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Blonde Fender Bassman - Mismatched Impedance

Discussion in 'Glowing Bottle Tube Amp Forum' started by DannyStereo, Apr 10, 2018.

  1. Wally

    Wally Telefied Ad Free Member

    Mar 17, 2003
    Lubbock, TX
    Danny Stereo, is there a date stamp hiding in the shadows there on that the chart. I can’t see one, but it is dark to that one side there...
    The power transformer has a date code for the 42nd week of 1961.ir is possible but perhaps not likely that the amp was built in 1961. The tube chart date would be definitive if it were there. One could check all date codes on pots, chassis, etc...but you may never know the year or month of actual manufacture for the amp without The tube chart date. The serial number can usually tell us when the amp was built unless the number falls on the cusp of a year change.
    You can check your serial number against this data base....

    http://www.ggjaguar.com/fendamp5.htm

    I am not sure that I understand why someone would use a dummy plug in the shorting (main) speaker jack and the. Run a speaker off of the extension jack???? Of course, many people do strange things...but the Fender OT’s are not multitap and running one of them the way described simply uses a dummie 0lug and two jacks to achieve what could be achieved by plugging the one speaker can directly into the main jack. One of these amps should never be run with nothing plugged into the shorting/main jack.
     

  2. Dacious

    Dacious Poster Extraordinaire

    Mar 16, 2003
    Godzone
    I was more responding to a statement which seemed to imply it didn't matter which jack you plugged into, when it does if one's a shorting jack with nothing plugged in. I'm sure that's not what the poster intended, but it sort of reads that way.
     
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  3. Wally

    Wally Telefied Ad Free Member

    Mar 17, 2003
    Lubbock, TX
    Good day! Agreed...... I mainly was responding to the statement about EvH running on the extension speaker jack.
    There are ways to set up a multitap OT output so that the jacks switch for the desired impedance. Only in such a case would one want to use a dummy plug in a ‘main’ shorting jack, or one can have a switch to select impedance, or one can have multiple jacks without having a shorting jack as in some Mesa amps. They have an 8 ohm jack and two 4 ohm outputs. In say a MK 1x12 combo with an 8 ohm speaker, the speaker is run on the 8 ohm jack. If one had an 8 ohm extension speaker and wanted run it in addition to the incab speaker, the incab speaker lead has to be to placed into one of the 4ohm output jacks with the ext spkr in the other 4 ohm jack. Various ways to achieve a goal...various goals, too. I prefer matched loads. Some find things they like with ‘safe’ mismatches.
     

  4. Wyatt

    Wyatt Tele-Holic

    936
    Nov 3, 2004
    That's not what I meant to imply, BUT I did omit the very important...ALWAYS plug into the Main Speaker jack first.
     
    Last edited: Apr 16, 2018
    Wally likes this.

  5. Dacious

    Dacious Poster Extraordinaire

    Mar 16, 2003
    Godzone
    I read an interview with the guy who's credited with teching his amps before he did the endorsement deal for the PV 5150s - Eddie used to spin people out with claims about this mod, or that mod...... Apparently his Marshalls were all stock standard, including speakers, and dimed on everything. The guy kept good tubes and biased properly, that's it. All the tone, and the licks, were in Eddie's hands, apparently.

    The tech said people came to him and said 'make my amp sound like Eddie's, and he'd say put everything on 11....' they wouldn't believe him and paid him for all sorts of mods like extra gains stages, preamp voicings. Eddie started the rumour in an interview about the variac pulling down mains voltage on a Fender amp for recording, but liked the sound of this particular Fender he had, all turned up. Bone stock through a stock speaker cabinet.

    This dude (can't find the article now of course) said Eddie had this brown Fender head which someone else identified as a Bandmaster, and always plugged his speaker in to the easiest to find jack reaching around the back, which turned out to be the extension jack, leaving the shorting jack earthed. He recorded it like that, years later someone noticed - it'd been like that for ages, which means his not-live tone was accidental.
     

  6. Wally

    Wally Telefied Ad Free Member

    Mar 17, 2003
    Lubbock, TX
    Maybe the shorting jack in that particular Fender amp head was open or had been changed???? There is not much output when running only out of an extension jack with the shorting jack for the main output operating as it should...because it is shorting the OT signal to ground. I guess you just had to be there to understand what goes on. On those old big Marshall one can plug into any of the four jacks since there is no shorting jack used in the circuit.
     

  7. radiocaster

    radiocaster Friend of Leo's

    Aug 18, 2015
    europe
    The one he bought has 4 stages in the bass channel though...
     

  8. Jeru

    Jeru Tele-Holic

    560
    Nov 17, 2006
    Chicago
    Watch uncle Doug’s video on YouTube re output transformers. GREAT info If you want to understand the question rather than just get the answer.
     

  9. Wyatt

    Wyatt Tele-Holic

    936
    Nov 3, 2004
    Three gain stages plus a cathode follower. Cathode-followers are unity-gain buffers, they don't increase gain (but they can clip signal). The Bass channel has more OD on tap, but players are pretty mixed on whether they like the voicing for guitar.
     
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  10. Wally

    Wally Telefied Ad Free Member

    Mar 17, 2003
    Lubbock, TX
    I never played guitar through a Bass Channel in a stock Fender Bassman piggyback that I thought yielded a good guitar sound by itself.
     

  11. Teleguy61

    Teleguy61 Friend of Leo's

    Correct load is always best, but those amps are wicked tough, and have a very heavy output transformer--a nice big Schumacher.
    Going up in impedance load is not too big a worry.
    It is one of Fender's greatest--enjoy!
     

  12. DannyStereo

    DannyStereo Poster Extraordinaire

    Aug 13, 2014
    Kelso, Washington
    I actually REALLY dig the Normal Channel. Soooooo thick and downright NASTY (in the good sense). Just rock n roll.
     

  13. radiocaster

    radiocaster Friend of Leo's

    Aug 18, 2015
    europe
    You're right. For some reason I thought it was a plate follower, but apparently that's only on the normal channel.
     

  14. DannyStereo

    DannyStereo Poster Extraordinaire

    Aug 13, 2014
    Kelso, Washington
    In case anyone is wondering, been playing the Bassman through my Z 2x10 cab... Glorious.
     
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