Axiom Home Page Forums General Discussion Technical Questions My EP175 does not wake up, HELP PLEASE!

To the Axiom community,

Since new, when playing music on my system, my EP175 won't come out of sleep mode unless, while powered, I unplug & plug back in the RCA connector. Another way to wake it up is setting the volume of my receiver too high and then bring it down to a comfortable level, however after a short period the sub goes back to sleep mode.

I am using a fairly decent AR pro cable, the output level of the sub in the receiver is set to 0db and the volume in the sub itself is set to the middle. I have tried playing with these levels and have seen no changes.

I explained this to Joe Vasallo, he kindly agreed to repair the sub amplifier. I sent it over and just received it back after two weeks of anxiety. Just after reconnecting... an unpleasant surprise... the problem is still there... I couldn't believe it! The one new thing that I just found out is that if I knock gently on the sub amplifier, the sub sometimes comes out of sleep mode randomly and then goes back to sleep again.

Any guidance would be highly appreciated.

Thanks much,
Guillermo Schwarz

Hmm... What is the approximate position of your sub's level control? Also, what is your receiver's subwoofer level setting (-2dB, +1dB, etc)?

Guillermo, you said that one way to rouse it from its slumber was to set the receiver volume "too high" and also that you've "tried playing" with the receiver sub output level. Unless the sub auto on is just plain defective(possible) and wasn't corrected the first time, it would seem that setting the receiver sub output higher to get more voltage out and compensating by setting the level control on the sub lower than the middle should work(unless you mean that you already tried this).

The position of the sub's level control is exactly at the middle, as recommended. The receiver's sub level is set at 0dB. I have unsuccessfully tried all settings from -5dB to +5dB.

John,
This is exactly what I tried to do in the first place, increasing the receiver sub output level and compensating by lowering the sub level control below the middle. This test made a lot of sense to me and did not work.

What do you think of the latest finding I described in my first message about knocking on the back of the sub.

Thanks much,
Guillermo

That "wake by knocking" thing definitely sounds to me like a bona fide defective amp.

I have the same problem with my EP125; Joe in service was very helpful and I sent the sub's amp section to him for testing and it was performing to spec. I've 'sort of' solved the problem by adding +10db in my receiver and another +10 via an old equalizer that I put in-between the amp and the sub. However, this works out really badly at higher volume levels and I'm always having to adjust the equalizer to different values. I wish these subs had more sensitive auto on/off circuitry, or the ability to bypass the auto-off feature. I'm a little conflicted about the whole thing, in that Axiom was super good about looking into the problem, but in the end the product doesn't meet my (and apparently your) needs.

Guillermo, most receivers can supply more than enough voltage on their sub output to turn on and drive the sub to a very high level. So, unless your receiver for some reason can't supply enough voltage even when, as you've said, you turn up the sub out, it would appear that the problem would be in the sub amp. The "knocking" solution would, of course, also tend to indicate this. Maybe you should speak with Joe again.

I'd thoroughly check (and swap) the cables. If that doens't lead anywhere...

It sounds symptomatic of a cracked trace, cold solder or the like. If you need to have your subwoofer amp's volume set very high for the problem to suddenly cure itself, it's likely a bad connection (trace or solder) in the output stage. A wild guess having not seen or tested it myself :-), I'd say it's a cracked trace (since knocking gently seems to cause it to change). But if replugging the RCA fixes it, I'd be wary of parts that are stressed when you plug in the RCA. Having not torn apart an EP175, I don't know what those might be other than the jacks themselves.

I had a very similar problem in one of my Polk RT2000p's. The subwoofer amp wouldn't kick in until extremely loud volumes at both the input (speaker level) and the output (volume on the subwoofer amp). It was due to a cracked trace, I suspect caused by damage during shipping (since it arrived with a chip in the base plate. Once it came on, it worked fine all the way down to very low levels, it just took loads of potential for it to come on. Any evidence of rough treatment during shipping?

It should be fairly easy to rule out receiver problems with a volt meter, if you have one.