Hello, I have two Xa60 mono blocks that I love and that I use for my Tannoy Kensington GR with a Mcintosh pre-amp. I bought them used some time ago from a professional. I wonder what the needle on the front is for, in fact when I turn on the device, the needle blocks towards the right, I don't know if this is normal, because I see an intermediate position at noon but the needle never went there. I would like to point out that I don't listen at very high volume. Thanks for help
The bias has been turned up too high. There may be overheating.
Readjust it for more near the center.
Readjust it for more near the center.
Have a local skilled technician check out the amplifiers, and the bias adjustment will be part of that.
This is important because it is the amount of current that flows continuously in the output stage.
Too much current can cause overheating and damage. It can be done at home if the technician visits.
In fact they may work better if adjusted at home, because of AC line voltage variation.
This is important because it is the amount of current that flows continuously in the output stage.
Too much current can cause overheating and damage. It can be done at home if the technician visits.
In fact they may work better if adjusted at home, because of AC line voltage variation.
thank you, I understood correctly, so a merchant sold me a broken device without my knowing it and which I have been using for 2 years with the risk of damaging it even more. Glad to hear it! Do you think it will look even better after repair, it is already good, and is any local professional capable of doing this kind of thing? Thanks a lot
It is probably not broken, but misadjusted. This is considered to be routine maintenance, although it is unusual for the bias setting
to be so far off. Hopefully it just needs an adjustment, but it is possible for there to be other problems causing excessive bias current, such as a bad resistor. This should also be checked.
A local technician that you have used before and trust, should be able to check out the amplifiers.
The amplifiers are heavy and large, not ideal for shipping, especially if you no longer have the original boxes.
to be so far off. Hopefully it just needs an adjustment, but it is possible for there to be other problems causing excessive bias current, such as a bad resistor. This should also be checked.
A local technician that you have used before and trust, should be able to check out the amplifiers.
The amplifiers are heavy and large, not ideal for shipping, especially if you no longer have the original boxes.
thank you, I have the boxes but I prefer to work locally. So, do you know if this problem has an impact on listening quality? For that I thank you and I think that you have completely answered my question but I am going to ask you a more general one, with a friend we were wondering what this needle was for. So if I understand correctly, at noon everything is fine, right this is a sign of a problem? Is that right? I couldn't find this information in the manual
This is a question that I think may be useful to others.
This is a question that I think may be useful to others.
This bias adjustment is not extremely critical to sound or reliability, although some might think the sound improves
a little at a higher bias setting. But the amplifier will run hotter, cost more in electricity, and have reduced reliability.
The designer intended the amplifier bias to be adjusted to the mark on the meter during normal operation,
and that's what I would do. But since the actual setting now is much higher, I would have the technician check it out
and verify there are no problems other than the bias needing to be reset. I presume both amplifiers are the same.
a little at a higher bias setting. But the amplifier will run hotter, cost more in electricity, and have reduced reliability.
The designer intended the amplifier bias to be adjusted to the mark on the meter during normal operation,
and that's what I would do. But since the actual setting now is much higher, I would have the technician check it out
and verify there are no problems other than the bias needing to be reset. I presume both amplifiers are the same.
yes the 2 are identical, I had thought of a polarity problem and I reversed the plug, without that changing anything
Quite possibly they were deliberately set this way by the previous owner, who though they would sound better.
But the higher internal heating is a potential problem.
But the higher internal heating is a potential problem.
1. simple check-up by competent technician will resolve is there any issue with Iq ( standing current, thus overall dissipation) or is it "just" that someone miss-aligned needle settings
2. if you have temp. of heatsinks in ballpark of 50C, say with 25C ambient, Iq setting is good and just amp's needle meters did met some Gremlin in previous life
3. in every case you need technician
4. Needle meters - their function is ( by memory) described in User manual; they're showing overall power consumption of amp, or Iq as such, if you prefer that as observation point; normal position is somewhere around mid position; when needle is moving (slightly), amp is moving from pure Class A to nasty KlunK!ing B Class .......... but who cares - that's PL, sounding cozy in whatever Class it is
5. Note for technician - expect 175mV as proper, across each 1R Mosfet source resistor; needlemeter fiddle-dee with trimpot labeled P3
6. Note for you:
2. if you have temp. of heatsinks in ballpark of 50C, say with 25C ambient, Iq setting is good and just amp's needle meters did met some Gremlin in previous life
3. in every case you need technician
4. Needle meters - their function is ( by memory) described in User manual; they're showing overall power consumption of amp, or Iq as such, if you prefer that as observation point; normal position is somewhere around mid position; when needle is moving (slightly), amp is moving from pure Class A to nasty KlunK!ing B Class .......... but who cares - that's PL, sounding cozy in whatever Class it is
5. Note for technician - expect 175mV as proper, across each 1R Mosfet source resistor; needlemeter fiddle-dee with trimpot labeled P3
6. Note for you:
Unless you can't put your hand on the sinks, I would say there's no rush.
thanks à lot,
I can't leave my hand for very long, i think it's more than 60
I'm going to go to a repair shop as soon as possible.
I can't leave my hand for very long, i think it's more than 60
I'm going to go to a repair shop as soon as possible.
cheaper to just send them to OPLDF
usual place where all Audiophoolerytweakery is ending .......
my technician asks if it is possible to have a schematic or a bias adjustment procedure
and what is this meter for?
the deadline is 3 months ouch
and what is this meter for?
the deadline is 3 months ouch
