More gain in 1 amp than the other

[plumber]

Hi, I don't know if any one has run into this or might have a explanation. I have two Xpa 1's gen 1 driving my L/R fronts and I am getting about 3 db more out of one amp than the other. The amp that is louder has a higher serial #. I wouldn't think that would matter but just throwing that out there. I have tried two different preamps and had the same results. I going to call Emotiva Monday but just wanted to see if anyone had experienced this.
Thanks

[boomzilla]

I'm not sure, but I think I heard garbulky say that some of Emotiva's amps DID change sensitivity during product upgrades. Maybe he'll chime in?

[teaman]

Jan 24, 2015 18:12:22 GMT -5 boomzilla said:

I'm not sure, but I think I heard garbulky say that some of Emotiva's amps DID change sensitivity during product upgrades. Maybe he'll chime in?

I saw that as well. Seems they went from from 32db to 29db gain with Gen 2 or something.

[plumber]

Ok. But both my amps are gen 1.

[geebo]

If both of yours are the same generation, they should have the same gain structure. Gen1 = 32 Gen2 = 29

[repeetavx]

Jan 24, 2015 19:42:24 GMT -5 plumber said:

Ok. But both my amps are gen 1.

First make sure signals going in are really equal. A "Y" cable is one of the best ways to make sure.

If one of the amps truly has that more gain then the other, then one of them is broke.

[plumber]

That's what I figured. So there must be something wrong with one of the amps. But which one. Unfortunately they are out of warranty as of last year. I don't know if I should look for a repair shop around me (Chicagoland area) or just bump up the channel level on the processor and be done with it. But that will always be in the back of my mind. Call me crazy but I Obsess about stupid stuff like that.

[geebo]

Jan 24, 2015 20:03:15 GMT -5 plumber said:

That's what I figured. So there must be something wrong with one of the amps. But which one. Unfortunately they are out of warranty as of last year. I don't know if I should look for a repair shop around me (Chicagoland area) or just bump up the channel level on the processor and be done with it. But that will always be in the back of my mind. Call me crazy but I Obsess about stupid stuff like that.

Have you tried swapping cables? Try swapping speaker cables on the back of the amps then try swapping the interconnects at the amps inputs.

[plumber]

Yes, I tried all that. I had a friend over last night and switched interconnects and speaker cables and he confirmed is was just not me going crazy.
I'm sitting here right now listening to music and it sounds like not only is the gain higher but there is more presence and bass. I hope this might be an easy fix.

[jlamo]

Maybe try swapping speakers left to right and see if the gain follows the speakers and not the amp.

[garbulky]

Look carefully at the faceplate of the XPA-1 that is softer. Right below the XPA-1 in faint letters is it written gen 2? That's my guess.
If not, your input switch may be in the wrong position.
If not, then if it isn't the amp, then it's a problem with the source. But since you already switched cables....it may be the amp.

[ansat]

www.hlabs.com/products/attenuators/ would be a cheap fix for now.

Tony

[klinemj]

Jan 25, 2015 0:34:51 GMT -5 garbulky said:

Look carefully at the faceplate of the XPA-1 that is softer. Right below the XPA-1 in faint letters is it written gen 2? That's my guess.
If not, your input switch may be in the wrong position.
If not, then if it isn't the amp, then it's a problem with the source. But since you already switched cables....it may be the amp.

If both are out of warranty, neither is gen 2.

Mark

[bootman]

Was this determined purely by listening?
Any measurements done?

[vcautokid]

Just to throw another spice into the pot, even though they are the same generation, it is possible, but probably unlikely that the amplifier boards in either amp have possibly different REV builds causing this. Like I said, possible, but not probable, I would contact Emotiva tech support for more. But 3db difference is a bit much especially since you tried another preamplifier etc.

[plumber]

It is only by ear. I do not have equipment to measure. 3 people heard the same results. I would play music and then turn the channel level up on the processor until both speakers sounded equal. But that speaker still doesn't sound as full (lack of depth).

[quattroll]

Recently I had a similar problem with my 1Ls. Some of the same folks in this thread chimed in and their comments were helpful. At one stage I thought that it was a speaker wire that was creating the difference, but after I tested so many different combinations of wire swaps and amp swaps and source swaps, I found the problem seemed to go away, that and my desire to fix it greatly diminished. Weird right? I still have the 1Ls positioned in such a way that I can change left to right and switch speaker wire too. In the beginning of my troubles I was certain there was a 3db difference (same method - boost until balanced), but the permutations became so exhaustive and my ability to keep on the job was interrupted too many times. A careful flow chart in a step by step documented result vs changes must be written down. Also, the more cables you have the better.

Part of my problem as well is that my room is not symmetrical and does not have any treatments. But, I did find that the toe-in in particular did seem to make a big difference. Some had suggested this in response to my thread, but I never knew how big a toe in to use, as I realize I was more straight to the listening position or in fact toe-out. It was only the recent toe-in thread that got me to try crossing over the focal point, such that my left speaker was pointing beyond my right ear and vice versa with the right speaker. Big change! Also I notice that there is a definite muting going on when I sit close to the back wall of my listening room. I have a bean bag there, so my head is often against the wall. Duh! Now when I had my problems I did move away from the wall and I also sat backwards, to see if my ears were clogged or a difference in hearing was creating this effect. Those were not problems though.

Having used UPA-1s and then XPA-5g1, I thought it was odd that I would notice a difference like this. But, I am so impressed with the 1Ls (cd, vinyl, BluRay, cable even) that it might be that the increase in fidelity actually highlighted problems in my room. Ironic, get better gear, now you hear an imbalance. Just another theory guys!

So all I can say is that with additional break-in, my problems with gain imbalance seem to have gone away. The nuances of all of the interacting variables can make it very tricky to determine what could be more than one problem. Also, I am using an XMC-1 which I can trim, and even though I don't want to, is it really a big deal if I do? I think probably not, as I would rather have a balanced image, than a "mathematically correct" set up.

Hopefully my experience will give you some things to try, as I am very appreciative of the helpful comments I received.

[plumber]

Thank you and everyone else for there suggestions and comments. They are very appreciated. I just got done doing some painting. Once I put all the furniture back I'm going to head down stairs and try one last thing. I have a Xpa 5 gen 1 in my system that drives my center and surrounds. I'm going to hookup L/R fronts to it and see what happens. I'm not very optimistic, pretty sure my amp is the problem but it can't hurt. I'm going to call Emotiva tomorrow and hope they will say it's something they have run into before.