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I have this old tube amp...anyone know anything about it?

Discussion in 'Amps and Cabs [BG]' started by FireBug, Sep 27, 2005.


  1. FireBug

    FireBug

    Sep 18, 2005
    Houston
    I have this amp I took off a guy a year ago and was wondering if you guys could answer a few questions for me. I'm doing some research on it now.

    The amp is a Challenger series. Model CHA 10. Series J-39.
    I can't tell exactly who it is made by because of some slight cosmetic damage, but it looks like it says "David Bogen Co. Paramus N.J."

    I can't find a date on the thing, but I know it is very old. I'm not sure if the tubes are original or not, but they are as follows: (1) RCA 6L6GB, (1) Sylvania 6AU6, (1) Ratheon 6AV6, and (1) RCA 6BW4/EZ81.

    The 6AU6 and 6AV6 are both shielded. I'm guessing its close to 25 watts because of the one 6L6 and it looks like someone tampered/replaced a midi in for a microphone. It has a tone knob with settings "Deep Bass, Mellow, Crisp, Brilliant."

    Do you guys think that with some minor ajustments it could become a small practice bass amp?
     
  2. Plain Old Me

    Plain Old Me

    Dec 14, 2004
    I'd try using other tubes for tampering; those ones sound vintage and may be worth a good deal of money... It sounds like you could pair it with a good cab and get a decent practice amp.
     
  3. FireBug

    FireBug

    Sep 18, 2005
    Houston
    Which ones and how much money?
     
  4. Passinwind

    Passinwind I Know Nothing Supporting Member

    A Bogen Challenger like yours could be made into a fairly wimpy bass practice amp (class A with one 6L6 may be only 10 watts or so given the model number?) , but would probably be far more fun as a harp amp. Take a look at Ampage (www.firebottle.com) for links relating to rewiring old PA heads for guitar or other musical instrument applications. Have fun!
     
  5. FireBug

    FireBug

    Sep 18, 2005
    Houston
    What was the amp originally made to do? It looks like the 6L6 new would be 80 bucks and I can't find any other tube models as the ones this amp takes. How much could they be worth and what would replace a 6AV6 and 6AU6?

    I can't even find a 6BW4/EZ81.
     
  6. FireBug

    FireBug

    Sep 18, 2005
    Houston
    My research tells me this amp was made around the mid 1950s. Anyone have any other information for me?
     
  7. Plain Old Me

    Plain Old Me

    Dec 14, 2004
    Just about all of em, but especially the 6l6. The other ones can be worth a lot to the right person, as they are no longer made. I dunno the exact monetary value though.
     
  8. jsbarber

    jsbarber Supporting Member

    Jun 7, 2005
    San Diego
    I have a pair of McIntosh MC30 monoblocks from the '50s. They are class AB, and each one uses a pair of 6L6s. They are rated at 30 watts and I use them for my home stereo. The speakers I use with them are not especially efficient, 88 db @ 1w1m, if my memory serves me. Anyway, my stereo plays plenty loud. So, for a practice amp at home you may be fine on power output, especially if you use an efficient cabinet. One caution: if it has not been used for a while do not give it a hard start, you need to connect it to an AC source with a voltage control so you can increase the voltage gently over a number of hours.

    Jim

     
  9. Passinwind

    Passinwind I Know Nothing Supporting Member

    Those amps were primarily meant for PA for schools and other institutions. Someone calling you in for detention would've used it, prolly. :cool: I used to do service for Bogen systems, and many have lasted around 40-50 years with no problem. The output transformers in most of 'em make them nearly worthless for musical instrument applications, but as I said they can make fun harp amps. Check out the link I posted for more info, plenty of people like to mess with these things.

    6AV6 and 6AU6 are readily available still. Just Google the numbers. They're very cheap as NOS too: http://store.triodestore.com/otpopsmaltub.html

    6BW4 is a rectifier, NOS ones go for ~5 bucks.

    Edit: comparing a McIntosh monoblock to a Bogen Challenger = a Ferrari F-50 to a Yugo. :cool:
     
  10. FireBug

    FireBug

    Sep 18, 2005
    Houston
    So if I were to find a midi adapter for an instrument cable I could use it as a micro bass amp? Is it possible to swap out the midi in to a 1/4 inch in?

    About how much did these little amps cost when they were new?

    You guys have been helpful. Thanks.
     
  11. Plain Old Me

    Plain Old Me

    Dec 14, 2004
    I doubt you have anything MIDI on that amp. MIDI is pretty new still, and would not have been around anytime near when that amp was made. MIDI digitizes the signal and records what frequency (and hence note) is being played so that you can make your bass sound like a different instrument or have crazy effects on it. To get a MIDI signal from bass, you need a digital unit to convert the signal to digital, and to think that this amp could do anything with the signal is very unlikely.
     
  12. FireBug

    FireBug

    Sep 18, 2005
    Houston
    The input looked like it had been tampered with. Maybe I'm not clear on what a midi input is. The input in this one im pretty sure is new and it is round with a three-prong input.
     
  13. burk48237

    burk48237 Supporting Member

    Nov 22, 2004
    Oak Park, MI
    Bogen was basically THE supplier for commercial (schools, restaurants) PA (public address) amps. They were very low headroom, designed for amplifying speeches, announcements and background music. They are not known for dynamic range because not much was called for in that application. As far as a bass amp, your car stereo would probably make a far better bass amp. The harp Idea sounds cool, or a low volume quick break up guitar amp for blues in the studio, maybe. If the tubes are original they might be cool for something else, but Bogen should not be confused with Macintosh or other high end stereo gear. Most Bogen amps were designed so a high school principle could announce the school assembly on safe sex, not much else.
     
  14. KPJ

    KPJ

    Oct 2, 2001
    Methuen, MA USA
    That is an XLR input. As stated earlier, it was most likely a PA amp, so it was fitted with an XLR to connect a microphone. Just because it has tubes, doesn't mean it will make a good instrument amp. Before transistors were invented, everything had tubes, radios, tvs, computers, etc.

    Tubes don't automatically make it a good amp.
     
  15. If that isn't an xlr input. It's a cb mic connector. which vary brand top brand. I recall in elementary school. seeing them make annoucments through a cb type mic. Most all of which are 4 pin connector.
     
  16. FireBug

    FireBug

    Sep 18, 2005
    Houston
    So maybe I could just junk it and sell the power tube...

    All the power tube says on it is RCA HI, 6L6 GC USA. You guys got any idea how much this thing would fetch? Is there a way to tell the year?
     
  17. FireBug

    FireBug

    Sep 18, 2005
    Houston
    Or for that matter, how long those power tubes last in Bogen amps?
     
  18. I wouldn't ever junk it. Like you said it's a fairly simple amp. It would make great practice to refurbish that tube. Just to have the experience and better knowledge. Never know when you will find that "diamond in rough" amplifier. May as well get the pratice. But then again I'm an "I did it" guy.
     
  19. Frankly I don't think that power tube is worth more than a couple of dollars. Tons of 6L6GC's are available new....
     
  20. A9X

    A9X

    Dec 27, 2003
    Sinny, Oztraya
    Yep, and even if it were a rare "valuable" tube type/brand, I wouldn't pay more than a couple of dollars for it unless you really know what your on about with tubes and have a good tube tester.
    I'd have to see a pic of it before I had a good idea of value, but 6L6's aren't usually worth that much, and because it has RCA on it doesn't mean it wa made by RCA as lots of manufacturers used to buy in from other maunufacturers if they got a big order or ran short.

    If the OPT is a distributed line transformer as most small PA amps were, then it's not going to be much use as an instrument am as the turns ratio on the OPT will be all wrong. A single ended 6L6, depending on exactly which model tube and where you decide the distortion is too much, will put out under 6W in pentode and about 2W in triode. The power transformer, the tubes and maybe the sockets could be salvaged and used as prts for a small amp a la some of the early Fenders or one of the projects at www.ax84.com

    Probably I'd just use the power trans and the 6L6 to start with and maybe the physical chassis. Replace everything else.

    NOTE: Do not attempt to work on a tube amp unless you understand the neccessary safe working practices with high voltages and have the shills to do so, or the close surevision of someone who does. The ~300V in this amp can easily kill you if you cop it across the chest.