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Old 22nd April 2010, 02:53 PM   #91
rhing is offline rhing  United States
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I received my Arjen Helder TA2020MkIII amp last weekend and assembled the connections a few days. For volume control, I tried a 50k SMD stepped attenuator. When I tried out the amp, the volume at the first volume level step is extremely loud and distorted. Even when the stepped attenuator is set to zero, I can faintly hear sound coming out. Thinking that maybe the stepped attenuator was faulty, I replaced it with a 50k Panasonic EVJ volume pot. I still get the same response.

Looking from the top of the PCB, the connections I've made are as follows:


O O O
R GND R Out R In

O O O

O O O
L GND L Out L In


I've wired volume pots and stepped attenuators in other amp projects before, but am I missing something here, or did I get a defective amp? Any help is greatly appreciated.
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Old 22nd April 2010, 10:12 PM   #92
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I have one here with a V2 pcb, and there are small tracks linking the "in" and wiper tracks on the bottom of the board. If you're wiring into the pcb you would need to cut those. Otherwise wire the pot external to the board and just connect wiper and ground from the pot to the pcb. The "in" connection on the pot coming directly from your source connector.
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Old 22nd April 2010, 11:02 PM   #93
rhing is offline rhing  United States
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Quote:
Originally Posted by gazzagazza View Post
I have one here with a V2 pcb, and there are small tracks linking the "in" and wiper tracks on the bottom of the board. If you're wiring into the pcb you would need to cut those. Otherwise wire the pot external to the board and just connect wiper and ground from the pot to the pcb. The "in" connection on the pot coming directly from your source connector.
gazzagazza,

Thanks for the tip. I might try wiring the pot directly from the RCA inputs and connect the wiper and ground connections to the board.

Thanks again.
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Old 23rd April 2010, 01:37 AM   #94
rhing is offline rhing  United States
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gazzagazza,

You were right! The board has the same traces connecting the input thru-holes with the output or wiper thru-holes. I just wired the input RCA connectors directly to the volume pot as you suggested. I didn't want to disconnect the traces in case I use this as a power amp for future use. Thanks again for the help. It's working fine now. Once I burn in the amp, I'll share my listening impressions.
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Old 23rd April 2010, 01:58 AM   #95
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Excellent!
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Old 30th April 2010, 08:26 AM   #96
vzon is offline vzon  United States
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Default Power supply suggestions

I have been playing with the 2020 triamps for a little while and what I did for the powersupply was get a 5 amp switching supply and hook it to a 1 farad capacitor usually used in car amps. big huge thing with a digital voltage readout. What I noticed when turning the volume up on the amps it would actually pull the voltage down on that big capacitor. But you get tons of bass. So since it was still draining the cap at high volumes I purchased two more capacitors like that for a total of 3 farads and put a 7 amp supply there to keep them charged. Now when I turn the volume up there is no voltage drop on the capacitor. So I am thinking those little tiny capacitors you guys are using on your power supplies is the main reason you dont get much bass. I get tons of bass. floor thumping heavy deep bass. I can get a 25 hz sine wave to show up on tests.
My system has two amps, one for the main speakers and one amp for the sub woofers and floor thumpers.
On the main amp I have two 23 inch flat panel speakers(closeouts at parts express), and planar tweeters and two 10 inchers in speaker boxes. lovely sound.
The sub amp has one 12 inch speaker and two floor thumpers and a small center channel speaker which I keep turned down. Music comes out of computer on seperate channels, also will be working on the back channels eventually with a third amp.
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Old 30th April 2010, 01:51 PM   #97
rhing is offline rhing  United States
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vzon,

Thanks for the tip. I'm not a car audio enthusiast, but this looks pretty interesting. Besides heavier bass, can you comment on any other improvements in the sound quality?

Thanks,
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Old 30th April 2010, 08:13 PM   #98
vzon is offline vzon  United States
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Quote:
Originally Posted by rhing View Post
vzon,

Thanks for the tip. I'm not a car audio enthusiast, but this looks pretty interesting. Besides heavier bass, can you comment on any other improvements in the sound quality?

Thanks,
I cant say for sure any other improvements. I did take some photos of the capacitors and another option for inside the Amplifier case. Here are the photos of the car caps hooked in parallel and the 7 amp power supply that keeps them fed, and that setup feeds 2 Lepai 2020 amps.

And also a photo of some ultra capacitors to show how small they are.
the three blue capacitors are 1 farad each but only 5.5 volts so you have to hook 3 in series to bring the voltage up to 16.5 volts. the capacitance is now 333,333 uf, which is over 100 times the value of the capacitor that is on the board inside the amp which is only 3300 uf.

Another point also. it takes 9 of the ultra capacitors hooked in series parallel to make teh equivalent capacity as one of those large car capacitors. Which a little moding one could fit 9 of the ultracapcitors into the amp case.

Any way these are some ways to beef up the power supplies of the Lepai 2020 running at 12 volts.
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File Type: jpg ultracapacitors.jpg (646.7 KB, 894 views)
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Old 13th September 2010, 06:50 PM   #99
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[QUOTE=Kitarist;2021684]Hi Guys!!!

I was searching for a nice TA2020 amp on ebay and i found out that there are like thousands of them now.

I would like to know which ones really shine in terms of quality and are the best for the price?[/QUOTE

Hi all. This is my first post here, spent quite a bit of time lurking and have just taken my first foray into DIY. I just put together one of Arjen Helder's MKIII TA2020's, I built it inside a 0.65 plastic lunchbox as I did not want to spend money until I knew it could out perform the off the shelf versions from the likes of Topping.

I started my love affair with T Amps nearly two years ago with a Trends TA 10.1, then moved on to two Topping TP-10 MKII's to Bi-Amp a pair of B&W's for my desktop system, I purchased a HLLY TAMP 90 for a bedroom system and finally a Topping TP21 for a bathroom system. So I am in a good position to help answer the original posters question, so IMHO in descending order of sound quality :-

Arjen's TA2020
Topping TP21
Topping TP-10 Trends TA 10.1 (joint third)
.
.
.
.
.
HLLY TAMP 90

You can fill in the gaps with all the stuff that one hopes has to be better than the HLLY, as quite frankly it's bloody awful. For off the shelf I like Topping, from what I have seen on forum postings they do take note of what modders are up to. It's interesting that Arjen has chosen to sell the Topping TP20 MKII as his off the shelf offering.

As for my first DIY project it will be coming out of the lunchbox and into a proper case along with one of Arjen's tube buffers. More than likely I will build another one but containing two MKIII TA2020's, to replace my current Bi-Amped Topping TP-10's.
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File Type: jpg TAMPLB2.jpg (152.3 KB, 656 views)
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Old 6th December 2010, 11:30 PM   #100
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Hi Vzon,

Have you checked that your SMPS is happy with that level of capacitance sitting on it's output? Hopefully all is fine, but you can't take it for granted that the SMPS is happy.

If you want better bass with these amps the MOST important thing to do is to replace the input coupling caps with bigger better ones. Assuming the input impedance in 20Kohms (my guess), The supplied 2.2uF caps will make the bass -3dB at 3.6Hz but phase issues will be present up to at least 36Hz. You need to double this capacitance for improved bass response - try 4.7uF as a common value. But remember the rule for caps in series: if your source has an output coupling cap this may also be rolling off the bass. Personally I would go with 8-10uF industrial polypropylene in oil input caps to minimise issues with source output caps.

Rhing, assuming the amp board input impedance is indeed around 20Kohm try a 10Kohm attenuator instead of the 50Kohm. Ideally you would want a passive attenuator to be a tenth of the impendance of your amp input, but going down to 2Kohm would place too much load on your sources output. 10Kohm should be fine (much better dynamics and bass than 50Kohm).
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