Hi everyone,
I recently made an interesting discovery while working on a Marantz 2225 amplifier. While the amp is generally great and has a tone I really enjoy, I always felt something was a bit off in the mid-high and high-frequency range. The upper frequencies seemed to lack coherence, almost as if they were blending together in a way that didn’t sound quite right.
Curious if this was unique to my unit, I reached out to two other people who own the same amplifier to compare notes. It turns out their amps exhibited the same issue. So, I decided to investigate further.
While troubleshooting, I noticed something on the oscilloscope that I had previously overlooked—a high-frequency ringing in the signal. At first, I didn’t think much of it, but it kept nagging at me, so I decided to address it.
The solution, as it turns out, was incredibly simple, but the impact on the sound was nothing short of amazing!
The Fix
The fix involves adding a pair of 152J (1.5nF) capacitors across the feedback resistors (see the attached picture for the exact placement). This small tweak completely eliminated the high-frequency ringing and brought a new level of clarity and coherence to the mid-high and high-frequency range.
After applying the fix to my own unit and experiencing the improvement, I reached out to the two other owners of the Marantz 2225 and offered to perform the same modification on their amps. They both called me after trying it out and said they’d never heard their amplifiers sound this good before!
The transformation is absolutely incredible—it’s as if the amp has been unlocked to its full potential. The highs are now crisp, the mid-highs are beautifully clear, and the overall sound has a newfound precision and warmth.
If you’ve been noticing similar issues with your Marantz 2225, I highly recommend trying this simple mod. The improvement is well worth it, and it’s a straightforward fix for anyone comfortable with a soldering iron.
Feel free to share your thoughts or ask any questions! I’m curious to hear if anyone else has experienced similar issues or tried other modifications to enhance the sound of this classic amplifier.
I recently made an interesting discovery while working on a Marantz 2225 amplifier. While the amp is generally great and has a tone I really enjoy, I always felt something was a bit off in the mid-high and high-frequency range. The upper frequencies seemed to lack coherence, almost as if they were blending together in a way that didn’t sound quite right.
Curious if this was unique to my unit, I reached out to two other people who own the same amplifier to compare notes. It turns out their amps exhibited the same issue. So, I decided to investigate further.
While troubleshooting, I noticed something on the oscilloscope that I had previously overlooked—a high-frequency ringing in the signal. At first, I didn’t think much of it, but it kept nagging at me, so I decided to address it.
The solution, as it turns out, was incredibly simple, but the impact on the sound was nothing short of amazing!
The Fix
The fix involves adding a pair of 152J (1.5nF) capacitors across the feedback resistors (see the attached picture for the exact placement). This small tweak completely eliminated the high-frequency ringing and brought a new level of clarity and coherence to the mid-high and high-frequency range.
After applying the fix to my own unit and experiencing the improvement, I reached out to the two other owners of the Marantz 2225 and offered to perform the same modification on their amps. They both called me after trying it out and said they’d never heard their amplifiers sound this good before!
The transformation is absolutely incredible—it’s as if the amp has been unlocked to its full potential. The highs are now crisp, the mid-highs are beautifully clear, and the overall sound has a newfound precision and warmth.
If you’ve been noticing similar issues with your Marantz 2225, I highly recommend trying this simple mod. The improvement is well worth it, and it’s a straightforward fix for anyone comfortable with a soldering iron.
Feel free to share your thoughts or ask any questions! I’m curious to hear if anyone else has experienced similar issues or tried other modifications to enhance the sound of this classic amplifier.
Attachments
The modification is very simple to perform. Just place the amplifier on its side, remove the bottom plate, and you'll have access to the tone control board to add the capacitors.