richwalters said:
What do mean not suited for rock music?A Qt of 0.707 is regarded as the optimum compromise between boomy bass vs controlled bass response.
A Qt of 1 or higher will get really tiresome fast because all the bass will sound like someone beating a wet blanket with stick. I really advice against designing a box with a higher Qt than 1.
Hi there.......nearly all ready-made off the shelf loudspeakers have a Q's above 1 or some as high as 2 for cheaper models. They sound good and bass wacky, so the younger & middle age group buys'em up .....basic marketing philosphy.
You aren't quite right about the Q business.........I've floor standing units using 2 x 10" peerlesss 80140 in 3.88Cuft .. 110 Lit reflex with port in box base........the bass is full, powerful but not boomy with a Q of 1.2. You can have a high Q around that figure but that doesn't imply boom. MY cabinet design is an octet i.e 8 sided cabinet which has alot of internal bracing........this is the key to avoid internal resonances and odd nodes that colour the sound....the business of deoxidised copper cable to improve the sound.....is a load of expensive rubbish.
My other comment is that port sizes on many cabinets using large loudspeakers is often way too small.........using a too small port will create unwanted windage noises. The same goes for bracing.....not enough of it. A key for port sizes:
15" LS use 5" or 6" tubes
12" LS use 4"
10" LS use 3"
A speaker that has too low sys Q will require more amp bass boost headroom to compensate the tail off response, thus if the unit sensitivity is low i.e Spl 85dB, one risks burning out the coil from a high powered amp. I've seen it done so many times.
Designing cabinets for reflex may seem easy, but the trick is to get a proper physics fit of loudspeaker and it's home (the box).
You won't get far using studio monitors out here with a system Q of 0.7, it simply ain't got punch...I could never sell'em...the alignment is smooth but way too flat.
The aim is that the bass should be felt and heard, just as the carnival drum or the deep bass from a steel reggae band. If youv'e heard the steel group Tabu Tombo, you will soon appreciate that a bit of Q does no harm.
Perhaps we have a different judgment of Q's.....rock musicians and easy listening artists like to hear prominent bass i.e 1 or slightly above.
The nicest symphony keep Q around the 0.7
Wildest disco and outdoors a Q of 1 or 2 upwards. If we could design a loudspeaker which would fulfill all then I am happy with mine at Q=1.2.
VIVA reflex!
rich
You aren't quite right about the Q business.........I've floor standing units using 2 x 10" peerlesss 80140 in 3.88Cuft .. 110 Lit reflex with port in box base........the bass is full, powerful but not boomy with a Q of 1.2. You can have a high Q around that figure but that doesn't imply boom. MY cabinet design is an octet i.e 8 sided cabinet which has alot of internal bracing........this is the key to avoid internal resonances and odd nodes that colour the sound....the business of deoxidised copper cable to improve the sound.....is a load of expensive rubbish.
My other comment is that port sizes on many cabinets using large loudspeakers is often way too small.........using a too small port will create unwanted windage noises. The same goes for bracing.....not enough of it. A key for port sizes:
15" LS use 5" or 6" tubes
12" LS use 4"
10" LS use 3"
A speaker that has too low sys Q will require more amp bass boost headroom to compensate the tail off response, thus if the unit sensitivity is low i.e Spl 85dB, one risks burning out the coil from a high powered amp. I've seen it done so many times.
Designing cabinets for reflex may seem easy, but the trick is to get a proper physics fit of loudspeaker and it's home (the box).
You won't get far using studio monitors out here with a system Q of 0.7, it simply ain't got punch...I could never sell'em...the alignment is smooth but way too flat.
The aim is that the bass should be felt and heard, just as the carnival drum or the deep bass from a steel reggae band. If youv'e heard the steel group Tabu Tombo, you will soon appreciate that a bit of Q does no harm.
Perhaps we have a different judgment of Q's.....rock musicians and easy listening artists like to hear prominent bass i.e 1 or slightly above.
The nicest symphony keep Q around the 0.7
Wildest disco and outdoors a Q of 1 or 2 upwards. If we could design a loudspeaker which would fulfill all then I am happy with mine at Q=1.2.
VIVA reflex!
rich
That is incorrect. Assuming you are using EQ (bass boost), what really matters is the sensitivity at the lowest frequency you want to play, not the relative shape of the curve. A lower Q box will require less power below Fb.
Here's an example using a Shiva subwoofer driver in Q = .5 (green), .7 (yellow), and 1.2 (cyan) sealed boxes. Note the relative sensitivity. The 1.2 box is 13dB less sensitive than the .5 box at 20 Hz and will require 20 times the power rating for the same 20 Hz SPL.
An externally hosted image should be here but it was not working when we last tested it.
Hi there.....yes youre' right...I should have mentioned about tuning the port at a lower frequency than B4 alignment suggests. Too many late nights.
On my 4th order reflex cab's I deliberately aim for syst Q of 1.2 and tune port slightly below fb (35Hz)......to keep LF response curve up. This technique is done quite alot.
(I can't plot this here) as I have only Thiele/Small in snail Qbasic.
I would be grateful if you could put this detail into your super program as see how this reflex turns out:
Note 2 bass units used in cabinet below:
Each chassis unit Qt = 0.35;Vas=4.8Cuft (135lit); fz=25Hz
Box vol =3.88Cuft (110lit) port tuning 32Hz;
The real drawback of the reflex is the fourth order roll-off (24dB per oct) below fb res which requires the amp LF response to snap off sharply below this freq.
rich
On my 4th order reflex cab's I deliberately aim for syst Q of 1.2 and tune port slightly below fb (35Hz)......to keep LF response curve up. This technique is done quite alot.
(I can't plot this here) as I have only Thiele/Small in snail Qbasic.
I would be grateful if you could put this detail into your super program as see how this reflex turns out:
Note 2 bass units used in cabinet below:
Each chassis unit Qt = 0.35;Vas=4.8Cuft (135lit); fz=25Hz
Box vol =3.88Cuft (110lit) port tuning 32Hz;
The real drawback of the reflex is the fourth order roll-off (24dB per oct) below fb res which requires the amp LF response to snap off sharply below this freq.
rich
Rich, I'm using WinISD Pro (alpha version.) It's a free download.
http://www.linearteam.dk/default.aspx?pageid=winisdpro
http://www.linearteam.dk/default.aspx?pageid=winisdpro
richwalters said:
Hmm, your way of looking at Q does not make sense to me. Q-values are essentially a description of resonance circuits. This can be applied to second-order filters, or closed box designs, but hardly to a reflex box. How do you come up with the number 1.2 for your system? Even if we assume a closed box, the Qtc would be 0.35*sqrt(1+135/55)=0.65.
just missed your prev comment......Yes snap..... a Q of 0.65 with my closed box is bang on......a bit ultra purist with low freq.....it sounds ok when cabinet put into a corner. I still prefer the reflex....with the bass eq a touch into the minus.
ps. I may be touch difficult getting over with the jargon, as I'm half jerry/ UK..,........pref UK
rich
ps. I may be touch difficult getting over with the jargon, as I'm half jerry/ UK..,........pref UK
rich
Dick Olsher, the designer of the Poly Natalia, and the Basszilla among others, is now speccing the Eminence Magnum 15HO as the Basszilla bass driver. He likes it a lot. It has been mentioned in this thread varius times because it has ALL the features that seem to indicate quality. Better, it seems to sell at Parts Express for around $250- a reasonable price for such a quality item. Anyway at least we have a report from someone that has heard 'em...
Mark
the features that seem to indicate quality. Better, it seems to sell at Parts Express for around $250- a reasonable price for such a quality item. Anyway at least we have a report from someone that has heard 'em...Mark
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