i've done a lot of different ways of measuring gain: dmm, oscope, tones, etc...

the most beneficial to me was simply connecting the drivers, turning the gain up and listening to see when I heard white noise through the drivers (ie: floor noise). When I got to a point where it was just below audible from the driver's seat, I stopped and left them there. I then did level matching based on the highest output driver (ie: lower gains only, never raise them).
The potential issue with this is if you have a really low SNR vs. output, but I highly doubt anyone will run into that issue.

my $.02.

 

i've done a lot of different ways of measuring gain: dmm, oscope, tones, etc...

the most beneficial to me was simply connecting the drivers, turning the gain up and listening to see when I heard white noise through the drivers (ie: floor noise). When I got to a point where it was just below audible from the driver's seat, I stopped and left them there. I then did level matching based on the highest output driver (ie: lower gains only, never raise them).
The potential issue with this is if you have a really low SNR vs. output, but I highly doubt anyone will run into that issue.

my $.02.

+1 !!

I'm using 3 way+sub all active.
First i listen to white noise in the tweeter using above method.
Then i adjust the gain for midrange, midbass, sub by measuring the response - relative to the tweeter.

 

i try to keep the gain as close to 0 as possible, i have my bitone set to put out a max signal (4 volts rms) at a 0 db recording at 48 volume on my pioneer f90bt. my gains are just around 0-1/4. personnaly i use the SD card slot and usb of the deck, and the output level is not as high as CD, i have had to use SLA a bit for that, on the deck.

i pretty much just do it by ear. like bikin said, keep the floor noise down, but still retain good enough output. if you have been in car audio for a while you can tell when you go to high and are sending a clipped signal.

 

Same here.... I usually try to keep them closer to "0"...

 

Combination of both.

In a retail environment, O-scope / sine wave then adjust down from there to balance. It tends to be pretty conservative and also leads to longer life of equipment to an abusive consumer (as long as said consumer a: doesn't screw with gains, and b: listens to source material that is at least somewhat clean)

In my own car, use the Scope as a reference to get a base line, then go by ear from there.

 

where is the choice for "using test tones and my ears"?

 

Ow, then it's slightly different with mine.
But the idea is same i guess... noise floor

In contrast, i put the HU in aux mode so the zero bit detector doesn't kick in, and put the volume at least 75% then listen to the noise floor.

 

Here's a method learned from Mark Eldridge at a get-2-gether. To use this method you'll need a radio shack mini-amp and a test disc. Also possibly a voltage divivder, which is pretty east to construct.

The first thing to do prior to setting gains is to set all pre-amp levels and EQ’s to flat (zero) on HU and processors. Secondly, any electronic crossover settings should be adjusted to include the frequency of the test tones that will be used to set gain. For example, my subwoofer output is usually set to low-pass at 63 or 80Hz. For setting gains on the sub channel, I will use a 100Hz test tone, so I will adjust the low-pass for my sub output to 200Hz.

Once the adjustments have been made, you’re ready to pop in a gain setting CD such as Autosound 2000 Disc 104. Gain settings should be adjusted from the beginning of the signal chain to the end. So, you’ll want to start at the HU(s) and work your way through processor(s), then to the amplifier(s). The gain for each channel (or channel pair) should be set using an appropriate test tone. By appropriate, I mean the test tone should be a sine wave at a frequency within the usable range of a particular channel (see note on crossover settings above).

I use a 3-way active HU, so I have High, Mid, and Sub outputs. I will set the gains of these outputs using 100 Hz, 1 kHz, and 4 kHz respectively. I will also be using a test tones recorded at -5dB. This will allow some minor clipping when driven to maximum levels, but any distortion should still be inaudible. The Autosound 2000 Disc 104 includes multiple tracks that will allow for overlap. Gain overlap will allow the user to extract every bit of undistorted power out of their system. The table below illustrates the pros/cons of using overlap when setting gains.

Note: The mini amp can’t play the 100Hz tone with much output at all, so it’s likely necessary to place the speaker of the mini amp closely to your ear before setting the gain. The change in pitch that occurs when the signal begins clipping should be audible.

0 dB Overlap No-clipping, but good amount of power unused +/- 0.1% THD
5 dB Overlap Minor, inaudible clipping (Good compromise) +/- 0.3% THD
10 dB Overlap Clipping is audible (Max. overlap to set gain) +/- 1.0% THD
15 dB Overlap Noticeable clipping is present +/- 10% THD

With all of the preliminary stuff out of the way, it’s time to determine at what volume level our HU starts to distort. The mini amp is connected to one of the mid channel(s). The min amp is to be powered on, but the volume should be kept to it’s minimum (turned all the way down) to avoid hearing the internal amp clip, as opposed to the incoming signal. With a 1kHz test tone playing, the volume of the HU is increased until the pitch of the tone from the mini amp changes. If the HU reaches full volume without this occurring, that HU doesn’t clip. If there’s a slight change in pitch of the tone from the mini amp, the volume of the HU should be reduced to the point just prior to the change in pitch of the test tone. This is the HU’s maximum, unclipped output (MUO) setting.

Note: The change in pitch heard from the mini-amp, indicates the point at which the signal begins to clip. The observed change in pitch comes from second, third, and fourth-order harmonics which occur with clipping. So instead of hearing a single-frequency tone, we hear multiple-frequency tones playing together.

This process is to be repeated, in order, down the signal chain. So any processors between the HU and amplifier(s) are to be tested with the mini-amp and test tones. Remember to use an appropriate test tone for each channel being used (i.e. 100Hz for sub, 1kHz for mid, and 4kHz for the high channel(s)). When setting gains on processors in the signal chain, the HU’s volume should be set to the MUO, as determined previously. The gain controls of the processor being set should be set for the MUO. If the output of the processor clips even when its gain is set to the minimum, the HU’s volume may need to be reduced below the MUO.

Once the gains have been set to MUO on the HU and any processors in the signal chain, the amplifier is ready to be adjusted. Since the output of the amplifier is much greater than the pre-amplified signal, its voltage must be reduced prior to feeding it into the mini amp. This is accomplished by using a voltage divider. I am using a 10:1 voltage divider to set gains for my amplifiers. Depending on the output of the amplifiers being adjusted, a larger voltage divider might be necessary.

The voltage divider is placed inline, prior to the mini-amp. The inputs of the voltage divider are connected directly to the speaker outputs of the amplifier. The HU is once again, set to its MUO. The amplifiers gains are adjusted using the same test tones as before. Once the gain pots on the amp have all been adjusted for MUO, you’re done.

NOW, you can go set you EQ, but remember that any boosts will cause the signal in that range to exceed MUO earlier. To avoid this scenario, only use “cuts” in EQ, as opposed “boosts”.

 

The first thing to do prior to setting gains is to set all pre-amp levels and EQ’s to flat (zero) on HU and processors. Secondly, any electronic crossover settings should be adjusted to include the frequency of the test tones that will be used to set gain. For example, my subwoofer output is usually set to low-pass at 63 or 80Hz. For setting gains on the sub channel, I will use a 100Hz test tone, so I will adjust the low-pass for my sub output to 200Hz.

firstly, i've read that method here, perhaps you should've linked to it so others may read the thread if they choose. secondly, i don't get why you would set the LPF for the subs at 200hz, use a 100hz tone to test with, then cross it at 63 or 80 or whatever for musical listening. what am i missing?

 

ah yes, i forgot about some HUs zero bit mute function. t3sn4f2 made a track that supposedly gets by this by being just "loud" (used loosely) enough to not have that kick in. the link still works as i have just tested it, however i do no know if this truly works since there are no replies to confirm it working nor does my source have the muting function.

 

Ear.

 

the system I have now im actually leaving the gains down all the way and adjusting with xover levels. I have 650 watts on tap per mid and who really needs that much lol. I bought just to have the extreme headroom.

 

I just set it by ear to a particular volume level on the HU... and I don't allow any kids to be in my car if I'm not in it too.

 

The proper way to answer this is to pick: 2nd and 4th choices.

Here is why you need 2nd option:
You have 3 subwoofers getting amplified by separate monoblocks. The proper gain setting is somewhere in the middle. How much do you turn the knob? Do you do it by ear? The proper way is to play a 40hz tone and measure the V on the terminals with speakers connected.

Here is why you need 4th option:
There is subjectivity involved. For example Bikinpunk hates background static. I do too, but I'm not willing to live with the compromises of low gain levels. For one, I have lots of test CDs recorded at very low average volume levels. Whenever I take them into other people's cars I need to max out their volume knob to get any acceptable output. In my car I'd rather live with high background noise but have the complete freedom to adjust the output level as high as I want on any material. I generally have the engine on and covering distance when I'm in my car so the static is almost never heard.
Both options are fine here, but the ear dictates final SPL.

 

Here is why you need 4th option:
There is subjectivity involved. For example Bikinpunk hates background static. I do too, but I'm not willing to live with the compromises of low gain levels. For one, I have lots of test CDs recorded at very low average volume levels. Whenever I take them into other people's cars I need to max out their volume knob to get any acceptable output. In my car I'd rather live with high background noise but have the complete freedom to adjust the output level as high as I want on any material. I generally have the engine on and covering distance when I'm in my car so the static is almost never heard.
Both options are fine here, but the ear dictates final SPL.

I wouldn't be so certain that my setup doesn't get plenty loud.
My typical volume is maxed at 30/40 when driving. The extra 10 volume steps are there for what you mentioned.

Stopped, ie: demoing or at a comp, the volume is typically at about 25/40 and for the louder 'linearity' portion of the testing it's probably about 33 or so. So far, I've not had anyone say that the volume is lacking.
But, I do see where you might feel that it would be. The goal for me is ability to crank it without sacrificing via noise floor. Depending on what components are used, it shouldn't really be a big issue for others to do the same.

Plus, one can tune a car to sound louder than another setup that is EXACTLY the same, minus EQ settings.

 

good stuff. I just usually use my ears and have never had a problem.

 

i run the least amount of gain on the amp as possible; if you do the oscope method and have an active setup then you'll wind up with say your tweeters being VERY loud compared to everything else in the system; then you'll have to lower the level with your proc/crossover and that could result in hiss/noise.

the best way i've found when running active with different amps/speakers is set the gains about 1/4 (if you have a high voltage (5v+) source) then set the levels in the processor/crossover with pink noise and your ears or rta (phone rta works wonders). you'll wind up with some drivers needing more and some needing a lot less. i wound up with ZERO gain on my tweets on a ppi art a200, and about 1/8 gain on my mids on 2ch off a pg xs4600 and my mids need about 1/2 gain on the other two channels on my pg amp. All of this results in a -0 level for all channels on my rf 360.2. I could turn up the amp gains a little bit higher but right now i'm PASSED the limit of my weakest set of drivers (midbasses) so until they're upgraded they'll sit there. plus as it sits my system gets louder than i can stand for any long period

 

Basically the same as Erin. I use a zero data track and start with my gains down to lowest setting. I raise them until I 'think' I begin to hear some noise then stop. I run back down a slight twist then back up and back down to be sure I'm where I want to be. Bridged amps I do the same but one side at a time. Then use a MM to set the 2 channels the same using the lowest value. Then I gain match my drivers using pink noise doing one side (left / right) at a time. Then I set a close to center stage using the driver levels on my HU for each driver equally. Then I move onto TA....then EQ...then the sub in the final stages of my settings.

I went too far I know.


Chuck

 

Dynamic track....ears and eyes.

 

when i start smelling hot voice coil i'll usually turn it down

 

Doesn't work so well for mechanical damage. It doesn't take a lot of power to destroy a speaker with subsonics.

 

It's a balancing act between the output of the HU and amp gain for me.

I currently have my amp gain turned down to about 50% gain. If it goes up any higher, I lose all reasonable granulation between volume steps on my HU volume controls. (ie - one step down its not loud enough, next volume step up and its too loud). I set the amp gain by running up the HU volume control to about 2/3 maximum and adjust the amp gain to a comfortable / typical listening level. I now have finer granulation between volume steps and have some head room for louder listening sessions.

Another issue to consider is the quality of the volume control / attenuation. Coming from the home audio side, from what I've read, the best SQ is achieved with minimal volume attenuation. Cheaper volume control pots when used with a heavy hand (say first 1/3 of volume range) can degrade the sound quality. With higher quality pots or digital attenuation this isn't as much of a concern. The closer the volume control is to wide open (least attenuation) the better the SQ should be (in theory).

Is there a typical volume control assembly used in modern HUs (ie like an Alps pot or?).

Kenreau

 

I thought you were just supposed to match the your amp gain to your RCA inputs coming from the HU? For example, my pioneer is supposed to put out 4V and the max gain on my amp is 4V (Arc Audio XXD4080) so does that mean im just supposed to put the gain on my amp all the way up? Wont the amp be clipping if I do that?

 

I thought you were just supposed to match the your amp gain to your RCA inputs coming from the HU? For example, my pioneer is supposed to put out 4V and the max gain on my amp is 4V (Arc Audio XXD4080) so does that mean im just supposed to put the gain on my amp all the way up? Wont the amp be clipping if I do that?

The 4V setting on your amp is the max input. Therefore, you need to leave your gains all the way DOWN (theorically).

Kelvin

 

I turn off the sub, and adjust the speaker gains with the aim that when the HU volume is close to max level my ears can't take it any more. Then I turn on the sub and set its gain to blend with the rest of music.

 

ADOPTED!!!

 

I use my ears only cause its faster/easier. Basically good enough, nothing else about my car, system or my hearing is perfect so no reason my gain needs to be perfect either.

 

KISS method. Keep It Simple Stupid.

 

im new here and still trying to find out how this forum works but thanks for all the wisdom

 

Well at least we know your a "bass lover". Hit up the SPL area and get educated. Unless you want an all around approach, then WELCOME!!!! and ask as many questions as possible.

 

I use my ears because I do not have the tools necessary to do a proper gain setting. But you are using your ears anyway to listen so that is what I feel should be used if you can't use the proper tools.

 

Can anyone recommend a good True-RMS DMM/O-Scope? Love the Fluke offerings but they are so expensive. Anything $500 and under, though less expensive is appreciated.