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2x15 Portaflex Fliptop Cab?

Discussion in 'Amps and Cabs [BG]' started by bluehevy75, May 17, 2012.


  1. bluehevy75

    bluehevy75

    Dec 1, 2007
    Chicago, IL
  2. RickenBoogie

    RickenBoogie

    Jul 22, 2007
    Dallas, TX
    In the quest for more volume, more speakers will normally win the race faster than more wattage will. Depending on what that 215 is loaded with, using 2 15's instead of 1, with the same amp, will be noticeably louder.
     
  3. bluehevy75

    bluehevy75

    Dec 1, 2007
    Chicago, IL
    The add says the speaks are JBL 2225J. Not speakers I know anything about. Do you know of them?
     
  4. check here:

    http://www.jblpro.com/pub/obsolete/2225hj.pdf

    nice high efficiency old JBLs, they're 16 ohms a pop so odds are very good that's an 8 ohm cab.

    Bet they'd sound good w/your B-15, but of course play through them first ;)
     
  5. Ric Vice

    Ric Vice Supporting Member

    Jul 2, 2005
    Olivette, Missouri
    Ampeg actually built a solid state 2x15 column version of the BT-15. The head was a rated at 100 watts, more juice than your B-15N does.


    The cabinet your looking at is the bottom half of that amplifier. There are lots of players using an extension cabinet with their B-15's, so yes it will work just fine since it's an 8 ohm cabinet. It just won't be as loud.

    Ric
     
  6. sedan_dad

    sedan_dad

    Feb 5, 2006
    Columbus,Ohio
    I have one too. Not bad at all. ddd%20004.jpg
     
  7. bluehevy75

    bluehevy75

    Dec 1, 2007
    Chicago, IL
    Thanks for the help...but...

    Oh boy...here we go....I have thought about this but I'm afraid the ohm thing is throwing me for a loop. Tell me if this is right:

    1. My current blue line head/cab is at 8 ohm + 8 ohm extension cab= 4 ohm at 30 watts
    is louder than
    2. my fliptop head + 2x15 ohm cab at 8 ohm = 8 ohm at 30 watts

    Is that right?
     
  8. Ric Vice

    Ric Vice Supporting Member

    Jul 2, 2005
    Olivette, Missouri
    I believe this is true, but you should post this over to the Jess Oliver thread, there are a couple of tech perts over there that will solve it for you pronto.
     
  9. the wattage (like the song :ninja:) remains the same, it'll be a function of the cabinet/drivers' efficiency vis a vis increased volume, not the impedance.

    Agree w/Ric, please check w/the Jess Oliver group as they'll have more info on specific pairings. Regardless of which way you go, sounds like a very nice rig you'll have on your hands :cool:
     
  10. coreyfyfe

    coreyfyfe Supporting Member

    Nov 19, 2007
    boston, ma
    Almost. The portaflex heads used series taps on the transformers two the two 8 ohm outputs were tied to a 16 ohm tap on the output transformer.

    With this 2x15 8 ohm cab, you would just use the main output from the B-15 into the cab and still get the same 30 watts with a noticeable increase in volume. My main amp now for my cover gigs has been my B15N (old 25 watt version) with an extension cab and I've been good with volume.

    Also, as Ric noted earlier, this looks like it was the cab for the solid state head (really cool looking heads) but they also made a B15NC which was a 2x15 column (not to be confused with the B15Nc circuit revision) and B15ND which came with an extension cab and used the B18 power section for 50 watts. Just to throw a little portaflex history at you.
     
  11. JMac- Wiskerface Designs

    JMac- Wiskerface Designs Terror headcase dude

    Jul 8, 2009
    Atlanta, GA
    Very cool looking amps!

    I almost bought one of these 215 SS portaflex's from a local Musicgoround, a few years ago. It was in excellent condition, and sounded pretty good for what it was. However, They wouldn't get right on the price so I passed on it.
     
  12. Ric Vice

    Ric Vice Supporting Member

    Jul 2, 2005
    Olivette, Missouri
    That's just amazing that a 30 watt tube amp will drive a 2X15. In one of the B-15 threads there is a picture of a BT-140 that someone owns. Maybe I'll be able to find it. Do you mike the cabinet, or are you running it alone?


    This particular cabinet is hard to figure, it's really wide like the BT-140 would have been to accept the SS head. On the other hand, it only has the single silver single trim which could possibly make it a B15NC Column. Somebody else can make the definitive call.

    Ric
     
  13. stiles72

    stiles72

    Mar 20, 2009
    Albany IL
    That is a BT-15C cab. Like Sedan_dad, I have one and I also have the BT-15ND (two seperate 1x15's). The 2x15 cab was used for both the 100 watt solid state BT head and also for the 50 watt B15 tube head. I love the sound of the cab with the stock CTS speakers, and I bet JBL's sound even better.

    '67 Solid State Catalog: http://www.talkbass.com/forum/attachment.php?attachmentid=247134&d=1327384649

    '67 Main Catalog: http://www.talkbass.com/forum/attachment.php?attachmentid=247335&d=1327462691
    '67 Main Catalog 2: http://www.talkbass.com/forum/attachment.php?attachmentid=247336&d=1327462691
    '67 Mainn Cataog 3: http://www.talkbass.com/forum/attachment.php?attachmentid=248085&d=1327801597
     
  14. JimmyM

    JimmyM

    Apr 11, 2005
    Apopka, FL
    Endorsing: Ampeg Amps, EMG Pickups
  15. jnewmark

    jnewmark Just wanna play the groove. Supporting Member

    Aug 31, 2006
    Stax 1966
    Third St. Cigar Records staff musician.
  16. bluehevy75

    bluehevy75

    Dec 1, 2007
    Chicago, IL

    I didn't quite understand the bit about tapping the output transformer.
     
  17. jungleheat

    jungleheat Inactive

    Jun 19, 2011
    DC
    Why? A home stereo that is loud enough to make your ears ring is probably only going to be pushing an average of 5-10w or so (with peaks of 10-20w). Now, an uncompressed bass guitar is going to take a bit more wattage, but the tubes will add some compression themselves (which is going to increase how loud the whole thing sounds).

    People underestimate the watt. Which is why you get crazy dudes on here asking how to get cheap 1000w heads to power their inefficient 200w cabs, instead of realizing if they had better cabs, they could run a 200w amp and never get close to running it flat out.

    Anyway, a big 2x15 cab loaded with JBLs will probably be pretty loud. JBL has always been in the business of making pretty efficient MI drivers (in the 100+ db range). I have a cab with a single M151, which is like 103db sensitivity, and I run it with my Trace 2x10 (no idea what that's rated), and sometimes when playing, I'm wondering if the 2x10 is actually on because so much of the sound seems to come from the 15.
     
  18. JimmyM

    JimmyM

    Apr 11, 2005
    Apopka, FL
    Endorsing: Ampeg Amps, EMG Pickups
    In the old days of tube amps, each speaker out is connected to a tap on the output transformer. These taps operate at specific impedances. With a B-15, each one is 8 ohms. But if you use both speaker outs, you will use both 8 ohm taps for a combined impedance of 16 ohms. Old SVT's work sort of the same, except each transformer tap is 4 ohms and they combine for 2 ohms. Nowadays most tube amps have a switch that lets you switch between impedances, but that's how they did it in the stone age.
     
  19. Crockettnj

    Crockettnj

    Sep 2, 2005
    North NJ
    I know what you mean, but if you stop to think it through, most of the noise comes from that first watt!

    The physics of it, in a practical sense, is that the first 100 or so watts is where its at. After that, add speakers.
     
  20. coreyfyfe

    coreyfyfe Supporting Member

    Nov 19, 2007
    boston, ma
    Depends on the gig. With the singer/songwriter's band it's usually just running solo and driving the room but we tend to play smaller rooms, and unless the guitar player brings his AC30 and decides to blow the place away it's usually enough. With my cover band I have the cab mic'd but really only for the in-ears, I don't think the sound guy really puts any bass into the PA unless we're in a big room and have the subs going.


    I had assumed because of the wide lid that it was the BT-15. With the single 15 cabs there was definitely a double trim used for the solid-state heads, but I'm not sure on the column. They all seem to have single trim when just from a google image search:

    [​IMG]

    bt-15c-5000.jpg

    [​IMG]

    [​IMG]

    [​IMG]
     

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