Hello
I have a pair of Dynaudio 17W75 woofer and D-28/2 tweeter.
I like the Dynaudio 17W75, it have very clean sound, but it have only 85dB for the SPL at 1W/1m , I would like a loudspeaker box who would boost the overall efficiency of my Dynaudio 17W75 and having a clean sound.
It seem that horn or transmission line speaker will not work since the Qts are too high, do using the variovent (or similar product) would be the solution ?
What size and type of box would be best with a Dynaudio 17W75 and a variovent ?
Here's the spec of my Dynaudio;
Dynaudio 17W-75
Dia 6.5"
Power 150W
Z 8 ohm
SPL 85dB
Fs 39hz
Vas cu ft .664
Qts 0.74
xmax 0.217"
Thank
Gaetan
I have a pair of Dynaudio 17W75 woofer and D-28/2 tweeter.
I like the Dynaudio 17W75, it have very clean sound, but it have only 85dB for the SPL at 1W/1m , I would like a loudspeaker box who would boost the overall efficiency of my Dynaudio 17W75 and having a clean sound.
It seem that horn or transmission line speaker will not work since the Qts are too high, do using the variovent (or similar product) would be the solution ?
What size and type of box would be best with a Dynaudio 17W75 and a variovent ?
Here's the spec of my Dynaudio;
Dynaudio 17W-75
Dia 6.5"
Power 150W
Z 8 ohm
SPL 85dB
Fs 39hz
Vas cu ft .664
Qts 0.74
xmax 0.217"
Thank
Gaetan
Greets!
FYI, more complete published/calc'd specs:
Fs = 39 Hz
Vas = 0.663916 ft^3 (18.8 L)
Qes = 1.12
Qms = 2.18
Qts = 0.74
Xmax = 0.1083" (2.75 mm)
BL = 4.3 N/A (calc'd 4.661 - 4.694 depending on 'c', 'po' used, so some thing's amiss in these specs)
Sd = 18.6"^2 (120 cm)
Dia = 4.866" (12.361 cm)
Pe = 150 W
Re = 5.5 ohms
SPL = 85 dB/W/m (calc'd 81.84 dB)
According to some old Dynaudio specs, they recommend 14 L/52 Hz F3 with a variovent, but if this is acceptable, then it's medium high Qts makes it suitable for an end loaded max flat impedance TL that's much better damped:
L = 60.042"
CSA = 38.504"^2 (7" dia.)
stuffing = 1.0 lb/ft^3 polyfil shown
Round up the dims to your preferred units, fold it as required to get the desired listening height with the tweeter on top and stuff to suit.
GM
FYI, more complete published/calc'd specs:
Fs = 39 Hz
Vas = 0.663916 ft^3 (18.8 L)
Qes = 1.12
Qms = 2.18
Qts = 0.74
Xmax = 0.1083" (2.75 mm)
BL = 4.3 N/A (calc'd 4.661 - 4.694 depending on 'c', 'po' used, so some thing's amiss in these specs)
Sd = 18.6"^2 (120 cm)
Dia = 4.866" (12.361 cm)
Pe = 150 W
Re = 5.5 ohms
SPL = 85 dB/W/m (calc'd 81.84 dB)
According to some old Dynaudio specs, they recommend 14 L/52 Hz F3 with a variovent, but if this is acceptable, then it's medium high Qts makes it suitable for an end loaded max flat impedance TL that's much better damped:
L = 60.042"
CSA = 38.504"^2 (7" dia.)
stuffing = 1.0 lb/ft^3 polyfil shown
Round up the dims to your preferred units, fold it as required to get the desired listening height with the tweeter on top and stuff to suit.
GM
Attachments
GM said:
Hi
"An end loaded max flat impedance TL", seem interesting, I never made a TL, where can I find a plans of that transmision line for my Dynaudio ?
I was think that the Dynaudio 17W75 Qts was to high for a good transmision line loudspeaker ?
There was the BassTuba but some guys try it with high Qts woofer and they told me that the bass was muddy.
Thank
Gaetan
Greets!
I just 'ran the numbers' and loaded them in MJK's Mathcad program to get a sim for you, so no drawings. It's up to you to turn them into a cab that suits your sense of shape/style.
The BassTuba is designed for a fairly low Q driver IIRC, so no, it won't do well with a high Q driver. Regardless, horns need to be designed around the driver and you can make good performing horns with high Q drivers, but they are huge compared to ones designed for a low Q driver and not as efficient, so normally not a good choice.
GM
I just 'ran the numbers' and loaded them in MJK's Mathcad program to get a sim for you, so no drawings. It's up to you to turn them into a cab that suits your sense of shape/style.
The BassTuba is designed for a fairly low Q driver IIRC, so no, it won't do well with a high Q driver. Regardless, horns need to be designed around the driver and you can make good performing horns with high Q drivers, but they are huge compared to ones designed for a low Q driver and not as efficient, so normally not a good choice.
GM
L = 60.042"
CSA = 38.504"^2 (7" dia.)
stuffing = 1.0 lb/ft^3 polyfil shown
------
Hi
What is CSA ?
Thank
Gaetan
CSA = 38.504"^2 (7" dia.)
stuffing = 1.0 lb/ft^3 polyfil shown
------
Hi
What is CSA ?
Thank
Gaetan
planet10 said:
Works for me, thanks for the help! Maybe one of these days before Oldtimer's disease finishes me off I'll learn a Cad program.
planet10 said:
That's about right for a < 5" effective diameter, but I don't really care about the nominal diameter for box design.........
GM said:
OK, that is the actual cone .... by the time you add the basket you are up in the 6.5" diameter neighborhood -- we were just talking different diameters.
dave
GM said:
🙂
And i was asking because i was drawing up a representation of the driver for the box.
dave
GM said:
Then the driver in the drawing is a tad small and it may be necessary to offset it just to make it fit.
dave
Hello
Very good work and drawing.
Do I put the 1.0 lb of polyfil stuffing near the woofer or all the way inside the box ?
I'm a nul in math, I did discover the Martin J. King web page but I still try to understand all those math he use there, but since I'm french speaking it's a bit difficult for me to read long english technical texts.
Thank you
Gaetan
Very good work and drawing.
Do I put the 1.0 lb of polyfil stuffing near the woofer or all the way inside the box ?
I'm a nul in math, I did discover the Martin J. King web page but I still try to understand all those math he use there, but since I'm french speaking it's a bit difficult for me to read long english technical texts.
Thank you
Gaetan
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