Okay, I'm here because I want to do what I'm doing right and I am completely unsure of how the "dB" spls are measured for speakers in their specs
Basically all I'm doing is making small 2-way speakers for a larger project and this is what I've run into:
Tweeter:
90.5 dB
10/20W rms and peak
6 Ohm
Mid/sub:
82 dB
15/30W rms and peak
8 Ohm
So if all I needed to do was attenuate the tweeters output down 8.5 dB fine, no problem, there are online calculators for that. However, presumably at maximum volumes if the box is receiving 15W rms then the attenuation will not be correct. Is this the right way to be thinking about this? I guess my problem is that the speakers have different voltage ratings so how is it that I can attenuate the tweeter and expect it to be fine when in reality it won't be getting 10 watts but rather 15? Since they have differing impedances the voltage that they both receive will cause the tweeter to have more power either way.
Any help and insight would be wonderful
Basically all I'm doing is making small 2-way speakers for a larger project and this is what I've run into:
Tweeter:
90.5 dB
10/20W rms and peak
6 Ohm
Mid/sub:
82 dB
15/30W rms and peak
8 Ohm
So if all I needed to do was attenuate the tweeters output down 8.5 dB fine, no problem, there are online calculators for that. However, presumably at maximum volumes if the box is receiving 15W rms then the attenuation will not be correct. Is this the right way to be thinking about this? I guess my problem is that the speakers have different voltage ratings so how is it that I can attenuate the tweeter and expect it to be fine when in reality it won't be getting 10 watts but rather 15? Since they have differing impedances the voltage that they both receive will cause the tweeter to have more power either way.
Any help and insight would be wonderful
Hi,
The tweeter will receive far less power than the bass/mid
due to the music programmes spectral power envelope.
Its not a concern, its entirely usual.
Nevermind the fact that if you attenuate the tweeter by say
6dB, the power handling of the tweeter section quadruples.
In attenuating the tweeter by 8.5dB you can choose any
impedance for the treble section you like, but its best to
go with an L-pad, I'd say about 4R in series with the
tweeter and about 6R in parallel.
rgds, sreten.
The tweeter will receive far less power than the bass/mid
due to the music programmes spectral power envelope.
Its not a concern, its entirely usual.
Nevermind the fact that if you attenuate the tweeter by say
6dB, the power handling of the tweeter section quadruples.
In attenuating the tweeter by 8.5dB you can choose any
impedance for the treble section you like, but its best to
go with an L-pad, I'd say about 4R in series with the
tweeter and about 6R in parallel.
rgds, sreten.
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Attenuation
Sreten is right.
Don't attenuate the tweeter more than 6db.
I generally consider the half of the sensitivity gap.
So 3R3 in series and around 10R / 12R in parallel.
Or, as correctly suggested by Sreten, 4R in series and 6R / 8R in parallel.
This seems to be the right room of manoeuvre.
Hi from Italy
Sreten is right.
Don't attenuate the tweeter more than 6db.
I generally consider the half of the sensitivity gap.
So 3R3 in series and around 10R / 12R in parallel.
Or, as correctly suggested by Sreten, 4R in series and 6R / 8R in parallel.
This seems to be the right room of manoeuvre.
Hi from Italy
Hi,
I didn't say that. 4R in series and 6R in parallel for a 6R tweeter
is -7.35dB, going to 5R gives -8.5dB and 8R treble impedance.
For a 82dB bass/mid (? very low) you''ll need even more
attenuation due to BSC (baffle step correction), unless
you go 2.5 way TMM or 2 way MTM 4ohms in the bass.
rgds, sreten.
Pardon
Pardon
My mistake... I did not notice that the tweeter 6R and not 8R.
Anyway, my mind remains the same: not to compensate the whole nominal gap, not to lower sensitivity too much, trying to find the best compromise. Of course, it would depend on amp(s) to supply the required power. And this can be another question point...
D.
Pardon
My mistake... I did not notice that the tweeter 6R and not 8R.
Anyway, my mind remains the same: not to compensate the whole nominal gap, not to lower sensitivity too much, trying to find the best compromise. Of course, it would depend on amp(s) to supply the required power. And this can be another question point...
D.
I guess my biggest worries are that the power handling differences of the drivers could be giving me the wrong idea. If the specs on the tweeter are saying it is louder is this taking into consideration its power handling? Because if I were to feed the tweeter and the mid with the same power then the tweeter would be even louder with respect to the mid, correct?
Another way I could explain this is say:
the source being fed to the tweeter is 15wrms
I decided to attenuate the signal going to the tweeter down to 10wrms
now looking at the specs, it would appear that I still have the same problem:
because the tweeter is at its power handling and will be 90.5 dB
and the mid will be at 15wrms and be 82 dB
so is the power handling something else that I need to consider when trying to match these with an l-pad?
Thank you!
Another way I could explain this is say:
the source being fed to the tweeter is 15wrms
I decided to attenuate the signal going to the tweeter down to 10wrms
now looking at the specs, it would appear that I still have the same problem:
because the tweeter is at its power handling and will be 90.5 dB
and the mid will be at 15wrms and be 82 dB
so is the power handling something else that I need to consider when trying to match these with an l-pad?
Thank you!
Hi,
If you L-pad the tweeter with 5R in series and 6R in parallel,
for -8.5dB attenuation, the tweeter will never see more
than ~ 4W with 15W drive.
Forget about power handling for matching sensitivity.
rgds, sreten.
If you L-pad the tweeter with 5R in series and 6R in parallel,
for -8.5dB attenuation, the tweeter will never see more
than ~ 4W with 15W drive.
Forget about power handling for matching sensitivity.
rgds, sreten.
There are some things to consider to keep your thinking straight. Your amplifier is not a power or watt generator. It outputs a constant voltage (at a fixed volume setting). The watts of power you will get is dependent on the resistance or more accurately the impedance of the load. A lower impedance means you will get more power delivered.
The standard for rating speaker impedance is to give the dB it produces when supplied with a 2.83 V source (1 watt into 8 ohms nominal). So in your case without correction one speaker will be producing 90.5 dB and the other 82 dB. If you put a resistor in series with the tweeter, the 2.83 volts from the amp remains unchanged. However the voltage drop is now divided by the series resistor and the speaker. If you put a 6 ohm resistor in you will divide the voltage in half for example. The calculator at the link below suggests you would need a single 10 ohm speaker in series, or an L pad with 3.8 ohms in series and 3.6 ohms in parallel. Keep in mind you will have a higher load on the amplifier if you go the L pad route because now you will have 2.83 volts feeding 6 ohms instead of 2.83 volts feeding 16 ohms (6+10).
Either way you are putting power into the resistors and your tweeter circuit power handling goes up. It is not your limitation. Keep in mind that a 80 dB sensitivity speaker is not very high and you are not going to produce high volumes. If you want more you will want to find a woofer with higher sensitivity -- closer to 90 dB.
L pad calculator - attenuation dB damping impedance decibel loudspeaker speaker voltage divider - sengpielaudio Sengpiel Berlin
I'd like to bring back this thread, since I have a new design, and its my first crossover so I want to make sure I have this down.
2 way, 2nd order linkwitz-riley
sub
4" HIVI Bn4
8Ω 85 dB 2.83V(1W)/1M
tweet
HIVI TN25
5Ω 89 dB 1W/1M
Okay, my concerns.
I have an online lpad calculator I am familiar and comfortable using, HOWEVER, what is the actual sensitivity difference in the drivers. Since the tweeter is 5 Ω if i just hooked them up to the same power (voltage) wouldn't the tweeter technically be louder since it's a lower impedance and thus a higher current? so what I'm saying is, yes if they both have 1w of power or however those 2 numbers were measured, then I'm sure their output is 85 and 89 dB but since they're at the same source they're actually receiving different power.. how do I account for this, should i add a 3Ω resistor in series to the tweeter so it has the same seen impedance as the woofer.
if someone takes the time to reply and explain a little, then thank you!
2 way, 2nd order linkwitz-riley
sub
4" HIVI Bn4
8Ω 85 dB 2.83V(1W)/1M
tweet
HIVI TN25
5Ω 89 dB 1W/1M
Okay, my concerns.
I have an online lpad calculator I am familiar and comfortable using, HOWEVER, what is the actual sensitivity difference in the drivers. Since the tweeter is 5 Ω if i just hooked them up to the same power (voltage) wouldn't the tweeter technically be louder since it's a lower impedance and thus a higher current? so what I'm saying is, yes if they both have 1w of power or however those 2 numbers were measured, then I'm sure their output is 85 and 89 dB but since they're at the same source they're actually receiving different power.. how do I account for this, should i add a 3Ω resistor in series to the tweeter so it has the same seen impedance as the woofer.
if someone takes the time to reply and explain a little, then thank you!
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Actually the opposite happens. When people substitute an original 8 Ohm tweeter by a 4 Ohm the output (SPL) goes down.
Easy to visualize what you mention with curves in a SPICE software.
Easy to visualize what you mention with curves in a SPICE software.
Zlyzen, it's about 6dB difference in sensitivity at heart. So many mixed measurements there that I really don't want to think about it. But the 4.6 ohm TN25 tweeter must be about 91dB converted to 2.83V/1m. 😀
HiVi TN25 Fabric Dome Tweeter 297-408
Paul Carmody's "Overnight Sensations" is set up for freestanding here by the look of it.
https://sites.google.com/site/undefinition/diy-overnightsensations
Slightly different tweeter, I know, but correct ballpark. It's not strictly an L-pad used here, but then there is the effect of the woofer bafflestep coil on reducing sensitivity too. Converting the tweeter filter to second order shouldn't affect things too much either with crossover phase staying roughly aligned with luck, but L and C values will be different.
Dayton Audio ND20FA-6 3/4" Neodymium Dome Tweeter 275-030
HiVi TN25 Fabric Dome Tweeter 297-408
Paul Carmody's "Overnight Sensations" is set up for freestanding here by the look of it.
https://sites.google.com/site/undefinition/diy-overnightsensations
Slightly different tweeter, I know, but correct ballpark. It's not strictly an L-pad used here, but then there is the effect of the woofer bafflestep coil on reducing sensitivity too. Converting the tweeter filter to second order shouldn't affect things too much either with crossover phase staying roughly aligned with luck, but L and C values will be different.
Dayton Audio ND20FA-6 3/4" Neodymium Dome Tweeter 275-030
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As system7 noticed, the tweeter is measured at 1W, 1m. The woofer was measured at 2.83V because that is the 'standard' test voltage... it happens to be the voltage that produces 1W into an 8 ohm resistor.
Amplifiers are normally voltage sources. Get both of these drivers converted to voltage and you're OK to compare. As Steve says, it is likely to be 91dB/2.83V/1m. Don't go adding resistors just over this.
Amplifiers are normally voltage sources. Get both of these drivers converted to voltage and you're OK to compare. As Steve says, it is likely to be 91dB/2.83V/1m. Don't go adding resistors just over this.
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