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Help finding a new amp project...with crunch

Discussion in 'Shock Brother's DIY Amps' started by KeepInTune, Dec 4, 2012.

  1. KeepInTune

    KeepInTune TDPRI Member

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    Kindly looking for a little help...

    I built a 5F1 clone last year from Boothill. I really like the smooth tube sound and it was a fun first build. I really have to crank it to get it distorted and dirty, so I use pedals to get the bluesy crunch sound I like (i.e. Boss Blues Driver).

    I'd like to take on another build, but would like something with a channel that will overdrive and give me some good blues crunch. I'd love to do another fender tweed type clone like a 5E3 type of build, but I'm concerned that it doesn't have the overdrive. Is a Master-volume + a Volume the best scenario for this type of amp to get a dirty driving sound, or would it be a second OD channel, like the more modern amps?

    Can anyone suggest an amp that might fit? I'd like an easy build project 5-18 watt range. Thanks!!
     
  2. coldengray

    coldengray Tele-Meister

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    You could make a cheap L-pad based attenuator for your 5F1...takes about 10 mins with a soldering iron. Boothill sells them.
     
  3. Mr Ridesglide

    Mr Ridesglide Tele-Afflicted

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  5. kleuck

    kleuck Tele-Holic

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    Best solution i agree, you can make the gain of the 5F1 higher (higher plate resistor for the first triode, cathode cap if it doesn't already have one) get rid of the nfb (with a switch if you want) and use the attenuator as a master volume.
    I do it all the time :)
    Her is my attenuator :
    [​IMG]

    The simulation is obviously not mandatory, and is an idea from Steve Conner
    Did not draw the switch, but it's easy to figure out.

    (personal use only, do not use on another website please)
     
  6. Jonesamp

    Jonesamp TDPRI Member

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    Hey KeepInTune, if you're looking for a project with "crunch", suggest one of the projects at the AX84 website. http://www.ax84.com/

    Look under Classic Amp Projects or Associate Projects. I've built the High Octane. To hear what they sound like there are tons of videos on Youtube of guys showing off their amps. Search using "AX84" or the name of the circuit. There's also a good forum on the AX84 website for help from guys that have built the amps.

    Steve
     
  7. Telenut62

    Telenut62 Poster Extraordinaire

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  8. t-luxe

    t-luxe Tele-Afflicted

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    By-pass the cathode resistor on V1 with a 25/25 cap, if you haven't already.
    The L-pad or, for a little more $$ , a Weber Mini Mass works great.
    I believe there are instructions for building your own cheap L-pad over on the SuperChamp XD's owner's club forum-search the thread for L-pad, posted by forum member Gnobuddy.
     
  9. kleuck

    kleuck Tele-Holic

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  10. KeepInTune

    KeepInTune TDPRI Member

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    Intrigued about building an L-Pad attenuator box for the 5F1. Looks pretty easy. I've seen that Dave at Boothill uses a 3.3 uf Cap --why might one use a cap? I didn't see one with Gnobuddy's L-pad project. Thoughts?
     
  11. kleuck

    kleuck Tele-Holic

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    Adds brightness when the output is low.
     
  12. KeepInTune

    KeepInTune TDPRI Member

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    A good add you'd recommend? Where is it connected?
     
  13. kleuck

    kleuck Tele-Holic

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    Between input and output lugs.
    It's mandatory for me to get a good usable sound (and a choke too), but this simple trick is not perfect, so most of the times there is two caps and a switch to choose.
    L-pads are not easy to fine tune at very low levels, so I've built some with added resistors :
    [​IMG]
    This one is tiny (cheapo L-Pad from Ebay)
    [​IMG]
    [​IMG]
    But i much prefer the rheostat-based one now.
     
  14. JohnnyCrash

    JohnnyCrash Doctor of Teleocity

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    ^ This.

    I've built the L-Pad thing (just used it to test a 18 watt and a 50 watt build I just finished) and about a dozen 5F1 variations. It's not crunchy. It's flabby bass and dark.

    The AX84 circuits do crunch and low volumes. I built a Hi Octane. It was very crunchy. I've also done a few of their other circuits. Even the Firefly is better at low volume crunch than the 5F1 (not trashing 5F1's - I love building them).
     
  15. Gnobuddy

    Gnobuddy Friend of Leo's

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    I learned about the L-pad from forum member "jeober", all I was doing was passing on what I learned from him. I'd never heard of an L-pad before that. If you search TDPRI for posts by "jeober" you'll find the information he posted about L-pads.

    I do use an L-pad at home. Yes, when you turn down the volume a lot, the sound will seem thinner (less bass) and duller (less treble). This is not because of the L-pad, it's because of the way our ears work. At low volumes our ears are less able to hear deep bass and high treble.

    The best solution I found to this is complicated:
    1) Run the amp's speaker out jack to a Behringer GI-100 Direct Injection box.

    2) Run an 8 ohm, 50 watt dummy load resistor into the GI-100, so the amp sees the proper 8 ohm load.

    3) Run an XLR cable from the DI box to a dBX graphic EQ.

    4) Run the output of the EQ to a small solid-state amp - your home stereo will work, sometimes I use an acoustic guitar amp (Acoustic AG-30).

    Now crank up the guitar amp to get the timbre you want, use the EQ to shape the tone, and adjust the solid-state amps volume to get the speaker volume you want!

    It works well, but is too much for me to bother with most of the time. Usually I'm fine with the timbre I get with just the L-pad.

    I agree with Kleuck about the L-pad being finicky at very low volumes. I came up with a solution similar to his, I have some fixed resistors that cut the amps power from 15 watts to about 1 watt before it goes into the L-pad. With that added, you can get the L-pad away from its minimum setting, and it will be more linear and easier to adjust. It will also run cooler.

    -Gnobuddy
     
  16. kleuck

    kleuck Tele-Holic

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    Adding a choke (1mH) and a treble-bleed to a L-Pad makes it very usable at low volume (along with a pre-divider).
     
  17. Racing

    Racing Tele-Meister

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    I don´t get what it is that makes people/guitarist/builders shy away from using multiple stage preamps to accomplish what´s asked here.?

    Yeeees...per definition a circuit based on 4 gainstages or more is a highgain one. However that is not the same as that the sound out of it has to be.
    I do it all the time. Use mutliple stage preamps to build TONE. Screw the distortion bit of it.
    By altering cathode resistors in particular you can cater to and tailor the sound you´re after to basicaly any needs.
    The "run the powerstage to the verge of meltdown" feels soooooo 1990....no offense.

    A well setup 4 stager for instance WILL rock you wont believe when done right,and noooooo...it does NOT have to sound like a damn Valveking on crack.
    You use the gainstages to flavour. Not build amplitude.
     
  18. kleuck

    kleuck Tele-Holic

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    Not the same response and sound as a cranked power stage, matter of taste, but i prefer to rely on power distortions (mainly) either with SE and PP.
    And, cost-wise, a good attenuator is not very expensive if you build it yourself.
    The rheostat one i posted post #4 is really a beast imho, and cheap (the rheostat dissipates only 1/4 of the power, does not need to be a big expensive one)
     
  19. Gnobuddy

    Gnobuddy Friend of Leo's

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    1 mH has a corner frequency of 1.274 kHz with an 8 ohm load and won't do much below that frequency. 1.274 kHz is near the highest notes you can get out of an electric guitar. :confused:

    I must be missing something, can you please explain how are you using the 1 mH inductor in your circuit?

    -Gnobuddy
     
  20. kleuck

    kleuck Tele-Holic

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    The choke is here to simulate the inductance of the speaker, not to make a filter.
    At first i used more realistic values (330-500mH) but 1mH sounds better.
    The Capacitor + series resistance is a treble bleed, which efficiency is limited by the resistor : i don't like to add switch when i can avoid to.
    As it is, it's pretty consistent (by ear) on the whole travel of the pot (i'm talking of the schematic post #4 with a rheostat, works well with a L-pad too, but i did not try more than 500 mH with these, as i switched to rheostats)
     
  21. JohnnyCrash

    JohnnyCrash Doctor of Teleocity

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    1990s? Running a 5F1's power section to the verge of meltdown doesn't sound 1990s, it sounds like Chuck Berry circa 1958.

    Same with Trainwreck circuit amps - they sound mean, but not 90s. Same with 18w Marshall 1974x circuits. And an 18w Marshall only has one gainstage.



    That said, I agree with you. I get tired of some old fellas trashing preamp distortion with multiple gainstages. I like JCM800s (and I like their pre-PI Master Volumes. Sure, I ALSO like PPIMV, attenuators, OD/Dist pedals, and other types of crunch at manageable volumes).

    In this case though, a 5F1 might not be the best platform for 4 gainstages.

    An AX84.com Hi Octane is 5 watts AND has several gainstages (essentially a JCM800 preamp with a 5w power section) - you can get both preamp and/or power amp distortion without bleeding ears :)
     
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