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Are there Negatives to a Rebuild

Willie B.

Willie B.

New Member
This topic has probably been covered, but I couldn’t find the answer I am looking for (perhaps looking for the wrong answer).

There are a lot of nice pieces out there. Is there any damage done to sound by a top to bottom rebuild?

This is specifically for solid state.

With a job of Nichion, Elna, Wima, etc, do you change a receiver to sound like every other receiver that has seen the same work?

If this is even kind of true, where is the tipping point?

I have been in need of a new unit and was able to pick on up (thank you AK). It is going to see the full rebuild because I can, and I don’t want to worry about it 6 months later if I can’t.

I know it will sound good, but I have had a long string of equipment holding on by a thread. They all had their own sound.
 
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This topic is debated every time it is raised.

My belief is that the sound of an amplifier is defined predominantly by its design. I think the risk of changing its original performance/SQ characteristics with new, high-quality parts having the same pertinent specs is very, very low.

I would also say that if the unit is more than 25-30 years old, it is highly likely that it does not sound/perform like it did when new, primarily as a function of deteriorating capacitors, but also drifting specs of semiconductors and even resistors, noisy switches, pots and relays, etc.
 
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Having QRX Restore, restore my Sansui AU-7700 did not change the sound and I have an unrestored QRX-6500 to compare it to.
I have A/B'd them driving the same speakers with a selection box.
 
To the extent the unit has declined in performance due to degradation of components (a given as regards electrolytic capcitors), a rebuild will restore it to original performance...or at least much closer.

Added via subsequent edit:

And it will reduce the chances of chain reaction failures that may take out components that may be difficult or impossible to replace...for example, the outputs in my Sansui AU919. Finding even mundane through-hole replacement components is rapidly becoming a problem, as many such parts are being obsoleted by the manufacturers.

Restoration/rebuild is the best way to assure that a favorite "vintage" amp or receiver is around for another decade or three...and brings it back to its original performance (or certainly closer to it) to boot.
 
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There's a big difference between 'ain't broke' & 40 years old, and fully and correctly reconditioned by someone who knows what he/she is doing.

Many fall back on 'ain't broke' when in the case of a Sansui, the corrosive glue is quietly munching its way through many component leads. Eventually to present you with a non-working amplifier, requiring substantial rework and replacement of potentially 'unobtanium' parts - which wouldn't have been damaged if attended to sooner. Yeah - 'ain't broke' until it fails catastrophically. :(
 
The major risk (IMO) is doing it wrong. Board damage from desoldering, installing the wrong value part, that kind of thing. Personally speaking I haven't been upset at the results any time I actually went through the whole process of overhauling something. I usually just put it off because its kind of annoying to actually go build the order list. I do prefer to start from a working unit though, re-capping stuff that doesn't work properly is very much a gamble if you don't at least have a pretty solid reason for thinking the malfunction is in fact capacitor related. Stuffing a bunch of new parts in something that doesn't work may end up with something that still doesn't work, plus a pile of new variables to rule out.

I've also dealt with rotted boards from capacitor leakage in the past, and I can tell you its not the most fun thing in the world. Far less likely to see this in things in a climate controlled environment but a garage / barn / attic find that sat for many years in alternating baking and freezing temps can have significant problems. Automotive electronics are an absolute disaster about this stuff.
 
Hyperion said:
There's a big difference between 'ain't broke' & 40 years old, and fully and correctly reconditioned by someone who knows what he/she is doing.

Many fall back on 'ain't broke' when in the case of a Sansui, the corrosive glue is quietly munching its way through many component leads. Eventually to present you with a non-working amplifier, requiring substantial rework and replacement of potentially 'unobtanium' parts - which wouldn't have been damaged if attended to sooner. Yeah - 'ain't broke' until it fails catastrophically. :(
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Thanks for the best explanation that I have read.
My Sansui AU-7700 was a factory DEMO, which did not have the infamous glue.
 
gadget73 said:
The major risk (IMO) is doing it wrong. Board damage from desoldering, installing the wrong value part, that kind of thing. Personally speaking I haven't been upset at the results any time I actually went through the whole process of overhauling something. I usually just put it off because its kind of annoying to actually go build the order list. I do prefer to start from a working unit though, re-capping stuff that doesn't work properly is very much a gamble if you don't at least have a pretty solid reason for thinking the malfunction is in fact capacitor related. Stuffing a bunch of new parts in something that doesn't work may end up with something that still doesn't work, plus a pile of new variables to rule out.

I've also dealt with rotted boards from capacitor leakage in the past, and I can tell you its not the most fun thing in the world. Far less likely to see this in things in a climate controlled environment but a garage / barn / attic find that sat for many years in alternating baking and freezing temps can have significant problems. Automotive electronics are an absolute disaster about this stuff.
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Excellent points about the risks of damage from doing low quality work, and the importance of trouble diagnosis/resolution prior to rebuilding/restoring.
 
Equipment may sound closer to more "modern" units after a rebuild- tighter, clearer, colder, more detailed, and with greater "energy/ impact" (with the high ripple caps everyone is using) and better speed, musical separation, and quieter noise floor, especially depending on what materials are used and in what sections. Going into a rebuild, 40-50 year old equipment may have that "vintage" sound we like and want to preserve. At the same time, this isn't always necessarily how they sounded when they were new either and need to be refreshed. Some of the vintage sound- "tubey, warm, fat, organic, etc" has to do with out-of-spec components, while some has to do with circuit design.

When I see something that has been freshly rebuilt as a selling point it turns me off. I immediately question what parts were used and quality of the work because it will have an impact on the final outcome. I'd much rather do the rebuilding myself than assume anyone else made the right/ best choices- especially as it relates to component selection, matching (stereo) pairs, replacing green illumination lights with blue LEDs, etc.

Anyone taking a one-and-done, parts is parts approach may be holding back the design potential. Manufacturers often did not even take the designs to their fullest to keep costs down by using cheap passives implemented on otherwise very good sounding circuits.

A rebuild is not something to be rushed. I see it as more of an art, sometimes requiring 2-3 rebuild versions where a few parts are swapped in/ out, here and there to arrive at the best sound from the parts I have available- depending how it initially sounds afterwards. If I'm blown away by the sound or can't imagine how anything could be improved further, then it stays that way. Also, good equipment has to earn its restoration. If it doesn't sound somewhat special to begin with, then I won't even bother with it.
 
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The idea that the sound would return to original spec only holds true if you install original spec parts.

Good luck with that.

Modern "equivalents" will produce moderately equivalent results. There will be some difference. The problem is we don't have a fresh off the assembly line unit to A/B with so we will never truly know if it sounds the same, better, different ?????

It's only original once.
 
wmgwizard said:
The idea that the sound would return to original spec only holds true if you install original spec parts.

Good luck with that.

Modern "equivalents" will produce moderately equivalent results. There will be some difference. The problem is we don't have a fresh off the assembly line unit to A/B with so we will never truly know if it sounds the same, better, different ?????

It's only original once.
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It will be a hell of a lot closer than a unit with 40 year old electrolytics, noisy signal caps and carbon comp resistors. Properly spec'ed components will yield a unit as close to original as you can get.
 
Original design was done with available parts in the day. The 60s and 70s were the Stone Age compared to modern times, especially in manufacturing.

We live in the future. We got computers and lasers and robotics and internet and all kinds of cool stuff now.

Any serious dig into e-cap tech and the companies own paperwork (internet, remember?) will show that e-caps are not going to last forever.

No one drives a 40-50 year old car with original parts. Do you even remember bias ply tires. ‘Manual steering, manual drum brakes, points and condenser ignition, naturally aspirated fuel system (carburetor). Jesus! I got a 70 Chevy pickup with that and keep it for nostalgia and fun but gawd damn, I ain’t daily driving it and never going on a road trip again with it. No AC and the heater is almost good enough.

The sound is in the design.
It damn well better sound better after a good rebuild. Clearer highs, deeper lows. If you can’t tell, check your ears and speakers.

There is a list of transistors that haven’t aged well, they get noisy. I find them all the time.

I find bad e-caps more and more these days in vintage.

There is no intelligent reason against a proper restore.

But, big but, if you like the sloppy sound now and.or your ears are shot and or your speakers are lame, then don’t bother.

And If you do restore, do a proper job of it. Don’t go hacking away on nice gear.
 
roger2 said:
I wonder how many times this topic has been debated :dunno:
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And how many times more it will be.

To be clear, I'm a believer in preventive maintenance. If I have an item of equipment that is older I will be replacing items that will be likely to fail and cause damage to other, harder/more expensive to repair/replace before they cause an issue. Capacitors and in some cases relays for example. To me it's common sense. To others it's "ruining the mojo".
 
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