Auto Tuba for Accord Coupe

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Bill Fitzmaurice
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Joined: Tue May 02, 2006 5:59 pm

Re: Auto Tuba for Accord Coupe

#61 Post by Bill Fitzmaurice »

MA043HA wrote:I had it pretty loud but not maxed out at one point and loudly said "Hey Siri" just to see if she would activate that way instead of touchscreen. Must have been an odd coincidence but as soon as I said that the sound got much quieter and very distorted.
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I don't believe in coincidence, though I can't say what could have caused it.

MA043HA
Posts: 60
Joined: Mon Jul 11, 2016 11:17 am
Location: Mass

Re: Auto Tuba for Accord Coupe

#62 Post by MA043HA »

Thanks Bill. In case I haven't mentioned it already the AT was running off one channel of the Focal 6.900 (http://www.focal-america.com/wp-content ... Manual.pdf). So it was getting up to 150 watts RMS into the 4 ohm driver.

MA043HA
Posts: 60
Joined: Mon Jul 11, 2016 11:17 am
Location: Mass

Re: Auto Tuba for Accord Coupe

#63 Post by MA043HA »

The new amp was installed and configured by Matt last Wednesday so I've had a few days to play with it. It's setup the same way as before with 4 channels biamping the component set through the Focal passive xover and the AT on one channel leaving one channel free. The amp is highpassing the AT at about 37Hz 12db/octave and lowpassing it about 120Hz 12db/octave. The slope isn't adjustable but could be if I started using the HU to set xover which it is not doing at all now.

When I asked Matt what he thought had blown the amp he said he didn't know but the only thing not fully known to him is the AT. He later offered that I "try" one of his small ready-made JL Audio ported subs but I told him I was pretty attached to making the AT work at its best.

The system sounds good now - very "clear" is how my guest listeners describe it and I concur. All the instrumental lines I was missing with the OEM system are back. The AT with the "sub knob" in the middle range sounds good on most music lending a nice fullness and punch to the bass. It's easy to turn it up too much not in terms of loudness but to the point where the bass gets localized in the rear of the car.

Loudness (volume range) is down compared to Matt's original settings. He says the Kenwood HU begins to distort about "32-35" on its volume scale. At "30" it's loud but not really so much. I wouldn't want it any less at 70 mph. I suspect he turned down the gain overall hoping not to blow another amp.

This seems like a good place to wind down my "build" thread as now it's all about the tuning. Thanks to all for advice and encouragement :)

CoronaOperator
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Joined: Wed Mar 25, 2009 7:07 pm
Location: Medicine Hat, Alberta, Canada

Re: Auto Tuba for Accord Coupe

#64 Post by CoronaOperator »

MA043HA wrote:lowpassing it about 120Hz 12db/octave .... to the point where the bass gets localized in the rear of the car...The slope isn't adjustable but could be if I started using the HU to set xover which it is not doing at all now.


That x-over point seems too high. If you look at the autotuba graph, it gets really efficient from ~90hz and up. That would be the source of your localisation. If you could increase the slope to 24db/octave it would help you out as well as lowering the subwoofer crossover point to around 70hz or so. You can leave your high pass crossover where it is. There won't be any "hole" by leaving a gap in the crossover range as x-overs are a slope and not a cliff, there will still be plenty of 70-120hz bass coming through.
MA043HA wrote:He says the Kenwood HU begins to distort about "32-35" on its volume scale."
That's pretty normal, my JVC does the same at 35/50

MA043HA wrote: I suspect he turned down the gain overall hoping not to blow another amp.
I'm not sure what fried your first amp but that is no reason to turn the gains lower than they should be. Even cheap amplifiers have built in protection circuitry, any amp that cant handle full load belongs in the trash can.
Built:
17" width 10" driver Autotuba
2 x 29" width dual Lab12 Tuba60
6 x DR250 2510/asd1001
In progress:
2 x DR250 2510/asd1001
For best results, point the loud end of the array towards the audience

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