Hi guys

As per the title, I'm chasing a 4 channel amp, 100w rms per channel (@ 4ohm), and 300w rms bridged (@ 4ohm).

Located in the Northern Melbourne suburbs, will to drive to pick up item.

Also willing to consider interstate offers.

Let me know what you've got!

Cheers

Hi guys

My Alpine MRV-F407 (4 channel amp) appears to have developed an internal fault when playing a sub from a bridged output.

At present, my setup consists of a set of Crescendo splits feed from channels 1 & 2.
My sub (Kenwood KFC1004DB, Single voice coil, 4 ohms) is bridged from channels 3 & 4.

A few days ago while happily driving home, just listening to the radio at a moderate volume, I heard a "click" sound from the amp. The sub output volume dramatically decreased, but the splits output didn't change.

After removing and checking to see if the sub was still working, I turned my attention to the amp.

I first applied the same settings on channels 1 & 2 to channels 3 & 4, rewired the crescendo splits to be feed from channels 3/4, and listened to the output. It's the same as if the splits where powered from channels 1/2.

Next, I removed one of the splits, and bridged the output of the remaining connected split across channels 3 & 4. The output volume was far lower compared to running the splits solely off 1 channel.

I then grabbed my multimeter, and checked the resistance across the bridged terminals (which was reading around 4 ohms for the set of splits connected, so the amp is seeing the correct resistance across the output terminals). I then checked the output voltage of the bridged channel, and compared that to against the output voltage of a single channel.

The output voltage of the bridged 3/4 channels read around 1/3rd voltage (on average) of that compared to a single channel. If the single channel had an output voltage of 1V, the bridged 3/4 channel output voltage read around the 0.25-0.3V mark.

I'm not sure if this is relevant, but a few days earlier, I installed an LC6i. I discovered (after the sub output when down) that the LC6i internal grounding jumpers were set to "Isolation" mode, which produced a floating ground. The amp did detect this condition (protection light started flashing red). To be honest, I didn't notice the floating ground issue until after the sub output went down, as my system was functioning perfectly post LC6i install. No alternator noise, no turn on/off pop, nothing. For what it's worth, I've changed the jumper terminals to the "Grounded" position on the LC6i, which has cured the floating ground issue, without introducing any noise to the system.

I've removed the cover, and had a quick look at the circuit board. Noting appears to be burnt, chard, blackened ect ect. I've included some pics for reference.

Does somebody know what the problem is, and is it easily fixable? Or is this a repair that should be carried out by the Alpine people in Hallam? If it is an Alpine only repair, could somebody estimate how much it will cost?

Or am I just better off just buying a new amp?

Any help appreciated!

Cheers

Hi guys

I've recently found the Theile/small parameters for a Kenwood KFC 1004DB. They are as follows:

FS = 24.40hz
Vas = 79L
QMS = 6.446
QES = 0.462
QTS=0.431
Z = 4 ohm
Re = 3
Le = 0.9
Diaphragm diameter= 25.4cm (10 inch sub)
Xmax = 12mm
Sensitivity = 92dB/W
Driver radiating area = 350cm^2

I've plugged in the values into BassBox 6 pro. This program has recommended a sealed box. I've also completed a ported box design, as the ported design produced by BassBox 6 pro was too large. Ideally I'd like to keep the box under The 2 box properties are shown below:

Sealed box:

Box Properties
Type: Closed Box
Shape: Prism, square (optimum)
Vb =  17.86 liters
Fb =  52.82 Hz
QL =  7
F3 =  48.75 Hz
Qtc =  0.87
Fill = none

Ported box:

Type: Vented Box
Shape: Prism, square (optimum)
Vb =  35 liters
Fb =  32.14 Hz
QL =  6.6
F3 =  33.66 Hz
Fill = none
No. of Vents = 2
Vent shape = round
Vent ends = one flush
Dv =  50 mm
Lv =  300 mm

I've attached the amplitude response curves for box boxes (refer to attachment).

I'm wondering if F3 being higher than Fb is a bad thing??

If it helps, I listen to a fairly wide range of music, from rock, metal, the 60's/70's classics you hear on radio to dance. It all depends on what I'm doing and what the time is...

If the boxes are not ideal, could somebody recommend me another size?

Cheers

Hi guys.

As I don’t have access to a RTA or an Oscilloscope, I was wondering if anybody here has measured the frequency response of a BA/BF ICC unit?
If so, could they post a pic of the response, both front and rear.

I was watching a tutorial on how to setup the JL Cleansweep. The presenter showed the frequency response (via an RTA) of a few different factor units.
This got me thinking about my own unit, and the response it may produce.

There’s are quite a few Falcon drivers on here, who may at one time or another, considered using the factory unit and a LOC/DSP for their audio needs, rather than fitting a head unit.
I’ve read unconfirmed responses that the front signals are full range, but with attenduated bass  one the volume rises a certain point (how much I don’t know) while the rears are a low passed version of the front.

If anybody has got any pics of the response (front and rear) that would be fantastic, and interesting information for me and many others.

Cheers

Hi guys, novice question here!

I’ve been reading up on head units with multiple preouts (2 or 3 preouts).

I wanted to know what exactly is the sub preout signal?

From what I understand, the front left/right is a full range signal (containing all frequencies).

The same applies for the rear signals.

Does the sub signal contain only contain the lower frequencies ie 20-200hz? Is it essentially a low passed version of the rear signal?

Any help appreciated!