Hi folks,
I'm new here and opened this thread because couldn't find directions for what I'm looking for.
I want to build a bluetooth boombox-style speaker with two 4" drivers and two 4" PRs.
I went for PRs after modeling for ported speakers with my drivers' specs in winISD, the results with ported was an enormous necessary internal volume for anything under 60-70 Hz.
The thing is I only have access and money for chinese PRs (like these https://aliexpress.com/item/4000203225569.html) but they have no T/S data or any specs for modeling.
Is there some empirical way I can test/measure resonant frequency for tuning it, like a variable sized box or something, and how could I do measurements with it?
I have no pro equipment for measuring.
Any insights would be much appreciated.
I'm new here and opened this thread because couldn't find directions for what I'm looking for.
I want to build a bluetooth boombox-style speaker with two 4" drivers and two 4" PRs.
I went for PRs after modeling for ported speakers with my drivers' specs in winISD, the results with ported was an enormous necessary internal volume for anything under 60-70 Hz.
The thing is I only have access and money for chinese PRs (like these https://aliexpress.com/item/4000203225569.html) but they have no T/S data or any specs for modeling.
Is there some empirical way I can test/measure resonant frequency for tuning it, like a variable sized box or something, and how could I do measurements with it?
I have no pro equipment for measuring.
Any insights would be much appreciated.
Theres a bit of a science re the whole PR thing. I once had a butchered pair of celestion ditton 44 mk2. They originally had a 8" woofer working a 8" PR. someone cut the hole bigger to fit a 10" driver working a 10" PR. Then won't on to box them in inside the cabinet. It didn't work. Horrible sound. So...dunno
You can't fool mother nature. You need a big paddle to make big (bass) waves in air. For a four-inch, 70Hz is about where you can get to with reasonable efficiency and output.
Right, that makes sense. So I may not try much below 70 hz when tunning.
70 hz still gives me a huge volume for ported tho... I think I might build a variable volume box for those PRs, with one "loose" side (not fixed) so I can push it in/out and make the box smaller or larger, as I'm unable to run the PRs in winISD given it's unkown specs.
I just don't know what to look for when doing this experiment besides listening and trying to figure out a good sounding bass. Should I try to measure and look for a peak at 70hz?
Huge for a 70Hz (16 foot) wave? Or just huge for a Four-Inch? Or just bigger than you would like?
Back in the dawn, they learned that a six-inch in a console would do 150cps OK (that whole parlor-radio fad) and 'full range" (to maybe 50cps) wanted Fifteens on large baffles or huge boxes.
Electrical Watts are far cheaper now, but that does not cure the problems of a too-small paddle making too-large waves. Neo-rubber will go further than leather surrounds but if you have to drive your cone a foot each way the air itself distorts (multi-tone intermodulation; Klipch wrote the first-dart paper).
Some new factory rigs seem to do better. I have a $40 stereo speaker (it was sold as "Bluetooth" but that has nothng to do with how it speaks) which blows-away any micro-speaker I have known. I think they use DSP to shake the cone where it does most good, and suppress all else. So in a heavy bass passage it may just drop-out the lowest notes to avoid mudding-up. That kind of technology is beyond my aged mind.
Huge for a portable boombox-style speaker, so yeah, just bigger than I would like.
Ok, I got that part... I don't want my 4" speakers sounding like a 15" subwoofer, as I understand it is impossible.
I'm a beginner in speaker design (not in music, physics and engineering, though) so the frequencies or ideas from the first post may be misleading. The PR path and those numbers were chosen based on my recent findings and scarce knowledge.
Anyways, what I aim for is a good sounding bass within the limitations of this equipment, to design the box and improve the bass region the best I can... So tips in that direction would be great, even if it diverges from original post ideas. Unfortunately bigger speakers and 30 liters+ box designs won't suit the project.