[kpkeerthi]

A pretty old setup though, done by a Radio Ware House (Chennai) person. The install was pretty neat. No dangling wires, loose connections etc. Tuning was pathetic though. I used to be a loud hiss when the music is not playing and subwoofer sounded totally off - too much bass shadowing the fronts and the rear ovals.

Here goes my bold attempt to tweak the setup and set it right.

My Setup:

1. Front - a pair of 4" coaxials (JBL P452)
2. Rear - a pair of 6 x 9 ovals (JBL GTO937)
3. A 4 channel amp (Profile 1040), channel 1 & 2 driving the front and channel 3 & 4 driving the rear
4. HU (Sony MEX-BT5700U)
5. (Subwoofer - JBL GTO 300.1 powering a JBL 8" tube) => Currently offline/turned off

Amp Settings (current):

Channel 1 & 2: HPF/LPF = Off (Pass through)
Channel 3 & 4: HPF/LPF = Off (Pass through)
Gain: 50% (for both the channel sets)
Bass boost: 0%
Trebble boost: 0%

HU settings:

HPF Speaker set to- Front
HPF cut off is at 100Hz

With this, I have the annoying hiss eliminated. Also the clarity and crispness at the front has found a vast improvement. I'm very happy with how the front sounds at the moment.

The problem now is there is a lack of 'punch' from the rear. Sounds just plain flat. Please note that sub-woofer turned off at the moment. So...

1. tried turning on LPF of Ch 3 & 4 and set it to about 80Hz - No improvement
2. tried setting the cut off at 100Hz - No improvement

What can be done to improve the sound from the rear without compromising on clarity? I could really use some help here. Sorry about the long post.

[DerAlte]

How is the 300.1 connected to the HU?

1. Set LPF on Ch 3&4, and set it to 60Hz (so that when the sub is back on, it will handle anything below that). Ditto on the 300.1
2. Set the gain of all channels to 0 at the amp(s)
3. Play your favorite CD, and set HU to a comfortable volume level that you normally use
4. Bring up the gain of Ch1&2 till the fronts sound comfortable
5. Now increase the gain of Ch3&4 till the rear sound is just slightly less than the front (ignore the bass, concentrate on vocals and higher frequencies)
6. Fade front and then rear to confirm you can hear the image shift forward and backward properly
7. Now, increase gain on the sub amp till you get a level where if you reduce slightly you can sense bass vanished

At this time, your system is balanced. Increase the volume at the HU to check whether the sound distorts (not expected to). Now you can increase / decrease the sub to suit your liking.

[navin]

I asume the 300.1 is connected to the subwoofer outputs on the HU. Start with

LPF for subwoofer: 80Hz.
HPF for front: 100Hz
HPF for rear: 60Hz.

The overlap between 60 and 80Hz should give you a bump in the midbass and more "punch".

[kpkeerthi]

Thanks DerAlte & Navin.

Sorry, I forgot to mention that the 300.1 is connected to the subwoofer output on the HU. This is my first attempt at tuning. After some more reading and of course your posts, I kind of get the whole picture now.

As for the front, the 100Hz HPF cut-off seems to the sweet spot.

And Navin, I believe you meant 'LPF' for rear: 60Hz and not HPF. No?

[abhibh]

Originally Posted by kpkeerthi

Thanks DerAlte & Navin.

Sorry, I forgot to mention that the 300.1 is connected to the subwoofer output on the HU. This is my first attempt at tuning. After some more reading and of course your posts, I kind of get the whole picture now.

As for the front, the 100Hz HPF cut-off seems to the sweet spot.

And Navin, I believe you meant 'LPF' for rear: 60Hz and not HPF. No?

HPF the rear aka 3&4 ch to 80 hz.
LPF the sub amp 300.1 section at around 80-100 hz.

[DerAlte]

Originally Posted by kpkeerthi

... I believe you meant 'LPF' for rear: 60Hz and not HPF. No?

No. LPF passes frequencies *below* the set frequency, so if you set LPF for the rear ovals, it would only reproduce lows, but not mids and highs. HPF does the reverse, so what Navin has instructed is to limit the lows going to the rear ovals to 60Hz, since they anyway can't reproduce below that efficiently.

Also, as Navin suggested, the 60-80Hz region overlap between the ovals and the sub will give a power boost to that band - that is what you wanted.

[kpkeerthi]

Yes right. It ought to be HPF 60 Hz for the rear and I see why. Thanks for your help you both.

I just got the tuning done. I realise what I have been missing - just pure, clean, well balanced music. I'm very happy with the way the whole thing turned out. I had to do a lot a reading as I'm no ICE specialist but was a great learning experience. Just got some paint job and facelift pending before the present (Wagon R) goes to the wife.

Come tomorrow, the family is welcoming a new member, a new Ritz VDi. Can't wait to ICE it. I might go end-to-end JBL for the baby.

[navin]

Originally Posted by kpkeerthi

And Navin, I believe you meant 'LPF' for rear: 60Hz and not HPF. No?

Originally Posted by DerAlte

Also, as Navin suggested, the 60-80Hz region overlap between the ovals and the sub will give a power boost to that band - that is what you wanted.

Nope.

I think DA has explained what I meant more clearly. I am sorry if my earlier explanation was not clear.

[DerAlte]

Actually, my bad: on reading again what I typed the first time, I realize I mistyped LPF for HPF for the rear ovals. (I think I should start taking Chyawanprash Gold now ).

Anyhow, aall izz well that ends well. Good that you are enjoying the music once again.