large power supply replacement caps for crown micro-tech 1000 question(s)

Rex Aeterna

Rex Aeterna

Gigolo of Gigolos
i plan on replacing the power filter caps pretty soon on this amp. just want to know what is the possible largest cap i can effectively go to with no modification to the amp at all? i just plan on replacing them since the amp is over 30yrs old by now(made in 1985) and just would like to do it to increase life-span and peace of mind for another possible 25-30years. i wouldn't usually do this but, it is a defiant keeper in my stable so would like to treat it a bit.

seems like nichicon is only one that makes the larger caps but, are more pricey than i thought so i know just replacing these two guys is gonna be expensive. the original caps are 100v 10,000uf and was thinking of getting a pair of 160v 33,000uf caps from digi-key. i believe increasing the voltage and capacitance is ok from what i read... i just don't want to go too large since while there is good bit of space inside i'm just concerned on the diameter size limit. i think 90mm is thickest it can go inside...

i just want to get an idea on limitations i have and advice will be much appreciated it. i have forgotten a lot of stuff over the years so, while i remember some things, i forgotten lot of other things. i am even going to have a local tech i known for years to replace the caps for me out of comfort of knowing someone with over 30 years of experience is gonna handle it for me.

everything else was replaced in the amp it seemed when i looked inside. guess it was recently serviced before i bought it from a local guy i met cause, all transistors and everything else is brand new and marked. just the power filter caps was left a lone so, i am thinking of replacing them in the near future myself. anyhoo, enough babbling and any advice is welcome and of course very much appreciated. thank you.
 
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I am not familiar with the Crown micro-tech 1000, but in general these are the considerations.

I would say even going to 15,000µF is a stretch, and increasing the voltage and/or capacitance isn't going to, as you say...

Rex Aeterna said:
and just would like to do it to increase life-span and peace of mind for another possible 25-30 years.
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Increasing capacitance will stress the power switch and the rectifiers, maybe even the transformer too with the over 3 times increase you are planning. You can increase capacitance to a degree with some benefit, but unless you crank the volume you are never going to hear the benefit. You should know that the transformer is the real limiting factor here.

Increasing the voltage rating will negate some of that capacitance increase, with no benefit, other than a larger can size - to fill-out existing clamps perhaps. Ideally, capacitor voltage should be chosen so that the voltage applied is around 80% of that voltage rating - so if it has 80 volts applied - 100 volts is a good rating.

If you want to give the Crown a treat, change for same voltage, same capacitance, top quality replacement capacitors.

Don't take my word for it, talk with AK member Kevzep who has been working on Crown amplifiers for years. @kevzep
 
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Hyperion said:
I am not familiar with the Crown micro-tech 1000, but in general these are the considerations.

I would say even going to 15,000µF is a stretch, and increasing the voltage and/or capacitance isn't going to, as you say...



Increasing capacitance will stress the power switch and the rectifiers, maybe even the transformer too with the over 3 times increase you are planning. You can increase capacitance to a degree with some benefit, but unless you crank the volume you are never going to hear the benefit. You should know that the transformer is the real limiting factor here.

Increasing the voltage rating will negate some of that capacitance increase, with no benefit, other than a larger can size - to fill-out existing clamps perhaps. Ideally, capacitor voltage should be chosen so that the voltage applied is around 80% of that voltage rating - so if it has 80 volts applied - 100 volts is a good rating.

If you want to give the Crown a treat, change for same voltage, same capacitance, top quality replacement capacitors.
Click to expand...


thank you for your reply. thank you for the info. i did not know that. i really appreciate it. i did find some 100v caps but, from what you said is 160v too much? i was thinking of this as a main amp but, would sometimes in near future try it as a subwoofer amp since it is stable down to nominal 1ohm loads in parallel mono so guess, only way see benefit of slight uf increase is from those applications. but, if even if 15,000uf is too much a stress i would try to stick to correct value of course.

what caps would be good to choose from. is nichicon only one who supplies the larger voltage and capacitance caps?
 
damacman said:
Hmmm ... Going that large could be detrimental to the power switch.
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like said, i forgot lot of things since i been away from audio for years. it's like learning all over again so, i will admit i can be retarded a lot of times and very slow when it comes to stuff. that why i always think best to ask others with far more experience and knowledge to help me out.
 
Nichicon make extremely good capacitors, (this is the make I was thinking of) which can be obtained from Michael Percy Audio (among others). You need to check the size of any replacement you select, as I see the Crown Micro-Tech 1000 has quite a slim case, and the Nichicons tend to be quite large. There are 2 quality grades of Nichicon large can capacitors 'Gold Tune' and 'Super Through' - with 'Super Through' being the best.

They are expensive, take your time, get some other opinions - my opinion isn't the only game in town ;)
 
Hyperion said:
Nichicon make extremely good capacitors, (this is the make I was thinking of) which can be obtained from Michael Percy Audio (among others). You need to check the size of any replacement you select, as I see the Crown Micro-Tech 1000 has quite a slim case, and the Nichicons tend to be quite large. There are 2 quality grades of Nichicon large can capacitors 'Gold Tune' and 'Super Through' - with 'Super Through' being the best.

They are expensive, take your time, get some other opinions - my opinion isn't the only game in town ;)
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you are very helpful and very much appreciate it. i actually do remember hearing bout those caps and other names i have forgotten when i downloaded his catalog. they don't have it in 10k uf but, 15k uf it seems for 100v caps. measurements don't seem bad looking at them and have good feeling they will defiantly fit inside. the original caps are pretty large themselves and has good couple more inches of free space length wise. i'm just not good with depth but, the super through depth is 76mm so it is actually smaller than i thought so, it should fit fine i guess. depth is only concern i have but, i think the original caps inside are bout 90mm or so but, could be completely off. they just seem pretty thick.

i will defiantly wait on more opinions though but, really appreciate your opinion and advice. been very helpful and very much appreciate it.
 
If I ever get around to reconditioning my pair of MT1200s, I will check the rail voltage and decide if higher voltage rating is necessary but use standard caps of similar capacity.
 
Hyperion said:
I am not familiar with the Crown micro-tech 1000, but in general these are the considerations.

I would say even going to 15,000µF is a stretch, and increasing the voltage and/or capacitance isn't going to, as you say...



Increasing capacitance will stress the power switch and the rectifiers, maybe even the transformer too with the over 3 times increase you are planning. You can increase capacitance to a degree with some benefit, but unless you crank the volume you are never going to hear the benefit. You should know that the transformer is the real limiting factor here.

Increasing the voltage rating will negate some of that capacitance increase, with no benefit, other than a larger can size - to fill-out existing clamps perhaps. Ideally, capacitor voltage should be chosen so that the voltage applied is around 80% of that voltage rating - so if it has 80 volts applied - 100 volts is a good rating.

If you want to give the Crown a treat, change for same voltage, same capacitance, top quality replacement capacitors.

Don't take my word for it, talk with AK member Kevzep who has been working on Crown amplifiers for years. @kevzep
Click to expand...


just saw this morning and contacted him for advice. very much appreciate it.. i was looking at the microtech 1200 service manual(same as 1000 that been told by pretty much everywhere i read and asked) and it seems it uses a 35 amp 400v bridge-rectifier.... don't know what that means but, it seems it means it'll be ok with a slight capacitance increase with the amp,right?
 
I disagree with the group on this one. I always increase capacitance when I change PS caps. Keep voltage the same or higher. I'd go at least 15K capacitance, just make sure physical size is ok and will fit and the attachment method is same (screw top, then get screw top, etc). I also use power strips to turn my amps on and off so no worries for power switch, it's always in make position. I would do this whether stock caps or upsized, power switches last forever this way.

The rectifier is the only thing you have to be concerned with then and I've never had one fail in multiple amp rebuilds. If you were concerned on this then that is a cheap fix and you can buy what you need quite cheap.
 
Gibsonian said:
I disagree with the group on this one. I always increase capacitance when I change PS caps. Keep voltage the same or higher. I'd go at least 15K capacitance, just make sure physical size is ok and will fit and the attachment method is same (screw top, then get screw top, etc). I also use power strips to turn my amps on and off so no worries for power switch, it's always in make position. I would do this whether stock caps or upsized, power switches last forever this way.

The rectifier is the only thing you have to be concerned with then and I've never had one fail in multiple amp rebuilds. If you were concerned on this then that is a cheap fix and you can buy what you need quite cheap.
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alrighty then. i was just gonna go with the computer grade types cause seems the other audio grade caps from nichicon and others are lugs. the crown caps are screw terminal and only caps i found with screw terminals is other couple brands of computer grade caps and nichicon computer grade caps. if voltage was increase, what is exactly a safe number to go with as a guess or good estimate with no issues? as mention the crown uses a 35a 400v rectifier..don't know exactly what that means and the limit it puts me at though. really appreciate your opinion and advice. very much appreciate it.
 
Crown has been in the reliable amp game for a long time.

Rather than just picking a bigger number, I suggest measuring the actual voltage on the caps for an informed decision if a change in that regard is even necessary.
 
Pretty robust rectifier there. No worries there! No risk to going higher in voltage, just make sure you stay at or higher then the original caps voltage. I'd go 15-20K capacitance and call her done as long as they fit in the space you have creating no issues for your reassembly.
 
whoaru99 said:
Crown has been in the reliable amp game for a long time.

Rather than just picking a bigger number, I suggest measuring the actual voltage on the caps for an informed decision if a change in that regard is even necessary.
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i know. i was asking out of curiosity. i am going to stay at the 100v rating it has for the caps of the original. might increase the capacitance a bit maybe but, still reading up and learning some things. still deciding.
 
Gibsonian said:
Pretty robust rectifier there. No worries there! No risk to going higher in voltage, just make sure you stay at or higher then the original caps voltage. I'd go 15-20K capacitance and call her done as long as they fit in the space you have creating no issues for your reassembly.
Click to expand...

alrighty then. i just wanted to make sure everything would be a-ok on my part. i'm gonna start browsing around a bit more before deciding but. probably gonna stick with nichicon computer grade caps since besides others they're screw terminals. really appreciate the advice and your opinion here. very much appreciate the help.
 
Since you don't know the size for sure, just going by ratings, there are a couple Epcos/TDK caps that look about right to me. 100V, 10,000uF, 12000h@85c. About $22 each. There are some 15,000uf similar rating for about $5 more but they're longer than the 90mm mentioned.

(DigiKey)
 
whoaru99 said:
Since you don't know the size for sure, just going by ratings, there are a couple Epcos/TDK caps that look about right to me. 100V, 10,000uF, 12000h@85c. About $22 each. There are some 15,000uf similar rating for about $5 more but they're longer than the 90mm mentioned.

(DigiKey)
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the 10000uf caps i measured at around 5.5'' which is bout 140mm in length. there is some room in the case for couple more inches but, of course i want stay close as possible. depth i have no idea on how to measure but, supposedly i think from just guessing and reading, that 90mm is largest i can go depth size since going by height estimate itself as 3.54'' but, like i said i have no idea on the idea depth. i just measured width and changed it to circumference which around 5.5'' around since they're bout 2'' wide. the mt1200 uses the same 10,000uf caps as the 1000 does so if can, if not too much trouble and have time if can be possible to measure depth. i have no idea on how to do that personally. i just know the length of the caps themselves. it will be much appreciated. i also appreciate the advice on the cap suggestion. will defiantly look at them.
 
I would think you should be able to find larger capacitance caps than original at same voltage that are would fit where your old caps do. I haven't looked but almost all electrolytics are now smaller then they were back in the 80's.
 
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