1999 Chevrolet Blazer

[gckless 5,000+ posts]

That Levi looks so damn sexy. And yes I got lucky and am able to drive home today so progress will be made on them doors my man. Will have pics posted here once there is anything worth looking at:

Lookin forward to it!

 

[gckless 5,000+ posts]

[/COLOR]Aaaaalright, pretty big update. Finally got all my tools to test and tune, including this guy:



So I scoped my HU first. Did all three pre-outs. Got some weird things on the high (tweeter) channel. It wasn't clipping, but above 52/62, I got distortion at the peaks of the waves. I can't figure out how to get pictures on the scope off of it yet, but it looked like this:

@keep_hope_alive or @maylar can you help me interpret that?

But the mid channel never clipped or got distorted. The sub channel had no clipping at 60/62, but hard clipping at 61/62. I set all gains at 51/62 because of the distortion I was seeing on the tweeter channels.

So then I set my gains. EQ was flat, so I sent 110W to each mid, and 70W to each tweeter. I'm sending about 4500W at 0dB (which is about 2300W at -3dB) to the subs. Then I ran the auto T/A and EQ on the 80PRS. It does a couple things that you have to go back and look for, like sub LPF and mid HPF and slopes.

When you're looking at these RTA graphs, pay attention to the blue top lines. those are the peaks, and the results from the sweep. I took these pictures after the sweep was done, at volume 0, which is why the red bars are so low.

So, first I RTA'd the low end, ran a 20-250Hz sweep. Got this:



Kinda don't know why I did that. I then ran a 2 minute 20-20kHz sweep. This is the result:



Determined that the sweep was way too fast for the mic/software to pick up on the lower end. So then I cleared the RTA, broke it down, and ran a 90 second 20-1500Hz sweep. Then I kept the results, and ran a 90 second 1000-20000Hz sweep. This gave me accurate results across the whole range, that look like this:



I just need to cut at 1kHz and 2kHz, and I should be sounding pretty good. It already sounds great, and the cool thing is I can hear the peaks at 1k and 2k.

Here's a quick video:

Full System Tune - 14Sep2013 - YouTube

Gonna clean the wires tomorrow.

 

[keep_hope_alive Premium Member]

i think you may be seeing artifacts of slew rate at high amplitudes causing distortion and harmonics. the harmonics are what you see on the waveform.

looks like a troublesome 150hz peak (i struggled with that until recently). and some interference going on around 1kHz.

 

[gckless 5,000+ posts]

i think you may be seeing artifacts of slew rate at high amplitudes causing distortion and harmonics. the harmonics are what you see on the waveform.
looks like a troublesome 150hz peak (i struggled with that until recently). and some interference going on around 1kHz.

Gotcha. In any event I set max volume below that. How did you get rid of the 150Hz peak? I'm assuming that's install work. I honestly can't hear that though, and I don't want to cut at 125Hz. And for the 1kHz, I just cut at 800, 1.2k, and 2kHz, cut each one notch. It sounds better to me, but what's the proper way to fix it?

 

[gckless 5,000+ posts]

Zed issues v.2:

http://www.youtube.com/watch?v=lVYU42yfaXI&feature=youtu.be

I have no idea what it. @hispls ; you ever seen this? Or anyone else?

 

[gckless 5,000+ posts]

So apparently that light is an indicator for when the high voltage rails are turning on, or something to that effect. Which is cool, nothing wrong with that, actually a nice feature. But what is wrong is the fact that the amp kinda resets, or output at least flickers, when those rails switch off.

Of course, I don't fully understand how all that works, so this might not be accurate.

 

[hispls 5,000+ posts]

So apparently that light is an indicator for when the high voltage rails are turning on, or something to that effect. Which is cool, nothing wrong with that, actually a nice feature. But what is wrong is the fact that the amp kinda resets, or output at least flickers, when those rails switch off.
Of course, I don't fully understand how all that works, so this might not be accurate.

I replied to your other thread about this. Stephen told me that these were diagnostic lights for HIS benefit when testing. That amber light shows you when it jumps to the higher rail voltage state. It is interesting to see how loud you can actually get before that starts to be needed.

 

[gckless 5,000+ posts]

I replied to your other thread about this. Stephen told me that these were diagnostic lights for HIS benefit when testing. That amber light shows you when it jumps to the higher rail voltage state. It is interesting to see how loud you can actually get before that starts to be needed.

That's true, it was pretty **** loud. That's why it's so efficient //content.invisioncic.com/y282845/emoticons/smile.gif.1ebc41e1811405b213edfc4622c41e27.gif

But there is definitely a rail switching problem. Will have to get it sent back more than likely, but I'll speak to him first.

Either way, a Zapco Z-150.6 might be in my future //content.invisioncic.com/y282845/emoticons/biggrin.gif.d71a5d36fcbab170f2364c9f2e3946cb.gif

 

[keep_hope_alive Premium Member]

Gotcha. In any event I set max volume below that. How did you get rid of the 150Hz peak? I'm assuming that's install work. I honestly can't hear that though, and I don't want to cut at 125Hz. And for the 1kHz, I just cut at 800, 1.2k, and 2kHz, cut each one notch. It sounds better to me, but what's the proper way to fix it?

i made a substantial upgrade to my speakers.

i also used green glue damping adhesive between my speaker mounting baffle and the door baffle.

 

[gckless 5,000+ posts]

Got the Levi back tonight. No pics, but it looks the same. This was written on the contact info page I sent with the amp:



Installed it, functionally it seems fine so far. Got my fingers crossed, because if I have to take this out again, it's getting replaced with a Zapco.

Got it tuned up a bit, had to run the auto-EQ twice because the first time was complete booger. Here's what I am getting on the RTA (and again, pay attention to the blue lines):

This was my first full-range sweep after the auto-EQ:



Sub was too high, and there's a bunch of things to fix.

Then I did a 20-1500Hz sweep. Sub was too high, but ignore that for now. This first sweep was at 80Hz crossover point:



Compare that to the same sweep, same volume, only crossed at 63Hz this time:



Much smoother transition between the drivers. Looks like my sub falls off quick after around 65Hz or so. Gonna confirm this tomorrow and run a sweep with the sub running without a LPF. Either way, I like crossing at 63Hz right now. Smoother transition, my mids can handle it, and I can get a little more punch out of the subs before localization kicks in.

After about an hour of tuning and playing around, I am left with this today:



Pretty sure I'm just gonna bump up the level on the tweeters one notch and see how that does.

One thing I did notice when setting gain with a 0dB track is that it started to clip around 36V on a bridged channel, which is around 160W at 8ohms, which is much less than what I should be getting. It's possible I was screwing something up, so I'm not blaming the amp, and it's really not even an issue right now as my mids are really moving set at around 110W, but it's something I want to test.

 

[gckless 5,000+ posts]

Played with T/A tonight! Kinda embarrassed to admit, was my first time actually adjusting T/A. And I think I got it adjusted pretty **** well actually. The auto-T/A on the HU really screwed it up, my driver mid was set at 75" for example. So, I just played around a little, used the distance it set for my driver tweeter as a distance, and just kinda measured the rest with my arm. Played with the distance around where I thought it should be, and eventually nailed it down pretty decent IMO. I really wished I had a dude into SQ here so I could bounce ideas off of him and get feedback.

Then I moved to my EQ. Used pink noise this time. I played around for a few minutes, and found a lul at around 100Hz. So, turned off my subs, and here's the graph I have:



Turned my subs back up to SQ level (which is a **** hair above 1/4 on my PAC LC-1), and here is my graph as it stands:



I see three problems:

- There is a lull at 100Hz

- Spike at 150Hz

- Spike at 1kHz

I'm pretty sure this is all due to installation. There's not a whole lot I can do right now (that I know of). I should be getting my door panels back soon, so hopefully that will solve one or both of the lower frequency anomalies.

All in all I'm very happy with it after tonight.

 

[gckless 5,000+ posts]

Looks pretty good at night //content.invisioncic.com/y282845/emoticons/smile.gif.1ebc41e1811405b213edfc4622c41e27.gif







It's kinda bright though. Might hit the LEDs with some dark blue nail polish and dim them a bit.

 

[gckless 5,000+ posts]

So, figured out my problem with staging: windows. Must be getting nasty reflections, because when the windows are up the stage is a little confusing, not immediately localizable (is that a word?), and scattered. With the windows down, the stage immediately moves to about 4" to the right of directly in front of me, and past the dash. It's magical.

Guess I'm just keeping my windows open from now on //content.invisioncic.com/y282845/emoticons/banghead.gif.8606515f668c74f6de0281deb475b6fd.gif

 

[gckless 5,000+ posts]

Scope time!

So, went out and scoped my Levi. I was only getting around 160W @ 8ohms on a bridged channel (which is rated at 380W @ 8ohms) where the clipping lights came on, so I needed to investigate. What I found was that I was getting much more power capability after the clipping lights came on, with on caveat: I am seeing harmonic distortion.

So here are two videos I shot. Sorry about the poor lighting. Keep in mind that the clipping lights came on the amp around 36V. This was tested with a 1k 0dB tone, and on a pair of channels bridged.

http://www.youtube.com/watch?v=DW0VFXOGP6E&feature=youtu.be

http://www.youtube.com/watch?v=l24HcfUwDM4&feature=youtu.be

Now I know it's the amp inducing the harmonic distortion. Verified by putting HU on volume 20/62, where there was no distortion at all, and then turning the level up on the amp. I also then turned the HU up to volume 50/62, and turned the amp level down to where distortion went away. Both times distortion started at ~16VAC.

On the plus side the amp has much more power than I thought (based on the clipping indicators), if I don't mind that distortion. I honestly can't hear it, so.....

Couple questions:
- What would make an amp do this? Is it truly a bum amp altogether?
- Why would the clipping indicators be lighting up that early?
- Is this distortion bad? Should I even mind it?
- What are your recommendations?

I'm seriously considering going with a Zapco Z-150.6, and will more than likely swap out shortly.

@TaylorFade ; @keep_hope_alive ; @ciaonzo ; @hispls ; @maylar ; @Anyonewhocanhelp

 

[ciaonzo 5,000+ posts]

So, figured out my problem with staging: windows. Must be getting nasty reflections, because when the windows are up the stage is a little confusing, not immediately localizable (is that a word?), and scattered. With the windows down, the stage immediately moves to about 4" to the right of directly in front of me, and past the dash. It's magical.
Guess I'm just keeping my windows open from now on //content.invisioncic.com/y282845/emoticons/banghead.gif.8606515f668c74f6de0281deb475b6fd.gif

I have this exact problem, very frustrating .
I am well impressed with this setup!!!

As far as the amp inducing those harmonics, best I can guess is it could be something to do with the comparator. Either that or it's simply the limitations of this full range Class D design.