ago, I have been a sponge trying to learn all the different aspects of audio. But its hard to learn when the terminology is also so hard. Its like trying to read in a different language. Granted, I have learned alot but for me to know all I should know in order to build this perfect, would take years.

So with this in mind...What do you think is the best approach to tackling this project. It doesnt have to sound as good as if one of you guys built it. I just want to start somewhere and learn along the way. Someday look at this project and laugh at myself. Thank you in advance for you help on this.
 

·
Registered
Joined
·
302 Posts
DS,
My standard advice is to research first, then buy, but that's water over the dam.

From an audiophile standpoint (and you're asking empirical audiophiles here), Anthony is giving it to you straight. However, being critical only to the extent realilty requires, as someone who was "very pleased with the sound" when they were "mounted on a board," I don't think you have the ear yet to hear what Anthony and others strive for. That's actually good news, and a very common thing; listening is a learning process.

Thus, you can dive in, characterize your drivers, load the data into that software you downloaded and design a system from scratch using drivers of your own selection - the true DIY hobby - or buy a pre-made XO that's fairly compatible with those drivers and get a working loudspeaker that will either please your ears or begin to teach them what Anthony and others' ears have learned.

There is a middle ground - building a documented design - but that's not possible unless you happen to find one that uses these drivers. It's the path I'm on ...

So, speaking as one untrained ear to another, my advice is to get a commercial XO with appropriate XO points for these drivers and make yourself some speakers. (Parts Express sells XOs, among others.) Listen to them, enjoy them, critique them, learn from them, and if the spirit moves you, use what you've learned when making your next set.

Have fun,
Frank
 

·
Premium Member
Joined
·
707 Posts
I have built quite a few speakers in my time and I would not recommend trying to design something yourself. Build something that has already been designed to get your feet wet. Then take the next 5 years of intense study of electrical/sound engineering and try your hand at designing a Xover, and realizing that most likely your first few or many tries will suck.
Here are some good and well documented designs http://www.htguide.com/forum/forumdisplay.php4?f=39 :T
 

·
Registered
Joined
·
35 Posts
Discussion Starter #6
Well this isnt a hobby that I wanted to study for five years before I build my own speakers. There must be an easier way. Like I said Im not trying my first speaker to be as good as what you guys could build but rather something I can say I built and tried and learned in the process. I do like the idea of using a design that ha s already worked but then I would want to utilize it into my own encloser. Everything that I see people building are square boxes without any creativity in the looks, just the sound. Im thinking I could take ones design and use the same airspace and porting, but spice it up a bit. This can work right? As for the one Im building, I am copying POLKs design on thier sub as far as air space and porting but I had nothing to follow on the highs and thought I could get away with what I was doing. Mabey Ill change my design of the upper half to follow someone elses design. Could someone reccomend a design that utilizes affordable components and that would use about 1 cubic foot of airspace, as I wanted to keep the design that I have if possible. Thank you.
 

·
Registered
Joined
·
1,582 Posts
Well this isnt a hobby that I wanted to study for five years before I build my own speakers. There must be an easier way. Like I said Im not trying my first speaker to be as good as what you guys could build but rather something I can say I built and tried and learned in the process. I do like the idea of using a design that ha s already worked but then I would want to utilize it into my own encloser. Everything that I see people building are square boxes without any creativity in the looks, just the sound. Im thinking I could take ones design and use the same airspace and porting, but spice it up a bit. This can work right? As for the one Im building, I am copying POLKs design on thier sub as far as air space and porting but I had nothing to follow on the highs and thought I could get away with what I was doing. Mabey Ill change my design of the upper half to follow someone elses design. Could someone reccomend a design that utilizes affordable components and that would use about 1 cubic foot of airspace, as I wanted to keep the design that I have if possible. Thank you.
I can totally understand and appreciate what you're saying. And there are easier ways -- if you don't mind spending the $$. The hardest part of designing a speaker is to get the crossover designed. It's 3 parts technical, 3 parts art, 3 parts black magic and another 3 parts luck. A "cheater" way to handle the crossover is to go active. No need to design a circuit, you can choose whatever you want. And, if you get something like the Behringer DCX2496, you can even experiment with different flavors (Bessel v. Linkwitz/Riley) and different orders (from first order to an eighth). On top of that, you can adjust the timing, so you can get all of your drivers time aligned and in phase -- something that can't be done with a passive crossover itself. On top of all that, it's supposed to be sonically superior. The downside is the cost - you need the crossover itself plus an amp for each driver. So, for a typical two way design, you'd need four channels of amplification. In a three way design, that would mean 6 channels.

As for the square box.. shapes make a difference in the final sound of a speaker. They're also easier to make.. but making something more exotic can be done too.

Finally, I'd take a look at the designs on Zaph Audio. I've never heard them, but he's got a decent following and has several inexpensive designs you can take a crack at.

Good luck.

JCD
 

·
Registered
Joined
·
35 Posts
Discussion Starter #8
I can totally understand and appreciate what you're saying. And there are easier ways -- if you don't mind spending the $$. The hardest part of designing a speaker is to get the crossover designed. It's 3 parts technical, 3 parts art, 3 parts black magic and another 3 parts luck. A "cheater" way to handle the crossover is to go active. No need to design a circuit, you can choose whatever you want. And, if you get something like the Behringer DCX2496, you can even experiment with different flavors (Bessel v. Linkwitz/Riley) and different orders (from first order to an eighth). On top of that, you can adjust the timing, so you can get all of your drivers time aligned and in phase -- something that can't be done with a passive crossover itself. On top of all that, it's supposed to be sonically superior. The downside is the cost - you need the crossover itself plus an amp for each driver. So, for a typical two way design, you'd need four channels of amplification. In a three way design, that would mean 6 channels.

As for the square box.. shapes make a difference in the final sound of a speaker. They're also easier to make.. but making something more exotic can be done too.

Finally, I'd take a look at the designs on Zaph Audio. I've never heard them, but he's got a decent following and has several inexpensive designs you can take a crack at.

Good luck.

JCD
Thank you for your response. I love your idea about the Behringer. Is it posible to use this device to find out what kind of passive crossover I will need? I dont mind spending the money on it if I could use it this way. In other words, If I dial in the speaker to what I need, you will be able to see what all the settings are and build a passive crossover based on that. Am I dreaming or is this possible? As for the shape of the box, everything I have read is that the worst design for an encloser is square. So building something uniqe should benifit the system. I read that the perfect encloser is a sphere. Something about the wavelength being bounced around inside and that a square or rectangle is the worst because it bounces off only 2 directions. Once again, I am a newbie so this could all be Hogwash. Let me know whatcha think. All input is appreciated, as I am trying to be a sponge with all of it.
 

·
Registered
Joined
·
39 Posts
Hey there! Don't be put off designing your own crossovers. You can pick up a cheap spl meter in the states I'm sure (ou guys seem to be spoilt for choice!) Download a free tone generator. Get a bit of paper and note down the tweeter response to a bit below where you think you'd like to crossover. Then using an online crossover calculator pick a capacitor (a few buck max, don't bother getting expensive ones while your trialling them) add it before the tweeter then go through the tones and spl again. You'll be able to use the online calculator again once you have the results to see what the impedance actually is at the point youve chosen. Next, use the nominal impedance of the mid, pick a coil and now running the tweeter with it's cap and the mid with it's coil do a sweep, it will either peak or dip at the xo point and that'll tell you where to go from there.

People here might heckle me for supporting this approach and the results it will yeild but hey, we all start somewhere and this is a very cheap and accessable way to start on your way designing stuff. It sounds like your pretty daunted by the level of work others put into their setups, don't worry about it. In fact, forget about it. Get your hands dirty for not much money and thats the first step done, don't be too concerned with how you feel about step 34,567 at this stage.

If your copying the sub box the subs came in then sweet as. chuck that mid into something not too small, whatever the std box a program like winISD spits out and away you go.

Don't be daunted, looking forward to seeing your setup running!

Brian
 

·
Registered
Joined
·
35 Posts
Discussion Starter #10
Hey there! Don't be put off designing your own crossovers. You can pick up a cheap spl meter in the states I'm sure (ou guys seem to be spoilt for choice!) Download a free tone generator. Get a bit of paper and note down the tweeter response to a bit below where you think you'd like to crossover. Then using an online crossover calculator pick a capacitor (a few buck max, don't bother getting expensive ones while your trialling them) add it before the tweeter then go through the tones and spl again. You'll be able to use the online calculator again once you have the results to see what the impedance actually is at the point youve chosen. Next, use the nominal impedance of the mid, pick a coil and now running the tweeter with it's cap and the mid with it's coil do a sweep, it will either peak or dip at the xo point and that'll tell you where to go from there.

People here might heckle me for supporting this approach and the results it will yeild but hey, we all start somewhere and this is a very cheap and accessable way to start on your way designing stuff. It sounds like your pretty daunted by the level of work others put into their setups, don't worry about it. In fact, forget about it. Get your hands dirty for not much money and thats the first step done, don't be too concerned with how you feel about step 34,567 at this stage.

If your copying the sub box the subs came in then sweet as. chuck that mid into something not too small, whatever the std box a program like winISD spits out and away you go.

Don't be daunted, looking forward to seeing your setup running!

Brian
Thank you for the response. I think you understand where Im at in the learning process. I like what you are saying, only a couple of questions. Like I said, Im a newbie and this may sound really stupid to you guys, but I have to ask if I want to learn. I dont know what you mean by checking the impedance and some of the other things you said. I was always under the impession that impedance was a measure of resistance and that was decieded by the speaker Ie: 4 Ohms

I know this sounds stupid, but could you break it down even more for me so I understand it better. You guys are probably thinking (This guy shouldn't even touch a speaker) but I really do want to learn and Im starting from below the bottom. I know this is the place to learn because Ive seen some posts that just amaze me when I read them. Like these people should be building Top Secret Unmanned Aircraft for the military, not speakers. But if you would, step down to my level and show me the ropes.

I do have another question. Can I use a crossover out of a prebuilt speaker. I bought a crossover from a Infinity center channel and I was going to build one very similer to the infinity. I would not have the same brand of drivers, but it would have the same size. I know that it wouldnt be ideal, but would it be usable? Or is it just not possible to try and do that.

I purchased a whole bunch of cheap speakers from PE the week to practice with. They were on sale. (SpeakerCraft 5-1/4" Shielded Aluminum MidBass for $12 ea) I would like to mabye make a line array with 4 of them with 1 tweeter for a center channel or a tower speaker. Once again, I dont know. I just wanted to build something to learn. Do you guys have any sugestions of how I could make something out of these to learn what Im doing.

Again, thank you guys for the help. I know that Im a pain in the ****.
 

·
Registered
Joined
·
39 Posts
First off I have to make it clear until recently I didn't know there were forums and online sources for speaker building so my experience is very hands on/trial and error. Feel free to use whatever crossovers you have around on your speakers but make sure you only use a high pass not a low pass on the tweeters. You'll quickly cook a tweeter with too much low frequency. As they're designed for different speakers the chances of them working how you want is close to zero but for sure hook them up and see what they do, pull them apart for components or whatever you like.

What is it about the impedence you need cleared up? I think I understand the question, your 4 ohm speaker isn't 4 Ohms at any frequency. It has a NOMINAL impedance of 4 Ohms, someone will pipe in with the exact meaning but that is roughly the average/mean impedance. This impedance normally peaks around the resonant frequency and then rises again more slowly with frequency. Things like piezo speakers are exceptions and again, anyone that can add to this please feel free to add your bit. Anyway, the resistance of your speaker (actual not the nominal) at a given frequency will change the effect of a crossover companent at that frequency, so two speakers with difference impedance will cross at a different frequency with the same component.

Have fun. Play, enjoy!
 

·
Registered
Joined
·
39 Posts
here is an impedance graph from a speaker I want to use as the mid for my next build

The are 8 Ohm speakers but as you can see there is a great range of loads across the usable frequency of this speaker
 

·
Elite Shackster , HTS Moderator Emeritus
Joined
·
2,216 Posts
Yeah, for a first-timer, a kit or active would be the way to go. I don't like active speakers, because I want my end product to be portable (i.e. just move it to any system and play, no extra wires, or plugs, etc). But I have used active crossovers to help in picking a crossover point, they are useful in that regard.

The downside is cost and if you have a problematic driver that needs a notch filter or shelving filter to even out some irregularity, then you're either talking a more expensive active crossover, or you have to use passive components as well. Can get pretty complicated.

As for testing equipment -- at the least, get a radio shack SPL meter and the wires to hook it into a computer. Then you can use Room EQ Wizard (REW) to take measurements and see how you are doing. A better choice would be the Behringer ECM8000, but you also need a preamp for that. Search in the REW forum here for setup tips and tricks.

But test equipment is a must, because there will be some trial and error to the tuning, even if you go with an active crossover.

Good luck.
 

·
Registered
Joined
·
35 Posts
Discussion Starter #14
Yeah, for a first-timer, a kit or active would be the way to go. I don't like active speakers, because I want my end product to be portable (i.e. just move it to any system and play, no extra wires, or plugs, etc). But I have used active crossovers to help in picking a crossover point, they are useful in that regard.

The downside is cost and if you have a problematic driver that needs a notch filter or shelving filter to even out some irregularity, then you're either talking a more expensive active crossover, or you have to use passive components as well. Can get pretty complicated.

As for testing equipment -- at the least, get a radio shack SPL meter and the wires to hook it into a computer. Then you can use Room EQ Wizard (REW) to take measurements and see how you are doing. A better choice would be the Behringer ECM8000, but you also need a preamp for that. Search in the REW forum here for setup tips and tricks.

But test equipment is a must, because there will be some trial and error to the tuning, even if you go with an active crossover.

Good luck.
Funny you say that. I just picked up a Radio Shack SPL meter last night. It is " Digital Sound Level Meter 33-2055" I hope this is the one I need. Some guy had it for sale locally for $25 and it is basiclly new. Ill get to playing around with it and the software once I figure out how to hook it up and use the software. Im reading all about that now. I also purchased some books on ebay, so that should help to. This is very overwhelming trying to learn all this stuff but well worth it. I appreciate all the help from everyone. You will probably being seeing alot of threads from me asking questions. I hope I dont get on everyones nerves asking stupid questions, but its the only way Ill learn. Thanks for the help.
 

·
Elite Shackster , HTS Moderator Emeritus
Joined
·
2,216 Posts
No problem. Many people like the analog better than the digital because you can see the intermediate steps (not just a rounded whole number), but I believe the circuitry is the same in both. there are some calibration files for the radio shack meters here on the Shack and elsewhere on the internet.

I will warn you, the RS meter is not that good for high octave stuff, but with correction will get you close. If you find yourself latching onto this hobby hard-core, then I would upgrade the Behringer or other dedicated full range mic.

Don't worry, though, you will still need an SPL meter to help calibrate measurement software, so your money was well spent.
 

·
Premium Member
Joined
·
707 Posts
On the Xover you have, the short answer is no you cannot use it with different drivers or a different box. These are factors that are supposed be calculated into the Xover for that speaker. On the box, you do not have to use a square, we build them that way cause its easier.
 
1 - 16 of 16 Posts
Top