Amp clipping since new head unit fitted

Amp clipping since new head unit fitted

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Heaveho

Original Poster:

5,650 posts

181 months

Saturday 15th June
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I recently replaced a 20 year old Alpine head unit with a Sony carplay. This is running through the existing uprated speakers and sub, via a 6 channel Denon amp. I'm experiencing clipping at fairly loud, but not ear splitting volume. The car isn't the quietest thing in the world ( Evo ), so obviously the volume needs to be up a bit more than some other things I own.

I've never experienced this before and wondered if anyone can shed some light on why a change of head unit may have provoked this.

Tenacious

220 posts

6 months

Saturday 15th June
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You sure the impedence match for all speakers to the headunit?

broncoupe

159 posts

233 months

Saturday 15th June
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carry out a full setup on head unit and adjust the amp gains

TEKNOPUG

19,334 posts

212 months

Saturday 15th June
quotequote all
The output voltage on the new HU is probably higher than the old one. Like 1.5v for the hold one and 5v for the new one.

Turn the amp gain all the way down, then turn the HU up until it starts clipping, then back it off a touch. That's you max HU volume. Then turn the amp gain up until it starts clipping, turn back it off a touch.

Alternatively there maybe a low/high output setting on the new HU. Make and models would help.

Heaveho

Original Poster:

5,650 posts

181 months

Saturday 15th June
quotequote all
The new head unit is a Sony XAV1005 DB and the amp is an ancient Denon DCA800. All working fine with the previous equally ancient Alpine TDA-7592R head unit.

TEKNOPUG

19,334 posts

212 months

Sunday 16th June
quotequote all
The Alpine has 2v preout voltage and the Sony has 2.5v. So the Sony is sending a 25% greater voltage output. Also check whether you have loudness or similar switched on. You could also try lowering the volume via the EQ. But first reset the gain on the amp as described above.

Heaveho

Original Poster:

5,650 posts

181 months

Monday 17th June
quotequote all
TEKNOPUG said:
The Alpine has 2v preout voltage and the Sony has 2.5v. So the Sony is sending a 25% greater voltage output. Also check whether you have loudness or similar switched on. You could also try lowering the volume via the EQ. But first reset the gain on the amp as described above.
Thanks for that, I'll start there.

Heaveho

Original Poster:

5,650 posts

181 months

Thursday 20th June
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Just started trying to do something about this. It seems it's a bass related issue, sub specifically. It sounds very clean, right up to the point it starts clipping. I think it's just a matter of there being too much low frequency stuff happening above a certain volume. If I turn the sub down or off, it stops happening regardless of volume level. There's a lot of room for manoeuvre between the settings on the head unit and the amp, so I'm sure I'll be able to reach an acceptable compromise.

Thanks for the help.

MattsCar

1,261 posts

112 months

Friday 28th June
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What subwoofer is it?

DCA800 is a 6x50wrms amp, so most likely only producing 150wrms.

With that output, you will need a very sensitive subwoofer, rated at low power.

Using something with a low sensitivity and say something with 400wrms, will take a fair bit to get it moving, which a 150wrms amp output will struggle to do, before clipping.

Heaveho

Original Poster:

5,650 posts

181 months

Monday 1st July
quotequote all
MattsCar said:
What subwoofer is it?

DCA800 is a 6x50wrms amp, so most likely only producing 150wrms.

With that output, you will need a very sensitive subwoofer, rated at low power.

Using something with a low sensitivity and say something with 400wrms, will take a fair bit to get it moving, which a 150wrms amp output will struggle to do, before clipping.
Hi, it's a Rockford Fosgate, slim depth 12" in a home made enclosure copied from a website. It's been so long since I fitted it I can't remember which particular model it is, and I'm just out of hospital with little mobility, so when I'm better I'll have a gander.

TEKNOPUG

19,334 posts

212 months

Thursday 4th July
quotequote all
MattsCar said:
What subwoofer is it?

DCA800 is a 6x50wrms amp, so most likely only producing 150wrms.

With that output, you will need a very sensitive subwoofer, rated at low power.

Using something with a low sensitivity and say something with 400wrms, will take a fair bit to get it moving, which a 150wrms amp output will struggle to do, before clipping.
The issue is only with the new HU though, so it was working previously. My experience of Denon amps is that their specs are somewhat conservative, so I expect thet are quite a bit more than 50w per channel. Also, the channels can be bridged to 100w x 3. That particular amp has input sensitivity controls that you can adjust to match the HU signal.

A dedicated mono sub amp is always better though.