You can cut out notches but you can't boost. Or to put it another way, you can notch out peaks, but you can't boost notches.
Steve/bluewizard
Lots of info here but still not sure where I am.
Just purchased four 8" speakers (woofers), 4 ohm with a 92.9 DB sensitivity at 2.83/1M. Planned on doing two in series for each speaker for an 8 ohm load to the amp.
This is a three way design. The midrange is an 8 ohm with 89.4 DB sensitivity at 2.83/1M. The tweeter is 8 ohm 94 DB sensitivity at 2.83/1M, so I figured I would have to pad down the tweeter and I could equalize in the midrange as I suspect with two woofer in series for an 8 ohm load that I would be knocking 3 db off the sensitivity at 2.83/1M. leaving me with a combined 89.9 sensitivity.
Guess I'll find out soon enough, just purchased the latest version of Sound Easy as my older parallel port key version was not working right any more.
I'm just hoping I didn't screw up on the purchase.
Just purchased four 8" speakers (woofers), 4 ohm with a 92.9 DB sensitivity at 2.83/1M. Planned on doing two in series for each speaker for an 8 ohm load to the amp.
This is a three way design. The midrange is an 8 ohm with 89.4 DB sensitivity at 2.83/1M. The tweeter is 8 ohm 94 DB sensitivity at 2.83/1M, so I figured I would have to pad down the tweeter and I could equalize in the midrange as I suspect with two woofer in series for an 8 ohm load that I would be knocking 3 db off the sensitivity at 2.83/1M. leaving me with a combined 89.9 sensitivity.
Guess I'll find out soon enough, just purchased the latest version of Sound Easy as my older parallel port key version was not working right any more.
I'm just hoping I didn't screw up on the purchase.
Your 4ohms bass speakers are rated as 92.9dB/2.83V @ 1m
That is equivalent to 92.9dB/2W @ 1m and that equals 89.9dB/W @ 1m
Now put them in series so that each receives 1/2W, then each will output 86.9dB/1/2W @ 1m
But you have two of them getting you back to 1W into the pair giving a total output of 89.9dB/W @ 1m
In addition, over the frequency range where they are considered to be coupled, you get upto 3dB more output. So at low frequencies you have 92.9dB/W @ 1m and above the coupled range you have 89.9dB/W @ 1m
Unfortunately the pair will have some beaming due to the null and peak of the interference patterns. That beam will also have the same +3dB when the two drivers are pointing directly at the listener, or measuring mic.
You may need somewhere between +3dB and +6dB to take account of the loss due to a small baffle (Pi/4 loading instead of Pi/2 loading that all manufacturers use).
Bass = 89.9dB/W ranging up to 92.9dB/W
Mid = 89.4dB/W
Treble = 94dB/W
The only speaker that will not need padding is the Mid.
The extra sensitivity of the Bass already makes up for some, or most of the baffle step loss. Get this tuned in and you may find the final Bass response/sensitivity equals the Mid driver.
Both the Treble and the Bass will need some padding down (or use dedicated amplifiers with adjustable sensitivity).
With smaller drivers (meaning not 10", not 12', not 15") and modern narrow cabinets, if the crossover is chosen wisely it can be below the baffle step.
For example, using 8" drivers and assuming a 10" Wide baffle, the step frequency will be 456hz (roughly). If you are using a Low/Mid crossover in the roughly 300hz range, Baffle Step is not really a problem for the low-bass.
Though a bit more complex than this, you can get an estimate by this formula -
F = 380 / Bw
Where -
F = the baffle step frequency
380 = a constant derived from solving a more complex equation
Bw = Baffle Width in FEET
An alternative to Crossover Baffle Step correction, which usually involve reducing the woofer above the Baffle Step, you can boost the bass output by using a Half-Way system.
Adding a second identical driver running in parallel with the main bass driver but only covering the range for the lowest frequency up to the Baffle Step.
This image was created for another purpose, but in this case, we would assume the Baffle Step was around 200hz.
Steve/bluewizard
Let me tell you my series parallel speaker experience.
Since I was not happy with the volme level I got from my Fostex 8" full rangers in big boxes powered by my new 3.5 watt 2A3 SE tube amp I thought of making a speaker of higher sensitivity.
I connected a pair of 8" drivers each of 8 ohms to get 16 ohms. Then added a second pair on parallel to this to make it 8 ohms again. Now the cone area is 4 times the area of a single driver.
Two pairs of these combimations were fitted to two 18" by 54" tall open baffles and placed against the side walls close to the two corners of the listening room.
The resultant combination was extreamly loud because the sensity had increased by many dB.
The bass was good. The drivers did not bottom with the 3.5 watts in the un damped open baffle although they bottomed at higher wattages giving distorsion.But then the speaker was so loud you could not remain in the room.
Since I was not happy with the volme level I got from my Fostex 8" full rangers in big boxes powered by my new 3.5 watt 2A3 SE tube amp I thought of making a speaker of higher sensitivity.
I connected a pair of 8" drivers each of 8 ohms to get 16 ohms. Then added a second pair on parallel to this to make it 8 ohms again. Now the cone area is 4 times the area of a single driver.
Two pairs of these combimations were fitted to two 18" by 54" tall open baffles and placed against the side walls close to the two corners of the listening room.
The resultant combination was extreamly loud because the sensity had increased by many dB.
The bass was good. The drivers did not bottom with the 3.5 watts in the un damped open baffle although they bottomed at higher wattages giving distorsion.But then the speaker was so loud you could not remain in the room.
Srian, you may like to look at this site....................
Efficiency and sensitivity conversion - loudspeaker percent and dB per watt and meter loudspeaker efficiency versus sensitivity vs speaker sensitivity 1 watt = 2,83 volt box chart - sengpielaudio Sengpiel Berlin
C.M
Efficiency and sensitivity conversion - loudspeaker percent and dB per watt and meter loudspeaker efficiency versus sensitivity vs speaker sensitivity 1 watt = 2,83 volt box chart - sengpielaudio Sengpiel Berlin
C.M
very close but not identical
So I'm looking at using two very similar but not identical mid-woofers in a single parallel circuit. Not entirely kosher - I know.
The drivers will have separate reflex enclosures one tuned to 45+/- Hz and the other tuned to 65+/- Hz as recommended by the manufacturer.
Looking at the two drivers in question (spec sheets attached), aren't their parameters so close that there may be little cause for concern about putting them in the same parallel circuit?
I know I could do a 2.5 way system but I'd rather not...
So I'm looking at using two very similar but not identical mid-woofers in a single parallel circuit. Not entirely kosher - I know.
The drivers will have separate reflex enclosures one tuned to 45+/- Hz and the other tuned to 65+/- Hz as recommended by the manufacturer.
Looking at the two drivers in question (spec sheets attached), aren't their parameters so close that there may be little cause for concern about putting them in the same parallel circuit?
I know I could do a 2.5 way system but I'd rather not...
Being in two separate enclosures, the only concern is how close are their frequency responses. Sensitivity of both drivers are within 1 dB, which is OK, but their frequency responses may differ, especially around crossover frequency. If their frequency responses are close enough, then you can parallel them and make a single crossover filter for both drivers.
PHL is notorious for not stating the frequency response of their drivers. It is frustrating, at least.
PHL is notorious for not stating the frequency response of their drivers. It is frustrating, at least.
I'd hate to bother with an old thread, but what about wiring two sets of series woofers in parallel? The impedance should stay the same, what about the sensitivity?
If I have 4 drivers that are identical and 88db @2.83 each, and I wire them as such, what is the overall sensitivity? Still 88db?
If I have 4 drivers that are identical and 88db @2.83 each, and I wire them as such, what is the overall sensitivity? Still 88db?
An externally hosted image should be here but it was not working when we last tested it.
That is correct for one pair serially connected drivers. But here we have two pairs of drivers in parallel.
Should be, if my information is correct.
pair1: 82dB + 82dB = 82dB (in series, sees no increase in sensitivity)
pair2: 82dB + 82dB = 82dB (in series, sees no increase in sensitivity)
pair1 + pair2: 82dB + 82dB = 85dB (parallel gets +6 for cone area and extra power)
Your math is wrong. Addition of two random noise signals is +3dB in power, but here we have two signals in phase, so it is +6dB:
pair1: 82dB+82dB=88 dB
pair2: 82dB+82dB=88 dB
pair1 + pair2 = 88dB+88dB = 94 dB
