Hi guys
I would like to experiment with open baffle speakers on the cheap and was thinking of building one using the SB20FRPC30-8 which I have installed in my car and was really impressed by it.
The plan is to have the speakers eq'ed (if needed) to reach moderate levels below 80hz and then crossed them to by subs.
Would you be able to offer any guidance regarding driver selection, baffle size (if possible to be minimal and short) and expected bass response based on xmax? I don't know how to properly simulate this.
Thanks!
I would like to experiment with open baffle speakers on the cheap and was thinking of building one using the SB20FRPC30-8 which I have installed in my car and was really impressed by it.
The plan is to have the speakers eq'ed (if needed) to reach moderate levels below 80hz and then crossed them to by subs.
Would you be able to offer any guidance regarding driver selection, baffle size (if possible to be minimal and short) and expected bass response based on xmax? I don't know how to properly simulate this.
Thanks!
Oh thanks for that, didn't know there was a formula to determine the baffle. This is really helpful.
The formula's 95 db is anechoic at 1m? If so that would be 86db at 3m listening position. Adding a second speakers and room gain would probably go back to 95 db, so I guess that would be a good place to start.
I am not that technical so excuse my ignorance, how does the formula take into consideration the specifics of the speaker? Xmax is enough?
Spreadsheet here to help show some of this. It's typical to use Sd and Xmax to calculate theoretical output.
https://www.linkwitzlab.com/spl_max1.xls
Some drivers can play pretty cleanly well beyond Xmax, while others can't. Regardless, in standard driver data Xmax is still what's used most often to determine limits.
There's probably more theory/math than you want to take in at the next link, but the page goes through the basics also and offers some examples that might be useful to you.
https://www.linkwitzlab.com/models.htm
https://www.linkwitzlab.com/spl_max1.xls
Some drivers can play pretty cleanly well beyond Xmax, while others can't. Regardless, in standard driver data Xmax is still what's used most often to determine limits.
There's probably more theory/math than you want to take in at the next link, but the page goes through the basics also and offers some examples that might be useful to you.
https://www.linkwitzlab.com/models.htm
You're welcome!
I used Hornresp's OB wizard to sim it, so used your driver's specs with Xmax its one way max linear excursion. Install HR and use its 'Import' option to install/view it.
T/S Explained
T/S Equations and how each one affects the others
1 m in 2pi (half) space
95-(20log(3/1)) = 85.46 dB
If by 'adding' you mean stereo, then +3 dB
@styjp - SB Acoustic SB20FRPC30-8 hit my door this week. Honestly I didn't have much hopes as per Qts, Qms, Qes values, that, theoretically, disqualify it for open baffle. I placed it in piece of plywood 600mmx300mm as an baffle (so basically nothing) and to my big surprise it plays dam good. BUT, a big but - if you don't use DSP processor - forget about this speaker. See correction curve (set up by ear so far as I didn't have time to set up measurement rig yet). Without DSP you can't make it play. With DSP => my Lord! It really sing
@styjp - SB Acoustic SB20FRPC30-8 hit my door this week. Honestly I didn't have much hopes as per Qts, Qms, Qes values, that, theoretically, disqualify it for open baffle. I placed it in piece of plywood 600mmx300mm as an baffle (so basically nothing) and to my big surprise it plays dam good. BUT, a big but - if you don't use DSP processor - forget about this speaker. See correction curve (set up by ear so far as I didn't have time to set up measurement rig yet). Without DSP you can't make it play. With DSP => my Lord! It really sing
This is actually the size of baffle I wanted to experiment with. Do you use any subs or just the speakers? I guess you can pump up the bass with DSP but how loud can this get with such corrections?
Also what's your target curve with that dsp? A measurement would be nice!
Thanks!
@styjp - this is good question - how loud. Principally quite but it also heavily depends on music material. I listen mainly to classic where bass is not so densy. But if you play eg. Marcus Miller speaker is trying to jump out the chassis Another topic is bass quality - you can make wonder with DSP but if you go too far bass gets boomy. Generally - unless you are not more than 5W per channel you are good. So it's good combo to small tube SE amp (I have EL84 SE and it makes happy combo). Today I mounted it in larger enclosure with open back inspired by Klang+Tone (see Cheap Trick 269 project). I have Monacor sp 205 as well so will try today. If it's not gonna work nice for me I will give up with point source concept and back to my original well prooven construction with tweeter (actually it's Faital 3FE25 which I found to work amazingly as tweeter + Monacor sp205 in the mid + 2 x GRS 8" woofers all in two section open baffle)
Another topic is bass quality - you can make wonder with DSP but if you go too far bass gets boomy. Generally - unless you are not more than 5W per channel you are good. So it's good combo to small tube SE amp (I have EL84 SE and it makes happy combo). Today I mounted it in larger enclosure with open back inspired by Klang+Tone (see Cheap Trick 269 project). I have Monacor sp 205 as well so will try today. If it's not gonna work nice for me I will give up with point source concept and back to my original well prooven construction with tweeter (actually it's Faital 3FE25 which I found to work amazingly as tweeter + Monacor sp205 in the mid + 2 x GRS 8" woofers all in two section open baffle)