Hlly TA2020 Tweaks

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I only recently discovered the small T- class amps and after reading all the fantastic reviews I decided to buy a HLLY TA20 with the Tripath TA2020 chip. I haven't received it yet, but I'm curious what tweaks could be done on this board to make it sound even better.
Being a complete noob I would like some input from you guys before I take out my soldering iron. From what I understand replacing some caps and maybe even inductors to "air coil" type will give deepeer bass and smoother highs? I have attached the schematics of this board to double check if I got this right.

Replace C1 & C2 (input caps)? Originally blue rectangular "1u5K250" (according to the picture at hlly's website)
Replace C10 & C13 (bulk caps)? Originally 180uF/25V
Replace C26 & C27 (power caps)? Originally 2X 470uF/25V according to the schematics but 1X 2200uF/16V and a ?uF 400V +/-10% according to the picture at hlly´s website
Replace L1, L2, L3 and L4 @ 10uH with equivalent air core inductors

I was thinking of replacing C1 & C2 with Jantzen 1,5uF/400V MKP.
C10 & C13 with Panasonic FM 2200uF/16V
C26 & C27 no idea. What is the purpose of these and should I replace them? With what in that case?
L1 - L4 any improvements to go to air core?

What is your experience and do you have any suggestions or comments? Every input is much appreciated!

Best Regards


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I would be very interested in any information also because I bought this board about 3 months ago and I have been using it 15-20 hrs per week and I just love what it does unmodified. I just really want to know the mods that will make big differences and not trying to get that last 2-3% improvements.

I also am powering this amp with a 14.5v PS and notice a decent amount of "extra" power when compared to using just a 12v PS. I don't have a heat sink yet on the chip, but I have been "touch testing" the chip for the past couple of weeks and I really don't notice a temp hot enough that I can't continually keep my fingers applied to the chip. In other words it's still staying pretty cool.

I'm feeding the amp from a Mitsubishi preamp and just let the volume stay set at around 75% of max. When I really crank up the volume on the preamp (ears start to bleed), I can begin to hear some distortion, but even at fairly loud levels the distortion of this amp is not very high. I'm feeding speakers with efficiencies of 90 db and 92 db and there always seems to be enough power for these speakers. I tried feeding my Advent/1's and you can definitely tell these lower efficiency speakers just aren't comfortable with this particular lowered powered amp. I also have some speakers that are 101 db and this little amp really makes those speakers "sing". Also for me with these speakers you can tell the amp has a very low noise floor. Almost black - probably not the amp's fault, but preamp and other electrical devices nearby.
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From my experince with the same chip by other suppier, C26 is called buffer cap. It can be mod by replacing ity with hiher grade componen and higher value say 6800UF. It could improve basses.

Replacing input caps could also improve sonic and soundstage. I replaced these input caps with russian PIO K75-10 (2.2uF) and russian teflon FT-3 (0.1 uF) in parallel.

Thanks for the feedback guys!
I received the amp the other day and am enjoying the sound it produces "out of the box" powered by the supplied Samsung 12V, 4A. Connected it to a pair of Marantz LD20 DMS 2- way Mini Monitors with 89 db sensitivity and they fill up a 20 m2 room very well.
As I have a baby @ home playing at very high volumes is out of the question. I will get back as soon as I find time to tweak this amp.
@ chandm,

after reading some more regarding input caps imho you have a really really nice solution for the input! The Russian PIO caps would be my #1 choice, but unfortunately they will not fit into my small box. I will probably have to settle with some small MKP like the SCR or Jantzen which are easy and cheap to buy in Sweden. Any preferences here?

What do you think regarding the power/buffer caps. Would it be better to only replace C26 to 6800 uF (I found the Panasonic FK caps with interesting spec.) and keep the same capacitance (180 uF) on C10 & C13 for the airy and detailed treble? Or replace C10 & C13 with larger caps (only/as well) since they are closer to the chip? And what role dose C27 play?

I will vote for Jantzen for input caps (Jantzen Superior Z-Cap MKP or higher grade). You may read the review of Jantzen caps and SCR caps at this site: http://www.humblehomemadehifi.com/Cap.html.

The value of input caps should be 2.2 uF or you may experiment with other value up to 4.7 uF and judge yourself which value suited to your system and your ears.

From the schematic, I think C26 and C27 has the same function, they are power/buffer caps, so you may repace those caps with 3300 uF each. Panasonic FK is OK for this application, or you may try RIFA caps (more expensive??) But looking at the board, C27 is a small cap. So I gues just replace C26 with 6800 uF caps and leave C27 there. You may upgrade C10 and C13 with a better caps with the same value or higher value (470uF). Panasonic FM is OK for this application.

I realize this is an old thread but, I just received this Hlly board and have a few questions (for now):
- J1 is labeled 'head phone' but it's wired as an input. Is it mislabled or is my schematic reading that rusty? :)
- what is the sleep function (S1)?
- what is the mute function and how is it wired in?

Thank you, in advance.
Just stumbled across this thread myself - i'm also going to be upgrading a HLLY board soon. Not got the board itself yet, but i've sussed out all of the schematic so I know what my plan of attack is :)

J1 isn't wired properly at all, if you wanted a headphone jack. At the minute, it acts as a 'line out'. I'll be removing mine.

The Sleep function is like a 'standby', it puts the T2020 chip into low-power mode. I'm personally planning on just turning the power off with a power switch mounted on the front/back panel, so I will disable the sleep function.

The Mute function, errr, mutes the output. There's a jumper (J2) that you can plug a switch into to activate/deactivate this mode. Again, i'll disable it.

On the schematic, jumper J2 is used to toggle the auto-reset mode - if the chip is overloaded by trying to drive too loud, it will shut down and trigger its 'Fault' pin. This can be used to automatically reset the chip (instead of having to disconnect power, wait and reconnect it). The way to do this is to short out pins 2 and 3 on J2. If you do not want this auto-reset feature, then short out pins 1 and 2 - this will also disable the mute function.

If you're not using the mute and sleep functions, then you can remove the following components from the PCB: C28, R11, R3, C6, S1. You will need to add a wire link where C6 used to be in order to ground the sleep pin (don't do this and it will float, and the TA2020 will always be in sleep mode).

If you don't want the overload indicator LED either, you can also remove R7, D9 and Q1.

As for previous posts, use a single large electrolytic cap in C26 (i'm using a 6800uF 25V), and put a small film cap in at C27, like a 100nF WIMA. This will help to decouple the big electolytic cap and reduce HF supply noise.

As well as lots of cap upgrades, I will also be replacing R2,4,5,6 with some decent makes of resistor, seeing as these are in the signal path (well, two of them are anyway, and the other two form a potential divider for the op-amps inside the TA2020).

Anybody else still building/modifying their boards? Let me know how you get on.
Just stumbled across this thread myself - i'm also going to be upgrading a HLLY board soon. ...
seanjacobs, sorry SO late in thanking you for your reply.
I finished the amp I was building and sounds very good as-is.
I am using an xBox power supply now, it is ridiculously overbuilt but it is (as far as I can tell) fixed at 12v.
I'm still trying to figure out a good way to give me a line level sub out.
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