Page 1 of 2 12 LastLast
Results 1 to 10 of 13

Thread: Changing between Studer A820 quarter and half-inch headblocks

  1. #1

    Changing between Studer A820 quarter and half-inch headblocks

    The Studer A820 has a built-in headblock identification circuit that immediately detects when you have installed a half-inch (or a quarter-inch) headblock. The tape tensions then automatically change over to the appropriate values. Those values can be the factory furnished defaults, or optionally, custom tension settings programmed in by you.

    It's with the A80 transports (and not the A820!) where the changeover from quarter-inch to half-inch format (and back) requires changing a host of hidden internal parts and a tedious, expert tension recalibration.

  2. #2
    Member Sponsor [WBF Founding Member] Mike Lavigne's Avatar
    Join Date
    Apr 2010
    Posts
    4,784
    Quote Originally Posted by Fred Thal View Post
    The Studer A820 has a built-in headblock identification circuit that immediately detects when you have installed a half-inch (or a quarter-inch) headblock. The tape tensions then automatically change over to the appropriate values. Those values can be the factory furnished defaults, or optionally, custom tension settings programmed in by you.

    It's with the A80 transports (and not the A820!) where the changeover from quarter-inch to half-inch format (and back) requires changing a host of hidden internal parts and a tedious, expert tension recalibration.
    thank you Fred. that is very helpful to know.
    Wave Kinetics NVS tt, (2) Durand Telos (1-Sapphire) arms, CA Gold Stat, Ort Anna carts, -2- Studer A-820 RTR (1/4" + 1/2").*Aqua Form dac, La Diva CD, SGM serv (2x) 30 tb NAS. *darTZeel NHB-18NS w/2 phonos, King-Cello. *dart NHB-458 mono blocks. EA MM7. *Equi=tech 10WQ, (10) Abso Fid PC & (2) Evo Acou PC. *Evo Acou 12' TRSC and 8m + 1.25m 'zeel' ic's, Tara Labs GME w/HRX 2m RCA's. *Tripoint Troy Sig, Entreq Sil Tellus + Poseidon, *Herzan TS-140 & TS-150, Wave Kinetics A10 U8's + 2NS, Adona GTX.

  3. #3
    Site Founder And Administrator Ron Resnick's Avatar
    Join Date
    Jan 2015
    Location
    Beverly Hills, CA
    Posts
    1,884
    This is very interesting, Fred! Thank you.
    Mono and Stereo - Senior Contributing Reviewer

    turntable: Thorens Reference (to come); tonearm: SME 3012R (to come); cartridge: ZYX Universe Premium X-SB2 (to come)
    tape: Studer A820 Mk II
    preamp: Aesthetix Io Eclipse with 2 power supplies (ordered); amplifier: VTL MB-750s
    speakers: Gryphon Pendragons (ordered)
    cables: MasterBuilt (not yet ordered); power: Benjamin Electric subpanel; JPS in-wall wire; Furutech NCF outlets; room: 20' wide X 25' long X 14' tall; treatment: ASC Tube Traps and Tower Slims; tweaks: Shakti Stones

  4. #4
    You are welcome, Mike and Ron.

    It's not a huge deal, but many owners aren't aware of it. The A820 owner's manual can appear a bit daunting, I think.

    Some people laugh at the idea of a one-week 820 operator training course. They almost always change that perspective after they have attended.

    Credit where it is due: Headblock identification for auto-switchover from quarter-inch to half-inch tension values (effected by the reel motor servo control circuit) was first seen in the Ampex ATR-100 introduced in 1976. The ATR-100 was very advanced for its time.
    Adolph Friederich (Fred) Thal
    Technical Director and Founder, Audio Transfer Laboratory http://audiotransferlab.com
    Managing Director, ATAE ataudioeng.com

  5. #5
    Member Sponsor [WBF Founding Member]
    Join Date
    May 2010
    Posts
    1,844
    Quote Originally Posted by Fred Thal View Post
    The Studer A820 has a built-in headblock identification circuit that immediately detects when you have installed a half-inch (or a quarter-inch) headblock. The tape tensions then automatically change over to the appropriate values.
    Would headblock i.d. be compatible with SHRO headblocks, Fred?


    Quote Originally Posted by Fred Thal View Post
    It's with the A80 transports (and not the A820!) where the changeover from quarter-inch to half-inch format (and back) requires changing a host of hidden internal parts and a tedious, expert tension recalibration.
    Thank you for the confirmation.
    Vbr,

    Sam
    SPQCV

  6. #6
    Member Sponsor [WBF Founding Member]
    Join Date
    May 2010
    Posts
    1,844
    Quote Originally Posted by Fred Thal View Post
    The A820 owner's manual can appear a bit daunting, I think.


    Quote Originally Posted by Fred Thal View Post
    Some people laugh at the idea of a one-week 820 operator training course.
    Not here!

    Quote Originally Posted by Fred Thal View Post
    Credit where it is due: Headblock identification for auto-switchover from quarter-inch to half-inch tension values (effected by the reel motor servo control circuit) was first seen in the Ampex ATR-100 introduced in 1976. The ATR-100 was very advanced for its time.
    Was entirely unaware of it -- thanks.
    Vbr,

    Sam
    SPQCV

  7. #7
    Member
    Join Date
    Jun 2011
    Location
    Taipei, Taiwan, Republic of China
    Posts
    34
    Even STUDER could make a mistake here. My A820 started recognize its head correctly about a year ago, after nearly thirty years in dark!
    Its 1/2" capability was built on a STUDER time code demo piece. The magnetic heads was from a 4 track A807. This configuration was similar to a A820 1/2" MR. (If configured with four sets of custom-built record/reproduce electronics, it has the potential of being a four track machine..... Just daydreaming...)

    This 4 track head will never be identified automatically since it was not listed in the table. Only A820 MR's firmware has proper parameters for 2 track 3.75/7.5 ips configuration. There should be no real problem: the missing part is only the factory default values of audio parameters. It will retain factory default tension parameters if 2 track 1/2" head was chosen at properly soldered pads. When alignment procedures were followed through and all audio parameters stored, the head block configuration will be recognized. The only difference is that 2 track 1/2" head's factory default parameters were invoked when rechargeable battery failed.

    Right now there was no real advantage of going 1/2"; two out of four tracks operation. I used it once in playing a 30ips 1/2" tape in 14" reel.

    Yeun-Jung Wu
    Attached Images Attached Images     
    Last edited by yjwu; 12-19-2016 at 06:32 PM.

  8. #8
    [QUOTE=c1ferrari;425584]Would headblock i.d. be compatible with SHRO headblocks, Fred?

    Hi Sam,

    Yes, ATAE SHRO headblocks for the A820 preserve the headblock identity function. Studer allocated a 4-bit data buss for this, so there were sixteen possible variations, provided that your installed firmware supports that many.
    Adolph Friederich (Fred) Thal
    Technical Director and Founder, Audio Transfer Laboratory http://audiotransferlab.com
    Managing Director, ATAE ataudioeng.com

  9. #9
    Member Sponsor [WBF Founding Member]
    Join Date
    May 2010
    Posts
    1,844
    Wow, Yeun-Jung -- I've never seen a 4-channel TC erase head on an A820 -- thanks for sharing!
    Vbr,

    Sam
    SPQCV

  10. #10
    Member Sponsor [WBF Founding Member]
    Join Date
    May 2010
    Posts
    1,844
    [QUOTE=Fred Thal;425792]
    Quote Originally Posted by c1ferrari View Post
    Would headblock i.d. be compatible with SHRO headblocks, Fred?

    Hi Sam,

    Yes, ATAE SHRO headblocks for the A820 preserve the headblock identity function. Studer allocated a 4-bit data buss for this, so there were sixteen possible variations, provided that your installed firmware supports that many.
    Excellent, Fred!
    Vbr,

    Sam
    SPQCV

Page 1 of 2 12 LastLast

Similar Threads

  1. FS: Studer A820 1/4" 2-track Master Recorder
    By Bruce B in forum Buy and Sell Forum
    Replies: 16
    Last Post: 04-20-2015, 03:20 PM
  2. Mark Levinson ML-5A Half-Inch Stereo Master Recorder
    By rockitman in forum Reel To Reel Tape Deck and Content Forum
    Replies: 13
    Last Post: 12-16-2014, 04:29 AM
  3. New recruitment: a 1/4" STUDER A820
    By yjwu in forum Reel To Reel Tape Deck and Content Forum
    Replies: 3
    Last Post: 09-10-2014, 10:08 AM
  4. New recruitment: a 1/4" STUDER A820
    By yjwu in forum Reel To Reel Tape Videos
    Replies: 0
    Last Post: 09-10-2014, 07:13 AM
  5. Studer A820, ATR, Ampex...!!
    By Bruce B in forum Buy and Sell Forum
    Replies: 4
    Last Post: 09-01-2012, 12:58 AM

Bookmarks

Posting Permissions

  • You may not post new threads
  • You may not post replies
  • You may not post attachments
  • You may not edit your posts
  •