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Really odd fault


ashevans09
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Hello :)

Just wondering if anyone's ever encountered a similar problem to this?

I have an active Sandberg VM5 (haussel PUs, 2 band EQ), and it has this bizarre fault where if I'm playing hard and digging in (particularly on the E and B string) it just completely cuts its output. This doesn't happen all the time, however it happens often enough that I can't trust it for live shows anymore. There doesn't appear to be any pattern to it happening. I've managed to repeat this fault through 3 different set ups and with different cables.

I'm absolutely perplexed. Sandberg want it back at their plant to have a look at it however it's going to cost an absolute load to get it there (there's no way I'm sending it uninsured) however I was wondering if anyone had any similar experiences with this kind of fault and could maybe suggest something? Mansons had a quick (10 minute) shufti at it and couldn't see anything immediately wrong with it. I have a local tech who's pretty decent however it'd probably cost just as much for him to have a look at it as it would to send it to Germany, and there's no guarantee he'd fix the issue.

Any advice would be appreciated, it sounds and plays impeccably however it's just massively disappointing that this is happening, particularly with a bass that cost so much. Also anyone who knows a courier who'll insure it at a reasonable rate would be helpful!

Thanks,

Ash

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[quote name='Machines' timestamp='1376838604' post='2179733']
Changed the battery too ? Does it happen in passive mode ? I also had a similar 'fault' with my G&L which turned out to me the cable not being 100% in the socket.
[/quote]

Heya :)

Thanks for the quick response! I've changed the battery and have never encountered it happening in passive mode. I'll be honest I did wonder if what you described was the issue since it seems to have really not agreed with some cables, but to my eyes it appeared (and felt) completely in the jack when it happened? Worth someone having a look at the jack input maybe?

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[quote name='ashevans09' timestamp='1376838884' post='2179737']
Heya :)

Thanks for the quick response! I've changed the battery and have never encountered it happening in passive mode. I'll be honest I did wonder if what you described was the issue since it seems to have really not agreed with some cables, but to my eyes it appeared (and felt) completely in the jack when it happened? Worth someone having a look at the jack input maybe?
[/quote]

Checking the jack is a good call, most active circuits use a stereo jack that's wired to make the power connection on the active circuit when a mono plug is in. If that part of the jack is faulty it may be cutting the power to the active circuit, but therefore not causing a problem running passive. (They're wired that way so the active circuit doesn't drain the battery when the bass isn't plugged in).

Shouldn't take an experienced solderer too long to replace the jack socket, probably cheaper than sending it back to the factory, but it might invalidate your guarantee.

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[quote name='Fat Rich' timestamp='1376839259' post='2179749']
Checking the jack is a good call, most active circuits use a stereo jack that's wired to make the power connection on the active circuit when a mono plug is in. If that part of the jack is faulty it may be cutting the power to the active circuit, but therefore not causing a problem running passive. (They're wired that way so the active circuit doesn't drain the battery when the bass isn't plugged in).

Shouldn't take an experienced solderer too long to replace the jack socket, probably cheaper than sending it back to the factory, but it might invalidate your guarantee.
[/quote]

I didn't know that! Learn something new every day eh? :) . In all honesty Sandberg have been very quick in responding to emails and very helpful so I can't fault them so far, I'll drop em an email and see if we can both agree this is the best way to go.

Fat Rich and Machines, thanks again for your help :)

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[quote name='stingrayPete1977' timestamp='1376905211' post='2180489']
Could the pickup be to high giving too much signal thus over loading the pre?
[/quote]

Never heard of this before.
Had a ray and a sandberg basic with the pickup set very high and I dig in a lot, never had any cutting out.

Be sure it's the bass and not an amp or pedal or anything else.

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[quote name='geoffbyrne' timestamp='1376865505' post='2180243']
Sounds to me like when you're digging in, the pre is overloading & protecting itself by cutting. As you say you haven't experienced this in passive mode, it points to the pre.

G.
[/quote]
this sounds very likley to me as i have owned two basses that did exacty this.
Two basses with Bartolini pre amps & a Zon Sounus

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[quote name='artisan' timestamp='1376920047' post='2180845']
this sounds very likley to me as i have owned two basses that did exacty this.
Two basses with Bartolini pre amps & a Zon Sounus
[/quote]

Really??? I've never heard of any audio preamp working like this - surely if the pickup overloads the input it just distorts a bit?

This is called "clipping", where the output of the preamp saturates due to reaching the limitations of the power supply rails or other circuit limitations - e.g every mixer I've ever used has an LED "clip" indicator, which tells you to turn down the input gain a bit. Imagine what live shows would sound like if the entire channel cut out every time the sound engineer let a channel clip momentarily?! :lol:

Completely cutting out sounds like a fault or a total preamp design fail IMHO.

I'd try replacing the battery, then wiggling the cable in the jack, and if that doesn't work consider taking the backplate of and gently prodding the wires to provoke the cutting out, it could be an intermittent internal cable, or a dry solder joint on the preamp PCB.

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[quote name='artisan' timestamp='1376928810' post='2181043']
Err yes really.
I think i know the difference between clipping & momentary silence.
On my basses there was no other fault just the pre cutting when i dug in like a maniac.
[/quote]

Weird! T[color=#282828][font=helvetica, arial, sans-serif]otal preamp design fail it is then! ;)[/font][/color]

[color=#282828][font=helvetica, arial, sans-serif]Btw, I wasn't implying that you didn't know the difference between clipping and cutting out, merely that a properly designed, non-faulty preamp should always clip on saturation, not cut out, IME/IMO.[/font][/color]

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no worries :)
both the Bartolini pre's were the MK1 type & both on Cort basses too -- no more Bart' mk1's for me
where as my Zon was the import Sonus 4.
really weird, mid gig i'd get carried away & really dig in (finger stylee) then the buggers just went quiet on me,only for a second but damn annoying.

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[quote name='artisan' timestamp='1376938830' post='2181271'] no worries :) both the Bartolini pre's were the MK1 type & both on Cort basses too -- no more Bart' mk1's for me where as my Zon was the import Sonus 4. really weird, mid gig i'd get carried away & really dig in (finger stylee) then the buggers just went quiet on me,only for a second but damn annoying. [/quote]

This is almost exactly what I experienced. I'd be having a ball onstage and then my entire rig would go silent. It would last more than a few seconds though. By the end of the tour I was so used to it cutting I had my switchover down to the ten second mark! :P Problem was at that point I was still blaming my wireless (which had its own issues) and since the bass was brand spanking new and had arrived from Germany 3 days before heading out I kind of assumed it wasn't the problem.

I love this bass but my Spector was so much more reliable. Kind of wish I hadn't sold it on now :( . The current lowest quote I can get is around the £140 mark to get it to Germany (insurance is what's really driving up the price). I really can't afford that at this point. I've emailed asking whether they'll accept just the body, hopefully that'll do the trick :) .

A quick question then, if this is the preamp is this a faulty one or are they just designed to do that? If that's the case I reckon I'll need to move it on :( . I'm not a light player - particularly when I'm mid set.

Again, thanks guys, you know everything!

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[quote name='Prime_BASS' timestamp='1376906159' post='2180504'] Be sure it's the bass and not an amp or pedal or anything else. [/quote]

Heya :) , yeah I initially thought it was a rig issue too, however I've repeated it on now four different rigs (my mesa/matamp rig, through guitar rig 4 on my mac, directly into a friend's PA with his own cables, and through a hartke head into my matamp) with different (and sometimes new) cables that have worked fine with other guitars. Really quite annoying haha!

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[quote name='ashevans09' timestamp='1376950690' post='2181545']
A quick question then, if this is the preamp is this a faulty one or are they just designed to do that? If that's the case I reckon I'll need to move it on :( . I'm not a light player - particularly when I'm mid set.
[/quote]

As mentioned above IMHO there is a fault, no audio electronics designer would intentionally design a preamp to do this. What they *might* do is use components which shut down below a particular voltage (e.g many op-amps), so definitely make sure your battery is new (and something decent, e.g Duracell or similar), and that there isn't any corrosion on the battery clips, the clips are tight, or other bad connection (kinked/broken wires etc)

Does it do it on both pickups when each is soloed? If so then you've removed bad pickup wiring as the cause.

Can you provoke any crackling or cutting out when turning the volume up and down?

Can you provoke anything by wiggling the lead in the jack?

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