MJL3281A/MJL1302A vs MJL4281A/MJL4302A, which will be better? - diyAudio
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Old 7th March 2013, 10:59 AM   #1
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Default MJL3281A/MJL1302A vs MJL4281A/MJL4302A, which will be better?

I'm building my power amplifier. I'll use ON-Semi power output transistors. I'm using Sanken LAPT 2SC2922/2SA1216 in prototype versions, but i like ON-Semi's transistors.
In my country, the prices of MJL4281A/MJL4302A same MJL3281A/MJL1302A, about >6.5$ each.
In datasheets, MJL4xxx have more Hfe, higher Ft. But MJL3281A/MJL1302A have symmetrical characteristics in complementary pairs and matched Hfe (within 10%) from manufacturer.
Characteristics show MJL3281A/MJL1302A look very symmetry between NPN & PNP, more than MJL4281A/MJL4302A.

So, which are better? I'll use 6 pairs in output stage, matched gain complementary pairs are very important!

Please tells me what you think. Thank you!!!
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Old 7th March 2013, 11:04 AM   #2
AndrewT is offline AndrewT  Scotland
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Not matched gain. Match the Vbe of the paralleled devices.
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Old 7th March 2013, 11:33 AM   #3
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Default Using power equalizer resistors, the emitter resistors, then

they will share the power equaly...you do not need to match then unless you will use a single pair..then you should match NPN and PNP

NPN and PNP is the needed matching to be performed.

If you have mismatched PNP and NPN, the result will be more an effect than a deffect.... harmonics will change a lot and you may love the result...i could find designer that makes a lot of effort to mismatch because the second harmonic result compared to third harmonic.

Comparison of these transistors can be made considering several aspects... because of power my vote goes to MJL4281A.... it looks more powerful... and this is very obvious, because it is more modern and they do not release worse new models if you compare to previous models.

Sanken 2SC2922 seems to play more treble.... it looks to me, but i have not made A to B comparison...so...it is just "i think so"...and i think so is not science.

The one i trust the most is MJL4281A and it's complementary.

regards,

Carlos
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File Type: jpg MJL4281A SOA.jpg (223.7 KB, 326 views)
File Type: jpg MJL3281A.jpg (302.5 KB, 310 views)
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Last edited by destroyer X; 7th March 2013 at 11:52 AM.
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Old 7th March 2013, 11:41 AM   #4
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There are ThermalTrak compliments to the devices you mentioned. Incorporating the tempco diode on the body of the transistor. This can significantly reduce thermal distortion. NJL3281 and NJL1302 are one such pairing. On Semi has an application note, and Bob Cordell discusses them in his book.
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Old 8th March 2013, 01:43 AM   #5
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Thanks to replies!
So, i agree with Destroyer's comments. MJL4281A/MJL4302A are modern devices with parameters better old devices. The symmetrical characteristics between NPN and PNP what i want comparison, and the MJL3281A/MJL1302A seem to be better.

So, if i buy MJL3281A/MJL1302A i must be match Vbe. Gain not needed, because the manuafacturer did it. 10% is good number, we're not commercial manufacturers, can't buy a tons transistors to match.
MJL 4281A/MJL4302A they'll need match Vbe and Gain.

To Jackinnj: I think i don't need the Thermal Trak devices. I'll use simple Vbe mutiplier. This's enough with me.
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