Hey all!
I've been assembling a ZKit 1 and I realised that I've used the wrong type of capacitors for power filtering.
The schematic calls for two polarised 20uf capacitors and I've used an unpolarised type (top right of the linked schematic, orange in the picture). The voltage rating is the same but I'm wondering if this will impact the performance? Any advice would be appreciated.
Schematic: https://www.decware.com/newsite/ZKIT1.pdf
Also if anyone has resources for safety procedures for testing and working with high voltage AC I'd really appreciate that.
I've been assembling a ZKit 1 and I realised that I've used the wrong type of capacitors for power filtering.
The schematic calls for two polarised 20uf capacitors and I've used an unpolarised type (top right of the linked schematic, orange in the picture). The voltage rating is the same but I'm wondering if this will impact the performance? Any advice would be appreciated.
Schematic: https://www.decware.com/newsite/ZKIT1.pdf
Also if anyone has resources for safety procedures for testing and working with high voltage AC I'd really appreciate that.
Hello,
As already mentioned , best to remove and replace . Not because a non polarised cap of 20uF could not do the job of a 20 uF polarised cap electronically speaking , but it is not the optimal part . For ripple smoothing a 20 uF non polarised cap is overly qualified . An electrolytic would be smaller cheaper , and a better option . Being a reasonably expensive item the non polarised cap is better placed in coupling roles or crossover filters .
So I would save it for something like that instead, and use it where you will get the best benefi.
Regards
Mil
As already mentioned , best to remove and replace . Not because a non polarised cap of 20uF could not do the job of a 20 uF polarised cap electronically speaking , but it is not the optimal part . For ripple smoothing a 20 uF non polarised cap is overly qualified . An electrolytic would be smaller cheaper , and a better option . Being a reasonably expensive item the non polarised cap is better placed in coupling roles or crossover filters .
So I would save it for something like that instead, and use it where you will get the best benefi.
Regards
Mil
Yup, those caps are wasted. Use in crossover instead.
Besides, you can get executed by accidentaly touching the wires sticking out.
Use proper part and be done with it.
Besides, you can get executed by accidentaly touching the wires sticking out.
Use proper part and be done with it.
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I do not understand exactly what you mean about the 20uf caps. The schematic shows them to be electrolytic and if I am correct you used film caps which is certainly fine if not better. At least most consider them better. I say you are good to go if this is the case. Personally, call me a heretic but sonically I have no problem with electrolytic capacitors. Nelson Pass even uses them on the output of the audio chain on some of his projects.
The one most important rule is one hand in pocket when working on a live high voltage amplifiers and this is not just talk. When testing one can just turn off amplifier when installing probes and then turn back on if first working with tube gear. If one thinks about it you do not want electrons flowing through your body from one finger on one had going out through the other hand. Make sense? This is the reason for one hand in pocket rule. If you accidently touch a live voltage with just one finger it will sting but not really do any damage.
Curious, where did you find the board you are building on?
The one most important rule is one hand in pocket when working on a live high voltage amplifiers and this is not just talk. When testing one can just turn off amplifier when installing probes and then turn back on if first working with tube gear. If one thinks about it you do not want electrons flowing through your body from one finger on one had going out through the other hand. Make sense? This is the reason for one hand in pocket rule. If you accidently touch a live voltage with just one finger it will sting but not really do any damage.
Curious, where did you find the board you are building on?
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This is usually done this way to increase the voltage rating of the two capacitors instead of using one 500 volt cap. To save money or in most cases to have a higher than 500V circuit that needs capacitors lets say 700v's. Install two 350V caps in series to have a 700v rating. That and the availability of 500V caps is small.
Well, a 10uf 630V Solen Fast cap is about the same price of a 20uF 250V Dayton Audio poly cap in the picture on post #1. Why double the space and price and the need of balancing resistors by using 2X20uF cap?
zant
As implied by others, there is nothing wrong with using these caps. At worst your amp will work as designed. The con is as you see they are big, and expensive by comparison. While a controversial topic, the amp may well sound better using the film caps. Since you already have paid for them and delt with the size, a reasonable approach would be to leave them in the circuit.
Wrt testing, treat this carefully. You never want to have the voltage run through your body. One hand to the other through the heart is the worst. Hence the one hand in pocket rule. It works. I do the following. First, probably overkill, I use an isolation transformer to power the project and a power bar with an on/off switch to make easy on and off with one hand. Then I use an alligator clip on the black probe. And to be triple safe, I make sure I am not in contact with ground, so work with shoes and a wood chair. Also make sure your work area is uncluttered so nothing will get knocked out of place when powered. So to test voltages, I clip one probe to a ground point on the circuit. Set your multimeter. Then one hand in pocket. With free hand turn on power. Use probe to check voltages. then turn off power. Then monitor voltages until everything settles back to zero. This may take a few minutes depending on size of drain resistors. Then disconnect from power. Double check all the caps are discharged before handling. Then and only then, pull your hand out of your pocket. It sounds like overkill. But the problem is it is easy to get involved in troubleshooting and forget this thing is still deadly and go to move something and get zapped.
The reason for the stacked 20uF caps is probably that 10uF electrolytics are not very common, so two 20 or 22uF caps in series are used. There's nothing wrong with using what you have, but as someone else mentioned it's inefficient and will make enclosing the PCB kind of clumsy. A 10uF/630v Solen would save a lot of space. Many people prefer film caps in their power supplies.
Very good reading about safety practices can be found at tubelab.com.
Read it until You learn it and then keep attention at how You are doing things, for example measuring live DC voltages.
Nasty shocks can happen when a man is not concentrated at what & how he is doing.
Read it until You learn it and then keep attention at how You are doing things, for example measuring live DC voltages.
Nasty shocks can happen when a man is not concentrated at what & how he is doing.
Information and the order form can be found here: https://www.decware.com/newsite/SE84CDIY.htm
Thanks everyone for the advice! I think that I am going to leave the caps in there for now since I have plenty of room in the hammond chassis that I bought. If I need those caps for some crossovers in the future I might replace both with a 10uf 600v solen fast cap as suggested.
The safety write up there was excellent. Thanks for that!