Hellohi friends
i built a 2.1ch system for my com A few months ago:
2*sr100 amplis
psu-10
zobel network
+33/-33 2a traffo
1.2 kva detex smps(Under Construction)
1500w class d ampli from detex(for subwoofer)
and apex vu meter
the sound quality is very good and detailed
i have a problem
when signal source is connected and audio volume is 30% and upper sound is good and not problem but when audio volume is 0% my traffo gets hot after one hour!
why?
respectfully
This is not the expected response but if the volume is zero for 1 hour to not hear music, turn off the amplifier and the transformer will not heat up.
thanksHello
This is not the expected response but if the volume is zero for 1 hour to not hear music, turn off the amplifier and the transformer will not heat up.
but
This is not a good way
i want solved this problem But I do not know how
what is your opinion mr mile???hi friends
i built a 2.1ch system for my com A few months ago:
2*sr100 amplis
psu-10
zobel network
+33/-33 2a traffo
1.2 kva detex smps(Under Construction)
1500w class d ampli from detex(for subwoofer)
and apex vu meter
the sound quality is very good and detailed
i have a problem
when signal source is connected and audio volume is 30% and upper sound is good and not problem but when audio volume is 0% my traffo gets hot after one hour!
why?
View attachment 626644
View attachment 626645
View attachment 626646
respectfully
Hi behrad. Your pics show a lot of loose, unshielded or untwisted wiring and I suggest that you may have some instability or oscillation when the volume pot. is set low or at zero volume. Oscillation can and will cause the power amplifier to overheat, even though the speakers cannot respond to the output, which may be in the region of 300kHz - several Mhz. The proper way to identify such problems is with an oscilloscope but assuming you don't have or have access to one, you will have to work by trial and temperature - even though the result may still be uncertain.
First though, experiment with grounding (shorting) the input to the offending power amplifier, which should stop any problem with the effect of the volume control, wherever that is located in the overall scheme. Then if that proves effective, it is a matter of reducing the length of all the wiring to make a tidy arrangement where signal and power leads do not radiate signals and noise between them and other sensitive circuits. Take the time to tightly twist the +/- or feed and return pairs of power supplies, output and input signal leads to ensure the cancellation of excess noise and signal that they radiate and receive.
First though, experiment with grounding (shorting) the input to the offending power amplifier, which should stop any problem with the effect of the volume control, wherever that is located in the overall scheme. Then if that proves effective, it is a matter of reducing the length of all the wiring to make a tidy arrangement where signal and power leads do not radiate signals and noise between them and other sensitive circuits. Take the time to tightly twist the +/- or feed and return pairs of power supplies, output and input signal leads to ensure the cancellation of excess noise and signal that they radiate and receive.
Hi Mr. Mile and Mr. Prasi,
Can we use this PCB with SR 200 having Rail Voltage 68-0-68 Vdc?
Regards,
Samrat
Attachments
I often read your comments on how to measure amplifier output transistors and find that although they are theoretically valid, they do not find any application in the real world, simply because no amplifier manufacturer, I speak of NAD, Rotel, Yamaha, Nakamichi or any other brand can come to mind, use those rules to dimension the power stage.
The practical reason why NAD for example declares stable its amplifiers @2ohm with a simple couple of Toshiba 2SC5200 and 2SA1943 is because the music content of any kind is NOT continuous, Almost every commercial amplifier (99%) has a declared response curve that is almost never DC-20000, but 20-20000, amplifiers are amplifiers, power supplies are another thing, even if they want to refer to a track 10HZ (!!!) we find a period of 100 ms, for example:
SOA 2SC5200 at 40V DC (domestic use as many amplifiers in forum discussions) 3,7A = 150watt
SOA 2SC5200 at 40V 100ms (unrealistic 10hz track) 7,5A = 300watt(!!!)
TEN hertz!
And here's why a Toshiba's complementary pair can declare it safe with a 2 ohm load in real-time music use, without forgetting the fact that, apart from the diyers, no one uses test tracks in their own system.
I personally tried to break several times a toshiba pair with a 40V dual supply and 1ohm resistive load (ONE OHM) and nothing, they are still alive.
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hi Mr. AndrewT,
may i ask something since i have read previous posts and you often questioned apex's design reliability when using 1943/5200 rather MJL/W 21193/4
my question is, does MJL/W 21193/4 are really 250W 250V devices as you used in your computation because as i see on the datasheet it's 250V 200W case340G and even MJL4281A and MJL4302A are 350V 230W only.
or do you mean MJ21193/4 in TO−204AA (TO−3)case which are 250V 250W Devices.
im just a little confused...
thank you and regards
may i ask something since i have read previous posts and you often questioned apex's design reliability when using 1943/5200 rather MJL/W 21193/4
my question is, does MJL/W 21193/4 are really 250W 250V devices as you used in your computation because as i see on the datasheet it's 250V 200W case340G and even MJL4281A and MJL4302A are 350V 230W only.
or do you mean MJ21193/4 in TO−204AA (TO−3)case which are 250V 250W Devices.
im just a little confused...
thank you and regards
sir mile i have attached here the PSU-10 idea i do not know if it is right or what is the right PSU upgrade because i am planning to have sr200 with 5pairs on my next project since SR800 is not posible DIY . i do not know if this 2-pair PSU is enough for 10pcs MJL21193/4 O/Ps. and 2xPSU-10 in parallel for a single channel might not good as well.
that red marks indicate the additional output pair and 2x10,000uf, further is it necessary to place another 2x10,000uf marked yellow. and what changes do i need to do then.
And/Or simply what regulated PSU will be enough to handle 5 output pairs of MJL21193/4 moreover should MJE15032/3 instead of c4973/a1837 drivers?
i'm sorry for being delighted on your designs i love doing it before summer vacation ends.
thank you
regards
that red marks indicate the additional output pair and 2x10,000uf, further is it necessary to place another 2x10,000uf marked yellow. and what changes do i need to do then.
And/Or simply what regulated PSU will be enough to handle 5 output pairs of MJL21193/4 moreover should MJE15032/3 instead of c4973/a1837 drivers?
i'm sorry for being delighted on your designs i love doing it before summer vacation ends.
thank you
regards
MJL are the plastic package.
MJ are the metal package.
They have different Tjmax.
If you are interested, compare the 150W 150degrees C 2n3773 to the 150W 150degrees C 2sc5200
The ancient metal package of the 2n3773 is guaranteed by 100% testing to pass 1.5A @ 100Vce
The 5200 can only manage 0.38A @ 100Vce and that is not guaranteed.
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yes sir metal package is more reliable than plastic
but my question is. as you show computations you often refered mjl21193/4 as 250watt devices. wherein as i shop those device before and have the datasheet it is 250V 200W only.
i am clarifying these because i want to make sure we mean the same thing especially in computing the output power.
i have tried both MJ21193/4 and MJL21193/4. and i only use those metal based trannies if i have suitable heatsink.
thanks
regards.
but my question is. as you show computations you often refered mjl21193/4 as 250watt devices. wherein as i shop those device before and have the datasheet it is 250V 200W only.
i am clarifying these because i want to make sure we mean the same thing especially in computing the output power.
i have tried both MJ21193/4 and MJL21193/4. and i only use those metal based trannies if i have suitable heatsink.
thanks
regards.
MJL is the plastic package, not the metal package.
"you show computations you often refered mjl21193/4 as 250watt devices",
I don't think so, Show me where and I'll see if the Moderators are willing to remove/change the error.
