This is a review and detailed measurements of the Kenwood L-05M circa 1978-1981 monoblock amplifier. It is on kind loan from a member.
The L-05M has a timeless design and looks like a modern amplifier you could buy today. It weighs just enough to make you feel like it is substantial but not too heavy. Back panel looks nice too although the member has updated the binding posts:
Here is the description of the unit:
"These were partially restored (but not modified from the original design). All capacitors (except for large filters) were replaced along with all the trimmers, relays, binding posts, and some critical resistors (the ceramics were left in place). When I bought them, some of the original high transition frequency/bandwidth outputs were blown and someone had put "conventional" outputs in there. Whoever had worked on them did not used equivalent replacement parts. They had also put inferior driver transistors in there. I had the the incorrect outputs replaced with modern Sankens in a T03P package with almost identical specifications as the original TO3 package outputs. I wanted to maintain the original performance specs and the only way was with TO3Ps since the TO3s with those specs are no longer available. I also had the driver transistors replaced with appropriate NOS driver transistors with the original specs to not bottleneck the original design. The only major thing I didn't have replaced were the large filter caps, I'm still debating replacing them since the old ones will probably limit the performance results in your tests (especially SINAD)."
Let's see how it measures.
Kenwood L-05M Amplifier Measurements
As usual we start with our dashboard of 5 watts into 4 ohm:
Despite high amount of power supply hum and noise, SINAD is above average for all amps tested:
SNR despite power supply noise was quite good:
Many amps struggle to get to 96 dB at just 5 watts (CD's dynamic range).
Multitone is disturbed by the power supply noise but still turns in good numbers:
Frequency response shows flat in audible band and very wide overall:
Power output is quite good:
But the shape is odd. I think distortion is increasing with power as we already know noise doesn't. Same happens at 8 ohm:
Company spec is 100 watts at 8 ohm and we are already better than that.
Going back to 4 ohm, we see good bit of reserves:
The amp is very well behaved as far as change in output level regardless of frequency:
Subjecting it to different reactive loads doesn't make it unhappy:
While voltage drops (so can't "double down"), response is phase independent.
Finally, it is stable on power up:
Conclusions
The L-05M turns in respectable numbers that is better than over 100 amplifiers tested to date! It is elegant looking, compact and powerful. Assuming you can pick one up at a good price and get it refurbished, it is a very good option for a modern system. I see a pair on sale on ebay for $695 but seems to have cosmetic issues.
-----------
As always, questions, comments, recommendations, etc. are welcome.
Any donations are much appreciated using: https://www.audiosciencereview.com/forum/index.php?threads/how-to-support-audio-science-review.8150/
The L-05M has a timeless design and looks like a modern amplifier you could buy today. It weighs just enough to make you feel like it is substantial but not too heavy. Back panel looks nice too although the member has updated the binding posts:
Here is the description of the unit:
"These were partially restored (but not modified from the original design). All capacitors (except for large filters) were replaced along with all the trimmers, relays, binding posts, and some critical resistors (the ceramics were left in place). When I bought them, some of the original high transition frequency/bandwidth outputs were blown and someone had put "conventional" outputs in there. Whoever had worked on them did not used equivalent replacement parts. They had also put inferior driver transistors in there. I had the the incorrect outputs replaced with modern Sankens in a T03P package with almost identical specifications as the original TO3 package outputs. I wanted to maintain the original performance specs and the only way was with TO3Ps since the TO3s with those specs are no longer available. I also had the driver transistors replaced with appropriate NOS driver transistors with the original specs to not bottleneck the original design. The only major thing I didn't have replaced were the large filter caps, I'm still debating replacing them since the old ones will probably limit the performance results in your tests (especially SINAD)."
Let's see how it measures.
Kenwood L-05M Amplifier Measurements
As usual we start with our dashboard of 5 watts into 4 ohm:
Despite high amount of power supply hum and noise, SINAD is above average for all amps tested:
SNR despite power supply noise was quite good:
Many amps struggle to get to 96 dB at just 5 watts (CD's dynamic range).
Multitone is disturbed by the power supply noise but still turns in good numbers:
Frequency response shows flat in audible band and very wide overall:
Power output is quite good:
But the shape is odd. I think distortion is increasing with power as we already know noise doesn't. Same happens at 8 ohm:
Company spec is 100 watts at 8 ohm and we are already better than that.
Going back to 4 ohm, we see good bit of reserves:
The amp is very well behaved as far as change in output level regardless of frequency:
Subjecting it to different reactive loads doesn't make it unhappy:
While voltage drops (so can't "double down"), response is phase independent.
Finally, it is stable on power up:
Conclusions
The L-05M turns in respectable numbers that is better than over 100 amplifiers tested to date! It is elegant looking, compact and powerful. Assuming you can pick one up at a good price and get it refurbished, it is a very good option for a modern system. I see a pair on sale on ebay for $695 but seems to have cosmetic issues.
-----------
As always, questions, comments, recommendations, etc. are welcome.
Any donations are much appreciated using: https://www.audiosciencereview.com/forum/index.php?threads/how-to-support-audio-science-review.8150/
