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Hifimediy T1 Alps TK2050 STA510 version 1.4 with Connexelectronics SMPS300R 28V 300W

Hifimediy T1 Alps TK2050 STA510 version 1.4 with Connexelectronics SMPS300R 28V 300W

First, about myself:
I am not an electronic expert, I am a mechanical engineer by profession, servicing machines used in semiconductor assembly.
I am a Filipino, residing in Singapore for 9 years now, looking for a good sounding system with decent power but on a budget.
I like doing diy's, not so much on electronics, but I'm certainly not shy to do one.:cool:

Second, about the project:
Our 5-hours-per-day-everyday-used-for-watching-TV, 150 Watts per channel, 10+ years old BMB (Japan) amplifier is about to give-up.
The sound just mutes everynow and then for about 5 seconds everytime and then sounds back again.:mad:
Sometimes I have to give it a hard tap on the side to get the sound back faster- hmm, looks like a loose connection inside.

That started my quest for a good sounding amp to replace it, so I googled, learned about Tripath based amps-that many have given high ratings. To give it a try, I bought a TA2020 amp made by Indeed, and it was able to drive our 200 watts/channel BMB speakers with good clean sound-it's great.
But the amp is set to it's maximum volume level (but no distortion)-good for our TV watching but not for our occasional karaoke singing, :rolleyes:hehe.

So I looked for a more powerful Tripath amp (>80 watts/channel) but all (complete-cased-amps) are about US$300- out of my budget.:(
In my search I read about this TK2050 amp designed by hifimediy and receiving good reviews.
I also learned about Connexelectronics power supplies, clean noiseless power, being sold here!
I reckon, I'm going to do some diy myself, hehe. So I bought the pair...till next...
Before I took the plunge, I have to review my objectives and reason for the decision:

Good sounding amp = good reviews

Budget = price and shipping = amp board and psu board shipped together further reduced the cost

Ease of assembly = pre-assembled amp and psu board = just connect, that's it!

Decent power = 100 watts per channel on 8 ohm speakers

Oh and yes, size! I happen to have an amp casing taken from an old Pioneer Reverberation Amp-that somebody threw away outside our block.

I picked it up, measured the inside dimension and its 180mm X 250mm. Just right!:o

Before I really really took the plunge, ;)hahaha, I started emailing hifimediy to get some advice on what is a good amp and psu pair in their line.

Steinar was quick to reply and recommended the T1 with 28V SMPS300R adjusted to 30V for my requirements.

The weather in Singapore is always warm the whole year, so Steinar recommended to run it at lower voltage, since I put up my concern for heat.

I am also planning to put a 12V centrifugal fan to run at 5V to quietly and constantly push out the hot air from inside the case.

I will have to test and see how hot the heatsink will get in my normal use.

I received the two boards via Hongkong post, and by the looks of it, they are in good condition.

I was able to prepare a wooden board to temporarily mount and test the T1 and psu.

I installed 2 SSR's (Solid State Relays), one for neutral and one for live AC, to soft start the amp.

The SSR's are from junk machine boards, and will be powered by a mini 12-0-12v smps (0.4 Amps) also taken from the junk board.

I also prepared templates made of cardboard to reduce my handling of the amp board while I prepare the temporary mounting and the final enclosure.

Less handling will reduce the risk of ESD damage.:rolleyes:

I mounted the boards and hooked all the wirings.

I prepared 2 wires with alligator clips at the ends, for my measurements of voltages, one red and one black wire.

I used a digital multimeter to first measure the voltage output of the connexelectronic SMPS300R.

It is at 28V right on the dot!:)

As recommended by Steinar, I need to adjust the voltage output of the SMPS to 30 V.

I turned the trimpot clockwise while monitoring the multimeter for the output voltage.

I hit the maximum mechanical limit of the trimpot but the voltage is just 29.5 V.

I tried a few times and it's really the highest voltage it can go.:(

In the end I just set the output voltage to 29 V.


By the way, can I set the SMPS to 29.5 V, without causing any future problems? e.g. parts failure?
Hi, good work!
29.5V is okay, no problem with that! The T1 can run on 24V-39V so it's ok down to 24V actually.
Keep us posted ! :)
It's been a while since my last log, I became very busy for the past weeks and so I wasn't able to finish my project as planned, but I will, let's continue...
Thanks Nick, I followed your advice and used the maximum voltage output I can set for the smps - 29.5V.

From the very first power on, the amp was already connected to the speakers, and I am not hearing any noise, hissing or humming sound from the speakers, I'm impressed!
Even when the vol-pot is maxed out, I just hear the familiar clicking sound of the relays when I power it on - zero noise even when I put my ear near the speakers.

I got my first sound, using my PSP as music source, playing that old Billy Ocean's songs, hehe.:o
But the sound is quite weak, even when the volume level of PSP and amplifier is at maximum.:confused:
I played a few minutes more, while checking the DC voltage at the spkr out, it fluctuates from -2.4 to +2.0 mV - ok I guess, but then I noticed the sound became louder and louder.
And when I connected it to my Tv system, the volume has to be turned down. The sound is just what I'm looking for, clean, not muffled, very clear, the bass-just the right thump for me, hehe.;)
But I noticed the heatsink gets hot, my estimate is at above 50°C, and that's after 1 hour of playing at a loud level. I think I have to force cooling air.:rolleyes:
I was able to fit the amp and accessories inside my intended casing.:o

I found a 5.8V 700mA psu which was an old Panasonic cellphone charger in my junk box - to power the SSR's and the centrifugal fan. The fan just rotates quietly at half it's normal speed to cool the STA510. I made a plastic air duct to funnel the hot air from around the heatsink out of the casing. The heatsink never had a chance to heat up even after playing really loud for half an hour, cool!:cool:

Here is the amplifier fully enclosed.

We are now using it everyday to watch TV and play music, for a month now. No problem.

Oh and yes, we used it to sing karaoke and the vocals are just stunning. Well it also depends on the singer, hehe.;)

So, did I achieve my objectives? I sure did.:o

Great sound on a budget -I spent below S$200.

Assembly - no hiccups.

Noise - no hiss, no humm, can't hear a thing.

A satisfying project, I'm just glad I started it.:cool:

oh, looks nice !! great job! And thanks for sharing your progress along the way :)
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