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Some Discussion on Amp EQs

Discussion in 'Amps and Cabs [BG]' started by dunwichamps, Jan 21, 2013.


  1. dunwichamps

    dunwichamps Commercial User

    Jul 23, 2012
    Owner: Dunwich Amps
    bump this up for folks knowledge sake
     
  2. Korladis

    Korladis Inactive

    Do you know what the "contour" control does? How about the "bass boost" on the 200S/2000S and the "mid boost" on the 1200S? How do those work?

    Sorry, I know these questions are probably annoyingly specific.
     
  3. dunwichamps

    dunwichamps Commercial User

    Jul 23, 2012
    Owner: Dunwich Amps
    Bass Boost just switches in another a cap in the coupling of the first stage to the volume pot resulting in lowering the HPF that is formed. Thus, cutting less bass.

    Contour on the old 1200s tube amp was just the Mids control of a FMV. I cant quit tell what is the Mid Boost switch from the scheme but there is a 3PDT switch listed which adds varying gain to parts of the amp which would have an apparent boost to upper mids and high end.
     
  4. JimmyM

    JimmyM

    Apr 11, 2005
    Apopka, FL
    Endorsing: Ampeg Amps, EMG Pickups
    Glad you bumped this thread, Mr. Dunwich. It's legendary.
     
  5. dunwichamps

    dunwichamps Commercial User

    Jul 23, 2012
    Owner: Dunwich Amps
    thanks bro! I hope it has helped some people. Others feel free to contribute
     
  6. Korladis

    Korladis Inactive

    One of the best threads in the Amps subforum, and probably on talkbass.
     
  7. Azure Skies

    Azure Skies Commercial User

    Mar 21, 2012
    Toronto
    Businessman and EE Importer/Exporter Broughton Audio
    I am curious how the mid range circuit affects the output impedance. Is it possible to drive a signal to a mixer from the output? Would it need a transformer, like the Jensen tube line out? Where exactly would the output be taken, between R38 and R40?
     
  8. dunwichamps

    dunwichamps Commercial User

    Jul 23, 2012
    Owner: Dunwich Amps
    I would not drive very low impedance signals off this but if you could drive into a 100k load that would be good. If you needed <10k impedance then a transformer might be better.

    Someone has mentioned that the Ampeg bax treble sweep is down

    [​IMG]
     
  9. dunwichamps

    dunwichamps Commercial User

    Jul 23, 2012
    Owner: Dunwich Amps
    bumping this up for the uninitiated!
     
  10. eddododo

    eddododo Supporting Member

    Apr 7, 2010
    This is a 'bookmarked on every device' thread for me, thanks alot
     
  11. Very informative and useful. Thanks everyone. Read the whole thread again just now. Some was over my head, but plenty wasn't. I have a V4B and appreciate the info that applies. A lot of TB users, like I, use the SVT-CL. Is it safe to generalize the EQ as working the same way but with the addition of two center frequencies in the mid selector?
     
  12. dunwichamps

    dunwichamps Commercial User

    Jul 23, 2012
    Owner: Dunwich Amps
    Possibly but I could need to see a schematic to confirm
     
  13. Jeff Scott

    Jeff Scott Rickenbacker guru..........

    Apr 11, 2006
    I just found this fascinating thread this evening. Thanks so much much for all of this, Dunwich! :cool:
     
  14. dunwichamps

    dunwichamps Commercial User

    Jul 23, 2012
    Owner: Dunwich Amps
    no problemo, glad you found it useful!
     
  15. DethByDoom

    DethByDoom

    Sep 23, 2012
    Houston,Tx
    Did you cover the orange bass terror's eq? I thought I remembered Laz saying you schooled him on it... Might have been in the s/d thread...
     
  16. dunwichamps

    dunwichamps Commercial User

    Jul 23, 2012
    Owner: Dunwich Amps
    without a scheme I would not know but if its passive FMV then you can find it in here
     
  17. teemuk

    teemuk

    Mar 1, 2011
    Interesting thread. Thumbs up!
     
  18. ejsagun

    ejsagun

    Jan 20, 2003
    @dunwichamps...


    the mid boost pedal you posted, Is it similar to the SVT mid circuit?
     
  19. dunwichamps

    dunwichamps Commercial User

    Jul 23, 2012
    Owner: Dunwich Amps
    its much simpler, just an series LC bypass on a FET gain stage, its a mid boost only (no mid cut)
     
  20. jazzercountry

    jazzercountry

    Apr 12, 2000
    Oklahoma
    Endorsing Artist: Lakland Basses
    It might be completely unrelated, but since the Aguilar DB680 is long discontinued now I was curious as to whether it fell into one of these categories (minus the 2 bands of parametric, obviously).

    Great informative thread!
     
  21. Primary

    Primary TB Assistant

    Here are some related products that TB members are talking about. Clicking on a product will take you to TB’s partner, Primary, where you can find links to TB discussions about these products.

     
    Apr 13, 2021

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