masterxela Posted February 9, 2010 Share Posted February 9, 2010 I bought klf-30's a week ago. I like it loud, and the denon sounded stressed, so last week I picked up a qsc gx3 pro amp. Power is awesome, but with sources off and the amp at 1/2 volume, I get an audible hiss/hum from 10 feet. (and I can hear the idle fan on the qsc from 20 feet) So, I've been looking for amps with a (really) high SNR and found the Emotiva UPA-5 @ >119db at 1 watt. I can bi-amp the klf-30's with 4 of the channels on the UPA-5 and should have some serious wattage. Any thoughts on the UPA-5? Any other amps in that price range worth considering? Are there other amp parameters involved with the noise floor? Thanks http://emotiva.com/upa5.shtm Quote Link to comment Share on other sites More sharing options...
artto Posted February 9, 2010 Share Posted February 9, 2010 All I can say is don't be fooled by noise specifications! Case in point: I have some Crown D-60 including the factory performance measurements sheet and the same for Luxman MB3045 tube amps. They are approximately the same power. The Crown solid state SNR measured -116dB while the MB3045 were -98dB. Turn the amps up though and I can clearly hear some hiss from the Crown anywhere in the room. With the Luxmans the noise is barely audible with my ear up to the speaker grill. I'm just saying.....make sure you have a way out [:|] Quote Link to comment Share on other sites More sharing options...
carbon summit Posted February 9, 2010 Share Posted February 9, 2010 I've got the Emotiva XPA-5 and am very happy with it. I've got a KLF-C7 I've been sitting on waitng for some KLF-30 mains to pop up in my area but they never have and you sure can't ship those beasts for cheap! How do you like the rear ports? Is placement an issue? Quote Link to comment Share on other sites More sharing options...
masterxela Posted February 9, 2010 Author Share Posted February 9, 2010 The way my living room is setup (until May) leaves me zero flexibility with placement.(ports 6 inches from wall) After just a few toe-in adjustments, I'd say they're less picky than rf-7's I've had in the same spot, and more picky than kg4.2's I've had in the same spot. Quote Link to comment Share on other sites More sharing options...
stormin Posted February 9, 2010 Share Posted February 9, 2010 I like it loud, and the denon sounded stressed, so last week I picked up a qsc gx3 pro amp. Power is awesome, but with sources off and the amp at 1/2 volume, I get an audible hiss/hum from 10 feet. (and I can hear the idle fan on the qsc from 20 feet) Don't blame it all on QSC. You did happen to grab a bottom feeder. There are alot of nice QSC's up the line. Had a QSC SRA 2422 that was 425 wpc rms @ 8 ohms and you could put your ear down the throat of the horn and not hear a thing. Alot of folks like the QSC PLX 1202 and 1602. The PLX did need a fan replacement to quiet it up. Quote Link to comment Share on other sites More sharing options...
masterxela Posted February 9, 2010 Author Share Posted February 9, 2010 I'm probably giving numbers too much credit. (nearly all qsc/crown amps have SNR spec'd at 100, same as my GX3, which is why I abandoned the pro amp idea) But from reputable companies, you'd hope the specs would be a useful tool in amp shopping. I had the same problem when I tried an xti-2000 on my rf-7's. Noise floor was unbearable. Decided klipsch's are just way more efficient that the speakers those amps were designed for and not a good fit. Quote Link to comment Share on other sites More sharing options...
stormin Posted February 9, 2010 Share Posted February 9, 2010 I'm probably giving numbers too much credit. (nearly all qsc/crown amps have SNR spec'd at 100, same as my GX3, which is why I abandoned the pro amp idea) But from reputable companies, you'd hope the specs would be a useful tool in amp shopping. I had the same problem when I tried an xti-2000 on my rf-7's. Noise floor was unbearable. Decided klipsch's are just way more efficient that the speakers those amps were designed for and not a good fit. Something is a miss. I cant speak for the Xti-2000 or personal expercience with the GX3. My QSC SRA 2422 had a zero noise floor and the Crown K2 I use now has zero . I repeat zero. Its music from blackness. I am not sure what the problem is with your setup or just bad amps or what but pro amps might not do the details and give an air to the music as some of the finer amps and also might have a fan in some of them that make an irratible noise but noway is there a hiss or hum from a good properly functioning pro amp. I'm not suggesting you stick with a pro amp obviously you are looking for something else but again what you are experiencing isn't the norm. Heck Klipsch demoed their high end speakers with a Crown K1. I very much doubt there was humming and hissing going on all over the place. I've had consumer amps that hissed like crazy through my Chorus II's but never the QSC or Crown. Quote Link to comment Share on other sites More sharing options...
masterxela Posted February 10, 2010 Author Share Posted February 10, 2010 Thanks for the info. When I wasn't impressed with the xti-2000 and read that guys were running jubilees off them, it made me wonder... I got a 4000 dollar scholarship today; maybe I'll do khorns+tubes.... Quote Link to comment Share on other sites More sharing options...
michael hurd Posted February 10, 2010 Share Posted February 10, 2010 The noise problem you are having is most definately related to the gain structure of the system. ( hiss ) To prove a point, unplug the inputs to the GX3, and turn on the amp... you should hear zero hiss, even if you stick your head up to the tweeter. Turn the gains down on the QSC and crank up the channel levels in your AV receiver. Re-connect amp inputs ( turn it off first ) and re-test. Quote Link to comment Share on other sites More sharing options...
michael hurd Posted February 10, 2010 Share Posted February 10, 2010 Decided klipsch's are just way more efficient that the speakers those amps were designed for and not a good fit. Nonsense. Pro sound speakers are a lot more efficient than your KLF-30's and regularly get hooked to amps like the GX3 et al. Hum indicates a ground loop, that can be healed as well, an 'isolation' transformer is generally your best bet. Use something like this: http://pro-audio.musiciansfriend.com/product/ART-Dual-TransformerIsolator-Hum-Eliminator?sku=180637 You may find a device like the Rane Balance Buddy / Samson S-convert / Art Cleanbox fixes your hiss issue, if you can't get it fixed with lowering the 'gains' on the GX3 and upping the channel levels in your receiver. Quote Link to comment Share on other sites More sharing options...
jwwrs Posted February 10, 2010 Share Posted February 10, 2010 Thanks for the info. I got a 4000 dollar scholarship today; maybe I'll do khorns+tubes.... Good to know you've got your priorities in good order.[H] Now, go outside and break me off a switch! (If you're over 50 and from the South, you know what that means.) Quote Link to comment Share on other sites More sharing options...
germerikan Posted February 10, 2010 Share Posted February 10, 2010 Im only 42 and from the North but I know what that means!!! Quote Link to comment Share on other sites More sharing options...
jwwrs Posted February 10, 2010 Share Posted February 10, 2010 Im only 42 and from the North but I know what that means!!! Glad to know it wasn't region specific. Nowadays, we'd be in family court. Seemed to have worked on me though. Quote Link to comment Share on other sites More sharing options...
CECAA850 Posted February 10, 2010 Share Posted February 10, 2010 I've got a GX3 and several PLX1104's. The GX3 is quiet, but the 1104's are even quieter. My GX3 is on some very efficient KP250's and hiss is present, but very faint. It may be my gain structure as Michael has eluded to but when music is playing, it's a "mute" point. The 1104's are amazingly good sounding amps, even for critical listening. Quote Link to comment Share on other sites More sharing options...
CECAA850 Posted February 10, 2010 Share Posted February 10, 2010 As far as your fan noise is concerned, a simple and cheap fan swap will take care of that. Quote Link to comment Share on other sites More sharing options...
Coytee Posted February 10, 2010 Share Posted February 10, 2010 Crown K2 I use now has zero Hear! Hear! Another benefit is convection cooled with no fan noise! [Y] Quote Link to comment Share on other sites More sharing options...
SWL Posted February 10, 2010 Share Posted February 10, 2010 Turn the gains down on the QSC and crank up the channel levels in your AV receiver This is what I do with my Crown's and I have zero noise, zero hum/hiss etc. I keep the gains between 9 and 10 o'clock and they're dead silent. I used to keep the gains at 4 o'clock........I learned quickly that turning them down is more beneficial in more ways than one. They go just as loud......without the noise. Quote Link to comment Share on other sites More sharing options...
Don Richard Posted February 10, 2010 Share Posted February 10, 2010 I'm probably giving numbers too much credit. (nearly all qsc/crown amps have SNR spec'd at 100, same as my GX3, which is why I abandoned the pro amp idea) But from reputable companies, you'd hope the specs would be a useful tool in amp shopping. I had the same problem when I tried an xti-2000 on my rf-7's. Noise floor was unbearable. One thing that you have to look for with noise specs is whether they are "A" weighted or not. "A" weighting would give a better number due to HF rolloff. Quote Link to comment Share on other sites More sharing options...
masterxela Posted February 10, 2010 Author Share Posted February 10, 2010 21 in Missouri. No idea what breaking off a switch is.... I've tried playing with the Denon volume level. With the qsc at 9 o'clock, the hiss is perfectly constant with the volume from -74 to +15. At -75 (lowest) it is decreased a little, from +15 to +18 it is slightly higher. I need to have the qsc at the absolute lowest volume setting to not hear hiss at my seat. It is a serious problem on any dynamic music. When I had the xti-2000, I had an art clean box. It bumped up the level fine, but I thought it worsened the noise floor. Maybe my Denon's pre-outs suck? It is DEAD silent with speakers attached, though. I've had 3 electrical engineering courses, and have no worries about replacing a fan, physically. But I feel like I'm buying a $30,000 camry, and spending $20,000 on a supercharger to go drag racing, instead of $50,000 on a Z06. Why not buy a product that was designed for and meets your needs unmolested? (I know fans aren't expensive. It's the jumping through hoops with fans, level adjusters, ridiculous LED's, XLR cables, ugly rackmount tabs... etc) Quote Link to comment Share on other sites More sharing options...
stormin Posted February 10, 2010 Share Posted February 10, 2010 I need to have the qsc at the absolute lowest volume setting to not hear hiss at my seat. It is a serious problem on any dynamic music. Thats a shame. Something is just not right. My Crown K2 I can have the gains maxed and my pre full throttle and not the slightest hiss with my ear at the horns(midrange or tweeter). Hope you get it resolved cause its great when you have dynamics in spades[Y] Quote Link to comment Share on other sites More sharing options...
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