Is there really an audible difference before and after recap/restoration?

[gbroot]

It doesn't hurt that the OP was listening to one of the better if not best sounding vintage receivers of all time. The Pioneer x3x series was far enough in the Solid state chain that significant improvements had been made over tubes, yet not so far along that cost cutting impacted fidelity. IMHO x5x and x8x series Pioneers just don't hold a candle to the x3x series, each one a step downward in sound quality.

Lot's of good comments that make a lot of sense. As far as x3x Pioneer series vs x5x and x8x, I am in total agreement. Interestingly the 939's larger brother, the 1010 gets all the attention and the big bucks while the 939 remains under the radar but basically shares many of the same boards and components as the 1010 and is only slightly less powerful. The 939's Marantz counterparts are the 2270 and 2275 and look what they bring in restored condition. I've been chillin with the 939 and my KLH 23's along with some smooth Larry Carlton this evening. Life is good.

 

[wmgwizard]

What is the point in re-capping a properly functioning amp? If I was going to tweak an amp, I would focus on everything else and include the caps incidentally. In other words, an actual re-build. That's how you will realize an improvement, if any. Just setting bias/offset will make a huge difference over just changing caps in good condition. A 25 year old amp needs re-building no matter how good you think it sounds, caps and all.

Typically the caps are the only components that actually deteriorate, changing resistors and transistors is usually a waste of time and money in most cases. There are instances where some transistors have demonstrated they are prone to failure and it makes sense to change them out but rarely does such a change impact sound quality as much as new caps.

 

[jeromach]

What is the point in re-capping a properly functioning amp? If I was going to tweak an amp, I would focus on everything else and include the caps incidentally. In other words, an actual re-build. That's how you will realize an improvement, if any. Just setting bias/offset will make a huge difference over just changing caps in good condition. A 25 year old amp needs re-building no matter how good you think it sounds, caps and all.

I agree here. Fine tuning the amp can make a significant difference. Of course all vintage gear has been used for quite a while, so dc offset and bias may have run off from specs, but I sometimes have the impression certain manufacturers didn't care to adjust it correctly even before leaving the factory.

As for total re-builds; it's the way I have experienced the most significant improvement in sound quality. Still, I once almost got in an e-mail fight with an old school tech who "informed" me how ridiculous it was I replaced transistors with "equivalents". There ARE no equivalents was the message, the original transistors were far more superior (in the particular circuit) than any modern day replacement transistor could ever be. Doubting the choices of the original engineers was a profanity from my side.

Well, could be, but in the end what I trust most are my ears (and those of the ones I do these rebuilds for).

 

[Superampman]

Typically the caps are the only components that actually deteriorate, changing resistors and transistors is usually a waste of time and money in most cases. There are instances where some transistors have demonstrated they are prone to failure and it makes sense to change them out but rarely does such a change impact sound quality as much as new caps.

May I ask where you gained this knowledge?

 

[wmgwizard]

Twenty five years as an enthusiast/amateur tech and a few years hanging around here.

Electrolytic capacitors are constructed of foil and paper, over time the paper deteriorates and the value of the capacitor changes.

Resistors may change value over time but rarely to the extent that they will be so far out of tolerance that they affect the circuit. Resistors that encounter thermal stress(like biasing resistors) are more likely to be replaced during a re cap/restoration, more as a preventive measure than operational improvement.

Transistors generally either work or they don't. There are no moving parts or materials used in their construction that deteriorate over time. Just like resistors, transistors that experience thermal extremes should be considered for replacement during a rebuild. This is a risky proposition as there are very few exact replacements and changing various parameters with "equivalents" may indeed affect the sound, proceed with caution.

 

[ConradH]

It's the old "rule of thumb" problem. I've seen everything go bad at one point or another. Other times, 40 year old equipment is near perfect. Transistors don't go bad, unless they do. And they sometimes do. Look at the '458 "low noise" jobs that get so noisy over time. The only real answer is to get the equipment on the test bench and determine what the real situation is, and then get everything back up to spec. FWIW, I don't think I've ever put anything on the bench and found absolutely nothing wrong. By the time you can hear it, things have degraded pretty far.

 

[Skylab]

I have two Pioneer SX-1980s that were completely recapped as well as having other required restorations done (all 1980s need the power supply board rebuilt, etc.). The difference between the before and after sonically was definitely noticeable and very significantly for the better. I have no way of knowing just how many out of spec caps there were, or how badly they were out of spec, but the performance after restoration was much better than it was prior to it.

Of course in addition to that, the restored units have already provided several years of reliable, trouble free daily service, and should continue to for quite a while.

 

[bare]

Twenty five years as an enthusiast/amateur tech and a few years hanging around here.

Electrolytic capacitors are constructed of foil and paper, over time the paper deteriorates and the value of the capacitor changes.

Resistors may change value over time but rarely to the extent that they will be so far out of tolerance that they affect the circuit. Resistors that encounter thermal stress(like biasing resistors) are more likely to be replaced during a re cap/restoration, more as a preventive measure than operational improvement.

Transistors generally either work or they don't. There are no moving parts or materials used in their construction that deteriorate over time. Just like resistors, transistors that experience thermal extremes should be considered for replacement during a rebuild. This is a risky proposition as there are very few exact replacements and changing various parameters with "equivalents" may indeed affect the sound, proceed with caution.

Hmmmm ..40 years on since my first DIY amp and of being a 'mostly' constant Audio Weenie/dilletante.
Likely ingested a dangerous dose of solder fumes by now..
However I can claim no such knowledge.
I'm clearly a Sloow learner, I suppose

 

[Superampman]

Well I have not built an amp but I certainly ingested enough solder fumes over the last 35 years to build one. I think it's ignorant to assume the only likely benefits an old amp can acquire are new caps. I wonder how many with just new caps fall into spec. I would venture to guess maybe...none! A good test for overall functionality is to check for offset at the output. Even if they do fall into the outer tolerances, they are not going to sound as good as new (or better in a lot of cases due to current technology parts). There's a big difference in sq going from 2mv of offset to 30-50. I guarantee I can tell the difference when comparing two identical make/model. Both will be technically acceptable. Both will have properly functioning diff. pairs. But the high offset one's won't be balanced to each other anymore. And good luck getting a 30yr. old single turn trim pot to be stable. Any resistor close to heat will potentially drift. Diodes can crack and leak. Output transistors can weaken. Solder joints can give way. I have run into every one of these issues. Mind you I have a lot of gear but it's never been sufficient to just change caps. Interestingly, I have not yet had to replace a bias resistor.

 

[wmgwizard]

Please don't twist my words.

I never said that re capping a unit would make as good as new, but that is not what this thread is about.

I did indicate there were other components to consider replacing. I also issued a caution that very few transistors have exact replacements, unlike capacitors and resistors, and that differences in some parameters may have an impact on sound quality.

I do stand behind my assertion that needlessly replacing components is a waste of time and money.

I never claimed to know it all so please tell me how a diode leaks?

How do you measure an output transistor to see if it has become weak?

Glad to hear you have never replaced a biasing resistor, I merely suggested it was done as a preventative measure, along with any others exposed to thermal stress.

Weak solder joints should be discovered during the initial assessment, yes they are all too common but not relative to this discussion.

In those instances("leaky" diode, "weak" transistor) you have a unit that is functioning poorly, if at all. That is not the topic of this discussion.

If you have never dissected a capacitor to see whats inside, perhaps you are a weenie.

Make sure you thoroughly read and comprehend the posts and responses before commenting.

 

[Hyperion]

The definition of "re-capping" might be different depending on who you ask... :yes:

I have seen some so called "re-capping" (clearly taken very literally by the perpetrator) and have been disgusted with what I consider to be poor workmanship.

Restoration and reconditioning - should encompass changing all electrolytic capacitors, and a host of other tasks to ensure the equipment set-up (i.e. Bias and DC offset) stays where it is put and thus the equipment/Amplifier performs reliably.

 

[Superampman]

Please don't twist my words.

I never said that re capping a unit would make as good as new, but that is not what this thread is about.

I did indicate there were other components to consider replacing. I also issued a caution that very few transistors have exact replacements, unlike capacitors and resistors, and that differences in some parameters may have an impact on sound quality.

I do stand behind my assertion that needlessly replacing components is a waste of time and money.

I never claimed to know it all so please tell me how a diode leaks?

How do you measure an output transistor to see if it has become weak?

Glad to hear you have never replaced a biasing resistor, I merely suggested it was done as a preventative measure, along with any others exposed to thermal stress.

Weak solder joints should be discovered during the initial assessment, yes they are all too common but not relative to this discussion.

In those instances("leaky" diode, "weak" transistor) you have a unit that is functioning poorly, if at all. That is not the topic of this discussion.

If you have never dissected a capacitor to see whats inside, perhaps you are a weenie.

Make sure you thoroughly read and comprehend the posts and responses before commenting.

This is what you responded to my post:
"Typically the caps are the only components that actually deteriorate, changing resistors and transistors is usually a waste of time and money in most cases".


I take it you've changed your mind and are now in total agreement with me.
In any case, you've assigned your own context to my subsequent statements. Looks like you are correct. So where's the bliss? Answers to your questions can be found in AK's archives I'm sure, or Google is your friend.

Btw, weenie? Seriously? Is that some kind of team-player thingy?

 

[wmgwizard]

I have not changed my mind and I don't agree with you that randomly shotgunning a project with parts is the way to proceed. Replacing parts that are not typically prone to failure and are currently within spec is a waste of time and money. You don't change a lightbulb just because.

I did not ask the archives or Google to support your position, I asked you.

There is a distinct difference between a restoration and a resto-mod. A restoration seeks to use as many of the original parts to preserve the historic integrity, a resto-mod replaces everything with modern equivalents and produces a completely different result.

 

[Superampman]

I have not changed my mind and I don't agree with you that randomly shotgunning a project with parts is the way to proceed. Replacing parts that are not typically prone to failure and are currently within spec is a waste of time and money. You don't change a lightbulb just because.

I did not ask the archives or Google to support your position, I asked you.

There is a distinct difference between a restoration and a resto-mod. A restoration seeks to use as many of the original parts to preserve the historic integrity, a resto-mod replaces everything with modern equivalents and produces a completely different result.

I didn't suggest randomly doing anything. What I made clear is that typically, a 30 yr. old amp will need much more than caps and that imo, they are incidental to the real task at hand. Replacing parts with modern equivalents is not a mod, but in many cases still better in that tolerances may be tighter rendering a more accurate and reliable outcome. This can in many cases result in a better than new performing amp. Not different, but with less THD.

As far as taking me to task is concerned, It seems it would be up to you to prove otherwise, no? In the mean time, grab a popsicle and chill out.

 

[blackfly]

I have 2 Luxman M 05s in my system. One had a total recap done 6 months ago, and the other is a gently used unit that is original in every way.

I was expecting there to be a difference in the recap (I did spend $1000 and used only Nichicon caps, decent ones) and the difference between the two is ziltch. Nada. I cannot tell them apart. But the recapped one has new caps that are not going to fail anytime soon. The other unit...... well, it might have a cap go bad sometime, certainly sooner than the other one.

But sonically, the only reason other than caps going bad and NEEDING changing, to expect it to be better is to me, at least with the gear I have, insignificant. I was a bit disappointed, in that after spending the money I would of expected something; ANYTHING, but in reality got nothing. Nothing except peace of mind.

 

[jheu02]

$1000 for one amp! I don't know how many caps that might have been, nor whether other work was done too, but that sounds like highway robbery to me.

EDIT: One thing to think about in recapping: if you've never heard the unit that's being recapped when new, you've never really heard what it was supposed to sound like, IMO. And even if you did hear it brand new, our memories have a way of remembering the good parts, and maybe not the bad...nostalgia if you will. So, recapping to me is mainly about service life/preventative maintenance. But I also regrease the outputs and others, re-bias, check offset, and do further things like relay replacement if the original is acting up, etc. On units where others much more knowledgeable than me have stated there's certain transistors or other parts that typically go bad, I'll usually replace those also with the recommended substitute. They've already done the research while fixing broken parts, so I use that as my gauge for what to do (in addition to the caps).

 

[Sam Cogley]

Typically the caps are the only components that actually deteriorate, changing resistors and transistors is usually a waste of time and money in most cases. There are instances where some transistors have demonstrated they are prone to failure and it makes sense to change them out but rarely does such a change impact sound quality as much as new caps.

Some transistors are notorious for deteriorating and causing all sorts of crazy issues, from white noise to complete random dysfunction.

Electrolytic caps have a semi-liquid electrolytic paste in them. Whether used or not, that dries up over time, at which point they are not functioning as they should, even if they are functioning.

Carbon comp resistors are notorious for deterioration.

Another post included a question for testing transistors to see if they are weak. One would do that with any number of different transistor testers.


I recently finished a long-running project: the rebuild of two badly abused and neglected Fisher 70 series tube amps. When I was finished, the only original parts left were three of the four transformers (one PT was shorted, and was replaced with a part from a trashed 80 series amp), the two chassis, some of the internal wiring, and eight of the ten tube sockets. Everything else was so questionable or corroded that it was easier to simply do a complete replacement than track down which resistors, pots or switches were causing problems.

 

[jeromach]

I am on the brink of finishing a Sansui AU-666 rebuild.

But I have an issue, two of the outputs have a significant difference in gain, like this;

2SD188 11
2SD188 10
2SA627 27
2SA627 113

What should I do?

 

[Trekmaster]

My Rebuild story!

So I purchased my 70's dream receiver a Pioneer SX-950 that all my friends had back in the 70's. I only had it for a week before I realized that it was acting twitchy and the tone circuit was acting up. So I only heard it for a short time as it was replacing my regular pioneer surround receiver.

So 6 months later and back from a restore from Pacific Stereo, she was just beautiful out of the box like brand new. Sounded great and my music never sounded better. However after 2 weeks of daily listening all of a sudden she is producing bass like I haven't heard in years! The rest of the spectrum is well balanced.

But when I listened to ghost in the machine by the police last night it was like the bass player was in the room live. I've seen stories from both sides on burn in and can appreciate both sides opinions. But here is mine for what it's worth. The sound coming out of my JBL 4312'S now is much better from when I got it back it's smoother and deeper in tone.

I'm a very very happy camper and my 70's listening space is almost complete! Just picked up a lava lamp now I'm working on a 3 color light box! No I'm not 29 but 59 and I'm currently living in the past and enjoying every minute of it!

 

[loopstick]

I recapped my Olson and the hum went away. Probably could have stopped at the power supply but did all the electrolytics down to 3.3 uF. It was fun. Kinda nostalgic. Did the improvement inspire me to recap anything else in the stable? Nope. They don't hum.

I know that begs the OP question. You kinda have to imagine a potential improvement then decide if you want to try to achieve that imagined potential. In these cap threads I'd like to see some specific testimony about which specific caps (DC filtering, AC coupling, etc) made which specific audible improvements. Then your efforts could be directed towards specific improvements and you'd be able to verify if such improvements were actually achieved.

edit: This would serve to de-mystify the capacitor and put some informed focus on the particular function of each cap being replaced. It could even encourage a placebo effect even if the cap made no change at all to the sound. I have to admit in my mind the Olson sounded nice and bassy. But I had no real history of listening to it because when I brought it home from GW it buzzed awful and I shut it off.