Hi everyone,
Hoping I can get a bit of help with a little problem I'm having.
I'm trying to set the gains for my subwoofer amplifier using the DMM method. I've done this before with my front stage speakers without any issues.
The amplifier is a 2 channel Class A/B Clarion XR2220 capable (on paper) of producing 190 watts RMS @ 4 ohms when bridged. The subwoofer presents a 4 ohm load, and my head unit is a Kenwood KDC-U556BT with 2.5v preouts. All EQ is flat, no loudness/bass boost/bass extend etc and the subwoofer volume on the HU is at max. I am using a 50Hz sine wave at 0dBfs to try and set the gains and have calculated I'm looking for a voltage of 27.56v.
When I connect the DMM to the amp as usual to set the gains, I attach the probes to the correct terminals for bridged mode and adjust the gain so I see the desired voltage, with the HU volume at 75%. However, with the gains set like this the sub is almost inaudible... like you wouldn't even know the car had a sub in it! The cone barely even vibrates visibly in the boot.
Out of interest, I tried setting the gains with the bass boost on at the amp (I don't want to use it but just wanted to see if it made any difference) and with the gain turned all the way down it reads over 40v.
This doesn't sound right at all, I'm wondering if there is a problem with the multimeter? It was set to 200v AC mode as required.
Right now I have the sub amp gain set by ear with no audible clipping (I am a recording/mix engineer professionally so I do have a good ear for it!) but I would prefer to set it with a DMM to be more accurate.
I bought this subwoofer to replace a no-name cheap underseat 8" woofer rated at 55 watts RMS and, if I go by the DMM reading for gain setting, the old cheap one was about 10 times as powerful as the new one!
Am I missing something here? Any help would be much appreciated!🙂
Hoping I can get a bit of help with a little problem I'm having.
I'm trying to set the gains for my subwoofer amplifier using the DMM method. I've done this before with my front stage speakers without any issues.
The amplifier is a 2 channel Class A/B Clarion XR2220 capable (on paper) of producing 190 watts RMS @ 4 ohms when bridged. The subwoofer presents a 4 ohm load, and my head unit is a Kenwood KDC-U556BT with 2.5v preouts. All EQ is flat, no loudness/bass boost/bass extend etc and the subwoofer volume on the HU is at max. I am using a 50Hz sine wave at 0dBfs to try and set the gains and have calculated I'm looking for a voltage of 27.56v.
When I connect the DMM to the amp as usual to set the gains, I attach the probes to the correct terminals for bridged mode and adjust the gain so I see the desired voltage, with the HU volume at 75%. However, with the gains set like this the sub is almost inaudible... like you wouldn't even know the car had a sub in it! The cone barely even vibrates visibly in the boot.
Out of interest, I tried setting the gains with the bass boost on at the amp (I don't want to use it but just wanted to see if it made any difference) and with the gain turned all the way down it reads over 40v.
This doesn't sound right at all, I'm wondering if there is a problem with the multimeter? It was set to 200v AC mode as required.
Right now I have the sub amp gain set by ear with no audible clipping (I am a recording/mix engineer professionally so I do have a good ear for it!) but I would prefer to set it with a DMM to be more accurate.
I bought this subwoofer to replace a no-name cheap underseat 8" woofer rated at 55 watts RMS and, if I go by the DMM reading for gain setting, the old cheap one was about 10 times as powerful as the new one!
Am I missing something here? Any help would be much appreciated!🙂
My opinion... for what it's worth.
Set it so that you have use of approximately 75% of the volume control's range and so that it sounds like you want it to sound. Then, when driving it hard, listen for distortion or stress (drivers bottoming...) and back off of the volume. Music is too variable to have one 'perfect' setting.
Set it so that you have use of approximately 75% of the volume control's range and so that it sounds like you want it to sound. Then, when driving it hard, listen for distortion or stress (drivers bottoming...) and back off of the volume. Music is too variable to have one 'perfect' setting.
I set my 4-channel amp and monoblock amps up the same way, and came up with the same result (sub sounded weak compared to the door speakers). I don't know if you're experienced with your subwoofer's amp settings, but theres a lot of settings you can mess with to get the sound you want, and possibly more volume...
Did you measure impedance of speakers/subwoofer with your multimeter? The resistance shouldn't vary from what the OEM lists it as, but you can measure resistance from the speaker wire terminals that would be connecting to your amps, and you may get slightly more resistance than listed on the manuals. Dual-coil subwoofers have multiple wiring arrangements which can change their impedance.
How much power are you getting out of your other (assumed 4 channel) amp for the door speakers? It takes more power to produce lower frequencies than highs, so you're probably giving too much power to the coaxials/component speakers, overpowering your low frequencies with mids/highs.
I would back the gain off of the 4-channel amp slightly, rather than increase the sub amp gain any more. I'm pretty new to this, and still figuring this stuff out for myself, good luck!
Did you measure impedance of speakers/subwoofer with your multimeter? The resistance shouldn't vary from what the OEM lists it as, but you can measure resistance from the speaker wire terminals that would be connecting to your amps, and you may get slightly more resistance than listed on the manuals. Dual-coil subwoofers have multiple wiring arrangements which can change their impedance.
How much power are you getting out of your other (assumed 4 channel) amp for the door speakers? It takes more power to produce lower frequencies than highs, so you're probably giving too much power to the coaxials/component speakers, overpowering your low frequencies with mids/highs.
I would back the gain off of the 4-channel amp slightly, rather than increase the sub amp gain any more. I'm pretty new to this, and still figuring this stuff out for myself, good luck!
You need to have the sub connected to load the amp properly and keep the voltage output more stable, are you setting gain with it disconnected? Really a dmm would only be useful for trying to match gains from one channel to another when setting preliminary gain levels. Otherwise you would be getting an estimated average of ac voltage and an idea of wattage if you knew the actual impedance of the woofer while it was playing at that exact frequency and if it were in the exact enclosure volume used to determine its characteristics. There are a lot of variables that determine what voltage you will be seeing at the amplifier terminals. The way Perry mentioned is the most efficient all around way to do it, there are many factors that can change sub performance from one vehicle, head unit, amp, crossover setting, enclosure, etc to the next.
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Thanks for the info. Most sources I found online recommended isolating the amplifer from the speakers for this exercise.
I'll leave the speaker(s) connected to the amp when measuring AC voltage, I'll give it a shot and see what the difference in reading is. I'm using a fluke process meter so I'm sure the readings are reliable.
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