Lepai T-Amp with TA2020

[htgeek]

care to share what inductors you replaced with and how u replaced them??

Same question here.

It seems that everybody replaces them with toroidal 10uH 3A inductors, but don't know if exists any other requirement, as I see that there are inductors with more features (choke frequency, etc.)…

I have seen these on ebay http://www.ebay.es/itm/260894512078 and http://www.ebay.es/itm/260512722675 The first look nicer, but the second is cheaper, more inductors, and more amps capable…

Any recommendations here?

 

[frasco]

I have the second ones. Haven't built my amp yet and don't have anything to compare with for that matter, so no recommendations sorry..

 

[Calamaro]

Tripath definitely suggests toroidal inductors with iron-powder cores as shielded bobbin construction is not as effective for EMI containment.
Powdered iron is regarded to have an higher Q and in our case this is a premium.

http://www.osoelectronics.com/downloads/Winding and Using Toroids.pdf

For the smallest toroid suggested by Tripath, Micrometals code is T60-2. This is the toroid provided by 41Hz.com with their kits and require 39 turns of 0.5mm magnet wire; I think Arjien Helder too use them: try to count the turns

(A bigger one -with better specs- could be "T68-2 wound with 44 turns of 22AWG wire" according to Tripath technical informations).

Anyway, we need

10mH
3A
frequency higher than 1 MHZ
coil with high Q and
low saturation at high frequency

Your first option is definitely very good (the one from HelderHifi).

ps. how nice to see this thread still alive... a couple of years ago I had fun and really enjoyed this little amazing amp bypassing op amp and tone control but it seems that pcb now is a different one

http://www.diyaudio.com/forums/class-d/90500-lepai-t-amp-ta2020-27.html#post1838046

http://www.diyaudio.com/forums/class-d/90500-lepai-t-amp-ta2020-31.html#post1841106

 

[frasco]

First link doesn't work.

edit: You meant this one? http://oldradios.co.nz/downloads/Winding and Using Toroids.pdf

 

[Calamaro]

Sorry, it was an old link and I didn't check it
Yes this is the paper

http://oldradios.co.nz/downloads/Winding and Using Toroids.pdf

 

[Virpz]

care to share what inductors you replaced with and how u replaced them??

Hello sorry for the late awsner.

I replaced with TDK SLF12565T-100M4R8 that I had already purchased. They are classified as power inductors but they did a great job on replacing the Lepai ones. 20 inductors for 10 bucks on ebay. Digi key sells one for 2.13. I can't tell you the frequency of those because I was unable to find that info:

Cheap
10uH
Rated 4.8a
shielded

They are much better than the lepai stock but chokes with iron powder cores like the already mentioned t60-2 might be better since they are suggested by tripath and used on their reference boards.

After alot of reading on the subject I think it is up to your taste as you can see here . After testing all the recommended and suitable types this guy went for the non obvious option.

[]'s

 

[htgeek]

Tripath definitely suggests toroidal inductors with iron-powder cores as shielded bobbin construction is not as effective for EMI containment.
Powdered iron is regarded to have an higher Q and in our case this is a premium.

http://www.osoelectronics.com/downloads/Winding and Using Toroids.pdf

For the smallest toroid suggested by Tripath, Micrometals code is T60-2. This is the toroid provided by 41Hz.com with their kits and require 39 turns of 0.5mm magnet wire; I think Arjien Helder too use them: try to count the turns

(A bigger one -with better specs- could be "T68-2 wound with 44 turns of 22AWG wire" according to Tripath technical informations).

Anyway, we need

10mH
3A
frequency higher than 1 MHZ
coil with high Q and
low saturation at high frequency

Your first option is definitely very good (the one from HelderHifi).

ps. how nice to see this thread still alive... a couple of years ago I had fun and really enjoyed this little amazing amp bypassing op amp and tone control but it seems that pcb now is a different one

http://www.diyaudio.com/forums/class-d/90500-lepai-t-amp-ta2020-27.html#post1838046

http://www.diyaudio.com/forums/class-d/90500-lepai-t-amp-ta2020-31.html#post1841106

Thanks a lot, very interesting the link about toroids.

I will buy them and give a try... (I will end spending more money in improvements than the cost of the amplifier XD).

I think that with this mod, bypass tone, changing decoupling capacitors and a bigger power input capacitor will be enough, or at least I hope so...

 

[frasco]

Btw here's an interesting little study on inductor placement: http://www.troelsgravesen.dk/coils.htm

 

[Calamaro]

Thanks a lot, very interesting the link about toroids.

I will buy them and give a try... (I will end spending more money in improvements than the cost of the amplifier XD).

I think that with this mod, bypass tone, changing decoupling capacitors and a bigger power input capacitor will be enough, or at least I hope so...

I agree, this will be definitely enough for this pcb. Honestly speaking if you want more choose a better pcb. Maybe you could replace the volume pot with a better one.

PS. please keep in mind that the best improvement will come just from listening to the amp: it need 100 hours burning.

 

[st33n]

I keep getting a "humm" on my amp. It a Helder TA2020mk3. Any tips? Not sure how to ground it or anything..

 

[vmed_cha_gr]

Hi Everyone !
Got mine 2 days ago, it is one of the latest versions. Changed all electrolytics with panasonic FC. Bypassed the pre stage with 2 thetta MKP 2.2uf & added 2 extra rca input plugs, but kept the pre stage for any future needs (if you wanna connect a cd player). Used a 6.3A /18v power supply with a step down dc to dc converter adjusted at the exact 12v. It is an smd board but components are easy to extract. Pin No 18 is still connected to a kind of stupid protection circuit (looks like a resistor with a transistor) but i just cut the trace and left it open. By the way the 3300uf/16v electrolytic at the power supply stage was a used one & leaking (what a Chinese quality check ?) so you better change that and remove the inductor or sort it.
First audition was very impressive. I'm waiting for the inductors to arrive to complete the DIY. Money spend for everything (inductors included) 18euros (with post expenses) for the Lepai amp & about another 12euros for the rest.
Seriously ! I can't believe my ears. This is one of the best inexpensive little amps I've ever heard (but you have to do the mods).
Vassilis

 

[kristleifur]

Used a 6.3A /18v power supply with a step down dc to dc converter adjusted at the exact 12v.

It is an smd board but components are easy to extract.

This is one of the best inexpensive little amps I've ever heard (but you have to do the mods).

Tripath is amazing isn't it! Enjoy the music.

Regarding power supply voltage - the TA2020 chip can take up to 14.6V. That's a difference of about 1.7dB headroom. It's not super important, but if you can push the voltage higher than 12V "for free" on your converter, then it's worth doing — IF the other components can handle it (at least a question of the capacitors' voltage rating).

And I must say, sorry for the preaching but I have to - that I find SMD components much easier to extract than through-hole (And soldering them easier too - smd is harder at first, but after reading a little up on techinque and getting the right tools, SMD is actually wayyyy faster and easier!)

 

[Franfj]

Tripath is amazing isn't it! Enjoy the music.

Regarding power supply voltage - the TA2020 chip can take up to 14.6V. That's a difference of about 1.7dB headroom. It's not super important, but if you can push the voltage higher than 12V "for free" on your converter, then it's worth doing — IF the other components can handle it (at least a question of the capacitors' voltage rating).

And I must say, sorry for the preaching but I have to - that I find SMD components much easier to extract than through-hole (And soldering them easier too - smd is harder at first, but after reading a little up on techinque and getting the right tools, SMD is actually wayyyy faster and easier!)

The previous version at least has a Zener diode to "protect" against more than 13.5v, so isn't recommended going with more than this, some people say that could damage the board because of the lack of protection in the outputs.

On mine's now I have the decoupling capacitors changed by MKP 2.2uf (the ones before were 3.3uf although on the board is clearly printed 2.2, WTF??), and the sound improved a so much that I can't believe that.

Also have added another cap parallel on the power input, so now I have the 3300uf + 6800uf, and the power led doesn't blink like before.

 

[Franfj]

Just one hint if anyone has the same problem as me, the amp started to make constant pops after changing caps. It doesn't enter in fault mode, just overload.

What happened is that the resin from the solder wire created some kind of conductor between some tracks. After a lot of time soldering and desoldering, with random success (some times pops on left channel, others on the right ) cleaning the pcb with alcohol solved the problem

 

[pkozul]

Toroidal inductors

Hi all,

Just saw these go up on eBay yesterday...

Coils sets for Tripath TA2020 20W Class-T Digital Audio Amp upgrade. | eBay

I asked the seller for the specs, and he replied with this info:

"Hello, this is 10uH, 5A. & very low resistant. We test all with other LCR Meter before ship."

Seems like it's worth a shot, eh? Cheapest toroid option I have seen so far.

Cheers,
Pete

 

[vmed_cha_gr]

another one !

Well I just bought these : http://www.ebay.ie/itm/260512722675?ssPageName=STRK:MEWNX:IT&_trksid=p3984.m1439.l2649#ht_607wt_833 but i'm still waiting for post to arrive.
The ones you are looking should be fine. If you buy & test them just share your opinion with us.

Hi all,

Just saw these go up on eBay yesterday...

Coils sets for Tripath TA2020 20W Class-T Digital Audio Amp upgrade. | eBay

I asked the seller for the specs, and he replied with this info:

"Hello, this is 10uH, 5A. & very low resistant. We test all with other LCR Meter before ship."

Seems like it's worth a shot, eh? Cheapest toroid option I have seen so far.

Cheers,
Pete

 

[Virpz]

I did the last mods on m lepai's lp2020a+. Looking at the output stage noticed that there is a smd cap just after the inductors. Well I have no clue what they intended to anchieve with that cap there but my guess is that it is their EMI output filter and they placed it right there before the output caps. Also the zobel cap on mine had one 0.47uF cap instead of 0.22uF. there we go:

I used 10000pf 5% polystyrenes that I had around for C40 but you can use multilayer ceramics.
If you're going to use it as power amp you better replace R8 and R10 with 22k or 39K low noise resistor. Much better now .

On one of my units I did the bypass and added a volume pot following Pano mod for sonic impact. Great reading there.
If you want add the volume pot after you did the bypass on Lepai Lp2020A+ you should look at the image bellow.

 

[Franfj]

One doubt, which one will be better?

ALPS RK14

An externally hosted image should be here but it was not working when we last tested it.

ALPS RK27

An externally hosted image should be here but it was not working when we last tested it.

The first one is cheaper (about half the price of the second). Everybody uses the classical blue ALPS, but they both seem tho have the same specifications on the ALPS website, plus the first is smaller and looks like a newer model…

 

[Virpz]

One doubt, which one will be better?

ALPS RK14

An externally hosted image should be here but it was not working when we last tested it.

ALPS RK27

An externally hosted image should be here but it was not working when we last tested it.

The first one is cheaper (about half the price of the second). Everybody uses the classical blue ALPS, but they both seem tho have the same specifications on the ALPS website, plus the first is smaller and looks like a newer model…

You can stick with the one that came with the lepai, it works just fine. Anyway if you think the lepai is worth of an alps pot you may get this one

 

[Franfj]

The one about what I am taking is this http://www.ebay.es/itm/170683788782#ht_1944wt_1117 only 7$

My Lepai volume potentiometer is a piece of crap, its not centered, makes noise using it, and the knob moves in the vertical axis by 1mm u_u

But thinking about it, I think that better will remove one of the tone potentiometers and replace the volume by one of them.

Another question, what do you think about wood enclosures?, I'm thinking about making a simple one, just to improve the amp appearance. Will be needed to make some kind of metallic cover for the amp to avoid EMI?