Studer A80 RC

SeleniumFalcon · February 15

Well, at long last the A80 is ready for some listening. I replaced the dual set of bearings in the tape guide roller and the pinch roller and completed the cleaning and polishing of everything possible. I was able to source the original paint color used in the roll around cart and section by section repainted it. I've replaced dozens of metric hex head bolts and polished and waxed the two section top plates. I adjusted the tape tension, set the audio power supply voltage and installed the NextGen audio playback cards. These were designed by Jeff Polan and Charles King and significantly lower distortion, raise dynamic range and eliminate unneeded components. My wife and I began listening to the new Tape Project recording of the Chieftains and simply were floored, we have both heard them live on several occasions and this was amazing. I think I'm still dazed by how good everything sounded. We went on to George Shearing and Nat King Cole and then Oscar Peterson. These are all carefully done master tape copies and I've been saving them for when I had just the right deck to play them. My wife said, "Good day in audio land".

SeleniumFalcon · February 15

SeleniumFalcon · February 15

SeleniumFalcon · February 15

Clipdat · February 15

More lovely photographs, thank you!

SeleniumFalcon · February 15

SeleniumFalcon · February 15

SeleniumFalcon · February 15

Clipdat · February 15

Beautiful room and gear.

VR3 · February 15

Looks awesome! I may have missed it but what speakers do you run Ken?

Jetmaker737 · February 15

I am so jealous! Beautiful. Wish I could hear it. But then again, no. I'd probably kick my deck to the curb and/or do something that would entail spending a lot of money.

maxward · February 15

Excellent work, Ken.

SeleniumFalcon · February 15

Thank you, I appreciate your comments. It is a real pleasure working on this deck, the 316 page service manual is extremely thorough. Those red LEDs you can see in one of the photos tell the operator what is functioning in any mode. By looking at the manual you can tell where a problem might be if something's not working correctly by looking at the LEDs. I was able to source the correct spring gauges for setting the proper braking force and two extender boards. It took a while to get everything sent.
I have two pairs of speakers that I rotate. One is the Martin Logan CLS II and the other are the Harbeth HL5 Super, anniversary edition. I use a Janis W1 with both sets. They are great speakers.

SeleniumFalcon · February 16

I found a photo of the deck as I first saw it, no improvements had been made.

heiney9 · February 17

Another excellent thread...fascinating. I learned a lot and thanks for the excellent photos Ken.

H9

Joey_V · February 17

Most excellent

SeleniumFalcon · February 17

Thank you!

SeleniumFalcon · April 4

I've made some changes to the A80. I had a local plastics manufacturer build a custom dust cover for the deck. They did a great job.

SeleniumFalcon · April 4

I replaced both of the spooling motors with new ones. So, now all three motors are new and are extremely quiet and smooth running. Here is a photo of the old ones:

SeleniumFalcon · April 4

Another photo:

SeleniumFalcon · April 4

I was able to add quartz control to the capstan motor drive, courtesy of the Pievox company in Germany. This brilliant design was done by the late Ernst Schmid and stabilizes the speed accuracy of the transport:

SeleniumFalcon · April 4

I was able to add a super-regulated voltage stabilizer to the audio section, courtesy of the Master Tape Sound Lab located in Greece. This was designed by Todor Dimitrov and provides a state of the art, low noise, broad frequency low impedance regulator stage:

This stabilizer combined with the Next Gen audio playback boards is amazing.

JayCee · April 4

That has to/will be the nicest A80 on the planet!? Don't be modest

...at least top 2%. I would've typed 'best 1%' but have to leave room for improvement.

If not out of line....what does a custom plastic job run and did you or they do the design?

SeleniumFalcon · April 4

Thanks, I have one more modification to add. It is an amplifier for the tension sensing circuits, to make the tension corrections quicker and smoother. I just have to muster the gumption to get inside and install two small circuit boards. The dust cover was done by Plastec Profiles in southern PA and I gave them the dimensions and their first design was to use individual pieces and glue them together. Instead I preferred a molded complete top, front and back made of a single piece with the two sides cut and fitted into the upper piece. They told me this was a more difficult procedure and might take more time. It took a little more than two weeks and cost about $260.00 which I felt was reasonable.

SeleniumFalcon · August 13

A couple of fairly minor things that I wanted to take care of was a tendency for the left hand tension rollers to squeal when rewinding or fast forwarding. This involves removing the old ball bearings, the smallest I've worked with, and replacing them with SKF 623-2Z made in Italy. I first tried some bearings I sourced from McMaster-Carr and they were very low friction but were a bit noisy. Then I got some of the Italian SKF sealed bearings and they were a bit higher in friction, but very quiet.

SeleniumFalcon · August 13

The second problem is really nitpicking, this deck has a self-contained clock that keeps track of the operating time elapsed. Normally there is a heavy chassis plate that covers up the complete lower front of the deck. But, in order to provide a more direct output the NextGen playback boards have the outputs on the front right where the circuit boards are located, instead of the stock cables leading to the back of the chassis. This means the covering door is left down and I can very slightly hear the clock ticking. So far I've tried using thick cloth rolled into a cylinder and stuffed in the front opening and that reduces the level quite a bit. I can get inside the chassis and disconnect the power to the clock, but that goes against my audiophile, keep everything working as designed, neurosis.

newbie308 · August 14

I wonder if there is a suitable needle bearing assembly that would be both low friction and quiet.

SeleniumFalcon · August 14

I don't know much about that type of bearing. If I remember correctly the bearing is 10mm wide, 4mm high with a 3mm center. I'll do some searching on those, thanks!

newbie308 · August 14

Another thing to look at is that some ball bearings are available in various amounts of preload. Basically, high precision bearings have negative clearance between the balls and the inner and outer race. A bearing supply house like Kaman or Motion Industries should be able to investigate if that bearing is available with various degrees of preload or even cross reference it to a bearing that does. Another thing to consider is the tolerance of the bearing bore to the shaft and the tolerance of the bearing housing to the outer race. If the bore of the bearing is loose on the shaft, it may be spinning on the shaft and that would definitely squeak. If the fit of the outer race to the housing is too tight by even -0.0005 inches, It could cause the bearing to cog. A set of telescoping bore gauges and a micrometer that can measure to 0.0001 inches is invaluable when selecting bearings for precision applications.

SeleniumFalcon · August 14

The subject of which bearings are best for Studers is very similar to which driver is the best match in a Polk SDA speaker. There tends to be two schools of thought. One, is the choice of bearings should always be ones from Studer directly (this was obviously easier when the company was still in business) since they knew exactly what bearings were best for each design. The second school of thought is that Studer never made bearings, they just bought from suppliers and did some measurements and picked the ones that met their qualifications. In other words there's nothing magical about the Studer bearings, they were selected like everyone else does. There is a very thoughtful thread on the Tape Project forum that delves into how bearings effect recording and playing characteristics. When I opened up the two spool housings I could see that the original lubricant that was in the original bearings had leaked out of the sealed case and was around the shaft. I think the bearings were just out of lubricant and started making high speed noise. I used an automotive stethoscope to pin point where the noise was coming from. The right hand tension rollers were very quiet while the left hand ones were noisy.
There are two Belleville preload spring washers on the lower ball bearing that give the correct amount of vertical tension.

This is why tape recorders are so interesting, they are tuned systems, just like a good sounding speaker. Every time I open up the Studer service manual (330 pages) I appreciate something new.

Studer A80 RC

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