Modding the Lepai T2020A+

[Jake]

Try running a 2020 on a 19 V laptop supply with a 3+ A rating. It will make a world of difference at higher volumes.

Max supply voltage is supposed to be 14.6v

[Millstonemike]

Try running a 2020 on a 19 V laptop supply with a 3+ A rating. It will make a world of difference at higher volumes.

[Ynantr]

thanks for sharing, very useful information for me!

[bullittstang]

The only difference I see in the PSU's is the stock one is 2.1mmx5.5mm where your replacement is 2.5mmx5.5mm, which might not be making good contact with the center pin since it's larger. I would check with the volt meter and make sure the new PSU is working properly. Otherwise, I don't see anything to keep them from working (the pin layout (center positive) is the same as original).

[Mirskyman]

Hi everyone. I just joined these forums so I could post on this thread. I know very little about electronics but I just bought a Lepai 2020A+ from Parts Express. I also got a more powerful power supply after reading that it might make the Lepai's sound less distorted at higher volume.

This is the power supply I bought on Amazon after reading some reviews there from people who'd used the power supply successfully with their Lepai:

http://amzn.to/1pWkKKB

However, it didn't work with my Lepai. When I connected the Lepai to the power supply and turned on the Lepai, the blue LED light went on for a second, then went out. And the Lepai wouldn't work. So I'm now using the less powerful power supply that came with the Lepai.

I called Parts Express to see if they sold a more powerful power supply that might work with the Lepai and I was told they don't.

I don't want to waste more money on other power supplies that may not work with my Lepai.

However, I am confused and curious: why would the powerful supply that I bought from Amazon work with other people's Lepai 2020A+ but not mine? Do you think it's the power supply or my Lepai?

Thanks in advance for your replies.

[Less Opinion]

Re: Modding the Lepai T2020A+ First attempt! And Questions.

I have purchased the amp and the specified caps. This will be my first attempt at amp mods, I have the soldering skills but I truly do not no squat about the electronics so I hope you know your stuff. I will post some results asap. If you can help please answer the following questions.

1. I am upgrading my computer power supply and intend to use the old one as the power supply for the Lepai That's 12v and approx 16 amp supply, do you fore see any issues with this concerning noise or over power/amperage? this is the 12v supply for the motherboard so I assume it would be a pretty clean source.

2. RE: the two 50v 1.7uf caps. You tried 2.2uf caps and had distortion issues, I can find 1.8uf and 1.6uf caps, would either of these be a viable option for the 1.7uf cap if so which would be the preference or just leave well enough alone.

3. RE: the Volume and tone Pots. I have read these are the cheapest form of junk that you can obtain, since they are the most used part of the amp wear and tear wise I would like to replace the just for the sake of doing it right (and I hate bad scratchy pots)
If you are aware of what I need as to the parts no.s manufacturer etc. Please advise.
P/S I'm not after the best of the best just a decent quality pot that will replace the stock junk without hassle.

4. RE: There is no polarity for the 6 output caps, is that correct?
Thanks for your help in advance. Less Opinion

[Chris Roemer]

Re: Modding the Lepai T2020A+

(NOT an amp expert.)

I'd use 63v caps (or slightly higher, within +10% to +20% IF 63v caps aren't available) with 2.2uF or 3.3uF of storage. Given a choice between the two, MORE storage can't really be bad, RIGHT?

That said, I wouldn't go higher than 3.3uF unless you can verify that the supplying circuit can reliably handle the current demands that greater storage might require.

IF these are used for DC supply, then they need to be polarized electrolytics, right (which "film" caps are not - correct?)?

[Dan Willett]

Re: Modding the Lepai T2020A+

I bought a Lepai - LP-2020A+ T-Amp from Parts Express on 9/3/2015 & plan on replacing the capacitors. I have the newest model ( model # 30418B) & the newest models don't have the model # printed on the board anymore, but instead printed on a sticker on the bottom of the chassis. I can't find a schematic anywhere for my model board on the internet & have a problem with finding out what the exact values of C30 & C31 are for my model board, these are the SMD chip capacitors on the input signal path circuit. I have found out that the 2013 models & up use a value of 2uF 63v or 2.2uF 63v or 3.3uf 63v for C30 & C31. The SMD Resistors on the input signal path circuit of the newest model boards all have the exact same values. What happens when you raise or lower capacitance of the input signal path circuit? Will I burn out my board if I try a 2uF 63v or 2.2uF 63v or 3.3uF 63v film capacitor without knowing what the value I have on my model board to replace it with correctly to exact specs? I need help with this & would greatly appreciate it if anyone can give me an expert opinion on this problem I have.

[cheap-fi]

Re: Modding the Lepai T2020A+

Could mods similar to these that you are doing for the Lepai T2020A work on the Lepai LP-168HA?

I seem to remember that some people had complaints about the sound from the little 2.1 channel amplifier.

[Sydney]

Re: Modding the Lepai T2020A+

A little pragmatism is in order to meet that price point...
A 1 dollar hamburger can't be transformed into Kobe beef :D

[tinkertoys]

Re: Modding the Lepai T2020A+

kevin, it wasnt 20 bucks for the internal parts to do all 3 of my 2020A's, they might have taken an hour each, 2 of em being run off a 12v battery anyhow. the class D might be better quality or not. 112 bucks for modded lepai, awful crazy spendy. the T amp internally is digital switching, taking analog to digital, amplifying, then out through a low pass filter to cut the 60-90khz carrier out. being digital it runs very cool-cold and is something 85-90% efficient, isnt going to chow down on input current vs wattage output.. great choice for something like an electric golf cart, or a boat that doesnt have a charging system onboard is where I'm using one of em driving a pair of pyle 8" marine coaxials, plenty-very loud for toobing on a tow line 55ft behind it, surprisingly. after changing a bunch of caps, even better now.

[tinkertoys]

Re: Modding the Lepai T2020A+

deewalk, to me the best bet would be to get my hands on more efficient speakers to hook up, paying a lot less attention to power handling capacity, whole lot more attention to Db out at 1w1m. at fryes last year I'd sure noticed kicker speakers were easily twice as loud as competitors from the same car stereo head unit, might be good pairs to look at.

[tyger23]

Re: Modding the Lepai T2020A+

**Rant On**

I recently picked up two of these on the special, and I've looked over this thread and many others with regards on how to modify them.

Sure - improvements can be had. Perhaps the BIGGEST improvement is in the power supply. However, even that seems to have been mitigated by the new 3A supply shipping with these (if you're powering an 8-ohm load). A 4-ohm load should probably still receive an upgraded supply at 4 or 5A.

One of my issues with these amps is simply that people seem to want to pay $20 for an amp, put in $20 of work and get out $200 of sound. These little guys are great when pared with something like my Mariposa's (or stuff of similar price range), but they're horrible when you move up to anything decent in terms of the speaker world. Trying to pair this amp with something like the Continuum's, Speedsters, Stances, or even my Arias is like trying to put a Volkswagen engine in a Lamborghini. Sure it will go. It might even go fast. It might even sound good when it cruses past on Ocean Blvd. But, dude, try and press the pedal down and it just won't go.

On the two I got recently, the build quality is horrid. The leads coming from the power switch have cold solder joints on BOTH amplifiers, and one needed to be repaired after 2 uses. I may still look at improving things. Off the top of my head:

• I would change out C30 and C31 (the input caps) with high-quality 10uF non-polar electrolytic caps.
• Change out the two JRC 4558 op-amps for LM4562's. I need to check the supply voltage on these before wholly recommending that, but it should work. I'm sure they've added in a low-pass filter on at least one of those op-amps, and changing that value should also help.
• People should look at how the amp is mated to the heatsink. If it's not flush mounted (if it's kinked in any way), they should remedy that.

Unfortunately, the one BIG issue I have with these amps is the same big issue I have with ALL class-D designs - the output filter. ALL class-D designs have an output filter to change the "class-D" waveform on the outputs into something that looks much more like a "class-AB" output when a speaker load is connected. This has to be done to reduce radiated emissions to a point where the FCC, CE, EU, and other government regulatory agencies will allow them to ship.

These output filters, however, have to be designed to support one particular load. Generally, the loads attached to the amplifier will be 4-ohms or 8-ohms, but what do you do if you're the designer and you don't know what load is going to be connected?? Well, you pick one, and the end-user suffers the consequences if they don't connect up what the amp was designed for.

Basically - the output filter should be designed for around 30KHz. Just above the human hearing range, but low enough to provide enough attenuation at the class-D switching frequency (generally around 300KHz). This output filter is formed by the indicator and capacitor located on each leg of the amplifier, but it requires the load (R) to form the last part of the equation.

So, if the designer of the amp chooses to design and populate an L/C that forms a 30KHz LPF when a 4-ohm load is connected, the end-user will experience a roll-off around 12KHz when an 8-ohm load is connected. This is not good as it attenuates the high-end by as much as a dB or more, depending on the components selected.

Conversely, if the designer chooses to populate L/C values that form a 30KHz LPF when an 8-ohm load is connected, and the end-user connects a 4-ohm load, the amp will not be attenuating the switching frequency enough. This may cause all kinds of audible funkyness, affects the efficiency of the amplifier, and is all-around not a good thing.

Some manufacturers (like Apogee) recommended the designer populate L/C values assuming a 6-ohm load. This is a compromise between 4- and 8-ohm loads. Perfect for neither, but it avoids the worst of both.

So, what's an end-user to do? Well, if the plan on hooking one of these up to a fixed set of speakers and never changing them, then they should alter the output filter on the amplifier to match their speakers.

Alternatively, I'd personally recommend going with a class-AB design. Sure, it's larger and less efficient, but its less affected by an unknown or altering speaker load and, in general, sounds better than class-D designs when connected to mid-to-high end speakers. And they cost less per watt. Something like the AMP-100 with my mods is a great intro to modding and results in a much better sound.

Don't get me wrong - class D amps CAN sound great. I've spent the past 10 years designing with them, so I know what they can do. They're perfect for embedded environments like computers, TV's, bed-side radios, etc. Even car audio amps can sound great (where 4-ohms is almost ubiquitous). It's even possible to design a multi-pole output filter that can support many loads, but this costs a lot of money and doesn't get done on budget amps.

Buy these little guys and enjoy them for the budget amp they are. They're fabulous for $20. But when it comes to listening to your HI-FI, please - put a Lamborghini engine in that Gallardo.

**Rant Off**

[kevin007]

Re: Modding the Lepai T2020A+

Seems that by the time you spend all the time and money to modify a Lepai you could build something like this: http://classdaudio.com/amplifier-mod...amplifier.html for cheaper and it would most likely sound better since it is a higher quality amp to start with.

Although I must say I like my little Lepai 2020 I use on my desk at work. But I am not sure I am willing to drop $112.00 for the modded one above. I think I would go with something like the class d amp above before the modded lepai just for the cost issues alone.

What do you guys think?

Kevin

[SDLitz]

Re: Modding the Lepai T2020A+

I know this would be an expensive way to go but would P.E. part #120-500 ( 10-20V 5amp) be a suitable power supply upgrade?