There's no single optimal volume for a driver. Within a certain range of volumes, a final choice should depend on one's design goal and limitation. It is true that the ER18RNX can be used in a smaller cabinet than the RS180. But you can use it in up to 20 to 21 liters to obtain deeper bass at the cost of power handling. See the predicted bass responses in two different cabinets in my MTM design page. You'll get the idea.
Again, it depends on your use of the speakers. I'd use a 20 liter box if I wanted to hear deep bass at a moderate volume level. I'd choose a 14 liter cab if I wanted to turn up the volume occasionally. A 16 to 17 liter box may be a good compromise. If you're going to use the speakers with a subwoofer with an AV receiver's high pass filter, a box volume won't matter.
The Seas woofer is known to have a well designed motor and suspension system. It should be able to handle a lot of power without being physically damaged even when it gets beyond its excursion limit to some degree.
The Seas woofer is known to have a well designed motor and suspension system. It should be able to handle a lot of power without being physically damaged even when it gets beyond its excursion limit to some degree.
Hi,
with 7W per channel you can forget about bass power handling concerns and
design for best extension and the output impedance concerns of your amplifier.
http://www.mhsoft.nl/spk_calc.asp#newqts
Just use amplifier impedance instead of inductor DCR, new Qts = 0.5.
23 to 27 litres tuned to 33Hz per driver seems workable, some mild peaking.
/sreten.
with 7W per channel you can forget about bass power handling concerns and
design for best extension and the output impedance concerns of your amplifier.
http://www.mhsoft.nl/spk_calc.asp#newqts
Just use amplifier impedance instead of inductor DCR, new Qts = 0.5.
23 to 27 litres tuned to 33Hz per driver seems workable, some mild peaking.
/sreten.Jay_WJ said:
sreten, perhaps you thought of the original poster. Peter is a different person.
Hi,
Indeed I did.
IMO box size and tuning does not affect power handling much, you
just get different types of maximum levels at certain frequencies and
overload at lower frequencies. For the ER18 power handling for any
sensible damped (room corrected somewhat) alignment with a box
17 +/-3 litres in practise will not vary much.
/sreten.sreten said:Hi,
with 7W per channel you can forget about bass power handling concerns and
design for best extension and the output impedance concerns of your amplifier.
Just use amplifier impedance instead of inductor DCR, new Qts = 0.5.
23 to 27 litres tuned to 33Hz per driver seems workable, some mild peaking.
Hi,
I'm the original poster
I did pretty much what you suggested .... I used Zout to calculate the Q with my amp - about 0.46 if I remember, so your 0.5 is close, well done.
With about 40 litres, the box simulations did show some peaking; but this could be minimised by a low port tuning. 32 Hz reduces the peak to about 0.7 dB IIRC, little seems to be gained by going lower; and 32 Hz gives a reasonable size port. Again, your suggestion is spot on. This tuning seems to give, on paper, a reasonable lf performance with a fairly gentle roll off, and reasonable group delay. Seems OK on balance, could be a lot worse!
Anyway, the boxes are nearly made; more news in a few days.
Regards
Mike
sreten said:
For the ER18 power handling for any sensible damped (room corrected somewhat) alignment with a box 17 +/-3 litres in practise will not vary much.
What do you mean by sensible damped & room corrected?
noob question!So any volume between 14 and 20 L will be more or less the same? what if I pair it up with a 100W Yamaha amp?
Peter
He talked about box damping. He meant unless you use the driver in an infinite baffle (i.e., free air) or in a very small closed box, you will not have much difference in power handling for real-world music application. So between 14 and 20 liters, power handling is not much of an issue. So, choose a volume that gives better bass response for you within that range. That's what sreten means.
Jay_WJ said:
LOL, how do I define a better bass response for me.... Guys, I'm lost here. I think this project is going to damage my eyes and be the reason for my getting my first pair of glasses ever!
I've been playing with WinISD and I have no idea what I am doing. One curve or another? They all look pretty to me
Also noticed I can change a parameter in WinISD "Ql" and I have no idea what it does. The help section says to leave at 7 but doesn't explain what it is....peter_m said:
In most cases, "better bass" should mean deeper bass, that is, more extended bass without response peaking. In a vented design (espeically commercial), it is common that a designer can't use a woofer's max potential in its extended bass reproduction due to box size limitation. If you're not going to use a subwoofer for music listening, a 20 liter box, as I suggested in my web page, will be better because it enables you to tune low for deeper bass without a response peak.
I've been playing with WinISD and I have no idea what I am doing. One curve or another? They all look pretty to me
Ql is a correction factor for box damping Q due to leakage loss. High value means little loss and low value, great loss. I think 7 is on a very low side.
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