Are you using the same watts for the same db level?

[jady]

Lets say you have a 400W amp turned up 3/4 of the way and an 800W amp turned up 3/8 of the way and for discussions sake, they are putting out the same volume. Are you using 300W with both amps or is there a benefit to having the 800W amp except for headroom?

 

[BassIan]

Lets say you have a 400W amp turned up 3/4 of the way and an 800W amp turned up 3/8 of the way and for discussions sake, they are putting out the same volume. Are you using 300W with both amps or is there a benefit to having the 800W amp except for headroom?

The position of the volume knobs is not so directly tied to the power output of any amplifier. The preamp and power amp volume levels (Gain and Master) each adjust the sensitivity of their respective stages. Even at 1/2 on your master volume, it is possible (and with many amps likely) to get to your amplifier's full power. It just takes more signal from the preamp to drive the power amp fully. By turning your volume knob down, you decrease the power amp's sensitivity, which simply makes it HARDER to get full power. But no, there is no linear correlation stating that at 3/4 volume, you're going to get 3/4 of your amp's rated power.

The benefit to having an 800W amp instead of a 300W amp is simply that it will be louder through the same cabinet, assuming you are not wrecking anything. It just won't seem 2.66 times as loud as the 300W amp because of the physics of sound. At best you will see 10log(800/300) = 4.26 dB more volume at peak output. In reality, due to power compression, you will see a lot less. This is a great example of how an increase in cabinet sensitivity can be much more helpful in getting more volume than doubling or tripling amplifier power into the same cabinet.

 

[jady]

Gotcha thanks,

My main reason for asking this is I have a SWR Goliath III 4x10 with a 1x15 Legion cab beneath it. I am powering this with a GK 400RBIII (280W @ 4ohms). I get enough volume, that isnt the issue.

I have been told that for SWR cabs to really bloom, you need to put a bunch of watts through it like with a bigger power amp. Since I dont need more volume or headroom (you can always use more but I dont NEED it) would I actually be using those extra watts at the same volumes? Would it make a difference in sound if I got a 1000W power amp and kept my stage volume at the same level?

 

[BassIan]

Gotcha thanks,

My main reason for asking this is I have a SWR Goliath III 4x10 with a 1x15 Legion cab beneath it. I am powering this with a GK 400RBIII (280W @ 4ohms). I get enough volume, that isnt the issue.

I have been told that for SWR cabs to really bloom, you need to put a bunch of watts through it like with a bigger power amp. Since I dont need more volume or headroom (you can always use more but I dont NEED it) would I actually be using those extra watts at the same volumes? Would it make a difference in sound if I got a 1000W power amp and kept my stage volume at the same level?

For simplicity, assume that with both amps you are using the same TONE as well as volume. To get the same volume from your cabinets, you will use the same amount of power from any amplifier, be it your 280W GK or a 1000W power amp.

The 1000W power amp will allow you to get a bit louder, or to use deeper sub-bass heavy tones that might suck too much power for your 280W GK to keep up with. But, if you're happy with your tone and have enough volume, then stick with what you have. Later on, if you find you need more volume, then you can plan your upgrade smartly knowing that often a more sensitive cabinet can be a more noticeable and effective upgrade than a more powerful amplifier.

 

[Kenny Allyn]

Your so right about the cab sensitivity the old W style cabinets like the Acoustic 360s didn't need 2500 watts to work, but we players kept wanting smaller cabs and watts keep getting cheaper so now we have cabs that will fit in the trunk of car and 1200 watt heads to drive them, plus we DI a signal out now and let the sound guy do his thing.


:scowl: ... Oh and we keep getting older and don't want to carry a big (read heavy) cab anymore...it's a back thing.

 

[Kindness]

Lets say you have a 400W amp turned up 3/4 of the way and an 800W amp turned up 3/8 of the way and for discussions sake, they are putting out the same volume. Are you using 300W with both amps or is there a benefit to having the 800W amp except for headroom?

You've already gotten good advice so this may be superfluous.

If you are operating in the amp's linear range and you don't need more volume or to change your EQ, there is no sonic benefit to the larger amp, assuming all other variables are absolutely equal. The extra power that is not being used doesn't convert itself into a "magic tone supplement." In practice, most amps having different ratings also have other variables. From a practical perspective, if you get the volume and tone you desire out of an amp, there is no need for extra headroom, except as a safety net for when you do need more volume and more drastic EQ. In the end, it all comes down to what you hear. If your amp isn't cutting it (and it raelly is your amp that isn't cutting it and not another variable), you need another amp.

 

[62bass]

Gotcha thanks,

My main reason for asking this is I have a SWR Goliath III 4x10 with a 1x15 Legion cab beneath it. I am powering this with a GK 400RBIII (280W @ 4ohms). I get enough volume, that isnt the issue.

I have been told that for SWR cabs to really bloom, you need to put a bunch of watts through it like with a bigger power amp. Since I dont need more volume or headroom (you can always use more but I dont NEED it) would I actually be using those extra watts at the same volumes? Would it make a difference in sound if I got a 1000W power amp and kept my stage volume at the same level?

I don't want to get into the technical issues here because others are more knowlegable about that than I am. But in your example above, where you are using the GK 400 RB and wonder about the effect on sound if you have more available power, let me give you my example. I used a 400 RB for many years driving a pair of Yorkville 1x15 cabinets. I had lots of headroom and a great sound and only a couple times, on big outdoor stages had the GK up to the point where I was just starting to clip the amp and run out of power. Most of the time everything was fine. Because I found an exceptionally good deal on a GK 2000RB, I sold the 400 and bought the 2000, which would put out 1000 watts into those same 2 cabinets. The sound of the amps was similar in that they were both GK and had very similar preamps and that GK sound. However, the 2000 had just a hint more solidity in the lowest notes and a sort of effertless quality about it. At very high volumes there was no chance of clipping and if I'd pushed the 2000 to its limits which I would never have needed to do, since I could easily have blown the 15s. So, yes, there was a noticeable improvement in sound although not huge. The trade offs were an increase in weight 16 lbs for the 400RB vs 30 lbs for the 2000 and a big difference in price.

I don't know if it takes lots of power for the Goliath to bloom or not. I haven't heard that one. It looks like you've got a good setup now and are running at 4 ohms and getting all the power available from the 400. As long as your amp isn't overhating and sounding very strained, I wouldn't bother changing. I don't know if you were thinking of changing brands or not. If you do, who knows what you'll wind up with, since different brands of amps can be rated at higher wattage yet sound not as loud. If you upgrade and go to the GK2001 RB for your 1000 watts you can expect results similar to mine in my example. Then, if you decide to upgrade speakers at a later date, you'll have no problems driving them.

 

[Richard Lindsey]

I have been told that for SWR cabs to really bloom, you need to put a bunch of watts through it like with a bigger power amp.

I know of no reason to believe that this is anything other than a myth. This implies that the mere hooking up of more watts to the speaker, irrespective of what you play and how loud, magically makes the cab respond differently. This seems dubious at best. My take is that when people think they hear a cab "bloom," they're most likely hearing one of two things:

1. They're hearing the cab differently because they're playing it louder. Your hearing isn't linear, that's why you have such a thing as loudness compensation (google Fletcher-Munson).

OR

2. The amp is sounding better, either because it's a better amp to begin with or, possibly more likely, because with a bigger amp you're not using it so close to the limits of its capacity. Your clip lights may not be telling you absolutely everything that's going on; you may be pushing the smaller amp a bit harder than you think. As a very rough analogy, I used to have a '64 VW Bus. It could do about 65 if there was no headwind, 70 with a tailwind. My current car can do, I dunno, maybe 85 or 90 tops. I could do 55 in either one, but it sure feels better and more responsive to do it in my current car.

My suggestion is that it's not the cab that's doing the blooming; it's not significantly changing how it responds, how it treats a signal. It sounds better when you give it a better signal, that's all. Basically, all cabs do this, within the limits of their capacities. If anything, it's the amp that's blooming when you get a bigger hunk of iron.