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Ohms FAQ

#581
I've read through everything in this excellent thread, but still found a way to ask a few questions specific to my situation.

At long last, I'm considering updating my rig and need advice. I currently have an SWR SM-400, an SWR Triad I, and an ancient Eden David D-210T. I generally run the SM-400 in stereo, with one channel to the Triad and one to the Eden, or I run the SM-400 bridged to the Eden. The Eden is conveniently labeled for 250 W/4 Ohm, which I've been ignoring, since the SWR delivers 400 W to 4 Ohm in bridge mode. I haven't managed to kill my little Eden yet, as I'm pretty careful.

So now I have a couple of questions. First, I'm thinking of going to a Genz-Benz ShuttleMAX 1200, which basically has two 600 W channels @ 4 Ohm. First question: can I continue to use my 250W/4 Ohm Eden with one 600 W channel of the GB, or will I kill the poor thing? Second question: the current Eden 210XST is rated at 500W/4 or 8 Ohm. Anybody know what's different about the new cab that doubles it's power handling capacity? Third question: with the G-B at 600W/4 Ohm per side, would I be better off with the 4 or 8 Ohm Eden, that is if, say, I had no alternative but to go with the new cab?

The thing is, I love my little Eden, plus I would prefer not to have to move into the garage, which might be necessary if I spring for a nice new little Eden. Hep me!
 
#582
Gimme5 said:
I've read through everything in this excellent thread, but still found a way to ask a few questions specific to my situation.

At long last, I'm considering updating my rig and need advice. I currently have an SWR SM-400, an SWR Triad I, and an ancient Eden David D-210T. I generally run the SM-400 in stereo, with one channel to the Triad and one to the Eden, or I run the SM-400 bridged to the Eden. The Eden is conveniently labeled for 250 W/4 Ohm, which I've been ignoring, since the SWR delivers 400 W to 4 Ohm in bridge mode. I haven't managed to kill my little Eden yet, as I'm pretty careful.

So now I have a couple of questions. First, I'm thinking of going to a Genz-Benz ShuttleMAX 1200, which basically has two 600 W channels @ 4 Ohm. First question: can I continue to use my 250W/4 Ohm Eden with one 600 W channel of the GB, or will I kill the poor thing? Second question: the current Eden 210XST is rated at 500W/4 or 8 Ohm. Anybody know what's different about the new cab that doubles it's power handling capacity? Third question: with the G-B at 600W/4 Ohm per side, would I be better off with the 4 or 8 Ohm Eden, that is if, say, I had no alternative but to go with the new cab?

The thing is, I love my little Eden, plus I would prefer not to have to move into the garage, which might be necessary if I spring for a nice new little Eden. Hep me!
Click to expand...

Not to nit pic but I believe you mean you're considering a ShuttleMAX 12 which has 2 x 600 watt power amps in it (along with two preamp channels). Each power amp outputs 600 watts at 4 ohms as you've noted above. Be aware that with an 8 ohm cabinet, each power module output drops to 375 watts. The nice thing with the SM12 is that you can run multiple combinations of ohm's to each separate power module in the amp. For example, 1x8 = 375 watts, 1x4 = 600 watts, 8+8 = 750 watts, 4+8 = 975 watts, or 4+4 = 1200 watts.

If I was going to have a ShuttleMax 12 driving a 410 cabinet, i'd want that cabinet to be rated at 4 ohms, to maximize the output power of one of the SM12's power modules.

Personally, I do own a ShuttleMAX 12 and I use it to drive my two (4 ohm each) 410 cabinets. This way both power amps in the SM12 are outputting their maximum capacity 600 watts each x 2.

I'm sure someone will come along and answer your other questions. If not, contact Jeff Genzler at GB through their website and ask him. He'll respond back very quickly.

Good luck.

TD
 
#583
I would first off just like to thank IvanMike for all of his info on this. I am building a bi-amp system and would appreciate it if someone could help me tie up the loose ends.. (specific questions at the end of my post).

I landed here because I use a 5 string bass and have been running it through an Eden Navigator and a QSC Plx 1602 (bridged to yield 1100w @ 8ohms) through an SWR 6x10 Goliath Sr. (1200w RMS @ 8ohms - from SWR website) for a couple years. Well, the low end (B string) is kinda distorted, not really clean, low thumping bass... "not really kicking ass" in my book. I learned in another thread thanks to Greenboy that my cab simply is not made for faithful reproduction of the low B and when I looked up my cab's specs, sure enough the low frequency range is about 25hz above what I'm looking for.

So I've come to the conclusion that I want to build a bi-amp system with a sub that is rated for 30hz and below. The cabs I'm interested in are the SWR Goliath 4x10 (800w - not sure if I should get 4ohm or 8ohm if they are both rated for 800w), and the SWR Big Ben 1x18 (400w 8ohm).

Ok finally, my questions! :hmm:
1.) In short, I think I'm gonna need a more powerful power amp! I used to run a Hartke3500 350w head through my 6x10 cab and was experiencing horrible clipping when I hit low notes.. I was told because I was not pushing enough power through my cab, which led me to pick up my QSC plx1602... On QSC's site, the plx1602 can provide "Continuos average power per channel" of 300w @ 8ohms, and 500w at 4oms. Following the logic of what made me get the plx1602 in the first place, I assume I want MORE than enough power per channel to provide headroom for each cab. Right? Specifically, I'd need at least 800w for the 4x10 and at least 400w for the 18"?

2.) What are the disadvantages or advantages to choosing a 4ohm 4x10 Goliath cab over the 8ohm in a bi-amping scenario? Since my future 4x10 and 1x18 will be getting independant power, I should not need to worry about either of the cabs getting too much or too little as long as I have a power amp with enough headroom. Correct?

I do not get to a computer that often and I'm usually reading this site on mobile, but I am bookmarking this on my iphone right now so and will be checking back frequently. Eager to hear what you all have to say!

Thank you in advance!
 
#585
Gubna said:
check my math:

I can't use two 4 ohm cabinets powered by a GK Backline 600 because that would make them, combined, have 2ohms, and you can't put 4 ohms output into 2 ohms.

correct?

But I could use two 8 ohm cabinets, because that would make, combined, 4 ohms.

I think this is correct, but writing it out helps.
Click to expand...

yes this is correct.
 
#586
lowfreqfreak said:
I would first off just like to thank IvanMike for all of his info on this. I am building a bi-amp system and would appreciate it if someone could help me tie up the loose ends.. (specific questions at the end of my post).

I landed here because I use a 5 string bass and have been running it through an Eden Navigator and a QSC Plx 1602 (bridged to yield 1100w @ 8ohms) through an SWR 6x10 Goliath Sr. (1200w RMS @ 8ohms - from SWR website) for a couple years. Well, the low end (B string) is kinda distorted, not really clean, low thumping bass... "not really kicking ass" in my book. I learned in another thread thanks to Greenboy that my cab simply is not made for faithful reproduction of the low B and when I looked up my cab's specs, sure enough the low frequency range is about 25hz above what I'm looking for.

So I've come to the conclusion that I want to build a bi-amp system with a sub that is rated for 30hz and below. The cabs I'm interested in are the SWR Goliath 4x10 (800w - not sure if I should get 4ohm or 8ohm if they are both rated for 800w), and the SWR Big Ben 1x18 (400w 8ohm).

Ok finally, my questions! :hmm:
1.) In short, I think I'm gonna need a more powerful power amp! I used to run a Hartke3500 350w head through my 6x10 cab and was experiencing horrible clipping when I hit low notes.. I was told because I was not pushing enough power through my cab, which led me to pick up my QSC plx1602... On QSC's site, the plx1602 can provide "Continuos average power per channel" of 300w @ 8ohms, and 500w at 4oms. Following the logic of what made me get the plx1602 in the first place, I assume I want MORE than enough power per channel to provide headroom for each cab. Right? Specifically, I'd need at least 800w for the 4x10 and at least 400w for the 18"?

2.) What are the disadvantages or advantages to choosing a 4ohm 4x10 Goliath cab over the 8ohm in a bi-amping scenario? Since my future 4x10 and 1x18 will be getting independant power, I should not need to worry about either of the cabs getting too much or too little as long as I have a power amp with enough headroom. Correct?

I do not get to a computer that often and I'm usually reading this site on mobile, but I am bookmarking this on my iphone right now so and will be checking back frequently. Eager to hear what you all have to say!

Thank you in advance!
Click to expand...

I think you may want to do further research into bi-amping. Essentially, the 2 cabs you're considering are both "full range" cabs, and hence, not suited for a true biamp set up. What you'll want, is one, very large sub woofer, which will require massive amounts of power, coupled with a crossover, and then a small midrange/tweeter box, maybe a 1x10 or even a 1x8 with tweet, that will require substantially less power. Running 2 full range cabs in a biamp set up is useless. There is lots of info on this site, and google is your freind too. good luck.
 
#589
I just want to thank everyone who has contributed to this thread. I spent a lot of time carefully reading the various discussions (even the heated arguments) and for the first time I feel like I've got an understanding of the basic concepts which will allow me not only to make good purchasing decisions but also will keep me from destroying equipment. Up until this point I can only attribute the fact that I *haven't* blown up an amp to pure luck.

In my playing career I've had several lightbulb moments where all of a sudden something just locks in and makes sense. Most of those moments have centered around my technical playing ability. But I now have had a lightbulb moment when it comes to the electronics behind my sound and that can do nothing but help me. So thank you.
 
#590
i read all through here and some other sites.

I have a 575+575W head, so i wanted to be able to use the max of the power given, so i would work with 2 8ohms cabs.

But, can i, for exemplo, plug both head´s outpup in one 8ohm cab?
and get the same as 2 in paralel:confused::confused:
 
#591
rickkilcher said:
i read all through here and some other sites.

I have a 575+575W head, so i wanted to be able to use the max of the power given, so i would work with 2 8ohms cabs.

But, can i, for exemplo, plug both head´s outpup in one 8ohm cab?
and get the same as 2 in paralel:confused::confused:
Click to expand...

Absolutely NOT. Never plug two amp outputs into the same cabinet. You'll fry one or both of the power amps.
 
#592
this may or may not be the right thread for this question, but i'm running a musicman hd-150 (150w hybrid head) into an old ampeg svt 8x10 (one input jack, no parallel outputs)and i'm looking to add some more bottom end. basically, i wanna know if i can also run my head through a 1x15 without my head exploding. is that even possible??

thanks guys,
- nick
 
#593
youngnicholas said:
this may or may not be the right thread for this question, but i'm running a musicman hd-150 (150w hybrid head) into an old ampeg svt 8x10 (one input jack, no parallel outputs)and i'm looking to add some more bottom end. basically, i wanna know if i can also run my head through a 1x15 without my head exploding. is that even possible??

thanks guys,
- nick
Click to expand...

Not if the MusicMan head is 4 ohms minimum, which I assume it is. Besides, it's a fallacy that a larger speaker will produce more low end.
 
#594
The old MM HD amps are hybrid in a different way than most modern designs: SS preamp/tube output.

There is a switch to select 4 or 8 ohms.

The speaker outs on the amp are wired in SERIES. Running 2x 8 ohm cabs, each from one of the speaker outs = 16 ohms.

Daisy chaining 2x 8 ohm cabs = fine with as long as the switch is set to 4 ohms.
 
#595
wcriley said:
The old MM HD amps are hybrid in a different way than most modern designs: SS preamp/tube output.

There is a switch to select 4 or 8 ohms.

The speaker outs on the amp are wired in SERIES. Running 2x 8 ohm cabs, each from one of the speaker outs = 16 ohms.

Daisy chaining 2x 8 ohm cabs = fine with as long as the switch is set to 4 ohms.
Click to expand...

thanks bud

yeah, i've heard it called a "reverse" hybrid before. i can't daisy chain the 8x10" to a 1x15" because it has literally just one input jack. are you suggesting running my head into the 15" and then chaining it to the 8x10"? or just using both output jacks on the head?
 
#596
youngnicholas said:
thanks bud

yeah, i've heard it called a "reverse" hybrid before. i can't daisy chain the 8x10" to a 1x15" because it has literally just one input jack. are you suggesting running my head into the 15" and then chaining it to the 8x10"? or just using both output jacks on the head?
Click to expand...

If both cabs are 8 ohms: run the amp > 15 > 810. Set the switch to 4 ohms and you'll be good to go.

If you use both output jacks on the amp, you'll have a 16 ohm load. (Assuming both cabs are 8 Ohms.) Not a good load for that amp.
 
#598
Trace Elliott GP7SM130 Head (130W RMS - 250peak) with two 8 ohm outputs in back (which I assume means its min load is 4ohm)

Peavy Mark IV - 800w ( min 2ohm, 400W 2 Ohm or 250 at 4 Ohm)

Cabinets
15" Black widow 8 ohm speaker

810 cabinet (8 32 ohm wired to 4ohm)

THANKS for opinions.
Currently the Trace runs the 810 and the Peavey the 15, the signal is split from a Boss GT-6B Effects Processor (has stereo outputs so one sent to each head)
 
#599
Wow this is a long post and I'm just so confused. Someone posted something close to my situation here in page 4 or 5 I believe.

I'm about to buy a 300 watt @ 8ohms Eminence Legend CB15 bass cabinet.
link here: Invalid Link Removed

The problem isn't if this cab is good or bad, this is what I found in the market at a good price.

Here is my question: I was looking through heads and most of them say 200 watts @ 4ohms or 300 watts @ 4ohms. For example: Invalid Link Removed

What happens if I use the cabinet mentioned before with this head?
What happens if I buy one that has 400 Watts @ 4 ohms?
What is the difference between having more watts in the head than the cabinet or vice-versa?
And lastly: if I were to buy a head with 200 watts @ 4 ohms, does that mean that with a 300 wats @ 8 ohms cabinet I'll get 100 watts only? This is so complicated but I KNOW for sure that it's a better investment than buying a combo amp so I'm giving it my best to try and understand.

Thanks IvanMike for this great post (I really do think I understand a little bit more about this... before I didn't even feel motivated to buy a head & cab because of all the confusion I had but now I feel a little more confident... screw combo amps).


EDIT: I did understand that I can put another 8 ohm cabinet so I can have get full advantage of those 200/300 @ 4ohms head but right now I only have the money and the necessity for 1 cab :P (small sessions at a friends house + some small/medium venue concerts)
 

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