Ampeg V4B reissue Volume Drop with 2 Cabinets

[MYager]

Hey just played last nite and noticed that my volume was significantly lower than normal.
The only thing I did that was a little different from my usual practice set up was add a cab.

I usually use my V4B with one Ampeg SVT 210 HE and its fairly loud with great clean volume.
But last nite I added an extra 210 HE. I plugged both cabs in to the 4ohm jacks, both hooked up directly to the amp, it was QUIET and broke up fairly quick.

During a break in the set I unplugged one cab and ran just one cab through the 8 ohm output and this brought up the volume significantly with a great increase in clean volume.

Any idea why this is happening?? Could it be that the 100 watts isn't enough to drive both cabs??
Or could it be an issue with the head??

 

[High Camp]

Could something be wrong with one cab (or a speakercable?)
Maybe if you daisy chain it, that might work better?
Normally it would go louder.
If the head is working fine with one cab, I would doubt something is wrong with the head.
>> but I'm no technical wonder so my knowledge ends here...

 

[BassmanPaul]

What are the impedances of the two cabinets? Couple the cabinets together and do the battery test to ensure that both cabinets drivers move the same way.

 

[Tbone76]

I think you're only supposed to use one of the 4ohm outputs, and then daisy-chain the cabs. That's how I understood it in the user manual.

 

[B-string]

If the head is fine with one cab it will be fine with 20 cabs (wired for proper impedance). You most likely have a cable problem or a miss-wired cab.

 

[seamonkey]

Just guessing, after the break you plugged into the top cabinet. Therefore all the power was going to one cabinet that was closer to your ears.
When you have the bottom cab also plugged in you have the same power, but some skirts out from the lower cap. You may in fact have been louder with both, but just from where you were standing it sounded quieter. Get someone with a smartphone soundmeter app and have them stand out where the audience is, and at several points measure the difference.

In FOH systems line arrays work like stacking 2x10 vertically and don't beam and scream out power like a point source cab.

 

[B-string]

I think you're only supposed to use one of the 4ohm outputs, and then daisy-chain the cabs. That's how I understood it in the user manual.

You can go that way or use two cables from the 4 ohm jacks to two 8 ohm cabs (total of 4 ohms load). The jacks are wired direct to the output transformer taps

 

[rodl2005]

Perhaps one can was outta phase with the other? ???? I've had this happen with my old lmii but not with the V4B

 

[BassmanPaul]

Check also the wiring of your Speakon cables. One could be miss wired.

 

[JimmyM]

New V4B doesn't use Speakons.

Anyway, I agree with those who say your cabs are somehow mis-wired and out of phase. 100w of V4B through two 210he's should be ripping pretty loud if you need it.

 

[Downunderwonder]

First check your extra cable. Tip to tip and sleeve to sleeve continuity. You wouldn't be using a guitar cable?

If that passes try 9v battery test with daisy chained cabs. All cones should jump together when 9v is applied to the cable that would be in an amp.

Unlikely the amp output sockets are miswired. If it all psssed so far you could try daisy chaining the cabs from one 4ohm outout. Make sure to use a known good cable out of the amp from the known good output. Reason being if there is a dud out you will still have a load on the amp and won't fry the transformer.

If that passes you have narrowed it to the other amp out being dud. Warranty job, either it's reverse wired or not wired but testing puts the amp at risk.

 

[beans-on-toast]

Test just one cab as you did. Try one jack on the SVt210HE connected to the amp, then the other cab jack to the amp. Then unplug the cab and try the other one as above.

If they sound the same, the cabs are ok. If not, you'll know which one has an issue. There is still the possibility that they are wired out of phase to on another as mentioned above.

With one 8 ohm cab connect to the 8 ohm jack on the amp. When connecting two 8 ohm daisy chained cabs plug into the 4 ohm jack on the amp.

 

[MYager]

A ton of stuff to try here. THanks guys, Ill keep you updated. Gonna give this a shot either tonite or tomorrow nite at practice.
I've got a few speaker cables so maybe one has gone bad

 

[MYager]

Found it!!!! Was checking all my cables with an ohm meter and everything tested ok.
Ran both cabs in to the amp and measured output, then ran one cab at the ohm input and measured output
Both cabs were louder, a bit strange because there was a big drop in volume at my last show.

Was checking the back of the amp to see what I could be doing wrong and bumped my monster cable right at the end.
Immediately one cab cut out, was a little worried the jack had a weak solder point so I switched jacks same thing.

Ran a diff amp and noticed and wiggled the monster cable around and sure enough, break in the cable.
You really have to wiggle it for the sound to actually cut completely, it must've been sitting at just the right angle during our performance.

I'm a bit of a worrier so immediately consulted TB.
Sorry for wasting a whole thread, I'm sooooooo relieved
Off to guitar center to have them swap it out!

 

[B-string]

No trouble really. Get them to replace the "Monster waste of cash" cable.

 

[beans-on-toast]

Pat yourself on the back for figuring it out.

 

[MYager]

I got it when I first started out (5or6 years ago) and let some salesmen talk me in to it.
I know better now then to spend $30 on a 6ft speaker cable
Oh well at least it's a $30 cable getting replaced and not a $1200 head hahahaha

 

[beans-on-toast]

If you like it, you might be able to fix the cable if you inspect the connector and find an issue. Maybe a bit of solder or a new plug.

 

[B-string]

Monster has a limited lifetime warranty, might as well get a new replacement (you already paid for 3 to 4)

 

[MYager]

Yeah headed there after work to swap cables out
The nice thing about monster cables is you know youre safe to abuse em a little!