2n3055

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I would use the 2N3055 & MJ2955 to test the circuit DC bias, cross-over and such. Then replace them with better devices. If you have made a mistake in your circuit and power it on, and the outputs go "POOOOOOFFFFFFFF":hot: then you haven't lost all that much $$$$. It is when you blow out really good expensive devices that make you cry.:bawling:
 
Rigth Lizandro, lets go into the rails again.

I had informs, 20 years ago, that people were using 2N3055 as amplifier loads....do not remember, but the obvious connection is a resistance divider from from colector to emitter, with the center tap connected to the base, to force it into conduction.

I think had two types, one of them was with some battery, and another, less precise, worked without batteries.

Very interesting, as can be some 100 watts load (using heatsinks) and can be adjustable.

Some capacitance, some inductance will go together the resistance, but this is unavoidable.

If someone knows how to calculate, to have some step switch to adjust the load....it may be good for a lot of guys in this forum.

For me, of course, will be great!

regards,

Carlos
 
Despite the people's headbache, those exact same transistors in output are very nice.

See that one, perfect for you i imagine.

Wave forms are wonderfull, Wave form Monitors will be very happy, related the sound, can be great too, have to ask someone that assemble and have others to compare and say something to you referenced in some amplifiers.

Because Great, and Good, are "empty" words, if not Better than, equal them, worst than.

Not referenced with others, i can be a magnificent runner, with my 300 pounds weigth, i can go really fast...... compared to some athletic guys, i am alike a turtle.

regards,

Carlos
 
I built a small 50W amp using TO3 2N3055 and MJ2955 to drive a 4 ohm speaker, and it's amazing how clear this amp plays.

I got the heatsink out of an old powersupply back in High School 6 yrs ago and it had 2 2N3055's in it. I was going to go quasi-complementary and use both, but instead I went Sziklai because I was able to get a matching PNP MJ2955 for only $1.80, so I kept my other 2N as a spare.

What I like about TO3 transistors, is that they take a lot of power before they heat up, and they seem tougher IMO.

Now of course, the amp I built with these transistors is low power, but I'm considering going TO3 again when I build another amplifier but use newer ones like MJ15003, etc.

If you put your finger on flat pack transistors with the volume cranked, while the heatsink is still cold, you can feel them get warmer than the heatsink at first, but TO3 don't seem to do this as much.
 
This test you make, is the same we make with Radio frequency transistors

O dedômetro, or the fingermeter is used and is precise.

As our body temperature is around 36 centigrades, the transistor capsule must be perceived as a fever..... and when the capsule is hot alike a fever, or higher as microprocessors (55 centigrades), this seem the heat transfer is not adequated.

When you put finger over and heat is alike the heatsink , there's a problem...no good heat transference to air.....if you feel that the transistor capsule is hotter than the heatsink...no doubts it will burn!

Because when we measure the capsule, as 40 degrees centigrades...the junction can be near the melt temperature...so, capsule must work warm, or even with some temperature hard to perceive..

There are many bad constructions...i love Sanken devices...but the heat transfer is deeply stupid...the real transistor, the chip, is fixed in a small metal plate that is electrically soldered to a bigger plate that will be the real thermal conductance plate.... this method is awfull to heat transference.

Despite of that, those transistors are very powerfull...but could be better...maybe 20 percent better if better constructed.

In Radio Frequency, the transistor top are made of ceramic.... we switch of and we touch the ceramic...if hot..... untuned transistor...it will represents that the one will burn..... so, we tune the unit again.... having bigger voltage output, and reducing a little the current...the product remains the same or go up..voltage multiplied by current, as you know, means power.

The finger meter is hardly used...and is the only one that guarantee the transistor life...as that measure never fails...ceramic hot.... situation bad....mis tuned, small heat sink, error in the load impedance, or excess of driving signal.

I will make a scratch about the SANKEN 2SC2922 construction...those units i removed from a Pionner Amplifier, so, i suppose they are not fake.

regards,

Carlos
 
The scratch i told ya.

Carlos
 

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The 2N3055/2955 are very capable power transistors for audio. Of course, there're better choices (more linear, less noisy, with better power handling), but that doesn't mean an amp built with such transistors will sound like crap.

My JLH '96 currently uses 2N3055 and sounds like a dream.

I agree. It is possible to create a very large power amplifier of excellent quality using these devices. If they are that cheap and you have the urge, you can parallel them and cascode the paralleled banks of transistors to handle a large voltage swing and still get excellent quality from these old epitaxial transistors. That being said, with modern devices the same results can be had using much less components. You can build a sophisticated calculator using tubes and it would work, but what is the benifit when the same thing can be done with a small low power IC?:rolleyes: If you can aquire them for such a cheap price and want to show that it can be done it is quite possible but maybe not so practical.:xeye:
 
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