Bill Fitzmaurice

[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.

[quote name='BeLow' post='96550' date='Nov 30 2007, 05:57 AM']I think they link in series rather than parallel whihc theoreticaly might reduce your power output. Maybe some knowlegdeable Nemesis fans will correct me on this?[/quote]The net sensitivity would remain the same, and the increased power handing would potentially allow for more output. However, with series wiring you can't use just any cab. The extension cab would alter the loading of the internal drivers, so anything other than drivers identical to those in the combo would seriously alter tone as well. Series wiring unlike drivers is just a bad idea all around, and should be avoided.

[quote name='AdamWoodBass' post='92951' date='Nov 22 2007, 02:32 PM']Hey guys, like the title says what are the pros and cons of using a small PA for a rig? Does anyone out there just not bother with an amp and go direct? Does anyone use literally a small PA and send a feed to the band PA? Just curious to know what everyone thinks about this?[/quote]
The main disadvantage to small PAs is that they won't handle bass. They're tuned to the vocal range and that's all they'll do well.

[quote name='ashevans09' post='91914' date='Nov 20 2007, 06:34 PM']Hmm, I'd disagree with you on that - my guitarist uses a Kustom 4x12 with his NYC Tech 21 head and it sounds absolutely awesome. However he did pay fair whack for it. Maybe there's a large difference in quality between lower end and higher end kustom cabs?[/quote]
One advantage to being a guitar player is that what we generally abhorr, high levels of speaker distortion, sounds very good with guitar. The most desired amp in the world by guitar players, the '59 Fender Bassman 4x10 combo, is also one of the worst bass rigs ever made. How any companies speakers or amps sound with guitar can't be used as a indicator for how they may work with bass.

[quote name='Jez' post='91756' date='Nov 20 2007, 02:47 PM']Kustom are an american brand, who make guitar and bass amps, and guitars and basses.[/quote]
The only relation between today's Kustom and that which came out of Chanute, Kansas three decades ago is the spelling of the name. It's all Asian now, mostly at the lower midrange of the quality scale. Roughly equivalent to lower end Peavey, for example.

[quote name='crumpet_tramp' post='88874' date='Nov 15 2007, 06:49 AM']Cheers guys hust wanted a quick answer.

I'm gona research into a new cab![/quote]
Before going to extraordinary effort, consider that if your cab was 4 ohms the potential additional output would be only 3dB. In lay terms, that's about the difference between having your volume knob at seven rather than six. If your rig isn't loud enough adding a second identical cab will give you 6dB. If your rig is loud enough it ain't broke, so it don't need fixing.

[quote name='gilmour' post='87891' date='Nov 13 2007, 09:52 AM']
am I right in thinking the Speakon output is for 2 ohms?[/quote]
When a SS amp output is impedance labeled that usually refers to the minimum total load that may be used. As a method of last resort you could consult the manual.

[quote name='bassbloke' post='86953' date='Nov 11 2007, 12:45 PM']You can happily run a transistor amp without a speaker load.[/quote]As you can any direct coupled SS output. No load= no currrent flow. Transformer coupled output stages, tube or SS, must always have a load.