Re: How to Recondition (Reform) Electrolytic Capacitors and Why
Not really related to re-forming, but a good SPICE tip when you're trying to simulate any sort of DC charging phenomenon:
When SPICE analyzes the circuit, it first performs an operating point analysis, essentially what you get by using a .DC analysis command. Then, after that, it runs the selected analysis command around the discovered DC operating point for each node.
The problem in this simulation is that the initial .DC analysis will determine the final, settled DC operating...
montemcguire
Member
Last Activity: 08-28-2022, 07:49 PM
Joined: 03-31-2015
Location: Watertown, MA
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Re: Audio tapes and magnets
I misspoke here - a high static field can alter a magnetic tape's stored signal, as long as the field's magnitude is above the coercivity of the tape's magnetic particles. However, a physically moving or changing magnitude field will be more effective in changing a tape's stored signal. So, a changing magnetic field, due to mechanical motion or a changing field, is able to alter a tape more easily than a static magnetic field. Thanks for your patience!...Leave a comment:
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Re: Audio tapes and magnets
Magnetic tape particles have coercivity, which is the threshold flux required to alter its magnetic polarization. When exposed to a field significantly below the coercivity value, not much will happen to the state of the magnetic particles - there is a field potential that has to be overcome before anything can change.
Print through has to be caused by some sort of a field influencing the magnetic particles that store a tape’s signal. This field could be simply the field from an adjacent tape layer’s particles, but it can also...Leave a comment:
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Re: 6800uf (M) 100v caps trouble
Maybe the problem with the amp is not these caps? The old ones test OK, the new ones test OK, the amp works well with the old caps and the new caps, and then fails with the old caps and then the new caps. Seems that amp failure has little relation to the 6800uF cap. Maybe the power meter itself has a flaky solder joint that causes the needle to peg randomly as the amp is handled during the refitting and testing of this 6800uF cap?
Time to look further at this amp and see what else is going on! For starters, look at the ripple across...Leave a comment:
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Re: Solder Wire v Solder Paste?
Paste can work well, but the one problem I've found is that if it spreads away from the work and doesn't completely flow, you now have oddly conductive solder granules floating around your PCB to clean up.
So, you have to be careful not to be a messy slob like I was, or else you'll have an annoying and potentially dangerous mess to clean up - just a friendly reminder. Aside from this gotcha, paste can be really nice to work with.
Along these lines, how do people who use paste a lot dispense it? I've used it with a squeegee...Leave a comment:
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Re: Carbon film vs metal film resistors
The degree of spiraling depends only upon the resistivity of the deposited film, not whether the film is carbon or NiCr. An untrimmed 'slug' that's closer to its final value requires a shorter spiral, and vice versa.
In general, the spiraling of a through-hole resistor will add a pretty negligible amount of inductance. These days, if that was actually something that affected the circuit, an SMD resistor would be used instead of a through-hole part. An SMD resistor chip has less inductance simply because its terminals are closer...Leave a comment:
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Re: who's up for an experiment?
The typical distortion of a capacitor itself is really low, well below 1 part per million even with a faulty cap. Better caps are on the order of dozens of parts per billion - essentially residual for some of the best distortion measurement setups.
So, an oscilloscope, or even a plain-jane spectrum analyzer is pretty much useless - there is no way at all to resolve distortion on this scale. The best analyzers, e.g. an Audio Precision APx-555, can measure the distortion of faulty caps, but you still have to scrape the...Leave a comment:
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Re: What op amps in side the RME firefaces models?
I disagree. The circuit board itself can have a significant effect on the performance of an analog circuit, as can the power supply and bypassing. Maybe it doesn't matter if you care very little beyond basic function, but the distortion of a circuit and the performance details are not just the result of the parts used....Leave a comment:
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Re: Pioneer SA-510 finicky stereo sound, lots of popping noise and a possible bad cap
Pots and switches often get 'crunchy' when there's DC passing through them, which happens when the electrolytic coupling caps are ancient and leaky, and fail to block DC from the switches and pots. Before you put a huge pile of possibly damaging gunk into the pots and switches, replace all of the electrolytic coupling caps. They're from the Ford administration - they're not expected to work anymore. Modern caps work better anyway.
The good part is that, while the switches and pots...Leave a comment:
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Re: Desoldering station vacuum pump. Looking for recommendations.
That makes sense! I have an FR-300 and the tip clogged, but it wasn't solder that clogged it - must have been cooked flux. Other than clogging, which I guess I could prevent by running the cleaning wire through it regularly, it's a really nice tool! Much nicer than the 808 - better balanced, more suction, easily controllable heat, on-off switch.
Thanks for the hint, and I recommend the FR-300 highly. I do mostly SMD, and it's still very useful - a great tool for cleaning and leveling pads after a part...Leave a comment:
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Re: LM358N or other IC for balanced input?
A 1:1 line input transformer is simple and foolproof. They aren't cheap if you want very high quality, but you can get several hundred volts ground isolation easily, something that an electronically balanced input stage will not do so easily.
The Jensen Isomax series is designed for consumer and pro gear to solve this problem. You don't have to think - just plug it in series with the input. Here's a link to get started: [url]http://www.jensen-transformers.com/home-theater/isolators/[/url]Re: LM358N or other IC for balancedLeave a comment:
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Re: are poly caps really better?
I agree that Tantalum should be avoided. The only situation where it must be used is on the output of certain linear voltage regulators. A solid Ta cap has a specific, and somewhat high output impedance compared to modern caps. This high impedance is needed to assure stability of the regulator's control loop, so modern low impedance caps can't be used.
Fortunately, there are more and more alternatives to these ancient but very popular linear regulators, so hopefully, Tantalum's days are numbered. The regulators that require solid Ta...Leave a comment:
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Re: Need help choosing tone board film caps
From your description, you seem to agree with my perception that polypropylene films sound better than mylar films. In my experience, polypropylene replacements will not lead to harshness, but to a generally more clear and detailed sound - they are much more accurate capacitors, and the only reason that I leave mylars in a circuit is because the 'fog' of a mylar is part of the desired tone of the circuit overall. (Example, I didn't replace the 1uF mylar coupling caps in a client's UREI 1176 that needed to sound 'stock' but restored.)...Leave a comment:
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Re: Replacing polymer cap with standard electrolytic
Are you sure that this cap has broken off? From the photo, it appears that the two pads have never seen solder, and that the color of the pads is similar to the unsoldered portion of some SMD pads at the lower left of the picture.Leave a comment:
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Re: New Members - please post your introductions here
Hello folks! I am both amused and pleased that this forum exists! I'm an electrical engineer and am currently designing high performance pro audio gear. I've had my fun recently with capacitors that misbehave, and look forward to reading about others' experiences and perhaps adding some of my own. Cheers!Leave a comment:
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