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5f1 Champ line out?

Discussion in 'Amp Tech Center' started by daley.bc, Aug 12, 2018.

  1. daley.bc

    daley.bc TDPRI Member

    32
    Oct 8, 2016
    Australia
    Hi all. I have a 5f1 champ clone head that I built and I'm wondering how to install a line out with a few possible options.
    1: line out with speaker still connected
    2:line out with a dummy load so I can just plug the head in direct
    3:line out just from the preamp
    I've found a few other threads about this in various places but none that answer these specific quiestions.

    Thanks :)
     
    LarryBudMelman likes this.

  2. Jakeboy

    Jakeboy Tele-Afflicted

    Jul 26, 2008
    Sedalia, MO
    Ask Jim at Lil Dawg. His line out come right off the speaker taps. Easy-Peasy
     
    nojazzhere likes this.

  3. MickM

    MickM Friend of Leo's Silver Supporter

    Good idea. My 1st Li'l Dawg is a 5f1 oversized cab combo with an external speaker tap and one for a line out. Unfortunately I've never had it apart to see how that stuff is wired.
     

  4. FenderLover

    FenderLover Friend of Leo's

    Jun 11, 2009
    Minnesota
    Off of the speaker is the best, to include the back EMF effects of the speaker. Also works with a dummy load plugged in as a second-best. Spend a couple extra dollars for a 1:1 isolation transformer, but may not be necessary for your application. Go to Weber for their transformer, it's about $4.

    In my opinion, this is the single best mod for any amp, especially a Champ.
     

  5. daley.bc

    daley.bc TDPRI Member

    32
    Oct 8, 2016
    Australia
    Hmmm seems that the proper dummy load "reactive" boxes are bloody expensive. What about just getting a line out from the preamp stage?
     

  6. D'tar

    D'tar Tele-Afflicted

    Jan 11, 2013
    WNY
    nojazzhere likes this.

  7. FenderLover

    FenderLover Friend of Leo's

    Jun 11, 2009
    Minnesota
    A line out from the preamp doesn't give you any of the reactive quality of the load (speaker) but would be done the same way shown above by D'Tar before the phase inverter. It may also be made more versatile by adding a pot to set a usable output range, whether used at the output or preamp position.
     

  8. nojazzhere

    nojazzhere Friend of Leo's

    Age:
    66
    Feb 3, 2017
    Foat Wuth, Texas
    I believe this is what I've done several times, sourced from Gerald Weber's Tube Amp Book. (in the Tweed Deluxe mods section) I've even built a couple in little metal project boxes, so I can use as a line out for ANY amp.
     

  9. Wally

    Wally Telefied Ad Free Member

    Mar 17, 2003
    Lubbock, TX
    A signal from the preamp is a preamp out...not a line out, ime and imho. It is a preamp out. The line out taps the speaker leads and gives one a signal that contains all of the amp’s circuit’s signal. There are two resistors, a jack and a few inches of wire needed.
     

  10. daley.bc

    daley.bc TDPRI Member

    32
    Oct 8, 2016
    Australia
    So if I was to take a preamp out it would be from right after V1B coupling cap?
    Do i need to worry about V1B cathode 1.5k resistor or anything else after that coupling cap?
     

    Attached Files:


  11. daley.bc

    daley.bc TDPRI Member

    32
    Oct 8, 2016
    Australia

  12. Wally

    Wally Telefied Ad Free Member

    Mar 17, 2003
    Lubbock, TX
    Daley, if you want to take the signal of the entire circuit...a line out....you want to tap off of the speaker leads. I prefer this true line out to a preamp out because it is...well....it is the entire signal including what goes on in the output transformer. There is a big equation involving the power tube, the OT and the speaker that has a lot to do with what happens in that Champ. If you want a ‘bigger’ Champ, you want the signal from the OT, imho.
    Rob...rob rob...probably has a preamp out described in his site somewhere.
    If I were to build a preamp out, I would build an effects loop. A preamp out is half of that loop with the return to the power amp being the other half. I would use that for insertion of effects in the post-preamp area of the circuit. I would then also build the line out for the purposes that you are seeking.
     

  13. Alamo

    Alamo Doctor of Teleocity Silver Supporter

    Nov 15, 2006
    Berlin
    For that I have a Hughes & Kettner Red Box. the good thing about it is I can use it with different amps.
    and it's isolated.

    1-DSCN2318.JPG
     
    FenderLover likes this.

  14. daley.bc

    daley.bc TDPRI Member

    32
    Oct 8, 2016
    Australia
    Ok cool I'll try this. Why are there 3 jacks though? Wouldn't it just be the speaker out that already exists and then one extra jack for the line out?
    Also, when using this mod ,does the speaker that's already connected still work or is it bypassed?
     

  15. Wally

    Wally Telefied Ad Free Member

    Mar 17, 2003
    Lubbock, TX
    Daley.bc, Rob is maintaining the ext spkr jack while providing for the line out through a new jack one could use the ext spur jack. The main speaker jack and the speaker attached through it are still in-circuit and functional.
     
    D'tar likes this.

  16. D'tar

    D'tar Tele-Afflicted

    Jan 11, 2013
    WNY
    What Wally said. I'll just say that you MUST leave the speaker connected or use a dummy load if you don't want sound from the speaker.
     
    Wally likes this.

  17. wanderin kind

    wanderin kind Tele-Meister

    Age:
    63
    257
    Apr 24, 2018
    Olympia WA
    what are you going to do with the line out?

    coming off the speaker might be fine for home recording, i would not use it for live playing, you might get away with it, but usually the sound guy is gonna want a balanced output, which usually means a small transformer in there somewhere, he might slap a DI box on your spk tap and be happy, , i guess you could lift the ground off your speaker jack by insulating it with fiber washers, this may or may not cause more noise, Music Man amps had insulated spk jacks on some of their models for reasons unknown to me,

    the output from the speaker is kind of dirty, lots of pwr supply ripple and possibly heater hum from the power tubes, especially with a single ended amp although i had a silverface champ in the shop the other day that was very quiet, even with the grounded heater circuit go figure, most champs have that single ended cathode bias hum thing going on,

    you can tap off the second stage, Ampeg had preamp outs on their older V4 amps IIRC, might be less noise but you are still unbalanced,

    good ol Sennheiser hanging off the handle is hard to beat,
     
    Last edited: Aug 19, 2018
    Alamo likes this.

  18. robrob

    robrob Poster Extraordinaire Ad Free Member

    Dec 29, 2012
    United States

  19. FenderLover

    FenderLover Friend of Leo's

    Jun 11, 2009
    Minnesota
    'Line' refers to signal level. Whether at the preamp or the output, the signal is padded down to line level to be compatible with other equipment and are both line outputs.

    Notice the Red Box II has Speaker and Line inputs. The Speaker is from the output and the Line is from the preamp (or other) line level. The output is presumably +4dBU.

    'Slave output' is another term that is generally at the speaker output but not always, depending on the amp. It is also at line level, and is a line output.

    At least we are all being clear on where the signal is taken, and why, which is good because the names have become a bit universal.
     
    Last edited: Aug 19, 2018

  20. Wally

    Wally Telefied Ad Free Member

    Mar 17, 2003
    Lubbock, TX
    Fender Lover, I have always taken ‘slave out’ to be a preamp feed to another power amp. I differentiate the line out to be a signal taken from the speaker lead circuit. This is how I learned to differentiate between the two almost three decades ago, and I will continue to view them to be different as to their source. I understand that the two signals are at a level that is compatible with the input of another device, and I also think that the similarity of the signal level demands the differentiation of terminology so that we all can agree on the basic difference between the signals, one being a preamp signal and one being a signal brought off of the complete circuit.
    Among others, Marshall offered an amplifier over forty years ago that provided for a slave situation. The primary Amplifier was a 50 watt amp that provided a slave out...form the preamp....that could send signal to as many as 9 speaker cabs that each had its own power amp, which was identical to the one in the main amp. Voila...500 watts of power amps amplifying the same preamp signal. I owned a big Kustom amp that had the same type of slave arrangement.
    That said, I understand that there is no way that terminology can be maintained once the differences in the basic meaning of the two terms are jumbled up on the ‘net.
     
    FenderLover likes this.

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