@hickamore it sounds like you just really wanted a new amp. I totally get that.
It's none of them, it's a Hitachi, one of the first FET amps, sounds like tubes, it's huge, and is 60lbs. Tested the power caps several months ago, they were all good. But just measured the bias last month and the right channel is a little off 5%, left Chanel was perfect. Will adjust it next time it get pulled out of the rack for cleaning.
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@mswale Too late, already sold and replaced. Oh, well. I was already considering an upgrade. Lucky you on a 50-year amp. What is it, Crown? Early ARC? An amp like that would be a conversation piece if you started a thread on the subject in this forum.
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Clean it, get the bias adjusted, and measure the power caps.
My amp is 50 years old, still 100% stock inside.
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My guess would be one or all. Power switches build up carbon from arching and become resistive after decades. Electrolytic power supply capacitors, final stage driver transistors, new output transistors.
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I have a Denon PMA-757 integrated amp from 1985 that's still going strong. I had it serviced a few years ago, cleaning, replacing a few bulbs but that's it. Sounds great. It's powering a pair of Canton Karat 200s from 1986.
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Lots of words of wisdom here.
Well dine.
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@hickamore. God willing you'll live a lot longer! 😊
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@ozzy62 Appreciate the reassurance on Coda. Though the Parasound really was losing its grip. I never upgrade without provocation. Too many other costly priorities in life.
@stringreen LOL. Maybe I should have bought Ayre way back when.
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my 20 year amp went out about a year ago.....sent it back to Ayre for a look-see with request to make it as perfect as you can. They replaced a fuse and sent it back.
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Swapping a parasound amp for a coda amp might have as much (or more) to do with the Coda just being a better designed and built amp than the Parasound.
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@jimmyblues Guess I simply took the amp for granted until after the warranty had expired. But can't complain after 11 trouble-free years. Recapping may give it a new lease on life -- in someone else's system. No point in my keeping it given my age plus a fresh ten-year warranty on a new amp that may well outlive me.
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@8th-note Not surprising what logistical problems you would have with repair or resale at the old monster Krell level. Given your good fortune with repair, sounds like a lifetime amp and good investment decades ago.
I will definitely advise buyers this is original condition, no caps replaced as yet.
Just bought a 45-lb Coda that checks my boxes, so at my age fuure equipment repair/upgrade should be easily manageable. (Well, except for a monster dual-firing Tannoy sub that I won't keep and needs the new amp plate installed before resale . . .)
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Depending on the model of amp it could be worth it to get it repaired. For example, I have a Krell KSA 300S from the mid 90's that I bought new. It worked fine for over 20 years and then died with a puff of smoke. I was lucky that there was a qualified repair technician (Gig Harbor Audio near Tacoma Washington) that was within a couple hundred miles. They were able to send a key module (output transistors I think) to Krell in Connecticut for repair and replace the capacitors themselves. This avoided shipping the whole unit from Washington to Connecticut which would have been nearly $2000 (this amp weighs 185 lbs without packaging).
The total cost of the repair was about $3000 and the amp is worth $4k to 5k on the usesd market so it was an easy decision. It's driving a very difficult load (Thiel CS6) and to replace this amp with a new one of similar capability would have been tens of thousands of dollars.
Hopefully anyone who buys a 20+ year old SS amp knows that the capacitors will need to be replaced. If you sell the amp make sure that you state it is in original condition. The amp is likely to fail soon and if it was me I would clearly state that the amp needs service and the buyer needs to take that into account.
The last thing I'll mention is that it is hard to get rid of a monster vintage amp because if it weighs over 150 lbs with packaging you have to ship it LTL which is very expensive. Also, if you don't have the original packaging you have to build a crate that accomodates a fork lift which is surprisingly costly, especially if you have it done professionally. If you don't go to extreme measures to package the amp for shipping you can pretty much guarantee that it will arive damaged. Most people selling equipment like this require the buyer to pick it up so if you are in the sticks you'll need to take that into account.
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@lynn_olson Mine is a case of gradual relaxation on driver grip, most noticeable in the bass. I was actually enjoying the bottom end end harmonic distortion, but when a notorious high amplitude signal in the low impedance frequency range threatened to blow the left speaker, I knew the time had come. Being impatient, and having no repair shops anywhere near, and also curious about the new iteration of Coda S5.5, I simply switched it in for the Parasound, quickly heard the difference, then posted this question.
@ audioman58, @chenry I'm not worried about the speakers, given that a new amp quickly removed their flabbiness. They are a little newer than the amp and now sound fully restored. So I now feel confident that their useful life without repair will exceed my own.
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Years ago I read an article whose author stated that as a rule of thumb, capacitors on solid state power amplifiers should be replaced every decade or so. This is even more pertinent when the amplifiers receive a lot of use. 👍
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The speaker caps are probably OK if the new amp is working fine with them.Speaker crossover caps will go bad, but not as quickly as amplifier caps, 30-40 years. If you were using vintage speakers made from 1950s to 1970s, then replacing the crossover caps would make sense.
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In your loudspeakers most likely the coupling capacitors ,I have been upgrading Xovers for years ,stock Xovers are in most cases average at best to save $$
upgrade-these capacitors and your speakers will sound better then before
as long as the drivers are still in good shape.
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Transistors don’t age. They keep working, staying within spec, and one day, fail without any warning. When that happens, as often as not, several other parts burn out as well (typically resistors). In other words, they work fine until they don’t.
The secret to long life for a transistor is keeping the transistor die cool. That’s a function of heat-sink design (more is better) and keeping the component well-ventilated.
The parts that do gradually degrade with time are electrolytic capacitors and paper-and-oil capacitors (not generally seen in modern equipment). Mylar and polypropylene caps basically last forever, along with adequately rated resistors.
So if you want your transistor gear to last forever, replace all the electrolytics every ten to twenty years, and get a small fan to keep it as cool as possible. Everything else should be fine.
Now if the circuit board design is really bad, with hot resistors next to capacitors, and poor quality solder joints, yes, it can fail in a few years, and can be very tedious to repair if all the parts are jammed together.
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Wish someone around here did. I live in the wilderness. Where are you?
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we repair/upgrade/modify audio components all day long!
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@bigkidz Good news indeed. Much appreciated.
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Yes parts especially capacitors in the power supply section can go bad and need replacement. Good news, there are probably better supply caps now and they will improve the sound of your equipment.
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@chenry Makes total sense and no doubt you are right. Thanks, I will look into that.
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If you kept it as long as you did, it can’t have been bad. It might be worthwhile having the unit serviced and bad caps replaced along with anything else needing replacing, As a second system amplifier it might be a familiar and welcome value, it seems as if it was very well made to have lasted so long.
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@chenry, @noromance Never had it checked out, nothing replaced, but warranty had expired before I noticed the slippage in performance, and the thing weighs a ton and is long discontinued. Of course you must be right. Guess I will sell it with a note to check capacitors and/or use with 8ohm speakers until it dies. Thanks!
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What he said. Some open circuit (parallel) output transistors could also do this.
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Aging electrolytic capacitors. Have you had any replaced in the time of your ownership?
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