Tweed Circuit Feedback/Bloom .. or lack thereof

Discussion in 'Other Amps' started by JS Tele, Dec 13, 2019.

  1. JS Tele

    JS Tele New Member

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    I'm having trouble getting notes and/or chords to bloom when held (even at max volume).

    My current rig:

    Lil Dawg Harvard (5f10) combo

    Combo has a 12" Fane Ascension A60 speaker (8 ohm).

    Extension Cab: Peter Mather matching tweed cab with 12" EVM 12L (8 ohm).

    The combo and extension cab go into a Dr Z Air Brake (to keep neighbors friendly).

    From the amp's build sheet:

    JJ 5Y3GT rectifier tube

    Mercury Magnetics transformer set upgrade (FTWHARV-P, FTWHARV-O)

    Sprague Atoms filter & bypass cap upgrade

    SoZo Blue Molded coupling cap upgrade


    BTW, I define bloom as holding a note or chord and having feedback/bloom kick in (usually the 5th above the octave of the fundamental, but this varies according to pickup position relative to speaker cone).

    I've tried 3 different overdrives to push the amp a bit more hoping that would do it, but no luck: Hudson Sidecar, Zendrive and Black Magic by Crazy Audio Circuits. All excellent overdrives, none make much of a difference.

    I do have the volume maxed out on the amp and have held the pickups right up to the cone on the Fane.

    I play an assortment of Teles & Strats (Tom Anderson, Fender).

    Perhaps someone who knows this circuit can shed some light on this? Thanks.
     
    Last edited: Dec 13, 2019
  2. South Park

    South Park Well-Known Member

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    You have to much signal lower the pick ups
     
  3. mickeydg5

    mickeydg5 Well-Known Member VIP Member

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    Your volume control is maxed but how is the Air Brake set?
    That is kind of counterproductive for producing harmonic feedback.
     
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  4. JS Tele

    JS Tele New Member

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    mickeydg5, see attached image for Air Brake settings AB.jpeg
     
  5. mickeydg5

    mickeydg5 Well-Known Member VIP Member

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    So you have it on Bedroom level at about 40% up which is probably cutting it down 16dBm or so.
    A 10 watt amplifier maxed on an attenuator set like that is probably putting out less than a half watt.
    You aint really in feedback territory.
    And maybe your guitars/pickups are not helping.
     
  6. anitoli

    anitoli Well-Known Member

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    Feedback requires VOLUME. The idea is the sound pressure is great enough that it can vibrate the strings thereby creating an infinite sustain as the signal is back fed into the amp, amplified and vibrating the strings continuously.
     
  7. ampmadscientist

    ampmadscientist Well-Known Member

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    Start the reactor... Free Mars!
    You are talking about sustain.
    It depends on the amp, the guitar, and the phase relationship.
    Some guitars have no sustain at all. So what guitar are you using?
    Did you think that all those fancy upgrades would make the amp sustain?

    But yes 5F10 is a very low gain amplifier and I would not expect much sustain from that circuit.
     
  8. JS Tele

    JS Tele New Member

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    I usually use either a Tom Anderson Strat or TA Rosewood Tele (both single coils). The Tele does have a VA Booster which I usually have "on". From the TA site: " ... with the flick of a switch, we rewind your pickups for a little more saturation and oomph while still retaining the same overall character".

    I've started to suspect that that circuit (5F10) simply can't get there :nono:
     
    Last edited: Dec 14, 2019
  9. mickeydg5

    mickeydg5 Well-Known Member VIP Member

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    He is talking about amplifier/cabinet feedback, no guitar sustain, although good sustain helps with the feedback effect.

    It is not the amplifier design. 10+ watts from an amplifier and efficient cabinet/speakers is more than enough to produce feedback if standing up front.

    The damn Air Brake is the problem.
     
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  10. ampmadscientist

    ampmadscientist Well-Known Member

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    Start the reactor... Free Mars!
    I think you are short about 3 preamp stages....
     
  11. wakjob

    wakjob Well-Known Member

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    Bingo...attenuators aren't always the answer...
    especially with those old Fender circuits.
     
  12. ampmadscientist

    ampmadscientist Well-Known Member

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    Start the reactor... Free Mars!
    Actually it is the amplifier design.
    It takes 2-3 parts to make the amp sustain like crazy.
    But if I told you how to do this, Mesa Boogie would copy it (and so would everybody else).

    And it does definitely have to do with the guitar, especially the wood that the guitar is made from.

    Then I wouldn't have as much fun teasing you guys about it, my fun would be ruined.
    It's much more entertaining to taunt you, then to tell you how to do it. :lol:
     
  13. mickeydg5

    mickeydg5 Well-Known Member VIP Member

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    The design of this amplifier plays a part in that it is not high gain heavy saturation preamp but that is not the topic here. He is talkng about getting any feedback from the guitar.

    His main problem or issue is the attenuator.

    Now you admit it could also be the guitar but @JS Tele has tried more than one. They cannot all be bad sounding low quality guitars from Tom Anderson and Fender.

    He has also tried pushing the front with pedals which should do a lot but it aint going to do anything for guitar feedback without pure volume and less attenuator.

    Taunt us??? Your efforts are futile and vain.
     
    Last edited: Dec 15, 2019
  14. mickeydg5

    mickeydg5 Well-Known Member VIP Member

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    For once pull the Air Brake out of the equation, slap the heaviest overdrive in front of the amplifier and then maximize the volume.
    Do you get guitar feedback now?

    If not then I call bullshit on this thread. :agreed:
     
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  15. mickeydg5

    mickeydg5 Well-Known Member VIP Member

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    Oh by the way if you want notes and chords to bloom from guitar feeback you have to get a good bit of it and the biggest thing is to know how to control it. I am believing neither is the case here.
     
    Last edited: Dec 15, 2019
  16. JS Tele

    JS Tele New Member

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    In times like this, I wish I had my Mesa MKIIB combo w/ EVM12L back. Used it when I used to gig a lot back in NYC. When set right, just letting go of the strings for a second would instantly produce the feedback/bloom ....
     
  17. mickeydg5

    mickeydg5 Well-Known Member VIP Member

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    So was that at 60W or 100W and how were the controls set?
     
  18. JS Tele

    JS Tele New Member

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    I had the 100/60w version with all the options .... been so long man, can't remember much re: settings ... but I do remember it was kinda clean with just a touch of crunch. In most rooms, the master was at 2 or 3 in 60 watt mode with the eq set to a "V" and I do remember the "pull boost" engaged. An Echoplex and a PCM-42 and the tone was just perfect (for me).
    Used to have quite a few guitar players comment on it at gigs.

    These days I couldn't even think about lifting that amp (back issues) ...
     
  19. mickeydg5

    mickeydg5 Well-Known Member VIP Member

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    Even at 2 or 3 with that MKIIB amplifier you were still pushing 3-5 watts.
    There is a big difference between that and a third of a watt.
     
  20. tschrama

    tschrama Well-Known Member

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    place your speaker at waist height. Use plenty of volume.
     

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