# Build Parameters.



## avaserfi (Jul 5, 2007)

It seems there are quite a few DIYers here. I was wondering what parameters do everyone takes into account when selecting drivers, designing a cabinet and/or crossover, room acoustics and why? Also, what is your typical goal when building speakers?

I am interested in different peoples 'philosophy' on this topic.


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## BoomieMCT (Dec 11, 2006)

Be prepared for a lot of answers!

To explain by example I'll use the center channel I'm working on now. For most builds I make a set of key performance parameters when I start. Sometimes it is something I want to experiment with or a specific driver I want to try out. For this build the most important thing was dialog clarity, horizontal dispersion (for a wide sweet spot) and good midbass (for action movies). I also knew these were going to be for home theater only, so there would always be a sub, so output below 80Hz wasn't of too much concern. 

Taking these constraints I decided a mini-tower with a thin baffle would work best. From experiments building speakers (especially recently helping Anthony with his center channel) I thought I'd try mating the BG Neo3PDR to some Dayton Reference speakers. Listening to Anthoy's tests made me appreciate the "metal cone" sound for HT use as well as the great horizontal dispersion of the NEO3PDR tweeter. While I like his dipole 3-ways a lot (and was tempted to rip off all his work) that design wouldn't work in my HT for placement reasons so I thought I'd try a front ported monopole using four smaller drivers (I went through a single-driver phase so this also influenced my decision). I figured the smaller drivers would have a higher cone breakup point and should make crossover design easier. Also my HT would need 8 ohm speakes, not 4 ohm like Anthony.

So I ordered the parts and build a test baffle. I hooked this up to an active crossover and did some measurements and listening tests to make sure they sounded good around the x-over point and sounded good in general. It was good I did this as my original concept for an x-over and driver layout (TMMMM 2-way) wasn't going to work. I ended up changing to a MTMWW 2.5 way design that I'm much happier with. While this testing was going on I built a simulation in Passive Crossover Designer and anthother in Unibox (both free FRD Consortium products). This led me to a basic passive crossover design which I then tested and refined in the test baffle using my box o' spare x-over parts.

My next step is to build the actual enclosure and do some final fine-tuning and in-room testing.


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## drf (Oct 22, 2006)

wow, they are some pretty in depth parameters. I design my speakers to sound as best as possible given whatever limitations I might have for that particular project.

For example power or budget might be a limiting factor or there might be no limiting factor except room accoustics.


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## avaserfi (Jul 5, 2007)

I was hoping for more replies, but now its time for the follow-up question. How did you determine your parameters? For example, what lead you to believe option X would sound better than option Y? 

It seems the question of what is answered for the most part, but not why. I am interested in both.


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## BoomieMCT (Dec 11, 2006)

avaserfi said:


> I was hoping for more replies, but now its time for the follow-up question. How did you determine your parameters? For example, what lead you to believe option X would sound better than option Y?
> 
> It seems the question of what is answered for the most part, but not why. I am interested in both.


Basic speaker design books explain what T-S parameters tend to work well in various enclosures so I won't repeat that here. Beyond that different people develop preferences for different sounds. Some people like metal tweeters, some soft dome, kevlar mides, blah, blah, etc and they tend to use similar drivers. Further beyond that you have to look at the FR of the drivers and note and breakup modes or other blips. Finally you just have to build a test baffle and listen. If you aren't building from a plan there is no substitute for actual listening and testing and no amount of computer simulation can replace that.


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## drf (Oct 22, 2006)

avaserfi said:


> I was hoping for more replies, but now its time for the follow-up question. How did you determine your parameters? For example, what lead you to believe option X would sound better than option Y?
> 
> It seems the question of what is answered for the most part, but not why. I am interested in both.


In order to explain why option A is better than option B you'd have to define what "sound better" actually means. Remembering that sound perception is both objective and subjective so everyone has a different definition of good sound. I personally like quite a wide range of tonal qualities (a result of working with many live artists) so I have an open mind about what works and what doesn't. I also like a challenge and thus enjoy trying to get the best sound out of the cheapest/most obscure drivers. I do read alot of threads where people spend hundreds of $$ on drivers and materials, build a speaker based on a well regarded design/alignment, place these speakers into a treated room then go on about how good they sound. Of course they sound good, what do some of these people expect? the sound of a pair of $20 AWA's :dizzy: 

I guess after having typed all that, I'd say there isn't necessarily a better option unless you fully complete two or more designs and carry out side by side comparrisons to see which one gets the results you expected. I also think that the design process can be overcomplicated too. The physics of sound does not change. You can look up many studies and physics books to find this out. So once we uinderstand the physics of sound the rest is elementary. 

My 2c


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## Dryseals (Apr 5, 2008)

drf said:


> In order to explain why option A is better than option B you'd have to define what "sound better" actually means. Remembering that sound perception is both objective and subjective so everyone has a different definition of good sound. I personally like quite a wide range of tonal qualities (a result of working with many live artists) so I have an open mind about what works and what doesn't. I also like a challenge and thus enjoy trying to get the best sound out of the cheapest/most obscure drivers. I do read alot of threads where people spend hundreds of $$ on drivers and materials, build a speaker based on a well regarded design/alignment, place these speakers into a treated room then go on about how good they sound. Of course they sound good, what do some of these people expect? the sound of a pair of $20 AWA's :dizzy:
> 
> I guess after having typed all that, I'd say there isn't necessarily a better option unless you fully complete two or more designs and carry out side by side comparrisons to see which one gets the results you expected. I also think that the design process can be overcomplicated too. The physics of sound does not change. You can look up many studies and physics books to find this out. So once we uinderstand the physics of sound the rest is elementary.
> 
> My 2c


I agree, and with my 2c we'll almost have a nickle.

I've been doing this for close to forty years and reproducing sound boils down to what you want to hear, what you think you should hear and what you really can hear. Not all people hear the same. Inside watching a movie, I like my speakers to blend into the room, to almost hide. I'm wanting to watch a movie, not a speaker.

Outside, in the shop, I don't mind seeing the speaker. Last night while cranking out some more cabinets and cranking on the tunes, I caught myself staring at the little Tang Bangs in amazement as to how good they could handle the lower ends and not get over stressed. I'll build a set of speakers and play with them in the shop for a long time before ever moving them into the house. The shop is a four car garage, dedicated as a shop. Concrete floor and wood cabinets with tools all around. If I can make them sound good in an uncontrolled enviroment, they'll sound good in a controlled enviroment.

I have Soundeasy and all the electronic test gear you could ever want, but I tend to use the testing for initial set up and then make changes on design for the way I want them to respond and I know I'm getting good results when I getting ready to switch on a saw and the sound of the singers voice is so clear, it makes me stop and just listen.


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