gains. surprised by setting

sonso_chi · Post by **sonso_chi** » Fri May 05, 2006 12:55 am

Okay, I recently installed a new system.
http://www.caraudiocentral.net/forums/s ... php?t=4306

Regarding my gain, I am shocked by how high I have to set it. My 2 subs' thermal rms rating is 600w. My amp is 1500w @ 2 ohms (1632w on birth sheet). So, the amp puts out more wattage than the speakers are ideally designed for. This would have me think that I need to have the gain at a relatively lower setting. Also, the acceptable signal voltage range of the amp is up to 5 volts. Well, my Premier deck puts out 6 volts! Again, leading me to believe that the gain would need to be set relatively low (doubly).

All the wiring is perfect, and the subs sound pretty good so far (I have only listened to a limited amount of music, plus they are not likely broken in yet). I've ran them at a good volume for about 1 and a half hours.

But, I have the gains set at about 95% of the maximal setting. That is how high I have to set them to have the speakers get loud. This is even with the deck set to maximal subwoofer "volume" and the regular volume set high.

This may not even be an issue or something to respond to, but again, I would have expected to have to set the gain low versus almost to it's max position. This is without me using the remote base control (bass boost that connects with the telephone-like jack), but still, I wouldn't think I would need to use the bass boost.

When I do have the gains up though, the subs get loud and I am certain that the amp is putting out the watts.

phthisis · Post by **phthisis** » Fri May 05, 2006 1:05 am

Use a DMM to set the gain. The output from the HU is not gonna be its rms voltage. It likely to be a value that is seen when perfect conditions are met and there is something like a 1khz tone playing.

Robert Wollenberg · Post by **Robert Wollenberg** » Fri May 05, 2006 1:39 am

Yeah, if your deck puts out 6 vrms and you have your gains turned up 95%, I'm quite sure you're clipping the hell out of that amp. Are you sure you have your subs wired right?

Your amp puts out 1632 wrms at what impedence? How many subs are you running? Single or dual voice coils? How do you have them wired?

Bwcad1 · Post by **Bwcad1** » Fri May 05, 2006 4:15 am

what number is your gain pointing at? i think you have it confused. the .2 means your gain is turned down and the higher number means your gain is turned up.

_gonz_ · Post by **_gonz_** » Fri May 05, 2006 4:28 am

Pioneer outputs.

If you measure them, you might be surprised to find only 2v.
That would quite adequately explain your gain settings.

Robert Wollenberg · Post by **Robert Wollenberg** » Fri May 05, 2006 4:35 am

I remember that from back when I sold pioneer. 6vrms means six volts divided by the three channels. Front, Rear and Sub. 2vrms each.

Bwcad1 · Post by **Bwcad1** » Fri May 05, 2006 4:41 am

my pioneer 8400mp is 4v rated and does anywhere from 2.2-3.7 per and i belive you have the 8mp which has 6v preouts and ive seen that go from 2.5-5.2.

_gonz_ · Post by **_gonz_** » Fri May 05, 2006 4:52 am

Another possibility...

Rockford, now being so mainstream, could realize the BestBuy installers crank the gains. How many times have we heard this? So perhaps RF has designed the amp's sensitivity to be so low... that you need the gain maxxed out. Under the assumption that, 95% of end users are going to maxx them out regardless.

It makes sense if you think about it.
Especially since 95% of the headunits on the market, all operate with a relatively standard output range.

Of course, it could be unintentional, sort of a defect, perhaps the rail voltage is just set too low.... and the gains compensate for that. Either way, it's the same story, just a question whether it's done by design, or not properly tuned by mistake.

If you wanted to have the amp "checked out" and tuned/beefed up... I know of a skilled Russian guy who is an engineer at Kicker. He does side jobs on amps for reasonable prices. Kinda worth paying a tech to calibrate your amp... and definitely beats trying to get an ebay dealer to replace it. Just a thought.

Robert Wollenberg · Post by **Robert Wollenberg** » Fri May 05, 2006 4:54 am

I never measured mine. I'm curious. I've got the 940MP. I'll have to measure that when I get home.

_gonz_ · Post by **_gonz_** » Fri May 05, 2006 5:06 am

Just bear in mind that the output voltage changes, increases and decreases, with the volume level as it increases and decreases. In other words, output voltage is not a fixed value.

Figured I'd toss that out there, just in case anyone reading did'nt realize it.