Dx Blame ES .... based into the Blameless, i am trying a new amplifier

[destroyer X]

Having fun, of course!

regards,

Carlos

[destroyer X]

schematic, as also, the comparison with the Dx amplifier standard.

The wire you may see around the board (third image), is my grounding system for fast scratched boards... they go around alike frame, colecting leads needing to be grounded.... horizontal up position runs the positive rail, down the board, also horizontal position, runs the negative rail.a... in the first image you see up the ground line (frame ground) and bellow you see the positive rail..watch extreme left, there's a capacitor drawn from positive to ground.

regards,

Carlos

[Rafael L]

I liked the name that you gave to the amplifier! Dx Blame ES

[destroyer X]

I have tested, and the amplifier really sounded better than my beloved Dx amplifier into the treble range....BUT.... have lost into the bass...the bass is weak, a shame!

Compared to Krill it sounded almost the same, and Krill is a very special amplifier, also was so good a beated by a very small amount the Techno by Bora..... my Dx HRII is almost the same into the treble range and has much more punch into the bass.

Nice unit, modified from Blameless..... will tweak for better bass.


Here is a link for a fast test made:

http://www.youtube.com/watch?v=llnRoZ_jno4


regards,

Carlos

[Rafael L]

But you already made the changes?

have lost into the bass...the bass is weak, a shame!

Is strange! Blamelles was to be good due to the high damping factor, bass should be similar to Symasym

[destroyer X]

But even this way the sonics have not changed enougth... the bass is stucked (entupido) seems stays inside the speaker and do not propagate into the air, vibrations are smaller, windows does not shake alike Symassym.

Seems to me it is very good into the treble range, maybe because when we loose bass in level and quality we start to perceive the treble...you know....this fools us a lot and i have to install the Osciloscope to observe what is going on into the waveshapes and levels with the amplifier loaded.

There's a very strange effect resulted of human global perception...we do not listen treble or bass alone, you can reduce treble really reducing high frequency level OR increasing bass...into the global perception you perceive this way...of course you can reduce bass increasing treble too... things are ballanced.

At this moment i am burning transistors, i have burned many drivers as i have not high voltage drivers, and the amplifier puts lots of power into the high frequency range (not oscilating for sure, real audio, nice quality, crispy highs)

Will fix that using power transistors (medium power devices To220) into the driver position as BD139 and BD140 are burning because supply voltage to high for them (42 plus and 42 minus).

A matter of fact is the amplifier really distort less into the high frequencies, but, despite the enormous condenser into the input (10uf) it is reproducing a weak bass...maybe because the input impedance is too low (15K)

Wonderfull to treble, an excelent amplifier to treble, i have tried the blameless original circuit first, them i have tweaked, including parts missed, the feedback capacitor for instance, rail voltage regulator also, a different current calibration into the differential, also i have produced a better VBE to the second VAS stage compared to the first stage.

Symassym is a great amplifier, but this one have eated into the treble...symassym when face high levels of treble, high frequencies, it harshes, this one NOT, this one intermodulates... strange effect, alike when you try to listen 20 kilohertz and another tone, from lower frequency is reproduced as a result (when you increase volume and force the amplifier to put out 20 volts (sinus) into 8 ohms speaker (real speaker system)... the Dx amplifier suffer from self erasure, alike overbiased tape recorders into the high end of the spectrum.

The amplifier is more to the Krill (excelent unit) and also Techno from Bora (another lovely one)....may even beat Krill into the treble, but into the bass low end it is stucked (entupido)

O grave é uma verdadeira lerda!.... the bass is real a ship!

I am having a lot of fun, a pitty that i have not higher voltage complementary units to the driver position, some transistors went dead because i have insisted to replace them keeping the volume lower...but i could not resist to increase....and them they popped with flames....very nice to see, and sad to loose nice parts..... the NPN driver is going, maybe the hell CCS is doing that, sending huge current to the VAS, the transistors are operating around 590 milivolts, and this usually is too much, usually i have from 520 to 575 milivolts from base to emitter....will reduce current.

regards,

Carlos

[destroyer X]

burning, it goes in flames, yellow flames, when other pops a blue ligth and the transistor case is opened with a clear hole or a slice is busted!

Also the unit burns the stop resistors...i do not know if those resistances are too much weak (new ones i have received from Greece) but they carbonize easy and smells a lot.

The amplifier seems not to have a good mood when i ask high levels nearby the clipping levels.

At this moment it is into the repair table, i am waiting the sunrise to fix.... home ligth is not very good for that, also my head produces shadows.... waiting for the sun.

regards,

Carlos

[destroyer X]

and less than 20 volts RMS from colector to emitter..this is something around 700 miliwatts, no reason to burn this way.

Maybe the unit is having oscilations into Very High Frequencies driven by the signal, you know, bursts of oscilations when you have high frequencies into the the audio envelope....maybe this is happening.

Will watch into the scope.

regards,

Carlos

[destroyer X]

The amplifier was fixed and now the bass is strong, the amplifier has a bootstrapp (ahahahahah!) to feed the dual transistor VAS (Self) and some other modifications.

Sounding lovely...but...loves to oscilate that input..... when you power off you listen the noises that are signs of oscilations,

But the amplifier, while powered is now stable...and you can put your finger tip into the input and only 60 hz mains hum will be listened.

Lovely Dx Blame ES..... uncle Charlie gift to forum friends, in special the Dx Corporation people that has assembled Dx amplifiers.

I am evaluating..it is not HRII, nor Precision1, it is in another class.

THD is 0.00222% into 1 kilohertz and full power
THD is 0.01254% into 10 kilohertz and full power

regards,

Carlos

[wahab]

Originally Posted by destroyer X

Will fix that using power transistors (medium power devices To220) into the driver position as BD139 and BD140 are burning because supply voltage to high for them (42 plus and 42 minus).

A matter of fact is the amplifier really distort less into the high frequencies, but, despite the enormous condenser into the input (10uf) it is reproducing a weak bass...maybe because the input impedance is too low (15K)




Carlos

BD139/140 are not the good devices to drive powers bjts at this level..
the datasheet show collapsing beta at more than 100 mA...
since bass are current demanding, no wonder that the bass is weak...
try BD791/792...if you havent some, use whatever you have that is
not as current restricted as your current drivers..


regards,

wahab