I have been looking at woofers for a 3 way system and am quite keen on the SPH-275C from Monacor. I am mainly attracted to it because it seems to have very optimal parameters for a TL design (and after building a TL sub I have decided I like the sound they give 
).
http://www.monacor.com/en/produktseite_suche.php?artid=3735&spr=EN&typ=full
In a 3 way I would be intending to cross it low at around 200-250Hz, so it will mainly be active in subwoofer region (hence why it's posted here).
Really I am wondering just how well it would work (frequency response) but don't have the design software. Also the size it would need to be. My sub with 2x6" is quite large compared to the drivers so one (or a pair as it would be) with 10" will presumably be larger. VAS is higher and resonance is lower so presumably a larger area and longer line result. Anyone thoughts?
). http://www.monacor.com/en/produktseite_suche.php?artid=3735&spr=EN&typ=full
In a 3 way I would be intending to cross it low at around 200-250Hz, so it will mainly be active in subwoofer region (hence why it's posted here).
Really I am wondering just how well it would work (frequency response) but don't have the design software. Also the size it would need to be. My sub with 2x6" is quite large compared to the drivers so one (or a pair as it would be) with 10" will presumably be larger. VAS is higher and resonance is lower so presumably a larger area and longer line result. Anyone thoughts?
Yes, I hear MJK is where it's at with transmission lines. Are they literally "worksheets" though? What I've read on his site, being honest, is mostly above me. It goes into great depth. Does he have a program to model in? Such as you put in driver parameters and various line models and it shows frequency response, excursion etc? Something interactive like that. Scottmoose came up with a frequency response graph for the Morel woofers in a TL and I think it was using MJKs "worksheets".
Vas is 100L and this looks relatively low for a 10" driver (I think). Would it end up as a wardrobe ?
Vas is 100L and this looks relatively low for a 10" driver (I think). Would it end up as a wardrobe
?
A good choice in a 10 inch would be the Peerless S263SWR3908.
http://www.tymphany.com/datasheet/pdf/pl/830668.pdf
It has a low Fs (33), good response up tp 1K and a Qts of .51. Also pretty cheap - $70.00 here.
Make an excellent TL sub.
http://www.tymphany.com/datasheet/pdf/pl/830668.pdf
It has a low Fs (33), good response up tp 1K and a Qts of .51. Also pretty cheap - $70.00 here.
Make an excellent TL sub.
Well I havent heard that you cant use low Qts drivers for a TL - Generally speaking high Qts drivers (.4+) will only work in sealed enclosures, now considering a TL works more like a vented box then it would make sense that low Qts drivers are better suited (0.3-0.4). I have had a lot of success using just such drivers.
I have always designed TLs (actually quarter wave) using the basic 1/4 wavelength of Fs (assuming tuning ratio of 1) & a taper of 1.25 to 1, using the drivers Sd to calc cross sectional area.
I would suggest keeping the folds very simple & minimal, the best sub I built (which I currently use) has a single 'fold' - this alos meant it was very easy to tune with damping.
The Monacor driver you have chosen looks fine + I have always liked carbon fibre for bass duties.
Andrew.
I have always designed TLs (actually quarter wave) using the basic 1/4 wavelength of Fs (assuming tuning ratio of 1) & a taper of 1.25 to 1, using the drivers Sd to calc cross sectional area.
I would suggest keeping the folds very simple & minimal, the best sub I built (which I currently use) has a single 'fold' - this alos meant it was very easy to tune with damping.
The Monacor driver you have chosen looks fine + I have always liked carbon fibre for bass duties.
Andrew.
hi
i have read most of the TL documents of Dr. Martin J Kings
i dont think Vas has anything to do with Tl length
only Freq cutoff plays role, refer to TL line Martin J Kings Alignment_Tables[1].PDF for more
Plus i would like to share what Dr. Martin J Kings told me on weekend -
Bass reflex enclosures and TL are more similar then most people admit. I think that the reason some people like a TL better then a bass reflex is for two reasons.
1. The fiber damping removes any ring and boomy response. It makes the transition into the 24 db/octave rolloff more gradual so a resonant note at the tuning frequency does not occur. The fiber also helps kill any higher order resonances in the enclosure which in general leads to a cleaner mid bass response.
2. Tuning of the enclosure is not as critical. Basically a bass reflex box can be easily mistuned, the port is a little too long or the box volume is slightly off. This can lead to either boomy bass or weak bass. A TL seems to be a little more forgiving of errors in the cabinet design and it can easily be adjusted by adding or removing some fiber stuffing.
richie00boy said:
i have read most of the TL documents of Dr. Martin J Kings
i dont think Vas has anything to do with Tl length
only Freq cutoff plays role, refer to TL line Martin J Kings Alignment_Tables[1].PDF for more
Plus i would like to share what Dr. Martin J Kings told me on weekend -
Bass reflex enclosures and TL are more similar then most people admit. I think that the reason some people like a TL better then a bass reflex is for two reasons.
1. The fiber damping removes any ring and boomy response. It makes the transition into the 24 db/octave rolloff more gradual so a resonant note at the tuning frequency does not occur. The fiber also helps kill any higher order resonances in the enclosure which in general leads to a cleaner mid bass response.
2. Tuning of the enclosure is not as critical. Basically a bass reflex box can be easily mistuned, the port is a little too long or the box volume is slightly off. This can lead to either boomy bass or weak bass. A TL seems to be a little more forgiving of errors in the cabinet design and it can easily be adjusted by adding or removing some fiber stuffing.
I'm judging by the guideline set out here:
http://www.diysubwoofers.org/tls/tls1.htm
to which the SPH-275C fits quite closely to.
Interestingly this driver simulates poorly (on WinISD) in a ported box with a -3db point around 50Hz. This doesn't seem very low for a 10" and many 6" simulate with lower F3 points. Hopefully it works much
better in a TL or I'm missing something on WinISD. With a 31Hz Fs it should be capable of going pretty smoothly to the low 20's in a TL i'd imagine? The response looks quite smooth right up past my expected crossover frequency so that shouldn't be much of an issue.
Andrew, you say you like carbon fibre for bass; this is encouraging. What characteristics does it give generally speaking?
http://www.diysubwoofers.org/tls/tls1.htm
to which the SPH-275C fits quite closely to.
Interestingly this driver simulates poorly (on WinISD) in a ported box with a -3db point around 50Hz. This doesn't seem very low for a 10" and many 6" simulate with lower F3 points. Hopefully it works much
better in a TL or I'm missing something on WinISD. With a 31Hz Fs it should be capable of going pretty smoothly to the low 20's in a TL i'd imagine? The response looks quite smooth right up past my expected crossover frequency so that shouldn't be much of an issue.
Andrew, you say you like carbon fibre for bass; this is encouraging. What characteristics does it give generally speaking?
DrEM,
To make up for my previous blunder I'll try to help out here.
The drivers Fs is 31, use that and the lines taper ratio to get the overall line length.
Using Martin's alignment tables, I get 89 inches with a 3:1 taper for this frequency.
To determine the closed end (So) cross section involves some math. Using the drivers Qts to get variable Dr from table 3: Dr= .1313
Using Fs and taper ratio to get variable Dz from table 2: Dz= 41.73.
Driver Bl is 13.83
Driver Sd is .0363 (m^2)
Driver Re is 6.1
Formula: So/Sd=p*c*Sd*Dz*Dr*Re/(Bl)^2
So/Sd=2.62
So=951 cm^2
That's about 12" x 12" for the cross section line start.
Driver should be somewhere around 1/5 of the way down the line from the start.
The open end will be 317 cm^2. That's about 12" x 4"
Increasing the taper to 4:1 or higher will reduce the line length but could cause vent noise, as the open end gets smaller.
To make up for my previous blunder I'll try to help out here.
The drivers Fs is 31, use that and the lines taper ratio to get the overall line length.
Using Martin's alignment tables, I get 89 inches with a 3:1 taper for this frequency.
To determine the closed end (So) cross section involves some math. Using the drivers Qts to get variable Dr from table 3: Dr= .1313
Using Fs and taper ratio to get variable Dz from table 2: Dz= 41.73.
Driver Bl is 13.83
Driver Sd is .0363 (m^2)
Driver Re is 6.1
Formula: So/Sd=p*c*Sd*Dz*Dr*Re/(Bl)^2
So/Sd=2.62
So=951 cm^2
That's about 12" x 12" for the cross section line start.
Driver should be somewhere around 1/5 of the way down the line from the start.
The open end will be 317 cm^2. That's about 12" x 4"
Increasing the taper to 4:1 or higher will reduce the line length but could cause vent noise, as the open end gets smaller.
Thanks for that
Theres a few things i'm still wondering about. Is it normal practice to have the tuning frequency at the drivers Fs? What would the F3 be roughly, somewhere below the tuning frequency i'd imagine? Strong response into the low 20's is quite important if possible (even if that is only "in room").
A lot of frequency response graphs of TL designs show quite severe looking ripples above the tuning frequency (starting at 3 times that freq?). I'd need a flat response up past my crossover frequency to ensure a good crossover; how can I ensure I don't get the ripples? I think it was to do with driver placement (which you suggest as about 1/5th down) but would it need to be quite precise to minimise any potential response anomalies? I suspect intercative work with a program would be required to fully understand the consequences (just as you would with baffle step).
Thanks again
Theres a few things i'm still wondering about. Is it normal practice to have the tuning frequency at the drivers Fs? What would the F3 be roughly, somewhere below the tuning frequency i'd imagine? Strong response into the low 20's is quite important if possible (even if that is only "in room").
A lot of frequency response graphs of TL designs show quite severe looking ripples above the tuning frequency (starting at 3 times that freq?). I'd need a flat response up past my crossover frequency to ensure a good crossover; how can I ensure I don't get the ripples? I think it was to do with driver placement (which you suggest as about 1/5th down) but would it need to be quite precise to minimise any potential response anomalies? I suspect intercative work with a program would be required to fully understand the consequences (just as you would with baffle step).
Thanks again
Dr.EM said:
From my experience a TL is not going to do much below tuning, (I'm guessing 4th order roll-off) mine use an 8" with Fs & tuning of 35hz, they have very little output at 30hz and none at 20hz. The driver you are looking at is a woofer, & will probably work well up into the high range, which I understand is what you wanted.
For a floorstander response down to 40hz (the lowest note on a bass guitar is 41hz) is quite acceptable. Plus tuning a TL to 20hz is going to be a really long line (1/4 wavelength is 4.3m compared with 30hz = 2.8m).
If you want 20hz build a separate subwoofer (using a high mass, low fs, driver).
eg. http://www.monacor.de/en/produktseite_monacor.php?artid=2072&spr=EN&typ=u
Stick with your plans, Andrew.
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