Protect a soundcard from voltage surge from valve pre?
- Thread starter mikka
- Start date
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It's hard to say without having further details.
Would depend on the circuit in question and many other parameters. If you fear this, use two 10V (or 5V) zeners back-to-back shorting the input of your soundcard. That should take care of most power-on transients..
Jakob E.
Would depend on the circuit in question and many other parameters. If you fear this, use two 10V (or 5V) zeners back-to-back shorting the input of your soundcard. That should take care of most power-on transients..
Jakob E.
Thanks Jakob....I'm not smart enough to think of details. Power on pops, accidental overloads, a coupling cap shorting out....I've had Sprague orange drops do some funny things from time to time. That's about the best that comes to mind. It's just that my soundcard costs serious $$ and Im trying to cover all possibilities.
An interfacing transformer would probably be the best insurance for your soundcard.. And very often, it sounds nice too.... :razz:
Thank you. As I stared at the ceiling last night thinking (yes, me too, Flatpicker....Prodigy DIY is addictive) I ended thinking......mmmm...I'd better go transformer out. Cost is relative, but I couldn't afford to replace my soundcard at the mo.
And so, another V-72 project will be underway.... as soon as I can.
Thanks again.
And so, another V-72 project will be underway.... as soon as I can.
Thanks again.
Or permanently protect your soundcard (line) input with some 10K:10K transformers..
bcarso
Well-known member
Jakob: "Or permanently protect your soundcard (line) input with some 10K:10K transformers.."
Are you counting on the winding resistance coupled with the input impedance of the soundcard to limit current?
A sufficiently high input Z soundcard could still be blasted with overvoltage I would think.
OTOH I would imagine most soundcards have some protection intrinsically.
Can't resist some war story blah-blah here (busy browsers forewarned!).
So I get an email saying Micr*soft is up in arms about a powered speaker I designed for H*rm*n. Seems some guy testing it blew up his soundcard because there was some fault condition inside the unit. He's calling for a recall etc. etc., citing safety issues etc.
My boss says oh I'm not concerned. Probably some idiot that took his speaker apart, broke it, and now is making up a story.
I then get copied on the original thread and find out that this putative "idiot" is none other than Keith Johnson (Pacific Microsonics, Reference Recordings, Spectral, etc. etc.---truly brilliant guy).
Fortunately I know Keith so I gave him a call. Seems he concluded based on the failure mode, that the neutral side of the a.c. line was tied to the system input ground!! He was using one of these balanced power setups so had 60VAC either side of his system ground going to the unit under test. It promptly blew out the output stage of his Pacific Microsonics DAC before blowing a breaker.
I assured him that this was an anomaly and that we would never tie neutral a.c. to anything except the transformer primary. Unfortunately he had taken the unit apart and destroyed the evidence, so it was up to us to figure out how in the hell neutral could get tied to system common. It appeared far-fetched but was probably a mis-installed bracket-insert in the plastic housing that got forced down across some traces.
Work instructions were modified to provide for a test for this condition! But that was evidently (the problem would have caused likely horrible hum in a non-balanced a.c. power situation thus triggering a customer complaint) the only unit for which this occurred. And it wound up in Keith's hands!
Truth as usual stranger than fiction.
Brad
Are you counting on the winding resistance coupled with the input impedance of the soundcard to limit current?
A sufficiently high input Z soundcard could still be blasted with overvoltage I would think.
OTOH I would imagine most soundcards have some protection intrinsically.
Can't resist some war story blah-blah here (busy browsers forewarned!).
So I get an email saying Micr*soft is up in arms about a powered speaker I designed for H*rm*n. Seems some guy testing it blew up his soundcard because there was some fault condition inside the unit. He's calling for a recall etc. etc., citing safety issues etc.
My boss says oh I'm not concerned. Probably some idiot that took his speaker apart, broke it, and now is making up a story.
I then get copied on the original thread and find out that this putative "idiot" is none other than Keith Johnson (Pacific Microsonics, Reference Recordings, Spectral, etc. etc.---truly brilliant guy).
Fortunately I know Keith so I gave him a call. Seems he concluded based on the failure mode, that the neutral side of the a.c. line was tied to the system input ground!! He was using one of these balanced power setups so had 60VAC either side of his system ground going to the unit under test. It promptly blew out the output stage of his Pacific Microsonics DAC before blowing a breaker.
I assured him that this was an anomaly and that we would never tie neutral a.c. to anything except the transformer primary. Unfortunately he had taken the unit apart and destroyed the evidence, so it was up to us to figure out how in the hell neutral could get tied to system common. It appeared far-fetched but was probably a mis-installed bracket-insert in the plastic housing that got forced down across some traces.
Work instructions were modified to provide for a test for this condition! But that was evidently (the problem would have caused likely horrible hum in a non-balanced a.c. power situation thus triggering a customer complaint) the only unit for which this occurred. And it wound up in Keith's hands!
Truth as usual stranger than fiction.
Brad
