Correct way to set gain with DMM?

[JuicyJeff 10+ year member]

That doesn't state what to do with the lpf. Do you keep that down. Then turn it up after you fins your max gain or set the lpf first and then find voltage

 

[VWBobby 10+ year member]

Haters gonna hate

STFU. You want to give advice and don't even have a system. The advice you give is bogus and tell people they don't need a DMM, GTFO.

To answer the OP's question:

If you set your amps to a 0 DB test tone, your system is generally too quiet for normal operation. I recommend a -2 or -3db test tone.

Measure your voltage on the AC setting of your DMM. If you play a 50hz test tone and get lets say ~2V on your RCA's at the amp, set your gain to around 2V if your amp is marked by voltage on the gain settings.

If you have an amp that is more RMS than your subs can handle, you need to set your gains to the FINAL POWER coming out of the amp speaker terminals. There are charts online for Volts - Watts conversion @ various ohm loads. This way you don't blow your subs setting the gain to the head unit power.

Setting your mids/highs is the same method, just use tones that fall in the same range as each gain you are tuning (if active).

 

[Heeltoeclutch 10+ year member]

If you set your amps to a 0 DB test tone, your system is generally too quiet for normal operation. I recommend a -2 or -3db test tone.Measure your voltage on the AC setting of your DMM. If you play a 50hz test tone and get lets say ~2V on your RCA's at the amp, set your gain to around 2V if your amp is marked by voltage on the gain settings.

If you have an amp that is more RMS than your subs can handle, you need to set your gains to the FINAL POWER coming out of the amp speaker terminals. There are charts online for Volts - Watts conversion @ various ohm loads. This way you don't blow your subs setting the gain to the head unit power.

Setting your mids/highs is the same method, just use tones that fall in the same range as each gain you are tuning (if active).

Thanks bobby. I'm looking for those charts now - only finding equations and irrelevant calculators... Wouldn't you need to know current to convert volts to watts? and would this just be the current as measured across the power and ground terminals on the amp?

If you know of a location or have any idea of where to find these charts i'd be most appreciative //content.invisioncic.com/y282845/emoticons/smile.gif.1ebc41e1811405b213edfc4622c41e27.gif

 

[THATpurpleKUSH 5,000+ posts]

You mean this chart?

http://i76.photobucket.com/albums/j23/steveo200077/RMSchart.jpg

I did this with my headunit on about 95% volume cuz my door speakers dont distort till full volume. I used a 0db 50hz test tone. Music is a little less than when I had it set by ear, but if I take it to a competition I'll be safe playing a test tone.

Oh and my subs were connected while doing this. I would advise using hearing protection while doing this.

And my amp has a birthsheet of 1400rms at 1 ohm so I set it a little conservative with 1300x1 or 36v

 

[-01limited- 10+ year member]

That doesn't state what to do with the lpf. Do you keep that down. Then turn it up after you fins your max gain or set the lpf first and then find voltage

I set my lpf ~100 hz, but this is just to set what frequencies to send to your subs. You wouldnt want to have it down though and set your gain bc your amp wouldnt be sending out that 50 hz tone that you're using to set it with so it would be quite pointless.

 

[-01limited- 10+ year member]

Haters gonna hate

Naw, I just speak the truth.

and you saying that just screams you know this man.

 

[09civic 5,000+ posts]

STFU. You want to give advice and don't even have a system. The advice you give is bogus and tell people they don't need a DMM, GTFO.
To answer the OP's question:

If you set your amps to a 0 DB test tone, your system is generally too quiet for normal operation. I recommend a -2 or -3db test tone.

Measure your voltage on the AC setting of your DMM. If you play a 50hz test tone and get lets say ~2V on your RCA's at the amp, set your gain to around 2V if your amp is marked by voltage on the gain settings.

If you have an amp that is more RMS than your subs can handle, you need to set your gains to the FINAL POWER coming out of the amp speaker terminals. There are charts online for Volts - Watts conversion @ various ohm loads. This way you don't blow your subs setting the gain to the head unit power.

Setting your mids/highs is the same method, just use tones that fall in the same range as each gain you are tuning (if active).

Why does everything think you have to have a setup in order to know things? And you dont need a DMM to properly set your gains

 

---------- Post added at 03:44 PM ---------- Previous post was at 03:43 PM ----------

 

Naw, I just speak the truth.
and you saying that just screams you know this man.

No, im just sick of arguing with you

 

[-01limited- 10+ year member]

Why does everything think you have to have a setup in order to know things? And you dont need a DMM to properly set your gains 

---------- Post added at 03:44 PM ---------- Previous post was at 03:43 PM ----------

 

No, im just sick of arguing with you

bc no matter what you do to make sure you're getting the most out of your amp and not clipping using a dmm/oscope IS the only way to properly setting them. Yeah you can do it by ear, but its no where near as accurate. But go ahead, lets hear you argue this because I forgot you've set up so many systems and been around em' so long that you can just hear the sweet spot. I bet we could line up amps and have you set them "by ear" and then go back and check your settings with an oscope and you'd either be clippin the fuck of the signal or just not getting your amps potential.

Just stop, this thread is about setting your gains with a dmm and nothing else. Read the title little boy.

 

[Heeltoeclutch 10+ year member]

Thanks for all the help guys. I just went out to my car and I can't set it to 3/4 full volume because my speakers start to puke at a little over half, even with 125 Hz HPF (stock front speakers rated at 40W, running 102ish watts to each). I never listen past like 14 out of 40 though; 15 will make your hearing fuzzy for a while //content.invisioncic.com/y282845/emoticons/tongue.gif.6130eb82179565f6db8d26d6001dcd24.gif They sound awesome at the volume I listen at.

So I put it at 20 and took measurements; with gain at 1/3ish voltage was 2.67 out of the bridged terminals. I tried measuring amps across the power terminals and then realized you have to measure with the meter in series //content.invisioncic.com/y282845/emoticons/laugh.gif.48439b2acf2cfca21620f01e7f77d1e4.gif I tried hooking up the E8 to get an idea of the output and it's no use, I do need to change my setup. //content.invisioncic.com/y282845/emoticons/frown.gif.a3531fa0534503350665a1e957861287.gif My front stage just overpowers the sub. I was hoping some tuning would give me a volume increase but I think I've just reached the limits of the sub, as a bit of distortion pops up if I turn anything up more. Zut alors.

 

[VWBobby 10+ year member]

-01limited-, wow I couldn't agree with you more. Thanks for straightening out our little friend..... //content.invisioncic.com/y282845/emoticons/wink.gif.608e3ea05f1a9f98611af0861652f8fb.gif

The chart I was referring to earlier was the one that someone above posted. Good work. //content.invisioncic.com/y282845/emoticons/smile.gif.1ebc41e1811405b213edfc4622c41e27.gif

If you want to set your sub with your volume at a lower setting, you're going to need to increase your gain a little higher than normal to compensate.

Set your HU at 20 (or wherever you like) and adjust your gain until your sub is as loud as you need it but don't go past 75% gain if you can help. Most amps introduce noise and hum at anything around this level.......Most high quality or clean amps don't. When you're running your HU at 14, there's no way you're clipping it if it was adjusted when it was at 20.

As long as you don't turn your HU up past 20, you won't be clipping your sub, with the gain set correctly for this level.

To figure your amperage, you are going by your voltage at the given load.

Watts = Amps x Volts x Length of wire (resistance, or in your case impedance of your subs)

If you're trying to set your gain to your HU output, you have to measure your RCA voltage, not your voltage at the speaker terminals of the amp!

http://www.the12volt.com/ohm/ohmslawcalculators.asp

 

[Heeltoeclutch 10+ year member]

I'm pretty sure the sub is distorting when I turn it up to 15+. The amp is a SQ beast and I'm pretty darned sure its not clipping. I think I'm just expecting a little too much from the sub. //content.invisioncic.com/y282845/emoticons/tongue.gif.6130eb82179565f6db8d26d6001dcd24.gif I have 4V preouts... the sub is 200 RMS, the amp is rated at 375 RMS @ 1 ohm at 12.2V. So... I could potentially give it easily over 400, but with the gain at 1/3 and HU volume at 15-16 the sub begins to clip I believe. Unless it's somehow the regular excursion noise (which is rather high, even at low volumes)... If that's not clipping I don't know what is... tisn't exactly pleasant. //content.invisioncic.com/y282845/emoticons/tongue.gif.6130eb82179565f6db8d26d6001dcd24.gif Def. don't want to hurt the sub.

When I decided on this setup, I thought it'd be fine cuz I thought I wasn't really one for massive deebeez. I guess if they sound good then I am more of one than I thought //content.invisioncic.com/y282845/emoticons/tongue.gif.6130eb82179565f6db8d26d6001dcd24.gif

 

[VWBobby 10+ year member]

Could be overdriving the sub, not clipping it.... If its a 200 RMS sub and you're feeding it 400RMS, it could easily be bottoming out on the low notes or hating life when expected to change excursion so fast (distortion). Sealed boxes will tend to handle more power than a ported one. Some subs can handle many times their RMS power, others cannot unless very select material is being played (nothing too loud)

 

[Heeltoeclutch 10+ year member]

Could be overdriving the sub, not clipping it.... If its a 200 RMS sub and you're feeding it 400RMS, it could easily be bottoming out on the low notes or hating life when expected to change excursion so fast (distortion). Sealed boxes will tend to handle more power than a ported one. Some subs can handle many times their RMS power, others cannot unless very select material is being played (nothing too loud)

That's why I've been paranoid with the gains... going past 1/3ish causes distortion at regular - high volumes and 1/3 is a bit too quiet. //content.invisioncic.com/y282845/emoticons/tongue.gif.6130eb82179565f6db8d26d6001dcd24.gif You can tell it's there; if you turn off the sub at the HU there's a chunk missing, but it's not present how I'd like it to be.

 

[VWBobby 10+ year member]

Ok, that's a classic case of the sub distorting for the amount of power/program material. Lets say you have a crappy 2.1 channel desktop computer speaker set and you play Bass Mekanik through it. //content.invisioncic.com/y282845/emoticons/smile.gif.1ebc41e1811405b213edfc4622c41e27.gif The sub is going to sound like crap at anything but low volume levels, compared to a higher quality/power home theater sub.

Only way you can run it is to back off on your gain and try to set your SSF up around 20hz+ if possible. Setting your SSF up higher is a way to "cheat" by cutting out any extremely low frequencies. Then the power can be focused on the 20-60hz level and no stray power outside that range.

 

[Heeltoeclutch 10+ year member]

Thanks bobby I wasn't making that connection - that would be fabulous if I had a SSF //content.invisioncic.com/y282845/emoticons/thumbsup.gif.3287b36ca96645a13a43aff531f37f02.gif

If I could change one thing about my HU it would be to add that. //content.invisioncic.com/y282845/emoticons/tongue.gif.6130eb82179565f6db8d26d6001dcd24.gif

Another thing is that I want to hit those lower notes... more conical area-ness and ported...