CarvinDCM1000L clipping/protect problem

[chucko58]

There was a thread a while back about Carvin power amps not being happy with Acme 4 ohm cabs. IIRC the issue was the Acme impedance curve dropping below 4 ohms and/or turning reactive at some point, and the Carvin's protection circuit not liking it. Am I the only one who remembers this?

 

[greenboy]

I think Andy used to recommend the pre-DCM Carvin amps. I'm wondering if the DCMs are using the same modules almost everybody else is in micro/min heads. Related to this?

http://www.talkbass.com/forum/f15/acme-low-b-2-f1-problem-educate-me-753546/#post10633617

 

[BassmanPaul]

I've had zero issues running up to four 4Ω B2s on the DCM1000, DCM1500, and DCM1204. No problems either with my pair of Mackie FR1400s. So far my BX1500 is handling a pair also with no issues.

Perhaps Andy was referring to the DCM Light series.

 

[greenboy]

Ooops, indeed that's what I meant, Paul. Chucko, where is this thread? And were correct conclusions drawn?

 

[chucko58]

I didn't find it in a quick search, I may try again later.

Somewhere along the way Andy said "yes, before the drivers are broken in, the impedance can drop below nominal". And bgavin measured and posted the actual impedance magnitude of a Low B-2 at various frequencies... which numbers I copied and squirreled away in my tech stash.

I don't recall which model Carvin - it may have been an R1000 head, which used the same power amp circuit as the contemporary DCM1000.

 

[greenboy]

Yeah, whole different amp. Way different.

 

[AL!EN BA$$]

I got the BBE back and it fixed the slight distortion I was getting but not the clipping problem, It's a shame! I had my drummer bring the amp to Daddy's music to get it looked at and it's having the same problem there. I'm gonna try getting a stronger power amp, a QSC 2,000 watt and try that. It's the 4 Ohm cab, I'm using it bridged, is this incorrect?

 

[BassmanPaul]

Should be fine bridged into 4Ω for 1KW. Running your cab on one channel will only give you 325W.

 

[AL!EN BA$$]

So is that wrong? Cause I'm having to push it pretty hard to get any kind of volume. Should I try hooking It up not bridged?

 

[BassmanPaul]

By all means try the amp with the cabinet on a single channel. If that works well swap the cabling to the other channel. Your amp should have three speakons on the back. One for channel 1, another for channel 2 and third in the middle only used for bridging. No changes need to be made to the speakon cable wiring.

Both level controls should be at full.

 

[BassmanPaul]

As another thought, have you called Carvin about this issue??

 

[AL!EN BA$$]

No I haven't. I should try both channels?

 

[Bass_Pounder]

From the manual:

Use channel 1 INPUT and LEVEL for bridge mode. Channel 2 is not used,


Someone had suggested having BOTH attenuators full open - don't know if it really makes a difference, but I would try it like the manual states.

Use channel 1 input only (make sure the parallel switch is not engaged), and only turn up channel 1 output.

 

[AL!EN BA$$]

So I figured out this setup is only giving me 325 watts, definitely the problem! I'm working on gettin it swapped with an 1,800 watt QSC.

 

[greenboy]

So I figured out this setup is only giving me 325 watts

Why is that?

 

[AL!EN BA$$]

That's what the owner manual says.

 

[Bass_Pounder]

That's what the owner manual says.

*IF* you are running it on only one channel.

*IF* you bridge it properly, it is 1,000 watts.

 

[chunkstyle]

Didn't Andy mention something on the Acme site about power conditioners causing problems?

 

[AL!EN BA$$]

I really need to call him.

 

[BassmanPaul]

So how did the amp perform just using the individual channels???