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Bassman 100 too 'clean'

Discussion in 'Amps and Cabs [BG]' started by cman808, Jan 17, 2017.


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  1. cman808

    cman808

    Mar 5, 2014
    I recently acquired a mid 70s silverface Fender Bassman 100 -- for me, it sounds too clean for my liking, and I can't get it to break up at all (note: I'm playing either a 70s hagstrom or jazz bass, and using a 410 cab). Are there any changes I can make (ie: changing tubes, phase inverter, etc..) to change this, or am I stuck with this clean tone? Nothing wrong with clean tone, but I was hoping for a sound similar to a V4B and the like
     
  2. BogeyBass

    BogeyBass

    Sep 14, 2010
    If the levels your playing at are low enough to still get clean tone, then you would want a 50watt amp.

    And yes beyond popular praise on talk bass that 100watts isn't enough power.

    It's not true 6L6 beam plate tubes stay very very clean up until the very end and then they start to grind.

    So without going into specifics about your playing situation. If your playing at low volumes with a 410 in your bedroom that amp is gonna stay crispy clean.

    If you have to crank it loud to cover a loud drummer that things gonna breakup rather nicely.
     
    Meghans Dad likes this.
  3. BusyFingers

    BusyFingers

    Nov 26, 2016
    Those were made to be clean machines, but you may be able to coax some preamp overdrive out of it by getting some higher gain 12ax7 preamp tubes. An overdrive in front of hot tubes can sound very musical, too.

    This might do the trick. You will have to do some research to figure out which preamp tube is for which channel. You can find out on your own just by swapping one and seeing if it affects the channel your plugged into.

    www.thetubestore.com - Shuguang 12AX7-A Audio Tubes
     
  4. BusyFingers

    BusyFingers

    Nov 26, 2016
    It's also possible to pull two power tubes in some amps, not necessarily all amps. That will lower the overall volume and headroom of the circuit. It may change the impedence, however, and should be researched before attempted.
     
    physics and Dave Hawthorne like this.
  5. BusyFingers

    BusyFingers

    Nov 26, 2016
    One of the things about those old silver face bassman amps is they were super bright. An amp tech may be able to tame the treble frequencies with some simple changes to components, if you wanted to. They could also advise you related to pulling power tubes.

    Swapping preamp tubes isn't hard, just shut it down when you're swapping them and be careful with the pins upon plugging them in.
     
  6. hennessybass

    hennessybass

    Oct 11, 2008
    Houston, TX
    Great example of how "watts" doesn't really mean much, and amp design means everything.

    I have a '77 Bassman 100, and have done a LOT of gigs with it. The fender does stay pretty clean, but has a great breakup when you push it, and really dig in. That's why I like it. It compresses and puts a nice hair on your notes. Very touch sensitive. ... all IMO, and IME.

    If you are looking for more of a "grind", the Ampeg V4b might be more up your ally. They tend to break up early... both 100watts, but different design philosophies.

    I would recommend the following...
    Use a dirt pedal - which kind of defeats the purpose... if you don't want to change the flavor with a dirt pedal, think about a clean boost. Hitting the pre amp hard will help. Crank your gain to 10, and hit the master section hard, using the master to adjust volume.

    You might also try a jumper cable. Bass into ch 1, input 1... jumper cable from Ch 1, input 2 -> ch 2, input 1. This will give you a second gain stage. Crank the vol on ch 1, and you will be hitting ch 2 hard. Crank ch 2, and you will be hitting the master double hard. Same idea as a clean boost. This gives you some additional EQ options as well.

    I love my fender amp. I say give it some time and get to know it!
     
    SactoBass, Tbone76 and S.fasciani like this.
  7. BogeyBass

    BogeyBass

    Sep 14, 2010
    You can pull tubes. It not a matter of if the impedance will change. It will.

    The bassman already uses 12ax7 tubes though. So no more gain to be found.

    But yes channel jumping will give you a lot of gain.... A lot. The bassman 100 probably my favorite head for distortion as described above. at full volume or almost full volume it is a very lovely riding on the edge touch sensitive distortion. Now channel jumping and getting buzz saw preamp distortion little different a lot different. And trying not to sound negative but 12ax7 distortion is pretty annoying in my opinion.. Tube or not its nothing like output tubes especially beam plate tubes riding on edge
     
    Last edited: Jan 18, 2017
  8. cman808

    cman808

    Mar 5, 2014
    Thanks for the info and help. Sounds like the amp is supposed to be clean, but I literally get no breakup with the volume AND the master volume at 10. I've tried swapping the 12AT7 preamp with a 12AX7, but that didn't help. Note: the amp calls for 4ohm impedance and I'm running it through an 8ohm 410 cab. Could this make a difference? Also, does anyone know about the voltage control setting on these amps?
     
  9. cman808

    cman808

    Mar 5, 2014
  10. primusfan1989

    primusfan1989

    Jan 17, 2005
    new jersey
    Good news is you're not stuck with that clean tone, however you're gonna need to either
    A) Put a boost or OD in front of the amp (I have a 78 Fender studio bass that i have a similar issue with, so when i need a bit more hair on my tone, I use an old Marshall Guvnor on minimum gain setting , eq to taste and the output level cranked to slam the front end of the amp
    B) Find a distortion pedal that will give you the tone you want, perhaps the VT-bass if the ampeg thing is what you desire
    C) Find a good amp tech and see if he could modify the amp (Im sure any good amp tech could get some more hair out of that bassman)
     
    cman808 likes this.
  11. bigtone23

    bigtone23

    Dec 10, 2014
    Denver, CO
    I have owned a few Bassmen over the years-from blonde to silver. Fender kept making them cleaner with each iteration, so you need to take some circuitry back in time to get some hair. My Bassman Ten can get a little grit with the channel jumping mentioned earlier in addition to a cool mod to remove the negative feedback-a "Soul Control".

    This is really easily done and reversible if the master volume on your head is not really necessary. Replace the master with a fixed resistor of the same value (so it essentially on 10) and replace the pot with a 5 or 10K linear wiper wired to the NFB resistor and across the output jack. Mine was tweaked a touch so when the knob is set around 1-2, it will sound like the stock Fender NFB, as you turn it up the negative feedback gets removed and at 10, it's gone. The amp gets a little louder, a little looser, a little more hairy at the expense of being a little noisier. Worth it.
    If you use the master volume, another option is to get your amp up to modern code, remove the death cap and use the ground switch on the back to switch between stock and a full removal of NFB for the most variance. The resistor can be tweaked to your liking.

    Otherwise, I add grit to my modern heads with a Boss BB1X. With the bass and treble controls set to 4 and adding a touch of grit and blended to taste, it's pretty transparent.
     
    Last edited: Jan 18, 2017
  12. BusyFingers

    BusyFingers

    Nov 26, 2016
    This is not true. 12ax7 tubes can have a range of how gainy they are. They also differ in the EQ range they accentuate, which can have an impact upon their ability to overdrive. That's why the link I shared noted that particular 12ax7 is known for it's gain.
     
    Last edited: Jan 18, 2017
    Plucky The Bassist likes this.
  13. two fingers

    two fingers Opinionated blowhard. But not mad about it. Gold Supporting Member

    Feb 7, 2005
    Eastern NC USA
    Either a boost pedal in front of it or Daisy chain the channels.

    Plug your bass into input 1 of the left channel. Then run a short SIGNAL (not speaker) cable from input 2 of the left channel to input 1 of the right channel. That will in essence stack their gain stages. I do this with an old Fender PA100 that shares some aspects of the Bassman circuit. You will need to fiddle with the tone controls because they act off of each other. If you adjust the treble knob on the left channel it will change things throughout the circuit down the line. So getting "your tone" will take some time. But once you dual it in you should be able to get a little dirt out of it.
     
    cman808 likes this.
  14. hennessybass

    hennessybass

    Oct 11, 2008
    Houston, TX
    That is a mod I've not seen before.

    If you are playing into an 8ohm cab, they you are essentially lowering the "watts" of your amp. You are not getting full power, which should contribute to an earlier breakup. I think that is fine with a fender amp,,, although over time, it may wear on the amp,,, but I think it's fine. You are essentially getting somewhere around 1/2 watts by doing that.

    IME, cranking the preamp all the way up does not produce the "buzz saw" type breakup. They are designed to stay clean, so by cranking the pre, you are hitting the power section hard, causing it to compress and distort. You are just not going to get buzz saw tones, or fuzz tones, or grind tones, or super heavy distortion out of this amp. IME, this amp does overdrive, as opposed to distortion, and Fuzz.

    If you are using an 8 ohm cab,, and have tried cranking the pre and master up to 10, and still no dirt,, then I have to feel like there is something else going on... and that something may be that you are looking for a different flavor of OD, or more likely distortion than this amp can do.

    What context are you playing the amp in? Are you just playing at home,,, are you in a super heavy loud band,,, can you provide an example of the tone or type of distortion you are going for?
     
  15. markjazzbassist

    markjazzbassist Supporting Member

    Apr 19, 2005
    Cleveland, OH
    I've owned a bunch of bassmans. try 2 things for me

    - turn your channel gain all the way to 10. use the master volume to lower or raise your volume level, leave the gain dimed.
    - jump channels. Meaning plug the second plug on each channel into each other, now you can use all the knobs together. Again I would crank both channels gains and use the master volume to do your volume level.

    I've found that gives me enough color and drive.
     
    cman808 likes this.
  16. markjazzbassist

    markjazzbassist Supporting Member

    Apr 19, 2005
    Cleveland, OH
    that is for worldwide use. so keep on 117 for the USA and if you book a world tour the 220 and 240 would be Europe. Basically your unit has a power transformer that supports multiple voltages.

    That has nothing to do with the sound.
     
    cman808 and hennessybass like this.
  17. Rick James

    Rick James Banned

    Feb 24, 2007
    New Jersey
    If you're running volume and master both at 10 without breakup your pickups are too weak.
    Don't bother using both input channels, they're parallel, so the voltage drive won't go any higher. If you cascaded channel 1 into channel 2 that would work, but you need to mod the amp to do that.
    To get maximum grind the master needs to be set low, the channel volume high, and you need a hot enough input signal. Without modding the amp or going to much hotter pickups your alternative is a boost pedal.
     
    wcriley likes this.
  18. cman808

    cman808

    Mar 5, 2014
    That's great thanks :)
     
    markjazzbassist likes this.
  19. cman808

    cman808

    Mar 5, 2014
    It's likely that -- the amp is too clean for what I'm looking for. I have a 60s b15 fliptop and was looking for a similar sound (the fliptop starts to break up after 50% volume) but with higher output -- I mean, I know the 60s flip tops have a signature sound that likely can't be replicated using a bassman 100 (without the use of effects), but I wasn't expecting it to be this clean!
     
  20. hennessybass

    hennessybass

    Oct 11, 2008
    Houston, TX
    You just have to find that balance of breakup vs volume. I have an old B15, and have used it on lots of low volume gigs. Used it on some louder gigs with an extension cab (so 2x15). Lots of good volume, but still broke up earlier than I like and just didn't have enough volume. I gigged a Ashdown Little Bastard with 215s, (30 watts, same as the B15), but it broke up way more than the B15, and the breakup didn't sound as good. Just different amp designs. The Ashdown lost a lot of low end and tone. My Bassman 100 with my Berg CN212 is just the sweet spot for me in terms of volume / breakup. The V4B broke up too early for me.

    If you are not into getting another amp, try a pedal... I would think something like a VT Bass, Pork Loin, Fairfield Barbershop, etc... Something that is not a super saturated, but can give you a little breakup and a lot of gain. Look for an OD, not distortion. Keep the dirt low, and the gain high, this way you can push the amp, and get the most out of what you have.

    I'm thinking one of the new Ampeg Portaflex PF-50T might be right for you:D.
     
    markjazzbassist likes this.

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