Calling all SNAXO 2-4 users!

What have I done? I need help please!

I have a SNAXO 2-4 feeding 4x135s. Earlier today it was working fine. I’ve moved 2 of the 135s around to simplify cable-dressing issues. Now I’ve connected it all back up, I have lost the LH channel (Ch1) albeit it is there very faintly.

I’ve gone back to the manual. Both LF outputs are connected by white XLRs to the LH inputs on 2 of the 135s, and both HF outputs are connected to the RH inputs on the other 2 135s, using red XLRs.

When I turn on the LF 135s I can hear the usual ‘crump’ on the respective mid-bass drivers and when I turn on the HF 135s I hear a ‘crack’ on the respective tweeter. These are SBLs.

The channel is missing whether I play CD or stream. I’ve checked that the SNAIC 4 between the SC for the pre and that for the SNAXO is on the right DIN sockets, and with the source collar next to the SC for the pre. I’ve checked all the joints are tight. The XLRs are Morganas so don’t lock at the DIN end.

On the basis that the cracks and crumps suggest I’ve got the speakers connected to the correct amps, and all was working perfectly, I keep coming back to the thought I must have the XLRs the wrong way round but it matches the diagram in the manual.

I also have an intermittent rustling noise on the RH speaker that bears no relation to the volume setting. This may or may not be related to the channel issue - it might be the speaker cables picking something up for example - but as it has also just started since I fiddled around, then I should add it for completeness.

All units recently serviced.

So, the ask, please, is what have I done? What am I missing? At this point it’s not blindingly obvious to me. We’ve had similar threads in the past that I believe related to servicing issues but I don’t believe that is the case here. If I could wind the clock back to 10am, I’d be tempted!

Check your connections, in particular the Inputs on the back of the NAP135s (CH1 or CH2) and the DIN-XLRs you have used. Green banded DIN-XLR = CH1 (LEFT), Red banded DIN-XLR = CH2 (RIGHT).

Richard

Thank you for the rapid response. As I look at the manual, with the 2-4 the HF outputs are the top row and the LF the bottom row, with Ch1 on your left as you look at the back and Ch2 on your right. However the diagram shows the red XLRs connected to the HF and then each of those to Ch2 of the 135 and the green XLRs to the LF and each to the Ch1 of the 135s. This seems counter intuitive but it is in the manual and was working until I fiddled around. I just now swapped sides at the back of the SNAXO as an experiment and so the sound appeared on the LH speakers, not the right. I’m not sure what that tells me, perhaps it just confirms that I’ve lost Ch2.

The reason I’ve not tried all red in Ch2 is that if I do, I’ll send LF to the tweeters, I think.

Unfortunately since the last forum update I can’t post up the relevant picture showing the connections. I’ll have to try talking a photo of my computer son my phone and upload it that way…

Ok. Sorry about the quality but it’s the best I can do until I can find a way to upload again from my MacBook.

Thanks - yes, consistent with what I’m looking at. I’ll look again at the connections but this is what I think I’ve done.

Thanks Adam. Although laid out differently that is consistent with what Richard kindly sent earlier and I confirm, that IS what I’ve done. I’m wondering if I’ve messed up something else but the symptoms are classic mismatch of the XLRs.

Apart from that I’ve only touched the burndies and the SNAIC. Could I have broken something? I’ve moved boxes around of course but they’re pretty robust and I’m very gentle with them.

I’ve been looking through other threads. Apparently muting relays have been an issue. I have wiggled the mute button a few times and voila! volume on the LH channel has shot up, but may not be fully equal to the RHS. I will return to it tomorrow!

What is the pre-amp?

It’s an 82 from the mid-90s Richard. There was some revision to it a few years ago. This morning the balance has been restored as far as I can tell, but the system will take a while to warm up and return to normal service, so I’ll be listening more critically later on. Thanks again for your help and support.

OK thanks Jack. Obviously i can’t really comment on a modified piece of Naim kit (I’ve edited your post to ensure it complies with forum rules), but glad to hear you seem to have resolved the issue.

Thank you for that edit! In addition to my thanks I’d also like to acknowledge what an exceptional body of material and support this community provides. From a technical standpoint, it’s not only the willingness to help but the library of wisdom - being able to search through that led me to the threads that caused me to try the solution I did. Beyond the technical, the musical recommendations and many other shared interests make this one of my top 3 sites.

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