Hi there,
I have a Jamo D8 sub, part of of the D8 concert 5.1 set.
The problem is, I can not set the volume over 25% on this amplified sub because otherwise it overload. I though at first that it was because the previous owner had to change the foam (edited: not diaphragm), but after checking, it looks like it was well done.
The thing is, this sub is advertised as a 400w class D amplified sub. a class D amplifier is supposed to be 90% efficient so I would suppose that it can ouptut something like 300wrms.
After unmounting the speaker, I've checked the reference, JAMO 20389, to replace it but this speaker appears to be only 90wrms, so I guess that i's normal that it get constantly overloaded, even if there is a passive radiator next to it, what do you think? (I asked Jamo and they confirm this speaker is genuine in the D8 SUB)
Next, I was thinking to buy another more powerful speaker to replace it, given it's a 4ohms, my choice narrowed to car speakers but I hardly find any speaker that match the 98db of the previous jamo speaker, do you think that matters?
Thanks, Jay.
I have a Jamo D8 sub, part of of the D8 concert 5.1 set.
The problem is, I can not set the volume over 25% on this amplified sub because otherwise it overload. I though at first that it was because the previous owner had to change the foam (edited: not diaphragm), but after checking, it looks like it was well done.
The thing is, this sub is advertised as a 400w class D amplified sub. a class D amplifier is supposed to be 90% efficient so I would suppose that it can ouptut something like 300wrms.
After unmounting the speaker, I've checked the reference, JAMO 20389, to replace it but this speaker appears to be only 90wrms, so I guess that i's normal that it get constantly overloaded, even if there is a passive radiator next to it, what do you think? (I asked Jamo and they confirm this speaker is genuine in the D8 SUB)
Next, I was thinking to buy another more powerful speaker to replace it, given it's a 4ohms, my choice narrowed to car speakers but I hardly find any speaker that match the 98db of the previous jamo speaker, do you think that matters?
Thanks, Jay.
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I'm not sure I follow - did the previous owner replace the driver in the subwoofer, did he re-cone it, or is that the original driver in the subwoofer?
It probably isn't uncommon for a subwoofer driver to have a lower RMS rating than the amplifier driving it in an amplified subwoofer. After all, unless you plan to listen to sine waves at top volume at the system's lowest impedance, that driver is not going to see 400W continously. If anything, your issue might be an excursion-related one, not a power-related one.
And I doubt that the subwoofer driver is 98dB/2.83V, unless it has a very low impedance.
It probably isn't uncommon for a subwoofer driver to have a lower RMS rating than the amplifier driving it in an amplified subwoofer. After all, unless you plan to listen to sine waves at top volume at the system's lowest impedance, that driver is not going to see 400W continously. If anything, your issue might be an excursion-related one, not a power-related one.
And I doubt that the subwoofer driver is 98dB/2.83V, unless it has a very low impedance.
Thanks Brian.
The original driver is currently in the subwoofer.
Sorry, my mistake, the previous owner has only replaced the foam.
I understand that the driver is not going to see 400w continously but I'm surprised that a 90wrms driver is in an advertised 400w subwoofer sold at msrp $2590.
I actually can't turn the subwoofer power over 25% or it get overloaded.
I really was going to buy a genuine Jamo driver replacement, but at $250 for a 90wrms I think it's a bit overpriced and I'm not even sure that it will solve the problem.
As per the driver specs, here is what I found:
90 watt RMS
180 watt musical
FS: 39 Hz
Qms: 5.00
Qes: 0.30
Qts: 0.290
Vas: 104.0 l
Spl: 98.1 dB
Impedance: 4 ohm
Swing: 25 mm
Frequency range: 50 - 5000 Hz
The original driver is currently in the subwoofer.
Sorry, my mistake, the previous owner has only replaced the foam.
I understand that the driver is not going to see 400w continously but I'm surprised that a 90wrms driver is in an advertised 400w subwoofer sold at msrp $2590.
I actually can't turn the subwoofer power over 25% or it get overloaded.
I really was going to buy a genuine Jamo driver replacement, but at $250 for a 90wrms I think it's a bit overpriced and I'm not even sure that it will solve the problem.
As per the driver specs, here is what I found:
90 watt RMS
180 watt musical
FS: 39 Hz
Qms: 5.00
Qes: 0.30
Qts: 0.290
Vas: 104.0 l
Spl: 98.1 dB
Impedance: 4 ohm
Swing: 25 mm
Frequency range: 50 - 5000 Hz
Interesting - those published specs do add up to a 98dB/2.83V driver. Not really a subwoofer driver though, unless used in an "extended bass shelf" alignment. Still, if the Xmax of that driver is actually 12.5 mm (25 /2) and assuming a 2. cu.ft. box tuned to 39 Hz, it should not be running out of excursion within its passband with only 400W on tap. If its being hit with signals BELOW its passband however, that's another matter. What are you trying to play back on it that's leading to distortion?
Trouble setting the volume control to "11"? (That's a famous joke from a movie.)
Does the sub system seem to play louder than you'd ever want it to, regardless of where the volume control is pointing? If so, you don't have a problem.
How the pieces work together and where the volume control points to are called "gain management". That relates to the amplification factor but not to the maximum power capability, unless somewhere along the line you don't have enough amplification to reach full power at the final output. So long as you aren't bumping the top of your volume control in order to get the loudness you'd like, you have no problem.
Don't forget, a sub with a low crossover point doesn't make a lot of sound except on low bass music. Conversely, testing a sub with big 30 Hz sine waves may be a whole less audible than you imagine.
Or do i misunderstand your question?
B.
Does the sub system seem to play louder than you'd ever want it to, regardless of where the volume control is pointing? If so, you don't have a problem.
How the pieces work together and where the volume control points to are called "gain management". That relates to the amplification factor but not to the maximum power capability, unless somewhere along the line you don't have enough amplification to reach full power at the final output. So long as you aren't bumping the top of your volume control in order to get the loudness you'd like, you have no problem.
Don't forget, a sub with a low crossover point doesn't make a lot of sound except on low bass music. Conversely, testing a sub with big 30 Hz sine waves may be a whole less audible than you imagine.
Or do i misunderstand your question?
B.
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@Brian: If I understand what you say, this driver model is well fitted for this subwoofer. That make a lot of sense considering that the serie D8 was well received back then. Thanks a lot for your help and your knowledge, I will probably try to change the foam again or replace the driver by a new one of the same model.
BTW I use the subwoofer for both music and movies and both lead to distorsion.
@Bentoronto: Thanks, actually the subwoofer is not loud enough. it would be great if I could set it to 40-50% power, but over 25% it leads to distorsion, just like when speaker couldn't handle the power it receives.
BTW I use the subwoofer for both music and movies and both lead to distorsion.
@Bentoronto: Thanks, actually the subwoofer is not loud enough. it would be great if I could set it to 40-50% power, but over 25% it leads to distorsion, just like when speaker couldn't handle the power it receives.
Hi everyone, an update because the problem is solved.
I trusted the original room calibration of my onkyo receiver and the level of the sub was set to +12db, thus the signal received by the sub amp was too high.
My bad. Again, thanks for your help, Brian and Bentoronto.
I trusted the original room calibration of my onkyo receiver and the level of the sub was set to +12db, thus the signal received by the sub amp was too high.
My bad. Again, thanks for your help, Brian and Bentoronto.
If amplifier is rated 400Watts, it means output power not the mains input.
Having around 90% efficiency, it is pulling something like 450-500Watts from the wall socket at full rms power. In reality its never going to be that much tho, because of crest factors etc..
Having around 90% efficiency, it is pulling something like 450-500Watts from the wall socket at full rms power. In reality its never going to be that much tho, because of crest factors etc..
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