3-Way L-Ported Speaker System

[GraysonPeddie]

Hi. I'm Grayson Peddie and I'm new to building speakers. I plan to build a 3-way speaker system (with the help of my dad when it comes to working with wood). Let me start off that my budget will be $150 or less per speaker (it'd be great if I can get below $100, but I don't think it's possible, due to the rest of the paragraph that I'm about to mention). My goal is to build two speakers that are >90 dB efficient (SPL) and that I want to get between 25 Hz to 30 Hz for low end and for high end, above 20 kHz. What I could do is use a horn that produces frequency responses up to 30 Hz (40 Hz is low-priority, even if I want to get a feel for ultra-sonic high frequencies above 20Hz). It will be ported, and I'm hoping to tune a box to maybe 25 Hz. The size of the speaker should be no larget than approx. 3 cubic feet, as I plan to use Accousta-Stuf PolyFill dampining material, which comes out to be about 1.5 pounds per speaker, but the volume of the speaker enclosure will go down as I add drivers, a port, crossover, and a speaker terminal. So, the speaker dimensions I am targeting is 13.75" in width and depth, and 27.5" in height (I'm "math-o-holic" ). The reason for extra inches below the woofer is to allow for a resonance (Fs) to be tuned a bit lower). The first and second braces will be located in height of 4" (first) and 6" (second), respectively. The port will be placed between first and second brace. Speaking of ports, at about 8" from front to back, there will be an "elbow" that will rotate the port downward. From there, the port continues down, until it gets to the bottom of the enclosure, but about 5"-6" away from the inner enclosure, so that the air can reach easily through the port. Of course, since the outer port will be located a few inches above the woofer and that the port is 17" long, I don't think this will be the problem. As for tweeter, I plan to use a horn. I thought it'd be good, as I wanted to have frequency response up to 30 kHz, but 40 or higher is not my priority, even when it comes to experiencing ultra-sonic waves (I think our human brains can interpret frequencies above 20kHz, even though we can't hear them). Below the horn will be a midrange and the port (midrange<->port for the left speaker and port<->midrange for the right speaker), and below that will be the woofer. Finishes for the speakers will not be included in my budget.

With that out of the way, let's get in with the parts, shall we?

295-315: Dayton DC250-8 10" Classic Woofer
280-062: Goldwood 3" x 7" Wide Dispersion Piezo Horn Mid/Tweeter
280-020: Pioneer B11EC80-02F 5-1/4" Cup Midrange
268-352: Precision Port 4" Flared Port Tube Kit (With an elbow and a coupler allowing me to bend a port to a 90 degree angle.)
260-330: Acousta-Stuf Polyfill 5 lb. Bag
260-150: Dayton XO3W-375/3K 3-Way Crossover 375/3,000 Hz
260-302: Gold Plated Speaker Terminal

(These xxx-xxx are Parts Express part numbers. Sorry! Can't post links... *sigh* )

I really wish there's a cheaper crossover with 375/3,000 kHz, but it seems this is the only one available at Parts Express. But then, that's just quality. I could say the same for the woofer ($23 is good for me), but as for midrange, I could shave about 3-4 dB of SPL off, but that's the only speaker that I saw with a low Fs of--I think 320 Hz as per the frequency response between 320-6,000 Hz. Having a crossover point of 375 Hz will allow the woofer to focus on low-midbass performance.

Anyway, what do you think? Any recommendations that you have?

 

[TLS Guy]

Sorry to blow your bubble, but that speaker will be a complete mess. Yes, a waste of you and your father's time.

You need to walk before you can run. This is your first speaker project, and you are starting with a three way.

First you need to educate yourself a lot more, before starting out. You need to understand the Thiel/Small driver parameters and how they relate to the type of enclosure that driver is best suited to. You then need to know how the driver parameters determine box volume and tuning.

You need to understand the principles of sound cabinet construction.

You can not use generic crossovers. Crossovers have to be designed precisely and uniquely for the drivers involved. Three way crossovers are particularly tough, because of driver overlap and band pass gain. The phase and group delay problems are also more problematic.

I suggest you either start by building kit with a good reputation, or educate yourself intensively, and try and design a two way speaker with the guidance of an experienced designer and builder.

Speaker building is a great endeavor, and I encourage all who want, to attempt the task. However I don't want you to get discouraged by starting a project that will fail lamentably.

 

[GraysonPeddie]

Okay. Is there a non-pre-finished kit? I'm not looking forward to spending >$100 for a pre-finished kit from Parts Express.

I will try to stress myself and elaborate intensively, but time is no problem for me. From now on, I'm gonna have to downsize the speaker, which means sacrificing low frequency response, and build a two-way speaker from there.

I really wanted to make a less-than-$150 per speaker sound like a $500-$1000 speaker...

...and building my own crossover? I don't have the skills to do that! I just want to build my own speakers for fun!!

 

[TLS Guy]

Okay. Is there a non-pre-finished kit? I'm not looking forward to spending >$100 for a pre-finished kit from Parts Express.

I will try to stress myself and elaborate intensively, but time is no problem for me. From now on, I'm gonna have to downsize the speaker, which means sacrificing low frequency response, and build a two-way speaker from there.

I really wanted to make a less-than-$150 per speaker sound like a $500-$1000 speaker...

I don't think you could build a decent set of speakers for that kind of money. If you use a kit you will need to save and double the budget. At your price you are at the very bottom end of the market. The Usher 701 looks good value for money.

http://www.partsexpress.com/webpage.cfm?webpage_id=3&CAT_ID=48&ObjectGroup_ID=769

Here are Madisounds offerings.

http://www.madisound.com/about/kits.php

Now you are a young man. You have professed patience, which is a great virtue.

My advice is to spend some time and money on books so you understand the physics behind speaker design. This may well help you in your career.

Here are some books to choose from. I would especially recommend Vance Dickerson's loudspeaker Cook Book and or Bullock on boxes for starters.

We all had to start somewhere, but starting right is crucial. Putting a lot of cash and hard work into a failure is very discouraging.

Educate yourself and plan a project you think you can accomplish. Don't go out and buy junk at a big box store.

Stay in touch there will be myself and others along the way to help advise and guide. I have found however if there is not some knowledge of the fundamental principles involved, then it ends up being frustrating all the way round.

I am working up a project that l looks very promising, that should have a cost of around $200 per speaker for drivers and crossover components. But I will have to build and carefully evaluate them first before persuading someone else to build them. You can not cookie cut fine speakers.

 

[GraysonPeddie]

Okay. I looked at the kits from Parts Express (the link you provided above) and I didn't have the soldering skills to build a crossover for that.

Thanks anyway.

 

[TLS Guy]

Okay. I looked at the kits from Parts Express (the link you provided above) and I didn't have the soldering skills to build a crossover for that.

Thanks anyway.

You are a young man. Don't end it there. We are all challenged to become skillful people and dedicate ourselves to life long leaning. For heaven sakes start leaning skills, and the more the better. That is the way to an interesting life and more likely than not financial security. If you don't start picking up skills now and adding them through out life, you will be just about unemployable in no time.

 

[GraysonPeddie]

Okay, I think I'll have to start with a crossover from there (soldering skills).

I have cheap speakers that are constructed with metal-plastic (from a $150 600w KOSS receiver/DVD (with noisy fans and distractedly blue light running across the DVD tray); I just moved to a Sony STR-DE898 during Christmas 2005) that I really need to replace pretty soon (only the front two speakers and later on, the center speaker).

My goal (from the start) is to have a lot of fun building speakers without worrying about building a crossover. After I do that, I can dive deeper into building a crossover for future projects. But then my specifications that I intend to meet turns out to be a direct failure right off the bat, and it's very discouraging to me!

 

[TLS Guy]

Okay, I think I'll have to start with a crossover from there (soldering skills).

I have cheap speakers that are constructed with metal-plastic (from a $150 600w KOSS receiver/DVD (with noisy fans and distractedly blue light running across the DVD tray); I just moved to a Sony STR-DE898 during Christmas 2005) that I really need to replace pretty soon (only the front two speakers and later on, the center speaker).

My goal (from the start) is to have a lot of fun building speakers without worrying about building a crossover. After I do that, I can dive deeper into building a crossover for future projects. But then my specifications that I intend to meet turns out to be a direct failure right off the bat, and it's very discouraging to me!

My father had a great few words of wisdom for us children. "Don't will the ends without the means."

Now every speakers has a roll off at both ends, called the order of roll off and they often change orders during roll off. Crossovers have to have roll off such that the outputs of the two speakers at crossover sum to flat. If it does not, and it will never happen by chance, then the speaker is a dog. The crossover is the very heart of the speaker. Also the drivers almost always have different sensitivities, so usually there has to be an L-pad at the high pass crossover output. You will need soldering skills for that.

Now settle down. You have the impatience of youth. Take the time to educate and learn the required skills. Then you will build something to be proud of. If you don't want to learn we can't help. I know one thing about you already. It is essential for you to start acquiring more knowledge and skills than you posses now. This is a good place to start, because it obviously interests you.

Now soldering is a very easy skill to acquire. You can read about it, but I would see if you can find a local service tech to teach you. Skillful people I have found, are only too willing to pass on their knowledge and skills as a rule.

When I bought this lake home 9 years ago. I felt I needed a couple of antique tractors to keep the place. I had never owned a welder. I had a local farmer who was the husband of one of our nurses teach me. I knew him to be a highly skilled craftsmen. He taught me well and I consider myself to be a competent welder. I have picked up a lot of other skills that way. Be enthusiastic, courteous and highly appreciative, and you will be surprised how much time skilled people will put in to make sure you do it right.

There is absolutely no pride or pleasure to be derived from making a dog's dinner of anything.

 

[adwilk]

I dont want to interrupt you're conversation...but...

If somebody said they wanted to learn to play the guitar but didnt care to learn the chords... What would you say?

Speaker building is not just building a box and throwing some drivers in the holes and making noise. You're design has many flaws but isnt a horrible foundation.

IE, horn loaded drivers are very sensitive and while they do a great job on the high end, work really well crossed over a little lower than traditional dome tweeters to take some of the work off the midrange. Obviously a custom xover is necessary here.

There are numerous resources available that will give some insight on designing the best possible speaker for your budget. Based on your previous equipment, it wouldnt take much to be an improvement. DIY is a great option.

The Dayton BR-1 is an expensive kit that gets your hands dirty on the soldering issue and turns out to be a pretty good sounding speaker. Will probably blow away your current gear and i'll think you'll be surprised by its range.

 

[GraysonPeddie]

horn loaded drivers are very sensitive and while they do a great job on the high end, work really well crossed over a little lower than traditional dome tweeters to take some of the work off the midrange. Obviously a custom xover is necessary here.

Horn tweeters! That's the answer I'm looking for.

The Dayton BR-1 is an expensive kit that gets your hands dirty on the soldering issue and turns out to be a pretty good sounding speaker. Will probably blow away your current gear and i'll think you'll be surprised by its range.

I will be missing a bit of low-end, as I like the speakers to perform at lower frequencies below 40Hz while my subwoofer does low frequency effects, but the bottom end of 43Hz (I don't know the Fs for the woofer driver) will suffice until I dive deeper into building custom cabinets.

 

[GraysonPeddie]

Okay. I went ahead and order myself a Dayton BR-1 kit.

I bet the kit is the only way for novices who want to dive right into building their own speakers.

 

[adwilk]

Did you read the reviews..? I dont think bottom end extension will much of a worry.. most are quite surprised with the "bass". Good kit.... I think you'll like it.. Sounds pretty good... not super efficient but sounds pretty darn good...

 

[TLS Guy]

Okay. I went ahead and order myself a Dayton BR-1 kit.

I bet the kit is the only way for novices who want to dive right into building their own speakers.

That was a sensible decision. It will get you started and show the elements of speaker construction.

Now while you are getting used to that system and develop the itch for something better, start reading and really get to understand what is involved. Save your money and start honing your skills.

Good listening and Good luck.

 

[Swerd]

For GraysonPeddie and anyone else who may be in the same position, the Dayton BR-1 kit is a great way to get started in DIY speaker building. The instructions that come with that kit were written with the intention of teaching the novice who wants to learn. They are a great introduction to the subject. It not only gives detailed instructions for assembling the crossover board, it also explains what are the functions of the various circuits in the board. It includes illustrations that show a speaker's frequency response before and after adding various crossover circuits. After reading that you should understand why pre-made generic crossovers are almost never good to use.

Thanks to adwilik for offering that advice.

 

[TLS Guy]

For GraysonPeddie and anyone else who may be in the same position, the Dayton BR-1 kit is a great way to get started in DIY speaker building. The instructions that come with that kit were written with the intention of teaching the novice who wants to learn. They are a great introduction to the subject. It not only gives detailed instructions for assembling the crossover board, it also explains what are the functions of the various circuits in the board. It includes illustrations that show a speaker's frequency response before and after adding various crossover circuits. After reading that you should understand why pre-made generic crossovers are almost never good to use.

Thanks to adwilik for offering that advice.

Yes indeed! Thanks adwilik and Swerd. My hat is well and truly off to Dayton. I downloaded the instruction manual and I was impressed. It will be a very good starter speaker and a fantastic educational tool. Those Dayton kits should go well up the list of recommended products.

Really all speaker manufacturers should have well thought out kits in their range, just like KEF used to. Raymond Cooke always made sure KEF kits were a prominent part of their offerings. I doubt there is a better way of building customer base and loyalty. Try explaining that to the business suits! Dynaudio used to and now don't and I hold that against them.