# Designing some speakers, need a little help.



## Guest (Mar 26, 2008)

Hello, I'm a product designer at Sheffield Hallam in the UK and have decided to design some speaker for one of my projects, to be honest I started this project thinking it would be pretty straight forward but i was badly mistaken.

Up to now the I've decided I'm going to design some floor standing speakers with the general 3 speaker system, high, mid and low speaker separation and will be using a nice looking solid wood and the Biwire system, but im struggling to make decisions on what type of material to use for the components.

So here are some of the questions I'm after to progress with this project, hopefully some light can be shed on these questions.

First of all tweeters. Amongst other materials I've seen aluminum and titanium tweeter, what is generally the best material for a set of main speakers for the home when it comes to sound quality? or is there some kind of future material coming on the scene which is not really known about yet?

Also there are all kinds of tweeter like AMT or ribbon tweeter and many more, generally what type is used for a loudspeaker and sufficient for general home use?

Domes, paper, plastic or kevlar? I have to admit I am going for the Kevler up to now as I just think it looks cool, but does this material have any benefit over paper or plastic or vice versa when it comes to sound quality? or again, is there any kind of wildcard material which is not really known about?

Speaker spikes, do these really have any kind of benefit on sound quality?

I have researched and researched and found out quite alot but to be honest I have been overwhelmed, there is just so much different stuff out there and so many pros and cons to anything I find relavent, thats why I've turned to forums now where the real audio heads are, to get real feedback and not a sales pitch.

Any reply to these questions will be greatly appreciated.

I will upload the designs I come up with as I progress.

Thank you.


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## drdoan (Aug 30, 2006)

Welcome Nathbonn. Glad you have you here. Your tweeter question is a great one. I think you should spend some time listening to different tweeters installed in commercial speakers at your local audio shops as much as possible. Hopefully, you will get a sense of how each type will present its sonic signature. Of course, you will never find the perfect tweeter, or woofer for that matter. Others will give better advise. Have fun, Dennis


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## avaserfi (Jul 5, 2007)

Nathbonn said:


> Hello, I'm a product designer at Sheffield Hallam in the UK and have decided to design some speaker for one of my projects, to be honest I started this project thinking it would be pretty straight forward but i was badly mistaken.


Welcome to the forum. I will try to address each question, but I should warn you simply slapping some drivers together with a crossover will not result in optimal sound quality. There is much research dedicated to loudspeaker design that is extremely beneficial to gain an understanding of.



Nathbonn said:


> Up to now the I've decided I'm going to design some floor standing speakers with the general 3 speaker system, high, mid and low speaker separation and will be using a nice looking solid wood and the Biwire system, but im struggling to make decisions on what type of material to use for the components.


Three way speakers are extremely typical, in fact, I am currently working on a design of relatively compact towers for myself. As far as working with solid wood goes, I wouldn't really recommend it. Solid wood has a tendency to warp due to humidity and temperature as well as other factors. Typically working with a high grade plywood is far superior as it can easily be veneered and is more resistant to effects of the environment. Also, I thought I would inform you that if you use a passive crossover system there will be no audible benefits from having bi-wiring capabilities, but some people think it looks cool and it isn't too much work. If you go active, it would be needed that you have multiple binding posts for each driver.



Nathbonn said:


> First of all tweeters. Amongst other materials I've seen aluminum and titanium tweeter, what is generally the best material for a set of main speakers for the home when it comes to sound quality? or is there some kind of future material coming on the scene which is not really known about yet?
> 
> Also there are all kinds of tweeter like AMT or ribbon tweeter and many more, generally what type is used for a loudspeaker and sufficient for general home use?
> 
> Domes, paper, plastic or kevlar? I have to admit I am going for the Kevler up to now as I just think it looks cool, but does this material have any benefit over paper or plastic or vice versa when it comes to sound quality? or again, is there any kind of wildcard material which is not really known about?


Driver material can have some important roles, but is not how you should base your drive choice. Firstly, if you are planning on using these speakers in a near field situation (3 meters or less) then you simply need to look for a drivers and tweeters that are linear, low distortion and have few/no break-up points (resonant nodes) within the pass band. If you are going for mid/far field listening then you will want drivers that also have smooth off-axis response that matches the magnitude of the on axis response as well. I should note there are other factors to look at as well, but these are just some examples.

Basically, what I am saying is don't look at driver composition, but the actual data on how it reacts at certain frequencies and SPLs.



Nathbonn said:


> Speaker spikes, do these really have any kind of benefit on sound quality?


Actually, speaker spikes couple a speaker to the floor which is not a good thing. Rather I would recommend using a decoupling system such as a high grade dense foam that would decouple the speaker from the floor thus reducing/eliminating resonance.

If you have any more questions or want clarification feel free to ask. Also, more information on what you want to do with these speakers as well as budget and expectations would be useful. BTW, I am moving this to the DIY speaker section as it will likely get more traffic there.


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## PT800 (Feb 19, 2008)

> Actually, speaker spikes couple a speaker to the floor which is not a good thing. Rather I would recommend using a decoupling system such as a high grade dense foam that would decouple the speaker from the floor thus reducing/eliminating resonance.


I would totally diagree with that statement. Using spikes will tighten the bass, most certainly with subs, and will provide more open and airy highs.
I know from where I speak, I added spikes to an old system, and they did just that.


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## avaserfi (Jul 5, 2007)

PT800 said:


> I would totally diagree with that statement. Using spikes will tighten the bass, most certainly with subs, and will provide more open and airy highs.
> I know from where I speak, I added spikes to an old system, and they did just that.


I must point out that anecdotal evidence is everything but evidence especially when polluted with bias. If you truly were interested in discovering the effects of spikes and their effect on loudspeakers you would do a true double blinded comparison rather than one that is so easily effected by bias as is a similar situation with cables. Let me explain further:

It is simple physics that spikes actually couple a speaker to the ground by creating a point of contact and thus energy transfer between both the ground and the cabinet. This will most certainly create a problem with resonance. On the other hand using the method I suggested there would be complete separation between the ground and the loudspeaker allowing for no/minimal transfer of energy.

This increased resonance would do anything but tighten up bass in an unbiased situation. Also, it is highly unlikely that the spikes had any effect on the treble of your system due to the nature of the wavelength at these 
frequencies.

My statements are not based on personal opinion, but the science and credible research relevant to the field of loudspeaker design, perception and their relation to enjoyment as shown in the AES and other credible publications.


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## PT800 (Feb 19, 2008)

I guess that would explain why so many speaker companies use spikes.


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## avaserfi (Jul 5, 2007)

PT800 said:


> I guess that would explain why so many speaker companies use spikes.


Applying simple laws of physics would make one realize why spikes would be detrimental to sound quality. Thusly, what a speaker company sells, and what is popular does not necessarily correlate with high quality, Bose is a perfect example of this. It should also be pointed out that just because it is commonly accepted does not mean it is the proper methodology to implement. 

It should be noted I am referring to highest possible fidelity.

Another note would refer to self proclaimed audiophiles who claim various snake oils create higher sound quality. This is all based solely on bias and has no basis in reality - spikes happen to fall into this category.

I no longer wish to derail this thread. If you wish to debate the 'merits' of spikes feel free to create a thread on the subject.


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## mayhem13 (Feb 2, 2008)

I believe both of you are right on the subject. While the spikes will create additional resonance due to coupling, many people find the bass extension gained pleasing especially in a smaller system lacking in low end extension. In the Pro audio industy we would typically suspend our full range systems to avoid system resonance around 800hz that would create excessive feedback at high Spl. the same effect could happen in home listening environments at various frequencies excited by room modes lending to 'pollution' of absolute fidelity.While not as significant as feedback, the resonances will color the output which may be desirable given the frequency response of the given system.Going with an active crossover system will easily make such issues moot at normal listening levels.


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## JCD (Apr 20, 2006)

I think avaserfi made some great points and agree pretty much with everything he stated. 

I'd suggest that if you're really serious about building a set of speakers, I HIGHLY recommend going with a proven DIY design. Designing a set of speakers from scratch and getting a good result is time/cost intensive -- especially as a complete beginner.

Also, lets move any further spike pro/con arguements to another thread as avaserfi suggested -- the OP shouldn't have to wade through these arguements here.

Thanks.

Oh and welcome to the Shack Natbonn!

JCD


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## WmAx (Jan 26, 2008)

avaserfi said:


> Firstly, if you are planning on using these speakers in a near field situation (3 meters or less) .


You consider 3 meters to be near field? I suppose the qualifications can get a bit tricky, depending on the specific conditions. I would consider 1.5 meters near field _in effect_. 3 meters distance in a normal size room would have to be considered at the end range of mid-field, or perhaps even far field, _in effect_, in a small room. I classify these range descriptions in accordance with direct sound vs. ambient room sound contribution to the total sound field. At 3 meters in a normal room, you are going to have at least as much room contribution as you do direct speaker contribution. 

-Chris


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## 1Michael (Nov 2, 2006)

Here are some good foolproof designs. http://www.htguide.com/forum/forumdisplay.php4?f=39
I dont like reinventing the wheel:bigsmile:


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## Guest (Mar 28, 2008)

Hi all, thank you all for your responses, its been very helpful.

When I started this project I thought I would be able to full understand all the working of a speaker and be able to design one that theoretically worked with beautiful sound quality in just two months lol, man was I being foolish there, I never understood how complex this area really is, I thought that there would be a universal standard of getting sound quality by basically using the the most expensive material ect.

After some time researching in to the technologies and science behind the workings of speakers I've now come to the conclusion that it will be best for me to take a more conceptual approach to this project and lightly touching on the componets, technology and materials used to simply justify my concept design as I simply do not have enough time to fully understand fine technological issues surrounding this area.

So up to now I'm going to make some floor standing speakers, the cabinets will be made of some kind of ply wood or MDF with a nice finish.

I wont be using the biwire set up as I have had quite a few responces to this saying that there is not really any need for it in my circumstance (a set of speakers for the general home) I will be avoiding right angles for my cabinet (I don't fully understand why this is seen as better) but supposedly it it so as a designer I will take this on board.

I will be using bass ports. Even though I know they have to be a the right size in conjunction with the cabinet and the drivers but thats not something I will be going into in too much depth with. The fact that they give better bass if used right is good enough for me. The mid and high ranged speakers still have to be air tight as bass ports only apply to base.

I will be using 3 speakers in each cabinet each doing their specific job, low=woofer mid speaker and a tweeter=high. For the tweeter I will be using a hard material such as aluminum or titanium as there are known more for there high frq and from the research I have done this seems in general what what a tweeter is all about.

I will be using Kevlar for the low and mid ranged speakers because I think it looks cool :bigsmile: and companies such as Bowser and Wilkins say that it has positive attributes for breaking sound up or something so thats good enough for me because I again...I think it looks cool also:bigsmile:

erm yeah, I know that this is all very very vague for people who know all about the technology behind the speakers but this is going to be a conceptual design.

As for the forum community I would like you to point out anything here that is totally wrong in some of the choices and information I feel I briefly understand and maybe suggest something else if it really does not make any sense. I have processed the information I have gained over the last week or so to the best of my ability but this has got to end, I could go on like this and be in this state of confusion for the rest of my life:dunno:

But please remember that this design is not going to be a fully resolved design but rather a design that follows some basic rules to justify a pair of loudspeakers for the general home.

Thank you.


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## JCD (Apr 20, 2006)

Just a few comments.. 


The various materials used to make drivers usually are good at somethings while having compromises in other areas. More often than not is the engineering behind the driver rather than just the materials themselves that define whether or not a particular driver sounds good or not.
I don't think there is anything wrong specifically with the choices you've made just that I think you might be reading too much into the marketing (e.g., B&W and Kevlar) departments (dis?)information.
Most speakers don't have indivdual compartments for the various drivers. That's not always true, but "usually".
I actually prefer soft dome tweeters to metal domes. Some prefer metals. Some prefer ribbons. Some prefer...
Since you're going with a 3 way design (which, again, is a LOT more difficult to get right vs a 2 way design) you may not need the bass ports to get the lower bass extension. I think, all things being equal, a sealed design is "tighter".
Right angles aren't that bad unless you're going to build a perfect square box. Almost all speakers are some sort of rectangular box as opposed to trapezoidal. And right angle boxes are a LOT easier to build.
Round edges on the baffle are a good thing.
Rather than highlighting the materials used to make the driver, you should key in on how the drivers mesh together.
And again, if you're looking for a final result that is guaranteed to sound good, consider a kit. If you're in this for the challenge/fun of it, then no problem.

JCD


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## Dryseals (Apr 5, 2008)

Hello Nathbonn, new guy here but I though it worth while to reply to your post. I've played with systems since I was ten, and now I'm fifty. So lets just say I've been able to gather some biased opinions for 40 years.
First and foremost, you'll find eveyone agrees and disagrees on what sounds the best. And through my many years of building, I've come to a few conclusions and have been able to do some off the cuff comparisions.
I get my hearing checked each year, part of my job working in industrial atmosphere. And so do the people I work with. From the graph of the hearing tests they perform everyone hears a tad different, and some dramatically different. So our hearing curves are not flat like the ones the speaker companies sell us. So what I may be able to hear is different than what you may be able to hear. It comes from genetics and what abuse your ears have taken over the years.

Then there is what you think you should be able to hear vs what you really do hear. This come from exposure and memory. So while we are both sitting at a live performance of say some acoustical guitars, I may hear certain sounds at different levels than what you may hear. When we play these sounds back over a sound system, the sound I heard at the concert will need to sound the way I perceived it vs the way you perceived it. What are we hearing? harmonics and reflections at different sound levels.
And then there is personal preference. We could have 20 females vocalist sing the same song at the same tempo et al and you'll like one more than I may like another. Which goes along with the looks of the speaker. If I think a speaker is ugly, no matter how great the sound really is, I may never like the sound it makes. While the same components in a more pleasing design will automatically sound better to me than the ugly speakers. Psychoacoustics?

So with all that said, will a measured response of a system be able to tell me what going to sound good? Maybe, but only my ears will tell me. So my advise to you is to go out and listen to several different manufacturers and see what types of speaker formats you enjoy the best and go from there.


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## DrGeoff (Dec 27, 2007)

PT800 said:


> I would totally diagree with that statement. Using spikes will tighten the bass, most certainly with subs, and will provide more open and airy highs.
> I know from where I speak, I added spikes to an old system, and they did just that.


I use steel ballbearings (about the size of marbles) unser the studio nearfield monitors. This works a treat for decoupling. You could also use glass marbles. I've also done this in makeshift monitoring rooms for live recording situations.

Spikes (or marbles) won't do anything for HF, they simply decouple the cabinet vibrations (particularly at resonance) from the surface that they sit on. If it's on a dense hardwood or concrete surface they probably won't make any difference at all.


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## DrGeoff (Dec 27, 2007)

avaserfi said:


> Three way speakers are extremely typical, in fact, I am currently working on a design of relatively compact towers for myself. As far as working with solid wood goes, I wouldn't really recommend it. Solid wood has a tendency to warp due to humidity and temperature as well as other factors. Typically working with a high grade plywood is far superior as it can easily be veneered and is more resistant to effects of the environment. Also, I thought I would inform you that if you use a passive crossover system there will be no audible benefits from having bi-wiring capabilities, but some people think it looks cool and it isn't too much work. If you go active, it would be needed that you have multiple binding posts for each driver.


Natural timber construction is a poor choice of material. The grain structure has different strengths and flexibilities in each direction and can cause unwanted cabinet resonances. High density non-grained material is best for cabinet construction. MDF is usually preferred, however ply is also commonly used.

There are audible benefits with active crossovers over passive designs, however this is largely dependent on the listenting situation. For example, a set of nearfield monitors in a studio are run at moderate levels all day and used for accuracy of detail. You want them to sound the same at the start of the day as at the end of the day, so most use bi-amped designs to achieve this. The crossover components have tolerances which are thermally dependent and, if moderate power is run through them over a long period, the component values will change, causing a change in what is heard. Active crossovers have tiny amounts of power run through them and will remain consistently in spec. However they are more expensive since you need more amplifiers, power supplies etc.

Even with an active crossover design you should include a capacitor in series with the tweeter if connected to a DC coupled amp. This limits the possibility of a click or thump destroying the tweeter. The cap should be sized so it is not contributing significantly to the filtering at the crossover frequency.


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