suggestions for replacement 12" drivers to put in a vintage cab

Discussion in 'Amps [BG]' started by webmonster, Aug 17, 2013.


  1. webmonster

    webmonster

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    May 19, 2013
    Location:
    New Zealand
    I have a vintage Jansen (NZ) 2x12" cabinet from the late 1960's but its original Philips drivers really don't sound very nice for bass or (especially) guitar with any of my amps.

    Does anyone have a suggestion for some good sensitive drivers? I'd prefer good sensitivity because the matching amp is fairly low powered at 75W.

    I want to use the cab for bass or guitar.
     
  2. DukeLeJeune

    DukeLeJeune Only immortal for a limited time Gold Supporting Member

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    Owner & designer, AudioKinesis; Auth. mfg, Big E (Home Audio only)
    Generally speaking, guitar cabs aren't good candidates for conversion to bass cabs. They are usually too small and not designed for the kind of internal pressure bass speakers generate.

    If you decide to go ahead anyway, I suggest the Eminence Delta Pro 12A. It has enough excursion for bass, is fairly efficient, and some guitarists like it better than the EVM-12L.

    Just for the record, this is why you don't want to use a guitar speaker that you care about for bass:

     
  3. webmonster

    webmonster

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    May 19, 2013
    Location:
    New Zealand
    Many thanks for your reply - I didn't see it 1st time around... apologies for that.

    This cab matches my Bassman head and was intended for bass or guitar back in the day. It features two vertically arranged 12's and a closed back with a 'port'...or perhaps just a vent.
    DSCF8860sm.jpg
    DSCF8862sm.jpg

    Internal dimensions are:W 21.1", H 32", D averages out to c.12" (sloping front panel)
    'Port' dimensions are 6.5"x 3.15"

    I only intend using my Jansen Bassman 75W head or perhaps the Selmer 50 with it - certainly not anything big or modern.

    The original Philips drivers can handle 20W each and Jansen recommended 2 2x12 cabs for bass. The Philips drivers are likely all they could source given NZ's very strict import restrictions at the time.

    Thanks for the youtube link - I'll show this to my students at school :)
     
  4. Codger

    Codger Supporting Member

    Joined:
    Apr 13, 2008
    Two Delta Pro 12As actually look pretty good in that cab, at least according to WinISD even with the given port area.

    The stock speakers look like they have Alnico magnets. Some guitar guys might like those, regardless of what they sound like. :)

    Re: the youtube video. So that's what "cone creasing" is - basically turns the cone into mush.
     
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  6. AstroSonic

    AstroSonic Supporting Member

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    Dec 10, 2009
    Location:
    rural New Mexico
    That cab has enough internal volume to justify using two 12's. You should review some DIY cab threads here to see the latest thinking on bracing. The back panel does look like it will need some attention. It won't add much weight, but will improve the cab's tone.

    You do have a major decision to make: With a fixed cab volume, bass depth and efficiency have an inverse relationship. If you go for maximum sensitivity you will give up some deeper bass. If you go for deep bass you will give up some sensitivity. With about 2 cf per driver (after accounting for the volume of the drivers, vents and bracing) you can strike up a reasonable compromise.

    Regarding the sensitivity/low power issue, 75w of tube power is more than enough in many situations. Certainly, you don't have power to burn, but for smaller venues (clubs, bars, etc.), a cab with a sensitivity around 100db/w/m would be more than workable.

    One last but important factor is your budget for the drivers.

    So, let us know how much you can spend, and what you would you would like to do with respect to sensitivity and bass depth. You might also let us know about any tone preferences like: bass tight or pillowy, scooped or aggressive miss, etc.

    Lastly, if those Philips 12's are not blown, you should have no trouble finding a home for them (and helping out with the cost of the new bass drivers). They are highly desirable drivers for guitar. Philips made some superb extended range 12 inch drivers back in 'alnico days'.
     
  7. basscooker

    basscooker

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    I bought a couple of these (in 4 ohm) and couldn't be happier. They sound great and have 97 dB advertised spl. You may find them a bit dark for hi fi, but they do vintage well. Guitar will lack sparkle.

    http://www.mcmelectronics.com/product/MCM-AUDIO-SELECT-55-2952-/55-2952


    If you model something better, of course these are moot, but for general vintage cab replacements they work well for me.
     
  8. seamonkey

    seamonkey

    Joined:
    Aug 6, 2004
    If they are Alnico, you might want to check into re-gaussing the magnets
    http://vancouveraudiospeakerclinic.com/alnico.html

    Places that do this are far and few. It just not needed with modern permanent magnets.
    Those MCM's are a good choice, but many times "Vintage" isn't about sounding as good as new. Fix the speakers to sound vintage.
     
  9. webmonster

    webmonster

    Joined:
    May 19, 2013
    Location:
    New Zealand
    I'll do a search for some bracing ideas. What about dampening - there's nothing there at present.
    The back panel is a pretty hefty chunk of timber - in the photo I've not got it installed.
    Hmmm. I'll have to have a think about this!

    I would like to be able to have the choice to use the amp/cab combination for smaller gigs. For around the 100dB mark the drivers would be 97dB each? (or better)
    My budget. Heh! you should have asked me yesterday. Today I got the invoice for the latest work on the matching amplifier for this cab...
    If I have to save a bit longer to get the most suitable drivers then I don't mind. However, I'm open to all suggestions.

    As for tone - you've got a lot of adjectives there ;)
    I've never really thought about describing it. If it helps I do particularly like the bass tone(s) you find in recordings of Jimi Hendrix, Beatles, Deep Purple, Jefferson Airplane.

    Really!? The Philips drivers have whizzer cones and I think they sound pants for guitar, especially my 360/12. The high treble response is not what I like, personally.
     
  10. webmonster

    webmonster

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    May 19, 2013
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    New Zealand
    Thanks for the link... and they're surprisingly inexpensive! Certainly worth thinking about.
     
  11. AstroSonic

    AstroSonic Supporting Member

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    Dec 10, 2009
    Location:
    rural New Mexico
    The Eminence Beta12-AII is a close match (in your cab) to your tone (band) preference. A pair of them should easily meet a sensitivity spec of 100db/w/m. It also just happens to be relatively inexpensive.

    A vented design tuned to 45Hz (two 4-inch dia. x 5 9/16-inches long vents) will produce mild peaking between 80 & 150Hz (good punch), and bass extension of F3/62Hz & f5/54Hz. A single driver will be excursion limited (75w) in the mid 30's. It has moderate, broad peaking above 1kHz - also typical of your preferred tone.

    The Eminence Delta Pro 12A is a close second. A bit more sensitive, about the same bass extension, but not as punchy, and about twice as expensive. Still a very nice tone.

    The Eminence Deltalite 2512AII has a little deeper bass extension, but has a more modern voicing (somewhat aggressive mids) - not really the tone you are looking for, but lighter weight.

    The Faital Pro 12PR300 would have a more JBL-like tone (D/K140) and would have about the same bass extension, and a little higher sensitivity (than the Beta 12A), but is considerably more expensive.

    Understand that any 12 inch drivers will 'work'. The inexpensive MCM driver is a great value if you don't have a particular tone (response) target, or if you can measure the TS parameters of the shipped drivers. This is because these drivers seem to vary a fair amount from their published specs (IME). I would also worry about reliability. The Eminence drivers (as well as Faital, B&C, etc) are typically delivered pretty close to spec, and any variation usually allows the target response to be met.

    RE, guitar use of the stock Philips drivers. The dual cone models are highly desirable after a 'whizzerectomy'. They have an alnico magnet, high sensitivity, (relatively) small diameter voice coil, paper voice coil former (light weight) and a light paper cone (with great breakup modes) - all highly desirable features.
     
  12. Steve Dallman

    Steve Dallman Supporting Member

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    East Central Wisconsin
    I've been using MCM speakers for years. I have a couple of the 350 watt monsters in my current rig, but they don't have much high end. (I use a 6" mid and horn). They take everything I give them. I have 10's, 12's and 15's. All would be great at 2-3 times the price.

    FWIW, the sensitivity specs are not always accurate. My 12's are listed as 96dB and in reality are probably 92dB. The ones linked may be accurate. There is a poster in the comments who often tests these and posts the tested specs. Still, highly recommended.
     
  13. webmonster

    webmonster

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    May 19, 2013
    Location:
    New Zealand
    Many thanks for the answers on this thread. Lots for me to think about.
     
  14. RS66LB

    RS66LB

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    Dec 29, 2012
    Location:
    Connecticut
    If you're leaning towards guitar you might want to check these out http://www.eminence.com/speakers/speaker-detail/?model=Swamp_Thang_16, however these are a bit more versatile when it comes to both guitar and bass http://www.eminence.com/speakers/speaker-detail/?model=Delta_Pro_12A
     
  15. webmonster

    webmonster

    Joined:
    May 19, 2013
    Location:
    New Zealand
    I'm almost ready to move forward with getting this cab going (...at last!)

    I can get hold of:
    Delta pro 12 - $267.00 plus gst each
    Beta12-AII - $145.00 plus gst each
    Celestion Heritage G12H (55) - $199 incl. P&P & GST (each)

    I am surprised to see the G12H's come up at this price. At first glance they don't seem silly to consider - these are the 'bass' model, 100dB sensitivity, only 30W clean power handling (more than the existing drivers though...)

    Comments welcome :)
     

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