-
Posts
4,424 -
Joined
-
Last visited
Content Type
Profiles
Forums
Events
Shop
Articles
Everything posted by Bill Fitzmaurice
-
That's because stuffing doesn't make the cab look bigger. It lowers the cab Q, which can tame a midbass hump. Making the box larger does that, but making the box larger also lowers the speaker cutoff frequency, stuffing does not. Some 25 years ago a well respected audio expert measured some data and made the conclusion that stuffing made a box act as if it was larger. His conclusion was erroneous, because he didn't measure enough data to reveal what actually occurred. He published his conclusion, and based on his reputation alone much of the professional audio engineering community accepted it at face value without testing to make sure it was true. In both audio and nuclear arms treaties you can trust but you also must verify. 😉
-
Hoffman's Iron Law, to be precise. It's not all that far off from what itu said. On the subject of small drivers they give better midrange dispersion, and can be used in multiples for adequate volume, if they're arranged vertically. When they're not, which is usually the case, you lose their advantage in the midrange dispersion and introduce comb filtering in the highs.
-
For guitar, sure. For bass, probably not. Bass speakers require much larger enclosures than guitar to go low. About the smallest you can go with a twelve for good low end is 60 liters. Their 12B is in the vicinity of 20 liters.
-
That's room modes too, although in the opposite of the usual fashion. The more common result is cancellation of low frequencies on and near the stage when reflections off nearby walls and ceiling meet the original wave front 180 degrees out of phase. When you move away from the stage into the room the relative boundary positions shift, the cancellations cease and the lows return. This phenomenon is what gave rise to the myth of wave propagation, the notion that a wave won't be heard until one is far enough away for the wave to develop. Believers of this myth have no explanation as to how headphones work. 🙄 Whether the bass is too much on stage and not enough out front or the other way around the best solution is to adjust the bass amp for the stage tone and volume and the PA for out front. The problem lies when you don't have PA. I don't know about the UK but in the States it's always been the band's responsibility to provide the PA in most venues. We used to say that we played the gig for free, what we were paid for was providing the sound system.
-
We've got a saying in the States about sphincters and opinions, I've got to assume you have a similar one on your side of the pond. That's especially true of Talk Bass. I had to leave there ten years ago lest I lose what was left of my sanity completely. 😳
- 48 replies
-
- 11
-
-
-
I bought a Bassman 50 watt new, in 1966. Even by the standards of the day it was weak, especially in the lows. Not surprising, as it was a re-badged guitar amp. The 'deep' switch didn't make the tone deeper, it just muted the highs. A 30 watt Ampeg B-15 blew it away on all counts. That's when it began to dawn on me that watts don't mean much.
-
That's the room modes that I mentioned. Parametric is about the only cure for those, and not without cost. They manifest as a product of the positions of the room boundaries, the cab placement and the listener position. Move any one of those three and the result changes, so using a parametric to kill boom where you're standing can kill useful frequencies in the audience. That's why I always adjust my tone from well out front, and whatever that happens to give me on stage I just live with.
-
Isolation devices have no effect, because the boom isn't caused by mechanical conduction between the cab and stage, it's caused by the resonance of the space beneath the floor/stage and room modes. https://www.bassgearmag.com/submit-article-bass-amplifier-isolation/ http://ethanwiner.com/speaker_isolation.htm One potential fix is to lift the cab a meter or so off the floor, which works as an acoustical notch filter. A full parametric EQ works best, allowing you to dial out the boom frequency. If the cause is the stage it tends to be one frequency, as the space below has only one resonant frequency. High pass filters can tame the boom, but they also tame the frequencies below the boom frequency, which tends to be in the 100-200Hz octave.
-
Since you don't hear the pops and clicks through the speaker chances are they're happening in frequencies too high for the speaker to reproduce them. It wouldn't have anything to do with the Class D power amp, as the sends come from before the power amp. You should be able to adjust the EQ on the recording desk channel strip to get rid of those offending frequencies.
-
+1. At the very least it should be tilted back so that you can hear the mids. Yep. Even if one added a BF 2x10 loaded with the same drivers the increase in maximum output would be only 3dB, which isn't worth the bother of hauling the second cab.
-
That's a logical arrangement if the upper driver is high passed and is a driver with specs optimized for a sealed enclosure, perhaps a guitar driver. But there are two other issues with that cab design that make me hesitant to assume how well it's engineered. The port area is too small for a pair of tens, while the horizontally placed tweeters should be splayed inward in a cross-firing arrangement, not splayed outward. That's not to say that it doesn't sound good, but it could probably be better.
-
Even 2x15 mains don't get boundary loading when up on a pole, so what a 2x15 on a pole is capable of with lows a 1x15 on the floor next to a wall will do. The #1 mistake made by PA newbies is tops that at too large, subs that are too small, or non-existent. A pair of 1x10 tops and 2x15 subs is a well balanced system.
-
Outdoors is a challenge due to the lack of walls. Typically it takes twice as many subs to reach the same levels as indoors. Tops don't have that problem as being directional they don't use boundary loading. The subs don't need to be centered, off to the side is fine, but they still should be clustered unless the venue size is so large that they, and the tops, are spread by at least 14 meters or so.
-
Because of the need for boundary loading with bass subs are a must with no backline. I'm not familiar with your subs, but most subs of that sort are pretty much the same. I can't imagine using only one. Don't worry about center clustering, it's not necessary. Just put them together close to a wall wherever they'll fit. Sub output is omni-directional and the wavelengths are too long for them to be directionally located, so they can go anywhere. They don't even need to be aimed into the room. Aiming them at a wall can improve the low end loading and filter out above pass band harmonic distortion that you don't want to hear anyway. I'm not the person to recommend new gear, though. The last time I used speakers not of my own design and making was around 1973.
-
Pay attention to the video with respect to the subs. They should almost never be split left/right. The exception is when they're placed at least two wavelengths apart. At 50Hz two wavelengths is roughly 14 meters. A point the video doesn't touch on is that subs should be placed less than 1/2 wavelength away from the nearest wall for best results. At 100Hz that's 1.7 meters. Having them further out costs sensitivity, and can also result in boundary reflection sourced nulls. Most bands and DJs don't place subs correctly, simply because they don't know any better. It doesn't help when manufacturers show them set up that way, and put pole sockets on top of subs that encourages putting subs exactly where they should not be. When you do that you don't have ground or wall reinforcement for the lows, probably have floor reflection response notches, and may have rear wall reflection response nulls as well. I always have my bass in the PA even though I seldom use subs, but do so only to give dispersion of the mids throughout the room. To that end I high pass the signal into the PA at 150Hz.
-
It's probably no worse than an average 10 on the floor, but on a pole it will be totally different. The lack of ground reinforcement will cost 6dB, the equivalent of a 75% power reduction, while floor bounce cancellation can result in a 24dB response notch. Agreed. It would probably take two 15 inch subs, or one 18, and that only makes sense if the drums are in the PA as well. Not that it's a bad idea to do so, but it's a major expense between on thing and another, while his current rig is a bird in the hand.
-
Those mains are intended to be used with subs to handle the lows, so without subs they probably wouldn't do. Assuming they're up on poles you don't have ground reinforcement,while you do have floor bounce cancellation of bass, which makes the situation even worse.
-
I've seen it before, though I can't recall on what.
-
+1. By and large you want to high pass the bass in the PA around 150-200Hz. That way the directional mids and highs get dispersed throughout the room by the PA, without adding lows that the backline amp will usually provide enough of. The exception would be a very large room.
-
Power has nothing to do with it. What determines cone excursion, which determines sound pressure level, is the amp voltage swing. A SS amp will deliver the same voltage into any impedance load, so when you add a second identical cab both will realize the same excursion. That gives a 6dB increase compared to just one. The halved impedance load results in doubling of the current draw, which results in the doubling of the power draw, but it's the doubling of cone excursion driven with equal voltage that gives the increased SPL.
-
Pickups are like speakers. If they had flat response they'd all sound the same.
-
It comes from amp voicing, which is response adjustments independent of the EQ not user adjustable.
-
Channel strips are designed to have flat response with the knobs at zero, otherwise they'd never pass muster in a studio. Most bass amps are designed to have a pleasing tone with the EQ at zero according to the preferences of the B testers, but with different basses, speakers and personal taste what usually prevails is the preference of the actual designer. An exception is valve amps with the classic Fender tone stack EQ, which not being active is incapable of flat. That was of no concern to Leo Fender. He didn't care what the response looked like, he just wanted it to sound good. The consensus is that he succeeded. https://robrobinette.com/How_The_TMB_Tone_Stack_Works.htm
-
Mixing a 115 and 410 is always a bad idea, no matter what advertising may say to the contrary.