Bipolar capacitors can not be used as output capacitors in ST120.
it need to store energy at the center tap to provide power for the other half cycle.
Im looking for some capacitors to upgrade mine.
it need to store energy at the center tap to provide power for the other half cycle.
Im looking for some capacitors to upgrade mine.
"Bipolar capacitors can not be used as output capacitors in ST120."
Sure you can. Just like you could use a big honkin' film capacitor instead.
It would only need a 100V peak voltage rating. It's just a DC blocking capacitor.
Sure you can. Just like you could use a big honkin' film capacitor instead.
It would only need a 100V peak voltage rating. It's just a DC blocking capacitor.
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rayma, do you mind providing some photos of O.T.L. amps that use bipolar caps for outputs, or any website for me to find, so that I can learn.
thanks
thanks
I did not say there WERE such commercial amplifiers, I said there COULD be.
There is no technical reason why not. Anyone can build one easily if desired.
Of course, an OTL amp with bipolar power supplies REQUIRES a bipolar
output coupling capacitor, although I don't know of such an amp that is
commercially available at present.
In fact, for many years Electronic Concepts Inc. (a military contractor),
has manufactured film capacitors that are intended to replace electrolytic types
in critical applications. I have used these parts for decades in place of electrolytics.
And yes, they are non-polar.
https://www.ecicaps.com/wp-content/uploads/UP37_full.pdf
There is no technical reason why not. Anyone can build one easily if desired.
Of course, an OTL amp with bipolar power supplies REQUIRES a bipolar
output coupling capacitor, although I don't know of such an amp that is
commercially available at present.
In fact, for many years Electronic Concepts Inc. (a military contractor),
has manufactured film capacitors that are intended to replace electrolytic types
in critical applications. I have used these parts for decades in place of electrolytics.
And yes, they are non-polar.
https://www.ecicaps.com/wp-content/uploads/UP37_full.pdf
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I need facts that I can follow.
its easier to say than done.
If there were no such amps else where then I wouldn't try.
My ST120s is for home use, no military grade caps needed,
Thanks
its easier to say than done.
If there were no such amps else where then I wouldn't try.
My ST120s is for home use, no military grade caps needed,
Thanks
A bipolar costs twice as much.
The Dyna has a reliable predictable DC voltage on its output. A uni-polar will do the job. Why pay more?
The Dyna has a reliable predictable DC voltage on its output. A uni-polar will do the job. Why pay more?
That's very interesting. What you described is what I would expect to see for hiifi. When I went to my first hifi show, I was a bit surprised to see how many amps had massive capacitors on the output. Some of these capacitors were the size of my forearm.
Sadly though, I also saw plenty of amps that just had some 5 dollar 3000uf nichicon stuck on the binding posts. I never questioned it because none of the amps impressed me enough to care.
And yes, I have a bad habit of saying DC coupled when I should be saying direct coupled.
I don't know where you are located or how old these SS amplifier designs are to comment on your evidence. What are these models that you see at audio shows? i.e. are they commercial products, high end specials, hand built or amateur designs, prototypes or "to order only" products perhaps?
Anyway, look at the brands and models from many countries considered daily here. Only the very old types, usually because of their nostalgic following, are capacitor coupled to the speaker load and today, I don't see any capacitor coupled types there at all. Go through today's thread titles in this SS amplifier forum and see for yourself. No large scale, commercial manufacturers market these anymore, nor have they been marketed in western countries for 40 years or so.
So what are you referring to? Perhaps old hobby magazine designs, relics from the past or more recent copies of them, maybe those following early Philips designs for hobbyists or JLH's designs, from up to fifty years ago? Are there more recent developments on a small scale, such as we don't often see here?
Also, bear in mind that it's generally cheaper to "chuck in a servo circuit" than to add a big, high quality electrolytic to the build. But why would we opt for a more expensive yet technically inferior design anyway? Perhaps its also because you can avoid fitting a speaker relay and just accept that the amplifier will likely thump or make other noises when powering on or off?
Anyway, look at the brands and models from many countries considered daily here. Only the very old types, usually because of their nostalgic following, are capacitor coupled to the speaker load and today, I don't see any capacitor coupled types there at all. Go through today's thread titles in this SS amplifier forum and see for yourself. No large scale, commercial manufacturers market these anymore, nor have they been marketed in western countries for 40 years or so.
So what are you referring to? Perhaps old hobby magazine designs, relics from the past or more recent copies of them, maybe those following early Philips designs for hobbyists or JLH's designs, from up to fifty years ago? Are there more recent developments on a small scale, such as we don't often see here?
Also, bear in mind that it's generally cheaper to "chuck in a servo circuit" than to add a big, high quality electrolytic to the build. But why would we opt for a more expensive yet technically inferior design anyway? Perhaps its also because you can avoid fitting a speaker relay and just accept that the amplifier will likely thump or make other noises when powering on or off?
Some of the (vintage) highly regarded amps (and receivers) were cap-coupled, and even today sought after.
The Harman Kardon's, The Dynacos, and the famous Armstrong amps too.
Asides from not really being "super wattage" amps that the fanatics seem to embrace, those older cap amps sound quite nicely to even the trained ear.
I certainly see nothing wrong with them.
The Harman Kardon's, The Dynacos, and the famous Armstrong amps too.
Asides from not really being "super wattage" amps that the fanatics seem to embrace, those older cap amps sound quite nicely to even the trained ear.
I certainly see nothing wrong with them.
I have just tested with my other OTL amp with bipolar caps used as output capacitor.
It works fine, can't see any problem.
But with same capacitance I need four caps to make one,
or two twice as big one to make.
It is at lease 4 times the cost to replace one.
Thank you PRR for pointing out the high cost in doing so.
Thank you rayma, you let me know Bipolar caps can be used as output caps.
again thanks to all
regards,
Alexchoi
It works fine, can't see any problem.
But with same capacitance I need four caps to make one,
or two twice as big one to make.
It is at lease 4 times the cost to replace one.
Thank you PRR for pointing out the high cost in doing so.
Thank you rayma, you let me know Bipolar caps can be used as output caps.
again thanks to all
regards,
Alexchoi
If a sealed speaker has a high Q-factor like 1, because of small enclosure or high Q driver, a big series capacitor of 800 to 1800uF (driver dependent) can completely linearize and extend half an octave on the bottom. No larger amp needed.
With a single supply amp only one cap needs to be changed to the desired value or maybe has it already.
as mentioned a bipolar output needs 4 pcs with this value.
With a single supply amp only one cap needs to be changed to the desired value or maybe has it already.
as mentioned a bipolar output needs 4 pcs with this value.
Direct coupled transistor amps can sound very good. They can get HD down to .000x%, which is a totally inaudible advantage on speakers compared to .0x% HD.
When trouble occurs like pulling the 1/4 phone plug to speaker out 1/4" (to create a short) or a bad solder joint in a home built amp, direct connect can fry your $600 speaker in a second. Also can blow all output transistors at $5 each plus maybe 128 other parts. I have purchased on ebay several clean dogs of power amps from the 1990's with bad solder joints installed at the factory. Looked great, passed QA one time.
Integrated sound companies like Sony Behringer etc love it when the product fries the speaker. Rings the cash register twice or 3 times instead of one.
Protection circuits that are useless cost about $5. Contain a $3 AC rated relay that won't break a 1000 amp DC arc, and a dozen other parts
Protection circuits that are competent have a $40 relay and a dozen other parts. Try finding one on ebay. Cheapest way to buy the competent relay is in a blown PA amp from Yamaha Crown QSC or Peavey.
Nfet protection circuits are simpler but are not found in commerical products for some reason. Maybe because they don't work? Work only under special conditions? Look for an nfet protector in a class AB Yamaha Crown QSC or Peavey PA amp. Not there.
Single supply amps protect the $600 speaker with a $3 3300 uf to 4700 uf polar capacitor. Has to be past service life to fail. Film capacitors of that size are several hundred dollars. I tried back to back 10000 uf polar capacitors on output of the CS800s. it sounded funny at 1 W. Crossing zero causeed chemical events.
I find my modified (djoffe idle bias control, better heat sinks ) dynaco ST120 with speaker cap sounds exactly the same @ 1 - 70 W on my $600 (new) speaker as my repaired CS800s with no caps in the sound path. Latter advertised at .02% HD @ 240 W.
One advantage of single supply amps, 90's transformers without a center tap cost about half what new ones do. Come in E-core that don't trap the heat the way toroids held down by a washer do. E-core transformers don't need soft start and don't need lightning spike protection on the front end.
When trouble occurs like pulling the 1/4 phone plug to speaker out 1/4" (to create a short) or a bad solder joint in a home built amp, direct connect can fry your $600 speaker in a second. Also can blow all output transistors at $5 each plus maybe 128 other parts. I have purchased on ebay several clean dogs of power amps from the 1990's with bad solder joints installed at the factory. Looked great, passed QA one time.
Integrated sound companies like Sony Behringer etc love it when the product fries the speaker. Rings the cash register twice or 3 times instead of one.
Protection circuits that are useless cost about $5. Contain a $3 AC rated relay that won't break a 1000 amp DC arc, and a dozen other parts
Protection circuits that are competent have a $40 relay and a dozen other parts. Try finding one on ebay. Cheapest way to buy the competent relay is in a blown PA amp from Yamaha Crown QSC or Peavey.
Nfet protection circuits are simpler but are not found in commerical products for some reason. Maybe because they don't work? Work only under special conditions? Look for an nfet protector in a class AB Yamaha Crown QSC or Peavey PA amp. Not there.
Single supply amps protect the $600 speaker with a $3 3300 uf to 4700 uf polar capacitor. Has to be past service life to fail. Film capacitors of that size are several hundred dollars. I tried back to back 10000 uf polar capacitors on output of the CS800s. it sounded funny at 1 W. Crossing zero causeed chemical events.
I find my modified (djoffe idle bias control, better heat sinks ) dynaco ST120 with speaker cap sounds exactly the same @ 1 - 70 W on my $600 (new) speaker as my repaired CS800s with no caps in the sound path. Latter advertised at .02% HD @ 240 W.
One advantage of single supply amps, 90's transformers without a center tap cost about half what new ones do. Come in E-core that don't trap the heat the way toroids held down by a washer do. E-core transformers don't need soft start and don't need lightning spike protection on the front end.
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Autotransformer taps allow you to align and adjust the signal level in the playback bands. Impedance matching is performed.
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Like this one? These would allow decent bass response even with a 2 ohm load.
Attachments
2015 actually. I'm still in my 20s. 😛
If you guys tell me that cap coupled outputs are pretty rare, then so be it. It just means that I have had pretty unusual experiences up until now. I am actually happy I am wrong because I never liked any of the cap coupled amps anyways.