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Walkabout with a 5751 tube

Discussion in 'Amps [BG]' started by jdelemus, Jan 10, 2013.


  1. jdelemus

    jdelemus

    Joined:
    Jun 27, 2012
    Looking to get a cleaner tone out of my walkabout head. Any one try putting a 5751 tube in one? Suggestions on brands or different tubes would be appreciated.

    I know guitar folks looking for more gain and a faster break up put in a 12ax7 in the first preamp tube spot. I'm thinking a 5751 might create less break up but am not sure and wanted to bounce the idea off the talk bass crew before spending money on a bunch of different tubes.

    What I am after is just a little more clean headroom.

    Thanks
     
  2. B-string

    B-string Gold Supporting Member

    Joined:
    Nov 21, 2008
    Location:
    Lake Havasu City, Az USA
    What is the original Tube type?
     
  3. Codger

    Codger Supporting Member

    Joined:
    Apr 13, 2008
    Amplification factor
    12AX7 100
    5751 70
    12AT7 60
    12AY7 45
    12AV7 41
    12AU7 19

    Need the circuit it is in to really calculate gain because there are other factors involved, tube's plate resistance and the external plate circuit resistance but these should give some idea.
     
  4. Jim C

    Jim C

    Joined:
    Nov 29, 2008
    If the input volume is at 12:00 or below, the fix is a more powerful amp.
    I rolled at least 10 tubes in V1 and the driver tube.
    If that thing had 500 watts or more I would have never sold it.
     
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  6. jdelemus

    jdelemus

    Joined:
    Jun 27, 2012
    The original tube type is a 12ax7
     
  7. B-string

    B-string Gold Supporting Member

    Joined:
    Nov 21, 2008
    Location:
    Lake Havasu City, Az USA
    The 5751 may do what you are looking for. 12AY7 and 12AU7's are also possibilities. 12AT7 have always sounded harsh to my ears.
     
  8. Jim C

    Jim C

    Joined:
    Nov 29, 2008
    jdelemus,
    Regardless of the tube at either V1 or the driver tube, the amp puts out 300 watts at 4 ohms max.
    Assuming that the tube is not defective, why do you think it's not the amp exceeding its' output power?
     
  9. two fingers

    two fingers You tahkin 'uh me? Yeah, you. You tahkin 'uh me? Supporting Member

    Joined:
    Feb 7, 2005
    Location:
    Eastern NC USA
    Wouldn't an amp "exceeding" it's output power be like a car "exceeding" it's maximum speed?

    Anyway.... I think the OP is talking about more in the gain than the output. I own a Walkabout and you can get it to break up a bit if you crank the gain with the stock 12AX7. I think he wants to be able to use the gain structure of the amp more without it breaking up.

    Also, I run mine in the Scout 15" combo and use a matching extension cab. It will take the skin off your face with the volume on about 3 and the gain about halfway up. A lot more goes into volume than watts.
     
  10. Jim C

    Jim C

    Joined:
    Nov 29, 2008
    I am completely confused as to what you guys are taking about.
    I had a WA.
    With s standard P bass clean tone ended with the volume and master at about 12:00.
    Thats where the power amp started to distort as it did not have enough power to create a higher SPL without distortion.
    When the volume was turned up past about 1:00 (regardless of master position) it would start to break up.
    I rolled approx. 10 12AX7's through this amp including some pricey original Telefunkens and Amperex tubes.

    The OP is looking for "Looking to get a cleaner tone out of my walkabout head."
    Could it be that the bass has a high output and the frond end is clipped without using the active input attenuator?
     
  11. two fingers

    two fingers You tahkin 'uh me? Yeah, you. You tahkin 'uh me? Supporting Member

    Joined:
    Feb 7, 2005
    Location:
    Eastern NC USA
    I think you may have been dealing with something else. Mine is labeled "Gain" and "Volume" not "Volume" and "Master". And as long as I back off the gain a little, I can DIME the volume and it stays just as clean as can be. I ran a fridge (Ampeg 8-10) that had been modded with bullet proof speakers and I thought I was going to knock the drummer off his throne. I had the gain about 1/3 up and the volume dimed. I ran it that way for about an hour. (Found out last minute there was no PA support at an outdoor show so I borrowed the other bands cab and the Walkabout KILLED volume wise.)

    Either way, there have been plenty of threads here about guys being able to get more or less breakup (cleaner or dirtier tone) depending on the model/brand of tubes they tried. Either your cab was a bad match, the bass had a problem, or there was something else not happy in your head (bass head that is). Something other than "lack of power" was the issue.
     
  12. Jim C

    Jim C

    Joined:
    Nov 29, 2008
    Glad to hear your opinion.
    Let's not get so pissy about the labeling on the knobs.
    You might read some of the many posts in the multiple WA threads with others who ran out of clean head room and sold their amps.
    I loved the tone but it was not a good match for clean power with either a 1x15 or 2x12 if high clean volume was the requirement.
    This was also repeatable with a SVT-CL although not a problem with a pre/power amp combo.
    I can totally believe that the WA would be much louder through an efficient cab like an 8x10.
    If you don't mind hauling the cab, I could see the WA as a good choice.
    My goal was trying to downsize to smaller, commonly available cabinets, and a micro (or slightly larger head).
     
  13. lomo

    lomo passionate hack Gold Supporting Member

    Joined:
    Apr 15, 2006
    Location:
    NE US/CAN line
    I have rolled about 20 tubes through my Walkabout. It responds very well and there are subtle differences to be heard. However, as Jim posted, it pushes 300 watts into 8 Ohms. If you have enough cone area (and/or if you like your tone with some grit, allowing you to push the gain past noon) it can get very loud. I like my gain at noon-1 o'clock with most of my basses. For me to have the headroom I like with the band, that entails either a 410 or larger in terms of cone area. With a 212 I have to push the amp to its' limit and do not have "luxurious" headroom.
     
  14. Jim C

    Jim C

    Joined:
    Nov 29, 2008
    Thank God I'm not loosing my mind, at least about amps :eek:
     
  15. jdelemus

    jdelemus

    Joined:
    Jun 27, 2012
    ...Perhaps I just need an amp with a few more watts. My experience has been the same as Jim C's. I get quite a bit of fuzz when the gain is past 12. My bass does have a high output but it also has an active passive switch. I get less distortion with my bass passive using the attenuated circuit which is what got me thinking a less gain tube might help.
     
  16. Dan55

    Dan55 Supporting Member

    Joined:
    Apr 26, 2006
    Location:
    Atlanta
    I think it's around 165 W into 8 ohms and 300 into 4. Fortunately for me, paired with an 8 ohm 410 does the job for me.
    At any rate, I think Chef found the long plate Sovteks ended up giving him the most gain before starting to break up. YMMV.

    Dan
     
  17. BawanaRik

    BawanaRik Supporting Member

    Joined:
    Mar 6, 2012
    Location:
    New Jersey
    I was a fan of the 12at7 for years. Until a TB poster started recommending the 12au7. I have to say for a V1 I like them.

    The audio folks have been using the 12au7 more than the MI side of things.

    Still use the at for PI and Reverb drivers.

    The 5814 is a 21au7 variant that seems to make folks happy.

     
  18. chaosMK

    chaosMK

    Joined:
    May 26, 2005
    Location:
    Albuquerque, NM
    Disclosures:
    Hi-fi into an old tube amp
    Go with a JAN. I was lucky to come across/obtain a few in another amp of mine. Works wonders on my Bass 400 and cleans up my D180 like crazy (I took it out though, I like it dirty and especially so for guitar).
     

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