Why build speakers?

[WmAx]

Yes, of course... I hadn't thought about that. It's not dissimilar to creating harmonics on a guitar string I guess.

Yes. Similar. Though, do realize, when you install a brace, you also reduce the overall surface area of the new resonance(assuming it is assymetrical placement along the original resonance span area). With enough asymmetrical bracing, dividing the panels up into enough different resonances at far enough intervals, it is possible to substantially reduce the resonance(s) to a non-issue. But to successfully apply this would require extraordinary efforts in bracing, resulting in a system no less complex(perhaps more complex) to construct as compared to the heavy bracing + constrained layer method. Both will be extremely high in weight, compared to standard hi-fi speakers of the same relative size.

The first thing that came to my mind was to use accelerometers on a prototype box in order to measure vibration. Having read more on your replies, and the two articles by Mark Sanfilipo (thanks jaxvon) it sounds possible.

Yes, you can analyze the relative differences on an isolated section of panel in this manner.

Would it be worth playing different frequencies and measuring the accelerometer output at different points on a cabinet? My thinking is that you could add bracing in those areas with the largest movement. I accept you wouldn't be separating cabinet movement from speaker movement, or speaker movement from cabinet pressure.

Yes, is an effective(if time consuming) method of strategic application of bracing.

Surely a narrow, high amplitude resonance would be very audible, or is the point that it's moved to a frequency above human hearing? (or instead that having a single spike is better than numerous frequencies being affected?)

I know that it seems as if it would be very audible, but Floyd Toole demonstrated in his research(as cited in my last post) that the opposite was true. A high Q, high amplitude resonance is less audible than a lower Q, lower amplitude resonance, relatively speaking.

Is that why some speakers have drivers on a sloping baffle? It always struck me as a little odd, as my understanding was always that the best sound came from the center of a driver, and (within reason) you don't want to be listening to off axis sound (either direct or reflected).

Sloped baffles are typically used to align the acoustic centers of the mid range and treble drivers. This allows for superior optimization of the crossover. You can also use a staggered baffle, but you will then have additional diffraction issues to deal with.

I do have some ideas on making a relative low weight but low resonance cabinet system with normally available materials, and I intend to adapt this into a near future project(special high linearity guitar monitors). Please PM me for any specific details on construction or ideas of construction. This is exceeding the scope of this thread.

-Chris

 

[Buckle-meister]

This is exceeding the scope of this thread.

Threads that I start are not limited by scope.

 

[Hi-Fi ve]

There is a way for novice DIYers to achieve advance results right from the start. There are seasoned DIYers who have done the works and decide to share the knowledge. I simply copied what he did and learned tremendously.
Link

 

[sploo]

Yes, is an effective(if time consuming) method of strategic application of bracing.

OK. I'm not an electronics guy myself, but I work with a bunch of them, who have suggested a few ways of getting hold of some parts. Might be worth pursuing in the future.

I know that it seems as if it would be very audible, but Floyd Toole demonstrated in his research(as cited in my last post) that the opposite was true. A high Q, high amplitude resonance is less audible than a lower Q, lower amplitude resonance, relatively speaking.

Interesting. We have a few AES members where I work, so I'll see if I can get access to a copy.

I do have some ideas on making a relative low weight but low resonance cabinet system with normally available materials, and I intend to adapt this into a near future project(special high linearity guitar monitors). Please PM me for any specific details on construction or ideas of construction. This is exceeding the scope of this thread.

Will do. Thanks Chris.


EDIT: Hi-Fi ve, thanks for the speakerbuilder link. I've seen the site before, but it's well worth a visit for anyone that's interested in the field.

 

[WmAx]

EDIT: Hi-Fi ve, thanks for the speakerbuilder link. I've seen the site before, but it's well worth a visit for anyone that's interested in the field.

I have not checked out the speakerbuilder.net link in a long while, but unless it's changed radically since then, it is only unseful for basic information. Also, there is some small amount of snake oil(in regards to crossover components and similar things), or at least there used to be.

-Chris

 

[Hi-Fi ve]

Also, there is some small amount of snake oil(in regards to crossover components and similar things), or at least there used to be.

Unless it’s by Robert Harley, you can do it by the book if the links are doubtful.

http://www.powells.com/biblio?isbn=1882580176

Personally, I’d rather spend time listening to good speakers than to build them. The reason I took diy route is because I couldn’t afford the speakers I liked. My first speaker project was a kit (more of a quick assembly project) from Madisound. After a few hours of listening, I knew there is no way I would ever resort to store bought speakers. Kit speaker are perfect for those who are in the same situation as I am (rather spend time listening than building them). R&D is already done and you get a good speaker at once. No learning curve to deal with. Only tricky part is being able to audition one before getting them but you can get around it by talking to people for opinions.

 

[chasw98]

I can't remember the last time I posted here but it has been a while. All of you guys should go take a look at http://www.htguide.com/forum/forumdisplay.php4?f=39 which is the missions accomplished section. There you will see the successes people have had building their own speakers that equal commercial offerings costing much, much more. I have aso found some of the smartest crossover designers there. Dennis Murphy comes by occassionally and I even prototyped for him on a center channel I was building to go with the main speakers I built.

You talk about measurement capabilities. Most guys have some form of software/hardware method of measuring the finished product. A properly built and braced cabinet will not have resonance of a level that matters and will usually exceed what you can buy in the store.

Here is the response of my center:

Here is the 80 pound unit:

Here is the crossover:

I have also built all the rest of the speakers in my 7.1 system. They have been A/B'd with $5,000.00 Vandersteen speakers and sounded just as good by all present. I don't do it to save money, but that is a point to take into account. I have found I can build a better speaker than I can buy. Towards the end of this summer I will be building some Avalon Eidolon clones. The Eidolons retail for approx $20,000. At this point in the collabaritive design stage, I believe there will be about 5 of us building them. Parts alone will cost around $2,500.00 but I will end up with a pair of speakers I could never afford to buy. I have quite an investment in tools, have been in the audio industry for about 25 years, and just enjoy making something myself. I don't know a lot about designing crossovers but everyone tends to help each other. You should try it sometime.

Chuck