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creatip123

My personal review of Lepai LP2020A+ Speaker Amplifier (image heavy)

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Posted · Original PosterOP

The original reason I bought the Lepai LP2020A+ was not for speaker use, but for my headphone use, although I did try it with a pair of speaker set, in the end. Read my other topic to get what I mean: http://linustechtips.com/main/topic/174312-trying-to-use-a-speaker-amp-for-a-headphone/

 

Of course, this is not something I would recommend you guys to do, using a speaker amp to power headphones. My headphone is a planar headphone, so it could be fed much higher wattage compared to the usual dynamic driver headphones. I won't be responsible if you decide to try this for yourself, and ends up frying your headphone :)

 

In the topic on the link above, I said that I think it's an overkill, to use a speaker amp that takes hundreds or even 1000+ W from the electrical outlet, just to power a small headphone. That's the reason why I bought the LP2020A+, to save my electric bills :)

 

Well, on with it then.

 

IMG_3455_zps035e54e1.jpg

 

I got mine from a Hong Kong seller in ebay. The price was (and still is) C$25.49. I don't know what the C means, perhaps Canadian dollars? Converted to my currency, it's about US$23-25, with free shipping to my country. It got 2 choices of colors, which are black and white/silver (the body casing. the face and back plates are the same silver). I chose black.

 

IMG_3466_zps9d737413.jpg

 

It arrived about a week after my purchase. The package only contains 2 things, the unit itself, and the power supply adapter, which in my case, AC 220V to DC 13,5V @3A.

 

IMG_3463_zps1d91a833.jpg

 

It's a passive speaker amplifier. Meaning it's intended to power passive (un-powered) speakers.

 

Cosmetically, it exceeded my expectations, for an audio device that costs only $25. All the surface is made of brushed aluminium plates. You can see clearly the brush lines in the silver front and back plates, like in the picture above. This really gives a good aesthetic and elegant look to it. The unit also feels solid, with no rattling or loose parts if you shake it. Same goes with the power supply adapter, no loose parts if you shake it. The sign of the cheap price comes from the cheapo buttons. The on-off switch and the knobs are all cheap plastics, and you can feel it right away the first time you touch them. The knobs looks good in the picture because they're shiny silver, but in reality you can tell right away. But honestly, I didn't expect much, considering the price. Also, you can always get replacement knobs anyway, maybe prettier metal knobs, from radioshacks or the kind. 

 

You can see from the picture above, there are bolt grooves on the bottom. This is for if you want to use the amp in your vehicle, like cars (small chance, because most likely your car already got a sound system anyway :) ), boats/yachts, or even motorbikes. The power supply gives the output of DC 13.5V, but DC 12V like in most vehicles' batteries should run it just fine. Be careful if installing it to a small battery, like motorbike's though, it may drain your battery much faster than you expect :)

 

The dimension is quite small, 14x11.5x4cm, including the bottom bolt grooves, protruding knobs, and protruding jacks in the back. I don't have a scale handy, but I'm estimating it weighs less than 500g (half a kg). It weighs about the same as my HE-400 headphone. The power supply also doesn't weigh very much.

 

IMG_3457_zpsf238accc.jpg

 

The front plate got an on-off switch, bypass button (the one labeled 'tone' and 'direct'), treble and bass control, and a volume knob.

 

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The volume knob got a LED ring around it that will light up when it's powered on. Handy in darker rooms :)

 

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The back plate got a power input jack, audio input jacks, and speaker cable clamps. For audio input, you have the option of using RCA connectors, or mini stereo (3,5mm) connectors. I never tried plugging both (RCA + mini stereo) though, so I don't know what it'd do. Best possibility is it mix the input. Worst possibility is it short circuits :) It's rated for speakers ranging 4-8 ohms. 

 

From the markings on the top casing, it says it can output max 20W RMS. I'm guessing it's the total of 2 channels, meaning 10W each channel. (Edit: Per channel ~8W in 8 ohm, ~15W in 4 ohm -credit to @Lutkeveld -) Considering the size and weight, and even the power it needs, the power output is quite impressive. 

 

LP2020A+ is a Class-T amplifier. Class-T is actually a class-D amplifier switched at a very high frequency (50MHz). So 'Class-T' isn't a different class of audio amplifier, but rather a different way of implementing a class-D amplifier circuits. It's a registered trademark of Tripath (a company). Class-T is claimed to improve the control scheme to create more efficient and higher quality audio amplification (http://en.wikipedia.org/wiki/Class_T_amplifier)

 

 

Before I bought this, I did a little research and reading on the net. Some people claim that Lepai products are actually crappy/mediocre, excluding this LP2020A+ which many people claims to be the 'gem' of Lepai, and the only Lepai product worth buying. 

 

IMG_3516_zpsd05cab54.jpg

 

I tried this amp with my pair of very old, but still working, Kenwood 6 ohms 3-way speaker (almost 20 years old, no kidding!). You can see the size comparison in the picture. It's not that the speakers are very big, only measures 30.5x18x20cm, but rather the LP2020A+ is very small. 

 

So what do I think about the result? I must say, for such a small thing, and cheap price, this thing packs a punch. It can power the speakers just fine, without any problem, and it gets quite loud, louder than my convenience point. It also got a start up-shutdown protection circuit, meaning you won't get that annoying pops when turning it on or off, even when the volume knob is still set somewhere in the middle. The sound itself is quite good. It doesn't 'miraculously transform the sounds into unicorn puking rainbows' or such, but got quite nice clarity and frequency separations. In short, it isn't 'crazy good', but it does the job very well, more than what I expected from the price and even size. 

 

The tone control (the treble and bass knobs) on the other hand, aren't very good. When I fiddle with the knobs, I ended up affecting other frequencies I don't wanna change. In other words, not very detailed. For general tone controls, sure, but for finer adjustments, meh.... I ended up switching it to bypass (or 'direct'), and controlling the EQ from my PC. 

 

In conclusion, I'd categorize the LP2020A+ a must-have if you got small-medium passive speakers. Even if you don't need it (maybe you already have them hooked to an amp), with that kind of price ($25), it's good to have one as a backup unit. When your main amp breaks, just pull out this little sucker, and you're good to go again... :)

 

Now, in the start of this topic, I wrote that I originally bought this to power my headphone, right? If you read my other topic from the link above, I used an L-pad (resistor circuits) to bridge the connection between the output of my big amp to my headphone. The basic concept was to give the amp's output a dummy load, so it won't go berserk on my headphone. So I pulled those L-pad from my old amp, and install it to the LP2020A+.

 

First, I tried with the 7.5 + 1.5 ohms, which is 9 ohms dummy load. Turned out it's too much strain on the LP2020A+. I got small volumes, and when a song hits low notes (kicks or basses), some kind of over-drain protection circuit kicked in. I could hear a soft click inside the amp, the sounds were cut-off, and resumed after 1-2 seconds. 

 

IMG_3519_zpscb3af6b8.jpg

 

So I went 'commando', and plugged the cables directly to the speaker outputs. Turned out it works just fine on my HE-400. I got hisses, which from my previous experience plugging my headphone to a speaker amp, is no surprise. The hisses were only annoying when no sounds is coming out. When I'm playing a song, the hisses got drowned easily. The power output of this amp sure enough could push my headphone quite nicely. With 50% of Foobar's volume, I could only set the volume knob to around 9-10 o'clock. It's not that my HE-400 won't work without a big powered amp like this, but with big powered amp, it sounds better. The kicks are punchier and tighter, the overall sounds are wider. 

 

Again, I'm not recommending you guys to do what I did, using a speaker amp to power your headphone. My headphone, the HE-400, is a planar headphone. With other planars, such as Fostex, Audeze, etc, you might get away with this, but not with dynamic driver headphones. You might or might not destroy your dynamic driver headphones. Better not try it... :)

 

I used the LP2020A+ to power my HE-400 for about 1 week, and then my order of Aune T1 MK2 arrived. Turned out the T1 sounds better (its DAC, to be precise) and got adequate power, so I switched to the T1 for my HE-400. Review about the T1 coming up later :)

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Per channel ~8W in 8 ohm, ~15W in 4 ohm. I wouldn't recommend to use this in your car because of the filthy voltage spike the alternator generates. 

 

Edit: TA2020 datasheet says 13 in 8 and 22 in 4 ohms but that's with 10% THD+N. At usable volume without distortion (<0.1) it will be around the numbers mentioned above, maybe slightly less due to not so great PCB design.

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Posted · Original PosterOP

Per channel ~8W in 8 ohm, ~15W in 4 ohm. I wouldn't recommend to use this in your car because of the filthy voltage spike the alternator generates. 

 

Thanx, edited the post, with credit :)

 

Noted for the car part. Maybe needs a capacitor bank? I don't know much about car audio, just quoted what the manual book said  :D

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Car radio and amps have a kind of stabilization circuit IIRC. A 4700uf (or so) cap parallel on the input will probably be sufficient to keep the amp safe. If not, lesson learned, buy a new amp ;p.

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Posted · Original PosterOP

I used Lepai 2020+ with a 20 year old Sony stereo speakers(back when they made good stereo speakers),and this little thing managed to make it sound better than my desktop speakers which costs quadraple the price of Lepai,and to think i was going to give away the speakers :unsure:

 

Yeah, 80's and 90's middle class speakers, like the ones in Hi-fis' are the best. Looks good, sounds good, and durable as hell...

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Great review! I'm planning to order one too. 

 

May I ask where you bought this cable? I think I need it to get the output from the amp to my Logitech Z623. Thank you!

 

IMG_3519_zpscb3af6b8.jpg

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Great review! I'm planning to order one too. 

May I ask where you bought this cable? I think I need it to get the output from the amp to my Logitech Z623. Thank you

 

You don't need this. Plug the 3.5mm from the Z623 in the device (pc, mobile, laptop etc) that you plan on using. It has an amp inside, which will do all the work for you.

You don't need more than the stuff that's in the box.

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Posted · Original PosterOP

Great review! I'm planning to order one too. 

 

May I ask where you bought this cable? I think I need it to get the output from the amp to my Logitech Z623. Thank you!

 

IMG_3519_zpscb3af6b8.jpg

 

That is a cheap-as-ass DIY plug. 80 cents 6.35mm stereo female jack, cabled with decent gauge common wires, 50 cents/meter. Nothing special, but does the job. 

 

And like said, you won't need the lepai for your active speakers. Active speakers + external amp = 2 serial amps. They can cause problems, i.e. noise floors, buzzing, hissing, etc. 

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That is a cheap-as-ass DIY plug. 80 cents 6.35mm stereo female jack, cabled with decent gauge common wires, 50 cents/meter. Nothing special, but does the job. 

 

And like said, you won't need the lepai for your active speakers. Active speakers + external amp = 2 serial amps. They can cause problems, i.e. noise floors, buzzing, hissing, etc. 

 

 

You don't need this. Plug the 3.5mm from the Z623 in the device (pc, mobile, laptop etc) that you plan on using. It has an amp inside, which will do all the work for you.

You don't need more than the stuff that's in the box.

 

Thanks a lot guys for the insight. I learn something new everyday. Cheers!

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