Troubleshooting something totally bizarre

JimmyM · #1 03-09-2011, 11:40 PM

ampeg's cs dept was very helpful about this problem and is supposed to call me tomorrow to discuss this further, so i certainly don't mean this as a slight in case they see this, but in all my years of playing, i have never seen something this odd and i'm dying to find out what it is and it'll probably have me up all night until i find out what it is. it was late in the day and the guy i talked to was stumped as well, so he wanted to discuss it with the head guy and call me tomorrow. in the meantime, it's such a bizarre thing that i thought i'd discuss it with you guys and see if anyone else ever had it happen with their stuff.

micro vr head and two svt 210av's. i take each separate piece and run it into everything else i own and it all works perfectly. the cabs work great in every other amp i have. the amp works great in every other cab(s) i have. the micro vr works perfectly with each 210av separately. but for some reason, when i plug both 210av's in the micro vr, i couldn't turn it up very loudly before i heard a sound coming from the cabs that sounded like when i had a voice coil wire come loose in a recone a couple years ago. no matter what settings i tried, when the volume reached this certain level, i got the raspberry. whether daisy chaining or using both speaker outs, it happened.

yet i slammed those cabs pretty hard with my b-15n, my svt, and my crate power block, and it was all good. i also tried the micro vr into two b-15 cabs and my svt 810, and it was all good even when cranked hard. even tried running the micro vr as a pre into the power block and a vt deluxe into the power amp of the micro vr, and everything was all good. it would only happen when the micro vr and both 210av's were hooked up. and yes, i swapped around all manner of cables and tried it in different circuits in my house, too. cleaned the effects loop jacks, too.

so if anyone has any ideas, i'd appreciate it.

knappymer · #2 03-09-2011, 11:48 PM

And this just happened out of nowhere? Before I read it, I was going to say a phasing issue between the cabs or yea the split voice coil wire. But this is certainly a pickle.

JimmyM · #3 03-09-2011, 11:52 PM

Quote:

Originally Posted by knappymer

And this just happened out of nowhere? Before I read it, I was going to say a phasing issue between the cabs or yea the split voice coil wire. But this is certainly a pickle.

well i just got the second cab today so i never got to try it this way before. i thought of it maybe being a phasing issue, but the cabs work fine in every other head so i didn't think that could be it. you never know, though.

thx!

Selta · #4 03-09-2011, 11:56 PM

So, when you tried the VR with the other cabs, did the impedance match that of the 2x2x10s?

JimmyM · #5 03-10-2011, 12:08 AM

Quote:

Originally Posted by Ray Salamon

So, when you tried the VR with the other cabs, did the impedance match that of the 2x2x10s?

i guess so. the 210av's are 8 oihms each and so are the b-15 cabs. didn't have a meter, but i believe them

dscott11 · #6 03-10-2011, 12:27 AM

I've had a bad speaker cable do weird stuff before...

dscott11 · #7 03-10-2011, 12:28 AM

Sorry, you already tried the cables...

GrowlerBox · #8 03-10-2011, 12:44 AM

You've tried each cab through each of its inputs? If it only happens when you're daisy-chaining, it sounds like something awry between the two outs on one of the cabinets (the one you're chaining out of, presumably). When you plugged each cabinet into a separate speaker out on the amp, did you try it into each input on each cabinet?

JimmyM · #9 03-10-2011, 12:53 AM

Quote:

Originally Posted by GrowlerBox

You've tried each cab through each of its inputs? If it only happens when you're daisy-chaining, it sounds like something awry between the two outs on one of the cabinets (the one you're chaining out of, presumably). When you plugged each cabinet into a separate speaker out on the amp, did you try it into each input on each cabinet?

i did both daisy chaining and using the speaker outs on the head.

Downunderwonder · #10 03-10-2011, 01:01 AM

Like you say, it's a mystery that defies logic so I'd start digging a bit further with the new cab. Loose connection maybe.

GrowlerBox · #11 03-10-2011, 01:02 AM

Quote:

Originally Posted by JimmyM

i did both daisy chaining and using the speaker outs on the head.

Yep, I read that, and I think my question was confusing even to me. I was wondering whether you had connected up the cabinets using all the permutations of the 2 connectors on the back of each cab. Looking at the manual for the cab, it seems that the inputs are labelled "in" and "out", but have you tried plugging into the "out"? On any cab I've had, it makes no difference which "input" you use as "in" and which as "out", and I don't imagine Ampeg parallel wiring is different from anyone else's. Don't mean to teach you to suck eggs, bro, just trying to help narrow down the problem from my own idiotic perspective.

JimmyM · #12 03-10-2011, 01:23 AM

lol...that's cool...that's probably the only thing that i didn't do. dang, i so don't want to set it up again but i have a feeling i will

Arjank · #13 03-10-2011, 01:27 AM

So you run both the 210's via the two output jacks on the rear of the micro vr, right?
When the 210's are 8ohms it should be fine, because it would make for 4ohms. The Micro vr can output 200watts at 4ohms.
But I guess you know this allready

But, in case one of the cabs would be 4ohms due to a manufacturing fault or something else it would make the total impedance pretty low, 2.6ohms. If that would be the case your amp might distort.

But a crackling noise may also be a loose connection or a bad soldering joint in one of the output connectors of the amp (or inside the connector). Did you try both outputs on your amp seperately? So, daisy chain the speakers and use either of the amps outputs.

I think I know what noise you mean. Sometimes when I test loudspeakers I just use some ol' piece of wire and connect it to the loudspeaker(without soldering) and the amp. When the ol' wire is oxidated it will transfer the signal badly and the speaker will give a crackling and raspberry sound when you turn up the amp (sparks will fly, literally)

JimmyM · #14 03-10-2011, 02:34 AM

growler, just tried the outs as ins...same thing.

arjank, i've done all that you suggested already. and while i can't rule it out, both speakers in both cabs work, so i imagine they're running at 8 ohms each.

thanks though!

wave rider · #15 03-10-2011, 02:40 AM

Were the cabs daisy-chained/run together with the other amps?

Did you happen to do the 9V battery test to check the phasing just in case?

Just some troubleshooting thoughts...

=wr=

Arjank · #16 03-10-2011, 02:41 AM

So both amp outs give the same result?
And when using one cab the problem is gone?
Hmmmmm.....
Very strange indeed.
I still think it is a bad soldering joint or some oxidated wiring.

Do you have any other cabs or speakers you can try to hook up to the amp?
I would say, make a short list of all the options you have tried and post it here. Maybe someone can come up with something else to check.

JimmyM · #17 03-10-2011, 02:58 AM

lol! already covered that in the first post, guys!

tried every combination of gear that i own. worked fine except when i used the micro vr and the two 210av's. and though i knew they were in phase, i did the battery test just now and it confirmed it.

Arjank · #18 03-10-2011, 03:11 AM

Ok, summing up the steps you made.

1. the cabs work great in every other amp i have.

2. the amp works great in every other cab(s) i have.

3. the micro vr works perfectly with each 210av separately.

4.for some reason, when i plug both 210av's in the micro vr, whether daisy chaining or using both speaker outs, it happened.

5. slammed those cabs pretty hard with my b-15n, my svt, and my crate power block, and it was all good.

6. micro vr into two b-15 cabs and my svt 810, and it was all good even when cranked hard.

7. running the micro vr as a pre into the power block and a vt deluxe into the power amp of the micro vr, and everything was all good.

Ok, to not forget every step, about point 4. Did you try both amp outs seperately when daisychaining the 210av's?
There must be something we missed....

JimmyM · #19 03-10-2011, 03:17 AM

Quote:

Originally Posted by Arjank

Ok, to not forget every step, about point 4. Did you try both amp outs seperately when daisychaining the 210av's?
There must be something we missed....

didn't miss that one, though

i did try the daisychain in both speaker outs.

definitely something very strange going on. i guess i'll just wait to see what ampeg says at this point since i'm about blown out. this is really one for the ages, huh? thanks for trying to help, guys!

testing1two · #20 03-10-2011, 03:17 AM

For the sake of experimentation have you tried a mismatch combination of cabs? For example using one of your B-15 cabs + one 210AV? This would replicate the 4 ohm impedance but might help you isolate one of the AV cabs as the culprit versus the head. But to be honest that sounds like a lot of cabinet shuffling.

Maybe the rock gods are telling you to get another Micro VR so your rig, like Charlie Sheen, will be bi-winning!