thanks DJK for the link and your time - - fwiw my Heresy totally stock with KGB 2uF other than something in the upper woofer region, sound more "whole" than a lot of fullrange - they're up kinda high on a wall, turned sideways, no grill - soft and beautiful. Some 6.8uF Obigato motor run in series with battery were ok on an Eminence coax - I might have liked a cheap Russian mylar type better.
old caps for old speakers, makes sense to me. keeping it closer to stock is probably the most wise advice. Not the best for sound , then more mods required.
BTW those Panasonics I linked to will work fine as a full DC block (pulse cap) in a 500W 100KHz SMPS, so I have no doubt they would 'sound' fine in any well designed speaker crossover, modern or old. BTW most big value capacitors were the 'Achilles heel' of the old stuff from the tube days, even over magnetics, where today the opposite is true. eg see choke fed power supplies.
BTW those Panasonics I linked to will work fine as a full DC block (pulse cap) in a 500W 100KHz SMPS, so I have no doubt they would 'sound' fine in any well designed speaker crossover, modern or old. BTW most big value capacitors were the 'Achilles heel' of the old stuff from the tube days, even over magnetics, where today the opposite is true. eg see choke fed power supplies.
Thank you I did!
I see now why the two caps in series was recommended, they are intended to be used with the battery and resistor/resistors. Very interesting about the re-release of the dielectric absorption being strongest at the sinusoidal waveform crossover point (0v). So a 9 volt will work up to an 18v input? Should be plenty for my application.
Great info thanks guys
I have Pioneer speakers in my truck that have Panasonic poly caps (original/stock). They (1" soft domes w/ Panasonic cap) sound great. The Panasonics were designed for Filters as you can see on the data sheet. I plan on buying some for coupling caps as they are radial. I have used Erse PulseX. Like them well enough. PPE series SCR/Solen are nice. I loathe Bennic (aka Dayton) poly caps. Sound quality was that of an Electrolytic. Had a good experience with high voltage polystyrene bypassing Rial Mylar in a B&W.....two weeks ago I replaced the bennic elctro. in my Polk 4x6 plate speakers with Erse PulseX. While it definitely opened up the detail and depth. It seemed to increase the volume also. I drove around with a couple decibels of treble cut for a week or two, when people say the system may be designed for the electro. cap, that seems to be true. I am sure there would have been a larger resistor in my crossover.
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I am working on a design for a passive 1st order Butterworth high pass filter for a XO for a FAST monitor described here http://www.diyaudio.com/forums/full-range/273524-10f-8424-rs225-8-fast-ref-monitor.html and the design calls for a 56uF cap. Typical "audio" caps of this value in poly/metal film, or paper/oil, etc. are egregiously expensive. I could buy a miniDSP for the cost of 2 caps, 2 coils, and 4 resistors. Ugh...
What are people's experience with low cost AC motor caps for a XO? For example, I can get a 50uF 370V cap for $9.30 with free shipping. I can tack on a couple of 3.3uF Panasonic film caps I have lying around and use a LCR meter to dial in the exact value.
Would these sound horrid as the main cap on the main full range driver handling everything above 350Hz?
Here is the $9.30 Temco Industrial Power cap on Amazon:
http://www.amazon.com/Motor-Run-Capacitor-RC0015-Electric/dp/B00FBRWUP0
What are people's experience with low cost AC motor caps for a XO? For example, I can get a 50uF 370V cap for $9.30 with free shipping. I can tack on a couple of 3.3uF Panasonic film caps I have lying around and use a LCR meter to dial in the exact value.
Would these sound horrid as the main cap on the main full range driver handling everything above 350Hz?
Here is the $9.30 Temco Industrial Power cap on Amazon:
http://www.amazon.com/Motor-Run-Capacitor-RC0015-Electric/dp/B00FBRWUP0
It says combustible fluid and terminals are non polarized, sounds like an oil filled dielectric?
These are big motor run caps designed to handle continuous tens of amps current for an AC motor.
On the TEMCo website, it discusses how the internal spiral membrane prevents explosion by causing an open circuit if pressure ever bulges the casing. Sounds like metal foil on paper in oil - good for audio actually. Aren't a lot of boutique mucho expensive caps oil in spiral wound paper?
http://www.temcoindustrialpower.com/product_selection.html?p=run_capacitor_selection_guide
These are big motor run caps designed to handle continuous tens of amps current for an AC motor.
On the TEMCo website, it discusses how the internal spiral membrane prevents explosion by causing an open circuit if pressure ever bulges the casing. Sounds like metal foil on paper in oil - good for audio actually. Aren't a lot of boutique mucho expensive caps oil in spiral wound paper?
http://www.temcoindustrialpower.com/product_selection.html?p=run_capacitor_selection_guide
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https://www.parts-express.com/audyn...lypropylene-foil-crossover-capacitor--027-122
Not so extremely expensive.
Not so extremely expensive.
That is a good price - I was looking at 56uF and they all seemed to be upwards of $27. With 47uF I would need to add 10uF more. I suppose qnty 3 of my 3.3uF Panasonics would finish it off.
I still wonder if this industrial oil filled cannister cap works for audio though.
Motor run capacitors are often of plastic film construction.
Some are polypropylene.
Audio will pass through these plastic film capacitors.
Motor start capacitors are either electrolytic or plastic film. Few if any are polypropylene.
Audio will pass through these.
As filter capacitors, non polypropylene will have higher distortion in some parts of the audio band.
As coupling capacitors, there is virtually no added distortion in the passband. Electrolytic and polypropylene and non polypropylene will all have virtually no audio voltage across them and thus they all behave in the same way and should therefore sound exactly the same, if the parasitics are chosen to not affect the audio band.
But filter capacitors, as mentioned para1 and post28, behave very differently.
Some are polypropylene.
Audio will pass through these plastic film capacitors.
Motor start capacitors are either electrolytic or plastic film. Few if any are polypropylene.
Audio will pass through these.
As filter capacitors, non polypropylene will have higher distortion in some parts of the audio band.
As coupling capacitors, there is virtually no added distortion in the passband. Electrolytic and polypropylene and non polypropylene will all have virtually no audio voltage across them and thus they all behave in the same way and should therefore sound exactly the same, if the parasitics are chosen to not affect the audio band.
But filter capacitors, as mentioned para1 and post28, behave very differently.
I think for $9 I have to buy and listen and measure for myself. Still not sure why a cap acting as an AC coupling vs a filter behave differently. What are the physical parameters of the motor start cap that makes it less suitable for a filter cap in a XO?
We have capacitance value, max voltage, ESR, .... What other measurable parameters are there that are important at audio frequencies? Self inductance would be too large for microwave of course.
We have capacitance value, max voltage, ESR, .... What other measurable parameters are there that are important at audio frequencies? Self inductance would be too large for microwave of course.
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