I'm making an "all purpose" 2-way cabinet of around 20 litres, a size large enough to accommodate an 8"mid-bass should I choose to use one.
Front and back will be removable, and the back panel could have added internal panels to lower the internal volume should that be necessary.
I'd like to make it a sealed box, but is 20 litres too big for most 6.5" mid-bass units? My Mission 761 speakers are 6.5", sealed box around 10 litres.
Since I have 2 pairs I was thinking of transplanting one pair of units into the new box, but it would be much bigger.
Are there 6.5" mid-bass units that work into 20 litres sealed? Or do 6.5" units typically need something more like 15 litres or less?
How to proceed here?
Front and back will be removable, and the back panel could have added internal panels to lower the internal volume should that be necessary.
I'd like to make it a sealed box, but is 20 litres too big for most 6.5" mid-bass units? My Mission 761 speakers are 6.5", sealed box around 10 litres.
Since I have 2 pairs I was thinking of transplanting one pair of units into the new box, but it would be much bigger.
Are there 6.5" mid-bass units that work into 20 litres sealed? Or do 6.5" units typically need something more like 15 litres or less?
How to proceed here?
Generally with a sealed enclosure the volume can be quite large without a problem. If you port it, then you need to be more careful.
18w8531 I think fits this description at Q=0.7, it's used in the Zaph ZRT with a recommended 20L closed.
Quick online calc -
Quick online calc -
No subwoofers please. I don't mind losing a few notes off the bottom of the bass guitar/double bass. I'm a bass player myself and my imagination can fill them in. As they say, the cobbler's children have no shoes. I like the quality of the bass in sealed enclosures, specially double bass.
Also bear in mind I'm in the UK for unit availability so no Dayton etc. Plus I need a crossover design since I have no measuring equipment. Thanks!
Also bear in mind I'm in the UK for unit availability so no Dayton etc. Plus I need a crossover design since I have no measuring equipment. Thanks!
@andyjevans here's a link to the Zaph ZRT - everything in there that you need to build it - box design / crossovers / drivers -
http://www.zaphaudio.com/ZRT.html
parts available from Falcon Acoustics / Willys Hifi / Hificollective / Wilmslow Audio all in UK.
http://www.zaphaudio.com/ZRT.html
parts available from Falcon Acoustics / Willys Hifi / Hificollective / Wilmslow Audio all in UK.
That ZRT is a nice design but not cheap. I'd like some more economic options as well.
One of my main questions is why sealed box volumes are typically 20 litres for a 8" speaker and around 15 litres for a 6.5" speaker. Is this for commercial reasons because it's easier to sell a smaller 2-way speaker that will fit on a stand? Or is it because beyond a certain volume the resistance of the air in the sealed box becomes insufficient for optimum performance?
Tenson above suggests that sealed box volumes are quite flexible. If you go larger you presumably get more bass but does that impact the quality of the mids or what? Can you guys explain this? And how the optimum volume of a sealed box relates to Vas?
https://audiojudgement.com/sealed-enclosure-closed-box/
Quote "Increasing the volume too much, will lead to denying the effect of the spring, and the enclosure is an infinite baffle. Actually, the term infinite baffle is in the real world just an oversized sealed box. Below Vas it's an acoustic suspension, above Vas it's infinite baffle. For a good transient response, the speaker needs to start and stop exactly when it needs to. The internal air “spring” that acts like a suspension, helps with achieving these good transients."
It's not clear to me how you decide how much "spring" you need. Is this subjective or is there a formula?
One of my main questions is why sealed box volumes are typically 20 litres for a 8" speaker and around 15 litres for a 6.5" speaker. Is this for commercial reasons because it's easier to sell a smaller 2-way speaker that will fit on a stand? Or is it because beyond a certain volume the resistance of the air in the sealed box becomes insufficient for optimum performance?
Tenson above suggests that sealed box volumes are quite flexible. If you go larger you presumably get more bass but does that impact the quality of the mids or what? Can you guys explain this? And how the optimum volume of a sealed box relates to Vas?
https://audiojudgement.com/sealed-enclosure-closed-box/
Quote "Increasing the volume too much, will lead to denying the effect of the spring, and the enclosure is an infinite baffle. Actually, the term infinite baffle is in the real world just an oversized sealed box. Below Vas it's an acoustic suspension, above Vas it's infinite baffle. For a good transient response, the speaker needs to start and stop exactly when it needs to. The internal air “spring” that acts like a suspension, helps with achieving these good transients."
It's not clear to me how you decide how much "spring" you need. Is this subjective or is there a formula?
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6.5" is a little short size for the bass and mid-bass at the same time and sealed, or you need a little room, sealed too, hoping a little room gain.
If staying 2 ways, I'd try to go 8" + 29 mm tweeter in a WG : consider Heissmann acoustic for instance (but not sealed iirc) : the loudspeakers on wall is a good idea here too on this site because it mimics infinite baffle and had boundaries/surface bass as well as mid-bass lift (although there is always peaks and null but especially in the low endbut at least the filter is optimised by the designer here for that purpose).
Basicly, sealed needs >= 0.4 Qts on the driver side, this increases according the dcr of the serie coil low pass filter.
online calculator like the mh-audio.com above can give you an idea of the volume box and the low end. You generally want to design the volume for maximum flat : Qtc 0.7 and from them reduce this Qtc (snappier and tigther but less boom) by adding internal damping (wool and/or open cell foam melanim based) which increase in theory up to 20% the volume of the box. If you make the back of the cabinet removable à la Harbeth you can tune the quantity of filling according to what you hear. Then play with the distanceeof the front wall.
Some 6.5" makes more bass than others like the ScanSpeak Revelator advised. I would prefer it against a SBAcoustic for a 2 ways.
If staying 2 ways, I'd try to go 8" + 29 mm tweeter in a WG : consider Heissmann acoustic for instance (but not sealed iirc) : the loudspeakers on wall is a good idea here too on this site because it mimics infinite baffle and had boundaries/surface bass as well as mid-bass lift (although there is always peaks and null but especially in the low endbut at least the filter is optimised by the designer here for that purpose).
Basicly, sealed needs >= 0.4 Qts on the driver side, this increases according the dcr of the serie coil low pass filter.
online calculator like the mh-audio.com above can give you an idea of the volume box and the low end. You generally want to design the volume for maximum flat : Qtc 0.7 and from them reduce this Qtc (snappier and tigther but less boom) by adding internal damping (wool and/or open cell foam melanim based) which increase in theory up to 20% the volume of the box. If you make the back of the cabinet removable à la Harbeth you can tune the quantity of filling according to what you hear. Then play with the distanceeof the front wall.
Some 6.5" makes more bass than others like the ScanSpeak Revelator advised. I would prefer it against a SBAcoustic for a 2 ways.
My room size is 4.5 x 3.5 metres or 14’9” by 11’6”. Speakers fire into 4.5 meters. No wall behind the speakers - it's a large French window. I don't listen loud and use a 2a3 SE amp. So fairly warm bass and some room enhancement of bass. I like tone in the bass, particularly with a double bass. I listen to a lot of jazz, since I was a pro jazz musician. I like a realistic tone in the bass, not "slam" or tight bass, something more natural. A double bass doesn't have "slam", though it does have impact if it's amplified. It does have a rich tone, both plucked and bowed.
<<You generally want to design the volume for maximum flat : Qtc 0.7 >>
How do you calculate this with the T&S parameters of the mid-bass unit? You're speaking here of the Q of the box, yes?
I found this which I'll try: http://www.mh-audio.nl/Calculators/CBCQ.html
With the above, the SB 17MFC has an ideal sealed box of 14.7 litres, which looks pretty typical.
SEAS CA18RLY has an ideal sealed box of 25 litres
<<You generally want to design the volume for maximum flat : Qtc 0.7 >>
How do you calculate this with the T&S parameters of the mid-bass unit? You're speaking here of the Q of the box, yes?
I found this which I'll try: http://www.mh-audio.nl/Calculators/CBCQ.html
With the above, the SB 17MFC has an ideal sealed box of 14.7 litres, which looks pretty typical.
SEAS CA18RLY has an ideal sealed box of 25 litres
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Dayton audio drivers are available from Amazon UK (I've bought a few pairs of 3 1/2 inch drivers from them) including the DC 160 6 1/2 inch classic, currently £38.99p
If you like bass from a sealed box, you might prefer aperiodic vented enclosures.
If you like bass from a sealed box, you might prefer aperiodic vented enclosures.
I understand as I listen a lot of jazz, my main is an aperiodic sealed load and I tunned the filter for that blend of decay, articulation and tones in the bass.
Yep that is that mh-audio site I talked about, look at this first and be ready to read drivers datasheets : http://www.mh-audio.nl/Loudspeakers.html#top you find here what is needed to know the volume box and Qtc according the T&S drivers datasheets.
you can't go wrong as well with these ones : https://heissmann-acoustics.de/en/ and http://www.audioexcite.com/?page_id=985
Yep that is that mh-audio site I talked about, look at this first and be ready to read drivers datasheets : http://www.mh-audio.nl/Loudspeakers.html#top you find here what is needed to know the volume box and Qtc according the T&S drivers datasheets.
you can't go wrong as well with these ones : https://heissmann-acoustics.de/en/ and http://www.audioexcite.com/?page_id=985
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The Silver Flute 6.5 and 8 are both great inexpensive drivers that sound very good overall, plus easy to crossover with gentle upper breakup range. They work well in a sealed or ported box. The 6.5 wouldn't "drown" in 20 liters, neither would the 8 "choke" in it. Part numbers are W20RC38-04/08 W20RC38-04/08, costing $35 to $45 from Madisound.
@profiguy, he is UK based, not sure Silver Flute is easily avialable there ?
Consider the easy to source brands there as Fane, etc.
There are still some Peereless gemes : https://www.soundimports.eu/en/peer...MI_-jdy--vggMV0otoCR1iUAQqEAAYASACEgLWj_D_BwE
Consider the easy to source brands there as Fane, etc.
There are still some Peereless gemes : https://www.soundimports.eu/en/peer...MI_-jdy--vggMV0otoCR1iUAQqEAAYASACEgLWj_D_BwE
That was the first rec. mentioned in this old thread. https://www.diyaudio.com/community/threads/6-5-to-7-midwoofer-for-sealed-enclosure.195444/
And the Seas CA18RLY is still available.
jeff
Thanks for the aperiodic vent idea - I'm studying that.
The mh-audio calculator is pulling up some unexpected results.......
Scanspeak 18W-8546 - Fs 22Hz, Qts=.19, EBP=100, Qtc = 6.5 litres
Monacor SPH165 - Fs 33, Qts=.21, EBP=143, Qtc = 3.5 litres
Looks like a Qts of .4 or above is needed. But the SEAS U18 with a Qts of .37 has a Qtc of 8.3 litres. Hmmmmm....
The mh-audio calculator is pulling up some unexpected results.......
Scanspeak 18W-8546 - Fs 22Hz, Qts=.19, EBP=100, Qtc = 6.5 litres
Monacor SPH165 - Fs 33, Qts=.21, EBP=143, Qtc = 3.5 litres
Looks like a Qts of .4 or above is needed. But the SEAS U18 with a Qts of .37 has a Qtc of 8.3 litres. Hmmmmm....
Take a look at this one, factory built for a sealed cabinet and affordable.
https://www.diyaudio.com/community/...sealed-simple-loudspeaker-build-plans.352046/
https://www.diyaudio.com/community/...sealed-simple-loudspeaker-build-plans.352046/
There are Revelators for sealed too with the needed T&S.
Try to look also free designs from troels Gravesen in the Seas pages of his site.
Aperiodic vent idea is a bad idea for a beginner, do copy a ready made design imo.
liters are for Vb (volume box) , Qtc is the shape of the low pass magnitude of the driver in box ; 0.707 ; 1.00 ; 0.61 ; etc ; > 0.707 is towards more bass envelopment and < 0.707 is towards tigther sound . But also depends on the amp, source, room. Try not to choose 4 ohms speaker and too much low sensivity with your 3 W SE amp.
Try to look also free designs from troels Gravesen in the Seas pages of his site.
Aperiodic vent idea is a bad idea for a beginner, do copy a ready made design imo.
liters are for Vb (volume box) , Qtc is the shape of the low pass magnitude of the driver in box ; 0.707 ; 1.00 ; 0.61 ; etc ; > 0.707 is towards more bass envelopment and < 0.707 is towards tigther sound . But also depends on the amp, source, room. Try not to choose 4 ohms speaker and too much low sensivity with your 3 W SE amp.
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A spring doesn't stop any motion! It saves energy and gives it back!
With a smaller volume the Q of the driver rises - so less precision in theory.
In real life it's a little more complicated. Air spring is very linear compared to a speaker suspension so it can have good influence but it would need to dominate for significant influence and todays speaker are not built that way.
So - a too big closed volume is not really a thing, you just have a pretty gentle fall off of your driver.
And btw - 2 6,5" in closed volume don't give a lot of SPL. If you won't be on a budget I would recommend Purify to get the most possible SPL out of this size. I use 2 20cm per side in a relatively small room and they have to work hard sometimes ...
Yeah, most of today's drivers are so stiff it's effective motor strength (Qts') dominates.
(Qts'): (Qts) + any added series resistance (Rs)
(Qts'): (Qts) + any added series resistance (Rs)