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Bill Fitzmaurice

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Posts posted by Bill Fitzmaurice

  1. Mains should seldom, if ever, be mounted above subs, but that's a PA issue, not electric bass.

    Quote

    Leo got it..... Wrong?!

    Leo was a very skilled machinist, but acoustic engineering wasn't in his wheelhouse. He did recognize the need for tilt back legs on his cabs, though, a feature curiously absent on other brands.

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  2. 3 hours ago, BassAdder27 said:

    I do think a vertical designed cab ( still wide enough for a standard amp head ) has a lot of advantages

    The loudspeaker engineering community has known this since the late 1940s. Neither Leo Fender nor Jim Marshall were loudspeaker engineers, so the blame for poor electric instrument speaker designs that persist to this day can be attributed to them.

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  3. At what frequency to cross over to the subs depends on how low the tops go before dropping off in response and/or output capability. Finding out where that frequency is usually requires experimentation, as it's not a spec provided by most PA manufacturers. 'What other folk are doing' should not be a consideration.

  4. It does not, at least where maximum volume is concerned, which is usually limited by the driver excursion. With no changes to the knobs the four ohm cab will be perhaps 3dB louder. However, all it takes to get the same excursion, and therefore the same output, from the 8 ohm cab is a slight twist of the volume knob. If the amp is rated well below the power rating of the speaker, like by half, then you might, might, get 2 dB higher maximum output from the 4 ohm rig. It might even be slightly audible, but that's it.

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  5. 11 hours ago, MattW said:

     I wish the BB was 4ohms though as it would give me a bit more headroom as a single cab.

    That's a common misconception. You do get higher output per volt, but there's no such thing as a free lunch. You also lose current headroom in the amp. People tend to look at the higher amp power output into 4 ohms as opposed to 8 ohms and assume that's a good thing. It's not, because that higher power output is obtained at the cost of higher current draw.

    • Like 3
  6. 1 hour ago, bassman7755 said:

    I think were both right but just arguing over the semantics of "signal" which to me means voltage and current since to transmit the signal we need some current to flow.

    You can't have the one without the other, but in this case the current level is far too low to be of any consequence and has no influence on the result.

  7. While on the subject: The reason speakers are very inefficient, on average only converting 2% of the electrical energy they receive into sound, is impedance, specifically the impedance of air, which is very low. 8 ohms doesn't sound like it's a high impedance source, but it's a lot higher than air, so nearly all of the energy put into a driver is lost as heat. A horn loaded speaker acts as an acoustical transformer, just like the output transformer in a valve amp. The horn raises the impedance of the air mass that the driver operates into, increasing efficiency as much as tenfold.

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  8. Current doesn't determine the signal level, voltage does. Input impedance doesn't affect the signal voltage flowing in the cable. Losses occur when the amp input impedance is too low, not when it's too high. When the amp input impedance is less than some ten times the output impedance of the bass what's known as loading occurs, which results in signal loss. https://www.electronics-lab.com/article/input-and-output-impedances-of-amplifiers/

    This being the case the higher the source impedance the higher the input impedance must be. Power amps tend to have an input impedance around 10k ohms, because the consoles that plug into them have an output impedance of 600 ohms or less. Instrument amps have an input impedance of 100k ohms or more, because passive pickups have an output impedance of 5k ohms or higher.

     

     

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  9. Even with identical drivers a sealed cab and ported cab will have totally different low frequency response and displacement limited output. You may be able to get a useful result, if you've got the engineering skill to pull it off, but otherwise it's a shot in the dark.

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  10. If they don't have a crossover that assigns different pass bands to different drivers they weren't truly designed to be mixed, advertising claims notwithstanding. I've yet to see definitive objective data that says otherwise.

  11. Like he said. 115s in general don't add any low end to 410s, and they have lower sensitivity and maximum output. That said, where 410s are concerned the Orange OBC isn't exactly stellar, being loaded with entry level Eminence Beta 10 drivers. I'd be looking at replacing it, rather than trying to augment it.

    • Like 6
  12. 2 hours ago, gjones said:

    As a teenager I was told, by the boyfriend of my sister who was a sound engineer, that bass soundwaves take a long distance to form, so you can't hear your bass correctly until you're 20 ft from your cab.

    He may have claimed to be a sound engineer, but he was not. That's the Myth of Wave Propagation, see my previous post above.

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  13. A pair of 210, vertically stacked, is a good option, but IMO the best option involves spending the least, which is the case if you tilt back your 115, perhaps with a touch of lift as well, which you get from a number of stands.

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  14. 6 hours ago, jrixn1 said:
    1. In-ears.
    2. Angled speaker in front of you (either a PA speaker or angled bass cab), since your ears point forwards not backwards.

    Your ears are to either side. They're quite capable of hearing midrange coming from behind you, which is a very good thing in the event that said midrange is the breathing of a Sabre Tooth Tiger. That's not a major concern today, but it was when our hearing evolved to become what it remains. I don't care to have my rig in front of me, if only out of 56 years of habit. It just doesn't feel right. Floor wedges are placed where they are because they have to be to prevent mic feedback.

     

    Where the OP is concerned since the 115 is what you have tilt it back, by whatever means, so that the center of the speaker is aimed more or less at your head. If you need more output then you'd want to stack a second identical 115 on top. As for the 410, it's the worst possible speaker configuration, unless one of the vertical banks of drivers are low passed. AFAIK the Barefaced Four X 10 is the only 410 with that feature.

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  15. It's common for the low end of a 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. This effect gave rise to the myth of wave propagation, that it takes a minimum distance from a source for the bass wave to be heard. But if that was true headphones wouldn't work, nor would car subwoofers.

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  16. The US is having problems with the supply chain of everything from fuel to food for the lack of truck drivers. Many of those laid off during the height of the pandemic moved on to other higher paying jobs. One reason why ships can't off load their containers is the lack of trucks to transport them from the ports.

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