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PostPosted: 20 Sep 2010, 18:29 
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Joined: 08 May 2009, 08:20
Posts: 918
Location: Duesseldorf, Germany
PCB Layout Images
Attachment:
TDA2050_BRD_Square Pads.GIF

Attachment:
TDA2050_BRD_Round Pads.GIF


List of Materials
Attachment:
List of Components.pdf

Have fun ;-).


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Tom.

Some of my projects: TDA2050 Chip Amp, the LM3886 Gainclone Thread and the Szekeres Headamp Thread.


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PostPosted: 21 Sep 2010, 11:22 
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Joined: 24 Jun 2010, 00:48
Posts: 788
Location: Christchurch, NZ
Hi guys!

I have put together all the components for the TDA 2050 on a single breadboard.
Some of the PS wiring needs to be completed.
Most of the parts were re-used from older projects so there is extremely little cost involved in building this amp. I have yet to get a case !

Before finalizing soldering , can you check to see if all the parts are ok ?

PS : 10,000uF 50V per channel, snubbed with 0.1uF MKP
25A 400V bridge rectifier
500VA transformer (18-0) , (18-0). 25V DC after rectification

Amp module : C5,C6 = 220uF used instead of 470uF on the positive/negative rail bypass cap
C2 = 22uF 50V Bipolar electrolytic
2R2 resistor is 10W wirewound crossover grade
1uF input capacitor is metallized polypropylene type, industrial grade 100V
0.1uF ceramic type used to snub the 220uF 50V electrolytic capacitor
All resistors carbon film.
0.47uF zobel network cap is ceramic type.
Single heatsink pulled from an old computer. Should be good for 75W.
Dimensions H X W X D ( 75mm X 60mm X 40mm) 25 Fins

If all is ok, I will start wiring ASAP ! :mrgreen: :thumbsup: :up:


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PostPosted: 21 Sep 2010, 16:37 
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Location: Duesseldorf, Germany
Hi Dinesh ;-)

Quote:
PS : 10,000uF 50V per channel, snubbed with 0.1uF MKP
25A 400V bridge rectifier
500VA transformer (18-0) , (18-0). 25V DC after rectification
OK.
Quote:
Amp module : C5,C6 = 220uF used instead of 470uF on the positive/negative rail bypass cap
C2 = 22uF 50V Bipolar electrolytic
2R2 resistor is 10W wirewound crossover grade
1uF input capacitor is metallized polypropylene type, industrial grade 100V
0.1uF ceramic type used to snub the 220uF 50V electrolytic capacitor
All resistors carbon film.
0.47uF zobel network cap is ceramic type.
Single heatsink pulled from an old computer. Should be good for 75W.
Dimensions H X W X D ( 75mm X 60mm X 40mm) 25 Fins
OK.

If possible, i would replace the "Zobel" cap with an MKP or MKS type (metallized poly). OK - ceramic caps are designed for
high frequency applications (what a zobel is for) but i wouldn't trust them at this point.

Are you sure that this yellow drops are ceramic capacitors? They heavily look like Tantalum electrolytic capacitors.
Please check this. Tantalum caps are polarized (+ and -)... They are OK for snubbing, but they will break down if they are
out of polarity.

You must isolate both TDA ICs from the heatsink. The IC tabs are at the V- potential.

Have fun ;-).

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Tom.

Some of my projects: TDA2050 Chip Amp, the LM3886 Gainclone Thread and the Szekeres Headamp Thread.


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PostPosted: 22 Sep 2010, 03:51 
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Joined: 24 Jun 2010, 00:48
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Location: Christchurch, NZ
Hi Tom,

I am heading down to the shop soon to pick up some stock of 0.1uF MKP's. Will replace those ceramics with MKP types on the zobel network. The small orange cap is actually a multi-layered ceramic cap. I will remove all of them and replace with the MKP's. Attached is also the pic of the small 0,1uF MKP caps which I plan to use throughout the amplifier.

Am also getting the required plastic insulating washers for the chips. :D


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PostPosted: 22 Sep 2010, 13:04 
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Location: Christchurch, NZ
Hi Tom,

Before I continue with the mains wiring, can you see if the following is ok ?

- Using 10 Ohm CL-60 mains rated NTC thermistor in series with the primary winding of the 500VA
transformer.

- What is the suitable mains fuse to use ? I am on a 240V, 50Hz mains line.
Would a 1.5A fuse be ok? I stocked up on 0.5A, 1A, 1.5A, 2A and 2.5A fuses.

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PostPosted: 23 Sep 2010, 09:00 
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Location: Christchurch, NZ
PS is working well with a 10Ohm NTC thermistor and 1.5A fuse connected in series with the primary winding of the transformer. I used some 3.5'' Vifa fullrange test speakers - 82dB sensitive and 8Ohm. Initial impressions : great highs. Very crisp top end and engaging sound. Heatsinks get quite hot when the fullranges are commanded to fill the room with sound. A proper review will be done later when the system is connected to my 94dB 2 ways.

So far so good. Very impressed with the amp.


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PostPosted: 23 Sep 2010, 11:44 
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Joined: 24 Jun 2010, 00:48
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Location: Christchurch, NZ
Hello !

The urge was too great. I connected the TDA amp to my large speakers. The feeling of the music was unlike anything I have heard. This amp excels so well at 3D imaging. Soundstaging is the largest of all my amps as well. Madeleine Peyroux's voice leapt out in between the speakers, and she appeared 3 feet in front of me when I was actually 4.5m at the listening spot. Seductive, upfront presentation without any harshness. Bass is unreal, never heard those kevlars drivers plumb the depth to 25Hz with such impact. I know it hit 25Hz cleanly because my bathroom door has a natural resonance of 25Hz which starts ratting when the subwoofer excites it. I have not turned my sub on in months ! All of this from a chip amp? what !??! :eek: :censored:
The bass control was too good in fact - though that is not a bad thing. It does sound a touch lean in the midbass, but deep bass is superb.

The overall music texture was light and fluffy. No part of the frequencies were enhanced, save for the midrange, which I find is fairly relaxed. (or perhaps all my other amps were fatiguing ? ). There is not a hint of aggressiveness or fatigue after listening for 3 hours - superb.

There are a few points worth noting:

1. Midbass and lower midrange is a touch lean. Midrange is very slightly recessed.
2. Highs are slightly darker than normal, cymbal transient attack is bested by Aussie Amps.
3. Tone is light and crisp.

Plus points :

1. Fantastic 3D placement. Image location is the best I have heard.
2. Superbly controlled bass.
3. Relaxed presentation - Good for late night listening.
4. Insane preformance for the price.
5. Unfront presentation.

Great stuff Tom. This amp is a keeper and a lovely addition to my collection. (I have one of each amp class now - Class A - SE, AB, D and finally a chip amp!!!) :up: It can do things that my other amps can't. :headphones:

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PostPosted: 23 Sep 2010, 12:19 
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Location: Winnipeg, CANADA
Hi Dinesh, chip amps are freakish in that they sound very good for something so simple and inexpensive.

Try rotating your heatsink 90 degrees (like you had in the earlier photos). This will promote better cooling as the heat will cause the air around the fins to rise.

Cheers

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PostPosted: 23 Sep 2010, 12:27 
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Oh yes!! Thanks for that. No wonder it was getting slightly warm with no source input.

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PostPosted: 23 Sep 2010, 16:50 
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Location: Duesseldorf, Germany
Hey,

that review sounds amazing :D.

Thanks for the applause, but it must say that 'ST Semicon' did this marvelous chip and circuit...
I had only sticked the stuff together and i also was surprised. I believe, one reason why this chip
can sound that well is the design of the power supply. I always stick with that and always say:
An amp is only as good as the supply. If you want a good amp - build a good supply!
That because a 'signal amplifier' is nothing else than a modulated power / voltage source.
Fast and accurate supplies = fast and accurate amps. That's the formula (IMO).

I'm very glad that you like your amp.

The NTC is OK. Usually i would tend to 100 Ohms, but with that very high inrush current a 10 Ohm NTC is also fine.
Keep an eye on the NTC. If it's 'stand alone' it will get very hot!

I have no idea if the fuse is OK.
Gio has a nice formula to calculate the inrush (recommended fuse value) somewhere on this site.
I can't remember where it was... Sry - usually i use the recommendations from the manufactures datasheet.
Yesterday, i've read that the inrush current often is 8 to 10 times higher than the primary 'open circuit voltage'.
Especially toroidal transformers have very high inrush currents because of their gapless topology.
EI laminated 'air core' trannies are more 'current friendly' on the primary side.

Dinesh, please don't drive the amp to the limit. The 25VDC (V+ / V-) is slightly above the limit (1 Volt)
but that wouldn't affect the amp or the speakers under normal conditions.

If you want to operate the TDA in the upper range, think about adding a loudspeaker protection.
The TDA has some built-in protections, but not against burning or against overloads...
You might go well up to 85% output power with your setup. Above it becomes critical (and nearly PA style).

A little but very effective protection could be adding a 2200uF (4700uF better Zout - IMO) / 35VDC output cap. Just in case...
That should actually not affect the sonic results you got now.

Have fun ;-).

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Tom.

Some of my projects: TDA2050 Chip Amp, the LM3886 Gainclone Thread and the Szekeres Headamp Thread.


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