Members ShiftChange564 Posted February 4, 2009 Members Share Posted February 4, 2009 I'm interested in the new QSC GX5. It is supposed to put out 500watts/side at 8ohms and only draw 3.3amps at program level. I would use it to power a pair of Yamaha sw118s 300/600/1200. I'm trying to come up with a lightweight system I can use for small gigs and keep the PA under the 15amp load so I can use plain jane 120volt wall power. Just wondered if anyone had any experience or comments on these new amps. I find it hard to believe that an amp like that can be so efficient and put out that much power for less than $400. Is is too good to be true? Link to comment Share on other sites More sharing options...
Members agedhorse Posted February 4, 2009 Members Share Posted February 4, 2009 It's no morte efficient than any of the PLX, PL, CX models. Look at the 1/8-power ratings of the similar powered models and you will see little difference. Note the 1/8-power draw of 3.3 amps is for stereo 8 ohm loads. The 4 ohm rating is 6.3 amps. Provided you don't clip (or limit in the case of the GX series) the amps, this is preatty reasonable. If you drive the amp into limit you will find that the 1/4-power rating is probably more realistic. Link to comment Share on other sites More sharing options...
Members ShiftChange564 Posted February 4, 2009 Author Members Share Posted February 4, 2009 It's no morte efficient than any of the PLX, PL, CX models. I just find it hard to believe it's so much cheaper than the other QSC models that put out similar power. Like what's the catch with this amp? I know it won't do bridge mono or anything like that, but I plan on running it 8ohm stereo anyway. BTW - you guys think this is enough amp for those yamaha 18s? Keep in mind this is for a small system. Link to comment Share on other sites More sharing options...
Members abzurd Posted February 4, 2009 Members Share Posted February 4, 2009 I love QSC and even have respect for their marketing department. It's refreshing that they concede that the amp costs less and many users will actually want to know why that is (as opposed to those that just see a cheap price and buy blindly). In the FAQ article below they explain "how they did it". Sure, it's polished marketing, but also pretty matter of fact with clear explanation of how the amp is designed and the lack of words like "massive" and "awesome" http://www.qscaudio.com/products/amps/gx/gx_faq.htm Link to comment Share on other sites More sharing options...
Members Chip Stewart Posted February 4, 2009 Members Share Posted February 4, 2009 I love QSC and even have respect for their marketing department. It's refreshing that they concede that the amp costs less and many users will actually want to know why that is (as opposed to those that just see a cheap price and buy blindly). In the FAQ article below they explain "how they did it". Sure, it's polished marketing, but also pretty matter of fact with clear explanation of how the amp is designed and the lack of words like "massive" and "awesome"http://www.qscaudio.com/products/amps/gx/gx_faq.htm I'm not sure where the other QSC amps are manufactured, but the GX3 I purchased was manufactured in China. I'm sure that helps keep the cost down as well. Link to comment Share on other sites More sharing options...
Members Norton666 Posted February 4, 2009 Members Share Posted February 4, 2009 We sell quite a few of the GX series amps and we have only had one amp go down. He let the smoke out of it and QSC sent him a new one , no questions asked. QSC is a great company with great products. For the GX amps , they stripped some features ( bridge mode , 2 ohm operation) and outsourced it to China. IMO , they cant be beat for their price. If thats your budget , dont look anywhere else. Link to comment Share on other sites More sharing options...
Members dboomer Posted February 4, 2009 Members Share Posted February 4, 2009 I just find it hard to believe it's so much cheaper than the other QSC models that put out similar power. AFAIK it's based on a new controlling chip that removes hundreds of individual parts ... same one as the new Peavey power amps and probably more to come. Link to comment Share on other sites More sharing options...
Members agedhorse Posted February 4, 2009 Members Share Posted February 4, 2009 A big part of it is the simplified design, simpler (and smaller) sheet metal, and the benefits of experience developed from years of the successful RMX line. Also limiting the external feature set cuts down on expensive parts. Link to comment Share on other sites More sharing options...
Members soul-x Posted February 4, 2009 Members Share Posted February 4, 2009 Also limiting the external feature set cuts down on expensive parts. And support costs, I'd imagine. Link to comment Share on other sites More sharing options...
Members agedhorse Posted February 4, 2009 Members Share Posted February 4, 2009 And support costs, I'd imagine. Yes, especially all the calls about why speakers always blow up when the amp is in bridge mode and it must be an amp problem... Link to comment Share on other sites More sharing options...
Members ShiftChange564 Posted February 4, 2009 Author Members Share Posted February 4, 2009 Thanks for the info, I think I'll be purchasing one of these in the near future. Next question... sort of off topic. I currently have a Crown XLS 602 and soon to be the GX5 in the same rack. I'm going to run both amps in stereo at 8ohms. Do you think I will have any trouble staying under the 15amp load for this to be considered a small rig using a standard 120volt wall power 15-20amp socket? I think the Crown uses something like 6 amps at program levels and GX5 3.3. But as it's been said here before as you approach clip those values increase. Only other things I have in the rack are a mackie cfx12 mixer and 2 behringer gates/comp and a crossover. Link to comment Share on other sites More sharing options...
Members agedhorse Posted February 4, 2009 Members Share Posted February 4, 2009 I wouldn't expect any problems at all. Link to comment Share on other sites More sharing options...
Members SoundMan Posted February 4, 2009 Members Share Posted February 4, 2009 "same one as the new Peavey power amps and probably more to come." I don't think it's the same as ours, it weighs too much. SoundMan Link to comment Share on other sites More sharing options...
Members agedhorse Posted February 4, 2009 Members Share Posted February 4, 2009 I agree, the GX series is "linear" supply (yes, in the non-literal sense of the word) and class AB or H, whereas the (new) Peavey product is SMPS and class D. just about as far apart and can be. Link to comment Share on other sites More sharing options...
Members flanc Posted February 4, 2009 Members Share Posted February 4, 2009 I agree, the GX series is "linear" supply (yes, in the non-literal sense of the word) and class AB or H, whereas the (new) Peavey product is SMPS and class D. just about as far apart and can be. QSC claims the new GX series amps are class B. http://www.qscaudio.com/products/amps/gx/gx_faq.htm The GX3 is a class B amplifier, how does this differ from the more common class AB?The GX3 is a Class B design, as distinct from Class AB. True Class B requires that the positive output stage turn off exactly when the negative stage turns on, and vice versa. If the positive and negative stages overlap, you have Class AB operation, which ensures against any discontinuities, but results in an idle current which creates losses and needs careful bias tracking circuitry. If you have a gap between positive and negative actuation, you actually have "Class C" operation, which is indeed unsuitable for audio due to crossover distortion. Many actual attempts at Class B design end up with Class C results, due to poor understanding of on-off delays, feedback stabilization, and lack of loop gain. In effect, Class B is the exact dividing line between Class C (no idle current, but distorted), and Class AB (idle current assures continuity, at the expense of extra heat). To optimize efficiency and power in a compact chassis, and eliminate problems of bias tracking, the GX series is set up for zero idle current. Careful design techniques and high closed-loop feedback ensure that there is no appreciable crossover gap, qualifying us to claim "true Class B" as an indicator that we combine maximum efficiency with no perceptible distortion. To put this in practical terms, the GX Class B design achieves less crossover distortion than many imitators of our Class AB designs. Bottom line - the GX is "Class B done right".- Pat Quilter Link to comment Share on other sites More sharing options...
Members agedhorse Posted February 4, 2009 Members Share Posted February 4, 2009 QSC claims the new GX series amps are class B. http://www.qscaudio.com/products/amps/gx/gx_faq.htm B or AB, close enough for this discussion. The point was differentiating between linear output stages (AB, B, G & H) and nonlinear output stages (D). Link to comment Share on other sites More sharing options...
Members flanc Posted February 4, 2009 Members Share Posted February 4, 2009 B or AB, close enough for this discussion. The point was differentiating between linear output stages (AB, B, G & H) and nonlinear output stages (D). Gotcha. Not trying to be a smartass...I didn't know that AB and B were close. I have to read the descriptions every time to keep 'em straight. Link to comment Share on other sites More sharing options...
Members frankiefeedback Posted February 5, 2009 Members Share Posted February 5, 2009 The GX3 is a class B amp and the GX5 is a class H. The GX has built in limiting and a 100 hZ crossover that you can use one channel for subs and the other for full range tops. Pretty slick. What tops are you running? I have a GX5 and wouldn't hesitate to buy another. great amp. Link to comment Share on other sites More sharing options...
Members witesol Posted February 5, 2009 Members Share Posted February 5, 2009 i love my gx5, would get another, probably will actually and make a little biamp rig. it's not as sturdy built as even an rmx but for my small local gigs it works well. i also like the various in and output choices. another good amp same price roughly is the yamaha p3500, i've been very happy wityh mine Link to comment Share on other sites More sharing options...
Members zax2000 Posted February 5, 2009 Members Share Posted February 5, 2009 Next question... sort of off topic. I currently have a Crown XLS 602 and soon to be the GX5 in the same rack. I'm going to run both amps in stereo at 8ohms. Do you think I will have any trouble staying under the 15amp load for this to be considered a small rig using a standard 120volt wall power 15-20amp socket? I think the Crown uses something like 6 amps at program levels and GX5 3.3. But as it's been said here before as you approach clip those values increase. Only other things I have in the rack are a mackie cfx12 mixer and 2 behringer gates/comp and a crossover. I would get same brand or different racks ... Crown takes air in the front and vents hot air out the back, Qsc takes air from the back and vents hot air out the front. See where this is going? Might not affect either amp but I like to avoid unneccesary heat if possible ... Link to comment Share on other sites More sharing options...
Members bilbo71070 Posted February 5, 2009 Members Share Posted February 5, 2009 I bought a GX5 when they first came out and had to change the speakon output connector on it. QSC support sent me a new connector and let me change it myself to save the trouble of shipping the it out. Other than that it's been a nice little amp. Link to comment Share on other sites More sharing options...
Members agedhorse Posted February 5, 2009 Members Share Posted February 5, 2009 Take any class B amp and increase the bias slightly and it becomes a class AB amp. Take any B or AB amp and add rail commutators and they become class G/H amps. It's all the same basic topology. Class D is entirely different. Link to comment Share on other sites More sharing options...
Members ShiftChange564 Posted February 5, 2009 Author Members Share Posted February 5, 2009 What tops are you running? I'm planning on running EV sx300s (300/600/1200) However, I'm not planning on using the GX5 crossover capablities for this. I have a dedicated crossover in my rack that I will use with the Crown XLS to drive these speakers. (probably cross around 100-120hz) I'm planning on using the GX5 to power the subs only in 8ohm stereo. Zax: That's a good catch I never would have considered. I probably will be putting it in a separate rack now. Thanks. Link to comment Share on other sites More sharing options...
Members KF650SB1000 Posted February 5, 2009 Members Share Posted February 5, 2009 Last time I checked... I didn't think the GX was a "light weight" amp, since it weights 27/28 lbs. I would call them more of a middle weight amp... they weight more than a PL or PLX but not as heavy as the RMX amps. Link to comment Share on other sites More sharing options...
Members agedhorse Posted February 5, 2009 Members Share Posted February 5, 2009 Yes, it was intended as a compromise regarding power, weight, cost and performance. IMO, it''s a well executed compromise that suits a lot of users. Link to comment Share on other sites More sharing options...
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