Thread: Project λ (Lambda) AKA Tech Van: 1994 Chevrolet G20 Conversion Van/56K WARNING!

I have been through hell and back trying to get my Kenwood KAC-8104d that I got for Christmas to work in the van. I'm on my second one. Both of the ones I've had have gone into protect mode instantly. Saul and the guy I bought it from insist it's my wiring. Well, my little Wal-Mart VR3 200W amp is powering one of my subs right now. It's SO not my wiring...

The logic negating your wiring isn't quite valid....

However, assuming the sub impedances are correct, it is difficult seeing how wiring could be to blame as wiring can only increase impededance which should not be a problem. (Correct sub-impedance meaning overall parallel/series combinations.)


Could it be a borderline case? IR - You subs are just below the threshold of the KAC but the VR3 handles it?
Or is the KAC designation telling you something? (LOL. I liked my old Kenwood.)

Surely it's not some induced hi-frequency noise being picked up by the speaker leads....?

The wiring kit that I am using: here
The Kenwood amp was rated at 1000W peak and 300 watts RMS x 1 at 4 ohms (500 watts x 1 at 2 ohms) and I had two 4-ohm SVC Kenwood KFC-W3012's wired like this:


Where right now I have my VR3 VRA2.0 amp with one of the subwoofers with 100 Watts Peak x2, and 50W RMS x2.

So I'm under-powering my sub and not powering one at all. I even called Kenwood and they told me that this guy must have got a bad batch of amplifiers. The guy I bought the amp from offered a refund or an upgrade to the KAC-8105D, but if I upgrade, I would have to cover the price difference. I'm thinking about it, then I would take it to the local shop(50 miles away ) and have them do it that way if something gets up, it's their fault, but then, what if the upgrade is a dud as well? So I could get the refund and get a new amp at the stereo shop and have them install it for the same reason, but at 3 times the cost... Either way install is $75, so either I risk another dud plus $50 or so, or get the refund (however much it's gonna be) and shell out ~$300 for an off-the-shelf amp and install... FML

And yes, I tested the subs! They are both reading ~4 ohms. 3.9 to 4.1 ohms, if you want exact readings. They are fine. It has to be my wiring or the amps. Considering a Walmart VR3 amp works, it almost has to be the amps! Else, OldSpark, give me the details, please.

Misunderstanding.
What I was trying to say is that because it works with one amp & not the other doesn't mean the wiring etc is ok.

But measure the impedance of the speakers at the amp end. It should be 2 Ohms.

And that might means that it's the VR3 that should not handle assuming its spec for 4 Ohms implies it won't handle 2 Ohms (3 sites did not show any 2 Ohm specs for it.)
Whereas the KAC should be outputting a max of 500W (RMS of course) into 2R.

Interesting indeed!
Faulty Kenwoods? Tell them the VR3 specs and that it handles the speakers.... (Or is VR3 a much classier product than Kenwood..... It sounds like it to me...(LOL!).)

BTW - parallel cranking d0.2 ok?

Originally Posted by OldSpark

BTW - parallel cranking d0.2 ok?

Ya, I got it. It looks really complicated and time consuming. I'm wondering if I wouldn't just be better off getting the isolator in "Why Did I Wait So Long" since it would be just a few wires and be able to do the same thing as all that mess?

It looks complicated because it shows the complete wiring system.

The only difference between the other isolator(s) and the relay is ONE wire that attaches to the alternator - and if that alternator has only one wire, it should not be difficult to locate.

If it's a 2 or 3 wire alternator, you need to figure out which goes to the charge lamp (which I though you had done).

It is usually far simpler than using a relay from the ignition or accessories.
That has the same "one extra wire" to, but you have to fine an accessories point (usually inside the cabin) or ignition (cabin or engine bay - eg IgCoil).

And as I said, you chose the size of "isolation switch" - 15A, 30A, 60A, 140A, 250A, 400A etc etc.
(Yes - you can add those relays to any isolation switch, but then why bother with the original expensive isolation switch in the first place? )


The complication you refer to is probably the detail others do not show you - the 2 fuses etc.
I also show the alternator and its chargeLamp L or D+ circuit equivalence.


The other complication is the parallel cranking which is merely an extra input to the above if the isolator & fuses handle the cranking. (Which they probably won't, but it's easy to get a relay that does!)

If parallel-cranking, it makes sense to improve and use the existing inter-battery cabling (ie starter motor cabling despite having smaller fuses at each battery end).

The parallel cranking is otherwise "simply" a relay that bypasses the fuses at each end of the battery isolator and the isolator itself. That's basically all. Those relays are triggered by the starter circuit (with an optional off switch if desired).


Adding extra inputs like manual activation or cranking to parallel the batteries requires diodes so that the inputs can be joined together. [Try doing that with other isolators! ]
But those diodes could be omitted using other relays instead....


The parallel cranking was added on request.
For isolation only, omit the cranking relays, starter key and diodes - but I think I supplied or linked the "basic" version earlier...(?)

For compatibility with most isolator advertisments - an SPST relay looks like this (but without the 87a part):

or

The problem is time. Time is something I don't have much of what with school ending and my summer college classes coming up...

When I pulled the Lilliput out of the Tercel, I scratched the screen. Luckily, touch and display functionality aren't affected. I'm not sure if you can see the scratch here, but it there.


I hooked it up to my Mac Mini (PPC, not Intel ) and it works fine. There's a bit of a curve in the calibration graph, but overall functionality isn't affected.


Edit: Yes, I know my OSX Dock is cluttered. I haven't cleaned out the previous owner's apps yet. Although she cleaned out all of her files...

Originally Posted by OldSpark

It looks complicated because it shows the complete wiring system.

The only difference between the other isolator(s) and the relay is ONE wire that attaches to the alternator - and if that alternator has only one wire, it should not be difficult to locate.

If it's a 2 or 3 wire alternator, you need to figure out which goes to the charge lamp (which I though you had done).

It is usually far simpler than using a relay from the ignition or accessories.
That has the same "one extra wire" to, but you have to fine an accessories point (usually inside the cabin) or ignition (cabin or engine bay - eg IgCoil).

And as I said, you chose the size of "isolation switch" - 15A, 30A, 60A, 140A, 250A, 400A etc etc.
(Yes - you can add those relays to any isolation switch, but then why bother with the original expensive isolation switch in the first place? )


The complication you refer to is probably the detail others do not show you - the 2 fuses etc.
I also show the alternator and its chargeLamp L or D+ circuit equivalence.


The other complication is the parallel cranking which is merely an extra input to the above if the isolator & fuses handle the cranking. (Which they probably won't, but it's easy to get a relay that does!)

If parallel-cranking, it makes sense to improve and use the existing inter-battery cabling (ie starter motor cabling despite having smaller fuses at each battery end).

The parallel cranking is otherwise "simply" a relay that bypasses the fuses at each end of the battery isolator and the isolator itself. That's basically all. Those relays are triggered by the starter circuit (with an optional off switch if desired).


Adding extra inputs like manual activation or cranking to parallel the batteries requires diodes so that the inputs can be joined together. [Try doing that with other isolators! ]
But those diodes could be omitted using other relays instead....


The parallel cranking was added on request.
For isolation only, omit the cranking relays, starter key and diodes - but I think I supplied or linked the "basic" version earlier...(?)

For compatibility with most isolator advertisments - an SPST relay looks like this (but without the 87a part):

or

So, what size diodes would I need? I see about $40 in 80A relays/thermal circuit breakers (rather than fuses). I'm attempting to see if this way is ultimately cheaper, or if it would just be easier to grab an off-the-shelf (err... Web) isolator.