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Portaflex 800 with single cab

Discussion in 'Amps, Mics & Pickups [DB]' started by 2F/2F, Feb 12, 2018.


  1. 2F/2F

    2F/2F

    May 26, 2009
    Los Angeles, CA
    Hello,

    I was wondering if you could help me figure out what the safe amp settings are for keeping an underrated cab in good working order.

    I'd like to get an Ampeg PF-800, one flip-top 15" cab, and one 15" LF cab (the non-flipping one). However, I'd like to be able to play the amp through just the flip-top cab on many occasions.

    I know that the head becomes 400W when running through the single cab. I know the cab is rated at 450W. I also know that this combination won't allow me to use the full power of the amp without damaging the cab and/or experiencing unwanted distortion. I don't need to use the full power of the amp with a single cab, however, it would be nice to be able to know the concrete limits of the single cab.

    My questions are: 1) Can it be calculated exactly what amp settings are safe for the cab, or is it just a trial by ear and common sense judgment? 2) Is the power output of the amp controlled solely by the master volume setting, or is it a combination of gain and master volume settings? 3) I assume that the gain and master controls are not linearly tapered (such that 50% on the knobs = 50% of the max). Is this true?

    The reason I want the 800 as opposed to the 500 is because I want an amp with a whole bunch of headroom. I've spent 20 years playing nothing but my B100R, which sounds perfect tonally, when volume is not part of the equation...but has inadequate headroom for many situations. Moving from a 100W 15" setup to 250W (the PF-500 through a single 15") doesn't sound like a big increase in headroom to me. Going from 100W to 400W is not gigantic either, but 4x the power seems like it might be an at least somewhat sizable headroom increase.

    Thank you in advance.
     
    Last edited: Feb 15, 2018
    Ric Vice and Max George like this.
  2. Ric Vice

    Ric Vice Supporting Member

    Jul 2, 2005
    Olivette, Missouri
    Shouldnt’t be a problem. All my heads are higher than the cabinets ratings.

    Ric
     
  3. sevenyearsdown

    sevenyearsdown Supporting Member

    Jan 29, 2008
    Sanborn, NY
    When you run one cabinet, you'll only be using half of the power of the amp. Each cabinet is 8 ohms. The amps output is 800W @ 4 ohms, 400W @ 8 ohms. You'll be just fine connecting a 450W, 8 ohm cabinet to the head.

    (2) - 8 ohm cabinets connected to the head equal a 4 ohm load, which will have the head operating at full power (potentially). The PF heads and cabinets are designed/rated to operate exactly this way (as our most manufacturers). That's why a single cabinet is rated for roughly 1/2 of the amps output.

    Keep the limiter on though to protect the speakers.
     
  4. 2F/2F

    2F/2F

    May 26, 2009
    Los Angeles, CA
    Hello,

    I understand that it's a 400 watt amp with one cab. My OP says this. I had been warned in a previous thread here that this amp can indeed blow a single cab, and that distortion levels will become unacceptable at less than half power on the amp (i.e. below 200 W). Hence this thread.
     
    Last edited: Feb 13, 2018
  5. sevenyearsdown

    sevenyearsdown Supporting Member

    Jan 29, 2008
    Sanborn, NY
    Well speaking in general terms here, the cabinet specs exceed what you would be pushing into them. The amps full output (with a single cab), which you will likely never use is 400 Watts. The cab is rated for 450 Watts. So in theory, you shouldn't have a problem. The manufacturer designs the whole series of cabs and heads with this in mind. The only reasonable way a cabinet rated for that much power would fail while only being delivered half of it's rating is manufacturer defect. Under "normal" operating conditions per the spec, it should not fail. It shouldn't even break a sweat. I don't know who told you that.

    I'm also making an assumption here that you got most of your information from the BG forum, because not a lot of us DB'ers use Ampeg (I do). Having said that, as far as distortion goes - unless you are diming the gain into the red (essentially over-driving the preamp) and disabling the limiter - you shouldn't be distorting the cabinet at half power. If anything, I would think you might be farting out the drivers with the low end of upright bass, in which case you need to EQ the bass knob down like all of us do (or put a HPF in your chain).

    The stories that you are hearing may very well be true, but be an exception to the rule. I can't imagine Ampeg would be selling that line in the quantities that it has if the products were failing when only being pushed to half of the design spec.
     
  6. 2saddleslab

    2saddleslab Supporting Member

    May 30, 2003
    Kentucky
    Been using a pf800 w/ a 1x12 for over a year. Works like a charm in small to medium size venues.

    thumb_IMG_0893_1024.
     
  7. Ric Vice

    Ric Vice Supporting Member

    Jul 2, 2005
    Olivette, Missouri
    One word of caution here. The Portabass Series used the earliest versions of the Eminence Neodymium
    speakers. Since you’re using DB it should be ok, but I wouldn’t push the cab exceeding hard.

    Ric
     
  8. sevenyearsdown

    sevenyearsdown Supporting Member

    Jan 29, 2008
    Sanborn, NY
    He's talking about the modern Portaflex series, not the old Portabass.
     
    Ric Vice likes this.
  9. 2F/2F

    2F/2F

    May 26, 2009
    Los Angeles, CA
    Hello,

    Thank you for your reply.

    I don't know what BG or DB forums are. The thread I am referring to was here on TalkBass. BogeyBass and JimmyM were the ones who cautioned that using a PF-800 through a 400W cab can be a recipe for unacceptable distortion, and possibly a blown cab if not using common sense. As stated in my last post in this thread, the half power thing was about distortion, not blowing the cab. I never said I got told putting half the PF-800's power into a single 15 would blow the cab. I got told it would distort, AND I got told that that head is definitely capable of blowing the 400W 1x15 LF cab, if you try. 450W isn't that much more, so I am treating it as basically the same rating.

    BogeyBass:

    "400 watt thermal rating, factory 1x15 specially stamped steel speaker hits 10% distortion closer or below half that at 200 watts. even lower for anything below 80hz, more like 80/100 watts. people think more power does wonders. single driver is single driver. add more drivers, 2x15 was the standard for awhile 410 being somewhat more typical since 80s/90s"

    JimmyM:

    "Never ever put blind trust in numbers! Always use your ears and your common sense. I believe Bogey is slightly underestimating the capabilities of that cab but he's not far off. 400w is the point at which the speaker will blow, not the point it starts noticeably distorting. And that head can definitely blow that cab if you're not careful. Sounds freaking great, though! Definitely my favorite of the solid state PF heads. Just know that if your cab sounds like it's about to blow up, it will."
     
    Last edited: Feb 15, 2018
  10. okcrum

    okcrum in your chest

    Oct 5, 2009
    Verde Valley, AZ
    RIP Dark Horse strings
    Your ears will tell you if your settings are good. Any large transient (don't drop the bass!) will still blow the driver, but that's the risk one takes in return for extreme headroom.

    Just how do you hear an increase in headroom? I'm guessing what you really mean is you don't hear the anemic clipping of the B100R. I got one of those as "backline" on an outdoor gig - no FOH support. I was sure glad I brought my PF-500 rig. :thumbsup:
     
    Last edited: Feb 16, 2018
  11. 2F/2F

    2F/2F

    May 26, 2009
    Los Angeles, CA
    By more headroom, I mean less fuzz and squishiness as I turn the amp up. Pushing my B100R, the sound gets too gritty, and I have to play sooooo delicately to have any of my right hand variation come through. The B100R sounds great, but the volume doesn't cut it in some venues. Real-world, I can't go direct or mic the amp. They aren't "those kind" of venues. This band is not "serious." I'm talking low-rent music venues, back yards, motorcycle club houses, etc. The sound people usually don't have the equipment to mic or hook up a direct line, and are so dumb, deaf, and lazy you wouldn't want them to anyhow. The B100R works fine in places with actual sound people and actual sound systems, but real-world, that's not the case with this band, and never will be. We're just a bunch of geezers who like to make a racket with our friends from time to time.

    The B100R leaves nothing to be desired in terms of tone. I've had it since new 20 years ago, and I've never kept another bass amp for any length of time, because none of them outdo it. No new amp will ever fully replace it. It's just that for some gigs, I need something that can get significantly louder without fuzzing out. I settled on the Portaflex line after many years of hemming and hawing.
     
  12. sevenyearsdown

    sevenyearsdown Supporting Member

    Jan 29, 2008
    Sanborn, NY
    I was in a similar situation as you with regards to the B100. I've been using one for a long time, from my old bass guitar days. It's fantastic for upright, and needs no preamp or buffer. Like you I eventually needed more fire power because I could never really on house sound systems for reinforcement.

    I ended up going with a PF350 and 2 SVT-210AV's. It sounds like you need more than that though. You should have more headroom than you'll ever need with 800 watts.

    If you are still worried about wrecking the cabs, I suggest getting a High Pass Filter. You might need one once you start pushing that much power with an upright. I still stand by what I said earlier though regarding the ratings. In my experience though, it's gonna be the low end causing you the most issues when you start pushing that much volume.
     
  13. 2F/2F

    2F/2F

    May 26, 2009
    Los Angeles, CA
    FWIW, I got the amp and the PF-115HE cab. Sounds good. I don't like the tone, or the tone controls, as much as the B100R, but I'll be able to adapt for my purposes. Also, it really isn't a whole ton louder than the combo. In fact, it doesn't seem that loud at all. With the gain set totally cleanly, I need to set the master at about 7–8 before I think, "OK, that's nice and loud." But the additional headroom is significant. It gives the tone a lot more solidity and cut through in the mix so it *seems* significantly more present, even though it isn't actually much *louder*. I am sure it will be better with an additional cab too. Not sure whether to go for a twin 115HE, or get the 115LF. My instinct is to go for the slightly different cab (the LF).

    Also, I plan on trying my B100R's preamp into the PF-800's power amp. That might prove nice. If it works out well, I'll get another B100R and make a head cab for the amp, so I can do the same at gigs when needed.
     
    Last edited: Mar 7, 2018
    Ric Vice likes this.
  14. okcrum

    okcrum in your chest

    Oct 5, 2009
    Verde Valley, AZ
    RIP Dark Horse strings
    FWIW, a 400W amp and an 800W amp (both solid state) will sound identical supplying clean 390W. Headroom is a myth created to sell more amp than you need. If you need the extra power, it's not head room, because you're using it. ;)
     
  15. Ric Vice

    Ric Vice Supporting Member

    Jul 2, 2005
    Olivette, Missouri
    While this is true technically, certian amps sound fuller to my ears. My Walter Woods Ultra and M700 than an amp built by a different manufacturer. As did a Walter Woods MI-400-8 vs my Walter Woods MI-100-8. Just my take.
     
  16. sevenyearsdown

    sevenyearsdown Supporting Member

    Jan 29, 2008
    Sanborn, NY
    Ahhhhh... chasing the B100R tone. I've been there. I'm still there. Don't what magic they built into those boxes, but I always thought they were insanely loud for 100W combo.
     
  17. okcrum

    okcrum in your chest

    Oct 5, 2009
    Verde Valley, AZ
    RIP Dark Horse strings
    It could also be the gear you spent the most on sounds best. That could be real, or it could be a placebo. ;)
     
  18. 2F/2F

    2F/2F

    May 26, 2009
    Los Angeles, CA
    Great amp. Only bass amp I've ever used for any length of time. Got mine new in '96 or '97.

    Was tempted by the B200R when it was released, but never got around to trying one.
     
    Ric Vice likes this.
  19. 2F/2F

    2F/2F

    May 26, 2009
    Los Angeles, CA
    Whatever any of that means, the amp I just got solved the problem I had with my previous amp, so I'm happy. Whatever the reasons or the proper terminology for them, the new amp can get just as loud (and even a bit louder) without any audible fuzz or squishiness (and I don't even want to find out how ear-crushing the new one can get when it has the *same* level of squish and fuzz dialed in as I often have to dial in on the B100R in order to get it loud enough to be heard). I call that additional headroom, meaning less squish and fuzz at the same apparent volume in the mix. Perhaps that is not the correct terminology, but again, problem solved via the new amp, so all is well.
     
    Last edited: Mar 7, 2018
  20. Ric Vice

    Ric Vice Supporting Member

    Jul 2, 2005
    Olivette, Missouri
    Well,
    I make it a point to buy my gear used on talk bass. Both the amps I’m using currently, were purchased for 50% less than new ones. I try, to let my ears decide what sounds best, not my billfold. Just my take. :) :D ;) with Double Bass

    Ric
     
    Last edited: Mar 7, 2018