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Messages - stellavox

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Hi Kostas,

As you are probably aware, The Stella's used what Nortronics called "B case" heads, a "standardized" shape that a few manufacturers made.  They used Bogen (German) originally for PB and Record with Wolke erase, then switched to Nortronics PB/R.

I believe the only entity still making heads is AMR? or something like that in Europe - they made the later butterfly heads for the Stella SM.  O yeah, I believe that Flux Magnetics also makes B case units - at least playback.

Depending on how many you need, I have some record and erase Pro Nortronics.  Want to keep the few PB heads I have as there are no more.  Also suggest contacting John French to see what he may have.  I also have a few Pro nortronics heads that are fine but could use a relap.


Knowing what it's like to get inside the machine I only want to (have to) do this once.



Tape Project Machines / Re: another mx5050 thread
« on: May 02, 2017, 06:43:17 AM »
Congratulations drdeaner on your DIY efforts - and RESULTS!

Only suggestion would be to try a few other op amps in place of the 1028 - like the LME49710, or what I feel is the best (but expensive) - OPA627/827


General Discussion / Re: Retiring!
« on: December 26, 2016, 06:49:14 AM »
Boo Hoo - There goes the neighborhood!

Thanks for EVERYTHING you've done for us Doc!  We all can/should/deserve to move on.

However, aren't all the dupes made / packaged / shipped from your place?  If so, who will take that over? A move in the offing?

Best (especially of health) in your "retirement".  (BTW - will never forget your last VSAC)


Keep your heads clean and your tails out

Tape Tech / Q
« on: November 05, 2016, 04:42:32 PM »

This is VERY interesting.  If you think about it - how do you TURN OFF playback or record equalization when playing back or recording a dub?  Ever seen a deck that could do this? The circuits I've seen ALWAYS have SOME EQ components switched in - you can switch in different value components to change that a bit  but because the parts are typically an integral part of a feedback network in the amplifier circuitry - SOMETHING has to be there.

I'd opine that it MAY mean whomever made the dub applied the "original - or same" EQ to the copy.

It should be "really easy" to determine if the dub is flat or equalized "somehow".  Listen to it using, say with NAB EQ switched in and let us know how it sounds.  If "flat" DOES mean un-equalized, then the tonal balance will be WAY off.


For "distributing" the 5 volt logic power around certain of the A8.. series of recorders, Studer took the "interesting" path of creating a higher voltage, maybe 6 volts on the power supply board, and then "dropping it down" via a diode, or in some cases a diode / dropping resistor / smoothing choke ON THE INDIVIDUAL BOARDS where logic power was needed.

On the two 812's I "rebuilt", and other models I've worked on,  some electrolytic filter caps on the individual boards went bad OR LEAKY and went as far as charring the dropping resistor / choke.

I suggest checking the logic voltage ON EACH BOARD AFTER THE DROPPING "NETWORK" and see if it is within spec.  Better yet, as many have mentioned in other posts/forums, identify and replace ALL THE CAPS ASSOCIATED WITH FILTERING (only a few on each board - use 105 degree replacements - remember that some boards had caps for the +/- 15V also.  After that, the units worked fine and in some cases readjust the logic voltage DOWNWARD (out of the regulator card) because "something(s)" (combination of leaky caps?) was dragging it down.


Can't emphasize enough that these machines, being a MINIMUM of 25 years old AND many/most with QUITE a few hours on them, "DESERVE" a FULL electrolytic FILTER cap replacement - especially if you "think" you plan to use the deck "for many years into the future".  A trick I used for replacing the big (hard to find) stud-mount caps (because new "snap-in" equivalents are physically smaller) was to cut the case (with a hacksaw) maybe an inch from the bottom; remove the guts / clean out the case and epoxy in the replacement - making sure to arrange the terminal positions to minimize wiring distances.  Yes it takes time, but only should have to be done once, AND should really add to your "peace of mind" regarding your ongoing relationship with the deck.  Finally, if you can't do this yourself - MAKE SURE any deck you buy has had this done.

Reel to Reel Tape Machines / Re: Parts for Studer A812
« on: September 11, 2016, 05:58:48 AM »
Based on my own experience, you are going to have problems finding parts - especially "cosmetic" parts.  A Chicago-area friend was parting out a -12 and may still have some - [email protected]



MCI's like the JH-110 series have been popular for this - However they are BIG - do you have the space?

A77's are another thing entirely.  You'd have to "play with it" to see if you can get the "sound" you want.  And stock their basic sound "quality"doesn't approach the pro decks.


Reel to Reel Tape Machines / Re: Revox B77 conversion to 1/4 track
« on: June 20, 2016, 07:40:40 AM »

I opine that you forget trying to modify your high-speed, 2 track machine.  It is much less "common" and more valuable than the slow-speed, quarter- track version.  Sell yours and buy the other.  And while looking for the other "B" you could also look for a PR99, the successor to the A/B77.  You might just get lucky!


Tape Tech / Re: STUDER A810 SPOOLING MOTOR CONTROL PCB 1.810.760-82
« on: June 02, 2016, 09:29:55 AM »

Please let us know if Ki's suggestions fixed your problem. 

I did run in to a similar intermittent problem on an 812 I worked on AFTER replacing the caps you/Ki mentioned.  The 812 has another board called the Tape Deck Periphery Interface, just before the Spooling Motor Controller board you mention .  On the Interface board, Studer revised the time constant on the 812's left tension, hi-pass filter circuit (R43/44 around IC20) from 4M7 in parallel with 6M8 to a single 910K resistor.   This eliminated my problem with large reels but it would still occur (infrequently) on 7 1/2 ips with a smaller 7"reel on the supply side.

Of course the deck probably shouldn't be used with small reels!  But, I happen to have a few of those wonderful, prerecorded remnants from the mid/late 1950's.


Tape Tech / Re: Studer meter bulb replacement
« on: December 30, 2015, 08:57:34 AM »
Of course the bulbs on the two 812's I rebuilt were burned out.  Locating replacements at the time uncovered "exorbitant" prices on NOS units.  Have some experience with LED's, so replaced "them with those".  Found that Cree C535A-WJN-CU0V0231's (110 degree dispersion - available from Mouser) worked just fine.

Removed the bulb sockets and wired TWO LED's (in SERIES - works just fine) reusing certain of the existing bulb socket mounting holes.  Positioned the LED's as far apart as their leads would allow and (of course) pointing "forward". 

The "repair" provides plenty of illumination; no heat; BUT does look "whiter" (versus "amber") which could be a problem for purists - haven't looked to see if an amber LED is available - nor tried some kind of translucent "filter"


Picked up and “reconditioned” two Studer A812’s (a whole story in itself) and along the way decided to add an “outboard” K/C pre directly to one of them.  Mounted the power supply components inside the back panel and the pre box directly underneath the front “cowling”.  “Wired out“ the PB head to the pre. 

Got everything working fine but then was “bothered” by the fact that the VU meters on the overbridge couldn’t work in playback – which of course is a problem with “wiring out” ANY PB head to an external pre.  Tried a number of “schemes” (like bypassing the repro cards and running the signals directly into the line amplifier cards) but settled for the method described below because it involved the MINIMUM amount of modification and wiring.  Note that this "mod" should also work on the "similar" 807/810/820 series.

To get the meters to work, you (of course) have to run a “hot” lead from each external pre output channel back into the transport.  I elected to bring the leads right up to the VU Meter Amplifier card/assemblies mounted on the overbridge.  If you look at the schematic for the VU card (1.820.730-81) you can feed a signal into the VU driver IC-1 by lifting the minus end of C2 and connecting the signal right there.  HOWEVER, now you’ve lost the ability to monitor the “line” or record signal.  So I added/mounted a DPDT toggle switch on the blank panel just to the left of the Left Channel VU Meter assembly.  In the “up” position of the toggle switch, the signal from the external tape pre is routed to the minus end of C2 (actually replaced it with a higher voltage unit); in the “down” position, the signal from T1 on the VU meter card is routed to C2.  Found that I needed a voltage divider to isolate/attenuate the signal coming from the external pre.  Used a total value of around 50K ohms. You can figure out the divider ratio based on the output of your external pre but do suggest adding a screwdriver adjust pot as the "lower resistor" to allow for meter calibration.  The wires were very easy to run from the overbridge to the external pre.  Found that I didn’t need a separate ground wire.  Everything now “looks” and works fine.  Whew!
This is a way to get the meters working if you have your external pre mounted “on” the transport.  It got me thinking that if you did want to use the transport’s meters with a “remote" outboard pre, you could add a (stereo) jack on the back of the meter bridge, and bring the pre’s output signals (and ground?) to a plug that mates with the new jack.  You’d have to put the divider someplace – inside the bridge would probably make the most sense.  Could add the DPDT switch I mentioned, or try finding a jack that may have the switching function built in; like the Neutrik NRJ6HF series.

Happy New Year


General Discussion / Re: PFO 2015 Writer's Choice Awards
« on: December 14, 2015, 06:28:41 AM »
TOTALLY Agree with Myles - "experienced" the tape at his place yesterday.  Dave Grisman's Mandolin is the best I've ever heard

Congratulations (and Merry Christmas) Guys - and dolls. 


General Discussion / Bulk Tape Erasers / Erasure
« on: October 16, 2015, 09:14:53 AM »
A fellow tapester mentioned a problem he's having - trying to erase a pre-recorded tape using a "bulk tape eraser".  I realized that I'd experienced the same problem and thought I'd throw it out to youse guys.

First of all; let me describe what I'm talking about, for those of you who may not be familiar with the term.  A "bulk" tape eraser is a big box, typically with a little post on it, that you can "mount" a whole reel of tape on.  You plug the cord coming out of the big box into a wall outlet, push down an "on" button somewhere on the box, and typically hear a hum as the GIANT AC ELECTROMAGNET inside the box erases the tape - also demagnetizing ANYTHING ELSE within a 2 foot? radius.

The erasers I had could only handle 7" reels max and I'd lost any instructions: so I tried various techniques - like spinning the reel slowly (while pushing the button) - maybe one revolution on 5-10 seconds; then turn the reel over and do the other side.

My friend mentioned that he tried this/these but gets a "whomp - whomp - whomp.... sound when playing back the "supposedly" erased tape.  Yep, I remember that. SO what are we doing wrong / were do we go from here????



General Discussion / Re: R2R links
« on: September 10, 2015, 01:35:25 PM »

In your links, do you include the Craig Stark article from an "old" Audio Amateur magazine on the A to Z's of setting up a tape recorder?  If not, I have the pages in individual files - now if someone a lot smarter than me could put them together into ONE file.


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