mel taylor wrote on Sun, 19 November 2006 11:35 |
For those of you who are concerned w/ (can hear) sound quality, try a blind comparison w/ any qsc (or new generation crown) vs. any professional concert amp... lab g, camco, dynacord, etc. no doubt that qsc's (sic) are reliable and big bang for the buck, but the fidelity is just not there. you get what you pay for. |
mel taylor wrote on Sun, 19 November 2006 12:35 |
try a blind comparison w/ any qsc (or new generation crown) vs. any professional concert amp... lab g, camco, dynacord, etc. no doubt that qsc's are reliable and big bang for the buck, but the fidelity is just not there. |
Andy Peters wrote on Sun, 19 November 2006 19:09 |
Please describe your test set-up. Show all work. -a |
mel taylor wrote on Sun, 19 November 2006 12:35 |
For those of you who are concerned w/ (can hear) sound quality, try a blind comparison w/ any qsc (or new generation crown) vs. any professional concert amp... lab g, camco, dynacord, etc. no doubt that qsc's are reliable and big bang for the buck, but the fidelity is just not there. you get what you pay for. Mel |
mel taylor wrote on Sun, 19 November 2006 13:35 |
For those of you who are concerned w/ (can hear) sound quality, try a blind comparison w/ any qsc (or new generation crown) vs. any professional concert amp... lab g, camco, dynacord, etc. no doubt that qsc's are reliable and big bang for the buck, but the fidelity is just not there. |
Ken Freeman wrote on Sun, 19 November 2006 22:24 |
Yeah and I like my 40 year old Mac MC 240 way better than all this newfangled transistor stuff....All 40 watts of it! Hey Mel, not buying into the description of your critical listening test. You are going to have to describe your double blind listening test and why you used a speaker processor that I regulary bypass because it sounds like crap. I have hunderds of amplifiers from the likes of Crest, QSC, Crown, BGW, Ramsa, Apogee, UREI, EV, Yamaha, etc. We bench these all the time and rarely find a big difference between any of the majors brands other than output power and how they behave under stress. You are entitled to your opinion, of course, but understand that you will be challenged on your findings when you throw really good products under the bus... Ken |
Geri O wrote on Sun, 19 November 2006 23:45 |
Mel, yours is an opinion that will be shared with next to no one. We have done blind listening tests with the Pls, PLX series and Labs among others. While we are a Lab Gruppen house, we could find no audible differences that we could verify or consistently reproduce. Oh, and by the way, your condescending statement of "those whoe are concerned/can hear sound quality" wreaks of holier-than-thou"-ism. It means nothing in a professional forum. Why can't you just offer an opinion, popular or otherwise, without some little wordbombs such as that? It gets you nowhere. Yes, you are entitled you your opinion, yada yada ad naseum beyond belief-eum (yes, a little gem from the GSS manual) |
mel taylor wrote on Sun, 19 November 2006 12:35 |
For those of you who are concerned w/ (can hear) sound quality, try a blind comparison w/ any qsc (or new generation crown) vs. any professional concert amp... lab g, camco, dynacord, etc. no doubt that qsc's are reliable and big bang for the buck, but the fidelity is just not there. you get what you pay for. Mel |
mel taylor wrote on Sun, 19 November 2006 10:35 |
For those of you who are concerned w/ (can hear) sound quality, try a blind comparison w/ any qsc (or new generation crown) vs. any professional concert amp... lab g, camco, dynacord, etc. no doubt that qsc's are reliable and big bang for the buck, but the fidelity is just not there. you get what you pay for. Mel |
Adam Kane wrote on Mon, 20 November 2006 22:21 |
Mel, Looks like you've got one great set of ears on ya. From my experience, the only times I've ever been able to hear differences between amps (even with cheapies) was when they were driven into oblivion...something I try hard to prevent by properly sizing the amp to the application and the system for the job. I believe JR already mentioned something along these lines so I'll go no further. |
mel taylor wrote on Mon, 20 November 2006 14:43 |
I'm not throwing any products under the bus. Their amps are good, reliable, lot's o' watts to $s, etc. Just like other companies, they have their place. For me, it's just not when you demand the best. |
Bob Lee (QSC) wrote on Mon, 20 November 2006 23:05 |
You are not alone, Mel. I've heard the same sentiment expressed by guys at Guitar Center and the now-defunct Mars Music, but OTOH I don't think those guys know how to compare power amps. Have you ever tried a double-blind test? And I'm serious about the fidelity being in the amps at the factory; the PLX and PowerLight amps in particular would make great studio reference amps if it weren't for their fans. Do you know what went wrong with the ones you tried? |
Quote: |
Whatever happened to frequency response, total harmonic distortion, intermodulation distortion, crossover distortion, etc? No audio device capable of reproducting sound has 0 distortion. Adding qualifiers to statements like "only when used properly" or "out of clipping" says nothing about what happens to an amp when it is ACTUALLY USED. I too could design an amp that has .000000001% THD if it is only required to source 1/400th of its total power. What really matters is what an amplifier does when it is pushed to its absolute limits. For instance, if it is a BASS amp-- it should be run at 100% RMS and 100% duty cycle inside a rack with sagging electrical mains (gotta factor in the 300KW lighting rig on the same service) in 100 degree sunlight in a black amp rack with heavily compressed 50Hz sine waves for 8 hours. |
Tim Duffin wrote on Tue, 21 November 2006 19:38 |
Bob... I can't believe this sentence was actually written by an amplifier engineer: "The PLX and PowerLight amps will really reproduce faithfully what you put into them, up until the point of clipping, so maybe what really displeased you was the input signal." Whatever happened to frequency response, total harmonic distortion, intermodulation distortion, crossover distortion, etc? No audio device capable of reproducting sound has 0 distortion. Adding qualifiers to statements like "only when used properly" or "out of clipping" says nothing about what happens to an amp when it is ACTUALLY USED. I too could design an amp that has .000000001% THD if it is only required to source 1/400th of its total power. What really matters is what an amplifier does when it is pushed to its absolute limits. For instance, if it is a BASS amp-- it should be run at 100% RMS and 100% duty cycle inside a rack with sagging electrical mains (gotta factor in the 300KW lighting rig on the same service) in 100 degree sunlight in a black amp rack with heavily compressed 50Hz sine waves for 8 hours. Then we will know what an amp does after its not on the testbench at the manufacturer under the absolute most favorable conditions that the manufacturer could possibly create. T |
John Roberts {JR} wrote on Wed, 22 November 2006 02:36 | ||
For instance, if it is a BASS amp-- it should be run at 100% RMS and 100% duty cycle inside a rack with sagging electrical mains (gotta factor in the 300KW lighting rig on the same service) in 100 degree sunlight in a black amp rack with heavily compressed 50Hz sine waves for 8 hours. 100% RMS ?? Do you perhaps mean 100% rated power? At which impedance? Which rated power? 100% RMS is what the manufacturer states is the amps RMS--at whichever impedance the manufacturer states GIVES the HIGHEST rated power--and finally the AES standard power rating conventionally used today. (Do I really have to type this, I'm assuming that people reading this have a certain degree of experience in test engineering or at least reading the owners manual) 100% duty cycle.. OK full on, for all the time... Inside a rack ? OK. With sagging electrical mains... Um.. that could be a problem. A typical amp won't put out full rated power if it doesn't have rated mains voltage available. How an amp will act with or w/o a clip limiter turned on will make a huge difference in that situation (clipping). Really... I thought that multi rail amplifiers tended to deal with sagging mains more efficiently than dual rail amps. Sagging mains are a reality-- so why not rate a particular amps performance with that in mind? 100' sunlight. 100' ambient, with a hot rack apparently... BTW, how do you compress a 50 Hz sine wave?? If it was already running at full power applying heavy compression will just turn it down?? Oops, that was a typo-- I was thinking faster than I was typing. I meant either heavily compressed continuous LF or a 50hz sine wave. If a sine wave generator is not available, just play some jungle or bass music to test an amps LF performance--not Van Halen. Incidentally, I agree that there aren't any amps that put out their "rated" power after 8 hours-- I want to know what they do put out after 8 hours straight and call that the "I am actually using this amp in a situation which is not in a lab so what does it actually put out" power. Then, we can compare the "rated" power to the "real" power specs and see which amps live up to their ratings. 8 hours... Now that I understand... 480 minutes... ============== I'm afraid I can't make much sense of your comments. If your point is that amplifiers clip and operate in their nonlinear region when driven hard, I'm inclined to agree. Your ranting makes any real argument extremely difficult to parse out and therefore it is very easy to dismiss the whole screed. If you have a specific point please make it more clearly. JR PS: FWIW I don't know of too many amps that will put out full rated power for 8 hrs continuously. |
Doug Fowler wrote on Tue, 21 November 2006 19:15 |
The chance of you outliving this stigma are about as slim as Miffe getting away from that photo JJJ likes to share. Me, I think it's a damn fine photo and it sort of reminds me of my senior photo in the old high school yearbook. |
Tim Duffin wrote on Tue, 21 November 2006 22:00 |
[ Really... I thought that multi rail amplifiers tended to deal with sagging mains more efficiently than dual rail amps. Sagging mains are a reality-- so why not rate a particular amps performance with that in mind? |
John Roberts {JR} wrote on Mon, 20 November 2006 15:45 |
Most sound professionals knowledgeable about power amps will not be comfortable with your claim that "sound quality" differences are audible in simple listening tests. When listening to a signal chain composed of multiple blocks some of which exhibit much higher levels of nonlinearity, such tests can be compromised by the other weaker links. |
John Roberts {JR} wrote on Mon, 20 November 2006 15:45 |
You may be able to hear differences in amplifier design philosophy wrt to how they handle; clipping (limiters, PS capacitance, etc), minimum load impedances (current and VI limiting), and even design/manufacturing flaws (excessive crossover or class G-H transition perturbations). |
John Roberts {JR} wrote on Mon, 20 November 2006 15:45 |
Sound quality, brings to mind characteristics like linearity (THD and IMD), frequency response, and S/N which will be more similar than different between quality professional amplifiers and difficult to parse out in even double blind listening tests (well maybe not noise floor when the music stops). |
John Roberts {JR} wrote on Mon, 20 November 2006 15:45 |
Perceived differences will more often be caused by simple things like rated or available power. Some designs (like PFC) will be better at extracting power from a given distro so may sound different when pushed hard. There is a place for listening tests to compare how amplifiers act when pushed beyond their rated capabilities, but lets not confuse that with sound quality unless you consider that normal operation. |
John Roberts {JR} wrote on Mon, 20 November 2006 15:45 |
FWIW amp designers invest a great deal of effort to overload as benignly as possible. Such attention to detail is an aspect of product quality, but more like air bags in a car than a sport handling package (sorry to revert to yet another automotive analogy). |
mel taylor wrote on Wed, 22 November 2006 08:24 |
Far from reality JR, ever compare DIM 30(40, 50) tests on a range of pro amps? It's surprising what "pro" amps are terrible at this, or have poorly designed protection circuits that interfere. If this is difficult to hear, even in a blind test, please input pink noise into as many amps as you like, match the outputs, and compare the noise thru a common speaker. Why is there such a difference in the balance of the noise across amplifiers? |
Dave Miller wrote on Wed, 22 November 2006 17:27 |
Have we ever had an amp shootout? |
Ed Walters wrote on Thu, 23 November 2006 10:20 |
Being the guilty party who originally posted about audible differences, and having a reputation re. test benches.... While 1/3 power represents a worst case scenario and 1/8 power is max'ed out rock and roll, IMO an amplifier, if given a power rating by its manufacturer, should be able to deliver that rated power under a steady-state condition sufficiently long enough to measure with a basic test setup of load resistors and a voltmeter. Whenever I test an amp, it's first stop, before I listen to it, is the bench, 1/3 power, for an hour. This tells me its thermal capacity, and if it is going to blow up if I rent it to a DJ, and if the amp is going to meet its published specs, which get checked next. Then I listen. I am known for saying that the Lab Gruppen amps do not meet their published spec at 2 ohms. This doesn't mean they sound bad or don't work in live applications, it means LG should NOT publish an FTC-spec 2-ohm power rating, as the amps cannot deliver to that spec. This is about lies/marketing. It speaks to a corporate mentality that offends me to the point that it does not matter if the amp works, is reliable, sounds good, whatever, I still won't spec them. The rest of the people out there can say they're great/ bla bla bla, but the harsh reality is that LG lies, and this is fact, not opinion, easily verified by any tech. So, to answer your question, live-sound amps never see 100% power in actual use. Does this exempt them from being capable of operating at 100% for a short time? No, not in my opinion. Ed Walters |
Ted Olausson wrote on Thu, 23 November 2006 14:38 |
LAB has a paper that deals with amplifiertesting. http://www.labgruppen.se/media/Testing_Procedure_v1.pdf |
Andy Peters wrote on Wed, 22 November 2006 07:47 |
Dunno where JJJ is right now, so I'll "help" |
Tim Duffin wrote on Wed, 22 November 2006 06:00 |
If a sine wave generator is not available, just play some jungle or bass music to test an amps LF performance--not Van Halen. |
Dave Miller wrote on Thu, 23 November 2006 01:27 |
I'd be very interested to hear if anyone has ever ran an amp at more than 1/3 power other than on a test bench. |
John Roberts {JR} wrote on Wed, 22 November 2006 18:30 |
The slew rate wars ran their course several decades ago and (was it Matti Ottola) the champion of those early unconventional tests to parse out slew induced distortions |
Mikael Holm wrote on Thu, 23 November 2006 20:45 |
Matti Otala, former head of design at Harman/Kardon (at age of 15 he built the first television set in Finland, in year 1954) |
Mikael Holm wrote on Thu, 23 November 2006 20:45 |
I still like my 99.99% pure (digital comparison of output to input using complex music test stimulus). . |
Nathan Lehouillier wrote on Fri, 24 November 2006 02:25 |
Great, So you have us all in suspense. You have a Venice and you are not a fan of cheep QSC's. Please let me know what you use for your best shows. If you tell us B&W's with Krell amps and MIT wire. I will only be amused and truly think you belong with the other morons I am running out of business. Please feel free to put all your money into what ever you want. I will bid against you win and the customer's will never know that your Superior amps weren't there. I think I am going out to get a new QSC tattoo. Nathan Lehouillier Owner Kick Drum Sound & Lighting 1870 Rosewood St. Green Bay Wi 54303 C- 920-471-9072 |
Don Boomer wrote on Fri, 24 November 2006 09:33 |
I like it too ... now who gets to pick the "complex music" and will anyone else go along with it? |
John Roberts {JR} wrote on Fri, 24 November 2006 16:52 |
Thanks for the history. I didn't think he was an engineer. He and several others were pushing these slew related amplifier tests insisting they were a new unknown form of distortion. |