Im wanting to change my old caps out and try the new claritycaps polypro caps
they are rated at 320uf. 600vd
Does anyone see a problem doing so?
they are rated at 320uf. 600vd
Does anyone see a problem doing so?
Other than size there should be no particular issue, where I can fit them I generally use polypro instead of electrolytics.
Provided nothing in the circuit is relying on the electrolytics being slightly lossy at high frequencies (e.g. so-called 'bypass caps') then it should be fine, apart from size and cost. Probably unnecessary, though.
Is this for an HV supply?
if you are planning this mod for a 400Vdc to 550Vdc supply then no problems.
It is often suggested that Motor run capacitors are a good substitute for HV supply capacitors (<400Vdc).
Some motor run capacitors are metalised polypropylene and perform better than voltage equivalent electrolytics in HV supplies.
if you are planning this mod for a 400Vdc to 550Vdc supply then no problems.
It is often suggested that Motor run capacitors are a good substitute for HV supply capacitors (<400Vdc).
Some motor run capacitors are metalised polypropylene and perform better than voltage equivalent electrolytics in HV supplies.
On the contrary, one of the most impressive improvements in our amps, particularily if SE
dave
A whole lot more DDR for one. More clarity for another. In an SE amp thw last cap(s) in the PS are in the signal path.
dave
dave
Double Data Rate.....Oh wrong forum
Downward Dynamic Range.....The loud stuff won't get any louder, but the quiet stuff may get quieter because there is less crud coming out of the power supply.
An electrolytic cap is far from perfect. It has significant Effective Series Resistance and ESL (inductance). This is important at higher frequencies because the inductance reduces the ability to filter out high frequency noise and hiss.
I have recommended the addition of a poly cap across the electrolytic in my amps since day one. The electrolytic provides the bulk energy storage and the poly cap's low ESR provides for a low impedance power supply at the higher frequencies.
My hearing is far from the "golden ears" range, but even I can notice a big improvement in dynamics. The impact of a drum hit is improved.
The people who have added the poly cap to their Tubelab amps have "heard" all sorts of improvements, but the common comments are dynamics, better bass, less hiss and hum, and better imaging. All of these are believable based on sound engineering principles.
All of the reasons cited above, and I use them frequently in my highest voltage designs because they are available with kilovolt ratings whereas electrolytics are not.
Where space and funds are available I greatly prefer them for a rather practical reason. I've lived long enough that in some gear I am now in my third round of electrolytic cap replacements, and generally good quality films will never have to be replaced. I don't know about you, but replacing caps in otherwise reliable tube gear is a big nuisance I can do without. Cheaper in the long run too particularly when you are talking a kV or so of B+.
Where space and funds are available I greatly prefer them for a rather practical reason. I've lived long enough that in some gear I am now in my third round of electrolytic cap replacements, and generally good quality films will never have to be replaced. I don't know about you, but replacing caps in otherwise reliable tube gear is a big nuisance I can do without. Cheaper in the long run too particularly when you are talking a kV or so of B+.
polyprops as small as 17mfd measure very well on my test eq. at 100k for very low esr . so much so the leads become more of an ESR problem than the caps. Bypass need to be close to the load not the power supply well at least that's my experience. Andrew T is very correct Psud2 is very instructive .
I have recommended the addition of a poly cap across the electrolytic in my amps since day one. The electrolytic provides the bulk energy storage and the poly cap's low ESR provides for a low impedance power supply at the higher frequencies.
What is a good value cap would you recommend for this? Or would any small value polypro cap work?
What is a good value cap would you recommend for this? Or would any small value polypro cap work?
We use motor RUN (not start) caps from air conditioning units in the Tubelab amps. These caps are designed to create a phase shift at 60 (50) Hz in the stator of a 1/2 horsepower (or so) motor. They connect directly to the AC line and pass several AMPS of AC current for ever. Their electrical performance must be outstanding, otherwise they would simply explode!
You can usually find 50 to 100 uF 370 VAC motor run caps on Ebay for under $25. These are good for about 500 to 550 VDC. Higher voltage units are available, but not common.
Note that a motor START cap is a non polarized electrolytic and useless for this application. Some Chinese vendors are selling start caps as run caps. If it is in a black plastic can, avoid it. The good run caps are in a metal can.
I have found 10 or 20 uF poly caps surplus in a few places. These are nearly as good as a motor run cap if space is an issue. I have one in my small Lexan TSE amp.
Placing a small value poly cap across the electrolytic is usually better than no cap, but it's small size doesn't help with energy storage much.
Boutique poly caps are OK if you want to spend big bucks. They may be the only option in the higher voltage ranges. I did get some surplus "UNLYTIC" poly caps from another forum member a few years ago. They were rated for 1000, or 1200 volts and work great.
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