[DerAlte]

Originally Posted by nura

S... Now hear a faint scratching sound ...

Any ceramic-coated unipolar value less than 1uF (1 microfarad) will do. Across the terminals of each horn. Should be available with any electronics technician - look for a voltage value of ~400V.

Probably due to the power cables *and* the horns being on the left side of the car.

[nura]

Clear, thanks. Will try to procure & install the caps over the weekend & report.

[nura]

Never was satisfied with the loudness of my IDQ12D2V2 sub wired to show 4 ohms to the Audison LRX1.400 delivering 350W at this impedance. Wondering if any of the following options will help improve matters.
1. Wire the voice coils to show 1 ohm & get the amp to deliver 900W. Seem to remember reading somewhere that this will not increase loudness at all! True or false?
2. Put some polyfill in the sealed box
3. Vent/port existing box or get new if larger needed
4. Get a bandpass box made
Only if none of this works, maybe get a class D amp that puts out true 500W or more at 4 ohms. Any suggestions?
Thanks in advance for your help.

[DerAlte]

Originally Posted by nura

Never was satisfied with the loudness of my IDQ12D2V2 sub wired to show 4 ohms to the Audison LRX1.400 delivering 350W at this impedance. ...

Not satisfied with the loudness of that combination??? What kind of music do you listen to? This combination in a Santro will drive a normal person insane if playing hip-hop, rap, R&B, rock etc.

Perhaps it is not the combination that is the problem, but something else? Could be many reasons like gain setting, signal strength (e.g. old Hindi songs have acoustic cello bass, which is always low), etc.

[nura]

Thank you for your reply.
I listen to Dave Mathews, Chris Rea, Eric Clapton, Doors, Rolling Stones, Jack Johnson, Dire Straits, James Taylor, U2, Pink Floyd, CCR etc. Some of it is fairly rich in bass. In fact the 6.5 inchers in front do a pretty decent job of reproducing most of it. It’s the sub that’s not pitching in.
I’ve tried fooling around with the cut-offs & gain settings without much success. The mono amp gain is set about 75% of the way up. Now if I reduce the gain on the other amp to near minimum, increase the sub level at the HU 75% of the way up & also increase the volume level at the HU to about 20 or so, the sub does join in. But surely this couldn’t be the right way to do it.
I guess the small-sized, sealed enclosure is really reducing the sensitivity of the sub. Getting a new ported/bandpass enclosure should be substantially cheaper than getting a more powerful amp.
I have the Thiele Small parameters & enclosure recommendations of the sub & can scan the sheet & send it as an attachment if it will be useful & if it’s permitted on the forum.
Thanks for your patience & help.

[DerAlte]

Post them here, so that the Gurus can look at it.

The same music that I hear - though I also listen to Blues, Hindi, Tamil, Arabic, whatever sounds like good music to me. I am surprised. In my Safari, I have a Infinity Kappa 12" sub in a small box with a lot of stuffing (the small box itself was too big for it, so I stuffed in an old pillow). This is driven by a Class D Alpine (it is a 5-channel one) which can only push 150W rms max into the sub. The gain is set at ~50% (connected to a Kenwood x994 with a separate sub output).

I usually keep the volume at 19 (50 max IIRC), which plays most songs loud enough for an old man. For some of the recordings, especially CD rips, I need to take it to 23. At 30 it is unbearably loud (reserved for phadakta hua item numbers ) - I have to roll the windows down, and the neighborhood knows I am there. I don't tune my system with max power in mind, knowing I will never go there. Instead, it is tuned so that I hear / feel bass even when the volume is at 13 (need to do that when there are passengers, especially ladies). At 19 the bass is as it should be - proportional. At 23, it is the same - proportional. And it goes really low.

The ID sub is not much different from the Infinity Kappa in capability. There must be some mismatch that you are not getting what I am getting. But first before you change anything: if you have a lot of stuffing in the box, try removing some to see if it goes louder (without getting boomy). And possibly try tuning the system again.

[nura]

Thanks again.
Will post the t/s parameters & box specs tomorrow.
Before I got the mono amp, the sub was connected to my other amp (5-channel), which was giving it 160W & the sub wasn't playing at all. A technician at the Blaupunkt showroom disconnected the ID sub from the amp & connected a Blau bandpass sub to the 5-channel & that nearly blew the Santro apart with loudness. With the present amp the sub is producing some sound at least. This makes me suspect that still more power is needed.
There is no polyfill in the box.

[nura]

I have attached the T/S parameters & box specifications.

[nura]

What is polyfill in Hindi or Bengali & how much would a kilo cost?
TIA.

[navin]

Originally Posted by nura

An update.
Tweeter voice coil replacement charges, if you must ask, eighty rupees!

Superb. Mumbai used to have a few of these guys around but cost of,real estate has pushed them out.

Originally Posted by nura

Thank you for your reply.
I guess the small-sized, sealed enclosure is really reducing the sensitivity of the sub.

Originally Posted by nura

I have attached the T/S parameters & box specifications.

As you can see, there is good 5 db difference in the ported and sealed box sensitivity. However with 300+ watts on tap I wonder why that is an issue. Even with an in-car sensitivity of say 90db/1w you should/will get 108-110db at 50hz before the excursion limits of the subwoofer's suspension hit their max. Do you notice any distortion as you turn the volume up? If so maybe a high pass filter at 25Hz would help.

[DerAlte]

Originally Posted by nura

What is polyfill in Hindi or Bengali & how much would a kilo cost?
TIA.

There is no direct equivalent. Ask for 'polyester cushion/pillow stuffing' or 'polywool'. If the local shops don't understand it, pick up a cheap pillow (one can no longer make cheap pillows with cotton) from Big Bazar or a supermarket like that for 200. No idea how much that weighs. but half that pillow will suffice for damping.

[navin]

Originally Posted by DerAlte

There is no direct equivalent. Ask for 'polyester cushion/pillow stuffing' or 'polywool'. If the local shops don't understand it, pick up a cheap pillow (one can no longer make cheap pillows with cotton) from Big Bazar or a supermarket like that for 200. No idea how much that weighs. but half that pillow will suffice for damping.

Typically you can use Dacron which Reliance uses for their pillows. About a pound per cu. ft. Is more than enough. I start with half a pound per cu. ft. and add by ear. However one word of caution. Polyfill is not last word in damping. When I make speaker cabinets (that is a separate topic) I use a mix of damping mat like dynamat (a TBHPian called Monty has made a local substitute), open cell foam and polyfill. The dynamat and open cell foam is used on the cabinet walls and the polyfill is used only when the cabinet is sealed (not ported) but only on the bracing. Too much damping can rob the speaker of it's life so be careful.

[nura]

Thank you for your very helpful replies. Is spray glue available in India? Was thinking of sticking the polyfill to the floor & sidewalls of the enclosure to avoid potential damage to the driver.

[nura]

Adding polyfill, unfortunately, didn't help.
The Missus got half a kilo of Dacron for 75 bucks from Chandni Chowk. Stuffed about half of it into the sub box but it's sounding the same. Quite frankly wasn't expecting it to sound much louder. Am posting some pictures.
An audio dealer showed me a brochure for the JBL GTO 14001 amp. 1 x 1200W @ 4 Ohms. List price 35K. Asked him if he could arrange a demo. He called up someone & then started talking about a Cadence Dakota. Checked out the net - the Dakota is only 400W.
The GTO 14001 is not on JBL's website. Is it unavailable?
TIA.

[nura]

Checked the resistance of the sub with a DIMM across the binding posts & it showed 6.3 Ohms. Shouldn't it have been 4 Ohms?
The speaker wires from the mono amp to the sub were connected to the binding posts when I measured. Could this have caused the higher reading?
The Rockford Fosgate distributor has a man in Kolkata. The 700Wx1@4Ohm amp costs 66K & the 1500x1@4Ohm amp 125K. Crazy.
Am planning to demo a JBL GT5-1204BP sub, if it's available here. If it plays well, I might just replace the ID sub with it & cut my losses.
Any advice from the gurus re this JBL sub?
TIA.