Bill Fitzmaurice Posted November 23, 2023 Share Posted November 23, 2023 If pressure on the back stops it I suspect the glue joint between the back and the brace has failed. A couple of screws would fix that. 2 Quote Link to comment Share on other sites More sharing options...
sandy_r Posted November 23, 2023 Share Posted November 23, 2023 (edited) 1 hour ago, Smanth said: ...Tho the wretched SD card won't appear on my laptop! ... The only bit on the back that slightly hints at being removable might be the panel with the speakon connectors on it ... Re. the zoom SD card no show - could be the computer OS throwing a hissy fit that the SD filing system is 'not recognised'. I get that with Widnose sometimes, determined to reformat all 'foreign' filing systems. Also watch out for popup windows giving options about how to interface with the card/USB as a new folder Are you able to connect the recorder to the computer via USB cable, rather than load the SD card direct? I use that as my preferred transfer method now, on my Zoom H2 Re. access to back of PJB C4 cab - it could be that all access is expected via the front, after build completion (removing drivers, of course). Fun! Edited November 23, 2023 by sandy_r 1 Quote Link to comment Share on other sites More sharing options...
Bill Fitzmaurice Posted November 23, 2023 Share Posted November 23, 2023 4 minutes ago, sandy_r said: it could be that all access is expected via the front, after build completion (removing drivers, of course). That's SOP with monocoque construction. 1 Quote Link to comment Share on other sites More sharing options...
sandy_r Posted November 23, 2023 Share Posted November 23, 2023 2 minutes ago, Bill Fitzmaurice said: That's SOP with monocoque construction. ...indeed - but not S to the OP, apparently 😉 1 1 Quote Link to comment Share on other sites More sharing options...
stevie Posted November 23, 2023 Share Posted November 23, 2023 I can't hear the sound files on my PC. However, if pressure on the back panel reduces the unwanted noise, it might be worth checking out the input panel. See if pressing on it helps. It might be that the input panel hasn't been tightened up properly or hasn't been sealed with foam strip. As far as I can tell from the photo, the screws are socket screws - so you'll need an allen key that fits. The upholstery job on the back looks like it was done on a Friday. 1 Quote Link to comment Share on other sites More sharing options...
stevie Posted November 23, 2023 Share Posted November 23, 2023 Can you close up the holes on the back panel with matchsticks or similar? Just to eliminate those as a possible cause. 1 Quote Link to comment Share on other sites More sharing options...
Dan Dare Posted November 23, 2023 Share Posted November 23, 2023 2 hours ago, stevie said: Can you close up the holes on the back panel with matchsticks or similar? Just to eliminate those as a possible cause. I'd be more inclined to try screws. Is that the C4 that was for sale on here recently? If so, a couple of us noticed that the plastic "feet" (for want of a better word - they are long pieces of shaped black plastic that run virtually the full height of the cab) were missing from the back of it. The screws to hold them in place use the three screw holes on each side of the back panel that you can see in the photo. I don't know what the purpose of the plastic thingiies is (both my C4s have them, so they are obviously a standard fitment), but I wonder if they and the screws serve some kind of structural function. They can't be feet as they are on the rear of the cabs, not the bases. Quote Link to comment Share on other sites More sharing options...
sandy_r Posted November 23, 2023 Share Posted November 23, 2023 7 minutes ago, Dan Dare said: I don't know what the purpose of the plastic thingiies is (both my C4s have them, so they are obviously a standard fitment), but I wonder if they and the screws serve some kind of structural function. They can't be feet as they are on the rear of the cabs, not the bases. 'anti-crush protection' for cables/connectors in the speakon panel? (so you can't jam the cab back against a wall, etc) 1 Quote Link to comment Share on other sites More sharing options...
Phil Starr Posted November 24, 2023 Share Posted November 24, 2023 Hi Smanth, don't panic, whatever it is can be sorted. You can start by blocking those holes, and maybe sticking down the loose vinyl at the back of the cab. Just find some screws the right size to screw in the holes, you don't want to make them any bigger. You could even cut a couple of strips of wood the size of the old plastic strips and screw them on temporarily. It may not fix the problem but you have eliminated one possible cause. I have a minor problem here so I'll only dip in rarely for the next week or so. 1 Quote Link to comment Share on other sites More sharing options...
BigRedX Posted November 24, 2023 Share Posted November 24, 2023 14 hours ago, Smanth said: The only bit on the back that slightly hints at being removable might be the panel with the speakon connectors on it (YELLOW ARROW) ... but this is 'above my pay grade'! It's just a question of undoing the screws, carefully lifting out the panel and then shinning a torch inside to see if there's anything attached to the back of the magnets and feeling around inside for anything loose rattling about. Looking at the photos of the cab on the PJB website removing the top carry handle should also give access to the insides. However if you really don't want to do this I'd start by blocking off the additional screw holes that are letting air out and see if that makes any difference. 1 Quote Link to comment Share on other sites More sharing options...
Woodinblack Posted November 24, 2023 Share Posted November 24, 2023 14 hours ago, Smanth said: The only bit on the back that slightly hints at being removable might be the panel with the speakon connectors on it (YELLOW ARROW) ... but this is 'above my pay grade'! Why you have no problems taking things apart? Take that panel out and make sure that the sockets aren't loose inside or something, should be easy and will let you see if there is anything else loose in there. 1 Quote Link to comment Share on other sites More sharing options...
Dan Dare Posted November 24, 2023 Share Posted November 24, 2023 The Speakon sockets on the C4 are attached to a small PCB, to which the cables for the drive units are soldered. There is quite tightly packed wadding inside the cab, which should help to prevent mechanical rattling. The rear panel is permanently attached. The C4 is quite a solid thing, with small panels and fairly substantial bracing. Access to the inside is only possible via the front, necessitating removal of the drivers. The noise on the sound clips posted above sounded more like break-up or distortion than a rattle to me. Is the bass active? Does the battery need replacing? One would expect a rattle to happen all the time, rather than on certain notes. The cab looks to me to have been well used. I'd try it with another amp. If the problem persists, I'd ask the seller for a return/refund. If you go poking about inside it, it could be claimed that you've caused (or worsened) the issue yourself. 2 Quote Link to comment Share on other sites More sharing options...
itu Posted November 25, 2023 Share Posted November 25, 2023 I checked the picture of the cab and read Rihanna instead of Piranha. It is time to go to bed. 2 Quote Link to comment Share on other sites More sharing options...
SamIAm Posted November 30, 2023 Author Share Posted November 30, 2023 (edited) So ... The lovely @Chimike welcomed me to his Aladin's cave of most things bass yesterday and kindly shared his skill in trying to resolve the issue. After a listen, he described the sound as 'chuffing' rather than a rattle. Dissapeared into the treasure trove and when he emerged he popped 6 screws into the holes in the C4's back panel (Where the skids had lived). No more chuffing! Playing my bass/head, my bass his head, his bass his head ... all sounded OK, tho there was some power tool noise from adjacent workshops and we were outdoors (To avoid any resonance from all the gear he has ... it seemed to go on for miles, but in reality was probably just kilometers) so hard to guage, but a good sign. I arrived home to late yesterday too try it out, but late afternoon when I got home from work I hastened to get my rig setup ... and it sounds fab! A very happy camper! Thank you all for your suggestions. By the way, the seller (Top man and why BC is THE place to buy) totally lived up to his glowing feedback, despite not having experienced the chuffing himself he had offered to either refund me or cover the cost repair. @Chimike refused to let me pay for the screws (Or his expertise). I'm delighted that neither were required. I've fallen in love with the my dimunitive C4 and, whilst it is heavier than I had aimed for in a cab, a hand cart will easily sort that! S'manth x Edited November 30, 2023 by Smanth 3 2 Quote Link to comment Share on other sites More sharing options...
Woodinblack Posted December 1, 2023 Share Posted December 1, 2023 On 30/11/2023 at 18:05, Smanth said: I've fallen in love with the my dimunitive C4 and, whilst it is heavier than I had aimed for in a cab, a hand cart will easily sort that! Glad it is sorted - obviously something on the back of those screws! How heavy are you talking? I like the look of the C4, but not keen on additional weight Quote Link to comment Share on other sites More sharing options...
SamIAm Posted December 1, 2023 Author Share Posted December 1, 2023 1 hour ago, Woodinblack said: Glad it is sorted - obviously something on the back of those screws! How heavy are you talking? I like the look of the C4, but not keen on additional weight 13Kg S'manth x Quote Link to comment Share on other sites More sharing options...
Downunderwonder Posted December 2, 2023 Share Posted December 2, 2023 2 hours ago, Smanth said: 13Kg S'manth x Ime just heavy enough to be a pain walking longer than a couple of blocks if the handle is less than fully comfortable. Quote Link to comment Share on other sites More sharing options...
SamIAm Posted December 2, 2023 Author Share Posted December 2, 2023 12 hours ago, Downunderwonder said: Ime just heavy enough to be a pain walking longer than a couple of blocks if the handle is less than fully comfortable. I can just about manage a couple of meters! But I've a bad back, which is why I try to get the lightest gear I can. A small hand cart works great for me, but the one I've got currently is at its limit with this cab and it has tiny wheels so stairs are challenging. S'manth x Quote Link to comment Share on other sites More sharing options...
Downunderwonder Posted December 2, 2023 Share Posted December 2, 2023 4 hours ago, Smanth said: stairs are challenging. They make these things called 'young chaps' that deal with that. 1 Quote Link to comment Share on other sites More sharing options...
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