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Speaker Efficiency -- Need your help

Discussion in 'Amp Central Station' started by Jeru, Feb 19, 2020.

  1. Jeru

    Jeru Tele-Holic

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    Just got myself this Princeton non-reverb with the intention of having a fairly light/small
    tube amp to gig with (bars, etc). Loved the tone when trying it out, love the tone still.
    But, went to practice (even without our drummer) and even with the volume (and tones)
    pretty well maxed out I didn't have enough volume to keep up.

    Was reading another thread, and posts by Wally and others got me thinking about speaker
    efficiency. I'm thinking that a more efficient speaker in the amp may well get me there..?

    https://www.tdpri.com/threads/deluxe-reverb-and-princeton-wattage.652888/page-3#post-7060652

    So -- Questions:

    1) What is the db rating of those blue-back stock (oxford? CTS?) speakers?
    (Pic Below)

    2) Is a speaker that is 3-6-etc db more efficient likely to solve my problem?

    Thanks.

    Obligatory pictures below are of 1) the amp, 2) The Stock Speaker
    and 3) the 12" Mojotone and baffle that came with the deal.

    Princeton 1.JPG Princeton 5.JPG Princeton 6.JPG
     
  2. Wayne Alexander

    Wayne Alexander Friend of Leo's Silver Supporter

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    A Princeton is not going to be loud enough with a speaker change to keep up with your current band. You’ll need a bigger amp, or you’ll have to mike the current amp.
     
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  3. LightningPhil

    LightningPhil Tele-Meister

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    Unless google has the answer, doubt you’ll find it.

    However, the little magnet suggests a low BL product, which in turn means low magnetic shove. In essence, this means relatively inefficient. Eminance has great info on their speakers. Suggest starting there.

    Does the baffle fit and it it for putting a 12 into the Princeton? If so, you may be able to gain about 6dB on some frequencies by swapping in an efficient 12” in place of an inefficient 10”. Emphasis on the “may” part.

    Suggest considering a good neo speaker. Makes picking amps up easier...
     
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  4. telepraise

    telepraise Tele-Afflicted

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    You're in borderline territory volume-wise. A good 100db 12" ceramic speaker should get you about 1 to 1.5 more numbers on the volume dial. Whether or not that'll be enough to keep up with a drummer is questionable. The only way to find out is to try. I have a new 12" SE PRRI (rated at 15 watts instead of 12) and with an Emi Allesandro it is way louder than you'd ever expect. Tilting it back or putting it on a stand to get it aimed at your head helps.

    There are plenty of boutique builders who produce amps not much bigger than that with 2-3x the wattage (6L6s, bigger tranny) but they're likely to set you back a pretty penny. Ultimately, you may need a bigger amp, but I'd hang on to that Princeton for a home amp.
     
  5. BobbyZ

    BobbyZ Doctor of Teleocity

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    First off has the amp been serviced?
    Does the cap can say "Mallory" on it?
    If so then 99% it hasn't been.
    If that hasn't been done or you don't know, get that sorted out first.
    After that the most efficient speaker you can stuff in there will make a difference. Eminece has several 10s in the 100db range.
    Might get you there?

    I know from using a Maverick, (an Eminece 12" with adjustable sensitivity from about 91.5 to 99 db) that sensitivity matters. They should put one if those in every music store so people can try them!
     
  6. Jeru

    Jeru Tele-Holic

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    No,
    I need to replace the cap can. I've built several amps and know how to do it safely. I can't understand
    why the prior owner's 'tech' would replace a 2-prong cord and put a mid-pot where the ground switch/cap
    was but not replace the filter caps. Oh well.

    Yes, lightningPhil -- that second baffle fits and houses a 12"

    Anyone know what the sensitivity is on those blue-label 'special design' speakers..?
    Google doesn't seem to want to give up the goods. If those are under 90 then I could
    pick up some serious volume putting a ~100db-rated speaker in there.
     
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  7. BobbyZ

    BobbyZ Doctor of Teleocity

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    Hard to say what those speakers are rated at but I'm sure they're over 90db. Maybe not much over if you mean the original speaker from the '70s. I'd guess at least 93ish?

    There's always the put a mic on it option too. Some years ago I cought an outdoor show my brother did. Knowing his amps, Princeton Reverb, 5e3 and 6g2 Princeton I was wondering how he was going to do it. He wasn't worried at all just brought the 6g2 they put a mic in front of it and set the volume on a monitor near him. That's how the pros do things, I'm not a pro but I learned something that day.
    Or buy a Twin Reverb, still dirt cheap and they'll cover about anything. I have two.:)
     
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  8. dan40

    dan40 Friend of Leo's

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    I would also agree that it is likely in the 93-95db range. A speaker with a 100-102db rating should make a notable difference. Picking a speaker that emphasizes the correct frequencies will also help you to "cut" better in the band. The Eminence Alessandro GA-SC64 is very popular in these amps and has a pretty high db rating. The Maverick is also a great sounding speaker that gives you the option of turning it down a bit when you need to.
     
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  9. bradpdx

    bradpdx Friend of Leo's

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    If my Princeton Reverb can’t keep up with the drummer, I replace the drummer. We’re too darn loud.

    Almost any high quality modern speaker will help - a Weber, an Eminence, etc. The original CTS speakers are no great shakes. If you add some gain to the front end, that will help as well.


    Sent from my iPhone using Tapatalk
     
  10. schmee

    schmee Doctor of Teleocity

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    Your Princeton should keep up, especially without a drummer, but if the band is playing loud metal or etc then NO it wont. A speaker will make a huge difference. I recommend a Weber 10F150 or F150T 50 watt. Better yet a 12F150T on the 12" baffle.
    Or an Emi of your choice with 1.5" or bigger voice coil and at least 50 watts. Legend 1258 would be good.

    It will make a huge difference. Those original speakers are pretty anemic.
    The other thing to get you there if you then need it is a clean boost. MXR Micro Amp probably the best for that.
    But if it's generally a loud gig, the Princeton make not make it. It will be glorious for not too loud gigs though. Also, too much pre boost like a Rat etc will make the Princeton very ratty.
     
  11. 8trackmind

    8trackmind Tele-Afflicted

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    My princeton reverb keeps up just fine in a five piece rock outfit. I run a Eminace Ramrod in it. Rarely get past 3 on the volume knob. I don't remember all the specs however, it's allegedly over 100db sensitivity.
    You can't cook raw chicken with it like a Twin Reverb but its still loud.
    [​IMG]
     
    Last edited: Feb 19, 2020
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  12. jvin248

    jvin248 Poster Extraordinaire

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    .

    Open-backed cabinets are lazy designs.

    Go find the diy speaker cabinet design calculators (there are several) and match your speaker to a sealed cabinet. You'll get more output in a smaller volume (less weight) than open backed or ported cabinets.

    I've had this suspicion for a long time that amp builders size their cabinets on what looks right for the money to a buyer (it's big for big money, small for small money) and don't do any work figuring out how to maximize output for the chosen driver. Size the case for the speaker and amazing things happen.




    .
     
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  13. Jeru

    Jeru Tele-Holic

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    Thanks all. Very helpful.


    I hear you. My brother's PRRI is plenty loud. This old NON-REVERB Princeton stays clean up the dial, but just doesn't get very loud.

    Scmnee -- No metal. We play mainly Cumbia, some old country things and some ~"roots-type" rock.
     
  14. Jeru

    Jeru Tele-Holic

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    I thought about this too -- just something to get the input signal 'louder-ehough'.

    Been meaning to play with this concept with the pedals that I have on hand (mostly
    dirt boxes, but just to try out the concept with dirt at ~0). I have a homebrew SHO,
    but for some reason it raised the noise floor of the whole rig noticeably.
     
  15. uriah1

    uriah1 Telefied Gold Supporter

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    Well..keep the 10 baffle intact
    try a BD10 by Supro.
    Think 95 watts.
    Buddy of mine put in one of those
    emi crawdaddy , gator or cajun. thing
    He liked it..
     
  16. scout2112

    scout2112 Tele-Holic

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    Jupiter are great speakers which have 99+ dB sensitivity... 10LC ceramic and 10LA alnico.
     
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  17. schmee

    schmee Doctor of Teleocity

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    I play a Clapton Strat which has the mid boost, I often dont have the boost on, but the EC Strat is just plain louder even with it off due to the circuitry. It works very well for boosting a small amp. I've been using this for 20 years now with my DR or PR.
    As I said earlier, many OD type pedals make a PR too nasty if you are pushing it. I think it's just too much front end "pre amping" maybe. But the MXR does a good job. But first: Speaker!
    A more intensive change is to go with a DR output tranny, and even better headroom if you go for a bigger power tranny. It's amazing the head that adds.
     
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  18. 39martind18

    39martind18 Friend of Leo's

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    THAT'S that delicious smell when I use my Twin! :p:D
     
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  19. BobbyZ

    BobbyZ Doctor of Teleocity

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    You can also do a small rack of ribs.
    Just fold it around the four power tubes.
    A Super Twin with six power tubes would open up more possibilities. Come to think of it I just saw one for only 400 bucks. . . . . . .
     
  20. 39martind18

    39martind18 Friend of Leo's

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    A friend of mine back in the day used to have a PS 400- talk about multiples of tubes (6x 6551 power tubes, 435 wrms). A little aluminum foil, you cold bake bread!
     
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