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Kay tube combo

Discussion in 'Amps and Cabs [BG]' started by Plain Old Me, Sep 8, 2005.

  1. Plain Old Me

    Plain Old Me

    Dec 14, 2004
    There was a local ad I dug up today for a Kay tube bass amp with a 15 inch speaker. I love my tubes, and I'd love to replace my all SS combo with a tube one. But I could find no info on this amp... Anyone know anything about it?
  2. From a collector's standpoint, this may be a nice little combo. From a gigging bass player's standpoint, I believe you may be sorely disappointed if you expect to play this amp live.

    All the Kay amps I've seen have been low-powered practice amps. The Kay (and Harmony, same circuit) guitar amps such as the 405 and 505 were cute but only put out about 5 watts. I recall seeing schematics of some larger amps that probably put out 20 watts but to the best of my knowledge they never made anything much bigger.

    I've got an old amp that's a copy of a Kay guitar amp. The tone--for guitar and harmonica use--is pleasing, despite the lack of reverb. Surprisingly loud, considering it's only 4 to 5 watts. But for bass mine would be unuseable....

    If you do get it (hey why not if the price is right) here's some things to be aware of:

    -The very first Kay and Harmony amps didn't use a power supply transformer. These were notorious for having 110 volt wall current on the amp's ground. Don't worry, it'll only kill you if you touch something that's grounded...like a microphone, or somebody else's amp, or a wall switch.... :eek:

    -The electrolytic capacitors are probably getting very dry if they have not already been replaced. For a tech or knowledgeable do-it-yourselfer, a cap job should be easy. Do it or pay somebody else to change the caps. Dry caps may fail catastrophically, and I mean catastrophically--there's high voltage on them. I'd do a cap job before playing the amp at all. Caps should cost less than $40 for the parts.

    -The tubes are getting somewhat hard to find on some of these. For example, mine uses a 50L6 for the power tube.

    -The speaker may be getting pretty old and worn out. Some of these old amps had a field coil on the speaker, which makes finding speaker replacements more difficult.

    So to sum it up: if the exterior is in great shape (Tolex and grill cloth good, no corrosion on metal parts, all knobs there and in good shape) this may be a neat little amp to fiddle with and they are gaining collector's status (why is another question....). But don't expect an Ampeg SVT.
  3. Plain Old Me

    Plain Old Me

    Dec 14, 2004
    I really did not plan on playing it live at a gig of any volume, but I want it to be able to play over a drummer. It says 120 watt 15 inch speaker...

    It says 120 in the classified... I'm not sure if its right or not.

    Its $150, and I'm thinking for $150, you can't go wrong with a vintage tube amp.

    It says it was a 1963 model, do you know if this is too early for the transformer? Also, I plug everything into a good power strip made by Monster Cable, would that make the room safe? If not, my practices could get a lot more interesting, and possibly fatal :meh:

    I was thinking of possibly just taking the electronics out and making this a head to pair with a small cab for practice, and possibly recording. I'm thinking that the worn out speaker is a given. I dunno if the combo has an open back ( :eek: ) or not, but if the speaker isn't worn out I'll see what I can do with this thing...
  4. I suspect the 120 watts would be the amount of power the amp draws from the wall, not the amount delivered to the speaker!! For example, mine draws 25 watts from the wall, but only delivers 4.5 watts to the speaker.

    By 1963 it probably has the power supply on a transformer. If it didn't though, even a power conditioner won't help, the chassis would be hot if the wiring is reversed at the amp's plug.

    I'll look to see if I have a schematic, if you know a model number that would help.

    I'd offer 100 maybe haggle up to 130 or so, if the amp is clean....

    If the original speaker doesn't have the integral coil, I'd take it out, save it, and plop a generic 15 into its place, rather than pull the head from the chassis....
  5. Plain Old Me

    Plain Old Me

    Dec 14, 2004
    The only info he really gave me was the wattage, the year (1963), and that its got a 15 inch speaker. I shot him an email and expect for him to get back to me tomorrow, but I doubt he knows what he has got; he probabally pulled it from his grandfather's attic. If the chassis is a good, clean one, I think I might just replace the speaker as you suggested. The reason that I'd go with a head and cab is because I have noticed a lot of old amps aren't sealed or ported; they are just open and that just won't play a low B very well :meh: . By the way, what difference is there between a normal modern speaker and a vintage one with a field coil? I didn't know such a thing existed... Is the wireing between the speaker and the amp any different?
  6. A very good friend of mine has an antique tweed Kay with a 15 and it would be absolutely useless as a bass amp under any circumstances. Unless you want a $150 bookend, I'd stay from the Kay. For $150 you could find a silverface Fender Bassman 50 head and have something you could actually use (provided you have a speaker cabinet).
  7. Plain Old Me

    Plain Old Me

    Dec 14, 2004
    All I really want is a small practice amp... Lugging along my speaker cab with a Bassman kinda defeats the purpose. If this thing is useless in any circumstance, I will just not get it.
  8. I've got some schematics. The 720 has a pair of 6L6's and shows a 15 inch speaker. The only other model (that I have a schematic for) that has a pair of output tubes is the 830 but it doesn't show what the speaker size is. All the other models only have a single output tube.

    With a pair of 6L6's it might put out 22 watts or so.

    This link explains the theory of field-coil speakers. While smaller devices (such as radios) migrated to permanent magnets relatively early, in the music instrument business field-coils stuck around for many years.

  9. They look cool, but that's about it. I wouldn't waste my time if I were you.
  10. tombowlus

    tombowlus If it sounds good, it is good Gold Supporting Member

    Apr 3, 2003
    Fremont, Ohio
    Editor-in-Chief, Bass Gear Magazine
    If you want an inexpensive, simple-but-cool, tube 1x15 combo amp, see if you can find anyone selling a used Pignose B-100V. I bought mine off the 'bay for about that price, and it's a surprisingly good 100w tube combo amp (once you swap out the really cruddy stock tubes). New, the B-100V's seem to be hit or miss, but I think I've seen them under $500, which still isn't a bad price (for a new one).

    If you do get this Kay, though, you owe us a picture! :D

  11. AGCurry


    Jun 29, 2005
    Kansas City
    We're tryin' to tell you something here, Me.

    The ONLY practical value this amp will have is as a practice amp in your house. These amps were low in price and quality when they were made and they are no better now. By taking it apart you will only destroy whatever monetary value the amp has as a collector's piece, and it will NEVER handle a low B well even if you put it through a 18" sub.
  12. SamanthaCay


    Nov 16, 2008
    Denver, CO.
    that amp is a model 720 my 720 has been profesionally set up and i was told it was between 25 and 30 watts rms so no dice on keeping up with a drummer unless they no how to play soft or you had two kay 720's i use mine for practice recording low level jazz gigs and i also had a guitar player that f'en loved it all in all it's been a nice little amp that i've held onto for many years it has truely served me well now i also want to let you know tube amps requier mantnense in any case and can sometimes cost a pretty penny my advice is if tubes are gonna be your thing find a good and honest repair girl/guy and keep some money set aside to pay for the worse if you gig with a tube amp eather have a back up amp or air duster and extra tubes for a quick change oh yeah you'll need fuses to if you can afford all that jive tubes are the way to go:):):)
  13. Turock

    Turock Supporting Member

    Apr 30, 2000
    That is quite a lengthy sentence.
  14. And quite a lengthy pause between posts 12 & 13. :ninja:
  15. JimmyM


    Apr 11, 2005
    Apopka, FL
    Endorsing: Ampeg Amps, EMG Pickups
    Periods are your friend ;)

    So how come this Kay isn't gigworthy but a B-15 is? A B-15 only does 25 watts and has two 6L6's. And don't say it isn't because I regularly gig with one in a fairly loud band with a hard hitting drummer. And what's this about an air duster and extra tubes? I've gigged with tube amps for decades and never had either. Methinks you're exaggerating the difficulty of keeping a tube amp. A lot.
  16. Hi.

    In this case perhaps ;). Generally NO, quite the opposite.

    As the iron is (& was) the most expensive part of a tube amp and as the A-Fe more or less determines the f3 point, a skinny & cheap OT with a f3 of 120Hz or thereabouts won't sound too good with bass ;). Or with guitar for that matter if cranked.

  17. JimmyM


    Apr 11, 2005
    Apopka, FL
    Endorsing: Ampeg Amps, EMG Pickups
    Ah, OK...yeah, I didn't take the transformers into consideration.
  18. pfschim

    pfschim Just a Skeleton with a Jazz bass

    Apr 26, 2006
    SF Bay Area
    Hey Jimmy, I know you are a very experienced B-15 guy, and I would never dream of contradicting you :D, but I thought the B's were more like 37w, not 25 (??)

    In any event the Kay is not gig worthy in any sense. A friend of mine had one that we used in the late 70's as a distortion "top" .. for a JBL 1x15, because that little mother would just cry with any sort of volume level into it. But stand alone .. 'fergit it.

    Cool looking little amp if your into the vintage thing though
  19. JimmyM


    Apr 11, 2005
    Apopka, FL
    Endorsing: Ampeg Amps, EMG Pickups
    Well the B-15N started out as 25w, but they switched to a fixed bias in (I think) 65 so it got a boost to 30w. There were other Portaflex models, though, so it might have been another one of them you were thinking of.