maryoleary Posted July 15, 2003 Share Posted July 15, 2003 Can someone out there please help me with this impedance thing? I have a Hartke 3500 head with two speaker channels. One cabinet is a SWR Goliath III (4X10") at 8 Ohms and one cabinet a SWR Big Bertha (2X15") at 4 Ohms. What happens when I devote a channel to each one? Will I blow something out with the mixed impedance(s)? Can I piggy-back another (2X15") cabinet (impedance unknown)? Life used to be so simple. Thanks for any help. Link to comment Share on other sites More sharing options...
NickT Posted July 15, 2003 Share Posted July 15, 2003 I think you might run into a problem with the 4 ohm 2x15. If you run both the 4x10 and the 2x15 together it will bring the impedence down below 4 ohms (to 2.6 ohms I think) From memory the minimum recommened impedence for the Hartke 3500 is 4 ohms, though check your manual to be sure. If the minimum impedence is 4 ohms, then dump the 2x15 and replace it with another 4ohm cab. Your rig will the run at a happy and safe 4 ohms. If however the minimum impedence on your head is 2 ohms, then dump the 8 ohm 4x10 and get another 4 ohm cab. You will then be able to run a 2 ohm rig (or a 4 ohm rig if you only take out one cab). If the minimum impedence is 2 ohms, you should be safe running the 4 ohm and 8 ohm cabs together...however due to their differing impedences they will draw different amounts of power from the head and the rig may well sound unbalanced. I would never ever daisy chain a third cabinet. My view is that there is a reason why the manufacturer put two speaker outputs on the back of the head. IT'S DESIGNED TO RUN ONLY TWO CABINETS. The long and the short of it is...check the minimum impedence for your amp (the Hartke website doesn't give a power rating for the head at 2 ohms, leading me to think that the minimum impedence is 4 ohms) and then get two cabs, with the same impedence, to give you the minimum load for the head. Assuming that you can go no lower than a 4 ohm load...sell the 2x15 and get another 4x10 or maybe a 1x15. If you want to be really cunning...you could buy a 2x10. You would then have three different rigs at your disposal. A 240 watt (RMS) 2x10 rig for small gigs, rehearsals etc, a 240 watt 4x10 rig for bigger places and a 350 watt 6x10 rig when you need to really pump it out. Free your mind and your ass will follow. Link to comment Share on other sites More sharing options...
... Posted July 16, 2003 Share Posted July 16, 2003 The thought of a Hartke 3500 head attempting to run a 4x10 and TWO 2x15 cabs brings tears of laughter to my eyes. And let's back up for a second here, are you suggesting that you do in fact want to run 3 cabs with this head, or are you going to replace the 4x10 with another 2x15? Realistically, the 3500 head is going to have enough trouble pushing a 4x10 and a 1x15. It's only a 350watt head. Assuming you can get any kind of decent tone out of it in the first place driving all the stuff, the second you start to turn it up to performance volumes the low end is going to suffer tremendously. Now, why is it that you think you need all these cabs?? Even a 4x10 and a 2x15 is a pretty insane setup. Adding another 2x15 to that, or replacing the 4x10 with another 2x15 is going to be, well, way more than you'd ever need; unless you are playing a 50,000 seat arena. Personally, I'd go with the 4x10 and lose the 2x15 cab(s) all together. I'd also lose the Hartke as quickly as humanly possible and get a different head, but that's just me. Link to comment Share on other sites More sharing options...
_Sweet Willie_ Posted July 16, 2003 Share Posted July 16, 2003 Now if you had a 4-ohm 4x10 with 350W from the Hartke 3500 driving it, you'd have decent thump for most venues. If you like the sound of 15s, just run the 350W into the 4-ohm 2x15 cab and have an ol' skool kinda day! Now, Bump, go easy -- I used to have a Hartke head and I succeeded in getting some good tone from it! (But, yes, I do enjoy my current SWR sound better.) To answer the original concern -- if you want to run two cabs, you need two 8-ohm cabs. It can be okay to mix cabs of different impedances, but in this case I wouldn't recommend it since your 4-ohm cab and 8-ohm cab together in parallel will yield a 2.67 ohm load, and I'm guessing that the minimum your Hartke can handle is 4 ohms. Rawk on. spreadluv Fanboy? Why, yes! Nordstrand Pickups and Guitars. Messiaen knew how to parlay the funk. Link to comment Share on other sites More sharing options...
maryoleary Posted July 16, 2003 Author Share Posted July 16, 2003 Many thanks to NickT, Bumpcity and Sweet Willie for taking the time to help me out with such informative answers. I have just two more questions: What would happen to the amp and/or speakers if I lowered the "ohm load" to below the amp's capacity? Would something physically blow? Link to comment Share on other sites More sharing options...
fantasticsound Posted July 16, 2003 Share Posted July 16, 2003 Originally posted by maryoleary: Many thanks to NickT, Bumpcity and Sweet Willie for taking the time to help me out with such informative answers. I have just two more questions: What would happen to the amp and/or speakers if I lowered the "ohm load" to below the amp's capacity? Would something physically blow?Simple... you'd fry the amplifier's power supply. Running an amp below it's rated load is akin to you running down a steep hill. Eventually, you get going too fast for your legs to keep up. Then you wipe out. At least you can probably get up after the fall. Your amp won't be so lucky if you run too low a load. It's easiest to find me on Facebook. Neil Bergman Soundclick fntstcsnd Link to comment Share on other sites More sharing options...
NickT Posted July 16, 2003 Share Posted July 16, 2003 BANG POP FIZZ (smoke coming out of the back of the amp). PS: I hate that darned Tab key Free your mind and your ass will follow. Link to comment Share on other sites More sharing options...
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