ntrain42
Emo VIPs
Smoke me a kipper, I'll be home before breakfast!
Posts: 2,969
|
Post by ntrain42 on May 30, 2010 16:14:47 GMT -5
WHat your saying is really not the case. WHat Im doing is not stressing the amp out at all. THe UPA-7 is basically 7 indenpendant output boards drawing off a single large power supply. It is designed to run 7 different channels at once. WHen you play say a movie in 7.1, not all channels are being driven by the same load or output level. It varies CONSTANTLY. As long as the amp is being driven within/under its rated output ability and impedance loads it will be fine. See, you didnt read what I stated earlier. If I just run zone 2 BY ITSELF(that means only 2 channels are running on the UPA-7, the other 5 are SHUT OFF)with at most modest levels of power(that means between 2-16 watts continuous at most), cross talk occurs and is audible in the other 5 channels, even though they aren't playing or getting any input signal. Running 2 channels of the UPA-7 is not going to stress that amp out in any way shape or form. THe UPA-7 is designed to run all channels continously with variable impedance loads within its rated output spec. Running just 2 channels at lower power levels is not going to stress out the amp. Running all 7 channels within spec also is not going to stress out the amp. WIth my older Onkyo 906(Which also has a 7 channel internal amp), I can run 2 channels to zone 2, have the other 5 channels off and NOT hear any crosstalk whatsoever. THis is using the same speakers. The crosstalk spec. is significantly better with the Onkyo to the point where there is no audible crosstalk between any channels at any volume level. Man...this is one of those situations where unless you see what your trying to do it's almost impossible to guage your disatisfaction. I think I understand where your coming from with the crosstalk, but does the crosstalk affect the sound when playing your source in two channels at normal volume? Does it bleed through so much that the audio just plain stinks and destroys the imaging, soundstage, and overall sound quality? Have you listened to the amp in surround sound with 5 channels playing and are disatisfied with the whole surround sound experience? Your speaker wire could be acting like an antenna on the long runs. Are you using twisted pairs of reasonable guage (12)? Are you using any rfi shielding whatever? Unless we have an idea of your set-up its hard to tell. Does the crosstalk exist if the amps, source and speakers are closer together in the surround sound set-up? Are your cables somehow touching and causing leakage that way? Sometimes you have to subtract items from the set-up to minimalize all defective possibilities. Cause if the sound sucks with all the components close by and only running one source then you do have a problem and should return the amp as it doesn't meet your requirements. Last but not least there could be a possible design flaw that allows pollution between the power source and each individual amp module? Maybe the five channel amp combined with a two channel amp could be an altogether better solution due to channel over crowding in one 7 channel amp chassis itself. Amps do give off magnetic fields and can do strange things when too close tegether. There might not be enough space between each module inside this chasis to meet your sound quality criteria. The crosstalk between the left and right speakers, isnt what Im having an issue with. I dont use this amp for critical listening, just to power a pair of planars in my workout room, and the 5 channels in my bedroom HT system. THe problem is, when I go downstairs in the morning to workout and turn zone 2 on to play tunes(with zone 1 HT system OFF), my wife gets awoken by the music bleeding through the speakers in our bedroom, all 5 of em. Its audible enough to wake her up. Its not due to the rca cables or speaker cable itself(already checked out this scenario with cable swaps), its the amp itself. Swapping out the UPA amp for the 906's internal amp eliminates the problem 100%. This is just one spec where the UPA is IMO poor. So my solution is to eventually set the bedroom up for 7.1, and buy another amp for zone 2.
|
|
|
Post by gzubeck on May 31, 2010 12:50:19 GMT -5
OK, now all this makes sense...I'm thinking the amplifier modules are just too plain close together in the 7 channel amp. I looked at the pictures and they are almost touching each other. The other funny thing is that human hearing when in a semi sleep state is very acute and sensitive when your other senses are turned off (Eye sight, smelling, tasting etc.). Your brain is just more focussed on hearing and any slight sounds are doubled in impact when resting. So that just adds to the problem. I also wonder that the longer run into another room is not requiring you to crank it up a couple more decibels because of resitance loss, which in turn amplifies the cross talk leakage where the amp is located in the bedroom. I would talk to emotiva and see what they can do for all your troubles. Maybe they could trade for a five channel and a two channel amp at desireable prices. Good Luck! :>)
|
|
ntrain42
Emo VIPs
Smoke me a kipper, I'll be home before breakfast!
Posts: 2,969
|
Post by ntrain42 on May 31, 2010 16:35:17 GMT -5
OK, now all this makes sense...I'm thinking the amplifier modules are just too plain close together in the 7 channel amp. I looked at the pictures and they are almost touching each other. The other funny thing is that human hearing when in a semi sleep state is very acute and sensitive when your other senses are turned off (Eye sight, smelling, tasting etc.). Your brain is just more focussed on hearing and any slight sounds are doubled in impact when resting. So that just adds to the problem. I also wonder that the longer run into another room is not requiring you to crank it up a couple more decibels because of resitance loss, which in turn amplifies the cross talk leakage where the amp is located in the bedroom. I would talk to emotiva and see what they can do for all your troubles. Maybe they could trade for a five channel and a two channel amp at desireable prices. Good Luck! :>) You know, I probably could bug Dan for a swapout, but eventually more blu rays are going to come encoded in 7.1 instead of 5.1(i hope anyway). So Im probably just going to keep it for the time being and just pick up another 2 channel amp. I am going to borrow a friend's XPA-5 though just to see if it has the same problem(run 2 channels to zone 2 and the other 3 channels to the fronts just to see if the crosstalk is any better or worse)exists. If not I may just call up EMotiva again and see if they are willing to work with me on swapping the UPA-7 for an XPA-5 and a pair of UPA-1's. As for the bleedthrough, yeah your senses are more sensitive when asleep, but its loud enough(the crosstalk is variable, the higher I go on the zone 2 volume downstairs, the louder the crosstalk)where just listening to music downstairs at a moderate volume, where you can hear the music clearly through the other 5 channels. The speaker cable runs themselves are less than 25 feet, so that should not be a problem at all. Its just the nature of this amp.
|
|
Animo
Emo VIPs
Gotta Love Me!!
Posts: 2,662
|
Post by Animo on May 31, 2010 20:45:33 GMT -5
Ntrain,
I have absolutely no problems with my XPA-5, and with my 8 ohm main speakers and 4 ohm center and surrounds, paired with my XPA-2, I get 300 watts to all 7 speakers. More than enough power to rattle the foundation!! ;D
|
|
ntrain42
Emo VIPs
Smoke me a kipper, I'll be home before breakfast!
Posts: 2,969
|
Post by ntrain42 on Jun 1, 2010 13:14:10 GMT -5
Ntrain, I have absolutely no problems with my XPA-5, and with my 8 ohm main speakers and 4 ohm center and surrounds, paired with my XPA-2, I get 300 watts to all 7 speakers. More than enough power to rattle the foundation!! ;D Its not about impedance load, but speaker sensitivity differences that can magnify the crosstalk issue. When your in your main HT room listening to 2 channel music you probably cant hear crosstalk in the other channels due to the volume level of the speakers playing in that room along with potentially closer matched speaker sensitivities. When I listen to 2 channel music in my bedroom HT system, I also cant hear any crosstalk in the center or surrounds. But when listening to the second zone downstairs with music (especially with inefficient speakers)and the main zone off, I can, so the question is, is the XPA-5 better at crosstalk reduction over the UPA-7?.
|
|
Animo
Emo VIPs
Gotta Love Me!!
Posts: 2,662
|
Post by Animo on Jun 1, 2010 17:01:13 GMT -5
I know its not about impedance loading, I just added that info because I originally didn't expect to have equal output from the 2 amps going to all my speakers. Also, one of the beautiful things about a 2 channel amp and a 5 channel amp is that I keep the XPA-5 turned off for 2 channel listening. As I only have the one room, I can't relate to your crosstalk situation, other than I understand what your problem is, I just don't have the answers. Again, with that said, I have not had any problems with my XPA amps at all. Hope you can get it figured out because I know how frustrating little nuances and inconveniences can be.
|
|
|
Post by gzubeck on Jun 1, 2010 18:26:56 GMT -5
Not to get off the track too far I wanted to explain the issue with the speaker wire and length and how it affects impedance. If the speakers downstairs are 25 feet away you need a minimum speaker wire gauge of 12 if you drive down to 2 ohm. So if the speakers are of the low ohm kind they will cause problems with long runs. I wanted N train to be aware of this relationship. Link... www.roger-russell.com/wire/wire.htm#wiretable
|
|
ntrain42
Emo VIPs
Smoke me a kipper, I'll be home before breakfast!
Posts: 2,969
|
Post by ntrain42 on Jul 23, 2010 10:52:49 GMT -5
Not to get off the track too far I wanted to explain the issue with the speaker wire and length and how it affects impedance. If the speakers downstairs are 25 feet away you need a minimum speaker wire gauge of 12 if you drive down to 2 ohm. So if the speakers are of the low ohm kind they will cause problems with long runs. I wanted N train to be aware of this relationship. Link... www.roger-russell.com/wire/wire.htm#wiretableIm very aware of impedance loads, the wiring run to the Maggies is 12 guage actually.
|
|
|
Post by gzubeck on Jul 23, 2010 22:37:19 GMT -5
Not to get off the track too far I wanted to explain the issue with the speaker wire and length and how it affects impedance. If the speakers downstairs are 25 feet away you need a minimum speaker wire gauge of 12 if you drive down to 2 ohm. So if the speakers are of the low ohm kind they will cause problems with long runs. I wanted N train to be aware of this relationship. Link... www.roger-russell.com/wire/wire.htm#wiretableIm very aware of impedance loads, the wiring run to the Maggies is 12 guage actually. Ya know whats weird...I'm wondering if these amp are designed to be run all at the same time. The more I hear about the specs they reduce output transistors from say a 2 channel amp to a 5 or seven channel amp. I'm also thinking that the seven channel are so close together inside the chasis that it could be causing a problem. Every post I hear from Emo seems to me that the amps are really not designed to be stressed individually in the multichannel set-up. That means pushing two channels hard on a five or seven channel emo amp is a no no. I've ran across several posts from lonnie on the board. Check out his posts on this topic.
|
|
ntrain42
Emo VIPs
Smoke me a kipper, I'll be home before breakfast!
Posts: 2,969
|
Post by ntrain42 on Jul 24, 2010 18:50:46 GMT -5
THats a possibility, though I really don't run the channels all that hard. Even though the Maggies are 5ohms nominal, they are very low in sensitivity, the UMC-1 needs to be up near 50-55 to get decent volume out of em, and we are talking volume where you can still hold a conversation easily without need to yell or shout. Im thinking there is a 9-12db difference in sensitivity/impedance differences between them and my theater speakers,50 on the Maggies is equal roughly to about 30-35 on the UMC-1 for near equivalent output power. My Kefs are normally run around 1 watt rms at max listening volume Im guesstimating, that would probably equate in output with impedance differences to be about 10-20watts continuous with the Maggies for the same volume level. Thats significant.
|
|