Possible bad amp, need suggestions

aggybong · Post by **aggybong** » Fri Dec 24, 2004 10:21 pm

I had professionals do the install, and if it was an ohm thing, it wouldn't have started working (briefly) after the new sub was installed, since nothing else was changed.

aggybong · Post by **aggybong** » Sat Dec 25, 2004 4:25 pm

I saw this in the DVC sub faq:

It is not recommended that you run separate channels of an amplifier, or separate amplifiers to each coil of a DVC subwoofer. This requires VERY fine tuning to balance the channels, through the use of an RTA (real-time analyzer) and an oscilloscope. If this calibrating is bypassed, the coils will not receive precisely identical signals, and that desynchronization will cause the coils to fight each other, and what you'll end up with is a very nice, very large paper weight instead of a subwoofer. The resulting damage will consist of a fried voice coil(s).
NEVER wire a DVC subwoofer with just one of the coils, and leave the other disconnected!
This will result in instant damage to the driver, and once again, you'll be looking at buying a new speaker.

How would you run two seperate channels to an sub? The sub channel on the amp has left\right channel RCA jacks, would I need to do something special besides hooking up the RCAs in there? Or would I have to run two seperate speaker wires to the different coils of the sub?

Other ideas: Is it possible to tell if the amp channel is mono or not? After reading this, near the middle of the page where it talks about DVC speakers, I saw this:

This image shows the DVC driver with both voice coils wired in parallel. This presents a 2 ohm mono load to the amplifier which may damage most amplifiers.

Could that be possibly it? I thought wiring a 4+4ohm DVC sub parallel would equal a 2ohm load, which most amps could easily handle. My old Alpine amp didn't have any problems at 2ohms\wired parallel, but I don't know if the installers changed anything or not.

After doing a little more searching, I found this, which contradicts what the above link said. I am confused about this part

I also saw an Input switch on the 5th channel of the amp that listed 1\2 - 5 - 3\4 as the options. Would having that set wrong damage anything?

I honestly don't know what the hell I'm talking about, but I'm trying to learn, so I'm attempting to do research on a few different things.

Ryan from Ohio · Post by **Ryan from Ohio** » Sat Dec 25, 2004 6:46 pm

Lets not concern oursleves with stuff that does not directly apply to your problem.

The specs I find show the output are as follows:

OUTPUT (watts):RMS @ 4 Ohms-50 x 4, 200 x 1 (sub)
RMS @ 2 Ohms-100 x 4, 400 x 1 (sub)
RMS Bridged @ 4 Ohms-200 x 2, 400 x 1 (sub)

This is taken from Soundstreams site and does not make much sense... Pay attention to the Ohms/sub RMS values...The 1/3 are the same, but I believe the 3rd should be 200 also :)

BTW with dual 4 Ohm VC's your amp is seeing that sub as a 2 Ohm sub, so it should be getting 400 WRMS :) So its not an impedance problem...

aggybong · Post by **aggybong** » Sat Dec 25, 2004 7:39 pm

Alright, just checking.

A friend suggested I do some tests on the 5th channel with regular speakers to pinpoint the problem.

Results:

Retested sub alone again, amp still went into protection mode
Put 1 speaker on the 5th channel, result: everything was fine
Put 2 speakers on the 5th channel (2 sets of speaker wire, positives together, negatives togther), result: everything was fine (mimicing 2ohm load, correct?)

Adding the fronts to both setup on channel 1\2 did not affect the system. After it was all tested, I once again put the sub back on the 5th channel, and it once again went into protect mode.

Any ideas on what this new information tells us? Maybe the sub is wired wrong inside?

Ryan from Ohio · Post by **Ryan from Ohio** » Sat Dec 25, 2004 7:46 pm

Sounds like the 5th channel is not working.

It really sounds like the amp now

aggybong · Post by **aggybong** » Sat Dec 25, 2004 7:59 pm

Huh?

I dunno if you misread, but if I hook up regular speakers to the 5th channel, it doesn't turn off. Only when the sub is connected does it start going into protect mode. Doesn't that mean the 5th channel works fine at both 2ohm and 4ohm, and the only thing that is messed up is the sub?

In related news, I opened up the sub. I smell something burnt. It's faint, but there. The sub sounds a little scratchy when I push on it.

I'd call it a blown sub, but don't they usually still work after being blown, they just sound like crap?

Ryan from Ohio · Post by **Ryan from Ohio** » Sat Dec 25, 2004 8:23 pm

Yike, yeah I didnt read that well... Tired...

Thats very odd!

Try rewiring the sub and using all new speaker wire for it. Maybe sumhow it is shorting out?

Short of that who knows...

aggybong · Post by **aggybong** » Sat Dec 25, 2004 8:37 pm

The sub is wired as follows:

Theres a small wire that connects the positive and negative sides to each other, then another set of wire on one side which connects to the amp.

http://www.eatel.net/~amptech/elecdisc/spkrmlti.htm

According to that (middle of the page where it talks about DVC), it says thats a 2ohm mono load, and most amps cannot handle it. Is that true? Is the wiring messed up? That website has a slightly different wiring though, so it's possibly not the same...

I am going to put it back together, and test it on the 1\2 channel, to see if its the 5th channel, or the sub.

aggybong · Post by **aggybong** » Sat Dec 25, 2004 9:42 pm

Alright, the sub makes the amp reset on the other channels as well. Looks like I've been blowing the sub somehow?

Ryan from Ohio · Post by **Ryan from Ohio** » Sun Dec 26, 2004 5:36 am

Take a picture of the wiring on the back of the sub.

Now that I am awake and reading that post it almost sounds like someone wired it up to short out?

In any even just rip ALL WIRING OFF THE SUB! and start over. FOllow the pictures exactly!!!

Also the sub is 300 WRMS and your tossing 400 WRMS at it, not a good idea.

So there are two possiblities:

1) Sub is wired wrong- shorting

2) Sub is blown closed and puts the amp into protect mode