I'm looking to buy a Studer A80 and would like some advice.
First, I commend your selection of the A80. You've chosen what many feel is the best tape machine ever designed.
In what follows, I've freely pasted-in selected snips from you and from some of the other responses to your post. These are preceded by the >
To anyone who actually understands (or can hear) the critically important contribution of the tape transport to the sound quality of an analog tape machine, the servo constant tension, precision guidance A80 is probably twenty times more desirable than an A807 or A810. (Some experts don't regard these low-cost, mass-produced machines designed for the radio station market as being real Studers.)
Bottom line is that A80s are still out there and they are definitely almost always worth acquiring. ATAE presently has thirty in our warehouse in California, awaiting re-manufacturing.
Having addressed that topic, can you please now state the reason for your purchase of a Studer A80? Are you firmly set on buying a recorder - reproducer? If so, what exactly are you planning to record? It's very common in the audiophile community to see tape recorders employed almost exclusively for playback. However, this makes very little sense, as for highest sound quality, you'll instead want a reproducer. NOT a recorder!
> RC is the one to go with or the R? I've heard the R is best sound quality
The folklore circulating about the sound quality of the many variants of A80 audio circuitry is often outrageously mis-informed and completely wrong. In my opinion.
With that said, the very earliest, quarter-inch A80 R, clearly had the best headblock architecture. Sadly, that outstanding original design was very soon compromised, when Studer's commercial customers demanded ill-advised changes based on their program recording production needs.
> had the main capacitors done but are they difficult to replace
The term "main capacitors" is commonly understood to mean the filter capacitors (for voltage smoothing and energy storage) found inside the main PSU. On the A80 PSUs these were 8mm stud mounts, in values and form factors essentially no longer manufactured today, excepting by costly special order with large minimum order quantities. (Ask me how I know this.)
Those original OEM stud-mount main PSU filter capacitors were of extreme high quality and long-life. Yet after thirty-five or forty-five years in service (or storage), the only sensible approach is total pre-emptive replacement.
> Do I need to know anything else?
Yes. Understanding the A80 is a huge subject. Try to take an A80 owner familiarization course from a real Studer expert, and not one of growing numbers of fakes who are active preying on the gullible audiophile market. Importantly, find out if the person offering you training was professionally active in A80 machine support 35 or 40 years ago, during the time when Studer was building and selling this top-of-line product. I believe there are still some living, qualified A80 experts in the UK today.
> Then you can get a cheap machine and refurbish it all - all spares are easily available in the UK.
Sorry, but this is plainly wrong. Hundreds of authentic original A80 replacement parts have been no longer available (NLA) for decades now. (Again, ask me how I know this.)
Granted, many are selling A80 "rebuild kits" (as seen on eBay for example) but these are mostly full of parts that any real expert would never want to see installed into one of these fine machines.
The same is true for the extremely critical, high-precision radial ball-bearings, that require complete replacement in any A80 after every ten years. Not because those bearings have worn out. But only because the lubricants inside them have deteriorated due to age. Yet we see vendors everywhere globally, offering what they purport to be replacement Studer bearings, when they clearly are not. One hint is seeing someone touting the popular specification of an ABEC classification grade, a US based system that Studer never even used!
Yet of equal importance, is the exact lubricant specification (grease type) and its fill quantity, which varied greatly in THE SAME MACHINE according to the bearing's specific duty.
Then, there is the critical and exacting matter of adjusting the axial pre-load force after a new bearing has been installed. (Don't understand why measuring and adjusting axial pre-load force is critical in a precision guidance tape transport? You're not alone. The vast majority of even highly experienced tape recorder technicians that have attended service training programs at ATAE, have not been able to correctly explain what axial pre-load is on their course entry exams.)
Then, following bearing replacement, all path heights must be measured and corrected to a tolerance of about one-one-hundredth of a millimeter (0.0004 inch), using Studer factory gauging.
It should be abundantly clear that A80 transport re-building is hardly a do-it-yourself undertaking. If someone tries to assert otherwise, you've probably found one of the fakes. Caveat emptor.
How do you know if your A80 transport is ruined? Assess your machine's time base performance by doing wide-band flutter analysis. (More on this below.) Contrary to tape machine servicing folklore, traditional wow and flutter meters are not sufficiently helpful to providing insight into what the transport is doing to the time base performance.
> Look at capstan condition - full motor refurbishment is possible but expensive.
"Is possible" states it rather well.
Studer's sinter-bearing capstan motors were legendary for ultra low flutter. No rebuilder today can even begin to approach that level of quality and precision. So, many do not even touch the old sinter bearings and their corresponding extreme precision polished bearing surfaces on the ultra close tolerance matched capstan shaft. A scandal is how many motor shops "fake it" by refinishing only the capstan shaft's tractive surface and then returning the cleaned motor as "reconditioned".
Again, the only right way to accurately assess the critical time base performance of a tape transport is through what tape transport flutter expert Dale Manquen (and later, Audio Precision, an instrumentation manufacturer also here in the USA) termed high-band flutter analysis. (ATAE today calls this measurement technique wide-band diagnostic flutter analysis.)