ETI-480 100W Amp .. please help

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M Evil, i suggest you to forget this amplifier...really not so good!

The amplifier is something that you can call average (medíocre) having not special sound.

I tested it deeply, i changed all transistors for hi speed units, Miller capacitors reduced, used Silver Mica units.... bias adjusted, no off set, voltages correct, nothing wrong with it related construction.

.......................................................................................................

SC480 really have adequacy to its price...low price and also low quality
The amplifier sounded week in power, without good presence, showing some peak around 250 Hertz
Top high frequencies disappeared from my unit, well, amplifiers never the same, another can give better response.
Bass is out of control, seem a big drum with the acoustic leather loosen... too much short in timing and frequencies
seems to be the same all the time, alike one speaker with terrible ressonances related 250 Hertz...so, when driven
always will convert some frequencies to something different.
Details disappeared, and i tried using very special capacitors too, also reduced the Miller in a try and error basis,
output inductor changed to lower values but negative, work better with enormous 5,6 microhenries.... and 150N to
ground!...Oh! my God!
The input capacitor was changed many times, ceramic, bipolar electrolitics, poliester and Tântalum, beeing the last
one producing better results.
The amplifier is not so sensitive, but saturates easy, and the distortion, when over driven is something that came
from eleventh underground stage, there!...deep in the hell.... seem gases beeing liberated in the bass region.
I think it is a very poor amplifier.

The killer example:

Music theme of Brave Heart movie; There are moments than Pipes start to play.... and the sound produced, together
with other instruments produce wonderfull result...yes...some harshing effect, not a defect!...with this amplifier i have to
go all the way up in volume to perceive something...very mufled and poor in detail...this amplifier is not good in my point
of view.

In Australia you have amplifiers that can smashed and desintegrate this unit, flatting it to the correct high they reserve
to be.

Carlos, accidentally now acting alike a Destroyer, but "In the name of truth and decence!"

regards,

Carlos
 
The board image, good luck to you, Mateus made one unit that sounded nice

I made all i could, and could not have good sound.

Better luck to you.

regards,

Carlos
 

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My unit will receive a double barreled shot... 2 twelve gauge will kick it out!

But this do not seems that the amplifier is always bad.

As i told you, Mr. Mateus made one very good sounding unit, and he prove that making professional recordings and send me to check...really, his unit is wonderfull related the sound i could achieve in my home....maybe my speakers...well, those things are dependable of too many variables, judgment of quality is not always precise, and normally subjective.

Even comparison tests will depend from the speaker you choice as "Monitor unit!"

regards,

Carlos
 

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