GK 700rb-ii into SWR Megoliath

adamafurious · #1 11-29-2011, 02:12 PM

Hey all!

I'm having trouble running my GK 700rb-ii with my Megoliath. I came on here to search for posts and saw that a lot of you have used and like this combination.

So I was wondering if I might hit you up for some advice.

Basically, we just replaced all 8 of the speakers in the cab, and haven't turned the amp up passed half for a few weeks now (to "break" them in). But it seems that something is wrong because all of a sudden 1 (or maybe more than 1) of the speakers is putting out that awful bass fart sound.

Currently we're running it mono into the top cab and daisy-chaining that into the bottom. As you know, the Mega has this awesome feature but maybe that's wrong for this application? I dunno...I know the amp says 1 4ohm or 2 8ohm cabs, and these are technically 2 4ohm cabs, but does that change when you're daisy-chaining or running mono instead of stereo...etc, etc.

Just wondering how you guys wire yours up. Or if anyone has another idea why this might have happened. Thanks very much. I would definitely appreciate any knowledge anyone might have on this.

dmusic148 · #2 11-29-2011, 02:18 PM

I'm not sure, but CAREFUL- you MAY be presenting your amp with a 2 Ohm load, very bad. Depends on what exactly 'daisy-chaining' means on that cab. If it's a parallel connection vs. series, this is bad (2 Ohm load). But I suspect it's series, unless you changed something.

RickenBoogie · #3 11-29-2011, 03:00 PM

+1 it sounds all wrong. You sure each half is 4 ohms? Were the replacement spkrs modeled for that cab? More details needed to be sure. I've never heard of daisy chaining from one cab into the same cab. Is there no single input to run the whole thing?

adamafurious · #4 11-29-2011, 03:52 PM

Hmmm...that is one possibility we considered.

But I checked SWR's manual and the daisy-chaining we're doing is what they consider running the cabinet mono.

Side note: If you don't know the cab, it has an input into the top 4 and an "Output to Bottom" right next to that. Or you can run each cab separate for stereo.

According to them when you run mono, the whole thing should be 1 4ohm cabinet.

AdamR · #5 11-29-2011, 03:58 PM

I believe its 2 separate 8ohm cabs so running them Daisey changed is 4ohms.

craig.p · #6 11-29-2011, 04:57 PM

1. What exactly do you mean by:

> haven't turned the amp up [past] half

2. Also what are your tone setting on the amp, and on the bass if it's active?

adamafurious · #7 11-29-2011, 08:10 PM

Quote:

Originally Posted by craig.p

1. What exactly do you mean by:

> haven't turned the amp up [past] half

2. Also what are your tone setting on the amp, and on the bass if it's active?

It means I haven't turned the volume up above the halfway point.

All dials at 12 o' clock (EQ, Contour, Presence)

I play a passive bass (Gibson SG) and usually roll the neck pup in or out depending on the song

I experimented with the knobs last night thinking that rolling the bass EQ out might fix it, etc....with no luck.

Also tried hooking up a compressor which helped a bit, but now that the speaker(s) is pretty much "blown", well...

Ben Esparza · #8 11-29-2011, 09:51 PM

Why did you replace the stock speakers? Those SWR cabs (especially if it's pre-Fender) are made to take full advantage of those stock PAS speakers. Why are you "daisy chaining" them. Can't you just run one of the speaker outs from the amp to one cab section and the other speaker out to the other cab section?

I think if you had left the stock speakers in, you wouldn't be having this problem. Just an assumption.

craig.p · #9 11-30-2011, 06:11 AM

Thank you for the additional information.

> It means I haven't turned the volume up above the halfway point.

I was afraid of that. You might be sending far more power to that cab than you realize.

> All dials at 12 o' clock (EQ, Contour, Presence)

Which is about two counties away from "flat."

The SG bass can get very bassy/burpy with that big pickup located so close to the neck heel.

Sounds to me like you were sending an atrociously bass-heavy signal to the cab at a far higher power level than it could withstand.

canadian*eh · #10 11-30-2011, 09:07 AM

Man If you wired Both of the 410 sections to 4Ohms ...Then you can only use that head

with one of them...cause a 2ohm load will fry The head like KFC fries chicken...Nice and

Crispy!! And In the first place why you would ever want to replace the speakers in that

cab unless they were all blown is beyond me....You just cant take any speaker and put it

into any cab and hope it will sound good those speakers are designed to work best with

that cab and by putting something else in there might not work or sound good at all!!!

And yeah it does not matter if you are daisy chaining or just running both cables from

the head 2 4ohm loads will still = 2 ohms... Personally I never daisy chain not even with

my Megoliath unless i only have a head that has one speaker output then that is a

different story!

adamafurious · #11 12-01-2011, 12:52 PM

lol...OK guys...calm down

We replaced the crappy, crusty Fender Chinese speakers with the "good", old ones from SWR (found a licensed place in town that had a stockpile).

I'm sorry I ever put "daisy-chaning" on here...maybe that's confusing. What I mean is: We're running the cab in mono. Why? Because it's a 1200w cab and with a 480w head we're just trying to get as much power out of the head as possible. And at 600w per chamber, it's hard for me to believe that anything I do "tone-wise" would/should even come close to making this cab break a sweat.

Again, I'm sorry if I've misspoke or been confusing earlier in this thread. Please be patient with me. I'm figuring this out as I go

RickenBoogie · #12 12-01-2011, 05:23 PM

But that's just it. The cab's ratings are thermal, meaning actual mechanical limits are HALF that, and then, that's at a certain frequency. The lower you go, the less they'll take- So, pushing 480 watts of sub 100Hz bass tone can literally fry the drivers in a heartbeat. It's so much more complicated than X watts from the amp into a cab rated Y watts.

adamafurious · #13 12-02-2011, 09:15 AM

Quote:

Originally Posted by RickenBoogie

But that's just it. The cab's ratings are thermal, meaning actual mechanical limits are HALF that, and then, that's at a certain frequency. The lower you go, the less they'll take- So, pushing 480 watts of sub 100Hz bass tone can literally fry the drivers in a heartbeat. It's so much more complicated than X watts from the amp into a cab rated Y watts.

Wow...that really sucks...
I'm totally bummed now. But, thanks, as always, for the education.

I guess I'll just use my Mesa Diesel 410 exclusively...It takes anything & everything I throw at it

Ben Esparza · #14 12-02-2011, 10:29 AM

Adam,

You've got a PM.

adamafurious · #15 12-05-2011, 01:18 PM

UPDATE: It wasn't the cab at all...I hooked up my other amp to the Megoliath and it sounded great. No fart-y sound or nuthin'. This amp has virtually the same wattage (if not more) and I ran it through the spectrum of tones. So I've come to the conclusion that either the GK just has a tremendous more amount of output, or there is something internally wrong with the amp itself.

will33 · #16 12-05-2011, 01:35 PM

Quote:

Originally Posted by adamafurious

UPDATE: It wasn't the cab at all...I hooked up my other amp to the Megoliath and it sounded great. No fart-y sound or nuthin'. This amp has virtually the same wattage (if not more) and I ran it through the spectrum of tones. So I've come to the conclusion that either the GK just has a tremendous more amount of output, or there is something internally wrong with the amp itself.

Does the GK work fine on other cabs? If so, try it with the GK again at very low volume. Turn the contour down and keep the boost knob no higher than 9:00 if it was a clock face. Set the 4/5 string switch to 4, even if you play 5. That switch makes an 11db boost @ 20hz.

Check the end of the speaker cable you plug into the amp with a meter, it shouldn't read anything lower than 3. See if it causes the problem at low volume, if not increase volume slowly and see if trouble starts. Keeping the boost knob down keeps the growl effect out of the equation. Forget about the numbers on the volume knob, halfway does not mean half power at all.

mouthmw · #17 12-05-2011, 01:44 PM

See I'm having a similar issue with my 700RB II ever since I switched from Ampeg 810 to GK NEO 412. I get farty distortion on my E string on F, F# and G notes if I dig in really hard. Never really noticed it with Ampeg 810.
It sounds fantastic otherwise, so I just tried raising the strings/lowering pickups to see if that will help. I really hope my speakers aren't having trouble taking what my 700RB II throws at them since I'm not really going nuts on the EQ or volume.
So maybe, try checking your bass setup?

NKUSigEp · #18 12-05-2011, 02:13 PM

Quote:

Originally Posted by adamafurious

lol...OK guys...calm down

We replaced the crappy, crusty Fender Chinese speakers with the "good", old ones from SWR (found a licensed place in town that had a stockpile).

I'm sorry I ever put "daisy-chaning" on here...maybe that's confusing. What I mean is: We're running the cab in mono. Why? Because it's a 1200w cab and with a 480w head we're just trying to get as much power out of the head as possible. And at 600w per chamber, it's hard for me to believe that anything I do "tone-wise" would/should even come close to making this cab break a sweat.

Again, I'm sorry if I've misspoke or been confusing earlier in this thread. Please be patient with me. I'm figuring this out as I go

You've overloaded the power section of the GK by what sounds like inadvertently dropping the impedance down to 2 ohms. Running the cab "in mono" wasn't necessary either. Wattage ratings are deceiving and you really have to listen to what's going on with your speakers - if they're farting out, you're doing something wrong whether pushing them too hard or pushing the amp too hard. I use the 700RB-II to power an Aguilar GS412 and with everything set at high noon and the gain set to around 2:00, I can't go much past high noon on the woofer volume (tweeter volume set to 0) without hearing the speakers just barely starting to break up.

The amp is 480W as you know, and my cab is rated for 1200W as well like yours. What you'll have to pay attention to in the future is the cab's efficiency and cone area. I can move more air with 4x12's than you will with 2x15's and I haven't checked the specs, but I'm willing to bet it's a much more efficient cab and will produce significantly more volume as well.

adamafurious · #19 12-06-2011, 08:33 PM

Good advice!
Thanks guys