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View Full Version : Rear fill gone, now a few questions.



calebkhill
02-09-2013, 11:16 AM
Well not completely gone, just attenuated from my front stage. Using the bridged mono attenuated from here:
GlassWolf's Pages (http://www.glasswolf.net/papers/rearfill.html)

At first the volume sounded lower and the tone was hollow. I figured I just needed to get used to it. So I gave it a days listen. The second day I realized that as the volume level seemed only slightly decreased, everything sounded way more detailed. It was a crisper, defined sound, and the volume decrease must be the decrease in interference: interference = increased levels.
Now that I'm getting more of a grasp on my front stage, I have a few questions.

1.My front door speakers are beside the legs.when I move my leg I hear the change. The legs are getting in the way. Any suggestions to make up for some of this without any major mods to the door panel?

2. Are 2" and 3" full range drivers interchangeable with 1" tweets?

3.How can you set your amps frequencies accurately besides just guessing. Oscope or dmm method?

4. How many and What speaker sizes for the front stage, and crossovers points and slopes would be ideal?

5. Any other hints for setting up the front stage? Am I asking the right questions? Time alignment isn't an option at the moment :( Door treatment will be done later but besides that.

av83
02-09-2013, 11:40 AM
what is your front right now? What, hu, drivers and amp? how are they crossed?

calebkhill
02-09-2013, 12:02 PM
My fronts are coax, but I'm upgrading to comps soon, probably PHD. Two fosgate punch tweets in the dash. 2 15 fosgate subs. Tweets at 3.5khz/12 passive, PhD's will be 63hz-80hz-3.5khz, subs 80hz. Thinking about band passing the doors, but setting amps frequency range is a guessing game it seems.

neo_styles
02-09-2013, 12:25 PM
Well you're sensing the difference when you move your leg because that full range signal is trying to bounce around your leg. Upgrading to components and placing them either in the sail panels or (ideally) at least 2" above the dash should help dramatically with that. As for driver choices, you can really benefit from that midrange/midbass impact by going with the largest driver you can fit in the doors. If I was careful and clever on the VW, I could probably run 8" midranges and just let the passive crossover adjust things for me, but I don't have too much to complain about with what I currently have. If you get the PHDs, just set your HPF and let the crossovers do the rest.

neo_styles
02-09-2013, 12:27 PM
Also, if you have time and patience, I remember reading that you can set your crossover by playing a test tone recorded at your desired crossover frequency then monitoring a dmm while you adjust the crossover point on your amp. You'll reach the right point when the signal cuts down to 1/2 of what it was. Basically how the SMD CC-1 operates IIRC.

neo_styles
02-09-2013, 12:30 PM
Oh and one more thing: I would actually do door treatment FIRST. At least with CLD tile. AT's stuff really isn't that expensive and 24sqft should be more than enough to do all 4 doors. It's a pretty remarkable improvement just from that and will keep you from feeling like you wasted money if you do get those PHDs. They really deserve a good home.

ciaonzo
02-09-2013, 12:46 PM
One thing that's frustrating about forums is that information sharing only goes so far and interpretation ruins a lot of it. I wish I could travel around to each one of you guys providing guidance, sharing information that way, doing instead of saying. You need practical experience and actual references to what's being said and that is severely lacking in many of these conversations. Many of you don't have a true reference for live un-amplified performances or frequencies in general and it comes through in your questions and suggestions. I'm not attacking anyone, please understand that. Just had a thought and wanted to give a perspective. Setting up front stage is actually very easy, but without references and practical experience, discussing it makes it seem arduous. What's needed is a true understanding of exactly what frequencies affect different instruments and voices and such, but also excursion and power handling relative to those frequencies. Add to that, power response (on and off axis), filter poles (shallow to steep), phase and time coherency (probably four or five people on this site who even understand the true principal behind this), end goals (SPL or realism), etc... it's no wonder we misinterpret and misinform. Myself included!

Random rant, food for thought, what have you...


neo, that sig is hilarious.

calebkhill
02-09-2013, 01:11 PM
One thing that's frustrating about forums is that information sharing only goes so far and interpretation ruins a lot of it. I wish I could travel around to each one of you guys providing guidance, sharing information that way, doing instead of saying. You need practical experience and actual references to what's being said and that is severely lacking in many of these conversations. Many of you don't have a true reference for live un-amplified performances or frequencies in general and it comes through in your questions and suggestions. I'm not attacking anyone, please understand that. Just had a thought and wanted to give a perspective. Setting up front stage is actually very easy, but without references and practical experience, discussing it makes it seem arduous. What's needed is a true understanding of exactly what frequencies affect different instruments and voices and such, but also excursion and power handling relative to those frequencies. Add to that, power response (on and off axis), filter poles (shallow to steep), phase and time coherency (probably four or five people on this site who even understand the true principal behind this), end goals (SPL or realism), etc... it's no wonder we misinterpret and misinform. Myself included!

Random rant, food for thought, what have you...


neo, that sig is hilarious.

Experience does go along way. Thanks for that.

calebkhill
02-10-2013, 01:25 AM
Well you're sensing the difference when you move your leg because that full range signal is trying to bounce around your leg. Upgrading to components and placing them either in the sail panels or (ideally) at least 2" above the dash should help dramatically with that.
I understand this. I feel I need to raise more of the sound above the legs because everything under 3.5khz is getting blocked.
And when you say components above the dash 2", you do mean the tweeters right. Also, are 2"and 3" full range drivers interchangeable with tweets. All seem to have the same frequency response. Reason I ask is if I don't go three way, a 3"and 6.5" driver seems like it could cover a larger frequency range and you could be a little more flexible with crossover points to get more efficienct response from your drivers. Get what I'm saying?

neo_styles
02-10-2013, 01:55 AM
I understand this. I feel I need to raise more of the sound above the legs because everything under 3.5khz is getting blocked.
And when you say components above the dash 2", you do mean the tweeters right. Also, are 2"and 3" full range drivers interchangeable with tweets. All seem to have the same frequency response. Reason I ask is if I don't go three way, a 3"and 6.5" driver seems like it could cover a larger frequency range and you could be a little more flexible with crossover points to get more efficienct response from your drivers. Get what I'm saying?

There have been quite a few SQ setups that used a wideband 3 or 4-inch, dedicated midbass, and no tweet. Just plan to spend a lot of time either dialing in your crossover frequencies or EQ-ing all the boosts caused by overlapping if you do go with a midrange. The one flaw of a lot of midranges, some say, is the fact that while they extend high into the range, it's not up past the 12-16k range where things can sometimes lose their "sparkle." Honestly, I think it's subjective and if you want to go wideband midrange instead of tweet, knock yourself out.

As far as the stuff disappearing behind your knee comment, TA will help to a certain extent, but won't be a cure-all.

And for the 2" above the dash, yes, I meant the tweeters. Ideally, they should go in spheres and at least 2" above the tallest point on the dash with a dash mat covering all the smooth surfaces to minimize reflections.

calebkhill
02-10-2013, 04:20 AM
There have been quite a few SQ setups that used a wideband 3 or 4-inch, dedicated midbass, and no tweet. Just plan to spend a lot of time either dialing in your crossover frequencies or EQ-ing all the boosts caused by overlapping if you do go with a midrange. The one flaw of a lot of midranges, some say, is the fact that while they extend high into the range, it's not up past the 12-16k range where things can sometimes lose their "sparkle." Honestly, I think it's subjective and if you want to go wideband midrange instead of tweet, knock yourself out.

As far as the stuff disappearing behind your knee comment, TA will help to a certain extent, but won't be a cure-all.

And for the 2" above the dash, yes, I meant the tweeters. Ideally, they should go in spheres and at least 2" above the tallest point on the dash with a dash mat covering all the smooth surfaces to minimize reflections.

I see. You say some say, you have any experience with 2" and 3" drivers? I definitely don't want to loose tweet. My goal is to have the whole frequency range playing as detailed as possible. I thought if doin a two way set up I could use a 3" so I could band pass the 6.5s a little lower.
So let me ask, how high into the range does a 6.5 start to break down. It seems like they play frequencies up to about 2.5 great, id like to cut them off somewhere around there. maybe run a 3" 2.5-4k, tweet 4K ->
Maybe I'm wrong I haven't had time to research lately.

Edit: Also I figure going 3 way I could place the smaller drivers higher up to bring more frequencies above the legs which would mean raising the stage right? Also, when I ask about using a 2" or 3" in place of a tweeter I'm thinking I could bring more frequencies higher up in a2 way setup.

neo_styles
02-10-2013, 12:58 PM
I see. You say some say, you have any experience with 2" and 3" drivers? I definitely don't want to loose tweet. My goal is to have the whole frequency range playing as detailed as possible. I thought if doin a two way set up I could use a 3" so I could band pass the 6.5s a little lower.
So let me ask, how high into the range does a 6.5 start to break down. It seems like they play frequencies up to about 2.5 great, id like to cut them off somewhere around there. maybe run a 3" 2.5-4k, tweet 4K ->
Maybe I'm wrong I haven't had time to research lately.

Edit: Also I figure going 3 way I could place the smaller drivers higher up to bring more frequencies above the legs which would mean raising the stage right? Also, when I ask about using a 2" or 3" in place of a tweeter I'm thinking I could bring more frequencies higher up in a2 way setup.

Yeah, never run wideband mids in my car but I have seen it done successfully on quite a few cars. Some have just taken the round vents in their cars and popped the widebands in there to get them on-axis and it worked great.

Every 6.5" is built differently, but a lot of the consumer models tend to break up once you pass the 2-2.5k region. Some, like the EAD models, don't break up until well past 8k, but the price reflects it.

If you're planning to use a wideband mid in a 3-way setup, it might be a real smart idea to have someone make some fiberglass pods for your mids and tweets and put them on the dash in between the a-pillar and the windshield (in that deep corner). It keeps it easy to align the drivers to not only be as close to on-axis as possible, but makes TA and EQ much easier. Just keep in mind the 80prs is meant for 2-way front stage plus sub, so you have to be creative with making a sub work with the 80prs.

calebkhill
02-11-2013, 06:24 PM
Yeah, never run wideband mids in my car but I have seen it done successfully on quite a few cars. Some have just taken the round vents in their cars and popped the widebands in there to get them on-axis and it worked great.

Every 6.5" is built differently, but a lot of the consumer models tend to break up once you pass the 2-2.5k region. Some, like the EAD models, don't break up until well past 8k, but the price reflects it.

If you're planning to use a wideband mid in a 3-way setup, it might be a real smart idea to have someone make some fiberglass pods for your mids and tweets and put them on the dash in between the a-pillar and the windshield (in that deep corner). It keeps it easy to align the drivers to not only be as close to on-axis as possible, but makes TA and EQ much easier. Just keep in mind the 80prs is meant for 2-way front stage plus sub, so you have to be creative with making a sub work with the 80prs.

I don't have the 80prs. But I should be able to get everything right. I'll run my tweets and mids off the front pre outs and run the front and rear off the rear pre outs and use crossovers and gains to control the levels. I'll do ta later on.
I well eventually get fiberglass molds done for the a pillars. Id like to do them myself, but do you know someone who does them?
I'm going to have to figure out how to solve the "legs" situation though, this is going to be a major problem.

sjv13
02-11-2013, 06:33 PM
ciaonzo; neo_styles;

could someone explain to me what on/off axis means?

neo_styles
02-11-2013, 06:48 PM
ciaonzo; neo_styles;

could someone explain to me what on/off axis means?

On axis just means the speaker is pointed at your head or as close as possible. Most tweeters/drivers perform best directly on axis and start to wane in wide-range FR the further off axis they go. Here's an example using the FR curve of the Vifa XT-25 ring radiator tweeter(courtesy of Madisound):

http://www.madisoundspeakerstore.com/images/products/xt25bg60/XT25BG60-04-freq.png

Axis response is color-coded, so the black line is directly on-axis, purple is 15 degrees off axis, and red is 30 or 45 degrees off axis. Obviously the more off axis you get, the more attenuated the upper range will be even though they all play consistenly until about 2K.

sjv13
02-11-2013, 06:55 PM
On axis just means the speaker is pointed at your head or as close as possible. Most tweeters/drivers perform best directly on axis and start to wane in wide-range FR the further off axis they go. Here's an example using the FR curve of the Vifa XT-25 ring radiator tweeter(courtesy of Madisound):

http://www.madisoundspeakerstore.com/images/products/xt25bg60/XT25BG60-04-freq.png

Axis response is color-coded, so the black line is directly on-axis, purple is 15 degrees off axis, and red is 30 or 45 degrees off axis. Obviously the more off axis you get, the more attenuated the upper range will be even though they all play consistenly until about 2K.

Ok. Thanks. So since my tweeters bounce off my windshield they'd be considered 90 degrees off axis? Or is it different when bouncing the sound is the idea in the first place?

neo_styles
02-11-2013, 07:00 PM
Ok. Thanks. So since my tweeters bounce off my windshield they'd be considered 90 degrees off axis? Or is it different when bouncing the sound is the idea in the first place?

Bouncing off the windshield is a different beast, entirely. To make things easy, it would be more of an on-axis setup, but I wouldn't recommend doing that since reflections are pretty much the source for all that sibilance and harshness we try to remove from our tweeters. If your new speakers come with an angle-mount cup, that'll mitigate a bunch of reflection issues. If you want to go hardcore, invest in a dashmat as well. The difference is pretty remarkable.

sjv13
02-11-2013, 07:02 PM
Bouncing off the windshield is a different beast, entirely. To make things easy, it would be more of an on-axis setup, but I wouldn't recommend doing that since reflections are pretty much the source for all that sibilance and harshness we try to remove from our tweeters. If your new speakers come with an angle-mount cup, that'll mitigate a bunch of reflection issues. If you want to go hardcore, invest in a dashmat as well. The difference is pretty remarkable.

Interesting. My tweeters are just in the stock location. What's a dashmat? How much are they? And where do I buy one?

neo_styles
02-11-2013, 07:05 PM
DashMat | America's #1 Dashboard Covers (http://www.dashmat.com/)

Price depends on your vehicle. I got a 40-dollar quote for my Passat, so they're really a low expense. Yeah, it looks weird driving with a dashmat like your grandpappy would, but it should be high up on the list for deadening treatments for any SQ nerd.

calebkhill
02-11-2013, 07:18 PM
Bouncing off the windshield is a different beast, entirely. To make things easy, it would be more of an on-axis setup, but I wouldn't recommend doing that since reflections are pretty much the source for all that sibilance and harshness we try to remove from our tweeters. If your new speakers come with an angle-mount cup, that'll mitigate a bunch of reflection issues. If you want to go hardcore, invest in a dashmat as well. The difference is pretty remarkable.


Mine are in the dash too and I had harshness. But I found that ALOT of attenuation and scooting back about 6" cleared it up. They sound great now

Edit: Setting the levels properly on the door speakers helped too.

calebkhill
02-11-2013, 09:26 PM
excursion and power handling relative to those frequencies. Add to that, power response (on and off axis), filter poles (shallow to steep), phase and time coherency
ciaonzo; Would you mind explaining these concepts? Or post a few links? Would like to read up on some of this. Especially how excursion and power handling are related to frequencies, I'm not sure if I completely understand what your saying here.