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NAD/new nightstand day, my very 1st SVT!!!

Discussion in 'Amps and Cabs [BG]' started by Aragorn35016, Jun 1, 2018.


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  1. Aragorn35016

    Aragorn35016

    Jul 3, 2004
    Arab, Al.
    1st of all I can’t even begin to tell how blown away that I am that I got this! This really cool older gentleman that was a very seasoned USO tour guy, went on tour as Brenda Lee’s bassist in the early 90’s, and was even TY tabors guitar tech in the mid 90’s (he showed me a cool vid of him at Austin City Limits with Brenda Lee, and a vid of him filling in an acoustic guitar section on stage for Kings X) had this whole setup on CL for 1400!!! He said he bought it from a guy that was a bassist for Elvin Bishop about 3 years ago and just wanted to get rid of it because he didn’t want to move it around anymore. So here it is My 76-79 SVT head and accoording to speaker codes my 1970 8x10 fridge!
    28C80C27-2679-4AE5-96AD-09B6BD23DA58. A3E819CB-11AA-4A9A-8CBA-D5D4DC0ACE2B. 6EAC10D2-DD7C-4232-AE4D-3A62CCC57075.
     
    Last edited: Jun 1, 2018
  2. Aragorn35016

    Aragorn35016

    Jul 3, 2004
    Arab, Al.
    This also marks that after 25 years of playing this is the 1st time I've ever actually plugged into and SVT. I am going to have it serviced in the future. I'm an engineering tech by trade, but I don't have the space resources or equipment at home to do it my self. (Plus i'm used to working on low voltage not kill you electronics in a radar). I'm pretty sure it is going to need a recap, as it does have a little hum, but it may also be the fan injecting noise at it is super loud. The PS caps look like they have been changed at some point, but I'm not sure of anything else. A few of the pots/rocker switches need a shot of de-oxit. Im not sure if the tubes are original or not, and it may be missing a tube shroud on one of the preamp tubes (maybe not supposed to be there, maybe JimmyM. can tell me) 8350E4CC-AA2E-4F9B-80AD-35941F3903DC. 0F402104-2FF3-419C-AAFE-C89A215263AB. 99C68110-D2D3-425F-8759-B9AB62082C42.
     
  3. alaskaleftybass

    alaskaleftybass Will Hanbury, Jr. Supporting Member

    Mar 21, 2012
    Sitka, Alaska
    Nice score! Congratulations! :thumbsup:
     
  4. beans-on-toast

    beans-on-toast Supporting Member

    Aug 7, 2008
    Those power tubes, GE6550A’s are worth their weight in gold. Don’t change them unless necessary.

    Nice amp.
     
    High Camp, bobyoung53, IPA and 11 others like this.
  5. Oddly

    Oddly Unofficial TalkBass Cartographer! Supporting Member

    Jan 17, 2014
    Dublin, Ireland.
    That's gotta be the greatest night-stand ever.
    Congratulations, and I wish you many happy years with it!
     
  6. Aragorn35016

    Aragorn35016

    Jul 3, 2004
    Arab, Al.
    Yeah they look to me inpretty good shape. I’m waiting for the batteries in my fluke to warm up so I can check the bias. Can anyone confirm that those caps date codes are the 47th week of 02 likeI think they are? Also is a tube shield missing on the left or is it not there by default? The bottom 3 tubes on the amp floor don’t have them either.
     
    Pbassmanca likes this.
  7. Aragorn35016

    Aragorn35016

    Jul 3, 2004
    Arab, Al.
    Holy Moly you weren’t kidding :greedy:! Anywhere from 150 to 225 a pair! This purchase has officially became my Best Buy in my history of GAS.
     
  8. Wasnex

    Wasnex

    Dec 25, 2011
    Nice score...especially if those GE 6550s are in good working order. In my experience most SVTs hum a bit, but usually it's hardly noticeable over the fan noise. If you have a multimeter handy, you might check the bias to ensure the output section has balanced current. If the current is not balanced, the amp will produce a dull hum. The bias test points and adjustments are behind the front grill. The grill can be pushed off through the back of the amp...sometimes a small dowel rod can be inserted between the fan blades.

    If the voltage reading at one of the test points (TP) is drastically low (on the order of 33%) this could mean one tube is not conducting. Often this means a fried screen resistor and new tubes; so a trip to the tech is warranted. I wouldn't try to achieve the proper voltage at the TP if one of the tubes is bad, as you would then be running the remaining tubes too hot. GE's are nice, so no reason to burn them up if they still have life in them.

    To clarify...the six tubes are organized in two groups of three. The cathodes of three tubes are tied together and attached to a 1 ohm resistor that is connected to ground. The bias test point measure the voltage drop across the resistor. When all three tubes are conducting and adjusted to spec, the resistor drops 0.72 volts.


    Service Manual attached in case you enjoy reading that sort of thing.
     

    Attached Files:

    ezra1, bobyoung53, GregC and 4 others like this.
  9. Aragorn35016

    Aragorn35016

    Jul 3, 2004
    Arab, Al.

    Thank you for the info! Actually stuck to the incide of back left side of the amp was a small brown folder that contained 1 of each pristine copies of the pre amp and power amp schematics. I pulled the folder/and put them up to keep them pristine.
     
  10. Aragorn35016

    Aragorn35016

    Jul 3, 2004
    Arab, Al.
    So it’s a really big nasty class AB amp?
     
    bobyoung53 likes this.
  11. Pbassmanca

    Pbassmanca In the pocket n' thumpy. So woody, so greasy...

    bobyoung53 likes this.
  12. Aragorn35016

    Aragorn35016

    Jul 3, 2004
    Arab, Al.

    I consider Jimmy the King of Ampeg so I drove him crazy in PMs before I bought it!
     
  13. Wasnex

    Wasnex

    Dec 25, 2011
    I believe the unshielded tube in your preamp is the 6C4. My Blueline does not have a shield on that tube. My Skunkworks doesn't have shields on any of the preamp tubes. Be advised, the shields are telescoping, so don't try to pull them out of the amp. Push them in to expose the sides of the tubes.

    The tubes in the bottom are the PI and drivers...no shields.
     
    bobyoung53 and Pbassmanca like this.
  14. Wasnex

    Wasnex

    Dec 25, 2011
    Yep
     
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  15. Aragorn35016

    Aragorn35016

    Jul 3, 2004
    Arab, Al.
    Thank you I’m glad you told me. I thought they were the old twist lock type that fender amps have.
     
    Pbassmanca likes this.
  16. Aragorn35016

    Aragorn35016

    Jul 3, 2004
    Arab, Al.
    Only other thing that I can think of that I need to do is to maybe put some thin adhesive foam or rubber around the screen on the back, that thing vibrates like mad on certain notes.
     
  17. Basshappi

    Basshappi

    Feb 12, 2007
    Tucson,AZ
    What a score! Congrats!
     
    Pbassmanca and Aragorn35016 like this.
  18. 10cc

    10cc

    Oct 28, 2013
    Other than rotate your knobs clockwise;)
     
    Aragorn35016 likes this.
  19. Aragorn35016

    Aragorn35016

    Jul 3, 2004
    Arab, Al.
    By the by, if anyone knows where I can score a logo for the head, it would be appreciated. Flip tops looks to be completely depleted.
     
    Pbassmanca likes this.
  20. JimmyM

    JimmyM Supporting Member

    Apr 11, 2005
    Apopka, FL
    Endorsing: Ampeg Amps, EMG Pickups
    Yep, I was clued in already. Glad you're enjoying it so far!
     

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