setting up line driver

Post by **ttocs** » Fri Mar 06, 2009 7:05 pm

I was wondering what kind of signal would be recomended to help in setting up a line driver(with the peak light)? I am so close to finishing the system that I can almost taste it. I have a few more small areas to smooth over before I can cover the amp rack but I can't freekin wait.....

neverman · Post by **neverman** » Fri Mar 06, 2009 7:24 pm

If you mean the "peak light" on the input device (xover/amp) then I just followed the directions (I adjusted for a ZPX2). I turned the source way up (7/8ths volume) and adjusted for the peak light to flicker at about 1 second intervals (on a known song segment with high output). Anything less and I wasn't driving my input stage well enough and it sounded thin. I'm sure I could've tweeked my gains but I never tried.

It would be really nice to have a scope to make sure no clipping was happeneing during those peaks. I set mine up without one after changing HU's and I don't hear any distortion, however would I hear it if it's just barely clipping? I'd prefer to have as much clean voltage coming out as possible.

Post by **ttocs** » Fri Mar 06, 2009 7:27 pm

and what were you listening too when you did this? It seems that some kind of either white noise might be best but I was not sure.

neverman · Post by **neverman** » Fri Mar 06, 2009 7:51 pm

Damn, call me out why don't you.

I was listening to Kid Rock "Amen" off of "Rock and Roll Jesus" (for the majority of the tuning). Fed off my Ipod at 320kbs. The other test tracks were "Tool, Forty Six and 2" off Aenema , "Jay-Z, Justify my Thug" off The Black Album and "Annie Lennox, No More "I Love You's"" and "Don't Let it Bring you Down" (which has some piercing highs that can hurt if not set-up right), and "I Can't Get Next to You" off Medusa. I base a lot of my system off female vocals and instruments. As well as certain bass notes that HAVE to Hit. "Amen" hits hard when it finally starts. Tool kinda just gets in your face in that aggressive way that is Tool and Annie just makes me smile.

If I get the right feeling of energy off of these tracks I'm usually pretty close to how I want my system to sound.

neverman · Post by **neverman** » Fri Mar 06, 2009 7:55 pm

I've downloaded the Focal test track (or demo) cd's I just haven't converted them yet. I'm interested in what's on them. I found a link on DIYmobile.

I've seen noise tracks as well. I still think I'd like to scope it with real music but it's sounding pretty good atm.

waynehead · Post by **waynehead** » Sat Mar 07, 2009 8:34 am

The few of those tracks that I am familiar with are very dynamic. I would try turning your gains all the way down on your input device, The get some noise to play through. I imagine the focal test discs are more for eqing and gettting your front stage ironed out. Anyway after you get the line driver turned up as high as you can without distortion adjust the rest or your gains. The zpa's from what I hear needs 8 volts.

Post by **stipud** » Sat Mar 07, 2009 9:23 am

Adjust it with your multimeter. Check the How-to/FAQ section.

oldskoolmseriesfan · Post by **oldskoolmseriesfan** » Sat Mar 07, 2009 12:22 pm

waynehead wrote:The few of those tracks that I am familiar with are very dynamic. I would try turning your gains all the way down on your input device, The get some noise to play through. I imagine the focal test discs are more for eqing and gettting your front stage ironed out. Anyway after you get the line driver turned up as high as you can without distortion adjust the rest or your gains. The zpa's from what I hear needs 8 volts.

Im using disc one right now for imaging and sounstage. An excellent choice for tweaking!

gridracer · Post by **gridracer** » Sat Mar 07, 2009 1:06 pm

I downloaded the discs too I just don't know how to convert them or haven't really researched it yet. I won't need them until at least july anyway.

neverman · Post by **neverman** » Sat Mar 07, 2009 1:06 pm

Why would you want a flat pink noise type signal? Don't you need to see what a dynamic track does as it approaches clipping from the line driver? Pink noise stays constant and I can see where it would aid in frequency response dips and such for tuning but I don't see how it would aid in setting voltage gains?

I read through the FAQ a week or so ago, I'll have to revisist it. Didn't I basically achieve the same thing? The lights turn on when they see 11volts. A flicker here and there during highly dynamic passages of music and I shouldn't be clipping right? I would like to know how the supply on my ZPX2 is configured. Does it follow my battery on up and clipping would occur around 14volts or is it regulated down to 12 volts max or some arbitrary voltage? A little headroom is always a good thing. Devices are always more linear while not driven near the limits.

I did start with the gains all the way down on my ZPA's, after I got my line driver to get the ZPX2 lights a flickering I then set the gains on the low pass and high pass up until I heard distortion and then backed them off. I then turned my gains on the amps up just a tad on my highpass for volume and then the sub amp a little more than it's partner for the thump I desired down at around 100hz or so.

I feel close, would a dmm tell me much more? Should I ditch the dynamic tracks (which I tend to favor) and go pink noise or fixed frequency sine-waves? Seems counter intuitive to me. Then again, I'm a noob at times.

Post by **ttocs** » Sat Mar 07, 2009 6:23 pm

I have been installing for almost 15 yrs and NEVER used a meter to tune a system, and never will...... The correct instrument for setting up gains is an o-scope and while you can use a flat-head as a chisel it is not the way it is meant to be used. Do you know if your meter is reading the peak-to-peak ac voltage, the rms voltage or what?

I thought that it would be better to use a tone that would a more consistant output to tune it and then follow it up with some music to do the minor tuning.

dedlyjedly · Post by **dedlyjedly** » Sat Mar 07, 2009 9:06 pm

Cerainly an oscilloscope is the optimal tool for professionally tuning an amplifier, but other methods such as using a dmm are certainly beneficial to those without the equipment or knowledge to accommodate the optimal method. I've got a table-top crt scope at my disposal and have been meaning to splurge for a handheld, but I still use the dmm technique in the install bay at my shop. Unofrtunately time and/or the level of customer appreciation for the best just isn't always adequate for the task at hand.

You've already told us how you would NEVER use a dmm to perform this task, but I have to ask you do you ALWAYS use the scope, or just skip right over the happy compromise and send that shit out the door with a nice tuning-by-ear?

Don't get your feathers ruffled, I'm joking.

Post by **ttocs** » Sat Mar 07, 2009 9:56 pm

my ears are the most important and the most expensive tool in my tool box. After almost 15 yrs installing it has been carefully calibrated to be able to troubleshoot multiple problems at once, on the fly with out needing to worry about making adjustments and being in the correct mode. They can spot an out of phase speaker from 30 ft and hear the beginning of the signal when it is clipped and I have never found a meter that can do this.

I have only had 2 occasions where an o-scope was needed to tune a system and it was when I had multiple amps running multiple drivers to help to balance it all out. I keep hearing it thrown out that the easiest or best way to tune a system is with a meter and I am completely 110% aginst this as most of the people I know do not even know how to really use their meter, and do not have a good enough quality of meter to balance the kind of equipment that we are using here.

neverman · Post by **neverman** » Sat Mar 07, 2009 10:52 pm

I have an awesome meter I'm just a little skeptical on how to properly use it in setting up gains. Especially once frequencies start getting split off via actives. Music isn't a 1khz sinewave. Are these pre-amp stages so consistent that I should just tune for a certain freq. and call it good? I'm asking a serious question here, not trying to mock. i'm trying to learn.

I, was/kinda am still, an electronics tech with a fair level of understanding. Audio wasn't my field, RF/Radar/IR was and now I'm maintaining clean-room equipment which is more in tune with computer and electro-mechanical troubleshooting.

I have access to a nice handheld scope (hell, and an Agilent Infinium ~$50K but that may be overkill

) Then again, knowing where to probe and for what, is key. Sure I'd be able to see clipping going into the amp but what if the pre-amp introduces the clipping before passing it to the output stages? Again... what passages do you test under? Normal tunes or sinewaves? Does it matter? In a normal recording the peak transients don't use the whole amplitude allowed correct? Ideally approaching the top but not being clipped by the mastering process?

I just know for sure my amps lept to life feeding them more voltage on the input. Obviously there is a point where I've gone too far. Where is it and how do I best detect it?

Should I just hook up my DMM and turn off my ears in the short term?

I'm not a professional regarding audio. I just don't want to trash my stuff, however, I don't want it purring along when it should be singing either.

dedlyjedly · Post by **dedlyjedly** » Sat Mar 07, 2009 11:37 pm

ttocs wrote:my ears...hear the beginning of the signal when it is clipped and I have never found a meter that can do this.

No they don't. The output of an amplifier or processor can and will clip prior to audible distortion. To be fair though the meter doesn't "hear" it either.

ttocs wrote: I keep hearing it thrown out that the easiest or best way to tune a system is with a meter and I am completely 110% aginst this as most of the people I know do not even know how to really use their meter, and do not have a good enough quality of meter to balance the kind of equipment that we are using here.

I wouldn't say that it's the easiest or the best way to tune a system. But it is a method that can effectively prevent you from causing your amps/processors to clip while remaining feasible for most people despite time constraints or a lack of more sophisticated equipment. These qualities make it a very good method.

The process of tuning with a dmm (as thoroughly described in the How To section) can be performed with even the most basic dmm by a user that is only familiar with its most basic operation.

dedlyjedly · Post by **dedlyjedly** » Sun Mar 08, 2009 12:56 am

damnit i hate it when you really put some thought and effort into answering some complex questions and you submit the post only to find you've logged out of the forum!

sorry neverman, i tried, but it's late and i'm exhausted. catch up with you guys later.

neverman · Post by **neverman** » Sun Mar 08, 2009 1:15 am

dedlyjedly wrote:damnit i hate it when you really put some thought and effort into answering some complex questions and you submit the post only to find you've logged out of the forum!

sorry neverman, i tried, but it's late and i'm exhausted. catch up with you guys later.

Damn it... I hate that too! But, you still owe me

I really would like help as I offer debate in return... like I already admitted, I'm semi-trained, have the equipment available and the skills (plus loads of time) and I still don't really know the proper way, or maybe even the best way.

Thanks in advance!

Post by **ttocs** » Sun Mar 08, 2009 6:26 am

in debate then as well as because I can't remember, do you happen to remember if a digital meter set to AC voltage reads the voltage peak or the AC rms voltage(.707Vp)? If I remember correctly from school it shows the rms voltage output.

gkitching · Post by **gkitching** » Sun Mar 08, 2009 6:36 am

ttocs wrote:my ears are the most important and the most expensive tool in my tool box. After almost 15 yrs installing it has been carefully calibrated to be able to troubleshoot multiple problems at once, on the fly with out needing to worry about making adjustments and being in the correct mode. They can spot an out of phase speaker from 30 ft and hear the beginning of the signal when it is clipped and I have never found a meter that can do this.

OOOOOOOOOO

What are you one of those guys thats like 5' - nothing with a Napoleon complex that feels the need to turn every conversation into a big dick contest?

Well you win .. You're a big dick!

Post by **stipud** » Sun Mar 08, 2009 9:17 am

gridracer wrote:I downloaded the discs too I just don't know how to convert them or haven't really researched it yet. I won't need them until at least july anyway.

The Focal discs are recorded in Apple lossless, which means you retain the full CD quality. Just install iTunes, burn them to CD, and uninstall iTunes if you don't want it anymore. Converting them to MP3 would lower the quality substantially.

neverman · Post by **neverman** » Sun Mar 08, 2009 9:26 am

It's measures the rms values... pretty sure that's what I remember. Schooling was 20 years ago or so

Post by **stipud** » Sun Mar 08, 2009 9:47 am

Regarding setting your gains...

First of all, clip lights are not super accurate, especially on dynamic music. Neither are your ears for that matter.

I would personally not recommend using highly dynamic tracks to set your gains. You might end up setting them in such a way that the base level of the track is well below clipping, and there is only "light" clipping on high dynamic peaks. However, when you get a highly compressed recording (like the new Metallica album

), or MP3s, etc., the base recording level is now much higher than it was in your dynamic track, and now you will be clipping all over the place. So for setting your gains by ear, you want to use a very LOW dynamic track, which will ensure that compressed and uncompressed recordings are both safe. Here's an example of track compression:
http://www.youtube.com/watch?v=3Gmex_4hreQ

If you imagine that you have light clipping on only the highest -0dB peaks in the dynamic recording, now think about what will happen with the compressed one, when the entire base signal is brought up to -0dB

If I set gains by ear, I do it with a -0dB 1000Hz tone. That's as simple as you can get. This way, you can hear clipping far more obviously, since the sound of the signal audibly changes, instead of simply getting louder. I have found this is fairly reliable. If I turn the gains down a hair below the audible distortion point and verify with a DMM or scope, I am usually pretty close to the rated output.

However, on sub-bass, the human ear is much worse at picking up distortion. The rule of thumb is that the human ear can hear over 1% distortion on midrange, but up to 10% on sub-bass. I did an experiment with me and my friend as guinea pigs. I ran a 60Hz tone through my sub, and we both adjusted my LPL to the highest point, until we were certain there was no audible distortion. However when I hooked up his oscilloscope, the signal was visibly clipped. PG's amps clip soft, so especially with bass it's very hard to tell by ear until you're passing a near square wave signal.

Using an oscilloscope is the best way to set your gains. That way you work from the front to the back in your chain, setting each device at it's peak gain, before you can visibly see clipping. This gives you the maximum possible output from each device, and thus the lowest possible noisefloor. However, most of us don't have the luxury of an oscilloscope.

A multimeter is a great way to measure the RMS output of your devices. You work from the front to the back, using the RMS output of your devices as a benchmark for setting the gains. This way, as long as the rating is accurate, you will not be clipping. Unfortunately almost no headunit voltage ratings are to be trusted, which is why we use 3/4 volume as a rule of thumb. Now with a -0dB 60Hz tone playing out of your HU, you set the gains on the next device (your line driver). Here you will keep increasing your gains towards the rated output of the device. However, you should now pay attention to your clip light. On test tones it is far more accurate, and will glow solid if there is even a bit of clipping. I found that my Audiocontrol Three.1 had a rated output of 9v, though the clip light would go solid at 5v. If I set the gains to 9v, distortion was audible, so I knew the clip light wasn't lying. So I left the gains down at 5v (just before the light turns on), and compensated by increasing the gains at the amp.

Now unless you have a True RMS DMM, you will have to use a 60Hz test tone. This means to set the gains on your component amp, you need to bypass the crossover somehow. Once the gains are set, you can re-enable it, and it will be set just fine for higher signals, since your amps should be +-1dB 20Hz-20kHz.

If you want to do an experiment, set all your gains by ear, then disconnect your speakers and run a -0dB 60Hz test tone and verify with a DMM where you have the gains set. I wouldn't be surprised if you are well over the device's rated outputs. Dako, for example, just installed his TLD66 by ear, and when he set the gains with a multimeter, he found it was trying to push 15 volts at -0dB!
http://phoenixphorum.com/finally-got-ar ... t9204.html

Post by **ttocs** » Sun Mar 08, 2009 10:19 am

gkitching wrote:
ttocs wrote:my ears are the most important and the most expensive tool in my tool box. After almost 15 yrs installing it has been carefully calibrated to be able to troubleshoot multiple problems at once, on the fly with out needing to worry about making adjustments and being in the correct mode. They can spot an out of phase speaker from 30 ft and hear the beginning of the signal when it is clipped and I have never found a meter that can do this.
OOOOOOOOOO

What are you one of those guys thats like 5' - nothing with a Napoleon complex that feels the need to turn every conversation into a big dick contest?

Well you win .. You're a big dick!

Wow, I am really speachless on this one. No, I am 5'11" and 160 and use to not being the tallest or the shortest. Are you the kid that took the names of the kids that did something while the teacher was out of the room?

I think I will stand on the point that it would take one to know one to be polite, and the kindly ask you to sit back and drink a BIG FUCKIN CUP OF SHUT THE FUCK UP! You can post your comments on someone elses post with the idea that if you don't have anything nice to say THEN SHUT THE FUCK UP and stay off my post.

back on topic. I also agree that dynamic songs like a metalica or tool would be a good idea after it is tuned to make sure that the peaks do not go to far but while tuning it would be better to find something that is more consistant. That is why I thought that a white noise track would be better for watching the peak light on the PLD1 as it would be a ver definite point where it would come on and off. I will adjust the gain on the amp by ear as I always have.

neverman · Post by **neverman** » Sun Mar 08, 2009 10:48 am

So if I use my dmm and a test tone (say 1khz), I multiply what it reads by 1.41 and try to approach around 11vac for my system (or 7.5vac read on the meter, give or take)? Instead of bypassing the ZPX2 wouldn't I also try to keep the gain out of it constant or very close to 1 so that I'm driving the input stage of the ZPA's up around where they're happy?

How different in sound is a 1khz tone due to soft clipping? The frequency won't change obviously so it won't be a pitch change. Is it more of a harsh sound that makes one cringe as it gets ugly?

(Pretty sure my DMM is a true RMS type) I'll be sure to check.

Post by **stipud** » Sun Mar 08, 2009 10:58 am

neverman wrote:So if I use my dmm and a test tone (say 1khz), I multiply what it reads by 1.41 and try to approach around 11vac for my system (or 7.5vac read on the meter, give or take)? Instead of bypassing the ZPX2 wouldn't I also try to keep the gain out of it constant or very close to 1 so that I'm driving the input stage of the ZPA's up around where they're happy

Not sure what you're getting at. If you want to reach 11v RMS, you adjust the gains until you hit 11v on the multimeter. No need to multiply or anything, because we want RMS, not peak volts. Of course if your clip light goes solid before you reach 11v, you simply won't get more voltage without clipping.

Also, unless you have a "True RMS" meter, you need to use a 60Hz tone. 60Hz is the frequency of our electrical outlets, so that's what the DMM is calibrated to. Similarly, in Europe you would want to use 50Hz, since that is their electrical frequency. A non-True-RMS meter will not accurately measure the voltage at 1kHz.

neverman wrote:How different in sound is a 1khz tone due to soft clipping? The frequency won't change obviously so it won't be a pitch change. Is it more of a harsh sound that makes one cringe as it gets ugly?

Yep, it just starts breaking up very noticeably. Of course a 1kHz tone played at full volume is pretty excruciating to begin with, and unless your speaker is installed perfectly, you may get lots of rattle and buzz from the install, that you mistake as noise. Because of this, I still consider the DMM more accurate. As indicated in my example, if I set it perfectly by ear, it's close to the DMM rating anyways.