another alpine 9815 question /brahma/amp

[wolfey 10+ year member]

I just got one of these decks and installed it in my new 2003 corolla. I have, to go with it, a brahma 12" in a 1.9 cf enclosure tuned to 38 hz, and powered by a revolution 1500d or whatever its called. (The revo-adire amp)..

Anyways, i've had the brahma hooked up in my escort before in a sealed box and it got pretty dang loud.. now i have it in a ported enclosure that is tuned pretty high (so it should be loud) and it just doesnt seem very loud.. At first i was having trouble with my ground connection and something weird was happening where when i first checked the voltage it said like 12.5 volts or so ( i wasnt sure if the ground was good).. then when i went to play it i got no sound.. and i looked at the amp and it was in protect mode.. i checked the voltage again and it was at 3.5 volts then.. this was in a matter of a minute or so, it wasnt like i drained my battery.

That was late last night.. this morning i had the same problem.. since then, after i got off work i've been messing with it.. I moved the ground to another location on the opposite side but, but in the exact same type of location.. It is on a bolt that attaches to a brace on the seat, the brace looks to attach to the chasis..

Now it seems to always play, does not go into protect, and displays proper voltage with a voltmeter. However, it seems my sub is much quieter than the rest of the music. I had to set the gains way up and put the sub out setting wayyy up also just to get it to go with the music.. I have the gain past the 1/2 mark (with 4 volt preouts???) Also, i am running the sub at 4 ohms though so i dont blow it.. It is decently loud but i expected much more.. Could the ground still be bad even though its registering 12.5 volts and 14 or so when its on?? what else could be the problem? i've been playing all day with configuring the crossovers and equilizer on that thing and **** is it confusing to operate. could it maybe just be i need to set the crossover down several decibals for the front speakers since maybe they have a higher sensitivity and thats why they are playing louder..?

btw, it is wired properly, i had it hooked up in my bedroom to an amp that put out about 90 watts and it seemed louder there than in my car.. I checked with the multimeter and its showing about 3.2 ohms resistance which seems a bit low but as i recall thats pretty typical for brahma coils in parallel. Any suggestions?

Click to read more...

 

[wolfey 10+ year member]

ok maybe thats just too long for everybody to read..

Forget about all that unless you think there definitely is a problem with the ground.

To all those people who have 9815's, how high do you have to set your sub out to mix with your system? Also, do you have to lower the active crossover to your fronts and mids to get it to mix (i lowered mine to -6 on the fronts and -7 on the rear) set the gain on my revo to about 1/2, and the sub out to at least 10 of 15, and now it seems to mix pretty well. Like i said i have a b12 in a 1.9cf box and the revo running at 4 ohms (it says ~3.2 ohms with the DMM, its in series. This is in a corolla (small car).. It seems to get pretty loud now, i was expecting a bit better though. btw the deck is powering the stock speakers.. and seems to do quite well.

with my JVC i had before (kdsh-99) i used to have the gain at about 1/4 and sub out at about 5 out of 12 and it was pretty loud by then already. But my setup in that car was quite different though cus i had another woofer also (infinity perfect) and they both were in a sealed box, the brahma was at 4 ohms and the perfect at 4 in parallel together..

ALso, should the gain setting be changed depending on the impedance of the driver??

if anyone could give me some info on setting the gains, possible problems, or especially tips on the 9815 and how you have the crossover set, i would greatly appreciate it.. Sorry for the long posts

 

[Tungsten 10+ year member]

My 9815 reacted the same way with my MTX 6500D amp and twin Alpine SWR-1021D subs. I ended up moving the gains to about 75% of maximum on the MTX amp and bumped the Alpine's subwoofer volume (punch the knob a few times til you get to the sub setting) up to about 10. This seems to be the midway point for the sub volume.

Now it rattles the car fairly easily. //content.invisioncic.com/y282845/emoticons/smile.gif.1ebc41e1811405b213edfc4622c41e27.gif

My suggestion is just to experiment with the various EQ, crossover and subwoofer volume settings until you get something you like. The 9815 is obviously geared more toward the sound quality afficianado moreso than the SPL fiend. You have to work with it a bit to get it to be "loud"

Hope that helps.

 

[Tungsten 10+ year member]

BTW, I have my crossovers set as follows:

Front: 80Hz cutoff with 0dB "boost" and 12dB crossover roll-off

Rear: nonexistant - no rear speakers

Low: 100Hz cutoff with 0db "boost" and 12dB crossover roll-off

 

[wolfey 10+ year member]

ok that sounds cool to me then.. I think everything is ok now.. the amp is getting pleanty of voltage and the subs mix well with the music, and i'm able to play it loud.. before the speakers were distorting by the time the sub was noticeable. I have it set to 125 hz at the front and rear with a 12 db slope and -5db up front and -7db in the rear.. This helps because i think the speakers are a lot more efficient than the sub is. The sub out is at 10-15 depending on the song and my tastes.. and the gain is set to about 1/2. Seems good so far... i might play around with another ground location to see if anything changes but i highly doubt it. You might try lowering the gain on your amp and setting the crossover to your frontstage lower and see if you like it better, i did anyways.

Also, how do you have the MX thing set for playing cd's or mp3's? just curious, i have mine on and set to 1 i believe.. it seems to sure add a lot of impact to the sound, mostly bass though.. It helps but it doesnt seem quite right, almost like a bass boost but a little better.. without it on though the bass just isnt there..

 

[JLCivic 10+ year member]

Originally posted by Tungsten My 9815 reacted the same way with my MTX 6500D amp and twin Alpine SWR-1021D subs. I ended up moving the gains to about 75% of maximum on the MTX amp and bumped the Alpine's subwoofer volume (punch the knob a few times til you get to the sub setting) up to about 10. This seems to be the midway point for the sub volume.

 

Now it rattles the car fairly easily. //content.invisioncic.com/y282845/emoticons/smile.gif.1ebc41e1811405b213edfc4622c41e27.gif

 

My suggestion is just to experiment with the various EQ, crossover and subwoofer volume settings until you get something you like. The 9815 is obviously geared more toward the sound quality afficianado moreso than the SPL fiend. You have to work with it a bit to get it to be "loud"

 

Hope that helps.

That sounds like a nice way of saying the sub pre out may be a little weak. Very nice pre outs would help with any deck geared toward sq. A guy on another forum tested his 7897. These were his results.

the front/rear pre outs clipped at 32 out of 35(they did much better than the alpine that the local shop tested)

at 31(1 click below clipping), they did 3.9 volts

The sub out never clipped, but at full volume(and bass cranked on the deck), it did 3.5 volts.

Now, the issue was at volume 31(max volume without clipping on the front/rear pre outs), the sub pre out voltage was 1.7 volts.

That last part of his testing may account for the numerous posts I have seen on many forums complaining of a lack of bass with the newer alpines.

I just thought his test was worth mentioning. Your sub pre out may just be low. I doubt the pre outs on the 9815 are any different.

 

[Tungsten 10+ year member]

Originally posted by JLCivic I just thought his test was worth mentioning. Your sub pre out may just be low. I doubt the pre outs on the 9815 are any different.

I am 99% sure you are correct, I just haven't had a chance to pull an o-scope out from the lab at work and put them on the sub pre-outs to confirm it. I may do that this week to see what the signal strength really looks like.

 

[JLCivic 10+ year member]

Originally posted by Tungsten I am 99% sure you are correct, I just haven't had a chance to pull an o-scope out from the lab at work and put them on the sub pre-outs to confirm it. I may do that this week to see what the signal strength really looks like.

Yeah, the guy on the other forum(it was elitecaraudio) used an O-scope. The local shop tested the pre outs on a 7998(could have been a 7897) using a powered speaker and some test tones(very quick way to check pre outs), and the alpine clipped earlier than it did in this guy's test.

 

[Tungsten 10+ year member]

Well... I did the test today and the scope showed a pre-out voltage of 1.9 volts (approx. considering fudge factor of actually reading the scope, etc.) with the volume set at 31 on the Alpine head unit.

Not quite what I would have hoped for. //content.invisioncic.com/y282845/emoticons/rolleyes.gif.c1fef805e9d1464d377451cd5bc18bfb.gif