Axiom Home Page Forums General Discussion Home Theater XPA 2 Now! A Keeper?

Thats what I thought. It sure seems like a defective unit.

Well let's don't forget I inadvertently smashed one of the inputs before plug in so the jury is still out . . .

BTW the most poignant aspect about your post to me was the anecdote about retreating to the woods in the middle of Ian's party. OMG I miss Vermont, I used to love serene nature as a backdrop every day and took it so much for granted!

At least Dallas squeaked out a win today so I won't be living in Mudville tomorrow .

Yup, I agree having serene nature as a backdrop every day is really beautiful, and northern Ontario where Axiom is located is very calming. But I can't take the brutal winter and relative isolation up there for long periods of time.

I love my visits to Axiom but after 10 days or so I need the hit of the city and urban life.

Regards,
Alan

I'll be curious to hear what Emotiva has to say about this. They're probably getting tired of Axiom owners breaking their amps. Not sure what these sorts of posts say about their designs though...

I agree with the others. I don't think it's your home wiring. If you're pulling too many amps, I'd think you'd see lights flickering or you'd start flipping breakers. Although would it be possible to pull enough amps that you'd start to affect the voltage? I am NOT an electical engineer - so someone please correct me, but aren't volts and amps related? Could an amplifier go into shutdown mode if it was pulling so many amps that the voltage dropped too much?

For the record, I've never had any problems with my cheap LPA-1 driving my whole system, which includes M80's. I can turn the volume up far past the point where it hurts my ears. No problems at all.

Hi Peter,

Yep, volts and amperes are certainly related. I'm not an electrical engineer either, but in theory if there is a voltage sag in a circuit, it would seem feasible that overly aggressive protection circuitry might shut down an amplifier.

Protection circuits can monitor any combination of current flow, voltage and thermal factors, so depending on their implementation, they may react quite differently from one brand or model to another.

JohnK may weigh in here at some point. I'll also check with Tom Cumberand, Axiom's R&D "conehead" (as he refers to himself) who is an electrical engineer and an amplifier designer of long experience.

Regards,
Alan

I wonder how much the voltage would have to sag, I seem to remember the volts ranging between 119 and 122 at least according to my meter, probably closer to 119 when the amperage jumped up, I'll have to watch for that, but there did not seem to be much of a significant dip.

Lonnie asked me to try different cables as a diagnostic.

I changed the interconnects, same problem.

I switched speakers to Polk Reference 10bs and the speakers began to pop, crackle, and fry but the amp did not go into protect.

I used the speaker cables that were connected to the Polks to connect the axioms to the xpa 2 and problem recurred.

It's sad that I've forgotten pretty much everything I learned in my circuit analysis I&II courses. Sad.....

Here's where it stands, look like I may be at a deadend:

Today at 1:52pm, satkartr wrote:
I changed the interconnects, same problem.

I switched speakers to Polk Reference 10bs and the speakers began to pop, crackle, and fry but the amp did not go into protect.

I used the speaker cables that were connected to the Polks to connect the axioms to the xpa 2 and problem recurred.

One other issue: the left unbalanced input to the xpa2 seems loose, kind of droops downward, I think this may have become damaged when I first wrestled the amp out of the box, however I'm not sure this is relevant in that there is no hum or noise at any volume and I have tried running the right channel only and it still goes into protect.


Lonnie responded:

Looks like you found the root cause of the problem. If the amp does not go into protect with different speakers on it, but does when you connect the Axioms. Ipso-facto the Axioms are the cause. Now I don't know if a particular driver is bottoming out and shorting or if the crossover networks have an overlap with an impedance dip or perhaps the crossovers are just heating up and the parts are changing value, but something in the speakers is the cause and I would contact Axiom and see what they say

In my tests, the MPS-1 would not shut down when cranking up my Qs8's (6ohm) to the same level as the 80's (4ohm). Emotiva also blammed the Axiom 80's as being the problem. However, others with Rocket 4ohm floorstanders and bookshelfs had the same problem. Back then I think the amp was not able to drive 4ohm speakers, even though the Axiom's don't fall below 4ohm.

Not sure about this new design.