So, looking at the 11cm diameter & 5.5cm height of transfo as quoted above, what do you think about the amps true power output @ 4,6,8 ohms?
Here is the rear view of the amp:
http://www.freeimagehosting.net/newuploads/a80d7.jpg
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Like I said, about 40W continuous is what you should be able to expect per channel.
And 40W is not a small amount of power either.
The amp itself can swing larger voltages. With 30V rails you should theoretically get over 130W of power. Unfortunately you are limited by dissipation, and in this case the amplifier may be able to survive only with lower power into lower impedance as the sink cannot handle more than about 70-80W of heat.
A Symphonic Line RG-10 uses two pairs of these transistors in the output, and has about twice the heatsink area per channel. It is rated to 130W x 8 ohm and 180W x 4 ohm.
One pair of these cannot handle more than about 100W output. Into any load.
And 40W is not a small amount of power either.
The amp itself can swing larger voltages. With 30V rails you should theoretically get over 130W of power. Unfortunately you are limited by dissipation, and in this case the amplifier may be able to survive only with lower power into lower impedance as the sink cannot handle more than about 70-80W of heat.
A Symphonic Line RG-10 uses two pairs of these transistors in the output, and has about twice the heatsink area per channel. It is rated to 130W x 8 ohm and 180W x 4 ohm.
One pair of these cannot handle more than about 100W output. Into any load.
Goodness me!!!🙁
Then why Norge rate it at 125W X 2 @ 4 ohms.
It is just a plain lie then.😱
well thew could have claimed 1000W PMPO...
The schematic design likely allows that output, but the thermal design (heatsink) says no.
The schematic design likely allows that output, but the thermal design (heatsink) says no.
digits, do a pair of A1943/C5200 have a maximum capacity of 100 watts @ 4 ohms? I have downloaded the toshiba datasheet and it is saying 150 watts.
You realy don't want to run them at their max threshold.
At the very minimum, if you do not change anything, then avoid 4 ohm loads.
At the very minimum, if you do not change anything, then avoid 4 ohm loads.
I have come up with a device rating rule for the output stage of a ClassAB amplifier.
I have arrived at this by carefully assessing much of the advice posted on this Forum and from modeling and experiments conducted by myself.
For a maximum output power of Y Watts then provide
4timesY for mosFET power devices
5 to 6timesY for BJT power devices.
Check for de-rated SOA of BJTs when supply rail voltage exceeds the knee in the SOA curve
eg.
Target output power is 100W into 8ohms.
Use 400W of mosFETs, i.e. a single pair of 200W devices or a 2pair stage of 100W devices.
or:
Use 500W to 600W of BJTs, i.e. a 2pair stage of 125W to 150W devices or a 3pair stage of 100W devices. BUT, you must check the de-rated SOA if the supply voltage exceeds the knee of the device SOA. A 100W into 8r0 amplifier generally runs at +-50Vdc. a 2sa1943/c5200 pair has the SOA knee @ <<50Vce.
These output device ratings exceed many of the usual recommendations for domestic amplifiers. I believe that these ratings will allow both PA and domestic amplifiers to operate reliably. Just adjust the heatsink size to suit the proposed duty.
Working backwards from a single pair of Toshiba 2sa1943/5200 which have a total power rating of 300W.
Expect the maximum amplifier power to be ~50W to 60W into 8r0.
I have arrived at this by carefully assessing much of the advice posted on this Forum and from modeling and experiments conducted by myself.
For a maximum output power of Y Watts then provide
4timesY for mosFET power devices
5 to 6timesY for BJT power devices.
Check for de-rated SOA of BJTs when supply rail voltage exceeds the knee in the SOA curve
eg.
Target output power is 100W into 8ohms.
Use 400W of mosFETs, i.e. a single pair of 200W devices or a 2pair stage of 100W devices.
or:
Use 500W to 600W of BJTs, i.e. a 2pair stage of 125W to 150W devices or a 3pair stage of 100W devices. BUT, you must check the de-rated SOA if the supply voltage exceeds the knee of the device SOA. A 100W into 8r0 amplifier generally runs at +-50Vdc. a 2sa1943/c5200 pair has the SOA knee @ <<50Vce.
These output device ratings exceed many of the usual recommendations for domestic amplifiers. I believe that these ratings will allow both PA and domestic amplifiers to operate reliably. Just adjust the heatsink size to suit the proposed duty.
Working backwards from a single pair of Toshiba 2sa1943/5200 which have a total power rating of 300W.
Expect the maximum amplifier power to be ~50W to 60W into 8r0.
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Well this is the latest info i was able to gather regarding the amp. And yes this CKT A1943/C5200 transistors belong to Taiwan. Do not know the manufacturer yet.
1: the primary fuse rating. :T3AL250V.EI
2: the physical dimensions of the transformer.: Diameter: 11 cm, Height: 6 cm
3: the rating of the secondary rectifier diodes:
i) Secondary +/- 30V --> Diodes used is two pairs of 6A4 MIC, Caps: two pairs of 4700uF, 50V --> goes to power amp
ii) Secondary +/- 15V --> Diodes used is two pairs of "MIC", Caps: two pairs of 1000uF, 25V --> goes to pre amp
4: the amplifier module fuse ratings: Each of these A1943 or C5200 have one T3AL250V.EI fuse. Total 4 fuse for four transistors.
Transformer pics:
http://www.freeimagehosting.net/2e8f6
http://www.freeimagehosting.net/6a9f6
http://www.freeimagehosting.net/93324
Diodes at +/-30V rails:
http://www.freeimagehosting.net/0e778
Internal layout:
http://www.freeimagehosting.net/7c158
http://www.freeimagehosting.net/7b4db
Heatsink:
http://www.freeimagehosting.net/29d90
I am very curious to find out the true power output of the amp. Also the VA rating of the toroid.
Thanks in advance🙂
1: the primary fuse rating. :T3AL250V.EI
2: the physical dimensions of the transformer.: Diameter: 11 cm, Height: 6 cm
3: the rating of the secondary rectifier diodes:
i) Secondary +/- 30V --> Diodes used is two pairs of 6A4 MIC, Caps: two pairs of 4700uF, 50V --> goes to power amp
ii) Secondary +/- 15V --> Diodes used is two pairs of "MIC", Caps: two pairs of 1000uF, 25V --> goes to pre amp
4: the amplifier module fuse ratings: Each of these A1943 or C5200 have one T3AL250V.EI fuse. Total 4 fuse for four transistors.
Transformer pics:
An externally hosted image should be here but it was not working when we last tested it.
http://www.freeimagehosting.net/2e8f6
An externally hosted image should be here but it was not working when we last tested it.
http://www.freeimagehosting.net/6a9f6
An externally hosted image should be here but it was not working when we last tested it.
http://www.freeimagehosting.net/93324
Diodes at +/-30V rails:
An externally hosted image should be here but it was not working when we last tested it.
http://www.freeimagehosting.net/0e778
Internal layout:
An externally hosted image should be here but it was not working when we last tested it.
http://www.freeimagehosting.net/7c158
An externally hosted image should be here but it was not working when we last tested it.
http://www.freeimagehosting.net/7b4db
Heatsink:
An externally hosted image should be here but it was not working when we last tested it.
http://www.freeimagehosting.net/29d90
I am very curious to find out the true power output of the amp. Also the VA rating of the toroid.
Thanks in advance🙂
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The Thumbnails do not open up.
Did you attach bigger pics?
It looks like you used a remote server to hold the pics
+-30Vdc for unloaded supply rails suggests a maximum output voltage of ~24Vpk into 8r0 and ~20Vpk into 4r0.
these are ~powers of 36W into 8ohms and 50W into 4ohms.
Both those output predictions are within the capability of a pair of genuine Toshiba 2sa1943/c5200 if fitted with an appropriate heatsink.
The pic shows a two channel sink that would suit domestic listening (not party time) for 8ohm speakers.
I would not attach 4ohms speakers and particularly not for a party.
The manufacturer's specification for output power should specify how they measured the quoted value of 125W. I suspect they do not specify the testing method because they have something to hide (that they tell lies) !!!
For a real 50W+50W amplifier I would expect to use a 200VA transformer. I would expect a penny pinching manufacturer to use a 100VA to 150VA transformer.
For that 100VA transformer fitted with a soft start circuit I would use a T1A mains fuse. I would also use F1A fuses to each output device for 8ohm speakers and upgrade these to F1.6A for 4ohm use and check the device temperatures regularly until you know what listening it can survive with.
Did you attach bigger pics?
It looks like you used a remote server to hold the pics
+-30Vdc for unloaded supply rails suggests a maximum output voltage of ~24Vpk into 8r0 and ~20Vpk into 4r0.
these are ~powers of 36W into 8ohms and 50W into 4ohms.
Both those output predictions are within the capability of a pair of genuine Toshiba 2sa1943/c5200 if fitted with an appropriate heatsink.
The pic shows a two channel sink that would suit domestic listening (not party time) for 8ohm speakers.
I would not attach 4ohms speakers and particularly not for a party.
The manufacturer's specification for output power should specify how they measured the quoted value of 125W. I suspect they do not specify the testing method because they have something to hide (that they tell lies) !!!
For a real 50W+50W amplifier I would expect to use a 200VA transformer. I would expect a penny pinching manufacturer to use a 100VA to 150VA transformer.
For that 100VA transformer fitted with a soft start circuit I would use a T1A mains fuse. I would also use F1A fuses to each output device for 8ohm speakers and upgrade these to F1.6A for 4ohm use and check the device temperatures regularly until you know what listening it can survive with.
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@Andrew: 30V transformer, not rails.
@Rishi: Are you in Calcutta, and are you running these with those Sony speakers I saw in another Indian forum?
@Rishi: Are you in Calcutta, and are you running these with those Sony speakers I saw in another Indian forum?
I get them opening at the same size 150x112 pixels.
Stop using the remote server.
Attach your pics to your post.
Stop using the remote server.
Attach your pics to your post.
four times he tells us +/-30V
He has not typed 30+30Vac, nor +-30Vdc.
Ambiguous or what?
Don't click on the Thumbnail.
Don't open the Thumbnail in a new Tab.
Don't open the Thumbnail in a new Window.
Just ask your computer to go and download from an untested site !!!!!!
No Thanks.
Don't open the Thumbnail in a new Tab.
Don't open the Thumbnail in a new Window.
Just ask your computer to go and download from an untested site !!!!!!
No Thanks.
Thanks AndrewT, you provided the real truth of this amp to a noob like me. So, it becomes clear that this amp is 50W + 50W @ 4 ohms amp.
Any idea of the VA of the toroid after looking at the enlarged pics?
Yep from Kolkata. The latest pics are from my amp. I bought it after hearing my friends one which is 4 years old and blown. Can you tell us a place where we can replace this transistors?
I tried what you said. But the pics are not opening. But it is working in other forums. So, have to include the links below the pics.
Sorry for the inconvenience.
Thanks man. 🙂
What will be the relative cost of a pair? Have you seen the enlarged pics i included.
I searched some transformer manufactures like Miracle and at that size(11cm X 6 cm) the have toroid of 300VA.
Can this toroid be 300VA?
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