STUDER A820 Master Recorder information

[useridchallenged]

For anyone curious about the last of the STUDER Master Recorders - the STUDER A820 - check out:

http://www.TheAudioArchive.com/TAA_Tape_Studer_A820.htm

This webpage represents the full text of the original STUDER A820 marketing brochure, along with some of my own comments on the machine, as well as full machine specifications from the service manual in the left column.  There is always much focus on the electronics of playback equipment (ie. tubes, solid state, capacitors, circuit topology...), but in the case of tape decks (and similarly turntables), a significant component of the sound quality is derived from the transport of the tape - not just wow-and-flutter, but scrape flutter, tension in the tape, and vibration/resonance induced in the tape.  When it comes to a precision transport, the STUDER A820 is truly a work of art - the metal casting and CNC machining more than make up for the lack of slick carbon fiber accessories <smile>.

Eric

[Ben]

Tape scraping on the reels is a easy fix ... Teflon them :)
The is the problem with consumer goods today ... lack of true
pride in the product that goes with the label "MADE IN THE U.S.A."
It more like today "Made in china" by Wang foo young Noodle and Audio equipment sales". The same goes with marketing music as we all know. That is why
I am glad to see the small internet sites promoting reel music and real hi-fidelity
equipment like here.
But I still think teflon could not hurt.

[useridchallenged]

Tape scraping on the reels is a easy fix ... Teflon them :)

Cute!

Actually, as a constant tension machine, the A820 produces a fabulous tape pack.

For anyone unfamiliar with scrape flutter, you can read briefly about scrape flutter at

http://en.wikipedia.org/wiki/Wow_and_flutter_measurement

and for a list of in-depth technical references, see

http://home.flash.net/~mrltapes/scrape-flutter-and-tape-compliance-bibliography.pdf

But to save you time, I quote the wiki:

Scrape Flutter High frequency flutter, above 100 Hz can sometimes result from tape vibrating as it passes over a head, as a result of rapidly interacting stretch in the tape and striction at the head . This is termed 'scrape flutter'. It adds a roughness to the sound that is not typical of Wow & flutter, and damping devices or heavy rollers are sometimes employed on professional tape machines to prevent it.

Fred Thal at ATAE has provided us with SHR headblocks (Single Head Reproducer).  With these modified geometry head nests, the only fixed element in the entire tape path is the playback head (no erase, record, or timecode heads, nor any fixed guides).  Every guide and point of contact otherwise is a rolling surface.  This really keeps scrape flutter to an absolute minimum, and takes the already-fabulous STUDER A820 sound to the next level (but I'm clearly "biased", every pun intended).

Eric

[docb]

As Eric notes, scrape flutter is created at the fixed guide surfaces in the tape path. We take the same approach with Technics machines that Fred takes with Studers, eliminating fixed guide surfaces where possible and replacing them with roller bearings where elimination is impractical. The difference is quite audible, manifesting itself as a smoother, more "flowing" sound.

With regards to tape scraping on reels, the best way to fix that is to adjust the machine for a well centered tape pack and chuck any bent flanges. Once it gets bent and consequently stretched it's very tough to get a flange to go back to laying flat.

[ironbut]

I really love Jay McKnights info (MRL tapes) on scrape flutter. Aside from Eric's excellent links you can check out this one from Dan Manquen;
http://www.manquen.net/audio/
I can personally attest to the effectiveness of Doc's tape path mods. The exchange of the top guides (the ones just above the pinch rollers) on my Technics for the tiny bearings and ceramic guides was very surprising to me. Being entirely out of the isolated loop ( with just the tensioner between it and the take up or supply reel) I assumed that it would only make the tape handling gentler and the tensioning more consistent. What I hear is a smoother sound and the noise floor lowered with more low level details revealed.
As Eric mentioned, the optimum flow of tape through the head assembly can't be emphasized enough. From the experience I had with the tape guides, I'd have to say that everything that makes contact with the tape is important. I guess when you think about how little mass the tape has, that's not too surprising.

[Ben]

For the doc. Can any of the fixed guides on the Otari MX-5050 be replaced
with rolling ones?

[Ki Choi]

Hi Eric:

Thanks for the A820 info.  After many months of anticipation, I will be placing the 1/4" half-track A820 next to the rest of the Studers collection over the weekend.

I am not as blessed as MikeL ;-( from this forum who had Fred Thal to help him with his A820 restoration project, I would have to repair (if needed), align, bias, and give it the TLC it deserves personally.

Your description of MkII version replacing the ceramic tape guides (one just the right of repro head and one long guide at the right of the capstan) makes sense.  Mine is a Mk I version and I am thinking about replacing the ceramic guides eventually.

One quick solution for the one just right of the repro head would be to transplant the roller guide from an A810 that seems to be the same part but I am stumped at the long ceramic guide's replacement.

Do you know a source for the roller guides for A820 other than the Audiohouse?
What other mechincal improvement did MkII have over the MkI version?

Thanks,

Ki

[ironbut]

Hi Ki, as Fred has pointed out to me on the Studer list in the past, sophisticated machines like the 820 are systems. As such, there's a delicate balance which has been the result of extensive research and testing. While I applaud your willingness to improve the performance of your Mk I, I think you would do well to pose your questions on the Studer list to find out from Fred just how big a project you're setting off on. You may be able to retain Fred's advice as you do the conversion yourself. You never know till you ask.

[Ki Choi]

Hi Steve:

Thanks for your advice.  It is my impression ...the moderator of the Studer List is not so kind to the DIYers... not like here!

However, I'll give it a try posting a question to the list after this weekend when I will have a chance to give the A820 a workout.

Also the List is not so user friendly for me to search for previous postings regarding the same subject... I am sure other A820 MkI owners have asked the same question before.

Ki

[ironbut]

I know exactly what you mean Ki. The list has it's ups and downs when it comes to audiophiles in general. It's that way with every 'Pro' audio forum. I find that the less information you give, the better. But most of the time, after I take a few posts of disapproval, I find out the information that I need.
 I think that most of these types of lists and forums have had their problems with audiophiles bringing up items of questionable value which degrade into debates that can be a waste of what should be a great resource. As a result, when someone seems to be "fishing" for opinions instead of asking for or presenting facts, the members do their best to discourage him/her. I do my best to contribute information that I'm very familiar with so I can answer any follow up questions. I think that that's one of the major differences between listener forums and producer forums. Members of Pro forums can't afford to experiment with musicians music or money. And experimenting is just about the most fun that an audiophile can think of. So if you ever wonder why it's so easy for the members of pro forums to spot an audiophile, it's that the mind set it is very different. We're there to have the best sound and they're there to make the best sound. Add to that, the best sound is often not the most pleasurable sound.
That, at least, is my take on the situation. I'd be interested in the thoughts of other members who've jumped into these "Pro" audio forums or lists. Please don't turn this into a " This is what happened to me!" list unless it's an approach that had positive results. I'd love to hear from the Pro's among us how best to avoid stepping on any toes when we are trying to obtain info from these lists. It's appropriate that the original poster of this thread is a highly regarded professional himself.

[Ki Choi]

Hi Steve:

Thanks for your response.  I agree with what you said above.  It seems the fastest growing group of analog R2R machine fans are the audiophiles whereas there are only handful of pro archivists and tape transfer people who still use master recorders in regular bases.  If the goal of the List is to preserve these fine machines for the future generation, non-pro audiophiles and DIYers should be encouraged to participate in the discussions.  Just my two cents.

On the other hand, I should have taken a picture of an A820 loaded in a Toyota Prius for a ride from my work to home this afternoon.  It probably was the first and maybe the last a 200 lbs Studer A820 was transported in a such a small vehicle.  The back hatch was not closed all the way but it made home without an incident.

All the other Studers I have collected so far required some work to get them to work properly.  But the A820 is performing flawlessly from the moment I checked the cards and turned the power on for the first time.  The VU meters needed the light bulbs that I already had them on hand for A810 spares.  Even all the pushbutton T5.5 lamps were all good.  The recorder is not perfect cosmetically but it is in excellent condition.  I am also happy to learn all the audio cards in A820 are the same as the ones for A810.

In looking further into the ceramic guides, I realized my A820 with SN: 1131 already has the roller tape guide described in the manual as the Scrape Flutter Roller located left of the record head.  The ceramic guide right of the repro head turned out to be the Tape Lifter that pushes the tape away from the repro head during spooling.  The last cermic guide positioned right of the capstan was a dummy head where the time code head would have gone.

Thus, I have answered my question...

It will be interesting to align, adjust, and bias the A820 to the factory spec and compare its performance to A80RC, A810, A807, and the Sony APR5003 in due time.

Ki

PS: Re-read Eric's original post on SHR headblock.  I'd like to see a photo of the headblock to ease my mind but it seems in addition to removing the erase head, record head and moving the repro head to where record head used be (my guess), the mode must have included replacing the cermic tape lifter with a roller (it does touch tape during play), and also removing the dummy timecode head would be a part of the physical changes.

[Ki Choi]

Eric had asked me about my Studer A820's software version:

38/86

Thanks,

Ki