INTRODUCTION:
I am pretty sure this is the last of my beloved REVOX & STUDER complete equipment. I owned and operated an audio post production studio/facilities for many years and the backbone of our gear was STUDER but we also had a few pieces of Revox and some nice old English QUAD gear. This A78 I have held back from finding a new home, sentimental reasons I guess...
For me, Revox (and Studer) and not just all about the electronic engineering and the sound they produce but how they were mechanically engineered and built - just wonderful! An outer wooden frame (REAL wood) and a solid metal frame along with that distinctive diecast rear heatsink/back panel. So organised, well laid out and (from my point of view) very easy to work on, if this was ever necessary (which it wasn't because this gear just keeps on keeping on albeit after 50+ years that situation may well change, nothing lasts forever - particularly electrolytic capacitors!
HISTORY:
REVOX & STUDER are one of the most well known names in the world of high end audio reproduction, particularly STUDER in the professional audio world and it's "little brother" which was aimed at the semi-pro/domestic market. In our previous audio post production facilities we used the professional analog studio equipment in the STUDER range, namely the A810, A820 (beautiful 1/4" tape machines) and to a lesser extent, the REVOX A77 and B77 machines, these being intended more for the "semi-professional" marketplace with lesser facilities and abilities.
This A78 stereo amplifier was targeted at the high end domestic analog audio market, as part of a "desirable" trio, being the A76 (tuner), A77 1/4" reel to reel tape machine and this A78 stereo amplifier. Often folks upgraded their A77 to the later B77 which was overall a "better" machine and could run at 15ips, something the A77 lacked. Very useful (to achieve the highest possible quality recordings) to record/playback at 15ips but most commercially released tape recordings would run at 7.5ips anyway. As an 'aside', our beautiful "dream machines, the A810 & A820 were often run at 30ips! That was a sight to see, the tape literally flies from supply to takeup reels!
Woops, I have become side-tracked - I just love tape! So getting right back to this A78 ...
Most of our high end classic gear has gone but now it is time for this lonely A78 to find a new, appreciative home within which to reproduce beautiful music! Team it up with some classic loudspeakers (with "class" of course, KEF's or perhaps the Dali's I am soon to advertise) and perhaps even the wonderful B795 tangential short tonearm turntable (another wonder at the time)
As with any great audio equipment with "history", these things normally do not come cheaply but my focus is on finding a new appreciative home, not as a money making venture and the asking price reflects this - fair and reasonable.
I never offer an item such as this with the basic "here's a great amp - buy it!" but instead I go deep, sometimes very deep, in my descriptions - observations and of course test results ...
Brew a coffee (or tea), sit down and read on about this piece of wonderful analog audio design technology from a company that knew how to design and build audio equipment "works of art".
REVOX - Stereo Amplifier
Designed in Germany (Willie Studer)
Made in Germany
Model: A78 MKII
1970's era
Plenty of technical information about these amplifiers online but in a nutshell ...
Multiple AC power input voltages, easily selectable at the rear panel (110-150-130-150-220-240-250V)
AC input power socket uses a Euro standard socket, NOT something that you see very often these days but don't stress, if you do not have the correct lead I have an adapter 
She cruises at 40W RMS per channel, doesn't even break a sweat, although of course most folks (who consider their neighbours) would be running at much less power than this.
Multiple inputs, pretty standard range from 2x Phono (Turntable) one being for Ceramic cartridges! and the other Magnetic (MM), Aux, Microphone, Tuner, Tape - these are all on standard RCA sockets with the exception of the Phono Ceramic & Aux inputs, which use DIN EURO 5 pin 180 degree sockets (like a MIDI connector) as a common input with a small slide switch next to these sockets so that the user can select which one to use (most likely Aux these days!)
Active pins on the DIN EURO 5 pin 180 degree sockets are 2, 3 & 5 with pins 1 & 4 having no connections.
A couple of extra outputs, Tape Out and Tape Monitor, again on RCA sockets
Two sets of loudspeaker outputs, A & B, and although they look "weird" they are in fact DIN 2 pin loudspeaker sockets (one flat pin and one round) I think these should be readily available from most distributors but if you are stuck, just as me for my little "test plugs" which are these DIN Speaker plugs with an EXTREMELY short tail so I could connect up different speakers easily. Those 2x DIN Speaker plugs I used for testing are included if you want them, ask me when ordering (order notes can be left in the order checkout area of my website). The major drawback with these DIN speaker plugs is the small diameter cable that can be fitted from the rear. If you use something like "monster cable" for your loudspeaker wiring, you will need to develop some sort of adaptor that works in conjunction with these DIN connectors.
At the front panel is the distinctive Studer/Revox knobs and Grey front panel - signatures of their products. All knobs are concentric (have two functions) and are original, no 3rd party replacements here! The Aluminium push buttons (push ON push RELEASE) are the input selectors and way over on the far right, the ON-OFF button.
Just above that button is the Red power ON indicator
Nice touch from Revox, a spring loaded drop down panel (with the REVOX logo on it) allows easy access to an array of sub-controls from the front panel ....
All inputs have individual input level controls, on EACH CHANNEL. There is also the loudspeaker output selector (push button A or B non-interlocked i.e you can run both A & B outputs at the same time) If you do this, keep in mind that you shouldn't go below 4 Ohm impedance in total (8 + 8 is fine but 4 Ohm + 4 Ohm is not advisable)
DIMENSIONS: 410mm width x 160mm height x 230mm depth OR 255mm if the knobs are included ... basically this amplifier is similar to a large brick!
NO topside venting is required as all power output cooling is via the diecast rear panel, this means that "stacking" of your audio gear is not complicated by this amplifier.
WEIGHT: 8Kg
So that is the very basic description of the A78 design and capabilities .... now I will talk "at length" about how this gear was put together ... and comments about the condition of each section
COSMETIC CONDITION:
The A78 has a solid metal frame which slips inside a wooden outer case, secured by 4x bolts on the underneath
First up ... let me tell you about the WOODEN "SLIP CASE"
The outer wooden "slip case" does need a cleanup if the purpose is to restore this A78 to it's former glory days.
This wooden case looks to be a plywood with REAL wood veneer, finished with a lightly applied matt or stain clear coating.
Please take a look at the case photographs, to explain ...
The topside cover obviously needs a clean back and fresh protective coating or lacquer applied. The marks on the top look to be fading/failing of the original sealant (if I apply liquid, it soaks into the wood underneath) and there are some light marks/scratching. None of these are serious and it is my believe that this top section can reasonably easily be bought back to almost original condition.
The front and rear photographic views show that they are fine.
The Right side panel though has a small but noticeable concern, it looks as though something has collided with this case at the rear. I suspect it happened while we were moving a lot of equipment out of our old premises, another piece of gear sliding across and colliding with this A78 ... fortunately the "dent" in the wood is not very serious, just a bit unsightly - it depends upon your tolerance for such imperfections. I guess some attempt could be made to rebuild or pack this area, it is after-all quite small but (for me at least) would it really be worth all the trouble?
You may also be able to see the metallic shielding sheet inside the outer case and most importantly, the rear panel labelling strip. This labelling strip is so important as it easily identifies the various rear connections while looking down from above, in fact it is the only way to determine which port does what because the diecast rear panel has no labelling other than the REVOX identification label.
That's enough about the wooden outer "slip case", let's take a look around inside (and make some basic measurements)
FRONT PANEL
All knobs and buttons are originals, not 3rd party replacements. There is no wear apparent to any of the labelling, either above each control or on the concentric knobs themselves. However I can see some light wear to the continuous White line that runs right across the lower section of the front panel.
The dark Grey background colouring is consistent and smooth but again, in certain light, I can see just a very slight "ripple" around the centre of this panel - not a major issue but to some this may be important. All knobs and buttons are very clean and of course shiny!
The pull down top panel (which reveals the fine level controls on each channel, the loudspeaker selector and one of the fuses) is in very good, clean condition with no wear to the Blue ReVox logo and identification labelling below it. The door-panel action is smooth and positive (the spring works well!)
Special note: Inside this panel you are greeted with (for example) TAPE 1 & TAPE II level adjustment controls. This is how ReVox describes each channel throughout this equipment, it isn't the Left or Right channel but Channel I or Channel II
REAR PANEL
The one piece, diecast metal rear panel is in very good condition. No physical damage, all connectors and the Brass rivets are clean and shiny. AC input male 2 pin socket is also clean and the pins are not oxidised at all. All ports (mainly RCA sockets) are clean and relatively shiny for good contact.
AC input power socket uses a Euro standard socket, NOT something that you see very often these days but don't stress, if you do not have the correct lead I have an adapter 
THE FRAME - CHASSIS - THE ELECTRONICS
Typical of Studer-ReVox products, this A78 is built like a battleship with sturdy, thick, folded sheet metal. Once removed from the wooden outer slip cover, there is no top or lower panels covering everything - this girl doesn't mind showing you everything she's got! Well laid out modular type construction with the heaviest component (the AC power transformer) mounted centrally which provides a nice balanced feel when lifting. Nothing worse that picking up a heavy amplifier and it goes lop-sided on you and risks crashing to the ground!
Inside are various modules, often with edge connectors and/or small spade terminals for the interconnections. Not a lot of soldering for the interconnections, this makes removal of modules for servicing or replacement quite a simple task. Of course the boards are populated with European sourced components and I have carefully looked over the boards both topside and underneath to check for signs that "someone has been here before". I don't recall us ever having the need to service this amplifier but it was a long long time ago now!
All components appear to be originals, thank goodness! I once was offered a different ReVox machine that had been turned into an "abomination" by someone using inferior Asian sourced components to service the gear - just terrible!
Now I did say "thank goodness" but this is a two edged sword because although the original components are in place, nothing but nothing lasts forever and electrolytic capacitors (and a lesser extent trimpots) will eventually fail (usually the electrolyte just dries up, we all do that after a long time!)
Please keep this in mind! While the amplifier is as described currently, it will eventually have issues due to age - next week, next month or in ten years but it will happen!
TESTING:
AC input voltage selector is set to 240V
I checked all of the accessible fuses to ensure nothing was amiss, all good here.
This amplifier has not seen AC power for a number of years so my first step in testing was to power up the amplifier via my Variac, slowly increasing the input voltage over time (minutes) and making sure nothing nasty was about to happen.
Nothing nasty happened!
Powers ON but no panel lamp indicating ... not unusual for old incandescent lamps. I checked the voltage to the lamp (White - White wires) and all good here but no lamp is alight. It looks as though the lamp filament has gone open circuit, the issue here will be the voltage - this is a 36V @ 50mA lamp, which is just a bit weird (and difficult to find - best of luck!) So the amplifier is ON but you wouldn't know it, yet.
Next I checked the big electro's in the power supply, designated C906/C907/C926/C927 (5000uF @ 50V), these are to the right of the central AC transformer. I measured voltages 39~40V or a supply rail of -40V and +40V which is pretty good, the schematics indicate this should be a dual 41V supply.
I then checked the A & B loudspeaker outputs, there should never been any significant DC voltage at all - if so, there is great risk of cooking the loudspeaker voice coils. I know, because it happened to me once, never again! No nasty voltages were found at these loudspeaker outputs, just a "kick" measured at turn on. These amplifiers have no relay protection so when this A78 is powered up, you will not hear a "click" as the relay in other protected amps "pulls in"
The following tests were made over a few hours and are very basic but should give an overall idea of this amplifier's condition and what may or should be done to get it "up to scratch".
Connected my Leak loudspeakers, the easiest for me to access at the moment.
Watch out how you connect the loudspeakers, its been a long time and I had forgotten which connector is which for the loudspeakers - in my opinion it isn't all that clear. The A loudspeaker outputs run horizontal not vertical (I initially wondered why I had only one channel output!) Problem (self created) has now been solved.
At turn on, there is practically no sound except a short low level 'buzz' which then disappears - so that short spike in voltage at the outputs does not show up as a loud clunk or anything like that (thank goodness)
Keep in mind that this is by no means an exhaustive test and it is intended to only discover the basic current running condition of the A78 ...
I first used the TAPE and then the TUNER inputs, line level test source was my TASCAM broadcast CD player. I had good output (meaning clean and plenty of level) on both channels although I found the STEREO - MONO I II switch a bit touchy to maintain a stereo output. I also used those hidden level controls and found them to be a bit noisy in operation and some were quite "stiff"
Next I moved to the much lower level input, the turntable or phono input. Same sort of issues as with the above tests although funny enough, the stereo control wasn't as "touchy" In fact I was particularly impressed with the audio quality through the phono stage, quite similar to my wonderful NAD phono modules. That said though, I was surprised to not find a signal ground point on the rear panel so I had to do this manually otherwise I ended up with a low level hum loop.
I did not test the inputs via the DIN 5 pin sockets, it just didn't seem worth the effort to wire up a suitable plug for those.
While checking the above inputs, I also activated the push buttons, in particular the PRESENCE, LOW & TAPE MONITOR (kills the loudspeaker output) I also changed the tone controls over on the right hand side of the panel and all was good there as well with no audible noise or "crackling" when the controls were changed. Another little ReVox thing here ... these tone controls are not continuous sweep types but "step switches" as the knob is rotated.
CONCLUSION AND FINAL INFORMATION
I know I know, you must be exhausted after reading through all of this description and detail - it's a "me" thing and it is how I have always operated ...
Overall, even after quite a long period of disuse, this A78 is in really good shape AND it still works fine although (as noted above) it really should have some "sprucing up" to bring it to A1 grade, it deserves it!
That STEREO issue and also those stiff, "a little noisy" level pots most likely need a clean with a good quality switch/pot spray cleaner. This is a pretty common issue with older amplifiers in any case. The ON indicator lamp is a different story, now that may present some challenges due to the working voltage of the lamp. Cosmetic "tidying up" of the wooden outer case would not be too difficult and the end result would be stunning!
SHIPPING INFORMATION:
Keep in mind that I normally ship anywhere WITHIN Australia at no cost when orders exceed A$75 value, this amplifier is no exception and it will be shipped safely at no additional cost.
In the case of this A78 ONLY, I will also ship internationally (except USA which is on my Black list due to tariff uncertainty) at absolutely no additional shipping costs (but this does not include any duties or levies placed by the receiver's custom border authorities). This A78 would be sent using Australia Post (standard International Service) with full online tracking while the amplifier is in transit.
This international free shipping offer is made because (from my past experience), almost all of my ReVox and Studer went back "home" to Europe, with little interest here in Australia.
SHIPPING UPDATE: A number of interested folk who live in Australia have pointed out that as shipping is free worldwide, but shipping within Australia is of a lower cost by comparison to International destinations, can I make a price adjustment for this?
After careful thought I can see their point and have decided to enable a "coupon code" for use by AUSTRALIAN resident buyers only - in the checkout area, if you add the code AUSTRALIAN SHIPPING then A$125 will be automatically deducted from the order total, making the price of this ReVox A78 just A$465 with the free shipping included.
