Dx Blame MKIII-Hx - Builder's thread

[vargasmongo3435]

I made a mistake on post #1472 missing trace on the board sorry about that next time will check more times.

Regards
Juan

[canonnica]

... back in the listening environment...
the high-bias setting of 54mV let the amp sound dull and kind of tarnished. Less engaging, less crisp. As expected and mentionned everywhere on this forum, adjusting the bias is like putting salt on a soup. Some will like it with more, some with less. I've made some listening tests at 16mV and 24mV. For now, it's set at 16mV and I'm quite satisfied by the balance.

The 100 Ohms base-stopping has permitted going upper than, let's say 12mV (it was oscillating) so to try and listen to it. My mods are there to stay. 16mV also has the advantage not to transform the amp into a room heater.

Juan, about your boards. Personnally, I would work in the opposite direction you actually do. The boards were already quite big. Making them bigger will make builder's life even more complicated. And I'm not sure you solve any real world issue we faced; not enough space for some electrolytics, holes too small for many components (ex: diodes), cooling for VAS and its CCS, a missing capacitor on the schematic, etc...

Why don't you try to create a board with no reservoir caps and only 3 output pairs and plan to only use 54-56VDC input and rate it at 150W into 8 ohms? This would be more than enough for the majority and ease it's adoption. (these are my 2¢ only, you'Re the boss )

Martin.

[a.wayne]

So best for you is base stoppers at 56 ohm and bias at 16mv ..?

[destroyer X]

Much more sweat, sensitivity than wisdom.

Some folks believe calculation is the solution...no way.

I am glad you are concluding this stuff doing...i feel good, as i am 8 years long repeating the stuff and some guys thinking i am crazy.

In a matter of monthes we gonna have hundreds thinking the same way...because it is a real knowledge..tunning, calibrating, adjusting.

You will see that some errors contribute to some result.... make some big mistake..for instance..install positive rail a big resistor...much bigger than the negative and watch the harmonics.... wanna tube alike sound..then mess with the amplifier, because tube performance (at simulators and instruments) are awfull.

regards,

Carlos

[destroyer X]

with three output pairs..this will drive the boss to become mad because the Corporation phylosophy not to make two amplifier almost the same...unless too much needed.

Doing this way he will go to the past.... an advance to the past.... a step ahead backward?

Please, spend a couple of minutes and watch this project here....the Supercharged is almost the same if Juan produces the smaller board you have suggested:

DX Blame Amplifiers - Carlos Mergulhão

I do think uncle charlie will dress the "boss clothing " and will start to bite Juan in the rear back bumper.

ahahahahah!

regards,

Carlos

[vargasmongo3435]

Yeah I almost made a mistake to redone something that was already good enough I rather leave it like that is ok connonica and Carlos it think is better leave it that the board was made from meanman64 group buy many people have it including myself and satisfied with the sound I'm not an expert but I'm just happy that I build it also MKII Supercharged is more than enough maybe later but is just not necessary.

Regards
Juan

[canonnica]

Originally Posted by a.wayne

So best for you is base stoppers at 56 ohm and bias at 16mv ..?

I went with 100 Ohms. Tweak you own and make it sound like you want it to sound to...

[destroyer X]

This needs a pcboard.

I am also preparing a SMPS together Zimmer.

regards,

Carlos

[canonnica]

I found a used 'scope and started measuring things.

I used an iPhone app as a signal generator, surprizingly it's quite good.

I used a resistive load of 6 Ohms for all the tests.

Here's some traces... we can observe some negative rail sticking when pushed beyond clipping, but up to there, it's just sweet.

ENJOY!!

This is for channel A

[canonnica]

And channel B...