Lepai Tripath LP-2020A+ mini Amp dissected

Excellent. But, I've been told that to be 100% secure, I should go with a full Cranial Lobectomy, followed by the insertion of a single-ended 2A3, double shielded with perforated uMetal and Ultraperm. I'm seeing more and more people around here doing this mod, so that's probably the way I'll go. It's hell on one's verbal skills and you have to nap during power failures, but at least I'll be a free man!

-k
 
I was originally only trying to add some factual information to the thread. But, it seems like some people are too smart to learn, and too clever to be fooled by the Audio Illuminati....

Bless their oxygen-free tinfoil hats and OPA627 ELF detectors.

-k

Facts, schmacts! Forget all those fancy degrees you hold, the patents, the years of experience in the industry. All you really need is to head out to the nearest high end audio emporium, and listen! You'll be an audio expert in no time, extolling the virtues of liquid speakers, of night-and-day differences between cables, of $20K DACs! You will be respected and admired for your great insight! Just do it, Ken!
 
For those planning on ditching the 2A included AC adapter in favor of a 5A supply from Goodwill (or elsewhere), Parts Express has the Lepai LP-2020A+ for $19.88 without power supply. I may have to break down and include one in my next order to see what all the fuss is about.
 
For those planning on ditching the 2A included AC adapter in favor of a 5A supply from Goodwill (or elsewhere), Parts Express has the Lepai LP-2020A+ for $19.88 without power supply. I may have to break down and include one in my next order to see what all the fuss is about.

I found a 6A power supply on eBay for $7.00. It powers my Lepai just fine :)
 
This question is for Ken Kantor, if he ever returns to this thread. :D

I have a question about the capacitor for the charge pump switching pins 31 and 32.

The data sheet for this device does not give a lot of details about these pins other than they operate at 300Khz and to use a .1uF cap.

I was reading up on other charge pump devices trying to glean some information about what kind of capacitor to use in this type of ,"flying capacitor", location.

Most of the data sheets recommended a very low ESR capacitor and also using ceramic in many cases.

I was wondering if this Tri-Path 2020-20 requires the same type of cap or if it even matters at all. I found two caps that I think will fit the requirements. I will go with the cheaper one if it makes no difference, not that they are that expensive in the first place.

It would be nice to hear from someone who has experience designing with these chips.

Thanks for any help you can give.

Tri-Path data sheet
http://www.kafka.elektroda.eu/pdf/tripath/TA2020.pdf

C9, on Lepai) "Flying Capacitor" ceramic option.
http://www.mouser.com/ProductDetail...=sGAEpiMZZMuAYrNc52CMZKQW5e6risl1KbnDAtO5T1k=

Cheaper polyester option. The impedance graph @ 300Khz looks to be about 1 or 2 ohms.
http://www.mouser.com/ProductDetail...GAEpiMZZMv1cc3ydrPrF0%2bjlB8SXIRuNETHDW9yLSA=

p.s. Why do I want to replace the caps?

1) My two Lepai amps came with what looks like a hodgepodge of capacitors that probably should have been thrown in the recycle bin.

2) Convert the outputs for an 8ohm load (.22uF caps), 4 ohm load .47uF caps seem to be the stock default.

3) Practice soldering on my cheap stuff so I don't mess up the stuff I care about. :thmbsp:
 
This question is for Ken Kantor, if he ever returns to this thread. :D

I have a question about the capacitor for the charge pump switching pins 31 and 32.

The data sheet for this device does not give a lot of details about these pins other than they operate at 300Khz and to use a .1uF cap.

I was reading up on other charge pump devices trying to glean some information about what kind of capacitor to use in this type of ,"flying capacitor", location.

Most of the data sheets recommended a very low ESR capacitor and also using ceramic in many cases.

I was wondering if this Tri-Path 2020-20 requires the same type of cap or if it even matters at all. I found two caps that I think will fit the requirements. I will go with the cheaper one if it makes no difference, not that they are that expensive in the first place.

It would be nice to hear from someone who has experience designing with these chips.

Thanks for any help you can give.

Tri-Path data sheet
http://www.kafka.elektroda.eu/pdf/tripath/TA2020.pdf

C9, on Lepai) "Flying Capacitor" ceramic option.
http://www.mouser.com/ProductDetail...=sGAEpiMZZMuAYrNc52CMZKQW5e6risl1KbnDAtO5T1k=

Cheaper polyester option. The impedance graph @ 300Khz looks to be about 1 or 2 ohms.
http://www.mouser.com/ProductDetail...GAEpiMZZMv1cc3ydrPrF0%2bjlB8SXIRuNETHDW9yLSA=

p.s. Why do I want to replace the caps?

1) My two Lepai amps came with what looks like a hodgepodge of capacitors that probably should have been thrown in the recycle bin.

2) Convert the outputs for an 8ohm load (.22uF caps), 4 ohm load .47uF caps seem to be the stock default.

3) Practice soldering on my cheap stuff so I don't mess up the stuff I care about. :thmbsp:


A charge pump is used to conveniently generate a low current supply voltage above the level of V+. In our case, this voltage is used to bias the output stage so it can be run all the way up to the rail.

The main thing you want in a charge pump cap is low inductance and, to a lesser extent, low ESR. (In this regard, a charge pump cap requirements are similar to those of a supply bypass cap.) While I don't know the inductance of your suggested cap, Ls is not generally a forte' of that style of cap. The flip side of this is that the inherent limitations of ceramics, such as tempco and linearity, are mostly immaterial for charge pumps. Meanwhile, because 300KHz is not a super high frequency, there is a good chance your cap will work, (possibly at a slightly reduced pump voltage.)

Bottom Line: It should be easy to get decent 0.1uF ceramics for less than a quarter. That's what I would use. Alternatively, you could try your stacked film cap, which will probably work.

Hope this helps!

-k
 
Last edited:
A charge pump is used to conveniently generate a low current supply voltage above the level of V+. In our case, this voltage is used to bias the output stage so it can be run all the way up to the rail.

The main thing you want in a charge pump cap is low inductance and, to a lesser extent, low ESR. (In this regard, a charge pump cap requirements are similar to those of a supply bypass cap.) While I don't know the inductance of your suggested cap, Ls is not generally a forte' of that style of cap. The flip side of this is that the inherent limitations of ceramics, such as tempco and linearity, are mostly immaterial for charge pumps. Meanwhile, because 300KHz is not a super high frequency, there is a good chance your cap will work, (possibly at a slightly reduced pump voltage.)

Bottom Line: It should be easy to get decent 0.1uF ceramics for less than a quarter. That's what I would use. Alternatively, you could try your stacked film cap, which will probably work.

Hope this helps!

-k

Thanks Ken, That's very helpful.

Now I have to figure something else out too. I was looking over this thing and found they used 1uF electrolytic cap instead of the .1uF MLCC cap called out in the documentation for the bias cap on pin 14. :screwy:

http://www.profusionplc.com/images/data sheets/eb-ta2020.pdf
 
Last edited:
Thanks Ken, That's very helpful.

Now I have to figure something else out too. I was looking over this thing and found they used 1uF electrolytic cap instead of the .1uF MLCC cap called out in the documentation for the bias cap on pin 14. :screwy:

http://www.profusionplc.com/images/data sheets/eb-ta2020.pdf


The 1uF lytic is fine. The .1uF MLCC would be smaller and easier to use in an auto-insert machine, but possibly more expensive. I wouldn't sweat it.

-k
 
The 1uF lytic is fine. The .1uF MLCC would be smaller and easier to use in an auto-insert machine, but possibly more expensive. I wouldn't sweat it.

-k

O.K., good to know.

I just found it kind of odd that they use this one 1uF lytic when they seemed to get the other .1uF MLCC caps put in correctly.

Thanks for the clarification. :thmbsp:
 
Cheesy ain't cool? And here I've been thinking all these years that I was a cool dude. Another delusion shattered. :tears:
 
Last edited:
power supply

just got my lp-2020 and I'm diggin' it! I want to buy a couple more and start doing some mods. However, I can't find any good write ups or information on how to use a power supply like this with the lp-2020, anyone have any direction and/or pics of this done?
 
These are nice! Hearing how good Tripath sounds still amazes me

I built a boom box and used an AMP6 amp from www.41hz.com. This is the same guts as what you have in this Lepai amp. The same 25w per channel out of the same Tripath chip. Amazing how good this sounds.

The AMP6 is smaller as the amp is basically stripped of Volume control, Bass, Treble, Balance etc.

I built a boom box that is basically an MP3 player.. It just uses the volume control on the MP3, Iphone, droid etc.

I have it with a 12V power supply and a battery.. A 3 pole toggle to go from Battery/120 to 12V/OFF.

Here is the build.. The 120 > 12V converter, the AMP and a nice power supply capacitor in the middle with the speaker crossovers on the sides.

SecondWeekend2.jpg


Tiny little amp:
amp6_HS2.jpg


Here is the finished boom box. Plug one end of the MP3 player in the front and flip the red toggle up for 120 Wall outlet power or down for the 12 battery in the thing.
BoomBox2011.jpg


People listen and are amazed when they see the amp the size of a pack of bubble gum
 
Sorry if my last post was a deviation from the topic... Just intended to support the 25W per channel amp you are discussing.

Good speaker pairing for DIY-ers... Parts Express has a project called "Encore Speakers" that run some of the higher end Dayton drivers. These are in the boom box I built. Excellent book shelf speakers
 
Wow this is a great resource. I just picked up a lepai 2020A+ to fiddle with. One mod I haven't seen that I am considering is to turn down the gain on the tripath 2020, since I will be using it with 8 ohm speakers and the amp output is garbage above 6 to 8 watts or so, in this case. Would best way be just using smaller values for the two Rf resistors?
 
Wow this is a great resource. I just picked up a lepai 2020A+ to fiddle with. One mod I haven't seen that I am considering is to turn down the gain on the tripath 2020, since I will be using it with 8 ohm speakers and the amp output is garbage above 6 to 8 watts or so, in this case. Would best way be just using smaller values for the two Rf resistors?

You have to be careful when dropping the gain by changing the feedback... this can sometimes lead to instability.

What is the gain of the original circuit, and what do you want to change it to?

-k
 
Wow this is a great resource. I just picked up a lepai 2020A+ to fiddle with. One mod I haven't seen that I am considering is to turn down the gain on the tripath 2020, since I will be using it with 8 ohm speakers and the amp output is garbage above 6 to 8 watts or so, in this case. Would best way be just using smaller values for the two Rf resistors?

If you want to run 8 Ohm speakers you should change the output caps C0 from .47uF to .22uF. Look at page 5.

Gain is discussed on page 9.

http://www.e-ele.net/DataSheet/TA2020.pdf

Other info

http://www.profusionplc.com/images/data sheets/eb-ta2020.pdf
 
Back
Top Bottom