Longevity of organ audio systems

[arie v]

Hi,

I am frequently asked how long organs last, when I service organs. Certainly not a foolish question. I am increasingly seeing organs built in the 70s and 80s that are still being used regularly.

My reason to ask about longevity of amplifiers comes from a question raised by a client, wanting a separate quote on new amplifiers, instead of re-using 30 year old amps, that have never failed. I know the problem with old electrolytic capacitors, but I have seen a lot of amps over 40 years old that have not had any electrolytic caps go bad ( or at the least go totally bad). It has been years since I replaced an electrolytic cap, on either an amp module, or the amp. power supply.

Are there other components that go bad due to ageing?

Can one expect a good, well designed amplifier to last 50 or more years?

I'm not sure that a lot new audio equipment is as well designed and built as older equipment. Of course back then there was no RoHS compliance rules.

I think this RoHS compliant components, circuit boards, lead free solder is going to shorten lifespans of amplifiers and electronics in general.

What do you think?

AV

[KDirk]

I cannot speak to this as an organ tech but I do collect and refurbish vintage hi-fi gear of the mostly 60's to 70's era (late tube era through the solid state hose power wars of the mid to late 70's) and electrolytic caps are a raging argument in that community as well. Some will claim a wholesale replacement is the only proper solution. For longevity that is probably true. I am not so sure about the sound quality being deleteriously affected by older caps though. In some cases there is a clear problem that can be heard and certainly be verified with a scope on the audio signal. Yet, in many cases these amps still sound great to me.

Much of my personal collection of amps has original caps still from the early-mid 1970's era when large filter caps were typically very well spec'd and made as this was the era of monster linear power supplies in mini and early micro computers. Current production is not likely to be made quite as well as no one is expecting 3-4 decades of use from amything now.

Now, I fully expect that a failure to replace these caps at some point will result in catastrophic failure which usually means destroyed output devices at a minium. As many of these old high speed high power TO-3 transistors are getting hard to source that is a concern. Some have no currently available substitutes already and these amps, if blown, will be boat anchors.

ROHS is the kiss of death for modern electronics in this era of surface mount and micro-pitch high density traces and solder pads on printed circuit boards. Lead free solder has already been found to grow near microscopic conductive whiskers over a period of time in applications where traces, vias and device solder pads are very closely spaced. This can do enormous damage depending on the type of circuit and the power levels present therein.

It is also more prone to faults induced by cold joints as the solder itself is not as soft as the old lead alloy types resulting in easier fracturing on boards with a lot of thermal expansion and contraction, or those mounted in such a way that they can sag over time creating mechanical stress. Then too, the modern wave soldering process deposits an absolute minimum of solder on the board so the surface area of solder is reduced and thereby the strength of the resulting joint.

Point of all this being that new gear (pretty much anything post-ROHS) will almost certainly not last as long as previous generations of electronics did.

As far as old amps go, they are generally not difficult to service provided output and driver transistors are available. Large value electrolytics are still surprisingly available but costly. Most new amps are repairable in theory but in practice surface mount makes that very difficult in terms of component level field work. I can't stand reworking SMT boards and I am young enough yet that my vision and dexterity are still good. In 10 years that may not be so true.

Old amps were definitely built better (as a rule, there are always exceptions) than new ones. Newer ones may be more efficient and have more gee-whiz factor but tend to run hotter and closer to design limits as adding leeway in the circuit design costs money they'd rather save in manufacturing. And most outfits are all too happy to have you junk a board or module and pay for a new one - just outside of warranty naturally.

The tradeoff with old hardware is the eventual need for large scale repair or full rebuilding to keep them reliable instead of always having problems to contend with. With labor costs such as they are and the number of genuinely good techs who can troubleshoot and repair at component level so limited it is seldom cost effective to repair versus replace. This keeps the cycle of disposability going though it disgusts guys like me who hate to see good hardware chucked like gabage which so often happens now. Of course, some of the best stuff I own was castoffs from someone too lazy or cheap to do minor repairs so I fixed them myself and pressed them back into service.

I've done this countless times with hi-fi gear, TV's, computers, appliances, cars and even my Rodgers organ. Admittedly not practical for a church or other venue needing a reliable instrument with minimal downtime and lacking a budget to pay a tech for that kind fo work. For an individual as myself, it works out great.

I won't hazard to guess if these older amps (like those used by Rodgers and Allen) will survive in original condition to 50 years but some are not too far from that now and still in regular service.

Kevin

[indianajo]

The 1980 Allen 301 in jeffersonville with Allen S-100 amps suffered silence this fall. new electroltyic caps fixed it. About $35 in parts, including mains caps and the 10 uf power up silence caps. I forgot to order the non-polar caps so I didn't replace those.
Your results may vary, Canada is a lot colder than southern Indiana and the vapor pressure on cracked rubber seals is lower. AndyG in Sussex never seems to need his caps replaced. One of my 1967 hammonds was okay until I put it in an un-airconditioned trailer, then caps started failing. Allens and rodgers have slightly better rubber in their caps, to look at the performance history.
The other thing that can fail in an S100 is any mica washers under the TO3 transistors. Other than that, a little dusting of the heat sink, cleaning of the RCA connector, and go another 30 years, IMHO.
The new consumer grade electronics I buy seem good for about 5 years before they start failing. Your results may vary.

[jbird604]

I can't add a whole lot to what you guys have already said, but I'll kick in some observations. The change to ROHS and surface-mount have both contributed to the decline in life expectancy of new organs in general. We already find that some items built less than 10 years ago are flaking out. We have several Rodgers Masterpiece organs in the area, most of them installed about 2007 and later, and it seems that about half of them are needing a DVM replaced now and then. One of the large surface-mount chips looks to be the problem, as it runs very hot and when we replace one of these boards, we note that this chip looks discolored, as does the solder around it.

Fortunately, amps are less likely to have tiny traces and surface mount components, so maybe they will last longer. We're not seeing many early failures in organ amps built in the past 20 or 30 years. Now and then I have to replace an Allen ADC amp module and haven't had much luck repairing them when they go bad. No SMT in there, so I assume it's something else going bad.

While most older amps, such as Rodgers S-100 and Allen S-100 (odd they both used the same model number), seem to just keep on working, some do fail due to deterioration of electrolytic caps. The Allen amps tend to get noisy or slightly hummy after 30 or 35 years, the Rodgers amps tend to fail catastrophically, either going completely silent (when the output coupling cap opens up) or producing a loud 60 Hz hum that sends the organist running off the bench when the main filter cap opens up.

We've had more than one Rodgers from the 70's go silent when the amps stop working one at a time until the organist finally (!) realizes something is wrong when no stops at all will play (!) ... The cure is to replace all the caps in the S-100's (except some of the very small ones) all at once. I've done this in several cases using readily available standard issue lytics, replacing even those two big ones that stand up through the chassis with ordinary radial lytics. I guess that is cheap and short-sighted of me, but the original type of "computer-grade" caps are VERY expensive in those huge sizes at those voltage ratings. Organs that I repaired this way are still playing fine after 8 or 10 years, so I guess it's going to last as long as the organ does.

But there is IMHO nothing magical about old amplifiers. And new ones are incredible cheap and powerful. Just last year, a big Allen MDS-85 here had to have all 17 channels of amplification replaced, as an electrical fault resulted in the destruction of all the ADC units on the amp rack (fortunately sparing the console). We bought nine two-channel Behringer "iNuke" amps for about $150 each. These amps put out 3 or 4 times the wattage of the original ADC amps, and cost about 1/5 of what Allen wanted for the replacement amps they offered. (The originals were too burned up to even consider fixing.) We had to modify the speaker cables by attaching Speak-On plugs, and the input cables had to be changed to 1/4" plugs. But on the upside, no external muting was required, as the amps do that themselves. And the sound is IMHO somewhat cleaner and more solid than it was with the ADC amps. So, win-win.

Speakers are of course a different issue. We all know that foam-surround cones from the 80's and 90's are dropping like flies. But I have piles of old speakers from the 60's that are still great. I love those big old Allen 15" woofers from the analog organs. I don't know why they can't last nearly forever. Tweeters probably last forever too.

In general, I think there aren't a lot of reasons to try to preserve anything about organs built before 1970. Even a lot of organs pre-1980 probably need to be decommissioned when major troubles appear. This is of course partly because of the availability of so many newer organs for very little money if not free. Like some of the other members of the forum, I tend to think that both Rodgers and Allen did their best work between 1980 and 1999.

[Admin]

Interesting discussion so far. When it comes to electronics, I don't believe in doing preventive maintenance. If it ain't broke, don't fix it especially when replacement parts are non-existent or scarce. While I have some radios going back to the '30's, the oldest electronics I use on a daily basis are in my 1981 vintage Allen MOS 2. When I purchased it in 1998, one of the eight S-100 amps was non-functional due to blown output transistors. Fixed that and they all continue to work to this day. They sound clean with no audible hum so I'm sure their power supplies are fine. I will confess that indianjo's repeated advice to one and all to replace old electrolytics has got me wondering if the amps' frequency response has rolled off it either end of the spectrum, but I've not been motivated enough to pull them out and put them on the bench to measure.

I also have a 25" RCA color tv from 1988 that continues to have a bright and stable picture with it's original electrolytics intact, which leads me to believe that capacitors from that era, at least, were well made and not the weak link they are sometimes made out to be.

I think it's a good guess that today's electronics are not as over-engineered as those of the past and will suffer a reduced life span as a result, but I wonder if it makes any difference. My RCA TV is all but useless except as clunky video monitor for external composite video devices. The tone generation of the Allen has been replaced by Hauptwerk. The rate at which technology advances shortens the useful life of devices regardless of the longevity of their parts.

Of course, the longevity expectations for a church organ are different from that of iPhone, which brings us back to the original question.

[indianajo]

S-100 amps was non-functional due to blown output transistors. Fixed that and they all continue to work to this day. They sound clean with no audible hum so I'm sure their power supplies are fine. I will confess that indianjo's repeated advice to one and all to replace old electrolytics has got me wondering if the amps' frequency response has rolled off it either end of the spectrum, but I've not been motivated enough to pull them out and put them on the bench to measure.
.

The easier test of rail capacitor health is to measure maximum AC voltage into the speaker with a $20 analog meter. A 100 watt amp should put out 28 VAC into a single 8 ohm speaker or 20 into a parallel pair. For a few seconds anyway; consumer grade amps have poorer heat sinks than the organ grade ones so don't do this for minutes on a time on a consumer rated amp. The 1980 S-100 amp at the Jeffersonville Episc. church that had failed in the middle of a service was putting out 2 VAC before I requested authority to buy the new caps. This was with lots of stops, maximum swell and crecendo pedals and the volume knob on the amp turned up.
This test works on tube amps too. My ST70 was putting out 2.6 vac per channel ~5% H.D. when I took it to the MacIntosh amp clinic in 1970. A lot more VAC after cap and rectifier replacement, 17 VAC per spec for 35 watts with also new output tubes. The Harmonic distortion of the tired amp comes from flat top waves - that make sine waves sound like sirens instead of flutes.
Cap service life is variable depending on the seal compound. David A reports there were Green epoxy sealed CDE caps in some guitar amps. Those should last forever. I've never seen one. Sprague made an epoxy sealed cap, I've never seen one of those either. Sprague Atomlytics I bought in 1970 lasted about 5 years. The mallory computer grade caps kdirk refers were very good, with huge water volume to seal area ratio, but were not IMHO forever caps. Neither were the Sangamos in this S-100 amp at the Episc church. You can buy some 10000 hour rated caps now, you can also get 500 hour ones. since about 1970 the e-cap life rating is the choice of the gear manufacturer. Rodgers & allen apparently used pretty good e-caps. Hammond Wurlitzer and dynaco (tube era) , middle of the road service life ones. Hot location lowers service life as vapor pressure is higher. Effective air conditioning of the house helps service life, especially in cool running (well heat sinked or low power demand) transistor amps.

[UncleClark]

I"ll just mention my experience with a Crown power amplifier and preamp, circa 1976. They gave good service until just a couple years ago when first one channel of the preamp lost gain, then the second channel lost gain, and finally the power amp conked out.

It turned out in all three instances the failed component was an integrated circuit (op amp). What I discovered was that the exact op amp used were obsolete and very difficult to obtain, and expensive. The IC for the power amp I could not find at any price. So I threw them away and got new components.

So I would not expect any modern preamp or power amp based on ICs or FPGAs or any other surface mount technology to last 50 years if for no other reason than once something does fail good luck finding replacement parts.

[toomanytoyz]

In more than 30 years in the commercial audio industry I've seen quite a few amplifiers. There are many power amps that have been running 24/7 in paging, life safety, or background music systems for 30 or 40 years or more. I still see tube amplifiers in some applications, I replaced two Stromberg-Carlsons in the past year. I will agree that I see more problems in the new equipment. We have some commercial satellite receivers that are dying from overheating in only 18-24 months. On the other hand, I have older amps that only need a filter or coupling cap replaced to get them up and running again. I regularly replace the can caps in Leslie amplifiers just as a precaution. Recently I went into my bin of used cans and tested some just out of curiosity. Just about every one tested within spec on all sections.