Alpine 9815 preout issues

[`pr0digy 10+ year member]

While setting my gains, I decided to check the preouts on my HU. I'm getting only 1.4 volts at +2 bass and 30/35 volume. That's quite a bit lower than the 4 Volts it should be putting out. So I had to set the gains at vol 25, and then the preout voltage was ~ .8 or so. Any ideas what could be causing this ? The HU is just plugged into the stock power/ground, could that be the cause of the lower preout voltage ? Everything else on the HU runs as expected.

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[ANeonRider 10+ year member]

is this the full-range outputs or the sub output? What are you using to measure it? And are u using a tone?

 

[`pr0digy 10+ year member]

is this the full-range outputs or the sub output? What are you using to measure it? And are u using a tone?

Sub output at Sub +2, using a decent DMM, at 50 hz.

 

[nosaj070 10+ year member]

I've come to the conclusion that Alpine's preout voltage levels are extremely inflated. I read a review about a 9815 i believe where they tested them and came up with the same kinda figures that you did. See if you can get by with it, if not get a linedriver.

 

[ANeonRider 10+ year member]

Alpine sub outputs don't output 4 volts unless the sub gain on the deck is at +15.

 

[`pr0digy 10+ year member]

Alpine sub outputs don't output 4 volts unless the sub gain on the deck is at +15.

So should I up the gain on it ? Won't cause clipping, etc ?

 

[squeak9798 5,000+ posts]

So should I up the gain on it ? Won't cause clipping, etc ?

I've heard the same thing as ANeonRider.....the sub level needs to be at +15 to hit it's voltage output.

IMO you should set the sub level to +15 when you set the gains....then you can turn it down if you don't want it as loud, but you can turn it up to 15 and know (well, be reasonably sure since a DMM can't tell you if the signal is clipped or not when you set the gain to begin with) that you're amp won't clip.

 

[`pr0digy 10+ year member]

I've heard the same thing as ANeonRider.....the sub level needs to be at +15 to hit it's voltage output.

IMO you should set the sub level to +15 when you set the gains....then you can turn it down if you don't want it as loud, but you can turn it up to 15 and know (well, be reasonably sure since a DMM can't tell you if the signal is clipped or not when you set the gain to begin with) that you're amp won't clip.

So the level should be at 15, eh ? That won't make the HU distort like a mother or anything ? I was thinking that the sub level was more of a BOOST, not a gain of sorts.

 

[squeak9798 5,000+ posts]

As far as I know, on the Alpines it actually functions more like a volume control (affects all frequencies equally) for the sub out and not like a "bass boost" (peaks a certain frequency and has a certain Q-factor slope associated with it). Correct me if I am wrong, but that's my understanding

 

[ANeonRider 10+ year member]

As far as I know, on the Alpines it actually functions more like a volume control (affects all frequencies equally) for the sub out and not like a "bass boost" (peaks a certain frequency and has a certain Q-factor slope associated with it). Correct me if I am wrong, but that's my understanding

Pretty much the jist of it.

 

[Guijs]

I've heard about that the "+15" setting on the Alpine, actually is the "0" position. So, if you put in the "0" position, it will be in -15dB. I have a 7998 and have the same "problem".

 

[JLCivic 10+ year member]

Alpine had some weak pre out issues on atleast some models over the past few years(the 7897 comes to mind...the testing i read was with the sub out on +15). Apparently, they have fixed that issue for '04 models. So.....your issue may be solved by cranking up the sub out or it may still be under the 4 volts, but that is a good place to start.

 

[00GREENMACHINE 10+ year member]

I always ran my 9813 at +15 and never had any clipping issues.

 

[Redford 10+ year member]

From what I've heard, it'll hit 4v but it'll also be distorted.

 

[`pr0digy 10+ year member]

The +15 fixed the preouts, thanks a bunch guys. I wouldn't have guessed that +15 really meant 0.... Thanks for the help!