SamIAm Posted November 22, 2023 Share Posted November 22, 2023 (edited) Hi BC massive! I've little experience with head/cab setups and need your help/advice regarding a problem I have with such a setup. After attending the SE bass bash I concluded that my small/light combo needed a big brother. I purchased a PJB C4 from here on BC, it arrived yesterday, nicely packed, condition as described (As you'd expect given the glowing feedback for the BCer I bought it from). Set it up as follows: Bass = Ibinex GSRM25, passive pickups. Guitar cable = brand new Fender Deluxe Series Instrument Cable - 5m Amp = TC Electric BH250 (Well, to be accurate it is the amp section of a BG250-208 that had been disconnected from the cab by the very kind person who gifted it to me after my fire. I have vague memories of him mentioning it had been done due to some 'thing' that no longer seemed to be a problem) Amp cable = brand new Stagg 2m S Series Speakon to Speakon Lead Cab = PJB C4 <bass> -> <head> -> <cab> Amp settings: Gain: Passive Pickups. All tone controls set to 12 o'clock (neutral), TonePrint all the way off, master at 12 O'clock. I am finding that when I play the E or B the C4 'rattles' , the sound seems to eminate from the rear of the cab. I have moved it around, away from stuff it might be rattling. I cannot feel any movement of the rear panel. Not a great recording, but with headphones on it does illustrate the rattle I'm talking about ... yech! PJB.wav I would usually go through the process of swapping out all the different bits to try and identify the problem. Different bass, same thing. Different guitar cable, same thing. I've just the one amp, but I moved it back to the TC cab (this also meant a different speakon cable) and .... hmmmm ... not the same, but not good! TC.wav What could it be? The seller said they'd not had this issue and they used a 250W Markbass (So simple old me imagines it is not a power mismatch) Can you share your Advice/Experience/Suggestions please? Could it be the Amp? S'manth x Edited November 22, 2023 by Smanth Quote Link to comment Share on other sites More sharing options...
Lozz196 Posted November 22, 2023 Share Posted November 22, 2023 I had something similar on a cab and it was the tweeter that was causing it, not sure what the exact problem was as got it changed. Might be one of the cones. 1 Quote Link to comment Share on other sites More sharing options...
PaulThePlug Posted November 22, 2023 Share Posted November 22, 2023 (edited) Something simple... wiresor something in side? (Didn't some have a unsecued P clip around a wire that was knocking inside something?..) You tried it on it's side, or upside down? Edited November 22, 2023 by PaulThePlug 1 Quote Link to comment Share on other sites More sharing options...
Downunderwonder Posted November 22, 2023 Share Posted November 22, 2023 I had a rattle like that. I was sure it was the cabinet. It turned out to be the kitchen cabinet instead. The sound you hear first has a tendency to appear to be the only source even when the 2nd sound is louder. If it is indeed the cab a rattle can sometimes be found by sitting on each side in turn to see if it can be killed. 2 Quote Link to comment Share on other sites More sharing options...
SamIAm Posted November 22, 2023 Author Share Posted November 22, 2023 24 minutes ago, Lozz196 said: I had something similar on a cab and it was the tweeter that was causing it, not sure what the exact problem was as got it changed. Might be one of the cones. Thanks @Lozz196 The C4 is a 4x5inch layout, no tweeters. All the cones appear fine (visually) S'manth x Quote Link to comment Share on other sites More sharing options...
SamIAm Posted November 22, 2023 Author Share Posted November 22, 2023 24 minutes ago, PaulThePlug said: Something simple... wiresor something in side? (Didn't some have a unsecued P clip around a wire that was knocking inside something?..) You tried it on it's side, or upside down? Thanks @PaulThePlug, I've tried it tilted and rattle remains., It has feet on one side only ... tho that does not preclude me from trying it in different orientations, I'll give it a go tomorrow at a more 'social' hour for my neighbours S'manth x Quote Link to comment Share on other sites More sharing options...
SamIAm Posted November 22, 2023 Author Share Posted November 22, 2023 10 minutes ago, Downunderwonder said: I had a rattle like that. I was sure it was the cabinet. It turned out to be the kitchen cabinet instead. The sound you hear first has a tendency to appear to be the only source even when the 2nd sound is louder. If it is indeed the cab a rattle can sometimes be found by sitting on each side in turn to see if it can be killed. Thanks @Downunderwonder, there is nothing but unadorned (well, they are painted) walls within 2m and the floor is carpeted ... I'm sure the sound is coming from the cab itself. Like your 'sit' test, I'll give it a go tomorrow. S'manth x Quote Link to comment Share on other sites More sharing options...
sandy_r Posted November 22, 2023 Share Posted November 22, 2023 (edited) hmmm doesn't sound like a rattle to me - more like an intermodulation on certain notes that would suggest earlier in the chain than the cab something like that could just happen in active onboard circuitry, but my guess is its happening in the amp Edited November 22, 2023 by sandy_r 1 Quote Link to comment Share on other sites More sharing options...
SamIAm Posted November 22, 2023 Author Share Posted November 22, 2023 1 minute ago, sandy_r said: hmmm doesn't sound like a rattle to me - more like an intermodulation on certain notes that would suggest earlier in the chain than the cab something like that could just happen in active onboard circuitry, but my guess is its happening in the amp The recording is not great (I'll try to get a better one tomorrow) but even with the TC 208 cab there is some 'rattle' (It's the best word I can find) which does make me question the amp, coupled with the previous owner having mentioned 'something' about it. I don't have a second amp to try, but am trying to figure out how to get hold of an alternative for long enough to give it a go. I could consider lugging the C4 along to my local guitar shop to try an amp or two (Which would be GAK). S'manth x Quote Link to comment Share on other sites More sharing options...
wateroftyne Posted November 22, 2023 Share Posted November 22, 2023 Lie it on it's side / tip it upside-down and see if the same thing happens. If not, it coule be something loose inside rattling. 2 Quote Link to comment Share on other sites More sharing options...
sandy_r Posted November 22, 2023 Share Posted November 22, 2023 (edited) 42 minutes ago, Smanth said: The recording is not great (I'll try to get a better one tomorrow) but even with the TC 208 cab there is some 'rattle' (It's the best word I can find) which does make me question the amp, coupled with the previous owner having mentioned 'something' about it. I don't have a second amp to try, but am trying to figure out how to get hold of an alternative for long enough to give it a go. I could consider lugging the C4 along to my local guitar shop to try an amp or two (Which would be GAK). S'manth x Why not take your bass & amp to GAK first? Ask to try them into a similar PJB cab and a similar cab from a different make. Easier 1st journey, and if all sounds ok then focus on your cab if however you hear a similar sound on your 1st visit you know its down to the amp (and/or the bass?) ...and you've saved a journey lugging the cab across to the North Laines! Edited November 22, 2023 by sandy_r 1 Quote Link to comment Share on other sites More sharing options...
PaulThePlug Posted November 22, 2023 Share Posted November 22, 2023 Check the machine head nuts... and neck screws... 1 Quote Link to comment Share on other sites More sharing options...
sandy_r Posted November 22, 2023 Share Posted November 22, 2023 BTW is the recording direct or mic? If direct, then we're only hearing half the story 1 Quote Link to comment Share on other sites More sharing options...
SamIAm Posted November 23, 2023 Author Share Posted November 23, 2023 (edited) 8 hours ago, PaulThePlug said: Check the machine head nuts... and neck screws... I'm confident it's not the bass (My other bass produces similar sounds and is very different, peizo active pickups; both bases also sound fine thro my combo) 8 hours ago, sandy_r said: Why not take your bass & amp to GAK first? Ask to try them into a similar PJB cab and a similar cab from a different make. Easier 1st journey, and if all sounds ok then focus on your cab if however you hear a similar sound on your 1st visit you know its down to the amp (and/or the bass?) ...and you've saved a journey lugging the cab across to the North Laines! Great idea! S'manth x Edited November 23, 2023 by Smanth Quote Link to comment Share on other sites More sharing options...
SamIAm Posted November 23, 2023 Author Share Posted November 23, 2023 8 hours ago, sandy_r said: BTW is the recording direct or mic? If direct, then we're only hearing half the story It's recorded using a Zoom H1n placed about 2m away on a 15cm tripod on floor; This afternoon I'm going to see if I can find my H2n, use better settings and try another recording. S'manth x Quote Link to comment Share on other sites More sharing options...
sandy_r Posted November 23, 2023 Share Posted November 23, 2023 2 hours ago, Smanth said: It's recorded using a Zoom H1n placed about 2m away on a 15cm tripod on floor; This afternoon I'm going to see if I can find my H2n, use better settings and try another recording. The first recording looks fine - clean signal, good dynamic range If no visible, or other obvious sign of something rattling in the cab, it's still possible that there is intermodulation between the direct sound from the back of the speaker cones and resonating/reflected sound from the back of the cab, for particular frequencies (eg. around the B and E open-strings) Since 2 slightly different frequencies (from source & cab resonances) can cause separate 'beat' frequencies which will include the sum and difference of those 2 frequencies - the sum will sound like a harmonic and the difference will probably be outside the normal hearing bandwidth and just be perceived as vibration TL;DR - the sound could just be caused by cab resonance - but do the easy tests first to eliminate other possible sources (eg amp, bass, etc) good luck! ...if you do visit GAK, give my regards to Gardener St (many fond busking memories) 😉 1 Quote Link to comment Share on other sites More sharing options...
BassAdder60 Posted November 23, 2023 Share Posted November 23, 2023 Are you sure you’re not distorting the input with too much signal gain ? That can sometimes sound like a rattle etc ! ? 2 Quote Link to comment Share on other sites More sharing options...
SamIAm Posted November 23, 2023 Author Share Posted November 23, 2023 40 minutes ago, BassAdder60 said: Are you sure you’re not distorting the input with too much signal gain ? That can sometimes sound like a rattle etc ! ? I’m not sure. Amp is running at 50%. The higher strings sound lovely, perhaps I’m just asking too much low bass. GAK seem to stock the C4 so I can compare an Apple with a newer Apple lol S’manth x 1 Quote Link to comment Share on other sites More sharing options...
sandy_r Posted November 23, 2023 Share Posted November 23, 2023 47 minutes ago, Smanth said: I’m not sure. Amp is running at 50%. The higher strings sound lovely, perhaps I’m just asking too much low bass. GAK seem to stock the C4 so I can compare an Apple with a newer Apple... Here's a comparison of an audio clip from your mic recording, with a clip from a direct recording of my YamahaBBN4 passive - 0.1s of the low E from each. Your recording showing predominantly fundamental with some 2nd harmonic; the Yamaha (no treble cut) showing the same plus some higher harmonics No obvious indication of overdrive (eg signal breakup due to clipping) on the PBJ C4 recording PJB C4, mic recording: Yamaha passive, direct recording: A test of your TC head & bass with a C4 (and also a similar config cab, diff brand?) at GAK looks like the way to go 2 Quote Link to comment Share on other sites More sharing options...
tauzero Posted November 23, 2023 Share Posted November 23, 2023 Have you tried the amp with headphones to eliminate that as a possible cause? 1 Quote Link to comment Share on other sites More sharing options...
SamIAm Posted November 23, 2023 Author Share Posted November 23, 2023 13 minutes ago, tauzero said: Have you tried the amp with headphones to eliminate that as a possible cause? Brilliant! I’d thought about recording the DI output but then realised it would not show any issues with the power amp, but hopefully the headphones will 😊 S’manth x Quote Link to comment Share on other sites More sharing options...
SamIAm Posted November 23, 2023 Author Share Posted November 23, 2023 An update. The previous owner of the TC amp shared that he’d had no such issues, so less of a suspicion of the amp. S’manth x Quote Link to comment Share on other sites More sharing options...
SamIAm Posted November 23, 2023 Author Share Posted November 23, 2023 1 hour ago, sandy_r said: Here's a comparison of an audio clip from your mic recording, with a clip from a direct recording of my YamahaBBN4 passive - 0.1s of the low E from each. Your recording showing predominantly fundamental with some 2nd harmonic; the Yamaha (no treble cut) showing the same plus some higher harmonics No obvious indication of overdrive (eg signal breakup due to clipping) on the PBJ C4 recording PJB C4, mic recording: Yamaha passive, direct recording: A test of your TC head & bass with a C4 (and also a similar config cab, diff brand?) at GAK looks like the way to go Cool! I’d not thought of doing this. I’ve also a scope so could maybe wire up something to directly my monitor/analyse the amp output. S’manth x 1 Quote Link to comment Share on other sites More sharing options...
BigRedX Posted November 23, 2023 Share Posted November 23, 2023 Have you had the cab open yet? I had a weird distortion/rattle sound on my Tokai Talbo Jr guitar which has a built-in amp and speaker. When I took the back off I discovered several ball ends from broken stings attached to the speaker magnet. Removing them also removed the weird sounds. It may be that something has come apart inside the cab and is causing the problem. 2 Quote Link to comment Share on other sites More sharing options...
SamIAm Posted November 23, 2023 Author Share Posted November 23, 2023 (edited) Thanks everyone for your suggestions! So this afternoon was another test to try to find the source of the sound ... all fired up and recording (Tho the wretched SD card won't appear on my laptop!) and try some of the suggestions. Sound still there with the cab on its side or upside down. Face down sound still there, but applying some pressure with my foot to the middle of the back panel and the sound reduced, perhaps even went when I weighed it down ... hmmm, this tends to steer my thinking away from an amp problem. I need to try the amp with headphones but I can't find the jack plug converter thingie, oh the joys of moving! 1 hour ago, BigRedX said: Have you had the cab open yet? OMG ... NO!!! 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'! And when one looks at their construction technique, there is nothing that makes me think removing anything more is even possible, they seem built like the proverbial brick out-house! The RED ARROW is pointing to one of the six holes left by the removal of the two rear skids (As was shown in the BC listing) and I discovered that, with low notes, if I put the back of my hand near any of these holes I can feel air puffing out; Might this be related to the sound. I could try covering them, but don't want to leave any sticky residue from gaffer tape which is the only thing I can think of that might be strong enough. Once I've been able to read the recordings off the SD card, I'm going to send off an email to PJB and seek their insight; also planning to see if GAK have a C4 in the shop I can try (They do sell them) and see how it sounds. I can get low notes without the sound when the amp master is set to 9 O'clock, but at that level the sound output is lower than I achieve comfortably with my Dual Cube Bass LX which is only 10 W (5 W+5 W), which totally defeats the point of having a 125W head driving a 400W C4! Oh mighty BCgods of all things cabs (Such as @stevie, @Phil Starr, @Chienmortbb) have you any ideas/suggestions? It's all taken the shine off what promised to be 'new cab day' S'manth x Edited November 23, 2023 by Smanth Quote Link to comment Share on other sites More sharing options...
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