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Bass Rig Set-up Question (already did some research)

Discussion in 'Amps and Cabs [BG]' started by bWaOsPs, Nov 24, 2012.

  1. bWaOsPs


    Nov 24, 2012
    Long time reader; just created a name and this is my first post.

    First off - just want to thank all the fellow musicians for sharing their info and knowledge. I've learned a lot by reading the threads here. My hat goes off to you.

    I'm in the process of buying a new bass amp. I've been borrowing one for a while now and my band just got some good news and a new member. It's time to upgrade. I've done research before posting this so I have a solid understanding. The question attends to amp/cab compatibility and headroom. So here's my deal:

    I have 2 cabinets that were pretty much given to me and they are each awesome. But I never hooked both up together. I primarily use a Hartke 4.5 XL (400 watts at 8 ohms). The other is a Hartke 210 TP (150 watts at 8 ohms).

    The amp head I'm looking to get is the Ampeg PF-500. It's specs are max 500 watts at 4 ohms and max 350 watts at 8 ohms. I want to have some versatility with my rig set up (if possible) so I can use just one or both.

    So here's my question.

    If I use just the 4.5 at 400 watts at 8 ohms, the amp will run at 8 ohms max 350 watts. That's 50 watts of headroom.

    If I use both cabinets I'll get 550 watts at 4 ohms, and the amp will run at 4 ohms at max 500 watts. That's also 50 watts of headroom.

    Is the amp I'm getting a good fit for my cab(s)?

    Is 50 watts of headroom enough? (I know headroom is the difference and I know going to low can sometimes damage the cabs by not getting enough juice; and going too high can blow'em - so there has to be a sweet spot, no?)

    Also, the difference in the headroom between both setup options are 50 watts. But does the difference in max wattage (350 vs 500) make one option better at the 50 watt headroom?

    I feel I may be over thinking this but better to be safe than sorry. If I'm buying a new amp, I at least want to check with people first. Thanks again for your help everyone. Rock on:bassist:
  2. Time for more research..............

    First off, the ratings of cabs are the thermal rating at which the voice coil will melt - NOT the real world mechanical limits which can be almost half of the thermal rating depending on how you EQ.

    Headroom usually relates to how much CLEAN power your amp has, NOT the cab ratings.

    Lastly, there is no such thing as underpowering a speaker.

    ETA - also noticed you want to run a 4X10 with a 2X10. When you do this, you need to have a 4 ohm 4X10 with a 8 ohm 2X10 so that each speaker recieves the same power (you will also need an amp that is 2 ohm stable).

    Doing it the way you want to (both cabs being 8 ohm), you will be sending the speakers in the 2X10 twice the power of the speakers in the 4X10 (a recipe for blowing the speakers in your 2X10)
  3. If you run both cabs together, I highly recommed you placing the 2x10 on top, and listening carefully, as that cab will be prone to blow. As both cabs are 8 ohms, they would both be getting a maximum of 250 watts, in the case of the Transporter that is almost double the acceptable maximum. Now, you can stll run both cabs with a head such as that, you just have to be careful.

    I've always thought about headroom as available power in your head, that is above and beyond what your current uses call for, that additionally your cabs can handle. For example, if you doubled up on your 4.5XL's, the sensitivity of the 8x10's might be such that you need to use very little of the PF500's available power, leaving you with lots of dynamic range. The cabs in that instance would very likely swallow everything the head can offer, leaving you with headroom. Getting an SVT 7PRo would then offer you roughly double the headroom at the same volume level.
  4. JimmyM


    Apr 11, 2005
    Apopka, FL
    Endorsing: Ampeg Amps, EMG Pickups
    Not a good idea to power both cabs off the same head. Besides, make no mistake...350w through a 410 can get quite loud. That is not what you would call a quiet rig.
  5. Or to save you a headache you could get yourself a nice ampeg 810 for a decent price off of craigslist which would pair nicely with that schnazzy new PF.. Just saying ;).
  6. lazyone2


    Jul 27, 2006
    new jersey shore
    The 4.5XL very good sounding cab goes much deeper then the 210TP. In the older Hartke cabs the XLs were top of the line and TP entry level. They are not a good match.
  7. Russell L

    Russell L

    Mar 5, 2011
    Cayce, SC
    Mismatching cabs is a crapshoot. Looking at the physics, what you would be doing is possibly straining the smaller cab while the bigger one is just cruising. Easy to blow a cab that way. Plus, due to each cabs specs you might get notes cancelled or boosted at certain frequencies, or there could be some other problem related to the way in which each radiates. Who can say? Sometimes it works fine, but it's more likely to at least not work as well as matching cabs. At low volume you'd be safe, but as the lows go up, and volume, the risks rise, too.

    If you don't mind hauling a 410, another one just like it would be best. Or, you might wanna rethink what you really want. I suggest considering a dual 1x15 set-up that will sound just as good, but would be much easier to get around with. Just a thought.
  8. Got a load of money! Get the Marshall double stack and Bass head. Now that is one rig!!!
  9. I'm with JimmyM, I always do one cab/one amp, which seems to work the best.
    I have ran my Orange Tiny Terror with 2 cabs, and it has worked fine with 2 twelves and one fifteen.
  10. RickenBoogie


    Jul 22, 2007
    Dallas, TX
    +1 to the general consesus. More knowledge needed, more research should begin. Listen carefully to these responses, can save you alot of headaches.