Disappointing Sub Output... Any Ideas?
Thread Starter
Pro
Joined: Dec 2010
Posts: 529
Likes: 11
From: Troutman NC
Disappointing Sub Output... Any Ideas?
I bought a used 07 C6 that came with a bunch of aftermarket audio toys. The sub is hooked up to a McIntosh MC443M (apparently a high end amp... back in its day, I guess its pretty old now). Here are the specs...
1 channel X 300w into 4 ohms or 500w into 2 ohms. Power guard. MOSFET PWM power supply. Multi-stage thermal protection. Ported tunnel forced-air cooling. Continuously variable low pass filter with 24dB/octave slope. Separate high pass filter with 18dB/octave slope. Input level control.
The sub is just a 10" Kenwood. I know very little when it comes to specs, but from what I've read it seems this amp should be driving this sub pretty hard, but its barely moving.
1 channel X 300w into 4 ohms or 500w into 2 ohms. Power guard. MOSFET PWM power supply. Multi-stage thermal protection. Ported tunnel forced-air cooling. Continuously variable low pass filter with 24dB/octave slope. Separate high pass filter with 18dB/octave slope. Input level control.
The sub is just a 10" Kenwood. I know very little when it comes to specs, but from what I've read it seems this amp should be driving this sub pretty hard, but its barely moving.
Tech Contributor
Joined: May 2003
Posts: 7,035
Likes: 134
From: North Augusta, SC
turn up gain/level control **** (just like a volume control)
adjust filters properly (LPF set around 100hz, HPF around 30hz, if a switch makes you choose set it to LPF)
what is signal source? is it giving the sub a good signal?
what are specs on sub? is it wired for 2 or 4 ohms?
if everything else is OK, swap polarity of sub (0/180 phase switch or just switch wires)
adjust filters properly (LPF set around 100hz, HPF around 30hz, if a switch makes you choose set it to LPF)
what is signal source? is it giving the sub a good signal?
what are specs on sub? is it wired for 2 or 4 ohms?
if everything else is OK, swap polarity of sub (0/180 phase switch or just switch wires)
Safety Car
Joined: Jan 2007
Posts: 4,295
Likes: 8
From: Issaquah WA
As Mark mentioned, check the source unit. Often there are subwoofer output controls on the deck, and the settings for the sub can easily be misadjusted. The gain controls on the amp are less likely to be accidentally turned, so I would check the deck first.
Thread Starter
Pro
Joined: Dec 2010
Posts: 529
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From: Troutman NC
Good stuff, thanks! Twisted a few ***** and its now much stronger. I pulled the sub out and the box was stuffed with pillow foam... is this typical? The overall install of the whole system is definitely half assed.
Melting Slicks
Joined: Oct 2003
Posts: 2,834
Likes: 91
From: California
I don't have much time right now, but if you google it you'll get so many hits you could read for a month about it.
Also, you may want to look up how to use a digital multi-meter to tune/adjust your amplifier using test tones. Just dialing up the gain can cause issues if you go too far, which can be easy to do with a subwoofer.
Thread Starter
Pro
Joined: Dec 2010
Posts: 529
Likes: 11
From: Troutman NC
Since I'm digging deeper into this and actually trying to understand what I'm doing, here are my configuration options. I was expecting something to actually say "gain," "LPF" and "HPF." What should I actually be adjusting here?
The sub is a Kenwood KFC-1200F and is actually 12". No idea what its wired for, I'm assuming 4 ohm since there aren't any options on the sub itself, and its a single voice coil at 4 ohm.
The sub is a Kenwood KFC-1200F and is actually 12". No idea what its wired for, I'm assuming 4 ohm since there aren't any options on the sub itself, and its a single voice coil at 4 ohm.
Tech Contributor
Joined: May 2003
Posts: 7,035
Likes: 134
From: North Augusta, SC
Find a 50hz test tone to download on the net. Turn the 'level' **** on amp down all the way, turn HU volume to 75% or so and play the 50hz tone. Turn up level **** until sub clips (instead of a smooth rumble you'll hear an obvious buzz-like sound), turn level down just enough to stop clipping. That would be the max level for the sub, remember where it is. Turn level back down and play some music, adjust level up until sub blends well with fronts, don't exceed max level you just determined. That will prevent any damage to sub.
For other *****, I'd put 'sub filter' in. Sub freq looks ok. The 1/1&2/1-4 switch depends on how many RCA's are connected. If there are 2 cords plugged in, leave it at 1&2.
Polyfill can have a big affect on sub sound, try it both ways to see which you like better.
For other *****, I'd put 'sub filter' in. Sub freq looks ok. The 1/1&2/1-4 switch depends on how many RCA's are connected. If there are 2 cords plugged in, leave it at 1&2.
Polyfill can have a big affect on sub sound, try it both ways to see which you like better.
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