why a recap makes no difference

[roger2]

It's a good question and one I didn't fully investigate. I've had a about 4 or 5 1060s and they all exhibit the same overall response, so that is my benchmark. It was clearly intentional, and all the 1060 lovers out there hear exactly what we see in those plots. Thing is, I didn't run a preamplifier and power amplifier FR sweep individually- I ran it as an integrated amplifier, so I don't really know if it's a combination of both or what.

I can of course investigate it further at some stage as the amplifier is in use at his place as we speak, but I'll let him enjoy it for a while before I propose to take it back for more 'tests'

Thank you restorer-john. No need to feel any sort of obligation to investigate. I thought perhaps that you had already done so, or might have known the answer off hand. This is something that I have had an idle curiosity about after having done a comparison of my Kenwood KA-7100 vs my Sansui AU-X701 a while back.

Having believed, based on a few accounts here where various vintage amps were compared, that Kenwood amps generally had a more neutral voicing. And using my KA-7100 as the daily driver then (and still), had no reason to think otherwise. Until I compared it to the AU-X701. And I noticed that the KA-7100 had a bit more emphasis in the bass. Believing the AU-X701 to be a superior design (thus more neutral), my assumption is that the KA-7100 may have been intentionally voiced in a way similar to what you noted in the 1060.

Could be wrong about my assumptions of course. And none of this is urgent or pressing in any way. Just a curious thing to think about. Whether the amp makers back then did any voicing intentionally, and if so how was it implemented

 

[restorer-john]

Whether the amp makers back then did any voicing intentionally, and if so how was it implemented

My experience with literally many hundreds of amps and receivers is that the higher up the range (and cost), the flatter and more accurate they become.

The sales numbers were in the low-mid end. Sansuis, Pioneers, Kenwoods, Marantzs etc were competing in a fierce, price driven sales environment, and with features being much the same, they needed to stand out in the demonstrations (back when all the dealers had large switching comparators). People liked warmth, fatness in the bass and a lack of harshness in the top end. Primary source was of course vinyl- which has a poor bottom end to start with. So they tweaked them to sound the way they wanted to sell more.

Also, magazine reviews in the 70s when they did run FR plots, made them all look flat due to 5-10dB graticules on paper based plotters, reprinted in tiny scale in magazines. They were utterly meaningless. Now we can zoom in to 0.25dB scales with resolutions under 0.01dB. It's easy to see how bad they really were.

Also, doing plots at 1watt when the entire amplifier would change its characteristics as the volume went up. We should have been seeing full power FR plots in the 70s but nobody had the guts to do it. Once I link up my old audio lab to my network, I can put up plots for every amp I test on AK- right now I have to take pictures of the screen to post. (so old skool )

 

[fernarias]

yes,i am a little older and my hands are not as steady as they use to be,in fact i had to change to an auto TT,oh well,sucks to get old,lol.

not looking forward to that. Manual since 16 and I'm 52 now and hate using reading glasses to work on gear.
As for costs it's usually between 30 and 70 without mains(mains can be 6 to 30 each). Transistors are cheaper than that.

 

[Bill Ferris]

Very interesting thread, after reading through all.
What I`ve done on occasion in the past when considering a replacement of capacitors, other then outright failures on a piece of electronic gear brought to me for repair, or something that I bought, or was given used, is after getting the unit repaired & checked out and operational.
Is to power up the unit for hours idling (DBT protected, of course)while monitoring it`s 120 volt mains in current consumption, and if it appears higher then I think, or know it should be, I feel the power transformer, rectifier/s, and all PS related electrolytic capacitors for unusually elevated temperatures..
This is of course is after I have checked and set bias, and any other issues that might effect the idle current draw.

If any caps are having any leakage/ESR issues, that they will start becoming warm to the touch after a while, and will draw extra current, assuming they are not real close to a heat generating device, and in that case they should be suspect for replacement anyway IMHO/E.

I have refused to service audio gear brought to me, when the customer has asked me to only do a half ass partial repair, when I know just enough, is not going to last my 90 day warranty, and will only sour the customer, who doesn`t understand, and effects my reputation for quality electronic servicing.

I had a customer years ago(early nineties), whose wife insisted on keeping the non ventilated entertainment hutch doors closed during warm spring days while they worked outside with the house windows open and the stereo cranked up so they could hear it..

I noticed the first time the receiver was brought to me, that it`s circuit boards showed evidence of unusual heat stress for a late eighties receiver, so I questioned him on it`s use, and that`s when he told me about the weekend thermal abuse.
Well I repaired it..
I even suggested taking a box fan and using it to blow into the entertainment hutch with the doors open while they were running it cranked up while they were outside.
Well, he brought back around a year later, with more heat stress evidence, with most of the radial circuit board caps showing signs of swelling !!
So I told him that it looked like he, and or his wife, didn`t take my advice and I wasn`t going to waste my time, and his money trying to reliably repair the receiver again..

Now, all old musical instrument amplifiers, both SS, and tube, brought to me, if not already recapped, will be, or no repair, and that`s final, as my reputation is worth more than making a few bucks !!
Take it or leave it, as I only repair equipment the right/proper way, for maximum performance and reliability..

Do as you see fit, folks..

Kind regards, OKB

 

[rkgren1]

I can only anecdotally contribute to this discussion.
I have recapped several receivers, two for outright faults; popping, banging, hissing, etc.

Two I thought sounded 'muddy' and too strong on the low end, and one (with a reputation as 'powerful') was thin and weak overall.

The ones I repaired are now serviceable. Hurray.
The ones that were working all showed very distinct positive gains in sound quality.
The muddy ones gained noticeable definition in the high frequencies, and the overwhelming low end has been attenuated.
The weak one gained hugely across the board. It was utterly transformed.

I have an exemption to the rule, though.
I have one little receiver, that in A/B comparison (driving the same speakers from the same input through speaker and input switches), sounds as good as anything else that I have.
It has obviously seen no maintenance, but it has lived a charmed life, and I am not touching it.

There is surely no hard,fast rule.
If you like the sound, go with it as-is.
If not, then refurbish to put things back in order.

 

[c.coyle]

Somebody else's gear that you don't want coming back - full recap, replace known troublesome components.

Your personal equipment - up to you.

 

[hemiram]

I'll be changing out the PS caps, if nothing else, as soon as I get the parts I just ordered for two oldish receivers I have. The first is a Panasonic/Technics SA-6500, and the other, which should be here Friday, a Technics SA-500. The 6500 is working and sounds fine, but at 46 years old, I will do it just because I can and will be working on the other one before I ever turn it on. After the big caps are changed out, I wil fire it up and listen with headphones to see if anything is off, and take a good look on the PC boards for caps that show signs of problems. I've gotten good at spotting cooked electrolytics. If you do this regularly, the best thing you can get is something like this:

I got mine, in white, almost new on Ebay for, and I swear it's true, for $14 plus $10 shipping! I was the only bidder on it. Best thing I've ever bought with regards to working on old electronics. So much better than solder suckers, and makes that damn wick look even sadder than it is. Once you get a little time with it, you can yank parts out amazingly fast, without drama. If it cost $200, and it doesn't, it would still be worth getting. Mine is 10 years old now, works as well as a new one. I recapped a board in an old SW receiver a while back in about 20 minutes, vs at least an hour doing it with the solder sucker.

 

[Oerets]

I just recapped a working Marantz 1060 that sounded rather nice. Even did the three big ones mounted to the chassis. They were marked 3000uf and 4600uf, once removed check and they measured 5400uf 5375uf and 6760uf respectively. Don't know if I will check the other caps after hearing the results. Figure there would be a few showing some age. Now the unit sounds more detailed and dare I say more clear. Well worth the few hours and small change to receive the results obtained, IMHO.


Barney

 

[podbaydoors]

As others said, sometimes none of the old capacitors are actually bad, or if they are, they're failing in ways which don't really affect the sound.

For the past few weeks I've been listening to a Realistic Stereo 40A amplifier, from 1961, and all of its capacitors are original.. I re-formed and checked them all, and it sounds just fantastic! I would anticipate a re-cap to be very anticlimactic with this piece.

Usually when I do a re-cap, it's because I encounter one or more failed components, and understand the other similar parts cannot be far behind.

As for hardware that ages and is responsible for deteriorated sound?

-capacitors can get leaky or change in value
-tubes can get weak, go noisy, or develop heater to cathode shorts
-resistors can go noisy or drift, especially carbon composition ones
-plugs and sockets can corrode, and make poor contact or lose spring tensiion
-speakers can deteriorate in terms of weakened suspensions, changed resonant frequencies, dried out glues, etc.
-transistors can develop tin whiskers, or can go noisy
-controls can become noisy or dirty,
-switch contacts can wear out
-belts can stretch, idler wheels can flat spot or go hard
-anything with moving parts can suffer from old lubricants getting sticky or drying out
-old ears can lose high frequency response and sensitivity!

As often as not I have encountered HiFi gear of " a certain age " to still be working, but a bit creaky.
Perhaps the items that suffered catastrophic failure were just tossed in the landfill by original owners who didn't have any sense of preserving an endangered species of electron processors.
I operate under the following presumptions,
(1) Capacitors always get leaky or change in value
(2) Carbon composition resistors will absorb moisture which changes their internal structure and hence will go noisy or drift.
As for the rest, mechanical issues should be expected, lubricant does become glue, although I have encountered more issues with germanium transistors than silicon.
As for the ears, mine worked fine at H.S. graduation in 1974 but now drop off precipitously above 11 KCPS.
But hey, working on the gear is all part of it.

 

[hemiram]

It always seemed like electrolytic caps are so good or bad batch, where some last forever and some die quickly. I've seen and have amps and radios 40+ years old that work fine. I've had a bunch of duplicates of some SW radios that worked fine, others have cap issues, and some are working ok, but it's obvious that cap failure is coming just from the "cooked" look or color change of them. For instance I've had at least a dozen Icom R-71A receivers, and if they are run off 12V, they have few issues, but on 120V, they run so hot it's amazing that at after 30+ years old, that they still work, as the PS runs super hot, enough to kill rectifiers and make solder joints deteriorate. Not to mention it cooks a bunch of caps near to the PS. I had one that someone put a computer fan on the top and cut vents in the PS assembly to let cold air in and hot out. It was a nice job and those caps near the PS looked new. The fan didn't save the rectifier though, it was cooked and the unit did work, but it had a terrible buzz. I bought a PS on ebay and popped it in and ended up selling it at a nice profit. I wish I had kept it. I was thinking about trying to put a bigger capacity rectifier in it but I decided to leave it alone and advised the next owner to run it on 12V.

 

[podbaydoors]

It always seemed like electrolytic caps are so good or bad batch, where some last forever and some die quickly. I've seen and have amps and radios 40+ years old that work fine. I've had a bunch of duplicates of some SW radios that worked fine, others have cap issues, and some are working ok, but it's obvious that cap failure is coming just from the "cooked" look or color change of them. For instance I've had at least a dozen Icom R-71A receivers, and if they are run off 12V, they have few issues, but on 120V, they run so hot it's amazing that at after 30+ years old, that they still work, as the PS runs super hot, enough to kill rectifiers and make solder joints deteriorate. Not to mention it cooks a bunch of caps near to the PS. I had one that someone put a computer fan on the top and cut vents in the PS assembly to let cold air in and hot out. It was a nice job and those caps near the PS looked new. The fan didn't save the rectifier though, it was cooked and the unit did work, but it had a terrible buzz. I bought a PS on ebay and popped it in and ended up selling it at a nice profit. I wish I had kept it. I was thinking about trying to put a bigger capacity rectifier in it but I decided to leave it alone and advised the next owner to run it on 12V.

Yep, usually the cans and anything hit by HV doing rectifier smoothing duty are first to go.
And yet, I have an all original Hallicrafters HQ-129X that still runs excellently, alignment isn't bad at all.

 

[hemiram]

I got my Technics SA-500 today. Dirty isn't the right word to describe it's insides. The insides look black, there is dirt everywhere, but..it works and sounds pretty good! I slid the top off, and I saw nothing obviously bad looking and I cranked it up to about max output and it stayed together with no stink. Switches and controls are all quiet and smooth. I will replace the big filter caps for sure, but don't plan on doing anything else but clean clean clean!

Problems are:

1. Generally dirty, inside real bad, outside just pretty bad. Wood case looks very good!
2. FM seems a little deaf, the tuning cap is noisy on the lower end, still sounds ok when it's tuned in. I hope it's just some of the fuzz inside it that's causing it.
3. Most bulbs are dead.
4. There's a spot of what looks like orange paint near the signal strength meter, under the window/glass. I have no idea what it is and how it got there.

The new and the old. My Yamaha TSR-7810, and the SA-500

Now I need to buy some caps and LEDS

 

[Arthur Smith]

There truly are caps of a certain era, say, from the mid to late 60s on, that make little to no sense to replace. Certainly not to shotgun. I have seen people on YouTube do painfully boring videos showing how they replace every cap in a unit, only to have a problem still exist, or a new one present itself, and not have the troubleshooting skills necessary to do a repair. Recapping is not repair, nor is it restoration. If a unit is maybe from the 40's or 50's, like a tabletop or shortwave radio, yes, recapping makes sense. But it does not solve every problem, and can sometimes, create new ones.

 

[hemiram]

Changing all the caps is not needed most of the time at all. The only critical ones are on the PS and amps, which are worked and heated up 10X as much as the others are. I have seen ham transceivers with most of the caps bad, and it didn't take all that long. My own Kenwood TS-850SAT died four days after I got it used on Ebay. A bunch of the electrolytics had been changed out already, and I did the rest. Even the soldered in lithium battery was leaking. I put in a socket so the battery could be easily replaced. Some of the caps came apart when handled and were basically dust inside. A few had just started to leak, so it was a good thing I went and did it. I noticed in Kenwood ham rigs a habit of using 7v caps on a 5V+ line and cutting it close on voltage ratings in general, and those would fail pretty quickly, replaced by 12V and 15V ones of the same size physically. It still works fine, so I guess I didn't mess up the job.

 

[OMGCat!]

There truly are caps of a certain era, say, from the mid to late 60s on, that make little to no sense to replace. Certainly not to shotgun. I have seen people on YouTube do painfully boring videos showing how they replace every cap in a unit, only to have a problem still exist, or a new one present itself, and not have the troubleshooting skills necessary to do a repair. Recapping is not repair, nor is it restoration. If a unit is maybe from the 40's or 50's, like a tabletop or shortwave radio, yes, recapping makes sense. But it does not solve every problem, and can sometimes, create new ones.

You do have to go on a case by case basis though. I went through a Fisher 500T that had sat for decades in a hot attic in the desert which the owner wanted recapped and the bias checked, etc. Every cap in that thing checked perfectly. Low ESR, no leakage, perfect.
Another one was an early 70's console which is owned by a friend. It was stored in their cool garage for years before she wanting to use it again. It powered on but with very low sound. I pulled a few caps after verifying nothing else was wrong and every single cap checked open. They were all Nichicon and looked fine.

As with most 30+ year old electronics, there are no hard and fast rules.

I work on a lot of 80's gear which doesn't seem to have quite as many caps as 70's stuff. If an owner is shipping something to me I'll recommend doing a full recap (along with everything else that goes along with a restoration) just so we can keep the top cover on for another three decades. If they don't want to or it's local and a return visit won't cost $80 round trip, I'll spot check and replace what's needed. Up to them.
I'm also doing this for beer money and work cheap so the difference between going full boat and not isn't several hundred dollars like a shop. My day job charges $200 an hour so I'm pretty well covered and keep the audio repairs on the fun side.

 

[Karl vd Berg]

A recap in key sections makes difference. There's a HK6100 (from 1991) on bench with a stock input cap of 47uF from Matsushita (blue ones), ESR pretty high. I replaced it with an Elna Silmic of same value, just to see if one cap (per channel) can change the sound. Difference is night and day in SQ.

Not all the PSU caps make huge difference after full recap. The 12,000uF/55V on top (from around 1979-80) were still performing really good in an Aurex amp and were on specs (~11,400uF). They were replaced with new CDE's but these didn't "improve" the sound that much. Other caps in the circuit did it previously, but not the PSU's (which are the last ones in the list to be replaced). Maybe in another unit they could have done it.

Some other caps can make a huge difference in performance, not only replacing with same value, but sometimes changing it to another value (knowing what doing).

 

[steveUK]

Somebody else's gear that you don't want coming back - full recap, replace known troublesome components.

Your personal equipment - up to you.

I think that just about sums it up. It's insurance for service providers, hence they put forward a 'great case' for blanket replacement - and who can argue with an 'experienced tech'?! Otherwise for the individual (many of whom are just as able as the 'experienced tech'), just use your noddle wrt how the unit has spent its life, what are the type/brand etc of caps in there (there are known troublesome ones), if you're still in doubt, pull and try a few for value, leakage and ESR, if they're ok and the set works fine, leave well alone! Sit back, listen and enjoy the set in all it's glorious originality. I have to also say that if people want to perform complete recaps, that's up to them (of course!) but don't try to convince the rest of us that that way is 'right'. After all, the end goal is always enjoyment, and there are many ways to achieve that. We're just pointlessly arguing over two of them. Neither is right, and neither is wrong if it makes you happy and contented. Although I will say - as a final word from me on the subject - one takes a hell of a lot more time and money than the other.