Jump to content

How much did I screw up?


Recommended Posts

I just realized this a "minute ago"...  I brought my home system out for an event that I  do once a year and in hindsight messed up .  I changed out my normal sub amp setup from 2x ep4000 running bridged at 8 ohm (running 4x 4ohm loads in dual series) yes channel B was always muted/left to do bridged mode.  I changed that to 4x EP4000's running one 4ohm bridged load per amp.  Or so I thought.  

When i disassembled that rack to give an amp to a friend,  I noticed the the dip switches on all 4 were configured to accept and output stereo!  Not parallel inputs so that  I could run one xlr to each A channel of the 4 amps from 4 channels of a dcx2496, Ugh I screwed up and didn't use the dip switches to flip phase on channel B.  I had changed my 2 bridged amps dip switches to the stereo amps settings instead of making all 4 bridged amps, but wired them in proper phase red and red.  :(   I have wired like 3 things out of phase in my life.... mmmm Grrrrrrr.  

So my question is:  What effect does using channel A's positive along with using a maximally attenuated channel B's red/hot side as the negative without sending a signal to "B" have on an amp?  


Link to comment
Share on other sites

I'm surprised they ran like that. It's not making sense to me how they would have a complete circuit using both positive terminals in stereo mode? It's kinda hard to make sense of what you are describing. 

At the end of the day if the amps and speakers both still work afterward then there's nothing to worry about. Just pay more attention next time!

Link to comment
Share on other sites

I have an amp that operates in bridge mode using 1+ and 2- and I have another amp which bridges to 1+ and 2+. The latter does make less sense to me, but it depends on the amps internals I guess. Could probably also run 1- 2- if you wanted. Seems like the dip switch to bridge the amp does less than it seems to. There are also amps which bridge automatically, depending on the wiring iirc.

Link to comment
Share on other sites

I was using 1+ and 2+  on an ep2500, an ep4000, and 2x rmx2450's like they are supposed to be for bridge mode.

The gain was all the way down on ch 2 and I didn't have an xlr plugged into the ch 2 input.  I think having the gain down with no signal may have been important here.

Point taken,  I was exhausted and rushing to get stuff together and loaded in the trailer at 4am so I could get 2 hours sleep before having to drive.  I usually take my time and triple check, but couldn't this time.

Pretty sure I killed a couple of them.

Link to comment
Share on other sites

  • 4 years later...

Randomly came across this old topic and I thought I'd elaborate on what (probably) happened here, in case someone comes across this in the future:

Some amps have their 2nd channel running double reversed. Their input phase is flipped and then the output wiring is also reversed, flipping the phase back. This seems to make it easier on the power supply, since one channel generates a positive voltage swing, while the other goes negative, creating an overall balanced load on the PSU. It's kinda like running bridged.
Since the output wiring is flipped on channel two, 2+ will be neutral. And since both channels are running on the same PSU, ch1 and ch2 have a shared neutral, which means you're running 1+ and neutral, essentially the same as 1+ and 1-. If you hook up 1+ and 2- while feeding both channels the same input, you're running bridged (differential) automatically.

Link to comment
Share on other sites

Join the conversation

You can post now and register later. If you have an account, sign in now to post with your account.

Reply to this topic...

×   Pasted as rich text.   Paste as plain text instead

  Only 75 emoji are allowed.

×   Your link has been automatically embedded.   Display as a link instead

×   Your previous content has been restored.   Clear editor

×   You cannot paste images directly. Upload or insert images from URL.

  • Create New...