A few years ago I built a bog standard Aleph J amplifier using the DIY Audio boards and chassis. It drove my 88db efficient KEF R500 speakers without any issue and was the mainstay of my system for quite a while. It sounded great at mid-to-not quite loud levels.
I got back into tubes and kept the Aleph J as a second amplifier. Fast forward two-something years: I pulled the Aleph out of the closet and plugged it back in. Same speakers, same tube preamplifier... but now the Aleph seems to clip very, very easily. Sounding more like a 1W amplifier than well, its rated power. I checked the main supply voltages/offset and can't find anything obvious. What to check next?
Clipping happens with both channels which makes me think power supply! My tube amp is no power house - rated at 35WPC (old school) with a breeze blowing behind it. It drives the KEFs without any issue. Positively flummoxed by the Aleph change in sound.
I got back into tubes and kept the Aleph J as a second amplifier. Fast forward two-something years: I pulled the Aleph out of the closet and plugged it back in. Same speakers, same tube preamplifier... but now the Aleph seems to clip very, very easily. Sounding more like a 1W amplifier than well, its rated power. I checked the main supply voltages/offset and can't find anything obvious. What to check next?
Clipping happens with both channels which makes me think power supply! My tube amp is no power house - rated at 35WPC (old school) with a breeze blowing behind it. It drives the KEFs without any issue. Positively flummoxed by the Aleph change in sound.
Rails are +/- 21 VDC, offset is roughly 20mV per channel. Bias for both channels is at 420mV measured across the rightmost .47ohm resistor.
RCA inputs haven't been touched, nonetheless I checked and they don't measure any shorts.
It's been awhile since I worked on this amp but, at least from the build guide, everything is measuring as it should. Hence my confusion!
RCA inputs haven't been touched, nonetheless I checked and they don't measure any shorts.
It's been awhile since I worked on this amp but, at least from the build guide, everything is measuring as it should. Hence my confusion!
I didn't ask are your RCA inputs shorted; I was reminding you to check what's with negative input on each channel, if you're using SE (RCA) input
since there are different scenarios possible, which input arrangement you're using, and what you did with -IN in case you're using SE (RCA) input, that area demands your explanation
post pics, present situation
since there are different scenarios possible, which input arrangement you're using, and what you did with -IN in case you're using SE (RCA) input, that area demands your explanation
post pics, present situation
This is covered above, but I'll say it slightly differently, since there's been no response. Maybe folks are handling via PM.
Are you sure the amp is actually clipping, or does it just sound "off" and/or the output isn't what you expect?
The amp was clearly performing well prior to tucking it away for a nap. So, unless it's a solder joint or something mechanical, let's start with one I'd consider easy to check off the list.
Does the AJ have both XLR and RCA inputs?
Are you sure the amp is actually clipping, or does it just sound "off" and/or the output isn't what you expect?
The amp was clearly performing well prior to tucking it away for a nap. So, unless it's a solder joint or something mechanical, let's start with one I'd consider easy to check off the list.
Does the AJ have both XLR and RCA inputs?
If yes, are you using the RCA inputs?
If yes, did you short pin 1 to pin 3 of your XLR inputs?
When I first built my M2 I had the solder joint problem. It had set still playing fine in the same place. One day I got the idea to move it upstairs to different set up. Acted all weird and puny. Traced it down to a wire on power supply board that hadn't been soldered! Wire was snug, but not near enough. Setting amp down was enough to jiggle it.