Dx Blame ST together Dx Super A

[destroyer X]

that i forgot a very important feature into the pcboard.(%#@%*).... sadly my 62 years old are showing effect...i forgot the protection fuse to the ouput speakers.

Your expensive speaker reminded me that..... and people asking for other transistors also made me thing about.

Using other transistors, the possibility to have a damage increase a lot.... people mistake about the type of speaker they will be using (not your case..yours is safe) can become a tragedy....if the output transistors, a more weak version from the sugested ones, be fried in operation...then a supply polarity will appear in the output....if the NPN fry, then +42 volts will cross the speaker coil and will destroy it....if the PNP fry, then -42 volts will cross the speaker coil and will destroy it... so...the use of other transistors, added to the missed output fuse, is a very dangerous combination.... having the cooperation of a young crazy guy that goes paralleling speakers...then ...boooom!

Reason why i am suggesting, now!, people to install, outside the pcboard, fuses in series with the speakers.... use 3.5A fuse (slow blow) to 8 ohms speaker, and 7A fuse or 8A fuse (slow blow) to 4 ohms and 15A fuse to 2 ohms speakers.

Power amplifier fuses are half of that... 1.75 or 2A fuses to 8 ohms..... 3.5A fuses to 4 ohms operation and 8A fuses for 2 ohms operation...there are two fuses in the power amplifier pcboard, one for the positive rail and other for the negative rail.

Yes...the rail fuses may melt and protect...but just in case..put a speaker fuse too.

Do not be scared.... using the suggested huge transistors nothing will happens...i have saturated the amplifier for long time..when it was very hot, i have disconnected the fan blower..i have use 2 ohms together 2uf in the output and nothing happened...but if people try weaker transistors together 2 ohms....then....something bad can happen.

[destroyer X]

Amplificadores DX Blame - Carlos Mergulhão

Mitchel made this one based in Silicon Chip Magazine...i do not know how similar or different it is compared with the Silicon Chip Magazine text.... in my imagination he may have used the idea and not the circuit itself.

It can be used with the Dx Super A.

pcboard must be made by yourself, etch at home..we have no more boards available.

regards,

Carlos

[Project16]

I will anyway put a protection !

I saw on the brazilian forum mentioned the "Blame DX" changed to class A polarization.
But with only two bjt output output power is reduced?

[destroyer X]

100 guys have assembled in Brazil having these green boards...more 100 guys have assembled using the Supercharged blue boards*, so, they already have their green pcboards to be adapted...they will use fan blower and will not install 2 ohms speaker anyway.

This was an effort to allow them to use the old pcboards they still have without the need to make another one or to have the need to order new pcboards...they can operate Class AB high biased to 90 miliamperes or even use 250 miliamperes without having the DC bias reduction we have in the Dx Super A.... other options to them to continue with their pcboards.

There are several options... Super A, High bias Dx Blame ST operating class AB and normal bias Dx Blame ST operating class AB (30 mA) but using the new tune Dx Super A circuit values.

It is "a la carte" service.... customized to my friend's needs.

This amplifier is an old story that started with the Dx amplifier and evoluted passing to be several new models with different power and features, but keeping the main frame..the skeleton came from the Blameless amplifier from Doctor Self...tweaked an evoluted till the bones...a sequence in the diy brandname evolution...it has a history and more than 200 kits were provide to Brazilians.... this is an effort not to allow them to loose their pcboards already assembled..they can just substitute some parts to have the upgrade and updated, last model, ultimate model, the Dx Super A...that came and started from the Dx Blame ST...and the Dx Blame ST came from other previous models too...a sequence of models..having something alike, the brand identity.

An old story, and history, posted in several threads and several amplifiers...a very long run that i cannot explain you as gonna be a book in size..threads are there for you to watch...type Destroyer x and Dx and you gonna have more than hundred threads.... all this stuff started in 2004 (in this forum)... actually, my search for audio amplifier performance and studies started in 1960.
Dx Super A is a grand, grand, grand, grand, grand, grand, grand, grand son of the Dx amplifier (2004)

Sequence is more or less this one.

Dx Amplifier
HR II
Precision 1
Dx Trust
DHR Turbo
Troyan
Dx Blame ES
Dx Blame ST
Dx Supercharged
Dx Blame MKIII Hx
Dx Blame MKIII - Home Edition
Mako
Dx Super A

New amplifier to come to release July 2014 at my own forum first...in December in diyaudio too... Mako II

* http://www.nabucoeletronica.com.br/dx/home.html

regards,

Carlos

[Project16]

It's decided, I'll make a Blade DX Super A (for great sound)! The video on youtube fascinate me. The only thing that is annoying is the size of my Sanken.
I'll keep you informed of the progress of this project.

A big thank you!

[destroyer X]

Votre décision est parfait... your decision is perfect...i ensure you that you will never regret about that.... never!

Today, me and Juan, we gonna torture the amplifier:

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

regards,

Carlos

[Project16]

Hello destroyer X!

I have the solution to fit my transistors (Sanken) a printed circuit board against but I have a doubt about their position on the heatsink.
In fact they are positioned either on the bottom or on the top of the heatsink.
Ideally in the center but it is hard to do.
There will be a problem of heat dissipation and if they are positioned?

Thank you again!

[destroyer X]

But we will need an "L" shape adaptor that you can see watching this video, it is an "L" shape profile.

Dx Supercharged Blue pcboards available - YouTube

regards,

Carlos

[Soheil95]

What is the suitable transformator for DX BLAME ST SUPER A?

[destroyer X]

It can put out more or less 70 watts at low distortion... can go more, with reasonable distortion, can reach 90 watts RMS at 8 ohms.... in this case you have the need of 150 to 180 watts (VA) transformer to 1 channel.... to each channel .... if you decide to use a single transformer and a single supply to feed two channels, then you must have a 300 to 360 watts (VA) power transformer..depending if you adjust your volume lower than the threshold of distortion or higher than the threshold of distortion....this depends on the music you play and the volume you like to play and how sensitive are your ears to clipping and harmonic distortion....

Transformers are 30 plus 30 volts AC, because after rectification and filtering you gonna have a resultant DC voltage of 42 plus 42 volts.

So, first answer goes to 8 ohms.....transformer should be 150 watts(VA) each if you intend to buy two transformers........or 300 watts (VA) to feed two channels using a single transformer.

So, second answer goes to 4 ohms speakers.... transfomer should be twice the above current.... 300 watts each one of two transformers if you intend to buy two transformers and to make two separated supplies, each one of them to feed one channel...or 600 watts (VA) single transformer if you intend to use a single power supply.

So, third answer goes to 2 ohms speakers.... transformer should be twice the above current, or 600 Watts (VA) each one of two transformers if you intend to buy two transformers and to make two separated supplies (transformer, plus rectifiers plus filters).... but if you decide to use a single power transformer to feed two channels..then the choice will be 1200 watts power transformer.

This amplifier can put out aproximatelly 70 watts at 8 ohms each channel, 150 watts at 4 ohms to each channel and can reach 320 watts rms to each channel at 2 ohms loads.

Fuses to the positive and negative rails should be:

8 ohms speakers = 1.5A plus 1.5A...these goes into the audio amplifier pcboard...output series fuse can be 3 to 3.5 amperes..slow blow fuses.

4 ohms speakers = 3A plus 3A ... these ones goes into the audio amplifier pcboard .... output series fuse to the speaker can be 6 amperes.

2 ohms speakers = 6A plus 6A ... these ones goes into the audio amplifier pcboard.. output series fuse to the speaker can be 12 amperes.

Electrolitic condensers for filtering you calculate... use 5000uf to each ampere...so....if your supply will power a single pcboard at 8 ohms...then it is 1.5 plus 1.5 amperes..then put 7500uf plus 7500uf or more as filters...rectifiers should be twice this power.

You see that for 2 ohms you gonna need 30 thousand microfarads to each rail...so... 30K plus 30K...and this to a single power amplifier..reason why i suggest you to use a series pass regulator that has capacitance multiplier effect or search for something alike Dx Power Supply..... you can find it at the Power Supply forum.... for sure others may fit, the electronic filtering reduces the ammount of capacitance from several electrolitics....this is too much expensive when you drain high current.

Primary fuses you divide the power of your transformer expressed in watts by your mains voltage...then you have the fuse, use the value or the immediate superior value found in the market.

Heatsinks:

To each 10 watts of audio power ( the maximum power you gonna reach depends your transformer power and depends on your speaker impedance) then use an aluminum blade of 10 by 10 centimeters (4 inches by 4 inches..so..squared)...this is the equivalent size to 10 watts of AUDIO power... so.... depending your power you can evaluate your heatsink...use fan blower anyway... this heatsink dimension (tested in laboratory, under 30 degrées centigrades environment being able to face a 10 watts RMS audio amplifier, operating class AB or class B, having sinusoidal signal in the output, undistorted or unclipped waveform)

This is to continuous.... music is average.... this results twice the needed size for music...so...you can calculate.

But Class A and Super A operation is different..generates too much heat and these calculation does not make any sense.... reason why i suggest to install fan blower having LM7808 or even LM7805 or other manufacturer, voltage regulator integrated circuits to power the fan, reducing voltage will reduce fan speed and fan noise....but be attention, these Voltage Regulator Chips have a limit of input voltage you should see in the datasheet.

regards,

Carlos