fleabag Posted April 19, 2020 Author Share Posted April 19, 2020 Aha Found internal recording thingy, and its recording the bass, but bizarrely, there is no SAVE button. I dont get it. Such a palava. Back in the cupboard Quote Link to comment Share on other sites More sharing options...
fleabag Posted April 19, 2020 Author Share Posted April 19, 2020 Here's a screen grab. I've tried a couple of times, but since there is no SAVE button, i'm stumped as to why this recording prog even exists Quote Link to comment Share on other sites More sharing options...
fleabag Posted April 19, 2020 Author Share Posted April 19, 2020 Ok, last try - did a phone recording, since at least i can save those to Laptop. Open E plucked at mid point , 12th fret. Then open file in Audacity, and screen shot it, but how this might help, i dont know bass recording.mp3 Quote Link to comment Share on other sites More sharing options...
Mottlefeeder Posted April 19, 2020 Share Posted April 19, 2020 In Audacity, towards the right of the tool bar, there are tools to stretch out the recording in time. Using those, you can expand the view until you can see individual cycles. I can see no sign of crossover distortion. You do have some warbling harmonics - the lighter coloured parts of the trace - but I have no idea if that is normal for a plucked string. David Quote Link to comment Share on other sites More sharing options...
fleabag Posted April 19, 2020 Author Share Posted April 19, 2020 Had a look but couldnt find any " stretch " button. There is something called Analyze , which i tried, and this is what the result was. As above , dont know how useful this is Quote Link to comment Share on other sites More sharing options...
Stub Mandrel Posted April 19, 2020 Share Posted April 19, 2020 Strange! I could swear I posted this earlier... https://academo.org/demos/virtual-oscilloscope/ Quote Link to comment Share on other sites More sharing options...
Stub Mandrel Posted April 19, 2020 Share Posted April 19, 2020 You're looking to get something like this, you may need to experiment with which note you use and thw volts/ division setting. Note the use of 'freeze display' to stop it dancing about: 1 Quote Link to comment Share on other sites More sharing options...
fleabag Posted April 19, 2020 Author Share Posted April 19, 2020 Cheers Stub - though i may feck it up by pressing the wrong buttons. I dont know what i'm doing with something like that Quote Link to comment Share on other sites More sharing options...
Chienmortbb Posted April 20, 2020 Share Posted April 20, 2020 On 17/04/2020 at 18:12, fleabag said: Recording - just using open E. Bass EQ rolled off completely. Sounds like i;m really attacking the string but it was just a normal bedroom level pluck Voice 001.mp3 179.04 kB · 12 downloads check that there are no air leaks in the cab. I had a cab that made a similar noise and it was air leaking out through the jack socket. 2 Quote Link to comment Share on other sites More sharing options...
Mottlefeeder Posted April 20, 2020 Share Posted April 20, 2020 In Audacity, the stretch facility is on the toolbar above 10-11 seconds of the recording. The magnifier with the '+' sign will stretch the whole recording, and the buttons to its right will expand a defined section of the recording. David 1 Quote Link to comment Share on other sites More sharing options...
Mottlefeeder Posted April 20, 2020 Share Posted April 20, 2020 26 minutes ago, Chienmortbb said: check that there are no air leaks in the cab. I had a cab that made a similar noise and it was air leaking out through the jack socket. It's doing it with two cabs... Quote Link to comment Share on other sites More sharing options...
fleabag Posted April 20, 2020 Author Share Posted April 20, 2020 3 hours ago, Mottlefeeder said: In Audacity, the stretch facility is on the toolbar above 10-11 seconds of the recording. The magnifier with the '+' sign will stretch the whole recording, and the buttons to its right will expand a defined section of the recording. David I'll check that - thanks Quote Link to comment Share on other sites More sharing options...
fleabag Posted April 20, 2020 Author Share Posted April 20, 2020 This is zoomed in quite a few clicks, but is it any help or does it need more zoom? Quote Link to comment Share on other sites More sharing options...
Mottlefeeder Posted April 20, 2020 Share Posted April 20, 2020 Keep zooming until you have only 2-3 cycles in view. Then increase the gain if you need to. I cannot see any crossover distortion on this trace. You've tried this amp with two cabs, and got the same result - just to rule out other possibilities, have you tried it with another bass, just in case it is a faulty string, or a string rattling in the nut or a fading battery or something similar? David Quote Link to comment Share on other sites More sharing options...
fleabag Posted April 20, 2020 Author Share Posted April 20, 2020 I'll do bigger zoom , and at the mo, i have only swapped cables, but i have 2nd bass and will try that too Quote Link to comment Share on other sites More sharing options...
fleabag Posted April 20, 2020 Author Share Posted April 20, 2020 Different bass produced same noise. Again, its not so much a fart as a buzzing, both speakers. Hows the graph - any good ? Quote Link to comment Share on other sites More sharing options...
Mottlefeeder Posted April 20, 2020 Share Posted April 20, 2020 On 17/04/2020 at 20:51, Stub Mandrel said: Crossover distortion is if the amplifier isn't set for enough bias current, so when the signal 'crosses over' from negative to positive there's a brief moment where the signal is cut off. It tends to be more noticeable with softer signals as it doesn't increase with volume. Basically the half of the amp that does the top of the signal is switching off before the half that does the bottom switches on. If yours in is a linear class B amplifier (rather than a class D) there's a biasing arrangement in there to prevent it happening. This can go wrong. Sometimes its as simple as adjusting a preset to get the right 'quiescent current' or it could be a diode or transistor needs replacing. The most common cause is when a transistor is used to set the bias current and kept at the same temperature as the power transistors by being held against the same heatsink. If it comes lose you get crossover distortion that gets worse as the amp warms up. Easy to spot if you have a scope (see picture above) but needs a bit of amp repair experience to fix. Looking at your stretched waveform, and comparing it with Stub Mandrel's, I'm not seeing any cross-over distortion, so I'm starting to think about other things it might be. Since the amp has FX out and in jack sockets, have you got anything that will allow you to listen to the preamp output (FX send) or play into the Amp input (FX return)? If you turn down the volume of an active bass, switch off the amp power, connect the bass to the FX return socket, power up and then slowly raise the volume on the bass you should get enough signal to tell whether you still have a problem. If so, then you know it is not the preamp. If you have a mixer or another amp of any description, you can plug your FX send into it and check whether the distortion is being produced in the preamp. Totally off the wall, you could send Ashdown a PM, point them at this thread, and ask them what might be causing the problem, and whether it is DIY fixable. When I had a problem, they satisfied themselves that I was competent, and then sent me a replacement PCB "If it fixes the problem, send the faulty one back, and pay us: or if it doesn't, send the whole amp and new PCB back and pay us to fix it for you." David 1 Quote Link to comment Share on other sites More sharing options...
fleabag Posted April 20, 2020 Author Share Posted April 20, 2020 (edited) I dont own an active bass David, so all tests are done with my passive bass. Edited June 1, 2020 by fleabag Quote Link to comment Share on other sites More sharing options...
Stub Mandrel Posted April 21, 2020 Share Posted April 21, 2020 10 hours ago, fleabag said: now i have an amp head winging its way to me from Thomann, So it was all a ploy... Just for comparison: My A string, neck pickup, tone rolled back: D string, bridge pickup, tone on: Both of my signals look 'smoother'; than yours: 1 Quote Link to comment Share on other sites More sharing options...
fleabag Posted April 21, 2020 Author Share Posted April 21, 2020 They do indeed look smoother . On mine, that scope made my peaks look square on open E and they looked identical with other strings Quote Link to comment Share on other sites More sharing options...
fleabag Posted April 21, 2020 Author Share Posted April 21, 2020 (edited) Just tried again, and now the graph will not work. I know the mic is working because i shouted some obscenities into it and the meter is working fine, jumping up and down to some choice words, but the graph on the scope is not even registering. Screen shot of me swearing into the mic, which has peaked And screenshot of whats happening on the scope... Edited April 21, 2020 by fleabag Quote Link to comment Share on other sites More sharing options...
Stub Mandrel Posted April 21, 2020 Share Posted April 21, 2020 1 hour ago, fleabag said: On mine, that scope made my peaks look square on open E Probably getting clipped, mine does that I had to move the mic back. 42 minutes ago, fleabag said: And screenshot of whats happening on the scope... When you go to the page a popup should appear asking for permission to access the mic, if you miss it and don't click yess it won't work. 1 Quote Link to comment Share on other sites More sharing options...
fleabag Posted April 21, 2020 Author Share Posted April 21, 2020 Dammit - i'll try again and look for that permission Quote Link to comment Share on other sites More sharing options...
fleabag Posted April 21, 2020 Author Share Posted April 21, 2020 Ok - fired up the scope again, though i couldnt get the combo and mic seperated enough to stop that funny squaring off on the peaks, even with the mic level on about number 2 or 3 and the combo 2 metres from the mic Took 4 screenshots at various points - just looks like gobbledygook to me Quote Link to comment Share on other sites More sharing options...
Stub Mandrel Posted April 21, 2020 Share Posted April 21, 2020 Well compared to my traces it does like like you have a lot of high frequency noise but I think that could be the mic/computer. On the other hand the middle traces look a bit 'flat topped' on the higher peaks which would sound like the mild distortion/odd harmonics effect you are getting. So this could be the issue. As only on half a cycle, this could be an offset bias, a failing power supply capacitor or another component on the way out. Next step get someone to take a proper look. Ah well at least we've had some fun.... 1 Quote Link to comment Share on other sites More sharing options...
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