Modding the Lepai T2020A+

[vlad335]

Re: Modding the Lepai T2020A+

I upgraded one of these amps with the ebay PSU and caps and it sounds fantastic. REALLY REALLY GOOD! Actually, performed the mods on two amps and unfortunately bricked the first one somehow. On the second attempt I just replaced the 6 output caps and the big one. My soldering sucked when I first tried this but i am better now.

Anyway... I want to do this again to another Lepai. However, it seems the 6 red caps are out of stock at mouser with a 15 week lead time. These are listed as 63V .47uf +80/-20%. Is there a suitable replacement on the mouser site? More expensive doesnt matter just as long as they work and are an upgrade.

[Palos]

Re: Modding the Lepai T2020A+

Has anyone ever changed the T2020 chip? I think mine might but shut, I'm not getting and output volume. Any ideas on how to test it?

[jjminch]

Re: Modding the Lepai T2020A+

Hello,

I think this mod threat is great, but a little above my skill set. I plan on upgrading the power supply to an eBay LCD brick and calling it a day for now.

However I would like to tap into the unit for some 5v power. Is there enough in there to run an iPhone charger (1amp) and 3-4 small LEDs?

If so, how could I do this? Solder wires to the power input jack terminal inside the amp?

[RINNAV]

Re: Modding the Lepai T2020A+

Interesting... It looks like someone has been watching this thread.

http://positive-feedback.com/Issue69/lepai.htm

But for the price of this "upgrade", I am sure you can follow this thread and come out a lot cheaper...

http://positive-feedback.com/Issue69/lepai.htm

[danvee]

Re: Modding the Lepai T2020A+

At the risk of reviving a Zombie thread -

The 6 .47uf caps in the output: any risk or damage by replacing them with 1uf?

[tinkertoys]

Re: Modding the Lepai T2020A+

old thread nowadays but glad I'd found it.. did all 3 of my 2020A's a couple days ago, a definite improvement over stock. the first one got everything specified, the next two got 4 outta 6 of the rear coupling caps, the two not changed out dont have the extra hole for a larger cap and are much harder to get at anyway. havent noticed any difference between the first one done with all 6 and the two after that only got the easier 4 replaced back there.

Lepai did make some minor changes to the board, you might need 2 of the 470 caps and 1 of the 220's up front, so just buy both in pairs to be sure you have what you'll need.

with the stock 3A power supply, much better bass but it still cut out at about 5/8 or 2/3 volume on songs with heavier bass. with a 5A supply it'll go past 3/4, start distorting like mad nearing 7/8 volume, and go full volume too not cutting out. I'm going to guess it's near doubled the usable power, was 8.3w before distortion hit 1% when stock (an audio guys honest youtube review), I wouldnt doubt 12-13 watts now before distortion gets mean, is a BIG improvement over bone stock!

soldering: I dont have anything fancy, just a big old weller soldering gun. I tinned the leads of the caps a little heavy and planted them in from the backside, letting the tinned stuff take care of joints at the topside, just in case it IS needed to have connections on both sides of it. didnt have any problems going about it this way with all 3 amps.

[deewalk25]

Re: Modding the Lepai T2020A+

old thread nowadays but glad I'd found it.. did all 3 of my 2020A's a couple days ago, a definite improvement over stock. the first one got everything specified, the next two got 4 outta 6 of the rear coupling caps, the two not changed out dont have the extra hole for a larger cap and are much harder to get at anyway. havent noticed any difference between the first one done with all 6 and the two after that only got the easier 4 replaced back there.

Lepai did make some minor changes to the board, you might need 2 of the 470 caps and 1 of the 220's up front, so just buy both in pairs to be sure you have what you'll need.

with the stock 3A power supply, much better bass but it still cut out at about 5/8 or 2/3 volume on songs with heavier bass. with a 5A supply it'll go past 3/4, start distorting like mad nearing 7/8 volume, and go full volume too not cutting out. I'm going to guess it's near doubled the usable power, was 8.3w before distortion hit 1% when stock (an audio guys honest youtube review), I wouldnt doubt 12-13 watts now before distortion gets mean, is a BIG improvement over bone stock!

soldering: I dont have anything fancy, just a big old weller soldering gun. I tinned the leads of the caps a little heavy and planted them in from the backside, letting the tinned stuff take care of joints at the topside, just in case it IS needed to have connections on both sides of it. didnt have any problems going about it this way with all 3 amps.

Do you know the easiest way to get rid of the speaker protection so when i turn it up to hear it over my bike pipes it wont cut out?

[Sydney]

Re: Modding the Lepai T2020A+

On a related Note: Ron Tipton was having 2020A shutdown: He drilled six .3" diameter holes on each side of the enclosure and added a cooling fan.

[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?

[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

[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**

[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.

[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.

[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

[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.