Speaker switchout Need help!

Discussion in 'Amps/Cabs Tech Corner: Amplifier, Cab & Speakers' started by kfowler11, Jan 4, 2006.


  1. kfowler11

    kfowler11 Guest

    I've got a Celestian speaker I want to replace the stock speaker in my Peavey Classic 30. Couple of questions:

    1.) Do I need to drain the capicitors to do this. This model does not have a standby switch so what would be the best way to do this if needed?

    2.) Are there any other things I need to know before I do this?

    Thanks!
     
  2. Scumback Speakers

    Scumback Speakers Gold Supporting Member

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    1) No, filter caps don't need to be drained. Turn it off if you're concerned, let it rest overnight, swap the speaker the next day.

    2) You need to match up your new speaker's impedance with the old one for a direct swap (not to mention replacing a 12" with another 12", but that's kinda obvious), and also check to make sure the new speaker has the same frame hole/bolt mounting spacing (pretty standard for the last several years, so that shouldn't be a problem unless you go from an 8 hole stud to a four hole drilled speaker!).

    What do you have now, and what do you need for a speaker tone upgrade? Or, what do you think you're missing? I may not have a speaker that fills your needs, but if you posted what you'd like to get to, some of the other members might have some good suggestions.

    Include your tone needs, guitar/pickups used, and the style you play in, as that all plays a factor in what would be recommended.

    Good luck, and welcome to the TGP!
     
  3. kfowler11

    kfowler11 Guest

    Thanks for the response. The stock speaker is a Blue Marvel 16 ohms. I bought a Celestion G12-L35 8 ohms from someone off the forum. I don't know why by I just realized I'm going from 16 to 8 ohms. Can I still just do a direct swap? I thought you could go from higher to lower but not lower to higher in ohms. Any thoughts?

    This is really just an experiement to see what kind of tone I get. I've enjoyed the Classic 30 and some people have recommened swapping the speaker.
     
  4. kfowler11

    kfowler11 Guest

    BTW, Peavey's website says 30 watts into 16 or 8 ohms. The amp has an external speaker jack which I assume wiould be for another 16 ohm cab. So 2 16 ohms would give you 8 ohms in parallel, correct? Questions is can I run 1 8 ohm speaker?
     
  5. bob-i

    bob-i Member

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    Yes, the amp doesn't know the difference, it only know impedance. I think it'll sound great.
     
  6. sixstringslut

    sixstringslut Member

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    Be super carefull around the speaker studs. Nothing worse than ripping a new speaker. You may need to remove chassis if not enough clearance.
     
  7. John Phillips

    John Phillips Member

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    You shouldn't just replace the 16-ohm speaker with an 8. The amp will operate at 8 ohms with two speakers, but that's because plugging something into the extension speaker jack switches it to another output transformer tap - simply replacing the 16-ohm speaker with an 8 doesn't do this and you'll be running at the wrong impedance. While it's usually safe to run a tube amp into lower than the correct impedance, I'm not sure I would try it with a C30 - the OT is very small and might not handle it.

    IMO you shouldn't do it anyway - the G12L-35 is IMO a poor speaker and no upgrade over the Blue Marvel (it's probably a lot worse). If you want a good speaker that will make that amp sound better, try a Celestion V30 or Classic Lead 80, one of the new Eminences, a Weber or something from Jim (Southbay). You should be able to get any of these in a 16-ohm version.
     
  8. samwheat

    samwheat Member

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    output transformers have impedance ratios meaning say in a marshall 50w plexi that a 16 ohm speaker is reflected back on the tubes at 3400 ohms when the selector is switched at 16 ohms .... with that said, by switching the impedance selector for different cabinets, you get the proper reflected impedance reflected back on the tubes per the "optimum" design

    now "optimum" design is based on a "load-line" analysis whether it be PP or SE taking into consideration the tube and plate voltage ..... all that work is done for you when looking at tube data sheets

    never plug into a 16 ohm cab with the selector in 8 or 4 ohms ..... this will result with high voltage on the power tubes and cause arching in the tube itself or at the socket

    you can go the other way though because the reflected impedance will be less ..... 8 ohm speaker where the OT is designed for a 16 ohms speaker ....... but the performance may not be to your liking

    I always plug into cabinets that use the full OT winding, hence all cabs are 16 ohms ....... whether or not I get that sonic nirvana is another story ..... LOL ...... I should be practicing now

    sorry i can't help you with a speaker selection because i don't play production amps ...... i build for myself

    weber silver bells have a nice greenback flavor with an enhanced mid hump

    weber 1230-55's are like the g12h-30's ...... hendrix used them ..... gobs of lows and nice highs

    i only buy webers because they're american made and i like them
     

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