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Capacitor life

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Whats the life span of capacitors in our equipment. I am asking because it seems that the top end is rolled off on my speakers and they are pushing 24 years old. The caps are REL-CAPS PPT series. What to replace them with?? Suggestions!

 

MAK

 

 

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1 minute ago, Ralf11 said:

there is a wiki on capacitor rot - you'll need a manf. date for your gear

The last date of manufacture was 1996 for this line of Genesis speakers.

 

MAK

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23 minutes ago, RickyV said:


Are you sure it is the speakers capacitors that are failing and not the driver itself. usually the drivers cone surround are first to go. They dry out and become harder and less flexible. This of course influences the parameters of the driver. You can carefully touch the surround with your fingertip. You can do the same with the tweeter, if dome tweeter, extra careful and only a tiny bit. See if still flexible.

Of cause 24 year is old for speakers and even capacitors age so it is possible. The sound of a speaker is for a good deal determined by its capacitors so do not buy industrial caps they will sound industrial. 
Capacitors brands: Audyn Cap Plus is good, Jantzen Capacitors, Mundorf Capacitors, ClarityCap Capacitors, and many more. Just replaced them with the correct values.

 

The Mid panel is either the 48" carver or BG48 ribbon. There is no surround on this. The tweeters do not have surrounds on them either. This is a 4 column system with separate bass and Mid/Hi panels. Bass columns are servo driven. I am considering Mundorf Supreme's.

 

 

 

crossover.jpeg

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3 minutes ago, Richard Dale said:

Are you sure that REL-CAPS PPT caps are electrolytic? It would seem strange to me be fit a high quality speaker with cross overs that might fail after only 20 years.

 

 

Richard,

 

PPT are film caps.

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1 minute ago, gmgraves said:

Mostly, capacitor life is tied to electrolytics. Crossover and other small signal, non-polarized capacitors live much longer. I recently refurbished a Stromberg-Carlson console radio that’s over 70 years old (1948), and while the electrolytics in the power supply were long past even being capacitors, the paper and foil small signal capacitors (mostly between 0.22 and 0.47 mFd. types with one 0.68) which were bee’s wax dipped, were still good and worked perfectly. Of course, I can’t vouch that they were still their original, marked values, but they were close enough not to affect the radio’s AM, FM, Short Wave or audio performance! This console was quite interesting. The woofer was horn loaded into an acoustic labyrinth type folded horn, and had a two inch speaker as a tweeter! When I finished retubing it, and fixing the power supply, it sounded excellent (for a “brown goods” console radio. I bet it was very expensive when new).

It had a 10 -12 Watt amp using push-pull 6V6 output tubes and the radio had 4 FM IF stages and 6 AM/short wave IFs!

 

Well I know you are beyond my knowledge with this stuff. I can solder and paint by numbers though!

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1 minute ago, Richard Dale said:

Could it just as easily be the ribbons ageing? It is obviously an expensive speaker and just going in and attacking the crossovers without nailing down exactly what the problem is, seems the wrong way to go about it to me.

 

Richard,

There is only 1 ribbon for each side. 15 tweeters for each panel. The ribbon is for the Mid range only. I am trying to nail down the issue as you describe without replacing everything like a shade tree mechanic. What has been suggested is that if I have to de-solder the caps to test with a meter, I may as well replace them. What do you suggest if you hear a rolled off top end??

 

MAK

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1 minute ago, RickyV said:

In the picture I think I see a rotary switch and a potentiometer, correct? What those for? Any relevance to the high tones?

3 position rotary switch for the midrange; Low, medium and high. Potentiometer for the 3 rear tweeters and it checks out good. 0.4 to 5.4 ohms. No dead spots or rough feeling.

 

 

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1 hour ago, 4est said:

If your speakers are losing highs, it is not likely these. PM Superdad here, and he can give you the low down. These are a film and foil (polypropylene and tin?) capacitor, and they do not age like an electrolytic one. These are also not bad or hand made parts. You would have found these in ARC equipment IIRC. Sure there are better parts available, but they will cost you. It is possibly the problem, but unlikely IMO. To my knowledge these are still made under the AudioCap name.

 

There is a Vishay resistor I'll test and see if it still specs out. 

 

MAK

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10 hours ago, Archimago said:

 

Hmmm, @Racerxnet, I'm thinking first things first before replacing stuff... Have you done some measurements on those speakers' frequency responses and maybe compared the the pair to see whether one is worse than the other?

 

This will obviously also give you a baseline to compare if you did proceed to replace caps... Last thing you'd want to do is go in blind and perhaps make things worse!

 

 

Gary Koh wrote a reply some time ago regarding the bass columns accelerator causing a plus minus 18db response from 18 to 90hz. This may be the cause of the issue. I'll measure this soon. I have not done anything so far but investigate where the problem may be. Reliable Cap is going to send me the specs that Genesis requested for cap values. Thanks to everyone on this. 

 

Mark

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Can any of you guys identify the rotary selector switch used for the mid range setting. I am looking for a direct replacement before having to re-engineer the switch to the board. Upper left side of pic. The output to the midrange panel  is intermittent when wiggling it. 

 

 

crossover.thumb.jpeg.1af9b50979376da5fe6150f554719a5d.jpeg

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1 hour ago, sandyk said:

I presume that you have tried squirting some Isopropyl Alcohol into it ?

 

This is a case where the pins soldered to the board are possibly broke. I won't know until I un-solder the switch, but at that point I'd rather just replace with new. I hope that there may be a part number on the top side. 

 

MAK

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1 minute ago, fas42 said:

This is a killer giveaway as to what may be degrading the SQ - the ol' weakest link in the chain will always determine the strength of the whole ...

 

Do you know where I can find the single deck rotary switch? 3 position, right angle, through hole. That's the question. 

 

MAK

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21 minutes ago, fas42 said:

 

Looking around , I can see your problem ... why don't you speak to Genesis, ask them where they sourced them?

 

Personally, I would hard wire the desired setting, job done ...

 

Whats my problem? I already have a reply to Gary Koh for the switch. If he cannot source it I have to improvise. Hard wiring it is a poor choice. What frequency should it be wired to? How can I select a different frequency if hard wired? Is there a reason it needs to be hard wired?

 

Do you really think your position regarding the matter is a better engineered product that what Arnie Nudell and Paul McGowan have provided? I'd need hard data from you to find any credibility from what you state. What I do want is to identify the switch. It's place in the crossover network is transparent if properly speced and implemented.

 

MAK

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1 minute ago, tmtomh said:

 

There's some very good info in this thread, but with respect I would suggest you head over to AudioKarma.org - that place is filled with people who have years, sometimes decades, of rebuilding and repairing every aspect of speakers and can give pretty solid advice as to what to test first and what the pros and cons are of cleaning a switch, trying to repair the switch, sourcing a replacement for a switch, rebuilding a crossover, and so on. AudioKarma is not my go-to for knowledge on modern digital audio or for a culture dedicated to measuring equipment performance. But when it comes to using measurements to diagnose equipment problems and work on repairs, and when it comes to advice on how to go about determining what to repair and what to leave alone, I find the folks there to be among the most valuable on the internet.

 

 

 

Don't go down the Frank rabbit hole. It never ends.

 

I have already determined with a meter that the switch is bad. I'd clean the switch, but broken pins are another matter. I could solder new leads onto the pins and give it a go if all else failed. Thanks for the heads up for the other web site and I will post if Gary cannot provide 2 new ones. Digikey has hundreds to choose from and I need to remove it to test the pinout. 

 

Thanks,

 

MAK

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Thanks to everyone on this small project. I was able to identify the wafer switch and get a replacement. New Rel-caps, switch and NP 300uf x 2, 100v, 5% caps. 

 

Mark

 

NewSwitch.thumb.jpeg.560f01dc818625b52d0f9f9a113f8645.jpeg

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23 minutes ago, beetlemania said:

I didn’t read every post in this thread so maybe I’m repeating information . . . 
 

PPT is a polystyrene film cap. It is a very high quality type and should last a very long time. Why does “hand made” make a difference?

 

Electrolytics are caps that will drift with time, say 15-20 years.

 

 I would be inclined to leave PPT type in unless you want to play with other caps (caps do sound different). If you have any electrolytics (looks like two electrolytics on that board) of that age I would definitely replace those, and with a good film cap if available in the correct capacitance.

 

I never said they were hand made and aware of Rel-caps reputation. With the cost of replacement speakers I will only replace parts that are of the same brand/value as original if possible.

 

The speakers were made around 1996 or so from when Arnie Nudell left Infinity, and started the Genesis brand in Colorado. The caps are old and I am updating the crossover with new parts while available. I'm not interested in changing the tonal qualities. The wafer switch was bad and had intermittent contact.

 

The original Culver 600uf 100v 5% cap was no longer available, so I piggybacked 2 x 300uf 100v 5% NP caps as seen. The new wafer switch installed, and new Rel caps as well.

 

The speakers are 25 year old. My cost per side is around $250.00. Cheap enough to do ail of the components on both sides of the crossovers. They will last another 25 years possibly.

 

Mark

 

 

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