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Cabinet for a 8ohm 50 watt vintage bassman head?

Discussion in 'Amps and Cabs [BG]' started by fishmonkeystew, Mar 6, 2008.


  1. I've been searching high and low for some info about minimum wattage for bass cabs. I have a newly refurbished fender bassman 50w tube head, and I'm trying to find the right cabinet for it (it'll be my living room rig). I've heard that underpowering your cabinet can damage it over time. So how do I choose the right cab size? I'm thinking of 2X10 set-up-possibly a fender pro 2X10, but maybe an Avatar. Problem is, I can't even start to choose 'till I know what size I should be looking for, and everything out there shows max wattage not minimum. Any suggestions?
     
  2. No such thing as minimum. Using an underpowered amp run to within an inch of it's life for long periods of time is probably not a good idea, but an overspeced speaker box is not a problem. What is worth looking at is sensitivity. Those Bassman 50 heads sounds cool but are not very powerful, some modern hi-end cabs really want a ton of juice to get going.
     
  3. I have a '67 BF Bassman; it came with an OEM Fender speaker cable that IS literaly a piece of zip cord with a flat-head Fender-logo plug on each end, and the cab with it was a 2x15.

    You can use any cab with 8 ohms impedence and not worry about it - just suit your own ears...the issues have to do with how hard you drive the head and how sensitive the speakers are.

    The issue is not underpowering a cab, it's clipping the signal. If you push a head hard enough that the signal clips, you get a square sine wave where the head cuts off - and that cut-off can damage speakers, since they can't reproduce it.

    As noted above, if you use speakers with high sensitivity you will get a lot more sound out of the system without having to drive the head too hard. I would also note that in my old BF Bassman head, anything above about 5 on the volume knob puts the head into distortion/overdrive territory. For some users, that's considered a good thing.
     

  4. That's exactly my concern. So I'm trying to find a cab to fit that bill. But the majority of info out there is about hi-power equipment.
     
  5. I do have the original cabinet, sans speakers and any other electronics. So I do have the option of just buying a couple of 12" speakers instead. If I do that, I would like to add a horn to the set up, but that will require mod-ing the cab. I've heard some say that the original fender cabs weren't that great. I'm new to all of this and am trying to find a bit of direction, but I'm game to make any mods myself if they're worth it.
     
  6. Don't worry so much about the published power handling specs(watts), look for sensitivity(dB@1W/1M). Eden make a very efficient 2x10. I'd avoid anything much below 100. Some stuff will be down at like 95 or even lower. That's just gonna kill you with this head.
     
  7. Then REALLY concentrate on speaker sensitivity ratings. There is a significant difference between a speaker with 94 dB sensitivity and one rated 98 dB. For every 3dB in sound pressure increase, you must DOUBLE the power of the amplifier!

    here's a quote from the following thread at eCoustics:
    http://forum.ecoustics.com/bbs/messages/1/132151.html

    "...the sensitivity figure will tell you how loud a speaker can get given a specified input. It varies greatly from 80 dB at 1W and 1m to 104 dB at 1W and 1m. That 24 dB difference means that the more efficient speaker requires 1/256 of the power needed by the less efficient one to produce the same loudness (a factor of 2 for every 3 dB). So the first one all out at 100W is as loud as the other driven with 0.4W. Note that these are extreme numbers on both sides."

    That's why a difference of 3 to 6 dB in speaker sensitivity really matters.

    And you're right, the original Fender cabs weren't scientifically designed, they're boxes made to hold speakers. My 60's 2x15 cab is probably only half as deep as it should be - but OTOH, at least it is portable.

    If you have an original Fender cab made for 2x12's, I'd frankly (heresy coming here) ignore all the stuff about designing cabs, etc. and get a couple of the more sensitive 12" speakers I could find and throw 'em in there. (Heck, buy 'em on Ebay.) Forget about adding a horn - that cab wasn't designed for one. What you should end up with is a classic Fender-60's-cab sound. If you want a modern sound with a horn, buy a modern cab....don't try to make that old Fender cab into something it's not. You might REALLY like the result.

    Manly exhortation: be a man, have a beer, throw some speakers in that old cab and just rock out with it. Arr, arr, arr. :cool::cool:

    Me? No horns, just 15" speakers and flatwound strings. That's the sound I like.
     
  8. asad137

    asad137

    Jan 18, 2007
    Minneapolis
    Physicist
    Incorrect. If speakers couldn't reproduce square waves/clipped signals without being damaged, every guitarist would have blown speakers every time they played using distortion.

    A clipped signal of a given peak amplitude contains more power than an unclipped signal of the same amplitude, and THAT has the potential to blow speakers. But with a 50W head, even a 100% clipped signal will only deliver about 100W into the speaker.

    Asad
     
  9. Thanks for the clarification - I figured that if I had cited that incorrectly, someone would correct it.

    Bottom line: clipping BAD. No go there. Bad juju.
     
  10. So, the higher the dB rating the more sensitive the speaker is? I may go ahead and just pick up some speakers, but this is my living room rig and one of the deciding factors is size (ie. how large of a cabinet can I go with before my wife gets aggravated). The original cab is about 4' long, so a bit bulky.
     
  11. lo-freq

    lo-freq aka UFO

    Jan 19, 2003
    DFW, Texas
    Speaker cabs: the higher the sensitivity, the higher the output level -- a couple of Bag End S15-D should work pretty well or a Bill Fitzmaurice Omni 15.

    Clipping most tube heads is not going to produce the really bad sounding crap that will come out of clipping an SS amp that doesn't have some type of limiter.
     
  12. For the living room, I'd suggest you pick up a 12" Avatar or other single speaker cab. You don't need a 2x12 in the living room...and there may be other circumstances in which a single 12 would be really handy.

    Wifely aggravation usually kicks in before the speaker cab gets to the size of a coffee table...and I don't blame 'em.
     
  13. Hehehe, too true, but I've been blessed with a wife with high tolerance for musical things. I've got a peavy 115 tko right now (which sounds like mega-crap) and that is about 3.5'X3.5'X18" and she doesn't have an issue with it. The 2X10 would be nice, cuz there is a chance that I will be playing with others (on a small scale). Does the extra speaker only affect volume? Isn't tone also affected?

    BTW, thanks for all the great feedback here. I'm new to this forum, and its been a wealth of info.
     
  14. I have a silver-face Bassman 50 and I use a Sonic compact 1 X 15" cabinet that is loaded with a JBL (M-3) speaker from a PA that works very well (much better than the D-140 that was in it when I bought it). I sometimes use it to gig with in smaller clubs but I have used it (obviously, with a DI) for several decent sized outdoor blues festivals and it was just fine functioning as my stage monitor.
     
  15. I was just checking out some eminence delta speakers with a sensitivity of 96.9. That seems to be about what I'm looking for, no? The Avatar B210 comes with these speakers. Not a bad price, either.
     
  16. Strikes me as a bit on the low side for a 50 watt amp. My favorite 15 for a bass amp is the EVM15L. Published specs put that at 103db. Of course you would have to find one first, but that speaker in a TL606 enclosure is a great combination with a lower powered tube amp.
     
  17. Jazzman

    Jazzman

    Nov 26, 2002
    Raleigh, NC
    I use the B210 Neo with my 50W 6G6-B Bassman head for coffee house gigs. It works very well and gets pretty loud for a 50W head.
     
  18. pedro

    pedro

    Apr 5, 2000
    Madison, WI.
    True but they look so freakin cool.

    Ditto. But if you decide not to use the 2x12 cabinet shoot me a PM. :)
     
  19. BartmanPDX

    BartmanPDX Supporting Member

    I'm watching this thread because I've been considering getting a low-power tube head and a small cab for my living room.

    My question to the OP though is this: how loud do you really need a living room rig to be? Are you going to be playing with others? If not, and you're just using it to play by yourself, I doubt you'd end up pushing that amp too hard unless you buy a cab with really low sensitivity. I'd think most any 210 or 112 should provide plenty of volume (for my needs anyway -- you may practice at a much higher volume). When I want to play loud, I just go downstairs to my main rig, so volume on the living room rig isn't much of a consideration (again, for ME). Right now, my Bassman 25 gets more than loud enough, but it just sounds like poo irrespective of what volume it's set at. Still, I don't think I've ever gone above 5 on it.

    If I play really loud in the living room, it annoys the heck out of my wife (usually trying to watch TV or work), and it's her tolerance (as well as paycheck) that has allowed me to build a nice collection. No sense in needlessly enraging the "boss." :p
     
  20. billfitzmaurice

    billfitzmaurice Commercial User

    Sep 15, 2004
    New Hampshire
    Owner, Bill Fitzmaurice Loudspeaker Design
    Unfortunately that rating tells you very little in and of itself. The actual sensitivity and frequency response is determined more by the cabinet than by the drivers contained within. As far as SPL ratings stated by cab manufacturers there is no standard as to how those are arrived at, so there is no valid method to compare them. OTOH, every manufacturer uses similar (and often identical) drivers loaded in similar cabinets, and all have to adhere to the same laws of physics, so claims that seem out of line usually are.

    That said, there is no such thing as too high a power rating, so in your case it should be ignored completely. What you do need is sensitivity, and the best way to get it with direct radiator cabs (what everyone sells) is to use as many drivers as possible, with each driver in as much cabinet space as possible. I'd look at a 2x10 to start, from whomever makes the largest box size. Down the road if you do gig a second 2x10 atop the first would give you enough sensitivity for the stage.
    The alternative to direct radiators is horn-loaded cabs, which have far higher sensitivity, but that's only a DIY or custom built proposition.
     

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