Rickresource Rickenbacker Forum

Hi All: I have a Gallien-Krueger 700RB-II. Right now I'm running it through a GK 4x10 @ 8 ohms, so the 700RB is pushing 320W. I'm trying to get the most I can from the amp, and my speaker cab is pretty old, so I may replace it in the near future. So here's one of my main questions:

If I add a second 4x10 @ 8 ohms and run the two of them in parallel, the impedence is reduced to 4 ohms, and the 700RB pushes 480W. Problem is, as I see it, that's 240W to each of the two cabinets. So what are pros and cons of the two set-ups in terms of overall volume and "bigness?"

To re-cap: One 4x10 at 320W or two 4x10s at a total of 480W (240W to each cab).

Another option would be to find a single 4x10 that runs at 4 ohms. Any other suggestions (I prefer 10's, but would consider a 1x15)? GK has a NEO 4x10 that their website touts as being either 4 or 8 ohms, but every vendor lists it as 8 ohms.

Now, another related question: I've heard a lot about headroom and speaker ratings and amp wattage. In other words, should the amp wattage always be less than the speaker cab rating? Is it better to have both wattage and speaker wattage rating be close to one another? The above example illustrates ahow my speaker cabs could be subjected to 240W or 320W.

Much thanks!

John

Hi John,

The power/volume is easy maths so I think I can help.

Doubling amp power will produce a mere 3db increase in volume (all other things being equal). To put this in perspective, the human ear perceives a 10db increase in volume as a doubling in volume. The formula for volume gain is G = 10xlog(P2/P1) where P2 and P1 are the repective power ratings of your amp indifferent configurations and log is the base 10 logarithm function. Thus, your jump from 320 watts to 480 watts will probably increase volume by around 1.76db, which will be audible but hardly gut-crunching.

On tone - lowering the power load to the speakers will theoretically reduce the incidence (or likelihood) of distortion, assuming the second cabinet has the same rating as your present one, so you should get a cleaner sound with more "headroom". Beyond that it gets subjective, and will hinge on the configuration of your additional cab (eg 4x10 v 2x12 v 1x15, cabinet materials and design) and quality of speakers and your (or your band's or audience's) subjective tonal preference more than anything else.

Thanks for the reply Evan. Of course there are always more questions!

What I understand from your post, if I add a second (let's say identical for now) cabinet, I will increase the overall wattage and get a modest increase in overall volume, even though the wattage to each cabinet will effectively be reduced from 320W to one cab to 240 to each of two cabs. The benefit there is that the potential for clipping and "unwanted" distortion should be reduced somewhat.

I say "unwanted," because I like a fair bit of mid-range growl and overdrive. I'm assuming that is differnet from the distortion you mentioned.

If I took another option and bought a 4 ohm 4x10 (any recommendations?) that is rated well above the 480W my amp puts out (say a cab rated @ 800W), would the 480W amp be enough to drive it properly?

FretlessOnly wrote:Thanks for the reply Evan. Of course there are always more questions!

What I understand from your post, if I add a second (let's say identical for now) cabinet, I will increase the overall wattage and get a modest increase in overall volume, even though the wattage to each cabinet will effectively be reduced from 320W to one cab to 240 to each of two cabs. The benefit there is that the potential for clipping and "unwanted" distortion should be reduced somewhat.

I say "unwanted," because I like a fair bit of mid-range growl and overdrive. I'm assuming that is differnet from the distortion you mentioned.

That is indeed what I intended to mean - I believe it is the "unwanted" distortion you are avoiding - the grind you get from amp break-up or a pedal will remain.

FretlessOnly wrote:If I took another option and bought a 4 ohm 4x10 (any recommendations?) that is rated well above the 480W my amp puts out (say a cab rated @ 800W), would the 480W amp be enough to drive it properly?

Unfortunately I haven't got any 4x10 recommendations - I'm using 1x15 Ashdown cab with my Vox AC50 as my favoured set-up at the moment, with an SWR 2x10 combo and a GK microbass 1x12 combo as my alternatives, which are all way downstream powerwise from your kind of rig. Apologies!

I do note, however, that your amp will have no issues driving higher rated speakers.