Bill Fitzmaurice

[quote name='Hamster' post='113329' date='Jan 3 2008, 08:51 PM']IIRC, it's twice as loud as a speaker of 103db sensitivity if using the same input level. I may be wrong, but I think I'm right. No doubt Bill F or Alex C will be along soon to put me right Hamster[/quote]Close. A 3dB difference is equal to twice/half the power, but not twice/half the perceived volume. Hearing response is logarithmic, so it takes a 10dB difference to sound twice/half as loud. As for manufacturers SPL ratings, they're next to useless, because they aren't referenced to frequency. Some, like Ampeg, quote a legitimate average figure. Some, like Eden, quote a peak figure. Some quote figures that defy all known laws of physics. None save Phil Jones provide the all important SPL charts that allow one to know the facts.

[quote name='jamjarjay' post='111271' date='Dec 30 2007, 08:50 PM']how can I tell I'm running too hard without damaging my head? Thanks, JJJ[/quote] Clipping can't damage a head. But a clipped waveform greatly increases the high-frequency content of the signal, and that can lead to overpowering and possibly damaging tweeters. If you don't have tweeters don't worry about it.

[quote name='umph' post='110319' date='Dec 28 2007, 03:00 PM']if its ported you'd probly want the port on the floor so you get more low end. you can always put it in a corner to make it louder to.[/quote] No difference. A port's output is roughly from 40 to 80 Hz, and is omnidirectional. If it's within less than a quarter wavelength of a boundary it gets boundary reinforcement. A quarter wavelength at 80 Hz is 3.5 feet. [quote]There has been a tendency for some time now for hi-fi cabinets and multi-channel sound systems to follow this path. You don't see many cabs that don't try to keep a fairly narrow front face, making up internal volume with back to front depth as well as height. A narrow front face apparently helps to give a better stereo image when using two cabinets and helps the perceived location of sound in a room if using more than two in a multi-channel set-up. Even lateral dispersion is one of the factors affecting how well a pair of speakers create a believable stereo image.[/quote] That all has to do with diffraction, which is a different matter entirely. [quote]Some say that rounding off the edges of cabinets helps as well, but whether this would have any useful purpose on a bass cab is debatable.[/quote]Also a diffraction issue, and less than about a 2 inch radius has little to no effect.

[quote name='bass_ferret' post='108993' date='Dec 24 2007, 12:13 PM']I wonder how this baby will sound? [/quote] On the technical side, it's a bass reflex cab, like 90% of the cabs on the maket, loaded with Eminence dirvers, like 90% of the cabs on the market. But it does have the drivers vertically aligned the way they should be, not horizontal like 90% of the cabs on the market, so it's a step in the right direction. If it only had a midrange driver instead of a tweeter, so there would not be a midrange 'hole' in the response, and if the box were actually large enough to allow the woofers to work as well as they could, I'd call it a proper design.

[quote name='Hamster' post='108895' date='Dec 24 2007, 07:51 AM']IIRC, the argument is that it's always best to stack speakers vertically. It improves the vertical dispersion - which I can get my head around, and for some reason it improves the wider dispersion - which I don't understand I'm trusting the opinion of someone like Bill Fitzmaurice or Alex Claber on this. Hamster[/quote]Two reasons for vertical stacking. One, you can hear them better. Two, the audience can hear them better. That has to do with two other facts. First, the all important midrange frequencies travel in relatively straight lines. The further the speakers are below your ear level the more difficult it is to hear them. Second, the angles of dispersion are inversely proportional to the width and height of the source. A low wide source has narrow dispersion on the horizontal plane, wide dispersion on the vertical plane, and that's the precise opposite of what's desired. Wide horizontal dispersion, for the benefit of the audience, and narrow vertical dispersion, so as not to waste power scerenading spiders on the ceiling and mites on the floor, is what you want, and you get that from a source that is narrow and high. [quote]TBH you aren't talking HUGE difference when you do this.[/quote] Not necessary with one 2x10, but two stacked on end one over the other is significantly different than two side by side on the floor. That's why side by side cluster PA systems are landfill bound, being replaced by tall line arrays. Bass cabs should be tall and narrow too, but technologically the electric bass cab industry lags the PA industry by at least a decade, if not two.

[quote name='TimmyC' post='108048' date='Dec 22 2007, 06:23 AM']I thought he used an Ampeg B15n for a lot too?[/quote]For monitoring, his recorded sound was taken direct. The purpose of tweeters is to allow the full range of the bass to be reproduced. As noted previously the main defect usually lies in the implementation, not the device. Most bass cabs would be far better served using a midrange driver in lieu of or in addition to a tweeter, the main reason why they aren't is cost, pure and simple.

IMO combos are almost valueless. Where portability is concerned sticking the head and speaker in the same box just makes for a heavier box. Where sound is concerned, in the effort to keep the overall box size and weight manageable they're even worse than separates vis-a-vis using too small a cab for the drivers within. As for flexibility, I'd rather a separate head and well engineered cabs, using as many or as few cabs as the gig requires so that I'm neither lugging too much gear to a small gig nor under-gunned at a large one. The only combo I'd consider is for personal practice, where output and tone aren't a consideration.

[quote name='jammie17' post='104520' date='Dec 14 2007, 04:38 PM']McIntosh ARE professional power amps, Gratefull Dead toured with them for years and they are used for pa amplification....[/quote] McIntosh makes great gear, but they have always been a high-fidelity company, never pro-sound in the vein of Crown, Crest, QSC, etc. Decades ago they were often employed in pro-sound applications, but that's because at that time all amps were hi-fi and theatrical gear drafted into pro use. While one could use current McIntosh offerings in pro-sound applications, it's not their focus and they don't specifically market their products for pro-sound usage. So doing allows them to use features like autoformers in home and studio applications where the resulting extra weight and chassis size is not a concern. But you won't find an autoformer in an amp made for the pro-touring sound market.

[quote name='jammie17' post='104467' date='Dec 14 2007, 02:32 PM']Ahhh, you see I did not know that about them. So, an an amplifier that has say, three different outputs...say 2,4,8, ohms, has three Autoformers?[/quote] A tube amp doesn't have any. Tube amps use multiple tap secondary transformers. A transistor amp can use a single autoformer with multple taps, but no professional amps I know of do, it's an unnecessary expense and adds weight as well as cost.

[quote name='jammie17' post='104392' date='Dec 14 2007, 12:03 PM']The Autoformer creates an ideal match between the power amplifier output stage and the loudspeaker.[/quote]Autoformers are nothing new, they've been used for decades. They're only necessary if the impedance load is lower than the output stage can handle in a normal direct coupled configuration. While acting like transformers they have only one winding, so they are not preferred for use in audio, as there is no separation between a primary and secondary. Their advantage is that since they have only one winding they are cheaper to produce than a transformer.

[quote name='jammie17' post='104359' date='Dec 14 2007, 11:11 AM']Don't want to argue. Mc'Intosh uses output transformers called, "audioformers" with s/s power amps.[/quote]Once upon a time, before the invention of transistors capable of being direct coupled, all SS amps used output transformers. For the last 40 odd years direct coupled outputs have been preferred.

[quote name='jammie17' post='104039' date='Dec 13 2007, 03:01 PM']Ahh..thank you Bill...I did mis-state. Let me re-state. 300 watt amp with multipal taps on it. 2, 4, 8. Amplifier is claimed to deliver 300 watts into evey load, however, if you hook up the same load, say, 4 ohms, to the different taps, you get three different volume levels. Why? Three different Voltages delivered at those different outputs. Voltage = volume...so in the ohms law it would be best to have more voltage with less current....but then speaker control would suffer.[/quote] Irrespective of the tap used if you don't change the impedance of the load. ie., the speaker, then you are not changing the output voltage of the amp if the same power output is maintained. What you are changing by using a different tap is the number of turns on the secondary of the output transformer being utilized, and yes, that will alter the volume level, because it changes the output voltage available. But it does not alter the current available, that is a constant with a tube amp, so if the volume goes down it is because the voltage swing is also down. Doing so is also begging for trouble, as an impedance mismatch between the output transformer and speaker can fry everything from the output transformer to the output tubes to the input transformer, and everything in between. Most amps are built to withstand abuse of this sort, but many have found out the hard way that amps will only take so much.

[quote name='Peaty' post='103920' date='Dec 13 2007, 10:36 AM']Hi All, yup, I took it out of the cabinet and the speaker had no info on it what so ever, hence my question.[/quote] Confucius say "picture worth thousand words".

[quote name='jammie17' post='103682' date='Dec 12 2007, 09:16 PM']Well, that's not necessarily true. 300 watts with a lot of current vs voltage, or 300 watts with a lot of voltage vs current. [/quote] It's always true. Ohm's Law. For a given wattage in order to alter either the current or voltage one must also alter the load impedance. For instance, 300 watts into 4 ohms is 34.6 volts at 8.7 amperes, period.

[quote name='carlosfandango' post='102945' date='Dec 11 2007, 05:04 PM']Hmmmm that sounds interesting.....how does this work? Do you mean like you would use a compressor/limiter e.g when mastering a recording or in modern PA systems to create a "louder" mix?[/quote]That's pretty much it. The power output of an amp is limited by its voltage swing. Compression allows one to increase the density of the signal within a given voltage swing, therefore sounding louder without actually being louder. The one thing that sets valves apart is that they can compress the signal in both the pre-amp and output stage, while SS can only do so in the pre-amp, so while valve sound can be emulated it can't quite be duplicated.

[quote name='NJW' post='103569' date='Dec 12 2007, 04:13 PM']Everytime he hit the distortion, lots of light. Hmm...[/quote]Distortion boosts the high frequency power content, and that would cause the tweeter protect lamp to light up brighter than otherwise. Low frequencies won't light it up. To test this, turn the high EQ all the way off, the light will dim. BTW, the increased HF content caused by distortion can fry a tweeter in a heartbeat, so if you use distortion turn the tweeter down.

[quote name='Peaty' post='103241' date='Dec 12 2007, 09:02 AM']Hello folks, Does any one know who actually makes the speakers in EBS Evolution NeoLine Pro cabinets. Is it EBS or do they source them from another manufacturer? cheers Peter[/quote] You tell us. Take the driver out and look at it. AFAIK only Eden makes their own drivers, and even then only the older ceramic magnets.

[quote name='RIM Basses' post='102939' date='Dec 11 2007, 04:54 PM']When I had my mesa 400+ at full power, I was told that to get the same power out of a solid state rig you would need around 1600w So basicly tube amps are four times louder? Ive been playing a Thunderfunk 550B and I dont really miss the Mesa anymore. Cheers, Robbie[/quote] Tube amps have natural soft-knee compression. 6dB of compression can make the amp seem to be four times as powerful. You don't actually need four times as much SS power, but you do need a properly set high quality compressor.

[quote name='steve-soar' post='102451' date='Dec 10 2007, 05:48 PM']Failing that, buy a big amp and an even bigger cab, cabs! Cheers Steve.[/quote] Threaten them with this possiblility, they will fall in line.

[quote name='DrGonzo' post='101821' date='Dec 9 2007, 01:20 PM']At least, from where I'm standing that seems to be the reason. Either that or I'm talking sh*t, and I'm sure someone will point that out![/quote] Pointed. Distorted signals have excess high frequency power content that can toast tweeters, so hi-fi and PA systems need plenty of amp headroom to minimize the possiblility of distortion. Instrument speakers are designed to handle distorted signals so amp headroom is not a requirement; where guitar is concerned it can be detrimental to tone. Bass cab tweeters can have problems with distorted signals if they aren't robust enough to handle distorted signals, but most are designed to do so.

Make sure that the compression you're getting is within the amp and not the speakers. The average ten in an average cab will only take about 50 watts before it reaches xmax in the 60-100 Hz power bandwidth, so getting an amp that will give them even more may not make any difference.

[quote name='steve' post='101475' date='Dec 8 2007, 02:10 PM']@ gypsymoth and bill so are you saying in your respective (and respected) opinions,that I haven't got enough headroom with the Hartkes?[/quote] The average cab won't take more than 1/2 its rated power before exceeding xmax, and many won't even take that much. Having more is not going to make things any louder. It won't hurt, but it isn't a necessity. There's a very simple way to know if your amp/speakers have adequate power. Are they loud enough? If so, they do.

[quote name='gypsymoth' post='101445' date='Dec 8 2007, 12:34 PM']I think that article is quite misleading on a number of levels -[/quote] +1. It verges on a retelling of the Myth of Underpowering. Some valid points are raised as far as hi-fi and PA are concerned, but pretty irrelevent with regard to instrument amps.

[quote name='nottswarwick' post='97160' date='Dec 1 2007, 06:42 AM']Interesting. Why do so many off the shelf cabs have them horizontally aligned?[/quote] They look better that way.

Two tens vertically aligned offer wider horizontal and narrower vertical dispersion than one twelve. BTW, since the obverse is also the case drivers should never be horizontally aligned.