I am planning on making powerfull sub woofer amp nearly (600-1000W RMS)
I am including a circuit which i know works very well cause i designed it and has very good sonics .......
I need to know the following :-
1.How much voltage can be used in this amp safety ?
2.need help in reconfiguring the bias control scheme
3.Wat modification r needed.........
4.R the output & drivers good enough?
circuit
regards
sekhar
I am including a circuit which i know works very well cause i designed it and has very good sonics .......
I need to know the following :-
1.How much voltage can be used in this amp safety ?
2.need help in reconfiguring the bias control scheme
3.Wat modification r needed.........
4.R the output & drivers good enough?
circuit
An externally hosted image should be here but it was not working when we last tested it.
regards
sekhar
You wont need the zener, thats just me being overprotective.
An externally hosted image should be here but it was not working when we last tested it.
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HI, is this the way it should be and does the bias tranistor needs to sit on main heatsink ?????and wat is the maximum voltage applicable......??????
circuit
An externally hosted image should be here but it was not working when we last tested it.
regards
sekhar
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Is it me or would the 1n4007's across the Vbe multiplier limit the bias to barely on? Good safety for open wiper as originally drawn, like Nigel's zener. It just strikes me as too safe.
How much rail voltage the amp can handle depends on a number of factors, including the load, your heat sinks, your isolator choice and a few other things. Pull out the data sheet for your outputs and take a look at the safe operating area curves. Just a guess, but with 4 pairs of outputs, you should probably limit your rails to +/-60V or so. With 4 pairs of plastic outputs you should think 200W/ 8R max.
Output device Safe Operating Area (SOA) will be your main factor determining the maximum rail voltage your chosen design can handle - especially for Subwoofer duty which tends to be high power and low impedance. There are plenty of threads here discussing SOA calculations. Time to read.
For 600-1000 W out into 4 ohms (or is it 2?) you should have at least 8 pairs of outputs, if not 12. The more heat sink you have the fewer you can live with but reliability will be better with more. You may need to update the driver section to handle the increased drive current needed by the additional outputs.
I probably should have mentioned this first, but if this is your first amplifier build, for safety you should probably do something smaller first or buy something like HPA-NXV1200 1200 watt MOSFET Audio Amplifier Module The rail voltages needed for 1,000W are potentially lethal. In the US there are plenty of PA amp choices that work well for subwoofer duty that can be purchased for well below the cost of building something reliable yourself. Maybe you can find something used.
How much rail voltage the amp can handle depends on a number of factors, including the load, your heat sinks, your isolator choice and a few other things. Pull out the data sheet for your outputs and take a look at the safe operating area curves. Just a guess, but with 4 pairs of outputs, you should probably limit your rails to +/-60V or so. With 4 pairs of plastic outputs you should think 200W/ 8R max.
Output device Safe Operating Area (SOA) will be your main factor determining the maximum rail voltage your chosen design can handle - especially for Subwoofer duty which tends to be high power and low impedance. There are plenty of threads here discussing SOA calculations. Time to read.
For 600-1000 W out into 4 ohms (or is it 2?) you should have at least 8 pairs of outputs, if not 12. The more heat sink you have the fewer you can live with but reliability will be better with more. You may need to update the driver section to handle the increased drive current needed by the additional outputs.
I probably should have mentioned this first, but if this is your first amplifier build, for safety you should probably do something smaller first or buy something like HPA-NXV1200 1200 watt MOSFET Audio Amplifier Module The rail voltages needed for 1,000W are potentially lethal. In the US there are plenty of PA amp choices that work well for subwoofer duty that can be purchased for well below the cost of building something reliable yourself. Maybe you can find something used.2 minor nitpicks. 1) you have the collectors and emiters reversed on the positive output transistors and 2) The outputs are mislabeled (2sa1943 x 4 should be on the positive side and 2sc5200 should be on the negatives side. Also a questtion going back to the 1n4007 diodes across the bias circuit. It looks like the current limiting circuit won't be able to current limit very well with this bias circuit. Good luck with it.
thanks for pointing out my mistake actually i was out of town for a few days i am uploading the corrected image and with bias arrangement kingly give out ur drawings an suggestion and wat do u think about multi slope vi limiter
corrected circuit
An externally hosted image should be here but it was not working when we last tested it.
regards
Sekhar
eventhough this is another simulator product ....meaning that from simulation to schematic topcb to construction to thermal tests and so on and on its a very very long and painfull way
at 70 volt rails you expect almost 200 w clean power psu depenting also that will be almost double at $ ohms also psu depenting ....
now at this power with a bootstrap and a "basic " ltp input stage you will manage to produce the power, though if this is going to be a Pa amplifier then the design is poor since only a VI limmiter will not protect it enough,,,,
not to mention that pcb has his own rules ...then mechanical and wiring has also its own rules and thermals have also the need for a good design ....
times this with how cost effective is your amp then you have a problem ....
I am not trying to turn you down but PA amlifiers cannot be designed that simply
at 70 volt rails you expect almost 200 w clean power psu depenting also that will be almost double at $ ohms also psu depenting ....
now at this power with a bootstrap and a "basic " ltp input stage you will manage to produce the power, though if this is going to be a Pa amplifier then the design is poor since only a VI limmiter will not protect it enough,,,,
not to mention that pcb has his own rules ...then mechanical and wiring has also its own rules and thermals have also the need for a good design ....
times this with how cost effective is your amp then you have a problem ....
I am not trying to turn you down but PA amlifiers cannot be designed that simply
Sorry to pick and it is a minor point but - most of the worlds PA amplifiers are the simplest, grungiest designs. My experience in having to repair Monatech - Bacus - Studer - Trace Elliot - Electrovoice - Amcron/Crown - Bose - C-Audio - JBL - Tannoy - HH - Carlsbro - Eagle - TOA - Rane - Yamaha - Studiomaster -
They're bigger and can remove your eyebrows if treated with less than the respect they deserve -- but by god they are simple.
You'll find the studio and high end reference hifi designs far more complex - Mark Levinson - the later Krells - Arcam - Carver - Accuphase - Phase Linear - Audio research - Musical Fidelity - Lentek - Theta - Meridian
A dichotomy comes from using PA amplifier principles and simplicity that I experience with NAD - Quad - Naim, yet they do so well in the marketplace.
Sorry Sakis I have fixed that much power PA that I know they are the Tractors of the amplifier world
...the Bugatti Veyron's are Theta and Mark Levinson
in the past PA amlifiers were based on the philosophy you mention .... in the past PA amplifiers ment a Beast ....overdesign ...everything huge state of the art parts and so on
even at that days each and every area of the amp was protected against abuse with some times more than one method
as about these amplifiers sounds stoneage to me never been working with them and if a recall well none of them is doing amps any more and i wonder why
Monatech
Bacus
Studer
Bose
C-Audio
Tannoy
HH
Carlsbro
Eagle
TOA
Studiomaster
as about these amplifiers that i ve been aleady working with many times
Trace Elliot - Electrovoice - Amcron/Crown - Rane - Yamaha JBL i can ashure you that they have inside a gozillion of protection methods
some of them is
very well guarded input ( diodes capacitors filters)
most areas designed with ccs no bootstrap
feedback properly guarded
accurate and safe VBE
probabaly limited bandwidth
multislope VI limmiters
full zobel with inductor
fuses fans and thermostats here and there
some of them like crest even feature LDR input limmiters
and there is going to be more that i don recall right now
now days we moved to class G or H and eventually D
like them or not is another story ...i am very happy with class AB but that's just me ....a 2SA1302 guy as you can see in my avatar
happy regrads sakis
even at that days each and every area of the amp was protected against abuse with some times more than one method
as about these amplifiers sounds stoneage to me never been working with them and if a recall well none of them is doing amps any more and i wonder why
Monatech
Bacus
Studer
Bose
C-Audio
Tannoy
HH
Carlsbro
Eagle
TOA
Studiomaster
as about these amplifiers that i ve been aleady working with many times
Trace Elliot - Electrovoice - Amcron/Crown - Rane - Yamaha JBL i can ashure you that they have inside a gozillion of protection methods
some of them is
very well guarded input ( diodes capacitors filters)
most areas designed with ccs no bootstrap
feedback properly guarded
accurate and safe VBE
probabaly limited bandwidth
multislope VI limmiters
full zobel with inductor
fuses fans and thermostats here and there
some of them like crest even feature LDR input limmiters
and there is going to be more that i don recall right now
now days we moved to class G or H and eventually D
like them or not is another story ...i am very happy with class AB but that's just me ....a 2SA1302 guy as you can see in my avatar
happy regrads sakis
A few protection systems doesnt make the design complex - even the stuff you call stoneage has some of that -- but the majority has soft start some VI and DC output protection -- the rest of it is very yesterday -- there's nothing complex or very new about this at all. I dont think any or all of these protection or compensations are particularly complex in themselves anyhow. Nice though they are - my own preference in designs is to only use what is necessary - rather than cram every style of limiter into a design.
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Hi sekhar
You'll need a few more output transistors
If you want a nice & safe amplifier i'd recommend your output stage can dissipate 4 times the amplifier output power or more. So if you want that 1KW then look to install enough transistors that can dissipate (in theory) 4KW & you should be safe enough.
I'd also think about an output triple to give you enough current gain, it'll also lower distortion. Even if you drive a highish 8 ohm impedance you'll still need a lot of current at those sorts of powers.
You'll need a few more output transistors
If you want a nice & safe amplifier i'd recommend your output stage can dissipate 4 times the amplifier output power or more. So if you want that 1KW then look to install enough transistors that can dissipate (in theory) 4KW & you should be safe enough.I'd also think about an output triple to give you enough current gain, it'll also lower distortion. Even if you drive a highish 8 ohm impedance you'll still need a lot of current at those sorts of powers.
to event horizon
sir, i dont know much about output triple can u show me how is done and how many transistor r needed in the o/p stage to handle 1000W rms and any comment on Multislope Vi limiter included in the circuit....... it is taken from G R.Slone book
I also have dc protection circuit , turn on delay , softstart circuit, temp control fan circuits ready to be used i just want o/p shortcircuit protection circuit will the multislope Vi limiter included help in output shortcircuit protection
regards
sekhar
sir, i dont know much about output triple can u show me how is done and how many transistor r needed in the o/p stage to handle 1000W rms and any comment on Multislope Vi limiter included in the circuit....... it is taken from G R.Slone book
I also have dc protection circuit , turn on delay , softstart circuit, temp control fan circuits ready to be used i just want o/p shortcircuit protection circuit will the multislope Vi limiter included help in output shortcircuit protection
regards
sekhar
The way I see it, your V/I limiter will kick in at ~2.8A. The circuit you copied is designed to sense each output device, not the whole stage.
You still have the bias limiting issue - the 1N4007s will clamp your bias voltage to levels that barely allow the output stage to turn on. You'll have Class B operation unless you substitute a couple of low voltage zeners or increase the string of diodes to at least 4 to allow a little biasing headroom.
Are you planning to mount the Vbe multiplier transistor on the output one of devices?
You'll need to do this or have some other form of temperature compensation to avoid blowing up the output stage.
I would put the 0R33 resistors between the emitter of the 2SA1943s and the 0R5. This would help current sharing in that side of the output stage. I don't see how they help at all where they are, but I am no expert.
For an output triple example, see the Leach amp - it is one of many examples that use a triple darlington output stage.
You still have the bias limiting issue - the 1N4007s will clamp your bias voltage to levels that barely allow the output stage to turn on. You'll have Class B operation unless you substitute a couple of low voltage zeners or increase the string of diodes to at least 4 to allow a little biasing headroom.
Are you planning to mount the Vbe multiplier transistor on the output one of devices?
You'll need to do this or have some other form of temperature compensation to avoid blowing up the output stage.
I would put the 0R33 resistors between the emitter of the 2SA1943s and the 0R5. This would help current sharing in that side of the output stage. I don't see how they help at all where they are, but I am no expert.
For an output triple example, see the Leach amp - it is one of many examples that use a triple darlington output stage.
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THANKS for the suggestion how can i make the VI limiter help me just protect the o/p devices in case of a shortcircuit or being connected to a load 0f 2E i am planning on using the amp at 85V which gives me a rms transformer voltage of 60V so at 4E load it will roughly consume 15A so with my present vi limiter i wont get a proper output as u say it starts limiting at ~2.8A . and can u plz make me understand how does the vbe transistor being mounted on main heatsink prevent the o/p stage from blowing sir kingly dont mind for me asking such question i am just a beginner and these is my first high power amp kindly help.....
regards
sekhar
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