Mjl21194 & Mj15003

gregjpeters · 12th March 2008, 01:44 AM

Hello all,

A quick question.

Would the MJL21194 or MJ15003 be a more linear device at class-a bias currents over 1.5 amps? I note that the datasheet for the MJL21194 shows the linearity dropping off over 1.5A at higher temperatures, however I have been unable to find a sufficiently detailed datasheet for the MJ15003.

Is there any other reason why one is better than the other in your opinion? One advantage of the MJ15003 is a higher SOA and power dissipation, but the flatpack packaging of the MJL21194 is also a big positive in my opinion.

I currently run MJL21194s in my JLH at 1amp bias and they sound great, but I want to wind the bias up to 1.5-2 amps while still only using single output transistors. Maybe the MJ15003 would be better for this?

Thanks,

Greg.

sandyK · 12th March 2008, 06:43 AM

gregjpeters
I seem to remember reading that the 21193/21194 were one of
the first of the enhanced beta types and performed better into 4 ohm loads than previous types. To quote from a Silicon Chip
Class A project in 1998 : "We used them because they are achknowled to be among the very best transistors for linearity
made by any manufacturer in the world. And by using them at much lower current than their design currents and voltages
we get even better linearity."
The 1302/3281 etc are even better again.

SandyK

GK · 12th March 2008, 07:26 AM

Quote:

Originally posted by gregjpeters
Hello all,

A quick question.

Would the MJL21194 or MJ15003 be a more linear device at class-a bias currents over 1.5 amps? I note that the datasheet for the MJL21194 shows the linearity dropping off over 1.5A at higher temperatures, however I have been unable to find a sufficiently detailed datasheet for the MJ15003.

Is there any other reason why one is better than the other in your opinion? One advantage of the MJ15003 is a higher SOA and power dissipation, but the flatpack packaging of the MJL21194 is also a big positive in my opinion.

I currently run MJL21194s in my JLH at 1amp bias and they sound great, but I want to wind the bias up to 1.5-2 amps while still only using single output transistors. Maybe the MJ15003 would be better for this?

Thanks,

Greg.

I doubt that the MJ15003's hfe linearity would be better than that of the MJL21194. Also (according to the ON semi datasheet), the MJ15003 has a nominal fT of 2MHz, half that of the MJL21194 and a much bigger collector-base (Cob) capacitance of 1000pF.
I'd go for the MJL21194.
Also, in case you might consider using a 30MHz fT part such as the 1302, just be wary that if your JLH amp is dependant on the limited bandwidth of the output stage for stability, or is not sufficiently well layed out, such parts could make it an oscillator.

EUVL · 12th March 2008, 04:34 PM

MJ21194 has much better linearity (constant hfe) from 0.5 to 3A than MJ15003, according to my own measurement (at 1kHz).

Patrick

EWorkshop1708 · 12th March 2008, 08:09 PM

MJL4281 and 4302 are Flat Pack devices, and have a very good linear gain curve.

They even have a ThermalTrak version of the NJL4281/4302 with a temp diode inside. I imagine the direct temp tracking would be a benefit in a Class A amplifier.

gregjpeters · 13th March 2008, 01:12 AM

Thank you all for your replies. The MJL21194 it is!

Unfortunately some the faster alternatives some of you have mentioned are not suitable for this amplifier which relies on low speed transistors for stability.

Cheers,

Greg.

sejati · 13th December 2008, 04:42 PM

Greg, you have use MJL21194 for the JLH class A design did you ? Do you experience oscillation as well ? or humming ?
How's the sound ? did you manage to bias for 2 Amp or more ? And hows the result.

Well I try using recommended MJ15003 double and bias 2Amp.
The bass is as detail as the mid and high. But I intrigue about MJL21194, as it is reported better linearity.

Maybe Greg could give us some clue here...

12th March 2008, 01:44 AM	#1
gregjpeters diyAudio Member Join Date: Nov 2002 Location: Brisbane, Australia	Mjl21194 & Mj15003 Hello all, A quick question. Would the MJL21194 or MJ15003 be a more linear device at class-a bias currents over 1.5 amps? I note that the datasheet for the MJL21194 shows the linearity dropping off over 1.5A at higher temperatures, however I have been unable to find a sufficiently detailed datasheet for the MJ15003. Is there any other reason why one is better than the other in your opinion? One advantage of the MJ15003 is a higher SOA and power dissipation, but the flatpack packaging of the MJL21194 is also a big positive in my opinion. I currently run MJL21194s in my JLH at 1amp bias and they sound great, but I want to wind the bias up to 1.5-2 amps while still only using single output transistors. Maybe the MJ15003 would be better for this? Thanks, Greg.

12th March 2008, 06:43 AM	#2
sandyK diyAudio Member Join Date: Apr 2007 Location: Sydney	Mjl21194 & Mj15003 gregjpeters I seem to remember reading that the 21193/21194 were one of the first of the enhanced beta types and performed better into 4 ohm loads than previous types. To quote from a Silicon Chip Class A project in 1998 : "We used them because they are achknowled to be among the very best transistors for linearity made by any manufacturer in the world. And by using them at much lower current than their design currents and voltages we get even better linearity." The 1302/3281 etc are even better again. SandyK

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12th March 2008, 04:34 PM	#4
EUVL diyAudio Member Join Date: Oct 2003	MJ21194 has much better linearity (constant hfe) from 0.5 to 3A than MJ15003, according to my own measurement (at 1kHz). Patrick

12th March 2008, 08:09 PM	#5
EWorkshop1708 diyAudio Member Join Date: Nov 2004 Location: Florida	MJL4281 and 4302 are Flat Pack devices, and have a very good linear gain curve. They even have a ThermalTrak version of the NJL4281/4302 with a temp diode inside. I imagine the direct temp tracking would be a benefit in a Class A amplifier.

13th March 2008, 01:12 AM	#6
gregjpeters diyAudio Member Join Date: Nov 2002 Location: Brisbane, Australia	Thank you all for your replies. The MJL21194 it is! Unfortunately some the faster alternatives some of you have mentioned are not suitable for this amplifier which relies on low speed transistors for stability. Cheers, Greg.

13th December 2008, 04:42 PM	#7
sejati diyAudio Member Join Date: Dec 2008	Greg, you have use MJL21194 for the JLH class A design did you ? Do you experience oscillation as well ? or humming ? How's the sound ? did you manage to bias for 2 Amp or more ? And hows the result. Well I try using recommended MJ15003 double and bias 2Amp. The bass is as detail as the mid and high. But I intrigue about MJL21194, as it is reported better linearity. Maybe Greg could give us some clue here...

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