This amplifier output stage is in TEF ???
if it is can i use without it but how??
Replacement for MJ15020 and MJ15021
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Output stage is a tripple darlington Emitter Follower (EF) arrangement.
Replacements for MJ15020-21 (tested with success) are MJL1302A - 3281A.
Hi Fotios ,
Made your Amplifier long back ago, tested it up to 100-0-100 v d.c. It rocked even on 1 ohm load. I used 10 pairs of 15024-25 in output and 15022-23 in driving. Now I want to give it a try with 2sc5200 and 2sa 1943. Please guide me how many pairs I should use to get same power as 24 25 and up to what limit d.c. will be safer with sc-sa.Any more changes you suggest.
regards
Vedmitra Sharma
Made your Amplifier long back ago, tested it up to 100-0-100 v d.c. It rocked even on 1 ohm load. I used 10 pairs of 15024-25 in output and 15022-23 in driving. Now I want to give it a try with 2sc5200 and 2sa 1943. Please guide me how many pairs I should use to get same power as 24 25 and up to what limit d.c. will be safer with sc-sa.Any more changes you suggest.
regards
Vedmitra Sharma
thank you for good amp .lm disign it like this and about 1 year its work so fine.its have,nt distortionso so fine
Dear Zakzak, Fotios,
Nice Amplifier, I'm just curious with this circuit. If you don't mind, in your measurement. How many voltage would be measured from Ground to base of 2SC5200/2SA1943 and Ground to base of MJ15024/Mj15025?
Regards...
Hi Vedmitra
Thank you so much for your confidence in my amplifier circuit. Wow! +/-100Vdc supply rails, that is amazing! You should get around 2 X 550Wrms/8Ω! Congratulations.
Looking at the datasheet of Toshiba, 2SC5200 - 2SA1943 transistors are rated:
Pcase = 150W
Vce = 230V 2SC5200 / 200V 2SA1943
Ic = 15A
You should keep in your mind that ONsemi (former Motorola) transistors MJ15024 - 25 are unbeatable in robustness. Toshiba are some delicate and from those i remember from CREST PA amplifiers: max +/-90Vdc (90 - 0 - 90 V) and 9 pairs in output.
Yes, you could do this in the cost of a small loss in high frequency response.
Dear Zakzak, Fotios,
Nice Amplifier, I'm just curious with this circuit. If you don't mind, in your measurement. How many voltage would be measured from Ground to base of 2SC5200/2SA1943 and Ground to base of MJ15024/Mj15025?
Regards...
Thank you AN214Q for your kind words. I haven't use 2SC5200/2SA1943, never. The only data i have is for the original circuit (pre-drivers MJE15032-33, main drivers MJ15020-21 or alternatively MJL3281A-1302A and output MJ15024-25). For the measurement that you ask:
With input shorted to GND and without load in output, the voltage between the base of output transistors and GND is:
+0.54Vdc at the base of each MJ15024 (NPN) and -0.54Vdc at the base of each MJ15025 (PNP).
Practicaly speaking, will be the same. 20Hz to 20000Hz +/-1dB.
Don't worry so much about this, here we have to do with a PA audio power amplifier.
Yes sir however we cannot hear beyond 20Khz
then we cannot find change in the clarity of sound right??
I cannot hear beyond 8KHz
But keep in mind that PA speakers are very revealing of any difference due to high sensitivity (101 to 103dBSPL/1W/1m). In a same way, because we know that a PA power amplifier is designed to drive PA speakers, mid-high frequency area is of less importance than low frequency. Big 15 - 18" PA woofers demand lot of power to move, while mid - high compression drivers loaded with horns demand less power.
The difference is that: MJ15024-25 have Ft = 4MHz while MJ15020-21 have Ft = 20MHz in the expense of Ic = 4A. While the new MJL3281A-1302A have both Ft = 30MHz and Ic = 15A.
Hi Yanni
Your test results:
Vrms = square root ( Prms X Load ) = sqare root ( 550 X 4 ) = 46.9Vrms.
Vpeak = Vrms X square root 2 = 46.9 X 1.414 = 66.32Vp.
Irms = Vrms / 4Ω = 46.9 / 4 = 11.72Arms
Ipeak = Irms X square root 2 = 11.72 X 1.414 = 16.57Ap
This Ip is shared among 5 output transistors, so Ip per transistor:
Ipeak = 16.57Ap / 5 = 3.314Ap per transistor.
MJ15024-25 SOA curve (Safe Operating Area) shows:
Ic = 4.5A max for Vce = 70V
Well, you are inside SOA curve by 120%. You could feel safe yet under continuous operation of amplifier for many hours in peak power. I think is not necessary to remind you that blowers are needed for such usage.
Καλο Πασχα και καλη Ανασταση!
Φωτης
In few months. I have to finish two audio projects for which i received payment in advance. That will take me at least 4 months. Next from this i will design new, more flexible PCBs and upgraded protection circuit for Dirty Harry.
Please be patient.
great sound
thanks from my heart core that you gave us a design who's sound response i was searching since 2 years ,though i am not so skilled ,but i tried to make this amp.
but a problem i am facing that it heats much in spite of force cooling.i have used 1943/5200 in output as well as in place of mje15021/20.
sir i will wait for your kind suggestion.
thanks from my heart core that you gave us a design who's sound response i was searching since 2 years ,though i am not so skilled ,but i tried to make this amp.
but a problem i am facing that it heats much in spite of force cooling.i have used 1943/5200 in output as well as in place of mje15021/20.
sir i will wait for your kind suggestion.
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