Designing some speakers, need a little help. - Home Theater Forum and Systems - HomeTheaterShack.com

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post #1 of 16 Old 03-26-08, 08:33 AM
Nathbonn
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Designing some speakers, need a little help.

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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post #2 of 16 Old 03-26-08, 09:39 AM
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Re: Designing some speakers, need a little help.

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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post #3 of 16 Old 03-27-08, 01:39 PM
 
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Re: Designing some speakers, need a little help.

Quote:
Nathbonn wrote: View Post
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.

Quote:
Nathbonn wrote: View Post
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.

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Nathbonn wrote: View Post
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.

Quote:
Nathbonn wrote: View Post
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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post #4 of 16 Old 03-27-08, 05:25 PM
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Re: Designing some speakers, need a little help.

Quote:
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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post #5 of 16 Old 03-27-08, 05:34 PM
 
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Re: Designing some speakers, need a little help.

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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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post #6 of 16 Old 03-27-08, 08:11 PM
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Re: Designing some speakers, need a little help.

I guess that would explain why so many speaker companies use spikes.
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post #7 of 16 Old 03-27-08, 08:43 PM
 
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Re: Designing some speakers, need a little help.

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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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post #8 of 16 Old 03-27-08, 11:09 PM
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Re: Designing some speakers, need a little help.

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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post #9 of 16 Old 03-28-08, 01:40 AM
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Re: Designing some speakers, need a little help.

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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post #10 of 16 Old 03-28-08, 02:04 AM
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Re: Designing some speakers, need a little help.

Quote:
avaserfi wrote: View Post
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.

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