|
|
#16
09-17-2014, 04:35 PM
|
|||
|
|||
Aha! Unknown information!
 So, they put a NEW element into the preamp module, and the same UST action occurred? If so, the problem might be in the UST channel of the preamp module. I noticed the preamp apparently uses a charge pump to ramp up the voltage from the AA power supply to 11VDC (if I recall correctly). Perhaps there's a problem with the preamp channel connected to the UST. The sound I was hearing appeared compressed. Perhaps the preamp's internal limiting is damping or clamping the pickup. It wouldn't be unknown for a company to get a bad run of caps or diodes and have them cause erratic performance. Sorry to prattle, just surmising. 
|
|
#17
09-17-2014, 04:46 PM
|
|||
|
|||
|
UST? Sorry, I'm new here, and a google search just revealed 'Unresolved Sexual Tension'...it's a nice guitar but not that nice
 Under Saddle T???? So, yes, they put a NEW element into the OLD preamp, and now I have a new preamp showing the same problem. I'm actually liking your theory about capacitive discharge, because one thing I just noticed is that the problem does not happen for the first few seconds of plugging in the guitar, or so it seemed to me, I need to confirm that. Not sure about the compression, maybe I need to do another recording with the input level down some. I'm recording directly into the front of a Presonus PRO24, so I could turn the level down on that to see if it makes a difference.
|
|
#18
09-17-2014, 04:58 PM
|
|||
|
|||
|
UST- Under Saddle Transducer.
 I like my guitars, but none so much that they could cure Unresolved Sexual Tension... Well, maybe my Strat... The phenomenon of the early working, then later erratic performance could point to the problem I mentioned with the UST preamp channel as well. If, for instance, the charge pump circuit would fail to provide the proper voltage to the UST channel, input from the UST might cause the limiting circuit to clamp the input and diminish or distort the signal. The compression I mentioned was the pinched sound following the initial volume drop when you touch the strings. It was not in the recording. This problem could be endemic to the preamp and due to some failure of a particular component in the preamp. Back in the 90's, a major amplifier maker switched manufacturers in the Orient. The plant they chose to build one model of their beginner amps substituted a larger power transformer for the original, small power trannie. The larger trannie had the same secondary voltage, but supplied considerably more current. The amp worked fine, but the greater inrush current from the larger transformer would blow fuses if you used the amp in areas with slightly higher AC mains voltage. Only a few people in our area- those near the power substations- had trouble. I use this as an example of how a simple component problem can cause irritating symptoms. You could try the saddle. If it doesn't help (which I'm suspecting is likely), then a trip to the service center or dealer is perhaps the best route. Good Luck, Bill. Last edited by BTF; 09-17-2014 at 05:06 PM. Reason: poor typing
|
|
#19
09-17-2014, 05:09 PM
|
|||
|
|||
|
Recorded your Youtube audio to Audacity to see what the waveforms look like. This is a screenshot towards the end where you were tapping the strings and bridge. Almost a slight ringing to the decay of the pulse. It's interesting that the spike amplitude is just about double the average amplitude of when you're strumming. Almost would seem there might be an intermittent connection, but doesn't go with the delay of the onset of the occurance.
|
|
#20
09-17-2014, 06:43 PM
|
|||
|
|||
|
While we're on the subject of piezo pickups and interesting visual phenomena, I'll mention an unusual case I had a while back. I was stringing an older gentleman's Martin equipped with two soundboard sensors.
I have a Presonus Acousti-Q preamp which has a multi-segment LED metering system showing the output of the preamp. Interestingly, while trying the Martin through it, when you pressed on the top of the guitar- not playing, just pressing down on the top- the LEDs would show completely in the red as if there was a large audio signal! It was a very strange occurrence. Pressurizing the guitar soundboard by hand apparently sent some type of inaudible signal through the A-Q!
|
|
#21
09-25-2014, 01:46 PM
|
|||
|
|||
|
Can't imagine how you must feel
I'm picking up an A3M next week which i've already tried but now that I've seen this I'm going to run it through a few more pickup tests. I hope you get your issue resolved soon...good luck
|
|
#22
09-25-2014, 01:50 PM
|
|||
|
|||
|
I contacted Yamaha who told me to take it to one of their service centres, so i am going to do this tomorrow. I'll update the thread when I have any news.
|
|
#24
09-26-2014, 03:44 PM
|
|||
|
|||
|
Hmmm...so after some troubleshooting, it looks like the fault lies with my interface... Focusrite Saffire Pro24.
I can't recreate the problem without the Saffire. I realize that I was asked to take everything out of my signal chain to test, but I wasn't including the **** interface I can get the same noise in the Pro24 with my wife's Ibanez acoustic bass, and my Epi Les Paul. I also have a Focusrite Pro 40, and this does not exhibit the problem. I think there is something in the Pro24 that goes nuts with a pickup for some reason. Time to chase this up with Focusrite, but thankfully my Yammy is fine. Many thanks to everyone on here for all your help with this.
|
|
#25
09-26-2014, 04:00 PM
|
|||
|
|||
|
Are you using the instrument or line inputs when this happens or does it occur with either? I'm assuming the line ins might have enough gain for the guitars output. I presume if you stick a DI box of sorts in between the guitar and the interface the problem doesn't happen(?)
The waveforms I posted seem to exhibit a bit of ringing after the initial pulse, which leads me to think there is something in the circuit that's a slightly inductive. Wonder if something gets kicked into a short self oscillation from the piezo PU?
|
|
#26
09-26-2014, 04:15 PM
|
|||
|
|||
|
I'm using the Instrument input. In fact, it is selectable, the front inputs are combi XLR-Jack. If you plug a jack in, you can choose whether this is at Line or Inst level, and I always chose Inst. I have not tried Line, but I do suspect that won't be high enough.
I don't have a DI box, but I might try going into my mixer and come out of that at Line level, I'm expecting that won't exhibit the problem. I agree that at the heart this is something related to a pickup, but since I can recreate it on an electric guitar, I am really confused. I'm also very confused because I had the same problem with a previous guitar, but that was recreate-able on any amp.
|
|
#27
09-26-2014, 05:55 PM
|
|||
|
|||
|
OK. I'm an idiot. The input signal was clipping. The noise is digital distortion. I set my level according to strumming, not thinking that the muting would be way louder.
My confusion was partly caused by having never heard digital clipping sound like that, but mostly because of the fact that my previous guitar made what sounded like the same noise but purely in the analog domain. All is good now, turned the level down and it sounds sweet! Thanks again folks, esp Bill!
|
|
#28
09-26-2014, 06:09 PM
|
|||
|
|||
|
Quote:
 Good to hear it's sorted out
|
|
#30
09-26-2014, 09:23 PM
|
|||
|
|||
|
Quote:
__________________
Vancebo Husband of One, Father of Two Worship Leader, Music Teacher Oregon Duck Fan Guitars by: Collings, Bourgeois, Taylor Pickups by: Dazzo Preamps by: Sunnaudio Amps by: Bose (S1) Grateful
|
 |
|
| Tags |
| yamaha a3m pop noise |
|
|
