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Old 2nd September 2012, 05:16 PM   #21
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The TDA2050 and LM1875 might show similar performance when the in/out signals are differentiated.
But when I use exactly the same system and identical pc boards for either chip they do sound different ! How , I don't know. But the difference is very audible and it isn't due to frequency response for sure !

Doesn't matter. Just pick your poison and be happy. Both are nice.

For a 5.1 channel amp maybe a 250 VA trafo is a minimum . If I were building a 5.1 system I'd keep a separate winding (or separate trafo ) for the bass channel.
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Last edited by ashok; 2nd September 2012 at 05:21 PM.
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Old 2nd September 2012, 06:36 PM   #22
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I have never run either at full blast, but have them both with different board topologies and with my tin ear, they do kind of sound the same at non-ear bleeding levels out of mediocre speakers. I do like the LM1875 probably because of the more simple layout.

I think that the term pick you poison is about right for this situation.
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Old 2nd September 2012, 06:44 PM   #23
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Quote:
Originally Posted by ashok View Post
For a 5.1 channel amp maybe a 250 VA trafo is a minimum . If I were building a 5.1 system I'd keep a separate winding (or separate trafo ) for the bass channel.
I recently repaired a 5.1 system with 6 pcs TDA2030 and power was only 100VA transformer. Audio system manufacturer was right, because, as I said in the article below:
Surse de alimentare liniare pentru amplificatoare audio - calcul, teorie, concluzii - Surse de alimentare - Tehnium Azi - Articole (Articles) - Comunitatea Tehnium Azi
if you put an audio amplifier to reproduce the increasingly frequent high audio spectrum, so less bass, then filtering capacitors can provide excess power and no need to size the transformer as it is done routinely. So, in this case, one 100VA transformer may be a good choice and for 6 pcs. TDA2050, 200VA transformer may be good choice. You do not need 250VA.
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Last edited by donpetru; 2nd September 2012 at 06:48 PM.
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Old 2nd September 2012, 06:48 PM   #24
AndrewT is offline AndrewT  Scotland
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6 channels of Power Amplifier on a single 100VA transformer.
And you believe them !
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Old 2nd September 2012, 06:50 PM   #25
johnr66 is offline johnr66  United States
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I was speaking of National from 20-30 years ago. It is the stuff I read, not really my personal opinion.

For anyone interested, Here is the link to the LM383 from the chip's designers site. LM383
Check his other work out also...

In his words, "But it is humorous when the TDA2002 is often referred to
as a replacement for the LM383. As a matter of fact, the
LM383 is really a reverse engineering of the TDA2002. Credit
should be given to the design engineer Bruno Murari who was
working for SGS at the time. He was the one who came up with
a way to do an automotive power amplifier using only five pins."

I see the "non differential pair" type design used on a lot of SGS chip amps. National adopted to their LM383. I should note that the TDA2030,40,50 series uses a diff pair at the input.
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Old 2nd September 2012, 06:57 PM   #26
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Quote:
Originally Posted by AndrewT View Post
6 channels of Power Amplifier on a single 100VA transformer.
And you believe them !
Andrew, at first I did not believe what I saw but I tested the audio system and they were right because is 5.1 system. Well, if you try to attack the audio system with bass on all 7 channels directly on inputs TDA's, when 100VA was little, but as it was sized audio system, with all circuits for a 5.1 system, then 100VA transformer was sufficient for those 7pcs. TDA 2030.

Warning, I mean the 7 pieces TDA2030, not TDA2050.

Later edit: I corrected above, it was 7 pieces, because on the sixth channel, subwoofer, there were two TDA2030 in bridge.
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Last edited by donpetru; 2nd September 2012 at 07:08 PM.
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Old 2nd September 2012, 07:13 PM   #27
fakeout is offline fakeout  Canada
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lol, here's a somewhat clear video on Youtube featuring the LM1875. (It only had 16 views when I clicked to see it.)

GC LM1875 - YouTube

If I wasn't lazy right now, I'd email that person to ask how the gainclone was built.
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Old 2nd September 2012, 07:15 PM   #28
johnr66 is offline johnr66  United States
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I run a pair of TDA2050s on a 25.2 volt 2 amp (~50va) transformer. I get 10 watts per channel at 8 ohms and 14 @ 4 ohm, both channels driven, before clipping. With one TDA, I get 18 watts into 4 ohms. Power sags with load, but it is doable.

With more voltage and current supply, I get 22 watts @ 4 ohms, 2 channels or 27 watts with single. I'd select stronger chip than push any harder than 25 watts IMO.
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Old 2nd September 2012, 07:19 PM   #29
AndrewT is offline AndrewT  Scotland
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Quote:
Originally Posted by donpetru View Post
.................. I tested the audio system and they were right because is 5.1 system. ....................
do-able and perform properly are quite different.
It doesn't actually have to break to be bad.
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Old 3rd September 2012, 02:06 PM   #30
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Can anybody post a circuit diagram using lm1875
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