Hi,
The Dayton driver will need a larger box than the drivers I mention.
around 20L sealed actually - it doesn't suit reflex loading well.
Its not going to be able to handle a lot of power - really depends
on if Xmax is specified as one way (6mm = 12mm bothway) or
bothway (6mm = 3mm oneway), the difference is 6dB of power
input.
The MCM unit is 8mm oneway, 16mm both, the TB's 12mm/24mm!
Quick analysis indicates reflex loading (or ABR) ~ 9L to 12L.
regarding #1 : 50$ on the amp and 20$ on the driver is skimping.
Given the time you'll spend making the box and finishing it
pushing the boat out a little bit on the driver makes sense.
Its the difference between an average and excellent sub.
Note that max volume in the low bass = cone area x excursion,
max volume in the upper bass = sensitivity x amplifier power.
For your purposes you need a low sensitivity driver, this means
for the bass extension the sub will be small. Low sensitivity and
high excursion also means it can sink the sub amplifier power.
A higher sensitivity unit needs a larger box and less
amplifier power for the same performance as the above.
🙂/sreten.
The Dayton driver will need a larger box than the drivers I mention.
around 20L sealed actually - it doesn't suit reflex loading well.
Its not going to be able to handle a lot of power - really depends
on if Xmax is specified as one way (6mm = 12mm bothway) or
bothway (6mm = 3mm oneway), the difference is 6dB of power
input.
The MCM unit is 8mm oneway, 16mm both, the TB's 12mm/24mm!
Quick analysis indicates reflex loading (or ABR) ~ 9L to 12L.
regarding #1 : 50$ on the amp and 20$ on the driver is skimping.
Given the time you'll spend making the box and finishing it
pushing the boat out a little bit on the driver makes sense.
Its the difference between an average and excellent sub.
Note that max volume in the low bass = cone area x excursion,
max volume in the upper bass = sensitivity x amplifier power.
For your purposes you need a low sensitivity driver, this means
for the bass extension the sub will be small. Low sensitivity and
high excursion also means it can sink the sub amplifier power.
A higher sensitivity unit needs a larger box and less
amplifier power for the same performance as the above.
🙂/sreten.
Huh, crazy, never knew that 🙂
Ok, I ordered the 150w amp and 8" sub from MCM.
I am heading to Las Vegas for the weekend, when I get back I will figure out if I am afraid of passive subs, or just want to use a port. 🙂
Thanks man,
Silly.
Hi,
meaured (courtesy of Zaph) vs claimed parameters :
Fs=30.95 hz 26
Qms=12.2863 14
Qes=0.2365 0.22
Qts=0.2320 0.22
Vas=23.88 l 30.5
SPL=86.59 1w/1m 87
Re=3.4 3.4
Le=2.42 2.47
BL=13.15 13
Xmax=16mm P-P 16
Using measured parameters I get the following (good shape for room gain):
10L with 32Hz vent tuning looks ideal to me.
(P.S. don't worry about the 2dB down at 100Hz, only affects efficiency)
🙂/sreten.
meaured (courtesy of Zaph) vs claimed parameters :
Fs=30.95 hz 26
Qms=12.2863 14
Qes=0.2365 0.22
Qts=0.2320 0.22
Vas=23.88 l 30.5
SPL=86.59 1w/1m 87
Re=3.4 3.4
Le=2.42 2.47
BL=13.15 13
Xmax=16mm P-P 16
Using measured parameters I get the following (good shape for room gain):
10L with 32Hz vent tuning looks ideal to me.
(P.S. don't worry about the 2dB down at 100Hz, only affects efficiency)
🙂/sreten.
Attachments
I'm back from Vegas, did you miss me? Made $150, should have ordered a better drive ;-)
Wow, 10L... that is a mere .35 cubic feet to us silly american's, which is like 8.5" cube (completely ignoring space for driver/port volumes). Crazy small! The wife is bound to approve 🙂
I didn't find this driver mentioned on Zaph's sight, got a link?
So, for a ported box, unless I screwed up in WinISD, it says I can use a 1 1/8" port, at ~6.5" long (ie, the whole tube w/ modification from parts express).
WinISD shows "rear port velocity" as peaking at 32 ft/s, which from what I can tell is "ok".
Anybody want to confirm that I am not still hung over from Vegas? 🙂
Wow, 10L... that is a mere .35 cubic feet to us silly american's, which is like 8.5" cube (completely ignoring space for driver/port volumes). Crazy small! The wife is bound to approve 🙂
I didn't find this driver mentioned on Zaph's sight, got a link?
So, for a ported box, unless I screwed up in WinISD, it says I can use a 1 1/8" port, at ~6.5" long (ie, the whole tube w/ modification from parts express).
WinISD shows "rear port velocity" as peaking at 32 ft/s, which from what I can tell is "ok".
Anybody want to confirm that I am not still hung over from Vegas? 🙂
http://www.users.bigpond.com/bcolliso/index.htm
All you want to know about vented subs and flared ports but never asked.
including a calculator :
http://www.users.bigpond.com/bcolliso/flare-testing.htm#flare-it
Zaph posted the measurements in this forum.
I'm highly dubious that that port would support maximum levels.
🙂/sreten.
All you want to know about vented subs and flared ports but never asked.
including a calculator :
http://www.users.bigpond.com/bcolliso/flare-testing.htm#flare-it
Zaph posted the measurements in this forum.
I'm highly dubious that that port would support maximum levels.
🙂/sreten.
Hi,
if the complications of accurate port tuning and sizing in small boxes
seems to be too complicated then I suggest the passive radiator.
(winISDPro gives 40L as the Vas of the passive radiator)
Following are my quick sims of the response, which you
should independently verify. 9/10L looks good to me.
Would be best to get someone to verify in another simulator, e.g. Unibox.
🙂/sreten.
if the complications of accurate port tuning and sizing in small boxes
seems to be too complicated then I suggest the passive radiator.
(winISDPro gives 40L as the Vas of the passive radiator)
Following are my quick sims of the response, which you
should independently verify. 9/10L looks good to me.
Would be best to get someone to verify in another simulator, e.g. Unibox.
🙂/sreten.
Attachments
Hi,
32ft/s = ~ 10m/s.
in WinISD Pro 10L box tuned to 38Hz, 34mm O by 160mm long port :
for 150W I get max port velocity = 96m/s (320ft/s) at 34Hz.
To peak at 11m/s you need a port 10cm in diameter and 1.5m long.
🙂/sreten.
32ft/s = ~ 10m/s.
in WinISD Pro 10L box tuned to 38Hz, 34mm O by 160mm long port :
for 150W I get max port velocity = 96m/s (320ft/s) at 34Hz.
To peak at 11m/s you need a port 10cm in diameter and 1.5m long.
🙂/sreten.
Okay, so my problem was not looking at wattage I guess 🙂 Must have left it at default which was probably 1w.
So, clearly, this is going to be problematic. Given that larger diameter port also requires a longer one... I suspect the port isn't going to fit in my enclosure, which sounds problematic ;-)
I will have to play with it when I get home, since I don't have WinISD here... but seems like I may be *forced* to do passive radiator?
So, clearly, this is going to be problematic. Given that larger diameter port also requires a longer one... I suspect the port isn't going to fit in my enclosure, which sounds problematic ;-)
I will have to play with it when I get home, since I don't have WinISD here... but seems like I may be *forced* to do passive radiator?
Continuing this thread at http://www.diyaudio.com/forums/showthread.php?s=&threadid=80138 to get a better subject for the thread. This no longer has *anything* to do with a cheapy passive sub 🙂
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