Restoring Vintage Equipment
Jun 8, 2008 at 2:24 AM Thread Starter Post #1 of 20

Tridacnid

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When you restore something vintage, what needs to be replaced? Obviously, safety comes first (discharging caps, double checking specs, etc.). I was thinking capacitors, potentiometers (if any), and tubes. Do resistors degrade over time?

Thanks,
Tri
 
Jun 8, 2008 at 2:56 AM Post #2 of 20

Uncle Erik

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Start with the power supply. Put on a new cord if it has an integral one. If it has an integral cord, you might want to think about modifying it to use an IEC jack. Especially if the original cord isn't ground. Gear wasn't always grounded. So if it isn't, ground it.

Then install a fuse if it doesn't have one. Most gear has a fuse, but still, make sure one is there. Doesn't hurt to pop a new fuse in there, either.

After you make sure it is grounded and fused, replace the electrolytic caps in the power supply. Those take a beating, they're not worth saving and modern ones are a whole lot better. Then look at the rectifier. If it is a tube type, maybe think of a new tube. If it has an old-school solid state rectifier, yank that and put in a modern one. Again, the modern stuff is much better. If you don't have beefy wirewound resistors in the power supply, put those in, too.

A note on the components: get overrated ones whenever possible. If the electrolytics are 47uf 350V, go ahead and drop in 500V or 600V caps if they fit. Won't hurt anything and you'll have an extra margin of safety. Same with resistors. I won't use anything less than 1W, and like to at double the power ratings on parts. If it calls for 1W, I use 2W. 2W gets replaced by a 5W. Doing this typically increases your costs $10-$20 over the OEM values. I think it's worth it, and I've had zero failures in 10 years of restoration work.

The rest depends on how thorough you want to be. Some want to keep the older caps, but I've always been one to replace them all. You don't have to go boutique, Orange Drops sound pretty good and run about $1-$3 each. You can get good larger values at Digikey and Mouser for similar prices. What's an extra $20 to replace them all?

Same with resistors. Yeah, they need to be replaced. The old carbon comp resistors drift like the ocean. Put in some beefy modern ones. I like the Vishay-Dale 1% milspec ones. Prices are reasonable and they sound nice, too.

Pots and tubes hold up pretty well. Pots need to be cleaned with something like ProGold and bad tubes should be replaced. Other than that, they're fine. If you want to upgrade pots to ALPS or stepped attenuators, you can, but the originals can hold up for a long time and still sound good.
 
Jun 8, 2008 at 6:37 PM Post #4 of 20

IceClass

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If you need to replace so much stuff inside the vintage gear and the new stuff is so much better then why bother with vintage kit?
 
Jun 8, 2008 at 7:00 PM Post #5 of 20

nikongod

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Quote:

Originally Posted by IceClass /img/forum/go_quote.gif
If you need to replace so much stuff inside the vintage gear and the new stuff is so much better then why bother with vintage kit?


to get the SQ of a good vintage bit of gear from a new production piece you need to spend some SERIOUS money. agreed there is some worthless junk, but not as much as there is today.

if you like the thermionic valves, you can spend as much on a pair of new transformers as the whole vintage amp with better transformers that just needs a once over.

fortunately for the DIY'er most of the vintage gear was designed to have parts easily swapped with terminal strips and stuff. very easy.

As a last note: before 1940, many of the "great minds" of the USA electronics industry were in the audio world because there was at least the same ammount of money here (in audio) VS in the military. After 1945 the great minds were all in the military....

If you like transistors, you should not look at vintage gear. not anything older than about 1980 or so. your opinion of the transistor will not be improved if you look at the "perfect" amps of the 1970's.
 
Jun 8, 2008 at 10:52 PM Post #7 of 20

IceClass

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Quote:

Originally Posted by nikongod /img/forum/go_quote.gif
If you like transistors, you should not look at vintage gear. not anything older than about 1980 or so. your opinion of the transistor will not be improved if you look at the "perfect" amps of the 1970's.


Uh-oh! Almost all my non headphone amplifiers are late 70s to early 80s production like Toshiba M15s, Nakamichi 620 & 420, Cyrus 2, NAD 3240PE and a cute as pie little AIWA A22 that I just snagged without a plug and haven't heard yet. I'm coveting a Bryston 2B and have been seeking a Mitsubishi MA01 for ages.

I wouldn't have a clue where to start or how to mod any of them in any way and dunno if it would even be economical.
 
Jun 9, 2008 at 1:18 AM Post #8 of 20

Uncle Erik

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Quote:

Originally Posted by IceClass /img/forum/go_quote.gif
If you need to replace so much stuff inside the vintage gear and the new stuff is so much better then why bother with vintage kit?


Ah, you get to reuse the iron and casing. If you undertake a DIY project, you'll quickly realize that the transformers and case take up a huge amount of your budget and time. Soldering in the various bits is an evening or two. Getting the case right can take a week or two of evenings and weekends. And if you want good iron, you pay for it. The good news is that the old cases and transformers often hold up well, like 60 or 70 years well, and even longer if cared for.

As Nikongod pointed out, there were a lot of sharp minds in audio back then who designed wonderful circuits.

Unfortunately, they only had wax and paper capacitors and carbon comp resistors to work with. Those don't hold up in the long term, but the new stuff is much better.

So, you get a nice case, good transformers, genius in the circuit, and an evening or two replacing the old, unreliable bits. If you don't go wholly boutique, you can recap and swap out the resistors for $50-$100. And with modern components, you'll be passing the gear along to your grandchildren.

Same with the old radios - they're wonderful cleaned up with new components.
 
Jun 10, 2008 at 3:59 AM Post #10 of 20

Uncle Erik

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Quote:

Originally Posted by Tridacnid /img/forum/go_quote.gif
Another question. Uncle E, what brand of electrolytics do you like to use?


All sorts of them, I'm not picky. Got some Blackgates for an upcoming project, but I've used a lot of Nichicon, NTE, and others.

But more than particular brands, I like 105 degree C rated caps, tight tolerances (5% or better if available) and shoot for at least 100V over the rating in the circuit. That usually gets stuff to run cool and gives you an extra measure of protection against a failure that cooks off some tubes.
 
Jun 10, 2008 at 4:18 AM Post #11 of 20

Telynau

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Any restoration of tube gear needs to be undertaken very carefully if you don't have prior experience. In power amplifiers especially, voltages are present that can knock you out of your chair or worse. There is a reason some old timers would only test live equipment with their left hand in their pocket. If you don't know what that reason is, find someone to help you do the work or do it for you.

Regards, James
 
Jun 10, 2008 at 5:04 AM Post #12 of 20

Sovkiller

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I will not bother with vintage at all, you will end spending as much as a new amp, at the end, and you will have an old amp anyway, that could fail of anything else that was not replaced, even the wires.....just begin to pop BG caps or more expensive, and so and so, and you will end with a pretty high bill...unless you have them in stock of course...
wink.gif

Also you can get nowadays, choosing wisely and in the used market, for 300-500 very good amps, that will beat the dust of any vintage. I used to own, old Pioneers, Technics, Onkyo, Trio, Sansui, Kenwood, etc...amps from the golden era of the 70-80 in solid state, mainly because I love the sturdy construction, look, and sound, and I still do, but honestly my Marantz PM7200 sounds ages better than any of those I had, and mainly all of the them were class AB, not even Class A, not that this matters too much if the amp was well implemented, but another point down...

Now with the new generations of digital amps out there, the vintage will have a very rough time...Always look forward, not back, leave the past to the grandpas....
wink.gif
 
Jun 10, 2008 at 5:59 AM Post #13 of 20

nikongod

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Quote:

Originally Posted by Sovkiller /img/forum/go_quote.gif
I will not bother with vintage at all, you will end spending as much as a new amp, at the end, and you will have an old amp anyway, that could fail of anything else that was not replaced, even the wires.....just begin to pop BG caps or more expensive, and so and so, and you will end with a pretty high bill...unless you have them in stock of course...
wink.gif

Also you can get nowadays, choosing wisely and in the used market, for 300-500 very good amps, that will beat the dust of any vintage. I used to own, old Pioneers, Technics, Onkyo, Trio, Sansui, Kenwood, etc...amps from the golden era of the 70-80 in solid state, mainly because I love the sturdy construction, look, and sound, and I still do, but honestly my Marantz PM7200 sounds ages better than any of those I had, and mainly all of the them were class AB, not even Class A, not that this matters too much if the amp was well implemented, but another point down...

Now with the new generations of digital amps out there, the vintage will have a very rough time...Always look forward, not back, leave the past to the grandpas....
wink.gif



The questions of what an amp of yesteryear will compare to today should be noted with the statement that you are strongly biased against tubes regardless of what they do, how they measure, or anything to their benefit over a solid stage amp. regardless of why you form this opinion, as i see things this is what it is.

why do you imply that you *need* black-gate caps? standard computer grade low-esr types work amazingly well for many tube circuits, and are likely far superior to the original equipment which already sounded good. a good circuit will usually sound good with average parts. circuits that only sound good with botique parts are a joke.

have you ever seen a piece of wire fail? There are dangers in refurbishing old gear, but that is just a contrived example. you could of course replace all the wire in the amp when you redo everything else if that bothers you.

the 70's and early 80's were the worst time EVER for solid state amps, although the trend towards "switch mode everything" (class-D) is going to challenge my statement there. The majority of the old transistor amps sell for pennies over scrap value, sometimes less. i would add that buying a vintage transistor amp IS a timebomb. once you replace the parts in the PSU, and elsewhere as necessary you are only waiting to blow a transistor (which may not happen, but this is a response to slightly far-fetched comment anyways) which WILL render the amp worthless because you cant get old transistors.
 
Jun 10, 2008 at 6:41 AM Post #14 of 20

Spasticteapot

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Quote:

Originally Posted by nikongod /img/forum/go_quote.gif

If you like transistors, you should not look at vintage gear. not anything older than about 1980 or so. your opinion of the transistor will not be improved if you look at the "perfect" amps of the 1970's.



I would agree that with few exceptions, the amps of the 1970s do not compare with modern gear.

However, I can - and have - purchased a Sansui 7900Z receiver for all of $35. It has a decent tuner and phono preamp. It's also capable of over 100 watts per channel without sweating.

Compared to what you'll find for under $150 from Pioneer, Sony, and Onkyo, it's a pretty good bargain indeed.

On the other hand, the early 80s was full of BPC - Black Plastic Crap. The falling price of semiconductors meant that stereo equipment could be built cheaply, and as a result, it was: horrible STK amplifiers-on-chips replaced discrete output transistors, power transformers shrunk, and designs focused not on distortion but price.


Quote:

Originally Posted by Sovkiller /img/forum/go_quote.gif
I I used to own, old Pioneers, Technics, Onkyo, Trio, Sansui, Kenwood, etc...amps from the golden era of the 70-80 in solid state, mainly because I love the sturdy construction, look, and sound, and I still do, but honestly my Marantz PM7200 sounds ages better than any of those I had, and mainly all of the them were class AB, not even Class A, not that this matters too much if the amp was well implemented, but another point down...
wink.gif



Class A is an incredibly expensive and inefficient layout for an amplifier - there's a reason why you only see it on ultra-high-end gear. Your Marantz PM7200 may be excellent, but it cost $500 - and only produces 25w, not leaving much headroom for inefficient speakers.
 
Jun 10, 2008 at 6:59 AM Post #15 of 20

Uncle Erik

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Quote:

Originally Posted by Sovkiller /img/forum/go_quote.gif
I will not bother with vintage at all, you will end spending as much as a new amp, at the end, and you will have an old amp anyway, that could fail of anything else that was not replaced, even the wires.....just begin to pop BG caps or more expensive, and so and so, and you will end with a pretty high bill...unless you have them in stock of course...
wink.gif



Sov, the expensive parts of an amp are the case and transformers. For example, I just got the iron for Ciuffoli's SESS amp. Granted the exchange rate is terrible, but the iron is running about $700. Snotty boutique caps and resistors were maybe $100. If I used high quality non-boutique parts (which probably wouldn't change the sound that much), I could have scrounged them for under $25. The casing is going to be some aluminum plates I'm massaging... probably another $100 there.

With vintage, you can almost always reuse the case and iron. It's easy to see if a case is in good shape before you buy and your nose will usually sniff out a fried tranny without even opening the case. You don't need a day at the bench to see if a Hamfest find is worth reworking.

Take something like an old McIntosh tube amp. Those usually have the components on a strip board inside - easy. Get that out and you can replace everything in 2-3 hours. If you don't go boutique, you can do it for $50-$60 with pretty good stuff.

If a wire looks bad, just replace it. Takes a few minutes and you can use nice Teflon wire that'll work out to $1 per foot. If you're willing to spend 7-8 hours on the amp, you can replace everything. Not that hard - I did that to an old Stromberg Carlson AM/SW set recently and it came out great.

Also, I use overrated components for everything. The margin of safety is generally better than in new amps.

Yes, this stuff is expensive if you pay someone to do it, but if you have room for a small bench, you can do it over a few evenings and end up with wonderful gear on the cheap.
 

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