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Ohm ... Ohm on the range.....

Discussion in 'Amps and Cabs [BG]' started by 11guitarguy, Feb 7, 2016.

  1. I'd really appreciate some help in understanding my amp/speaker/ohm question.

    I have a Hartke HA2000 with a 4x10 (8 ohm) cab. the manual says I will get 130 W from an 8 ohm load and 200 W from a 4 ohm load. Now I understand this (Two 8 ohm cabs = 4 ohm load) Everything is clear up to this point.

    The Hartke 4x10 and an Ampeg 2x10 cab is my current configuration and everything is cool with that. BUT... I have one more Ampeg 2x10 cab (also an 8 ohm) I hesitate to add this because I believe it'll lower the ohms to about 2.

    My Ampeg speakers are rated 200W (these are the ones that are used with the Ampeg Micro VR) SVT210AV

    So my question is, "Can I do this without damaging the amp or speakers?

    As an alternative would I be better off getting an 8 ohm 15" speaker cab to use with the 4x10?

    Any recommendations/advice would be great appreciated. Thanks.
  2. samson3382


    Apr 26, 2009
    Boise, Idaho
    Does your amp say "4 ohm minimum" on the back near the speaker jacks?
  3. I think the math for 3, 8 ohm cabs works out to be 2.66 ohms. So if the amp minimum is 4 ohm then that's trouble.
    IMHO adding another 4 X, 8 ohm, cab to your current one is probably your best bet.
    You get amp power divided up evenly between all speakers. With a single 15 + the 4 x, half the power is going to the 15, the other half of the power is divided up between the 4 speakers in the 4 x cab. This can be somewhat limiting. Plus 4 x cabs move more air then a 1 x 15, so is louder. Though I'm not sure how much better it will be than with your current set up.
    mikeyjm2 and 11guitarguy like this.
  4. ArtechnikA

    ArtechnikA I endorsed a check once... Gold Supporting Member

    Feb 24, 2013
    Except your chain is limited by its weakest link. You can't turn up any louder than your 210's power handling, since it's getting half the available power. Meanwhile the 410 is loafing. You'd probably be just about as loud if you just forgot about the 210 and ran everything into the 410. Yes, it cuts the available power but you can use all of it...
    the others are correct on the math.

    No on One, Yes On Two.

    No. Se earlier reference to weakest link and single driver...

    Get another 8-Ohm 410. Probably not what you wanted to hear.
    There are some games you could possibly play with series-connecting the 2 210's to produce a 16-Ohm load, which could be matched with the 410, but my quick arithmetic suggests this would be somewhere in the 10-12-Ohm range probably leaving you off worse than you are now. But you would have a very impressive wall of cabs... You will not find a series-connection cable off the shelf anywhere. Couldn't really recommend this approach.
  5. Rule of thumb...
    Paralell cabs of different impedance (ohms) will result in the total impedance being lower than the impedence of the lowest single cab. A 16 in parallel with an 8 figures out to 5.33. That will work with a 4 ohm amp and get a little more power than using 8, but not as much as with 4. Though loudness between the three is accomplished much more with increased speaker cone volume than it is with watts. A 2x10 cab pushes almost as much air as a 1x15.
    The balance between all speakers getting equal power is still off with a 4x and a 2x, but not as unbalanced as a 4x + a 15.
    B-string likes this.
  6. As ArtechnicA mentioned, you can rewire the 2x10, but since it is already an 8 ohm cab, the two speakers are either 16 ohm each wired in parallel for 8, or 4 ohms each wired in series for 8. So the wiring choices are for an 8 ohm cab as it is now, or a 32 ohm cab. If I understand, you have 2 2x10 cabs at 8 ohm each? If you run those two you get a 4 ohm load for the amp. That gives you max power into 4, 10" speakers. With the one 4x10 cab at 8 ohms, you get less power out of the amp.
    Omega Monkey likes this.
  7. Not necessarily. Four 10s will have more surface area than one 15 but displacement (moving air) is the product of the surface area and the excursion of the speaker so it is possible for a single 15 to displace more air than four 10s because many of them have a longer excursion than most 10s. Of course, there are exceptional speakers with long excursions but those are not usually used on commercial cabinets.

    The bottom line is you can't make assumptions about displacement based solely on the speaker sizes. Excursion is the other half of the equation and it varies widely.
    HolmeBass, mikeyjm2 and B-string like this.
  8. Yes. Thank you for adding that.
  9. Thanks for the info. I'll stick with the 4x10 and be happy.
  10. If I run across another 8 ohm 4x10 cab I'll get it and try it out. Thanks for the info.
  11. BTW... I enjoyed your thread title. The punsters would use your title in the context of measuring the element resistance on an electric kitchen stove. But that would be the punsters, I'd never personally consider digging that deep for a groaner. :whistle:
    mikeyjm2 likes this.
  12. doesn't apply to OP's weiner amp.

    I would like to hear how you like a vertical AV210 stack.
  13. Good question: Well, as I said I have the Micro VR with two of the SVT210AV Cabs that let me get the full 200W out of the Micro VR. They sound good stacked but i prefer to spread them out about 6' apart in my home studio and it sounds "bigger" for lack of a better terminology. I also have a B100R and a B112 (I am an Ampeg fan) The Hartke was a "can't say no" deal on craigslist. See the photo. I got the HA2000, a 2 space rack drawer and the Rack Rider power and light unit in the SKB 6 sp rack and the 4x10 cab for $200. All the pieces were in excellent condition and to make things better the seller was 10 minutes from my home here in So. Cal.

    The only issue is that the fan in the Hartke 2000 is kind of loud but research showed me that it's a common trait of these amps. Once the music starts the fan volume is not an issue. I have heard of replacement fans that'll quiet it down and maybe I will check that out in the future.

    Attached Files:

  14. Go with the two 2x10's
  15. I do use the two 2x10's with my Ampeg Micro VR...do you mean I should use them with the Hartke instead of the 4x10 cab? Actually I should try that. thanks for the recommendation
    Old Garage-Bander likes this.
  16. Keep a close ear on the 210's. They are medium duty cabs and might suffer from the low end of the Hartke.
  17. Personally, i would forego the 4x10, stack the 2x10s vertically on top of each other and push 200 watts into a higher (and therefore easier to hear) 4 10' speakers. Cheers.
  18. Yeh, I was wondering about that too. The Ampeg 2x10's are rated at 200W but I gotta admit that the cabs are pretty light in weight at 26 lbs (12 kg) (if that actually is relevant)

    I haven't tried running any other amps through them yet aside from the one I hooked up to the Hartke. I play at low volume most of the time so I don't think I'd damage the speakers. I bet there's a real difference in sound since the Hartke's are aluminum coned.

    That being said: Do you know if I can run a high wattage amp like a 500 or 1000 watt amp with a speaker cab rated at 200W as long as I keep the volume low? OR would my 200W speaker "see" the high wattage coming at it and just poopie it's pants and die?
  19. If you have good hand control they will be okay. If you slap/pop or have a heavy hand you could have trouble. If the string contacts the pole piece it might be a short play. An HPF would be a very good thing to have and use here.

    Volume controls are not wattage controls, a loud signal can drive big wattage with the "Volume" down "low".
    bassfran likes this.
  20. Sharknose79

    Sharknose79 UNPAID greenboy/fEARful endorser

    Sep 15, 2011
    South Cackalacky
    I have nothing to disclose at this time.
    mikeyjm2 and Old Garage-Bander like this.

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