🙄 CONFUSED
I'M PLANNING TO ASSEMBLE AN AMP WITH 2SC5200/2SC1943
AND A PLUS/MINUS 78VDC AT THE RAILS. IS IT SAFE FOR THESE DEVICES WITH THAT SUPPLY RAILS?
AM I KILLING THEM? BUT IF POSSIBLE HOW MANY OF THESE DEVICES WILL I USE BETWEEN THE RAILS?
HIENRICH
I'M PLANNING TO ASSEMBLE AN AMP WITH 2SC5200/2SC1943
AND A PLUS/MINUS 78VDC AT THE RAILS. IS IT SAFE FOR THESE DEVICES WITH THAT SUPPLY RAILS?
AM I KILLING THEM? BUT IF POSSIBLE HOW MANY OF THESE DEVICES WILL I USE BETWEEN THE RAILS?
HIENRICH
You'll be absolutely fine with this power supply voltage of +-78VDC. These transistors can handle up to 230V, you're total power supply voltage is only 156 so there's no problem as far as too much voltage being on the transistors.
As far as how many to put in parallel for your speaker, lets see.
If you're doing 8 ohm load, then you'll probably get about 300W at that voltage. This means that at worst, the transistors dissipate about 200W(half swing). They'll have to also deal with 10A if you deliver a square wave at full clip into a resistive load. Turn this load into a speaker and that could become a lot more. Let's say about 18A to be safe. Being that these devices are good for 15A, it is simply a must to at least use two pairs in a channel.
Being that these devices are 150W each and 15A, I would say that four pairs are needed to be relatively safe.
On a 4 ohm load, you'll need a lot more.
As far as how many to put in parallel for your speaker, lets see.
If you're doing 8 ohm load, then you'll probably get about 300W at that voltage. This means that at worst, the transistors dissipate about 200W(half swing). They'll have to also deal with 10A if you deliver a square wave at full clip into a resistive load. Turn this load into a speaker and that could become a lot more. Let's say about 18A to be safe. Being that these devices are good for 15A, it is simply a must to at least use two pairs in a channel.
Being that these devices are 150W each and 15A, I would say that four pairs are needed to be relatively safe.
On a 4 ohm load, you'll need a lot more.
hienrich said:🙄 CONFUSED
I'M PLANNING TO ASSEMBLE AN AMP WITH 2SC5200/2SC1943
AND A PLUS/MINUS 78VDC AT THE RAILS. IS IT SAFE FOR THESE DEVICES WITH THAT SUPPLY RAILS?
AM I KILLING THEM? BUT IF POSSIBLE HOW MANY OF THESE DEVICES WILL I USE BETWEEN THE RAILS?
HIENRICH
Hi Hienrich,
happy new year!
You can use 2SC1943/2SA5200 even at +-140VDC rails without any type of destruction.
QSC exculsively use these trannies at +-150VDC
Regards,
Kanwar
Re: Re: 2sc5200/2sa1493 With +/- 78vdc ?
N E V E R ! ! !
They will blow in the first second of driving beyond their voltage capacity!
QSC uses them in class H configuration!
Class H (and Class G) is not comparable to Class B concerning supply rails.
Uli
Workhorse said:
N E V E R ! ! !
They will blow in the first second of driving beyond their voltage capacity!
QSC uses them in class H configuration!
Class H (and Class G) is not comparable to Class B concerning supply rails.
Uli
haha, uli, I think he might mean 140V P-P, thus, +-70V rails.
+-140V would be 280P-P, and yes, that would destroy the transistor instantly as the swing approached 230.
Also, +-140 would yield about 1080Wrms into 8ohms. Might need just a few of these transistors in that situation even if they did that voltage. lol.
I do think, though, that people should be very specific whether they mean +-140 or +-70 being 140V rails.
I hope I clarified helpfully😉
EDIT: And if workhorse did mean actualy +-140V rails. hahaha.... ouch for those transistors.
+-140V would be 280P-P, and yes, that would destroy the transistor instantly as the swing approached 230.
Also, +-140 would yield about 1080Wrms into 8ohms. Might need just a few of these transistors in that situation even if they did that voltage. lol.
I do think, though, that people should be very specific whether they mean +-140 or +-70 being 140V rails.
I hope I clarified helpfully😉
EDIT: And if workhorse did mean actualy +-140V rails. hahaha.... ouch for those transistors.
QSC uses these transistors in such an arrangement that they are never exposed to more than 60V Vce when conducting [altough the 230V blocking capability is still required when not conducting]
For standard sagging +-78V rails use two pairs as an absolute minimum for 8 ohms loads and three pairs as an absolute minimum for 4 ohms loads
Feel free to add additional pairs, but be careful since there is a big fake market of 2SC5200/2SA1943 and the fake units have very poor dissipation capabilities [you would probably need 10 or more fake pairs for reliable operation at 4 ohms...]
For standard sagging +-78V rails use two pairs as an absolute minimum for 8 ohms loads and three pairs as an absolute minimum for 4 ohms loads
Feel free to add additional pairs, but be careful since there is a big fake market of 2SC5200/2SA1943 and the fake units have very poor dissipation capabilities [you would probably need 10 or more fake pairs for reliable operation at 4 ohms...]
yes eva knows the business.
Those absolute minimums are definitley minimums of course. Wouldn't want to accidentaly put 4ohms on an amp with just two pairs lol.
Those absolute minimums are definitley minimums of course. Wouldn't want to accidentaly put 4ohms on an amp with just two pairs lol.
Hi,
No one has mentioned SOA curves for these devices YET.
5200/1943 are not particularly good above 60volts.
SOA shows absolute maximum DC current of 650mA @ 80volts.
This will apply to the transistor with the highest current draw in a parallel output. I would suggest that for short circuit condition you allow a maximum current per output transistor of between 50% and 70% of maximum say 400mA. 4 pairs will only carry 1.6amps. Again I suggest this is far too low for a 300w amp.
Next design consideration is maximum power. Current peak (Ipk) is about 78volts divided by 8 ohms giving 9.75 amps.
I recommend you design for Ipk at half supply volts to allow for inductive or capacitive loading into real 8 ohm speakers. This results in your ouput transistors carrying 9.75A @ 39v. 4 pairs give only a 25% margin at this voltage.
But the problem gets worse; you should consider designing the output stage and drivers for about half the intended load impedance which will double all the currents considered so far, and finally would you ever want to drive 4 ohm speakers or 2 *8ohms in parallel? then you have to quadruple all the currents.
We are not finished yet, you will be running quiescent current in the output stage? Then it follows that the transistors are at elevated temperatures. All the SOA data is based on a case temperature (Tc) of 25deg C. you now have to apply a reduction factor on all your design data at a fair guestimate of your running temp at the hottest time of the year and with maximum voltage coming from your electricity supplier.
I DO NOT recommend 1943/5200 at these rail volts!
Please do not suggest rails above 100volts without thinking (designing) of the consequences for the originator of this thread.
regards Andrew T.
No one has mentioned SOA curves for these devices YET.
5200/1943 are not particularly good above 60volts.
SOA shows absolute maximum DC current of 650mA @ 80volts.
This will apply to the transistor with the highest current draw in a parallel output. I would suggest that for short circuit condition you allow a maximum current per output transistor of between 50% and 70% of maximum say 400mA. 4 pairs will only carry 1.6amps. Again I suggest this is far too low for a 300w amp.
Next design consideration is maximum power. Current peak (Ipk) is about 78volts divided by 8 ohms giving 9.75 amps.
I recommend you design for Ipk at half supply volts to allow for inductive or capacitive loading into real 8 ohm speakers. This results in your ouput transistors carrying 9.75A @ 39v. 4 pairs give only a 25% margin at this voltage.
But the problem gets worse; you should consider designing the output stage and drivers for about half the intended load impedance which will double all the currents considered so far, and finally would you ever want to drive 4 ohm speakers or 2 *8ohms in parallel? then you have to quadruple all the currents.
We are not finished yet, you will be running quiescent current in the output stage? Then it follows that the transistors are at elevated temperatures. All the SOA data is based on a case temperature (Tc) of 25deg C. you now have to apply a reduction factor on all your design data at a fair guestimate of your running temp at the hottest time of the year and with maximum voltage coming from your electricity supplier.
I DO NOT recommend 1943/5200 at these rail volts!
Please do not suggest rails above 100volts without thinking (designing) of the consequences for the originator of this thread.
regards Andrew T.
Duo said:
Hi Duo,
imagine rails at +-65V constant is 130V pp. add another +-85V
which are activated in class G or H then you reach +150V, -65V
or +65V, -150V. this is 215pp then it works (see Crest, QSC etc).
Uli
PS: in pro audio there are awful lots of outputpairs used!
Yes, I understand that in class G or H you can have a swing not allowable in a normal full swing amplifier. Thus allowing the use of 230V transistors in a system with a theoretical swing of 300V.
I see valid points AndrewT, but one idea: As the voltage across the transistor increases, the current decreases until the crossing point. We start at 78V with just Q current, and would have to move down by 12.8V to achieve the maximum 80V current of 1.6A for four transistors on 8 ohms. Obviously, this 1.6A (400mA) is now at 65.2V across the transistor (in a world with no power supply droop. Add in supply drooping/sagging, and you get even less voltage across the transistor. I imagine in this situation that the SOA would rarely be exceeded...
Of course, as far as reactive loads and heat are concerned, there is definitely area to be careful.
I see valid points AndrewT, but one idea: As the voltage across the transistor increases, the current decreases until the crossing point. We start at 78V with just Q current, and would have to move down by 12.8V to achieve the maximum 80V current of 1.6A for four transistors on 8 ohms. Obviously, this 1.6A (400mA) is now at 65.2V across the transistor (in a world with no power supply droop. Add in supply drooping/sagging, and you get even less voltage across the transistor. I imagine in this situation that the SOA would rarely be exceeded...
Of course, as far as reactive loads and heat are concerned, there is definitely area to be careful.
max. power
imagine driving this amp with 2/pi of the maximum voltage,
this is about 50 volts. assuming a resistive loade this is
6.25 A into 8 R.
the 2SC5200 is only capable of delivering 5 A at 30V (~80-50).
this means that you have to use at least 2 pairs, better 3 pairs.
IMHO there exist better hi power transistors than the 2SC5200.
I prefer the 2SC3264/2SA1295 combo. It is fast and reliable
A N D there are no fakes known of those Sanken devices!
Uli
imagine driving this amp with 2/pi of the maximum voltage,
this is about 50 volts. assuming a resistive loade this is
6.25 A into 8 R.
the 2SC5200 is only capable of delivering 5 A at 30V (~80-50).
this means that you have to use at least 2 pairs, better 3 pairs.
IMHO there exist better hi power transistors than the 2SC5200.
I prefer the 2SC3264/2SA1295 combo. It is fast and reliable
A N D there are no fakes known of those Sanken devices!
Uli
Well, obviously there are better transistors around than this for the job. We are just trying to help with a case involving just the original transistors stated.
If I had my way, I'd use some MJ21193/21194 or similar onsemis in my amp😉
If I had my way, I'd use some MJ21193/21194 or similar onsemis in my amp😉
Duo said:
You are right, but in the first post there is stated a "planned"
amp so I think good advice is to start with another transistor
couple.
Uli
PS: those motorolas are like diesel engines 😀
powerful but SLOW
Of course. If one might be able to scrape the slate for new specification in transistors, I'd definitley not mess around with the 1943/5200 pair.
As far as 21193/21194, yes, not the fastest, but bloody indestructable compared to most transistors.
For faster ones though, onsemi has some really fast transistors that'll take as much beating. 😉
EDIT: Yes, the MJL4281/4302 pair are very nice. Wicked SOA and fast like an oiled pig.
As far as 21193/21194, yes, not the fastest, but bloody indestructable compared to most transistors.
For faster ones though, onsemi has some really fast transistors that'll take as much beating. 😉
EDIT: Yes, the MJL4281/4302 pair are very nice. Wicked SOA and fast like an oiled pig.
change my mind
🙂 🙂
ok, ok, I change my mind. Upon going with the thread, and lists of
expert advice and mathemathics from you guys. I change my mind.
I'd rather go for MJL's, so I will never have problems unlocking our old
expired fire extinguisher.
with MJL's, maybe I could go more farther than +/- 78vdc or even go as far as +/- 96vdc. Sankens are too expensive.
Actually by this time, I'm still in the process with my new project.
Hey hobbyists, audio freaks check this out.
http://www.eserviceinfo.com/downloadsm/5170/rotel_rb1090.html
🙂 🙂 🙂
HIENRICH
🙂 🙂
ok, ok, I change my mind. Upon going with the thread, and lists of
expert advice and mathemathics from you guys. I change my mind.
I'd rather go for MJL's, so I will never have problems unlocking our old
expired fire extinguisher.
with MJL's, maybe I could go more farther than +/- 78vdc or even go as far as +/- 96vdc. Sankens are too expensive.
Actually by this time, I'm still in the process with my new project.
Hey hobbyists, audio freaks check this out.
http://www.eserviceinfo.com/downloadsm/5170/rotel_rb1090.html
🙂 🙂 🙂
HIENRICH
Reply
Hi ULI & DUO
Class-H is similar to Class-AB Except there are 2 or more power Supply TIER's are present. In this situation If the output swing is less than the Reference voltage then the lower rail is used and when it exceeds the reference point the high voltage rail is switched on by switching Mosfets in rails. This Class-H simply increases the efficiency a little bit.This simply ellaborates that the trannies are very well exposed to high voltage.
QSC uses +140 & -140 rails for high voltage swings.
Regards
Kanwar
Hi ULI & DUO
Class-H is similar to Class-AB Except there are 2 or more power Supply TIER's are present. In this situation If the output swing is less than the Reference voltage then the lower rail is used and when it exceeds the reference point the high voltage rail is switched on by switching Mosfets in rails. This Class-H simply increases the efficiency a little bit.This simply ellaborates that the trannies are very well exposed to high voltage.
QSC uses +140 & -140 rails for high voltage swings.
Regards
Kanwar
Here is the link Schematic of RMX1850 Model of QSC
Clarify your doubts
http://www.qscaudio.com/support/library/schems/rmx4050.pdf
regards
Kanwar
Clarify your doubts
http://www.qscaudio.com/support/library/schems/rmx4050.pdf
regards
Kanwar
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