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Get familiar with the reaction system: Introducing the Reaction System
Realistic 40-1015
Old school, untreated paper coned acoustic suspension woofers. Hard to find, so I snapped up a pair advertised as "newly foamed" when I got a chance. Other than one of the woofers looking a little messy, they are fine.
Copy paste specs from Radio Shack site:
Sample 2:
Fairly sensitive for an 8 ohm woofer, moderately high Qts along with high compliance. In one cubic foot sealed, one could reasonably expect output close to 100db at 25 watts with very little breaching of Xmax (although it does not have a bumped back plate so it would go ugly in a hurry). Impedance curve indicates a breakup around 3K.
So here I have a 91db driver with almost 5mm of coil travel one-way that will install into a 25L sealed and stuffed enclosure yielding a Qtc of around 0.76, F3/6/10 of 65/52/41, and at 25 watts of input will play to almost 100db after baffle step losses.
Here is where it gets fun, however, and a nod to our ancestors is in order... Baffle step losses were not generally a consideration back in the day. It was understood, but speakers were generally built to be pushed against the damn wall, anyways - right? So if a guy were to build a cabinet using these, ignore modern convention that dictates we must compensate for baffle step losses, and push the speakers into, say the living room corners what would our effective output and system F3/6/10 be? I am guessing we could hit peaks close to 103, or 104 db at 40Hz.
Basic model using WBCD:
And Excursion at 25 watts:
Now, I normally listen no louder than 85db peaks as I suspect most of us here do. Rarely I will twist the knob to hit 90db peaks, and outside of some car audio adventures over the years (and a memorable Barbie Girl demo), I never listen to 100db peaks. So yeah - I would consider this woofer remarkably well designed for the time and place it came from. 10-20 watt receivers were the norm, rumble filters everywhere, and speakers shoved in corners.
I now return you to your regularly scheduled content - have a great Saturday!
Copy paste specs from Radio Shack site:
Nominal Impedance:...................................................8 Ohms
DC Resistance (Re):..................................................6 Ohms
Free Air Resonance (Fs):............................................41.9 Hz
Suspension Compliance (CMS):......................................0.93 mm/N
Equivalnt Air Volume (VAS):...................................0.042 m cubed
Effective Diameter (D):...............................................16 cm
Effective Area (SD):.........................................201 cm squared
Moving Mass (Mms):..................................................15.6 gm
Mechanical Q (QMS):....................................................3.61
Electrical Q (QES):....................................................0.65
Total Q (QTS):.........................................................0.55
Peak Power Rating:.....................................................50 W
Peak to Peak Linear Excursion (Xd):.................................9.65 mm
Gap Flux Density (Bg):.........................................1.0899 Tesla
Sample 1:
Sample 1:
Loudspeaker parameters:
Fs = 43.40 Hz
Re = 5.89 ohms[dc]
Le = 178.81 uH
L2 = 547.25 uH
R2 = 15.28 ohms
Qt = 0.54
Qes = 0.64
Qms = 3.59
Mms = 16.04 grams
Rms = 1.217025 kg/s
Cms = 0.000838 m/N
Vas = 47.60 liters
Sd= 201.06 cm^2
Bl = 6.343014 Tm
ETA = 0.58 %
Lp(2.83V/1m) = 91.10 dB
Added Mass Method:
Added mass = 30.00 grams
Diameter= 16.00 cm
Sample 2:
Loudspeaker parameters:
Fs = 42.05 Hz
Re = 5.85 ohms[dc]
Le = 163.84 uH
L2 = 528.37 uH
R2 = 14.91 ohms
Qt = 0.55
Qes = 0.65
Qms = 3.55
Mms = 15.12 grams
Rms = 1.125066 kg/s
Cms = 0.000948 m/N
Vas = 53.81 liters
Sd= 201.06 cm^2
Bl = 5.985065 Tm
ETA = 0.59 %
Lp(2.83V/1m) = 91.17 dB
Added Mass Method:
Added mass = 30.00 grams
Diameter= 16.00 cm
Fairly sensitive for an 8 ohm woofer, moderately high Qts along with high compliance. In one cubic foot sealed, one could reasonably expect output close to 100db at 25 watts with very little breaching of Xmax (although it does not have a bumped back plate so it would go ugly in a hurry). Impedance curve indicates a breakup around 3K.
So here I have a 91db driver with almost 5mm of coil travel one-way that will install into a 25L sealed and stuffed enclosure yielding a Qtc of around 0.76, F3/6/10 of 65/52/41, and at 25 watts of input will play to almost 100db after baffle step losses.
Here is where it gets fun, however, and a nod to our ancestors is in order... Baffle step losses were not generally a consideration back in the day. It was understood, but speakers were generally built to be pushed against the damn wall, anyways - right? So if a guy were to build a cabinet using these, ignore modern convention that dictates we must compensate for baffle step losses, and push the speakers into, say the living room corners what would our effective output and system F3/6/10 be? I am guessing we could hit peaks close to 103, or 104 db at 40Hz.
Basic model using WBCD:
And Excursion at 25 watts:
Now, I normally listen no louder than 85db peaks as I suspect most of us here do. Rarely I will twist the knob to hit 90db peaks, and outside of some car audio adventures over the years (and a memorable Barbie Girl demo), I never listen to 100db peaks. So yeah - I would consider this woofer remarkably well designed for the time and place it came from. 10-20 watt receivers were the norm, rumble filters everywhere, and speakers shoved in corners.
I now return you to your regularly scheduled content - have a great Saturday!
I have a signature.
Comments
That Cms! Qes/Qms!
And imagine that.... A strong BL too. No wonder the 91dB.
I wish a true AS option would be available on some modern drivers.