Gain: Less 'Is' More

NorthQuad · Post by **NorthQuad** » Wed Apr 16, 2008 11:58 am

solacedagony wrote:If it's a sub amp, yea. I'd also say that once you find where it starts to distort, turn it back a bit more than a tad since it's harder to hear distortion in those frequencies.

If it's your front stage amp, I'd say to use well recorded, but loud, music that you know.

Yes, it's for the sub amp. I'll download some higher test tones as well than. Thanks a bunch.

solacedagony · Post by **solacedagony** » Thu Apr 17, 2008 3:42 am

NorthQuad wrote:Yes, it's for the sub amp. I'll download some higher test tones as well than. Thanks a bunch.

50hz is well within the bandpass. I think I would set it with a -3db test tone. You'll never get all your amp has with a 0db testtone because most music probably won't get to that point (unless you listen to a lot of synthetic bass like electronic music). Remember to still do level matching after you set the gains.

Jonathan · Post by **Jonathan** » Thu Apr 17, 2008 9:11 am

It doesn't matter whether you have the speakers connected to the ampliifer or not if you're testing by voltage, which is the reason a voltmeter is recommended. The voltage required to produce peak output is the same regardless of load on the amplifier, current is the variable dependant on impedance.

NorthQuad · Post by **NorthQuad** » Thu Apr 17, 2008 9:44 am

solacedagony wrote:50hz is well within the bandpass. I think I would set it with a -3db test tone. You'll never get all your amp has with a 0db testtone because most music probably won't get to that point (unless you listen to a lot of synthetic bass like electronic music). Remember to still do level matching after you set the gains.

Ok, I was wondering about the difference between a -3db and a 0db test tone. I will remember to do the level matching after I've set the gains. Thanks solace.

NorthQuad · Post by **NorthQuad** » Thu Apr 17, 2008 9:47 am

Jonathan wrote:It doesn't matter whether you have the speakers connected to the ampliifer or not if you're testing by voltage, which is the reason a voltmeter is recommended. The voltage required to produce peak output is the same regardless of load on the amplifier, current is the variable dependant on impedance.

That nearly went over my head. But strangely I understood. Something must be steaming between my ears.

JeremyC · Post by **JeremyC** » Thu Apr 17, 2008 10:10 am

solacedagony wrote:50hz is well within the bandpass. I think I would set it with a -3db test tone.

He could even go as low as -5 db without being able to hear any distortion.

I was goofing around with my 0-scope a few months ago, and tried a -0, -5, and a -10. At -5 I couldn't hear any distortion in my subs but it was slightly noticeable in my mids and tweets. I thought -10 turned out pretty nasty sounding, but most people probably won't notice a difference.

Hey NorthQuad, the difference between a -0 and -3 db test tone is how loud they are. With a 1000 herts -0 db test tone your sending the strongest signal you can threw your amp. So if you set the gain like that you will never clip the input or output. Thats what I use when I'm setting the output on my deck, or the input / output on my DQS.

Now when I'm setting my amps I use a -5 db track. Since the signal isn't as strong as the 0 db, it lets me set the gain just a little bit higher, but keeps the clipping below an audible lvl. It also gives me about 5 db more output than I would have if I set everything to never clip.

If you have some free time download a -0, -5 and -10 db track, and set your gains with all 3. Start with the -0, and listen to some of your favorite music. Go ahead and crank it up, but don't exceed the output you had the deck set to when you adjusted your gains. Now reset your gains using the -5, take another listen. Can you hear any distortion? Now set the gains with the -10. How does it sound to you?

NorthQuad · Post by **NorthQuad** » Thu Apr 17, 2008 12:41 pm

That's a great guild. I'll follow that. Thanks.

Also, I was wondering if Bass Boost should be off and stay off? I've read that it isn't much of a good thing. Do any of you use it?

Another thing was frequency. I have it set at 65hz(i'm sure)for the subs. I listen to every kind of music out there... almost. So is that a good spot? I gave the subs a quick 30 second test with the gain quite low and it rocked the shnikies out of the garage. Sounded so good I may have pooped a little. not really. What level do you like to set yours at?

NorthQuad · Post by **NorthQuad** » Thu Apr 17, 2008 2:41 pm

Another question guys, sorry.

Amps sharing the same ground point on the vehicle. Is this ok?

JeremyC · Post by **JeremyC** » Thu Apr 17, 2008 3:56 pm

My W7 was set at 63 hertz 24 db (the lowest my eclipse would let me), but I was running focal utopia mids so they didn't have a problem filling in.

I will probably rum my morels a little higher, depending on how well they blend with my new mids.

So it really depends on your setup. If the mids and subs blend well at 65 leave it there. If you notice your lacking in your lower mid bass, bring the x-over up to around 80.

Don't worry about all the questions. I like it when people want to learn, and are coming up with good questions.

As for your ground. EVERY piece of my stereo is grounded in the same spot. All 4 amps, processor, CD changer, and my deck. This eliminates the chance of a ground loop forming between 2 components, and giving you some crazy noise.

NorthQuad · Post by **NorthQuad** » Thu Apr 17, 2008 4:44 pm

Perfect. The best spot to ground both amps already has a bolt hole. I sanded the hell out of it but was worried the amps would have to work harder to discharge. I was thinking almost along the same lines as exhaust on a vehicle.

I'll play with the frequency level but I think I like it at 65. Good to know about ground loop. That would apply for all kinds of vehicle electronic installations, eh?

Thanks again, Jeremy.