SQ Steps

MacLeod

18 db is the steepest slope youve got for your sub cutoff? Thats a little odd.

I thought you were using a Pioneer head unit with a bunch of EQ features or am I thinking of somebody else?

18 is a little shallow for a sub. You can always set the cutoff point lower like say 40 Hz and then EQ 80-200 down as far as theyll go on the EQ.

arun1963

hi mac,

HU is pioneer premier p80prs. This is a model made and sold in Asia. Looks and features are identical to 800PRS as sold stateside. Infact the service booklet in the box is also for 880prs. The only difference between the p80 and p880 is the extra options on slope adjustment. Why they would keep this difference, I dont know. There is an upgraded version called the p80prs2 on which you can do slopes upto 36db/oct. :mad: Amazing how you discover these facts after you have spent the $$$$.

I have been building the system for the last 14 months and here is a list of the equipment purchsed and now redundant;

MM 691 - 1 pair, used for 4 months - purchse price $ 245
HU Pioneer DEH P 7200 - Used for 8 months - purchase price $ 260
Kenwood 4ch amp 4x60 watts rms - used for 6 months - purchase $ 280
Polk Db 651 1 pair - used for 6 months as fronts - purchse $ 120
To be added to this list as and when I upgrade my sub setup:
Polk PA 400.1 - used 6-8 months - purchse $ 325
Polk momo 2124 sub - purchse $ 250

Momo components will never be redundant. Even when I finally upgrade to SR comps (as I will one day and therefore have to remove the momo's), I will always value and keep my momo comps. The momo comps have been my gateway to SQ.

That is $ 905 worth of equipment that is currently redundant and $ 1,480 will be redundant once I upgrade my sub setup. If I had bought wisely I would have had an all SR setup AND some spare $$$ in the bank. :mad::mad::mad:


So far this is the only downside of the SQ chase. However by nature I look at the glass as half full. Hence only looking at the benefits.

For all who read this thread in INDIA, I am bsed in New Delhi and above mentioned equipmennt for sale. Will offer a great package price, or will also sell piece meal. Most of the stuff is still under waranty.

sgesang

Where can I find the spec. of the new p80prs2???

cadenceclipse

36db slopes sound nice, eh?

arun1963

Where can I find the spec. of the new p80prs2???

Go to the Pioneer sinagapore web site. The model is DEH-P80RSII. You can download the manual from there. Available in the grey market (no warranty) in India for around Rs. 22-25K.

http://www.pioneer.com.sg

36db slopes sound nice, eh?

You bet. However priority right now is to focus on and spend time and $$ on the sub setup.

cadenceclipse

Rs. 22-25k, whats that, rubies?

forgot, arun, r u saving for an sr or something?

heres an idea, use lpf on amp, fixed at 24db? +18db from hu =42db, booyah! :eek: :rolleyes: :cool:

cadenceclipse

63Hz, 42db slope im using 48db slope at 80Hz

arun1963

Rs. 22-25k, whats that, rubies?

forgot, arun, r u saving for an sr or something?

....close. Rupees.

heres an idea, use lpf on amp, fixed at 24db? +18db from hu =42db, booyah!

Would it work?

Engaging lpf from the amp would feed only frequencies below the dialed in frequency to the xover. Signal path is HU to Amp to xover to spkr.

Hence, if HPF for mids set at 63hz at hu and lpf selected at amp set to 250hz (max), the xover would feed frequencies below 250 to the speaker.......

cadenceclipse

so you have an on/off switch on your amp? your amps max is 250hz?

cadenceclipse

i know some guys on here don't like using 2 seperate active crossovers but i figure steeper slopes, why not? to be honest i like to believe i let my ear do the talking and i seem to have more control in a positive way

MacLeod

cadenceclipse wrote: »

36db slopes sound nice, eh?

For mids and highs, you dont need anything more than 24 db. Subs are a different story. Id have a 100 db slope if I could.

cadenceclipse

care to comment on the "2 source xover" issue mac? you don't need anything more than 24db on your subs also, no? but why not, eh? how many dbs you using on your subs mac? btw, u a truck driver?

MacLeod

Yeah you need more than 24 on your subs if youre going to precise imaging. The sub begins to locate a little passed 50 Hz. Id prefer to have my sub cut off at 50 and maybe even 63 but I cant get any higher than 40 before 80 and 100 Hz make themselves known. Even tho theyre at a low volume its still enough to locate the sub.

If youre not going for 100% perfect "up front bass" imaging then 24 db would be plenty. My "daily driver" setting is 63 Hz @ 24 db/octave. My competition setting is 40 Hz @ 30db/octave with 50-160 Hz down -9 on the EQ.

I ran over the road for a few months and hated it so now I drive a beer truck.

cadenceclipse

thats what i mean, u use 24. where do u get the extra 6 from? using amp xover or that alpine processor? why not use steeper slope, you have it on hand right? your last post had nothing to do w/ highs right, only subs?
damn, 40hz at 30db. what about 2 source active crossover

MacLeod

Dont care for 2 source crossovers which is actually called cascading crossovers.

No real logical reason behind it really, Im just a huge believer that the fewer components you use, the better and the less likely youre going to screw something up. So I prefer to keep anything that is affecting the signal to be under one control - my beloved and trusty H700.

arun1963

so you have an on/off switch on your amp? your amps max is 250hz?

Yes I can either run all four channels or only the rears. Sorry max is 500hz for the xover point dial on the amp. If this went upto 3khz then your idea would work.

To my mind, its important to control the actual frequency range that each speaker is getting, both from a tuning and blending standpoint. Hence ideally I want my mids to play 40hz to 3.5-4khz, my tweets to play 3.5-4kz upwards and my sub to play subsonic-63hz. This I feel would be nice. if I could acchieve this then, 40-63hz and 3-4khz would be blending zones. Against this what I'm actually getting is;

Sub ; 15 to 90hz (lpf 63hz @18db from hu + lpf 30hz @ 18db from mono amp, subsonic filter off)

Mids ; 40-4khz
Mid HPF from HU at 63hz @ 12db hence amp is getting frequencies till 40, using hpf at amp with xover dial set to min(50hz at amps internal slope of 12db). Hence xover connected to mid speakers are getting low of 40@24db. Passive crossover cuts off high freq at 2.6khz at xovers internal slope of 12db. Hence mid speaker is getting 40 to 3.5-4khz. Thats what logic tells me.

Tweets : 2.6khz upwards

Hence while tuning I have to watch ("hear &tune") the following blending frequencies very carefully;

sub to mid : 40-100hz. In my opinon this is too big a blending range to control accurately. I am constantly struggling to get it right and its a **** to set properly. Steeper slopes would narrow this band. Ideal band for blending would be 40-63hz. This is my assumption.

Mid to tweets : 2-4khz, this is a narrower range than sub to mid and hence easier to blend. It would be nice to have active xover here where the mids would play till 4khz and the tweets would kick in at 4khz. Will be able to do this once get a 24-31band equaliser with an active xover.

Mac, is my logic above correct?

sgesang

Arun,

Quick question for ya. what do you mean by "box-in" in TA?? Do you mean the sound stage is all around you but not coming from windshield?

arun1963

hi sgesang,

At that point of time, the soundstage was narrow. About the width of my body. If I closed my eyes and listened, it felt like the vocalist was like 6" from my face. Hence boxed in. The sound was coming from the front, but I felt cramped.

I now know this was happening for two reasons.

1. The stage wasnt high enough. Mac had mentioned that while time aligning, the sub sould always be at 0 / actual distance and everything else should be time delayed.

To lift the stage, you have to delay the mids a fair bit from their actual distance, but your far side mid cannot be further than your sub (Time aligning in inches ) At that point my sub was deeper in the boot, at a distance of 66 inches. Hence I could not take my far side mid beyond say 58". Actual distance to far mid is 49". I struggled with that for a while and then realised how stupid I was (yes again ). My sub is in a box with a longish connection to the amp. Opened the boot and moved the sub 15" back towards the boot lid. Now physical distance of sub was 75" and I could set the left (far side) mid to 72". 23" more than its actual distance. That brought the stage up.

2. The tweeters need to be further out than the mids (and from thier actual distance). The greater the delay you can add between the mids and tweeters greater the height of the stage. It opens the sound nicely. The catch here is that the far side tweet cannot be set at a greater distance than the near mid. Otherwise you will hear the far side tweeter before the near side mid. Currently my near side mid is set at 57" (actual distance 32") and my far tweet is set at 53" (actual 45"). You should first hear the sub, then the mids together and then the tweets together. Another nugget from Mac. The mids and tweets also need to align vertically on the wind shield, with the tweets higher.

Come to think of it, I wrote the above not knowing if you were in the same situation, or just looking to help. If the latter, sorry didnt mean to reinvent the wheel for you.

candaddy

If your tweeters are in locations very close to the mids (like in kick panels) then I do not believe delaying them like you suggest will work. That will only work if they are up high in doors, the dash, sail panels or a-pillars, etc.

I just wanted to mention that in case someone here was dealing with a different type of install and was going to try your techniques (which would not work in that different situation). If you did that in a kick panel situation, you'd actually be pulling the stage downward. Or at least that is what happened in my car with my kick panels, which is also exactly as audio theory would support.

arun1963

hi candaddy,

I honestly never thought of that. But you are right on both counts.

1. It will vary with install

2. my mids are high up on the door panels and the tweets are halfway up the front pillars. Distance between centre of mid to tweet is 18".

Another factual correction, sub was earlier at 60" not 66". 66+15 is 81 it is now at 75". Should have scanned once before posting, but it was 1 am in the morn.

arun1963

just for info, how does it work when mid and tweets are close to each other like in your case?

candaddy

The arrival time for each needs to be very close, if the tweeters are delayed too much, their presence will be more noticeable and you'll actually be pulling the sound stage downward toward the floor because that's where the speakers are! In your case, delaying the tweeters is bringing the sound stage upward because that is where the tweeters are located.

The process for setting the delay would actually be the same as Mcleod suggested earlier, just that your actual settings would not be the same as they are now.

What you are doing when you alter this facet of your settings, is effecting the lobing of the speakers. Speakers mounted down low need to have very good coherency at the crossover frequencies or the two (tweeter and mid woofer) will each be fighting for your brains attention and that makes the sound stage drop to where ever the speakers are mounted.

With my Momo's, I had no time alignment, but I physically placed them at exact measured distances. In fact, I had to actually move the tweeter after the first try because it still was not far enough away on each side to measure identically with the Mids. Once I got the physical time alignment correct, the sound stage rose right up like it should. I EQ'd it for left and right + some minor flattening of the response and was very happy with the sound. My tweeters were literally about 3" off the floor and highs like cymbals were always dead center at eye level, it even surprised me.

At lower volumes, I did sometimes have a slight "rainbow" effect, but not at realistic listening levels.

cadenceclipse

can u please explain "good coherency at crossover frequencies" candaddy?

candaddy

That statement just means that each speaker is playing in phase with the other, or at least that's what I meant by it.

I'll see if I can dig up some links that will give you guys some good reading on the subject.

arun1963

Running a momo 12" sub at 2ohms of the polk pa 400.1.

I know the sub is underpowered. I was running the sub in a 1.3cuft ported encl. For a short while I went to a sealed enclosure, but it was of the wrong size and the mdf used was not thick enough so there were reverbration issues.

So went back to my old ported enclosure. I decided to try another vendor for a sealed enclosure, gave him the specs, 0.88 cu ft and 3/4" mdf heavy board. Today I went to get it installed. Upon measuring the box it turns out to be 1.2cuft. :mad:

The guy offered to fix it by pasting some thermacol behind the driver to reduce the box volume. He installed it with the rider that if I didnt like it I could return it. Here's the problem:

The overall bass is much tighter. The sub is cut off at 50hz and the mids at 63. Frequencies from 50-125 are much clearer and lifelike, but the bottom end is gone. Its there at very loud volume but drops off at listening volume.

Questions:

1. Is the damn thermacol killing the bottom end frequencies? I.E. take out the thermacol and use this box even though its bigger than required?

2. Should I go back to the ported box.

I want to be a glutton. I want the mid bass clarity and power that the sealed box gives and the bottom end of the ported box. Tmrw is sunday and I dont want to waste half the day at the shop experimenting.......

arun1963

a ton of thanks in advance. Feel really silly being in this situation

MacLeod

This guy doesnt sound like a professional. "Hey I screwed up your box but rather than building a new one to the spec's I promised you Ill just stick some duct tape on it and youll be fine."

The box is too big and while youve got a much flatter response, youre used to the response hump at around 40 Hz or so (a guess) from the ported box. This bigger box is giving you a flatter response which is great if youve got plenty of power and an EQ for the sub. If you dont and just want the bass back, youre probably gonna have to get a .88 box.

Most shops should have a pre-made box that size in inventory. You should check some local car audio shops for them. Have you considered building the box yourself? Its as easy as cutting out the wood and **** it together. A little TLC is all youll need and about $30 in wood and supplies.

arun1963

"This guy doesnt sound like a professional. "

Thats the way audio retail is over here. Partly becoz 99.99% of the people here would not know the difference. Spl sells big here.

The box is too big and while youve got a much flatter response, youre used to the response hump at around 40 Hz or so (a guess) from the ported box. This bigger box is giving you a flatter response which is great if youve got plenty of power and an EQ for the sub. If you dont and just want the bass back, youre probably gonna have to get a .88 box.

yes, ure spot on. With the ported encl I ran 50hz at -4/-2 L & R, anything more and the sub was located and sound got boomy. I can now run 50hz at -2/-1. This gives 'life' to 80-200hz. But that punch you mentioned at 40 hz is gone.

The sub bass presentation is much better. Earlier, the sub bass would be up front but down at my knees. I could feel / see it rushing upfront, down the centre of the car. Now, whatever there is, comes from the top of the dash, Thats new for me. but it doesnt hit me in the chest.

Extra power would have helped for sure. However, for now it its cheaper to buy a smaller box than to get a bigger amp Will get a bigger amp and sr sub when I upgrade my speakers.

To minimize costs, following a simple philosophy. "Till the time the speakers show the limitations of the set up, upgrade the setup. When vice-versa, upgrade speakers..."

Found a 0.75 box at the shop. Will stuff this with a bit of dacron and the driver should see a 0.83 box. Major waiting time today (being a sunday) so will get this done mid week.

Have you considered building the box yourself?

Mac, u know how prone I am to the FMS (Foot in the Mouth Syndrome), well my hands are clumsier than my mouth lol.......:o

tks a ton, as usual, great root cause analysis from yr end.

arun1963

The sub is in a 0.9 sealed enclosure since this past Thursday.

There is a big difference between the sub bass presentation from a ported and sealed enclosure. That and the way it impacts the rest of the sound.

With a ported sub there is a lot more bass to tune around......but the results aren't as precise. While no single driver grabs your attention, at various points in a song, you can locate individual drivers. You feel the bass upfront and it kicks, but its presentation is not from directly in front. Its kind of wallowing at my knee level. This sub bass impacts a fair bit on the 60-200hz range. It makes these frequencies a lot heavier. The sound can get boomy very quickly. You have to pull back a fair bit on the 20-50hz range, with level balancing since the left side is hotter for these frequencies.

With a sealed encl, the sub bass has to be fleshed out. The mids need to be be in perfect sync with each other, leveled and blended well with the sub. I could not achieve this accuracy with the ported. I could never get staging / imaging to where I wanted. With the sealed I got to where I wanted only to discover that discord in the frequencies I can't control is audible.

Thats a small price to pay for the gain everywhere else. Once its all dialed in, the sub bass is focused and from the front vs just upfront with the ported.

With the sub cutoff at 50hz, I now run 20hz, 31.5 & 50 flat. I could never do that with the ported. The sealed box gives less bass overall, but what's there is much tighter and more focused. In my case, if I'm still missing a bit of the punch, its more to do with the fact that I'm under feeding the 12" momo sub with a pa 400.1.

The mids are tighter too. I can set the mids with much higher accuracy with a sealed box. About 5 mts after I hit this point, I realised that something was different. Something about the presentation. Then it struck me. I could no longer hear my speakers. I couldn't locate them. Everything was 'from the front'.

arun1963

Above was a bit of a long winded explanation for the issue I need help with. This ported vs sealed thing was supposed to be bit of a side step but it has turned into a lot more.

Have been saving to buy the RF 3sixty.2 as an upgrade to the setup. I would be ready to drop the cash next month.

I really want to seperate my mids and tweets via an active xover. If I can hear the impact of tweaking 12.5khz while listening only to the mids, I know I have to seperate the two to achieve better harmony. That and I would like to really focus the staging / imaging by controlling more frequencies.

I would also like more at the low end, for which I need a bigger amp. If I upgraded the mono amp I would either go for the polk 1200.1 or the alpine pdx 1.1000. The pdx apart from having a great birth sheet has great sex appeal. Love at first sight.

The pdx and the 3sixty are about the same price here ($ 800), the 1200.1 is a bit cheaper. So should I go the mono amp upgrade route or go for the 3sixty? The upgrade after this one would be a year down the line.