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Help With SQ Tuning

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Elvenking

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Okay, I have gone over many of the threads here and tried a bit of stuff with tuning that sometimes sounded good, sometimes not so much. Let me tell what I am working with so far and see if you can pitch some good ideas.

I want my 2005 Sentra to sound as bad *** as possible. Clear enough request. The last time I really set up a system on my own was back in the early 90's when Class A amps were still going into cars...had some old school HiFonics amps, ribbon tweets, and beefy mids...and we just tweaked until most things sounded good. I keep hearing people say how once you get things dialed in, everything should sound good. I simply cannot see how this is true. All recordings are not created equal and some shops just couldn't mix an album if their life depended on it.....more on this later when I talk about SQ.

So what I have now...

An Alpine Deck (CDE -153BT) that has a 9-band parametric EQ on it with +/-7db adjustability. I have Morel Tempo 6's in (for now) a passive setup with the recommended passive Xovers. Those are hooked to a JL CX360/2 Amp. Then in the trunk I have a Polk DVC 12" that kicks like a mule good enough hooked up to a Kicker 300.1 amp.

What I have coming...

On the recommendation of some pretty seasoned Car Audio members, I have the Pioneer DEH-80PRS coming today....super happy....and I also have a JL Audio 360/4 channel amp coming to allow me to go fully active with the 80PRS.

The current observations...

I am pretty new to adjusting using an RTA...and I know that there are some good steps to take leading up to that step. With a bi-amp network, I can level match with the left and right fronts, and then the rear...which is essentially level matching the amps. I had a choice on the Passive Xovers to either boost the tweets by +3db...or leave em at zero...I left em at zero cause they are in pillars and seem to mix better at 0db. So level matching amps for now until I get fully active.

As far as mounting, The tweets are up in the pillars and the mids are in the kick panels. I don't have it in me at the moment to build pods and I really wouldn't know where to start with a mission like that in a Sentra. However, the positions seem okay and I have indeed gotten some really, really good sound out of it given the right source material. (That 'given the right source material' may play a lot into the discussion). What I am looking for is...

  • A video of someone actually going through and tuning a system flat.
  • What a 'flat' RTA output looks like and what weightings are used.


Why I look for this is the following. What is the tolerance you are looking for in tuning a system flat. I mean...does nothing vary by +/- 3db? When I start with the system flat, I see some things that can vary by quite a bit...and they jump around a lot. Is it supposed to really be flat? I have seem some curves that slope downwards and heard of people saying reduce db output by so much per octave. What is up with that?

Anyway, let's say that I got it somewhat flat...okay. At first, I can say...yeah....I can hear a lot of most everything in the mix. I mean....I listen to mostly rock and heavy metal a la heavily compressed mixes where you won't be creating a sound stage in your head. I don't care...you can have primo headphones on and with really compressed music...things are just fused together and you can hear this in the source material at any volume. With other more dynamic recordings....things are very much more tolerable and something of a sound stage is maintained. What I notice with full saturated bandwidth kind of rock or metal is that flat is just going to be too damned bright in the mid areas. So after I get it flat, I go in and look to make other adjustments....but I can't make them without trading off. If I have to make an adjustment, there is compromise...okay. However, some shrill sounds can't seem to be EQ'd out...either that, or I cannot target the offending frequency....or when I get to the band I think it is...it is already cut hard. I end up playing with controls until I have to start over again which never seems to end up with the same settings each time. What the heck am I looking for here? Also, the Alpine is f**king maddening with the sheer number of clicks to make adjustments. Somehow, I think I am caught between a well-tuned system and also trying to EQ crappy recordings when they come up in my listening. I am an older dood and I have stuff from the 80's forward. I can tell with absolute certainty, that there will be no system on which you can put all these on and have them sound just beautiful....accurate...maybe...but not beautiful.

So I am looking for really detailed use of the RTA and what kind of things you let go...and what kind of things send you into making changes other than EQ. How do I know what I can control and what I cannot? I want some good strategies as I get my proper equipment coming in. You will save the day if you can get me going in the right direction.

Click to read more...
 
I don't know anything about this but I do have a question. Can you give a somewhat detailed like this post review on the morel tempos. Have those in mind to buy.
Click to expand...
I can give a detailed review on them a bit later, but I do know that they were so much better than the Alpines I had in there first. These have pretty crisp and not-harsh tweets, and the mids take some really good power and put out more than I would expect them to. Fine speakers they are.

On the other topic, I did just get my DEH-80PRS and really am impressed with the little time I have spent. The timing correction seemed to make things a lot more cohesive and I simply love the fact that after it gets done auto setting the EQ for best curve...it stores it in its own setting away from user EQ settings....sweet....sometimes I just want to EQ my music without botching the flat reference curve....so that suit me well. I have music too various to never touch my subwoofer levels or to not want to cut the 1-2KHz range on some material...this is fantastic.

 
I posted this in your other thread.

That 80prs will solve most everything.

Glad to hear you got one.

There is a process to set up the system. I'll try and post here.

This is a very basic way outside of dsp and rta.

1. Set desired crossover points and slopes.

2. Check polarity of each set (tweets and mids). Get the track from the iasca, meca, out r somewhere online that says "My voice is in phase, my voice is out of phase") the person should explain how to listen. This is important, if you're speakers are out of phase then everything will be wrong. The 80 prs was made fur these issues. You can invert the phase of each driver separately, which you may need to do to get the track to play right and get your speakers in phase.

3. A. Center frequency bands. Use 1/3 octave test tracks of "uncorrelated pink noise". First, use the 80prs separate L/R level control to center bands. Then, 800hz and below, you must use time alignment to center frequencies further.800hz and above you must use EQ to center frequencies.

B. Start at the 1/3 octave track somewhere at the middrange high pass filter. Start at 200hz. While the noise is playing, shift the noise track to the center of the dash with the separate L/R level control the prs supplies (these features are why you bought this unit). Decrease 1db, increase 1db on either side to shift the noise image to the center. Place something on your dash (bottle cap, penny) to mark the center of the dash, and use the separate L/R level control fur the drivers playing the frequency huge tuning

to move each noise track to the marker you used. Do this until you've centered the best you could with the level controls. (This is what "level matching" is),

C.Now, use time alignment to center bands up to 800hz. This is to increase the center focus where the L/R level method couldn't do completely. add delay to the left Mid in very small increments until the noise moves itself to the center of the dash. You'll literally see the image move.up to 800hz. Move the image to the marker you used.

D. After 800hz, use EQ to center frequency bands. (Thus is the interaural level difference area, and is why we aren't using time but level now. Use the same method as the L/R level control, but here instead of using the 80prs separate L/R volume level control as before, you want to use the separate L/R eq level. As you go up the octaves through the test tracks, you'll notice some frequencies may already line up with your marker. The ones that didn't, +1/-1 on either side of the EQ to bring the frequencies to your center marker.

Your done.

Your system should now sound quite well.

Play the "my voice is in phase" to confirm polarity and center image.

After this there are other fine tuning methods.

I'll see if i can make a video

 
Note.

The initial time alignment you set, as well as your first round of centering bands with separate L/R volume control should get all the frequencies close center. Where you wantyour center is personal preference.

If it's too far right, go back through the tracks and shift the image slightly for all frequencies, play the voice track to confirm.

This is what the 80prs is for.

 
I posted this in your other thread.That 80prs will solve most everything.

Glad to hear you got one.

There is a process to set up the system. I'll try and post here.

This is a very basic way outside of dsp and rta.

1. Set desired crossover points and slopes.

2. Check polarity of each set (tweets and mids). Get the track from the iasca, meca, out r somewhere online that says "My voice is in phase, my voice is out of phase") the person should explain how to listen. This is important, if you're speakers are out of phase then everything will be wrong. The 80 prs was made fur these issues. You can invert the phase of each driver separately, which you may need to do to get the track to play right and get your speakers in phase.

3. A. Center frequency bands. Use 1/3 octave test tracks of "uncorrelated pink noise". First, use the 80prs separate L/R level control to center bands. Then, 800hz and below, you must use time alignment to center frequencies further.800hz and above you must use EQ to center frequencies.

B. Start at the 1/3 octave track somewhere at the middrange high pass filter. Start at 200hz. While the noise is playing, shift the noise track to the center of the dash with the separate L/R level control the prs supplies (these features are why you bought this unit). Decrease 1db, increase 1db on either side to shift the noise image to the center. Place something on your dash (bottle cap, penny) to mark the center of the dash, and use the separate L/R level control fur the drivers playing the frequency huge tuning

to move each noise track to the marker you used. Do this until you've centered the best you could with the level controls. (This is what "level matching" is),

C.Now, use time alignment to center bands up to 800hz. This is to increase the center focus where the L/R level method couldn't do completely. add delay to the left Mid in very small increments until the noise moves itself to the center of the dash. You'll literally see the image move.up to 800hz. Move the image to the marker you used.

D. After 800hz, use EQ to center frequency bands. (Thus is the interaural level difference area, and is why we aren't using time but level now. Use the same method as the L/R level control, but here instead of using the 80prs separate L/R volume level control as before, you want to use the separate L/R eq level. As you go up the octaves through the test tracks, you'll notice some frequencies may already line up with your marker. The ones that didn't, +1/-1 on either side of the EQ to bring the frequencies to your center marker.

Your done.

Your system should now sound quite well.

Play the "my voice is in phase" to confirm polarity and center image.

After this there are other fine tuning methods.

I'll see if i can make a video
Click to expand...

Wow! I am glad I checked back here now. Thanks for the responses. Really appreciate. I have not tried these suggestions yet...but I can tell you that I LOVE THIS DECK!! The timing alignment really did some good for the acoustical phasing issues. Then I made some cool adapters for my pillars to get the tweets on-axis. That is really crisp! It is getting better all the time. Sounds so damned good that it is hard to stay home now. I do trips to anywhere I might need to go...just loving it. I'll have to post a picture of the little pillar mounts I made. Thanks for that recommendation...this HU is super fine. //content.invisioncic.com/y282845/emoticons/smile.gif.1ebc41e1811405b213edfc4622c41e27.gif With the timing alignment....I don't get the shrill interference at certain freqs anymore with rock music....things are more consistently maintaining volume now. Tight as hell!

I am going over to my brothers to install the 4ch JX360/4 on the comps to go active. Then I will run through this procedure you have outlined. Can't wait!! Thanks for all the great suggestions and for taking the time to write this up.

 
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Hey by the way. I also went ahead and got a 4ch amp (JX360/4) to go active on the comps. I am hoping that 70W/ch will be sufficient for the tempo drivers. Let me know what you think. Right now it is a JX360/2 hitting those with 110W/ch...I guess I am technically going up to 140W/ch . Cheers again.
Click to expand...


right now you have 110W/ch into a passive crossover that allows for 110W to the woofer below the crossover point and 110W to the tweeter above the crossover point. if you move to active with the 360/4 alone, you reduce to 70W for the tweeters and 70W for the midbass. when you go active the midbass will get less power than they have now. you'd be better served to keep the JX360/2 on the tweeters active then bridge the JX360/4 to the midbass active. while you don't need/want the full power out of the 360/2 at the tweeters, you do want minimal distortion so the gains will be very low on that amp.

the passive crossovers use resistors to limit power to the tweeters and attenuate them to account for differences in sensitivity between woofers and tweeters. note that how much attenuation is needed varies with install. pointing tweeters at you (on-axis) vs. pointing tweeters away from you (off-axis). as you tune after moving active you'll notice that you may need to attenuate the driver's tweeter separately from the passenger tweeter (depending on how they are aimed).

when tuning, i use an RTA to identify issues then try to fix with acoustical treatments, aiming, and crossover points before resorting to an EQ. the reason is that an EQ is good only for broadband adjustments (1/3rd octave or wider) and many acoustic issues are narrowband (1/24th octave or narrower). also note that many problems have a fundamental frequency and then harmonics that may or may not be mistaken for the fundamental. this is where a narrowband RTA is very useful because it allows you to identify harmonics.

 
right now you have 110W/ch into a passive crossover that allows for 110W to the woofer below the crossover point and 110W to the tweeter above the crossover point. if you move to active with the 360/4 alone, you reduce to 70W for the tweeters and 70W for the midbass. when you go active the midbass will get less power than they have now. you'd be better served to keep the JX360/2 on the tweeters active then bridge the JX360/4 to the midbass active. while you don't need/want the full power out of the 360/2 at the tweeters, you do want minimal distortion so the gains will be very low on that amp.
the passive crossovers use resistors to limit power to the tweeters and attenuate them to account for differences in sensitivity between woofers and tweeters. note that how much attenuation is needed varies with install. pointing tweeters at you (on-axis) vs. pointing tweeters away from you (off-axis). as you tune after moving active you'll notice that you may need to attenuate the driver's tweeter separately from the passenger tweeter (depending on how they are aimed).

when tuning, i use an RTA to identify issues then try to fix with acoustical treatments, aiming, and crossover points before resorting to an EQ. the reason is that an EQ is good only for broadband adjustments (1/3rd octave or wider) and many acoustic issues are narrowband (1/24th octave or narrower). also note that many problems have a fundamental frequency and then harmonics that may or may not be mistaken for the fundamental. this is where a narrowband RTA is very useful because it allows you to identify harmonics.
Click to expand...
Humm...well....I suppose I would have to figure out a way to have all these amps in the car....that'll be a total of 3 amps. What I am wondering is how it will certainly be less power to the drivers...since technically there will be 140W going to each side (70 to mid and 70 to tweet) how that will be less power. I imagine that there is some sort of loss of efficiency in the passive crossover as well as how they get those two drivers to sum back down to 4 ohms together. I am not an expert, but I am wondering the math behind it.

Don't get me wrong...hell...I can probably get the amps in there....but now I am worrying about current draw on my car...is my alternator still gonna be okay? LOL. I am trying to take a little pause on how much I am putting into this thing and it hasn't been working out so well. You see...it all started when the stock head unit in my car stopped playing CD's....and now...well it's just friggin' out of hand man....I just got done turning a couple of 90 degree pipe fittings from home depot into some sweet tweeter mounts...lol. I love it!

817EDEDA-B14B-4852-BBF3-517FC30D59F2.jpg


4775B67E-24BF-4A15-BA99-7042A5ABF6AA.jpg


I'll have to take a few pics of the installed....I was too busy listening to them today to remember pics.

Since I had the thing installed...I have replaced everything with better gear except the bass amp and the woofer. It really is kind of an old habit rekindled if you know what I mean. //content.invisioncic.com/y282845/emoticons/wink.gif.608e3ea05f1a9f98611af0861652f8fb.gif

 
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this is a hobby that tends to take over in the quest for better sound quality. //content.invisioncic.com/y282845/emoticons/smile.gif.1ebc41e1811405b213edfc4622c41e27.gif

i think what you are getting hung up on is that you don't add power to tweeters + power to woofers together to get a total because there isn't an overlap in frequency ranges. consider the image below (random image of crossover slopes). the green line is the response of a woofer, the blue line is the response of a midrange driver, and the red line is the response of a tweeter. the crossover (electric or passive) limits the range of frequencies each driver will play. we we discuss amplifier power we also consider frequency. at 100Hz the amplifier sees only one speaker, the woofer. at 1000Hz the amplifier sees only one speaker, the midrange. and at 10000Hz the amplifier sees only one speaker, the tweeter.

crossover-slope.gif


this is why 70W for tweeters and 70W for woofers is just 70W per side. the reason to go active, for many people, is not for more volume but for more control over the crossover point between the mid and tweeter and, if necessary, time alignment for the tweeters (if their crossover point is low). given your tweeter mounts (i make spheres but your idea is very similar), the tweeters are aimed at you and the nearest tweeter (driver's side) will need to be attenuated in order to center your soundstage properly.

 
this is a hobby that tends to take over in the quest for better sound quality. //content.invisioncic.com/y282845/emoticons/smile.gif.1ebc41e1811405b213edfc4622c41e27.gif
i think what you are getting hung up on is that you don't add power to tweeters + power to woofers together to get a total because there isn't an overlap in frequency ranges. consider the image below (random image of crossover slopes). the green line is the response of a woofer, the blue line is the response of a midrange driver, and the red line is the response of a tweeter. the crossover (electric or passive) limits the range of frequencies each driver will play. we we discuss amplifier power we also consider frequency. at 100Hz the amplifier sees only one speaker, the woofer. at 1000Hz the amplifier sees only one speaker, the midrange. and at 10000Hz the amplifier sees only one speaker, the tweeter.

this is why 70W for tweeters and 70W for woofers is just 70W per side. the reason to go active, for many people, is not for more volume but for more control over the crossover point between the mid and tweeter and, if necessary, time alignment for the tweeters (if their crossover point is low). given your tweeter mounts (i make spheres but your idea is very similar), the tweeters are aimed at you and the nearest tweeter (driver's side) will need to be attenuated in order to center your soundstage properly.
Click to expand...
Yes...I saw your tweeter spheres. If I saw those before I thought up the 90 degree pipe, I would have probably followed that lead. I was looking at your installs and you have a wayyyyy higher budget than I do...LOL.

Okay. Well I will be installing the 4ch amp tonight and I will try to move the Bass amp to under the passengers seat so that both amps for the comps are under the drivers seat. I'll do lie you say and run the 2ch to the tweets, and the 4ch bridged to the mids...I see no issues with power there...I was gonna sell off the 2ch...but your suggestion is going to get some quality time tonight. I got test tracks from the IASCA disc, decent RTA, and a couple of the better active tuning guides I have found on the forums. I will let you know how this goes and I will take some care on my level adjustments. I was concerned a bit with electrical impact. When does one have to begin looking into a beefier alternator?

Also...what is the best way to ground multiple amps in two locations (i.e. Under the driver and passenger seats)?

 
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don't worry about power needs of the tweeter and mid amps - those won't be much at all except for brief musical peaks.

you can ground on either side of the driveshaft hump (used for exhaust in FWD cars). also accessible so you can use a bolt and get a good bite.

 
Just got all installed tonight after about 4 hours of car contorting. Added the new JX360/4 4ch bridged stereo to the mid drivers and the JX360/2 on the tweets....the Kicker remains kicking the 12" DVC Polk which it seems to do quite well for my taste...for now //content.invisioncic.com/y282845/emoticons/wink.gif.608e3ea05f1a9f98611af0861652f8fb.gif. Just removed the seats and went to work. About all I have had time for is a electrical check, power on, left/right check and the fact that each output was going to the right network and xover settings. All checked out. Tomorrow will be some quality time tweaking for sound. No engine whine in the ground...so good for that. I had to come in and pay attention to my lil buddy...an African Grey Parrot named Isaac. I'll tune tomorrow and let ya know how it goes.

About the mid\tweets xover point. The factory passives had them crossing over at around 3.8KHz @ 6db/octave. I definitely want to avoid sending too much lower than that to the tweet correct? I was thinking that a similar xover point would be somewhere around the 4KHz setting on the 80PRS or higher....and I am curious to try optimizing these settings. How do folks usually end up massaging this xover point? Thanks for all your help!

Cheers

Stephen

 
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