I have this three-piece set utilizing the EX-442, MC-101 and TS-108 tuner. I am wanting to go through and freshen them up a bit as I found they were having a problem. Playing them they sound fantastic, but one day I was driving them fairly hard, and I found some popping noises coming from a mid range in a pair of my JBL L7 towers. I happen to have a few pairs of these, so I swapped out the mid range and sure enough it was doing it again. Through some testing and swapping of cables I found the problem to be the amplifier. That’s when I read that, this was likely a mosfet getting noisy.
First off, what is the best method of determining which mosfet is the culprit?
So it used 2SK1058 and 2SJ162 mosfets. I was hoping to get an idea of how good these devices are. Would it be better for me to try to seek out originals and hope that I don’t have to replace too many to eliminate the noise? My other option is to buy all new mosfets from Exicon. It looks like the ECX10N20 and ECX10P20 would be the appropriate replacements for these. If I did go this route, then I would probably buy a couple sleeves of each, having 60 of each on hand for future projects. Then at a later time get the bigger ECW20N/P20, or would these be better in this situation now? I’m guessing the ECX would be just fine as it is rated to be a bit more robust than these originals.
How do these new devices compare to the originals of the amplifier? I know when it comes to BJTs there are certain devices out there that are considered superior sonically and are coveted. You wouldn’t replace these with any new modern device as it would be a downgrade. I’m just trying to see if this is a similar situation.
Thank you,
Dan
First off, what is the best method of determining which mosfet is the culprit?
So it used 2SK1058 and 2SJ162 mosfets. I was hoping to get an idea of how good these devices are. Would it be better for me to try to seek out originals and hope that I don’t have to replace too many to eliminate the noise? My other option is to buy all new mosfets from Exicon. It looks like the ECX10N20 and ECX10P20 would be the appropriate replacements for these. If I did go this route, then I would probably buy a couple sleeves of each, having 60 of each on hand for future projects. Then at a later time get the bigger ECW20N/P20, or would these be better in this situation now? I’m guessing the ECX would be just fine as it is rated to be a bit more robust than these originals.
How do these new devices compare to the originals of the amplifier? I know when it comes to BJTs there are certain devices out there that are considered superior sonically and are coveted. You wouldn’t replace these with any new modern device as it would be a downgrade. I’m just trying to see if this is a similar situation.
Thank you,
Dan
From various comments around the forum, they are the same or slightly better. Do you have schematics of the amplifier you want to mod?
It seems a bit odd that the MOSFETs would make occasional odd sounds though. Perhaps a dry solder joint + vibration?
It seems a bit odd that the MOSFETs would make occasional odd sounds though. Perhaps a dry solder joint + vibration?
Thank you so much for the response. The joints are something to definitely inspect. The noise is only made once you hit a certain volume threshold and only on dynamic transients.
Oddly, the service manual has three different schematics for the amp, but this one looks like it matches mine. Though the outputs are labeled as different devices.
Dan