Dx Blame ST together Dx Super A

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AndrewT

R.I.P.
Joined 2004
Are you joking?

500mA of output bias allows a maximum of 1Apk for ClassA output current.
a +-25Vdc PSU probably allows a ClassAB output of around 20W to 25W
That 1Apk equates to <4W of ClassA
That means your amplifier is NOT a ClassA type.
It is a high bias ClassAB with added crossover distortion, due to non optimal ClassAB biasing.
 
T

thimios

Member
Joined 2009
AndrewT said:
Are you joking?

500mA of output bias allows a maximum of 1Apk for ClassA output current.
a +-25Vdc PSU probably allows a ClassAB output of around 20W to 25W
That 1Apk equates to <4W of ClassA
That means your amplifier is NOT a ClassA type.
It is a high bias ClassAB with added crossover distortion, due to non optimal ClassAB biasing.
Click to expand...
This amplifier has change values ,resistors,capacitors,power supply, so many times.......:confused:
 
J

junior35

Member
Joined 2008
thimios said:
This amplifier has change values ,resistors,capacitors,power supply, so many times.......:confused:
Click to expand...

Yes Thimios,this is true DIY. Would you rather be spoon fed back to the Eico,Heathkit and Dynaco age? Even in that era there were modifications to the kits after production. Screw ups happen in DIY. That's the beauty. Enjoy life.....bring the Ouzo and let's break some plates!

Cheers
 
destroyer X

destroyer X

R.I.P.
Joined 2004
youtube.com/channel/UC9xnp-350vDnDhEpNv_XVxg
I have asked Eduardo Silveira a new recording because the one published

in the previous post was showing saturation in the recording or some problem in the mid range driver or tweeter...it is harshing...not perfect..and this amplifier does not sound this way.

regards,

Carlos
 

Attachments

  • Eduardo Silveira foto ST.jpg
    Eduardo Silveira foto ST.jpg
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destroyer X

destroyer X

R.I.P.
Joined 2004
youtube.com/channel/UC9xnp-350vDnDhEpNv_XVxg
Dear Cook77 and Vrystaat, the one build was not me, was Mr. Silveira

from Brazil..... he asked me to remove because he made bad recording and this will harm the brand as audio quality is not fine.

I will ask moderators to remove these videos and Mr. Silveira will make new ones soon....of course i gonna publish them here.

Was not me the builder..i am showing something a friend did with my amplifier circuit but i gonna search for the circuit he used to the meters...i suppose was some germanium diodes or silicon diodes as rectifiers.... some nanofarads as filters and a resistor...not more than that...but i will ask the guy the schematic to post here...the meter driver schematic.

Thank you all by the understanding..will ask moderator to remove these videos...was the video owner that asked me as he perceive it is a shame the audio quality in the recording..he gonna try to make it better..less level, more absortion material around...better light, flat recording without tone controls...well...he will manage to make better audio recording.

regards,

Carlos
 
destroyer X

destroyer X

R.I.P.
Joined 2004
youtube.com/channel/UC9xnp-350vDnDhEpNv_XVxg
Sorry Bagus, not installing new stuff in my PC.... afraid of viruses

A friend asked me the VU Meter schematic.... so, dear Cook77 and Vrystaat.

Here you have it.

Capacitor in parallel with the meter will make it move more "average" like..gonna slow down the movement....may hold for a while.

regards,

Carlos
 

Attachments

  • VU Meter schematic.jpg
    VU Meter schematic.jpg
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destroyer X

destroyer X

R.I.P.
Joined 2004
youtube.com/channel/UC9xnp-350vDnDhEpNv_XVxg
Here you have a video about Eduardo Silveira...i have asked him to make a new video

Because the first one had bad audio recording...harshing sound.

But i am afraid you will not listen the audio..... he used a song that may be blocked...he know nothing about Youtube regulation and international laws.

This amplifier you see, the enclosure and pre amplifier is a Brazilian Quasar made from 1980 to 1988...inside there are Dx Super A modules and also a Dx Supply.... original Quasar pré amplifier is beeing used.... TL071 based circuits...tone control and filters.

regards,

Carlos


https://www.youtube.com/watch?v=cS-Hth9X5DE
 
Last edited:
C

cjkpkg

Member
Joined 2008
I just did the 180 ohm swap for R4... I will say this was a solid amp to begin with and I am not sure how to describe the effect I would say less tiring, more transparent...maybe vocals are a little more transparent.

I am running this in a TO-3 version with MJ15015/6 at pretty high idle current. Still one of my favorite amps.
 
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