Andreas W
The horses are still in the stable , I was heldup elswhere and could not give time to this project ,
Will it be ok if I increase the number of output devices to ten pairs and forget about two ohms , an output of 800w at four ohms is enough for my use .
These Toshiba devices are being used by most manufacturers they should be good .
Rajeev
The horses are still in the stable , I was heldup elswhere and could not give time to this project ,
Will it be ok if I increase the number of output devices to ten pairs and forget about two ohms , an output of 800w at four ohms is enough for my use .
These Toshiba devices are being used by most manufacturers they should be good .
Rajeev
10 pairs are OK, but see to that you are using sufficient drivers. Don't count on that you have full beta Hfe under severe load conditions. MJE1503X are I think reliable and can take the load.
I friend of mine services big PA amps, when motorola started making MJL1302/3281 and the alike transistors the manufacturer swapped their japanese transistors for motorola. He nearly got out of job, very seldon any amps blew up anymore. There IS a major difference in quality.
Andreas. (Not yet paid by ON semi)
I friend of mine services big PA amps, when motorola started making MJL1302/3281 and the alike transistors the manufacturer swapped their japanese transistors for motorola. He nearly got out of job, very seldon any amps blew up anymore. There IS a major difference in quality.
Andreas. (Not yet paid by ON semi)
Hi Andreas ,
Thanks for the advise ,
now as I have reduced the power rating of the amp I can use MJE1503X drivers , eirlear I had planned to use 2SA1943/2SC5200 pairs in output and the same in the driver stage . I have never seen any negetive complaints regarding the above devices regarding quality , however I have selected them as they are more easily avilible than the motorolla here .
I wonder how the branded poweramp manufacturers getaway with very limited devices in the output , for example QSE MX3000 has 6 pairs of output devices in each channel & RMX2450 has 4 pairs per ch .
with regards
Rajeev
Thanks for the advise ,
now as I have reduced the power rating of the amp I can use MJE1503X drivers , eirlear I had planned to use 2SA1943/2SC5200 pairs in output and the same in the driver stage . I have never seen any negetive complaints regarding the above devices regarding quality , however I have selected them as they are more easily avilible than the motorolla here .
I wonder how the branded poweramp manufacturers getaway with very limited devices in the output , for example QSE MX3000 has 6 pairs of output devices in each channel & RMX2450 has 4 pairs per ch .
with regards
Rajeev
rajeev luthra said:
Mark Levinson used 3 parallel connected MJE1503x as the driver for 8pairs of MJ15024/25 in No 23.5
sajti
#1 Commercial poweramps blow up.
#2 Most speakers have much higher impedance than marked. This makes them an easier load than expected. But there are exceptions.
Andreas
#2 Most speakers have much higher impedance than marked. This makes them an easier load than expected. But there are exceptions.
Andreas
sajti said:
Hey Satji, Do you remember what value of emmitter resisters ML used with the three paralell drivers?
K-amps said:
I just get the paper
😎
They use 18.2 ohms between the bases of the output devices, 1ohm at the emitter of each 15030, and 10ohms series base resistors for each 15030.
sajti
Andreas W said:
Speaker impeadence is usually frequency dependent. Higher frequencies have higher impeadences due to reactive componants. Testing with a resistive load will not give an acurate representation of the acual output at all frequency range.
Hi cunningham,
Speaker impedance can be anywhere. A tweeter's inductance isn't extremely high compared to a woofer or mid. Sometimes a 4 ohm tweeter is used in an 8 ohm rated speaker. Never mind whatever correction is built into the crossover. Phase angles can be all over the place too. This can make a particular speaker a very quirky load to drive.
For a full range, single speaker, you are correct.
-Chris
Speaker impedance can be anywhere. A tweeter's inductance isn't extremely high compared to a woofer or mid. Sometimes a 4 ohm tweeter is used in an 8 ohm rated speaker. Never mind whatever correction is built into the crossover. Phase angles can be all over the place too. This can make a particular speaker a very quirky load to drive.
For a full range, single speaker, you are correct.
-Chris
Hi sajti , Hi K-amps ,
You guys forgot that the GAIN of MJ15024/25 is very less as compaired to the new devices now avaliable like the TOSHIBA 2SA1943/2SC5200 & ON semiconductor MJL4281A/MJL4302A which have better bandwidth and gain ,
The TOSHIBA 2SA1943/2SC5200 are 150w 230v devices having hfe 55 to160 and the ON semiconductor MJL4281A/MJL4302A are 350v 230w devices rated to have minimum gain of 50 at IC 8A and hfe range is 80 to 240 . Hence the base current of the 10 output pairs will be much less allowing the use of single pair of MJE1503X drivers .
In my amp the max collector current of each output device when using 10 pairs and 800w power output at +/- 90v supply will be less than 200ma .
Andreas W
QSE MX3000 is very reliable , it has been used with respect here since years , although there are complaints in the RMX2450 .
Loudspeakers are NOT easier load than resistors in fact they are worse , I have an old Audio Handbook of National semiconductor from which I will get scanned some interesting text and post it later on thread for you .
With best wishes
Rajeev
You guys forgot that the GAIN of MJ15024/25 is very less as compaired to the new devices now avaliable like the TOSHIBA 2SA1943/2SC5200 & ON semiconductor MJL4281A/MJL4302A which have better bandwidth and gain ,
The TOSHIBA 2SA1943/2SC5200 are 150w 230v devices having hfe 55 to160 and the ON semiconductor MJL4281A/MJL4302A are 350v 230w devices rated to have minimum gain of 50 at IC 8A and hfe range is 80 to 240 . Hence the base current of the 10 output pairs will be much less allowing the use of single pair of MJE1503X drivers .
In my amp the max collector current of each output device when using 10 pairs and 800w power output at +/- 90v supply will be less than 200ma .
Andreas W
QSE MX3000 is very reliable , it has been used with respect here since years , although there are complaints in the RMX2450 .
Loudspeakers are NOT easier load than resistors in fact they are worse , I have an old Audio Handbook of National semiconductor from which I will get scanned some interesting text and post it later on thread for you .
With best wishes
Rajeev
rajeev luthra said:
Not sure where we gave you that impression Rajeev. All I said was if you are driving 8 pairs of outputs into a 2 ohm load, you need to consider the drivers being able to provide enough base current without beta droop related distortions. (Which primarily affects the drivers and not the OP stages in a BJT OP stage.)
Given the TOS devices have better gain than the MJ15024/25 (which I never recommended anyway) it is still not infinite.
With a higher loading on the OP devices, they will begin to load up the drivers which may not blow up, but will certainly react adversely to increased current demands resulting in some audible and some inaudible level of increases in distortion.
There's a reason why Mark Levinsons and Krells used paralell drivers or other hi-current amps use larger drivers.
If you base you design entirely on simple calculations (e.g. for 8 output pairs driving 16 amps with hfe of 50 I need to supply a base current of 320mA or 20mA perdevice....) you run the risk of having a working design that might not sound so good in real life.
A good design considers all variables, and thats why myself and others have stressed that you need an adequate drive. (Adequate does not necessarily mean enough) . 😉
regards,
quasi
10 pairs means 20 devices , and the collector current mentioned was correct .
K-amps
Your contribution is valuable to me , I have learned so much from
everybody , I am attaching the data of the output and driver devices , please see the curves and give me your feedback .
10 pairs means 20 devices , and the collector current mentioned was correct .
K-amps
Your contribution is valuable to me , I have learned so much from
everybody , I am attaching the data of the output and driver devices , please see the curves and give me your feedback .
rajeev luthra said:
Rajeev,
Me thinks the MJE15034/35 are very good parts. Have experienced better bass slam with these than the 15030/31. Also I'd suggest once you have this driver hooked up, try paralelling it with another , at 4 ohm load, you will hear warmer (less fatiguing) sound. At 8 ohm's it will be a toss but still you could get a better defined mid-bass.
K-
Hi
I am sorry I could not post the Data and graphs of the Toshiba output devices as the pdf file was big and not accepted by the forum , however you could directly download it from the Toshiba site . www TOSHIBA Semiconductor Company.htm
How ever I have copied the data as follows :-
TOSHIBA Transistor Silicon NPN Triple Diffused Type
2SC5200
Power Amplifier Applications
•High breakdown voltage: VCEO = 230 V (min)
•Complementary to 2SA1943
•Suitable for use in 100-W high fidelity audio amplifier’s output stage
Maximum Ratings (Tc = 25°C)
Characteristics Symbol Rating Unit
Collector-base voltage VCBO 230 V
Collector-emitter voltage VCEO 230 V
Emitter-base voltage VEBO 5 V
Collector current IC 15 A
Base current IB 1.5 A
Collector power dissipation
(Tc = 25°C) PC 150 W
Junction temperature Tj 150 °C
Storage temperature range Tstg -55 to 150 °C
Electrical Characteristics (Tc = 25°C)
Characteristics Symbol Test Condition Min Typ. Max Unit
Collector cut-off current ICBO VCB = 230 V, IE = 0 ? ? 5.0 µA
Emitter cut-off current IEBO VEB = 5 V, IC = 0 ? ? 5.0 µA
Collector-emitter breakdown voltage V (BR) CEO IC = 50 mA, IB = 0
230 ? ? V
hFE (1)
(Note) VCE = 5 V, IC = 1 A 55 ? 160 DC current gain
hFE (2) VCE = 5 V, IC = 7 A 35 60 ?
Collector-emitter saturation voltage VCE (sat) IC = 8 A, IB = 0.8 A ? 0.4
3.0 V
Base-emitter voltage VBE VCE = 5 V, IC = 7 A ? 1.0 1.5 V
Transition frequency fT VCE = 5 V, IC = 1 A ? 30 ? MHz
Collector output capacitance Cob VCB = 10 V, IE = 0, f = 1 MHz ? 200 ?
pF
Note: hFE (1) classification R: 55 to 110, O: 80 to 160
I hope this Will be helpful .
Rajeev
I am sorry I could not post the Data and graphs of the Toshiba output devices as the pdf file was big and not accepted by the forum , however you could directly download it from the Toshiba site . www TOSHIBA Semiconductor Company.htm
How ever I have copied the data as follows :-
TOSHIBA Transistor Silicon NPN Triple Diffused Type
2SC5200
Power Amplifier Applications
•High breakdown voltage: VCEO = 230 V (min)
•Complementary to 2SA1943
•Suitable for use in 100-W high fidelity audio amplifier’s output stage
Maximum Ratings (Tc = 25°C)
Characteristics Symbol Rating Unit
Collector-base voltage VCBO 230 V
Collector-emitter voltage VCEO 230 V
Emitter-base voltage VEBO 5 V
Collector current IC 15 A
Base current IB 1.5 A
Collector power dissipation
(Tc = 25°C) PC 150 W
Junction temperature Tj 150 °C
Storage temperature range Tstg -55 to 150 °C
Electrical Characteristics (Tc = 25°C)
Characteristics Symbol Test Condition Min Typ. Max Unit
Collector cut-off current ICBO VCB = 230 V, IE = 0 ? ? 5.0 µA
Emitter cut-off current IEBO VEB = 5 V, IC = 0 ? ? 5.0 µA
Collector-emitter breakdown voltage V (BR) CEO IC = 50 mA, IB = 0
230 ? ? V
hFE (1)
(Note) VCE = 5 V, IC = 1 A 55 ? 160 DC current gain
hFE (2) VCE = 5 V, IC = 7 A 35 60 ?
Collector-emitter saturation voltage VCE (sat) IC = 8 A, IB = 0.8 A ? 0.4
3.0 V
Base-emitter voltage VBE VCE = 5 V, IC = 7 A ? 1.0 1.5 V
Transition frequency fT VCE = 5 V, IC = 1 A ? 30 ? MHz
Collector output capacitance Cob VCB = 10 V, IE = 0, f = 1 MHz ? 200 ?
pF
Note: hFE (1) classification R: 55 to 110, O: 80 to 160
I hope this Will be helpful .
Rajeev
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