XPA-5 noise floor. XLR help?

[JasonJCarney]

There have been quite a few posts about the noise floor on the XPA-5, especially when using a highly efficient speaker. I have said problem with my RF7ii's. It's only noticable when there is no contant playing. I am currently using RCA cables. Would changing to XLR cables make a difference?

[CECAA850]

There have been quite a few posts about the noise floor on the XPA-5, especially when using a highly efficient speaker. I have said problem with my RF7ii's. It's only noticable when there is no contant playing. I am currently using RCA cables. Would changing to XLR cables make a difference?

Possibly if the noise originated from the RCA cables themselves picking up noise (doubtful in this scenario though).

[Gorm]

I get the noise on mine only if I turn the amp on before the receiver. After the receiver is on, the noise goes away.

[SuBXeRo]

i tried rca to xlr and it actually got more noisy as far as static in the horn goes. I have really come to the conclusion that the high gain on the emo amps is detrimental to high sensitivity speakers and that the noise floor is low otherwise. I have bought all new rca's and i am waiting for my outlaw amp to come in and test. I have gotten all 3 foot rca's in hopes of eliminating any ground loops within the rca's themselves. I have also ready that XLR's can increase the gain which would be taking things opposite of where it appears u want to go.

Ill let you kno my findings.

[Fish]

See next post, what's up with this site lately?

[Fish]

My UMC and LPA7 is the quietest multi ch set I ever owned.That's saying something for 7's which until this set was never deathly silent.Is there noise with just the amp only on?

[JasonJCarney]

Not sure about those questions. I'll play with it Tuesday or Wednesday and figure that out. yeah Sub let me know what you find.

[SuBXeRo]

i tried some knukonceptz wires, i have wanted to try their stuff in the past for my car but wound up using stuff for HT. They arrived today and i unwrapped them all. The quality is....well, decent. I think there are a few places that can be improved upon like the jacket pants section is very flimsy and the interior of some of the connectors, depending on type are plastic with a metal shell that screws onto it. BUT, they contain a few forms of shielding.

this is just an example of one of the types of cords i bought.
http://www.knukonceptz.com/productDetail.cfm?prodID=KRY2.1M

[russ69]

I don't think the Emotiva amps are the quietest amps on the market and the RF-7s are not making the situation any better. You have to be very careful when mating high gain amps to high-efficiency speakers. If the problem is solely with the amp, you are cooked but if it's due to the pre-amp raising the noise floor an attenuator will work.

[Greg Oshiro]

<snip>If the problem is solely with the amp, you are cooked but if it's due to the pre-amp raising the noise floor an attenuator will work.

Hear, Hear!

For the OP: If you're handy with a soldering iron, try this:

1. Build an RCA shorting plug. Solder the tip to the sleeve of an RCA plug. You might need a short length of bare wire, but usually you can bend the sleeve terminal enough to do this.
2. Turn off the amp. Wait awhile, say a minute.
3. Disconnect the cable from the amp input.
4. Connect the shorting plug to the amp input.
5. Turn the amp on.
6. Is the amp sufficiently quiet? If not, The problem is in the amp. Could be a noisy amp or interference of some kind. Otherwise try an attenuator.

I'm running Khorns. My amps have 26 dB of gain. I have passive switched attenuators before the amps that are usually set at -30 dB. That means the gain from my electronic crossover to the speaker terminals is actually(-30 + 26 = -4) dB. *That's 4 dB of loss*. But the crossover also can put out about 20 dB more than a "typical hi-fi preamp". So let's say a "typical hi-fi preamp" would then need a power amp with (-4 + 20= +16) dB of gain to drive the Khorns to the same level. The Emotiva XPA-5 has a gain of 32 dB, if I read the specs correctly. That means my rig would need a 16 dB attenuator between the "typical hi-fi preamp" and an XPA-5. I don't know what's on the market, but I'm guessing you'll need something on that order.

[Heritage_Head]

When I got my new tv I

moved a few thing around in back (wires) and the static returned. Not as bad as

before but it was there. Even with the power to another outlet. What I found is

that when I turned on my ps3 the static came. So I moved the ps3 plug to the

same outlet as the amp and I also moved the avr to that outlet (set up a power

strip). So the ps3, avr, and emo are on a separate outlet from everything else.

All I get is very clean hiss that you

can hear from about 2ft away. You need

to start from scratch. The key is in where stuff is plugged in. Try and keep 3

prong cables separate from 2 prongs to start.

I feel like an expert in this almost from the time I spent

the first time to the 2^nd. The

first took a long time but when it came back again from moving stuff I knew it

was just a ground loop or interference somewhere in the power. Turn everything off

and as you turn stuff on have your ear next to the horn. As soon as my ps3 came

on I got static and when I powered it down it went away. So had to find the

right combo for the power cords.

[Catharsis147]

I have the same issue. If the RCA plugs are not connected to the amp, and just the speakers, I get no hum....but the second I connect the RCA plugs to my pre-amp, I gte a serious hum. Rather frustrating.

[JasonJCarney]

ok so I did a little bit of trouble shooting this morning. I turned on the the amp first with nothing else on. Got a fairly loud hum fuzzy noise. Then I turned on the Onkyo and the hum actually dereased by like 75%. It was still present however it decreased to the point that I had to put my ear within a foot of the horn to hear it. I didn't try turning on the amp with the RCA's unplugged cause I didn't think of it. I will try that Wednesday.

[SuBXeRo]

I am making another thread for this but my new outlaw 7125 came today an after i bought like 80 bux in wires and unwrapped them all, well, i go to test the amp with the same emo x series rca wires and the system is dead quiet. I get extremely mild static from the horn but its to the point that even the lowest volume basically masks it. I have no hum at all as well. more of a review in pictures in the thread i will create

[Greg Oshiro]

ok so I did a little bit of trouble shooting this morning. I turned on the the amp first with nothing else on. Got a fairly loud hum fuzzy noise. Then I turned on the Onkyo and the hum actually dereased by like 75%. It was still present however it decreased to the point that I had to put my ear within a foot of the horn to hear it. I didn't try turning on the amp with the RCA's unplugged cause I didn't think of it. I will try that Wednesday.

This may be someting different. I *assumed* that the "noise" was hiss, not hum. Hum chasing is a different beast. Turning on the power amp with an unpowered device connected to the amp input will usually result in hum unless there is an output muting relay in that device. Wednesday's results will be helpful.

[Catharsis147]

...so you returned your Emotiva, SuB? Please elaborate.

I noticed in another thread you isolated the problem to one bad channel.....the same happened to me. I have isolated my problem to a bad right (if you are facing the XPA 5) channel. This is after switching my Onkyo and XPA-5 to a different electrical plug, and even using my rear speakers connected as my fronts...this is a fascinating experiment, but I am not happy.

[Catharsis147]

Well, SuB, I see you sold your XPA, and now have an Outlaw...Congrats!

Well, I have not traced my problem to either a complete gain change between the Emtoiva XPA-5 and my receiver/preamp. With everything hooked up, including all cables to the receiver, when I turr on the XPA-5 I get no hum whatsoever. The second I turn on my receiver though, there is the trusty hum. Curious at the very least.

[JasonJCarney]

Well, SuB, I see you sold your XPA, and now have an Outlaw...Congrats! Well, I have not traced my problem to either a complete gain change between the Emtoiva XPA-5 and my receiver/preamp. With everything hooked up, including all cables to the receiver, when I turr on the XPA-5 I get no hum whatsoever. The second I turn on my receiver though, there is the trusty hum. Curious at the very least.

thats funny cause I have the exact opposite issue!

[Catharsis147]

Oy.

Well, I bought some attenuators that should be arriving today. Let's see what that does...I admit, I am using Monoprice Cables too...maybe those need to be changed out to Blue Jeans Cable...

I am a tinkerer, and as someone that worked in the bicycle industry for years, I love solving problems if I can. I do not think it is the amp in my case, as I get no hum unless the receiver is turned on, regardless of where this combo is placed, even on the other side of my place (which has seperate 20 Amp circuits). When the XPA-5 is tunred on by itself, no hum...just the hiss (which I am fine with) out of my RF-7s. Will continue to troubleshoot and report...

[SuBXeRo]

i can only imagine being an electronics designer, manufacturer and retailer and having to deal with people with issues like we have. It can be so many different variables its almost impossibly to diagnose 100%. My experience especially, taking a look back at all of the troubleshooting I did, i came up with so many different tests results its ridiculous. I wish i had the technical expertise to 100% indetify and diagnose the issue with all kinds of fancy equipment but i cant. Klipsch speakers are great for revealing flaws in a system, its a way of telling you how good a piece of equipment is IMO. But shit, it sucks when you do have an issue.