Ive been thinking of trying this. My GAS budget is blown for now so instead of using a crossover could I just use the EQ's on amp 1 & 2 to keep the cabs fom mixing (I can pre-EQ out on my amp 1)?
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How should I bi-amp my Bass Rig?
- Thread starter Pan Dulce Bass
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- bi-amp
Ive been thinking of trying this. My GAS budget is blown for now so instead of using a crossover could I just use the EQ's on amp 1 & 2 to keep the cabs fom mixing (I can pre-EQ out on my amp 1)?
I understand and expect that but what about outdoors - no walls?? or indoors with long buildings (500-600 capacity)? Or smaller venues with drapes for the walls. Every venue I've played since 1970 (hundreds of different venues) has exhibited that same blossoming of bottom end between 20 and ~25-ft. That's why I go out there to do my sound check.
On long buildings, the acoustic coupling is normally really obvious against the back wall, but inside 20-ft of the amp (usually about 10-ft of the stage) is always comparatively weak. So yeah, boundary conditions and whether they are hard and flat or soft and variegated have a lot to do with the sound of a room and will suck out or boost certain frequencies, but it still doesn't explain why all of the vastly different venues exhibit the same blossoming effect of low end between 20 and 25-ft.
Any ideas, because it is just too consistent to be an anomaly???
agedhorse
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No, this is not a good idea, and in addition I would NOT recommend using the XLR out into the 1/4" in on the other amp. Using the eq rather than using a proper crossover is worse than just eliminating the bi-amp thoughts all together and keeping it simple as intended.
The Shuttles are set up signal-wise to use the effects send and return as your routing patch points.
Mine aren't the shuttles but thanks for putting that EQ idea to rest.
Sorry to be stubborn or dumb (or both), but my amp 1 (Markbass Club 450) has a line out pot on the front panel to control the xlr outl and I have an active -10db input on the second amp (yorkville 400 B).
Still too hot a signal?
The best way feed the second amp is with effects out (or tuner out)?
agedhorse
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Sorry, on the phone screen I thought you were the OP.
Between different amps (brand and/or model) you will always need to verify polarity. When a signal routing is used in any way that it was not originally intended, it's possible for the polarity to be reversed.
The answer to your question is "it depends" on your other amp.
First of all, I'm not sure if the 18"s actually get any lower than the 8x10 cab, since both are sealed. Second, the 8x10 will likely be louder than even both 18" cabs, driven full range. If you were separating out the lows from the mids and highs at about 125hz, an 8x10 is total overkill. A guitar 1x12 would probably be sufficient for the mids and highs.
Then how do headphones work?
Even outdoors, any surface, including the floor/ground, will cause some boundary effects.
If it was true that low frequencies have to "develop," then headphones wouldn't work.
Most people have this idea in their head that sound waves are like sine waves through space or waves on a lake. That isnt totally correct, as they are pressure waves. A sine wave might illustrate density distribution, but that kind of amplitude isnt what physically happens as sound waves travel. In a pressure wave all the information needed to interpret it is on the leading edge.
This.
How many of those situations are using PA subs? My bet is all or most of them. These end up acting like multiple point sources, and depending on what boundaries, or lack of them there are, you will end up with some level of interference between the two spatially separated subs, and your amp. up close this interference is pretty concentrated. Unlike the sound coming off of your amp or a single sub, this does "bloom" as the interference propagates away from the source. I would bet that 99% of the phenomena that you attribute to "sound needing distance to develop" is because of this.
Yes. This is a prime counter example.
Boundary cancellations. Quoted in part from BFM:
It's not unusual for the low end of any sub or low frequency speaker to be hard to hear when standing close to it. Reflections off nearby walls and the ceiling create low frequency null zones. If you're standing in one of those null zones the bass will disappear. When you move away from the null zone the true output of the cab will be heard.
Is there any such thing as a long-throw sub? - BillFitzmaurice.info
Actually until about the last 10 years almost no real PA support and certainly no sub-woofers. Back in the early 70's when I was doing the 5-nights a week, 50-weeks a year bit, the PA's were all for vocals and typically you either had a Sure or a Kustom PA. We had a custom though some places we played had the Sure systems. If I recall correctly...this might be wrong...The Sure Vocalmaster had one 10 on top, then three 80's, then another 10 in a vertical column and consisted of two columns and a powered head. Our Kustom had four 12's in vertical columns. Not really any subs on those and none of the instruments or the drums were plugged into it or mic'd. So the instrument sound was not reinforced by an FOH.
I first became aware of the problem of sound blossoming when I was playing a club in 1971 or 72 called the Little Bohemian Club (Little Bo's) in Lincoln Nebraska. It was "the" college hangout and held about 600 people. It was the first night I was using my new Standel amp which was a bit cutting edge design at the time. First it was a Solid State amp and those were just starting to show up, and second it had a very deep cabinet with 4 ports in a vertical array next to two 15" speakers. So it was a tuned and ported cabinet when most cabs were sealed cabs with the exception of the folded horn enclosures that acoustic and Ampeg had at the time. I had turned it up half way and after one song was told by one of the "regulars" that I was burying the rest of the band. So I dropped it down to 9 o'clock and our girl singer went out with her 100-ft cord to walk around and listen as we played. She said it was still plenty loud, but not overbearing. Stage level was pretty low, but if I stood next to it in front of the ports, my bell bottom pants would flap from the pressure out to about 3-ft or so in front of the amp. As long as I stayed within about 20-ft, sound was the same as right in front of the amp. I stepped off the stage with a 30-ft cord one night and experienced a much different sound than I did on stage. I've always done my part of the sound checks out front ever since.
Your explanation makes sense with current PA set-ups and interference and or lack thereof. Though usually, the PA FOH speakers are in front of the stage or at least in front of us when we are playing. We'll have monitors facing us but that would be about the only interference on stage. Still the rest of it makes sense.
Thanks for taking the time.
Probably true about the headphones, but headphones are not using a direct radiator in an open space where pressure has to be built up to project the sound. Presuming you are using either over-ear headphones or in-ear ear-buds, that's a sealed close space where the pressure is going to be heard and felt immediately because the radiator doesn't have to build up a pressure level. Heck on some headphones, they use bone conduction to augment the bass. So that's an apple and oranges comparison.
Still the thought of it being a pressure wave that responds to other pressure waves with cancellation and reinforcement zones makes a lot of sense to me.
agedhorse
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Don't forget that the immediacy of the pressure wave is based on the speed of sound, so at 20', we are talking <20mSec.
And pressure drops with the square of the distance.
Meant as supplement,
In any room acoustic situation that can cause "null zone" dead spots means that there are as well "hot spots" with +6dB excessive increase of level. Of course all these "spots" are frequency depndent but very nasty for sure, these are the so called room modes.
I was just browsing through and ran across this thread. Just a couple of points I'd make on bi-amping (or tri-amping):
1) The reason for doing it is to avoid the loss of power in a passive crossover, which can be significant. A -3db insertion loss, for example, is half your amp power (although that would be a particularly crappy passive crossover).That not-lost power then goes to the driver instead, meaning you need less total amp watts to get the same SPL out of all your speakers, thus retaining more headroom >> clarity. OK, maybe that's "sterile", but I'm of the school that tone should be shaped in your pre-amp/amp, not your cabinet.
2) An individual speaker might actually be capable of more loudness when bi-amped, compared to full-range. If you limit the bandwidth it has to reproduce, you can run a higher voltage to it before reaching its RMS power dissipation limit (assuming the speaker is within its excursion limits). That's louder (in its limited range).
3) Bi-amping is not so equipment-intensive as it used to be, with crossovers now built into many power amps; and Speakon cables can be configured to carry two channels. Not all that complicated.
Let's not throw out the baby with the bathwater. Bi-amping is an attractive option if you design it into a system from the start; or even as a modification to an existing system that has a passive crossover.
1) The reason for doing it is to avoid the loss of power in a passive crossover, which can be significant. A -3db insertion loss, for example, is half your amp power (although that would be a particularly crappy passive crossover).That not-lost power then goes to the driver instead, meaning you need less total amp watts to get the same SPL out of all your speakers, thus retaining more headroom >> clarity. OK, maybe that's "sterile", but I'm of the school that tone should be shaped in your pre-amp/amp, not your cabinet.
2) An individual speaker might actually be capable of more loudness when bi-amped, compared to full-range. If you limit the bandwidth it has to reproduce, you can run a higher voltage to it before reaching its RMS power dissipation limit (assuming the speaker is within its excursion limits). That's louder (in its limited range).
3) Bi-amping is not so equipment-intensive as it used to be, with crossovers now built into many power amps; and Speakon cables can be configured to carry two channels. Not all that complicated.
Let's not throw out the baby with the bathwater. Bi-amping is an attractive option if you design it into a system from the start; or even as a modification to an existing system that has a passive crossover.