{"id":571,"date":"2017-07-29T14:51:26","date_gmt":"2017-07-29T22:51:26","guid":{"rendered":"http:\/\/wonghoi.humgar.com\/blog\/?p=571"},"modified":"2018-02-06T01:28:33","modified_gmt":"2018-02-06T09:28:33","slug":"lepy-lp-2024a-class-t-amplifier-mod","status":"publish","type":"post","link":"https:\/\/wonghoi.humgar.com\/blog\/2017\/07\/29\/lepy-lp-2024a-class-t-amplifier-mod\/","title":{"rendered":"Lepy LP-2024A+ Class T Amplifier Mod"},"content":{"rendered":"

My traditional Hi-Fi amplifier drains a lot of power and heats up my room\u00a0when I’m not using it<\/span>. The summer heat prompted me to look into Class-D amplifiers as they’re highly energy efficient.<\/span><\/p>\n

I bought a Lepy LP-2024A+, a Class-T amplifier (It’s T<\/strong>ripath’s improvement over Class-D amplfiers) for $22 shipped. It sounded good over a narrow range of volume, as I can hear the background sound details on my ADS 200 speakers.<\/p>\n

Unfortunately, strong bass components in certain music gets distorted, a sign that the amplifier cannot deliver fast energy impulses. To put it simply, I enjoyed the treble but not the bass with this amplifier.<\/p>\n

I saw some mods reports on the older TA-2020A+ based units (like LP-2020A+), but as of now, only one Japanese blog site<\/a> talk about switching out input stage op-amps without other changes. So I decided to do my own mod and post the results here.<\/p>\n

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First, the unit came with a dinky 2200uF capacitor for power smoothing. I upgraded it to 6800uF. I happen to have a 12uH inductor with thick wires, so I replaced the toroid inductor (as in the LC power smoothing pair) with it while I’m at it.<\/p>\n

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Then I replaced all the remaining white-label capacitors with decent brands (Wruth, Nichicon, Panasonic, CDE), all rated at 105 degC, sometimes with higher voltage ratings depends on which brand-name parts Newark has on sale when I order it.<\/p>\n

Then I upgraded the 4 output stage inductors with Wruth 7447452100 rated 10uH 4.5A. Tripath’s datasheet says 2A, so I supposed the one populated on board would be less than that.<\/p>\n

I also replaced the SMD (1206) ceramic capacitors at the output stage (very close to the speaker wire terminals) with Polyester Film (for the taller 0.47uF ceramic chips) and NP0\/C0G (the thinner 0.1uF ceramic) to improve linearity. I suspect this change helped to reduce the listening fatigue for treble components of the music I’m listening to. Now I don’t have to tone down the treble gain (knob) that aggressively.<\/p>\n

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As prompted by the Japanese blog site, I ordered some LT1364, but the improvement isn’t that big since the NE5532 wasn’t bad in the first place:<\/p>\n

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The bass and drums are much more enjoyable after the mod, since the improved power handling reduced the bass distortion on bass impulses. The amplifier is still 15W (7.5W+7.5W) dictated by TA-2024A+, but I rarely want to crank the music up louder than that anyway.<\/p>\n

As a bonus, I took a thermal image with my Seek Thermal Imager:<\/p>\n

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The input stage ICs LT1634 are 118 deg F:<\/p>\n

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Update [02\/06\/2018] I did some experiments with external capacitors and realized that the real problem is the crappy 13.5V@3A power supply that came with it. Yes, I tested it with a DC load and it can really do 3A, but it has a weird behavior: when there’s\u00a0a huge power draw (like from a bass drum) that drops the voltage level below 11.5V, the power supply starts oscillating from 10V to 11.5V (never gets above that even when I stopped the music) with a regular hissing noise of around 1Hz physically from the power supply itself. I had to turn the unit off for it to ramp back to 13.5V.<\/span><\/p>\n

Then I used my HP 6033A systems power supply (can do 30A, relatively clean power with fast transient recovery) and observed the rail voltage and compared it to when I power the LP-2024A+ with a big capacitor + original power supply. It’s clear that no capacitor is big enough to cover the flaw of that crappy power supply that came with the amp.<\/p>\n

After the power supply issue is resolved, even loud music sounds smooth, expressing the 3D acoustic image crisply through my ADS 200 speakers: I felt like a person is talking\/singing right in front of me than some loudspeaker generated sound. It’s so crisp that I can hear each individual string pluck. Bass is deep too after I added a ADS sub 6 subwoofer.\u00a0I’ve been listening to “the Phantom Of the Opera” CDs ever since high school and I’m still rediscovering new musical details with this amplifier + ADS speakers!\u00a0<\/span><\/p>\n

Before the mod, I would hesitate to make it my main amplifier and might want to go back to my Denon AVR-988 for serious listening. It took me quite a while to tune my Denon to sound good, but it works right out of the box on my modified Lepy LP-2024A+!<\/p>\n

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Update [08\/21\/2017]: Based on people’s comment (in audiokarma) on TA-2020A+ vs TPA3116, I decided to give it a shot and ordered Nobsound’s 50W model.<\/p>\n

Actually before this LP-2024A+, I modded a Pyle TA-2020A and was disappointed at the clarity is totally lacking compared to the lower powered LP-2024A+. I thought it could be Pyle’s terrible implementation of TA-2020A+, but after hearing TPA3316, I observed these:<\/p>\n