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Do I have a matching issue or possibly a bad cab?

Discussion in 'Amps and Cabs [BG]' started by ack, Jan 9, 2012.


  1. ack

    ack Why Can't We All Get Along?

    Nov 19, 2006
    Somewhere near Raleigh
    Disclaimer: Before I get killed for posting another "matching" question, I have really tried to sort this problem out. I'm quite new to head/cab technology. Since I first noticed the problem (about a month ago), I've tried to isolate the problem, but I'm not much closer. I've sent the question to Peavey Tech Support on 12/31 and posted in the Peavey Amp Forum a few days later - no response to either.

    I figured it was time to hit the TB knowledge farm before I just bring it "somewhere" for inspection.

    Onward...
    I have two choices for amps:

    1. Mark VIII (600W @ 2 Ohms, 350W @ 4 Ohms)
    2. ProBass 500 (500W @ 2 Ohms, 350W @ 4 Ohms, 200W @8 Ohms)

    I have two 4 Ohm Cabinets:

    1. 210TVX (175W continuous, 350W Program)
    2. 115BX BW (700W Program [BW] or 400W Program) [Scorpion] – I’m guessing that since the tag
    shows “BW” that it has a Black Widow inside. The mounting ring around the speaker is round and black (I believe the Scorpion has flat sides and is silver).

    Symptoms:
    I've noticed that when I run both the cabs together, the TVX210 tends to sound nasally and fart a bit - even at low volume - after about 30 minutes. When I run either cab alone, they seem to behave nicely.

    I truly don't know if the 115 ever farts out - it's difficult to isolate the sound when they sit on top of each other.

    Obviously, I’d like to be able to use both cabinets at the same time with the head that is better suited for them. If I should be running a different 210 (or whatever), then that will also be good to know some recommendations.

    Question:
    Since they are both 4 Ohm cabs, will they be able to handle the 500W (ProBass 500) or 600W (Mk VIII) from either head if they are used together (at 2 Ohms)?

    Sorry for the rudimentary question, but I don’t want to blow up the equipment I have.
    Steve
     
  2. billfitzmaurice

    billfitzmaurice Commercial User

    Sep 15, 2004
    New Hampshire
    Owner, Bill Fitzmaurice Loudspeaker Design
    That indicates the amp is not happy with the impedance load, no matter what it's rating is.
     
  3. RickenBoogie

    RickenBoogie

    Jul 22, 2007
    Dallas, TX
    It's fine, but it doesn't quite work that way. you can almost just forget what the wattage ratings on the cabs are- but do pay attention to the impedance. You have a 2 ohm load, and both the Peavey amps can handle that, so no problem there. But back to wattage ratings- just use your ears. If a cab is straining or farting, you're pushing it too hard. That could be overall volume, but it could also be too much low frequencies, ie: EQ. Pay attention to what you hear, and forget about the wattage ratings, as they do not tell the whole story. Not even close. Edit to add- listen to Bill above- he's the man.
     
  4. ack

    ack Why Can't We All Get Along?

    Nov 19, 2006
    Somewhere near Raleigh
    Thanks for the quick reply.

    I understand what your reply means, but both cabs are rated at 4 Ohms - and the amp (currently, it's the Pro500) can switch between 8, 4 & 2 Ohms.

    Could it be that the "unhappiness" the amp feels towards the impedance load is a function is something being wrong with either cab?

    I only included the Wattage handling of the cabs up-front in case it would be questioned later.

    After reading yours and RickenBoogie's responses, I went back upstairs and re-EQ'd the amp to tone down the Lows a bit.

    One (possibly) key factor that I omitted is that I have an MXR M80 DI inline (bass > DI > tuner > amp). I've had it since day one, but I usually keep the "color" on and bump up the low frequencies to get a real warm tone.

    I just took the DI out of the equation. IF the cab(s) stops farting after the amp re-EQ, then I'll put the MXR back online and see what happens.

    I feel kinda stupid that I didn't take it out beforehand.
    Thanks for the help.
     
  5. billfitzmaurice

    billfitzmaurice Commercial User

    Sep 15, 2004
    New Hampshire
    Owner, Bill Fitzmaurice Loudspeaker Design
    I suspect impedance is the problem since it only does this with both cabs, and it takes a while to happen, indicating a heat issue.
     
  6. RickenBoogie

    RickenBoogie

    Jul 22, 2007
    Dallas, TX
    Just FYI, the MXR "color" button is a mid-scooped preset eq curve, and when engaged, it disables the 3 band eq. I never touch that evil button.
     
  7. Does it happen without the mxr ... They do have a high output
     
  8. ack

    ack Why Can't We All Get Along?

    Nov 19, 2006
    Somewhere near Raleigh
    "Does it happen without the mxr ... They do have a high output"

    Hey Tim,
    Yeah - it does - but (I think) only when I have both cabs working together.
    I've turned the "Color" Off the MXR and zeroed the EQ section - same thing (using both cabs).
    I've turned the MXR Off and I still get that nasally output if I dig in (even at low volume).

    Sometime today, I'm going to re-test everything:
    1 - Pro500 head & 1x15 cab only (with and without the MXR)
    2 - Pro500 head & 2x10 cab only (with and without the MXR)
    3 - Mark VIII head & 1x15
    4 - Mark VIII head & 2x10

    I also have a TNT130 in the room - not sure if I can use it to test anything on the heads/cabs (possibly the crossover function), but I just thought I'd throw it out there in case someone has an idea.

    I'm probably looking at (as Bill mentioned earlier) an Impedance issue, and it's probably the 210TVX. I don't know what it takes to fix an issue like that, but I'll try to report some results of any testing I can accomplish this afternoon.

    Thanks for the input.
     
  9. anderbass

    anderbass

    Dec 20, 2005
    Phoenix. Az.
    I'd try the 9-volt battery test to make sure both cabs/speaker cables are wired the same phase.
     
  10. BassmanPaul

    BassmanPaul Gold Supporting Member

    Aug 25, 2007
    Toronto Ontario Canada
    My first thought too!
     
  11. will33

    will33

    May 22, 2006
    austin,tx
    Sounds like you're on the right track and have enough equipment to do a real process of elimination. Hint, your TNT is another separate amp and speaker to help isolate problems. You may have to pull the amp out of the combo, rig some wires, etc. but that is available to you as well.
     
  12. I'll make that a third, nasily when played together and the increase in input wattage at 2 ohms you should have to turn down the amp(s) when used together.
    Positive of the 9 volt to the tip of the speaker cable plug should move the cone(s) out on both cabs.
     
  13. ack

    ack Why Can't We All Get Along?

    Nov 19, 2006
    Somewhere near Raleigh
    Thanks for 9-volt test advice.

    So, if I understand this correctly:
    - I connect leads to the pos & neg side of a 9V battery
    - I leave the 1/4" speaker cable plugged into the cab
    - Touch neg lead to the casing of 1/4" speaker jack
    - Touch the positive lead to the Tip of the 1/4" speaker jack
    - Watch to make sure the speaker cone pops outward
    - Repeat test on other cab

    I'll try to get this done this afternoon.
    Thanks again.
     
  14. You got it. The 9volt makes it easy as the battery terminals are easy to touch to the free end of the cable. :)
     
  15. ack

    ack Why Can't We All Get Along?

    Nov 19, 2006
    Somewhere near Raleigh
    A+ fellas!
    The 210 cone moves OUTWARD, the 115 cone moved INWARD

    Somehow, this makes me happy, but I'm speculating as to how I go about fixing the 115.

    Is it just a matter of me pulling the grill off, removing the speaker and swapping the leads going to the (+) and (-) terminals of the speaker?
     
  16. will33

    will33

    May 22, 2006
    austin,tx
    Yes, that's all you have to do.
     
  17. JimmyM

    JimmyM

    Apr 11, 2005
    Apopka, FL
    Endorsing: Ampeg Amps, EMG Pickups
    Yep, pretty simple.
     
  18. Yes.....but triple check it to make sure that's what's happening.
     
  19. ack

    ack Why Can't We All Get Along?

    Nov 19, 2006
    Somewhere near Raleigh
    Yup. Did that and had my wife verify.

    I swapped leads at the 115 speaker and tested.
    It now moves outward like the 210.
    Buttoned everything up and they sound great together.

    I'll put it to the test later.

    Thanks to all for the excellent replies. I know a little more about speaker polarity now, and how to test.

    Now, I have to put the Smoke Detector back together - that's where I got the 9V lead.

    Peace!
     
  20. Sorry about the smoke detector :D Be sure to go back to the Peavey site and post what you found out here. Surprised at the Peavey boys not catching on?!
     

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