Advice Needed from Audiophiles Here.......

[asphaltgambler]

Still working on my Targa trying to wrap some loose ends up. One of the items (on my imaginary whiteboard) is final tuning of my sound system.

Here's what I have installed:

1) Vintage NOS Mcintosh 406 Head unit
2) Vintage Mcintosh 6 channel amp (446 I think) Big, clean power
3) Dynaudio GT360 seperates w/the 170mm mid-woofer substituted (instead of the 160mm) all mounted in the front door panels
4) Kicker/mtx 10" shallow sub - front-to-rear firing w/ custom box built into pass side false floor

The amp has something close to 200w per/ch front of VERY clean power - the sub channel is bridged. Dynamat is used through out

My problem is the three ways in the door "scream" with very little mid-bass - even when dampened/accented with EQ. The supplied Dynaudio crossovers are slightly adjustable, but make very little difference. The crossovers spec is 900/4500hz

I'd like for someone here to reccomend a passive three way crossover that is mostly to fully adjustable where the quality is equal to the equipment I have so that I can tune them to my taste -

[Gogar]

Do you mean "not enough mid-bass?"

First, check to see if you wired them out of phase by mistake, never hurts to check.

It's also possible that the speaker doesn't do well with the sort of 'leaky infinite-baffle' that is your car door. You might want to try to seal up the door as best you can (pretty much impossible) or create a sealed-box behind the midbass, but that's going to be tough.

Another option is to get a 2-way active crossover and use four channels of your amp for the doors and dedicate 2 channels to midbass and 2 to the mid/high combo. You can use your passive crossover for the mid/high seperation, and you could adjust your midbass independently of the mid/his.

Then you could run the rears off of your deck power, if if has 'speaker' outs. Who cares about the rear, right?

[greglepore]

Agree that the xover of 900hz is too high for he doors-but I also agree with Gogar that you'd be better off using an active 3way xover and using separate feeds for midbass/mids and tweets. Cross over to the woofer at around 150 hz or so.

[imcarthur]

As Jeremy pointed out, car doors don't seal well. I dyna'd the whole interior door surface & most of the outer (inside the door). You might try putting some loose fill (synthetic pillow stuffing) behind each midbass & bass driver. That helped my install with lower mid articulation.

Even without the subs (dual 8" drivers in the typical rear seatwell with 600 watt mono), my door speakers (Focal *) did a reasonable job down to 80 Hz or so. Maybe the Dyns are too forward in the upper mid & highs. Try an upper cut rather than a bottom boost. Often a tilted frequency response makes you assume the opposite of the real problem.

Ian

* Disclaimer: I sell Focal home & Pro. I am biased.

[bell]

the best way to get door speakers to really have strong midbass is to make sure the panel is as "dead" as possible, dynamat works great (the cork type, not butyl rubber type) and will help separate the front/rear waves......but the more solid the panel that the speakers mount to the better the frequency response will be....same concept as if you mounted the speaker in a cardboard box......you'll lose all the lower harmonics due to resonance cancellation.....

my old dd was a nissan hardbody p/u, i had 2 pair of diamond audio 6.5's (2 in each door), dynamatted the inner door, and had the speakers mounted to a 3/4" mdf panel covered in vinyl, it was bolted to the door structure.......these were powered off a large jl audio amp with about 125watts going to each 6.5.......it sounded like i had 2 10" woofers in the truck.....never needed subs in that truck.....

[RWebb]

Originally Posted by bell

.. resonance cancellation.....

...

()



what?

[willtel]

That is a sweet list of equipment, any pics?

If at all possible you should try and run the system active but with a 3-way front stage you may need more amplification.

This is a great forum for your questions, DIYMA SQ forum - Technical & Advanced - DIYMA.com there are a few 911 owners over there.

[Eric Coffey]

As mentioned, get the mids as sealed off as much as possible (taking volume/driver "Q" into consideration) and the baffles as non-resonant as possible. Most car interiors are horrible environments for decent sound reproduction anyway. Anytime the drivers are essentially pointing at each other, 90 degrees off axis to the listener, there are bound to be sound quality/stage issues.

If you can, choose drivers with the most forgiving off-axis response. Another trick is to use baffle "wedges" to cant the door speakers a few degrees more on-axis. Or you can use kick-panel "pods". The latter is a bit harder on Targas and Cabs due to the smaller foot-wells.

A parametric EQ will help attenuate any pesky cabin/cockpit modes (nodes/antinodes). Try and find one with adjustable center-freq, range, and octave. A decent 1/3 octave (or finer resolution) graphic EQ will help a ton as well. Preferably one that can adjust L and R channels independently. If you have an RTA and mic and time on your hands, even better.

If you want the ultimate IMO, get a Behringer DEQ-2496 (and Behringer condenser mic) and convert it to 12v. That will give you individual L/R or linked control of 31 EQ bands (down to 59/3rds-octave bandwidth resolution) with parametric adjustments plus a 61 band RTA and white noise generator. You also get a host of studio processors built in as well (feedback correction, compressor/expander, digital delay, stereo separation/symmetry, etc.). I've got one for the home system, and it's a great piece of kit. The only other thing you'll have to do is make your own XLR/TRS to RCA cables if the rest of your gear is RCA. If needed, I've got a good source for those, using the best Mogami wire available/suitable for the application.

With all that said, it's best to do any "corrections" passively first (speaker placement, physical modification to the listening area, bass traps, etc.). Then tweak with parametric EQ, then lastly tweak with graphic EQ. When it doubt, trust your ears, and use EQ carefully.


Ok, enough audio geek-dom for now...

[Gogar]

Oh man Eric, I was with you until you said the B word.

[asphaltgambler]

Hey - thanks all. I could post a few pictures but for some reason my droid phone pix format remains very small when uploaded gets very fuzzy quickly when viewing standard size. I'll look for a few web pics of what I have.

To respond: All equipment is already installed. I made a custom mounting plate from 3/4" mdx to mount the door speakers - the doors have dynamat front-inside w/an outer doorskin dynamatted as well - Door panel was fiitted and complete - I am not changing anything to do w/mounting or sound deadening at this point concrning the door speakers - It was a real feat to mount 170mm mid bass and seperates to look like they came that way from the factory.

Could you guys explain / illustrate to me the wiring diagram where only 2 way cross over is used? The crossovers now are mounted under the seats

[bell]

Originally Posted by RWebb

()



what?

don't post while drinking LOL
i think you know what i was "trying" to say......if the baffle the speaker is mounted to vibrates it will in effect cause cancelations and keep the speaker from reproducing accurate sound......basically you'll get cancelations near the frequencies in the midbass range........

[asphaltgambler]

pic of the head unit / pic of the amp - by the way the amp physical size is huge 12-13" wide x @18" long x3" high

[Gogar]

Originally Posted by asphaltgambler

Could you guys explain / illustrate to me the wiring diagram where only 2 way cross over is used? The crossovers now are mounted under the seats

In my version,

You would run the FRONT RCA outs of the head unit to the ACTIVE two-way crossover (like an AudioControl or something of your choice.) The crossover has crossover point and level control for each of it's outputs.

Run the LOW outs of the crossover to two channels of the amp,
Rund the HIGH outs of the crossover to two other channels of the amp.

If your amp has a crossover built in for the SUB section then I'm assuming it is high-passing the other 4 channels also, which is good.

So, out of the crossover into the amp X4, and run a speaker out (the LOW crossover-ed one) to each MidBass,

and the other 2 channels to your passive crossovers under the seat, EXACTLY like they are already, but the Midbass portion has been removed and gone straight to the amp.

NOW, you can control the level of the midbass seperately from the mid/hi combo, either with the crossover, or the amp gain controls.

Unfortunately, this uses up two more channels of the amp, so you don't have anything for the rears, BUT if your head unit has speaker outputs, you can use them to run the rears to get some fil back there.

Sorry I think that was a little wordy.

[Gogar]

Before you do anything,

I would check the crossover controls on your amp, ESPECIALLY the "high-pass" control of your front speakers, and make sure you don't have it set too high, or have the X1,X10 switch pushed by mistake. Especially with those big mid-bass speakers, your doors should crossover pretty low, like 100, if that's as low as it will go.

I was just looking at a 406 manual here; I imagine it's similar:

http://www.mcintoshlabs.com/downloads/product_manuals/mcc406mom01.pdf

[asphaltgambler]

To be clear there are no rear speakers - just front floor mounted /rear facing sub - and the seperates in the doors - the idea being the entire sound stage is in front and sides - just like a concert experience

[Gogar]

Oh, ok.

Well, check the crossover knobs on that amp first, and then if that's not it, i'm assuming you have 2 channels open on the amp? where you could do what I suggested.

If you don't want to go to the expense of an active crossover, you could achieve the same effect with some capacitors and coils, much cheaper but less efficient.

[asphaltgambler]

thanks - I'll check the amp set-up and look into what you've suggested - Interesting note that the 406 head unit has aux input (rear) for other devices. Now that's some real forward thinking when this was designed back in the 80's

[RWebb]

bell - yup I know; that was just a joke re the cancellation effect.

On a home system, one might be concerned about time "smear" from the movement of the driver - I'd guess that in a car, the driver's head is moving around so much it's not an add'l deficit (?)

I do have a question tho - re the cork vs. butyl dynamat products you posted on: why is that?

[RANDY P]

ya, what everyone said. YOu should be aiming your midbasses for response down to 60HZ.

That'll fix your midbass , bass accuracy and imaging too. I always tuned mine that low for those reasons.

rjp

[Eric Coffey]

Originally Posted by Gogar

Oh man Eric, I was with you until you said the B word.

LOL, yeah, I know. I would whole-heartedly agree that most "B-word" gear is crap. However, the updated version of this particular unit is a diamond (or at least a CZ) in the turd-pile IMO. Just like the 1 or 2 other Behringer units that are decent (and found in plenty of pro gear-lists).

Besides, you can use it solely as a (1/6th octave) RTA/P-EQ or even as a DAC (all of which are great) without all the other crap. It's certainly a lot of bang for the buck, and is surprisingly clean/neutral in the line. Most gear-snobs are even pleasantly surprised.

Don't know what I was thinking though....with a McIntosh/Dynaudio budget, I should have recommended a TC EQ Station, or a maybe a lowly Klark Helix.

If you prefer sliding sliders or turning knobs vs. command dials, then I would opt for a decent Rane DEQ or a pair of Audio Control C-131's. If you want to kick it up a notch (and have P-EQ capability), get something like a pair of Focusrite Blue 315's, Red 2's or original (Neve) ISA 110's if you can find them. If not, look at the Neve Portico, or even the Rane PEQ55. Better Jeremy?