How To Properly Tune Amps (Calling Spharis)

[Jeff T]

I am gearing up for my stereo install this weekend. I will be taking delivery on Friday (a week later than planned but that is a topic for a different day ). Because of this, I'm on a fairly accelerated timeline for the install because I'm now wasting beautiful summer weekends. Need to knock it out asap.

Anyway, I know there has been some tidbits of discussion around how to properly tune amps using a tone cd and a volt meter (and a good ear ). However, I haven't a clue how to do this. I figured the board could use a good write up on how to do this by folks much smarter than myself. If I feel like it is within our (me and my other installer friends) capability, I may actually give it a shot. With that said, I'm starting at ground ZERO and no nothing about the process.

Anyone want to throw out some steps, equations, etc? TIA.

[spharis]

JL audio has an animated tutorial that covers it fairly thoroughly. Also, the old RF approach is a good starting point if you are going to ear tune. It helps to have 2 people for either method. One on the HU, and one on the amp.

JL
http://mobile.jlaudio.com/support_pages.php?page_id=143

RF
Turn the gains down, put in a track you like, turn off all EQ, loudness, etc. Turn the HU up to about 3/4. Turn the gain up until distortion is heard. Turn it back down a little. Tune the HU but never turn up higher than set above.

[Domsz06]

why do you turn off the loudness?

[philwsailz]

Turn the gains down, put in a track you like, turn off all EQ, loudness, etc. Turn the HU up to about 3/4. Turn the gain up until distortion is heard. Turn it back down a little. Tune the HU but never turn up higher than set above.

Well put, and in a lot fewer words than I would have used!!!!

Agreed, this is best done with two people. When we are in a boat manufacturer's plant, we follow this procedure almost exactly. Our typical attack is to, as you said, use a favorite CD track, (I have a few favorites, with good broad-band frequency spectrum). We will typically open the gains on the amp a little, and then turn up the HU until we notice distortion from the radio. At that point we know where the radio is going to start distorting with most audio material. Then we turn the radio down a little and move to the amp gains. We do exactly as you suggested, turning up the gain until distortion is heard, then turn it down a little.
This way, we have no part of the signal-chain distorting before another, and it typically provides the best S/N ratio.

If there is a subwoofer in a boat, we set that gain last, after setting the high frequency / full range channels. This one is tougher, as distortion is harder to perceive at low frequencies. Many times, depending on the number of subs, their location, and the power available, sometimes it is necessary to turn the full range amp gains down some to provide a satisfactory balance between the subs and the rest of the speakers.

Dom, in my opinion, turning the loudness off is a good idea when setting up, and I agree with SP. Having the loudness setting turned on these days is more often than not a "cheating" way of getting more bass out of the system. If you follow my thoughts above for setting the subwoofer amp gain, you might find that loudness is unnecessary. Leaving it off prevents excessive LF signal from going to your full range amp(s) resulting in higher performance from your full range speakers, without having their cones trying to jump out of their baskets.

[Domsz06]

cool thanks for the info!! that's great!

[lee]

Second that motion.

[chpthril]

Quick ? Once the gaines are set, is it best to leave bass/trebble on the HU alone, or can you use it to fine tune to your listening pleasure?

Great info guys, thanks.

[philwsailz]

Quick ? Once the gaines are set, is it best to leave bass/trebble on the HU alone, or can you use it to fine tune to your listening pleasure?

Great info guys, thanks.

Fine tune to your heart's content! All of us have different ears, and different tastes. Purists will tell you that the best way to sest things is to reproduce the sound ACCURATELY, but let's be honest; what is the ACCURATE sound of a synthesizer or a bass guitar?

Also, realize these controls will help tune your system to correct for speaker placement, weird frequency response of the system, etc. Just be careful; if you find yourself turning bass and treble WAY up or down, that should be a clue to you that the system is wrong, at least to your tastes. For example, if you find that you have to turn the bass setting way up, it could be pointing to an out-of-phase situation, or simply could be pointing to the reality that you need more woofers for your personal listening tastes. If you are turning the treble way up, you might want to consider adding some tweeters. All of the equalization in the world cannot correct for severe speaker problems.

IN GENERAL: it is better to cut than to boost. I.e. if you find that you do not have enough low end, try cutting treble first, rather than boosting bass. If you have mid control, cut that too. It is all relative...

Good luck!

[Domsz06]

i think it's basically all in the listeners ears, as long as no distortion, it's all good

[Razzman]

Well either my ears are shot or i got lucky the first time because after settings gains i have yet to touch the HU adjustments as it sounds so good! I do have to give credit to the RF Powers, they produce some clean sound.

[da.bell]

Razz, I would say you got lucky and the Wakeboarding Gods were looking down on you.

[Domsz06]

wow razz, you must have mad skills!! I'm envious!

[Razzman]

I got lucky is all. I had to get the wife to sit in the boat and listen while i crawled in the hole and adjusted the gain. I'm tone deaf to an extent in both ears, in fact the feds pay me every month for that Of course after i did it she says "i'm not sure if that's right, i really couldn't tell" DOH!

[Domsz06]

ha ha ha, so the truth comes out!

My friends tell me I'm tone death too

[philwsailz]

ha ha ha, so the truth comes out!

My friends tell me I'm tone death too

huh???? What did you say?