Quote:
You can simply run the PA amp continuously for days non-stop and that too at full level and with ambient temp. around 55C.
I don't know what you are smoking but pass some around please.
A well designed PA amp will run just below clipping and stay alive provided the temp (input air temp is kept within normal bounds).
Any competent sound contractor will specify that the ambient air temp in a rack containing the amplifiers will not exceed a specified level and this is generally around 90-100 degrees max. The higher the temp the shorter the life span of the equipment will be.
In most cases...we air condition the room containing the amp racks and equipment. In one stadium system I did the equipment was in the sign in a special room made of insulated sections. These sections are the same material in which freezers are made of. The room large enough for 3 full size racks with room enough to pull equipment out of the racks and room to walk by the racks was cooled by a 5 ton air conditioner. This was for 55,000 watts of audio power. On a 100 degree day this was able to maintain a temperature of 82-85 degrees in the insulated room. So much for ambient air cooling....
Quote:
You can simply short circuit the ouptut of amp for playing if you dont have access to fire crackers safely because it will not turn up into smoke.
Maybe in your magic kingdom it won't. In the real world it can and does turn to s**t in a heart beat. You never short the output of any amplifier nor do you run a load heavier than what the amplifier is capable of handling.
Just my .02 based on real life experience
You can simply run the PA amp continuously for days non-stop and that too at full level and with ambient temp. around 55C.
I don't know what you are smoking but pass some around please.
A well designed PA amp will run just below clipping and stay alive provided the temp (input air temp is kept within normal bounds).
Any competent sound contractor will specify that the ambient air temp in a rack containing the amplifiers will not exceed a specified level and this is generally around 90-100 degrees max. The higher the temp the shorter the life span of the equipment will be.
In most cases...we air condition the room containing the amp racks and equipment. In one stadium system I did the equipment was in the sign in a special room made of insulated sections. These sections are the same material in which freezers are made of. The room large enough for 3 full size racks with room enough to pull equipment out of the racks and room to walk by the racks was cooled by a 5 ton air conditioner. This was for 55,000 watts of audio power. On a 100 degree day this was able to maintain a temperature of 82-85 degrees in the insulated room. So much for ambient air cooling....
Quote:
You can simply short circuit the ouptut of amp for playing if you dont have access to fire crackers safely because it will not turn up into smoke.
Maybe in your magic kingdom it won't. In the real world it can and does turn to s**t in a heart beat. You never short the output of any amplifier nor do you run a load heavier than what the amplifier is capable of handling.
Just my .02 based on real life experience
Hi from a pro-amp manufacturer
Hello Sir,
I dont know what type of amplifiers are you using or worked with.
I have never seen an pro amplifier which doesnt have short circuit , thermal, overcurrent,clip limiter protections in it.
I think you might be using a fancy gear [yamaha,peavy,inter-m,phonic]for your installations, thats why you are so much gentle with your gear.
Crown[ever seen their famous wrench crowbar short circuit demo], yorkville, Ecler, Stallion[our's own manufactured amp] are some of the highly reliable proven amps.
Professional amplifiers are the amps which remain safe in the event of short circuit, over-temp along and deliver continuous RMS around the clock.
Have you ever seen the Brazilian Carnival in which their are around 400 trucks equipped with atleast 35 amplifiers each [comprising 100000 per truck]and playing loud high pressure music 140dB in scorching heat with surrounding temp exceeding 45degree C., 99% humidity and amplifiers average working temp rise to about 75-80 degrees and that too in continuos mode 7 days and 24 hours a day.Nothing type of air conditioner is used.
There must be a misconception in your mind, thats why you are afraid and a little bit overcautious about over-temperature and short circuits.
something you ought to know better
regards,
kanwar
Hello Sir,
I dont know what type of amplifiers are you using or worked with.
I have never seen an pro amplifier which doesnt have short circuit , thermal, overcurrent,clip limiter protections in it.
I think you might be using a fancy gear [yamaha,peavy,inter-m,phonic]for your installations, thats why you are so much gentle with your gear.
Crown[ever seen their famous wrench crowbar short circuit demo], yorkville, Ecler, Stallion[our's own manufactured amp] are some of the highly reliable proven amps.
Professional amplifiers are the amps which remain safe in the event of short circuit, over-temp along and deliver continuous RMS around the clock.
Have you ever seen the Brazilian Carnival in which their are around 400 trucks equipped with atleast 35 amplifiers each [comprising 100000 per truck]and playing loud high pressure music 140dB in scorching heat with surrounding temp exceeding 45degree C., 99% humidity and amplifiers average working temp rise to about 75-80 degrees and that too in continuos mode 7 days and 24 hours a day.Nothing type of air conditioner is used.
There must be a misconception in your mind, thats why you are afraid and a little bit overcautious about over-temperature and short circuits.
something you ought to know better
regards,
kanwar
Quote:
I think you might be using a fancy gear [yamaha,peavy,inter-m,phonic]for your installations, thats why you are so much gentle with your gear.
Well, I don't consider these to be worthy of serious commercial applications. I will add Crown to the list also. I have used Crown in the past with less than desireable results.
One of the lines I favor is Crest.
Quote:
Have you ever seen the Brazilian Carnival in which their are around 400 trucks equipped with atleast 35 amplifiers each [comprising 100000 per truck]and playing loud high pressure music 140dB in scorching heat with surrounding temp exceeding 45degree C., 99% humidity and amplifiers average working temp rise to about 75-80 degrees and that too in continuos mode 7 days and 24 hours a day.Nothing type of air conditioner is used.
No, can't say I have ever seen a Brazilian circuis nor do I care to.
Quote:
here must be a misconception in your mind, thats why you are afraid and a little bit overcautious about over-temperature and short circuits.
something you ought to know better
Lets put it this way.... I put my reputation as well as my employers on the line every time I put together a system. We have to have something that will work when it is turned on and will stand up for years to come. This is why I don't put much faith in snake oil and lights.
There are countless studies that will back up the effects of overtemp and unnecessary stress on amps. You are welcome to your opinion as I am to mine but time always has a way of letting the truth come out. In short, my systems will be running with far less maintenance or failure than what yours will. nuff said.
I think you might be using a fancy gear [yamaha,peavy,inter-m,phonic]for your installations, thats why you are so much gentle with your gear.
Well, I don't consider these to be worthy of serious commercial applications. I will add Crown to the list also. I have used Crown in the past with less than desireable results.
One of the lines I favor is Crest.
Quote:
Have you ever seen the Brazilian Carnival in which their are around 400 trucks equipped with atleast 35 amplifiers each [comprising 100000 per truck]and playing loud high pressure music 140dB in scorching heat with surrounding temp exceeding 45degree C., 99% humidity and amplifiers average working temp rise to about 75-80 degrees and that too in continuos mode 7 days and 24 hours a day.Nothing type of air conditioner is used.
No, can't say I have ever seen a Brazilian circuis nor do I care to.
Quote:
here must be a misconception in your mind, thats why you are afraid and a little bit overcautious about over-temperature and short circuits.
something you ought to know better
Lets put it this way.... I put my reputation as well as my employers on the line every time I put together a system. We have to have something that will work when it is turned on and will stand up for years to come. This is why I don't put much faith in snake oil and lights.
There are countless studies that will back up the effects of overtemp and unnecessary stress on amps. You are welcome to your opinion as I am to mine but time always has a way of letting the truth come out. In short, my systems will be running with far less maintenance or failure than what yours will. nuff said.
kanwar,
I have to agree completely with burnedfingers. I've spent years repairing all brands of power amps. There are all made of the same parts and will obey the same exponential failure curve with temperature. All of them.
We have a party up here in Toronto called Carabanna. Yup, amps on trucks powered by gas generators in the hot sun. What a blast! Yeah, a continuous blast of dead amps. Killed by power surges and heat.
We have strip clubs that like to overheat entire racks of amps. They blow too. Even Brystons blow 'cause they are made with mortal parts like everyone else's. They like to tell people their amps don't blow. Right.
Please don't give the impression that pro amps are somehow made of special parts (yours included) that can't blow. Protection circuits are a last ditch effort to keep the magic smoke inside everything. The smoke sometimes comes out anyway. Like anything else, if you abuse these, they will blow too.
-Chris
I have to agree completely with burnedfingers. I've spent years repairing all brands of power amps. There are all made of the same parts and will obey the same exponential failure curve with temperature. All of them.
We have a party up here in Toronto called Carabanna. Yup, amps on trucks powered by gas generators in the hot sun. What a blast! Yeah, a continuous blast of dead amps. Killed by power surges and heat.
We have strip clubs that like to overheat entire racks of amps. They blow too. Even Brystons blow 'cause they are made with mortal parts like everyone else's. They like to tell people their amps don't blow. Right.
Please don't give the impression that pro amps are somehow made of special parts (yours included) that can't blow. Protection circuits are a last ditch effort to keep the magic smoke inside everything. The smoke sometimes comes out anyway. Like anything else, if you abuse these, they will blow too.
-Chris
reply
I got QSC RMX amps for doing for doing discos once a month.
And the protection circuits are great, thats just nonsense saying protection circuits don't work.
Well i've tested a short by putting two wires together. You heard an audible click on the relay when the short is applied and when taken off it clicks back. And a short circuit for a long time causes the circuit breaker at the back of amp to trip.
Got 1x QSC RMX4050HD for lows, 1x QSC RMX2450 for mids and 1x QSC RMX1450 for monitors ,1x QSC RMX850 for tweeters.
And my disco speakers are all P.Audio and Eminence loaded.
QSC RMX amps got the circuit breaker protection,relay protection,Triac Crowbar protection and last but not least the internal output and DC fuses. So impossible to blow up unless u tampered with the amp or spilt water in it.
Protected against, short, open circuits, mixmached loads,overheat, DC and overcurrent and undercurrent.
I got QSC RMX amps for doing for doing discos once a month.
And the protection circuits are great, thats just nonsense saying protection circuits don't work.
Well i've tested a short by putting two wires together. You heard an audible click on the relay when the short is applied and when taken off it clicks back. And a short circuit for a long time causes the circuit breaker at the back of amp to trip.
Got 1x QSC RMX4050HD for lows, 1x QSC RMX2450 for mids and 1x QSC RMX1450 for monitors ,1x QSC RMX850 for tweeters.
And my disco speakers are all P.Audio and Eminence loaded.
QSC RMX amps got the circuit breaker protection,relay protection,Triac Crowbar protection and last but not least the internal output and DC fuses. So impossible to blow up unless u tampered with the amp or spilt water in it.
Protected against, short, open circuits, mixmached loads,overheat, DC and overcurrent and undercurrent.
Wow! Am I missing something here? Since when is Disco considered serious audio?
Quote:
Well i've tested a short by putting two wires together. You heard an audible click on the relay when the short is applied and when taken off it clicks back. And a short circuit for a long time causes the circuit breaker at the back of amp to trip.
Well, you go ahead and keep shorting your two wires together and see what happens after a while.
Quote:
QSC RMX amps got the circuit breaker protection,relay protection,Triac Crowbar protection and last but not least the internal output and DC fuses. So impossible to blow up unless u tampered with the amp or spilt water in it.
Protected against, short, open circuits, mixmached loads,overheat, DC and overcurrent and undercurrent.
I am very familiar with Qsc amplifiers and many many others as far as that goes. Point is .... there is NO amplifier that can be relied upon Not to blow up. I serously doubt that you have the experience and knowledge to realize this. I don't care what brand it is or what is retailed for when it was new. They all blow up when abused and this includes the accidental shorting of the output stage.
Quote:
Well i've tested a short by putting two wires together. You heard an audible click on the relay when the short is applied and when taken off it clicks back. And a short circuit for a long time causes the circuit breaker at the back of amp to trip.
Well, you go ahead and keep shorting your two wires together and see what happens after a while.
Quote:
QSC RMX amps got the circuit breaker protection,relay protection,Triac Crowbar protection and last but not least the internal output and DC fuses. So impossible to blow up unless u tampered with the amp or spilt water in it.
Protected against, short, open circuits, mixmached loads,overheat, DC and overcurrent and undercurrent.
I am very familiar with Qsc amplifiers and many many others as far as that goes. Point is .... there is NO amplifier that can be relied upon Not to blow up. I serously doubt that you have the experience and knowledge to realize this. I don't care what brand it is or what is retailed for when it was new. They all blow up when abused and this includes the accidental shorting of the output stage.
So how did the QSC's blow up that I fixed ????
Oh, Madonna. That's it! They were Disco proof I guess.
I don't want to hear any more about indestructable amps that don't exist. Built from indestructable parts no one else can get.
The fact is that a protection circuit MAY save the amp this time. If they worked that well, many of us would be out of a job.
-Chris
Oh, Madonna. That's it! They were Disco proof I guess.
I don't want to hear any more about indestructable amps that don't exist. Built from indestructable parts no one else can get.
The fact is that a protection circuit MAY save the amp this time. If they worked that well, many of us would be out of a job.
-Chris
I think the point is that it not only de rigeur for PA amps to have all these defences but necessary given the unknown and often arduous conditions. Hi Fi amplifiers can throw out most protections in favour of finessed circuitry for better critical audio listening.
A PA amp with 0.1% THD is fine. But on a High End amp it could be a discordant harmonic or crosstalk, not OK!
A PA amp with 0.1% THD is fine. But on a High End amp it could be a discordant harmonic or crosstalk, not OK!
quote:
Hi Fi amplifiers can throw out most protections in favour of finessed circuitry for better critical audio listening.
Well, can you prove this with a schematic?
Quote:
A PA amp with 0.1% THD is fine. But on a High End amp it could be a discordant harmonic or crosstalk, not OK!
Again, please back up your statement with some facts.
Hi Fi amplifiers can throw out most protections in favour of finessed circuitry for better critical audio listening.
Well, can you prove this with a schematic?
Quote:
A PA amp with 0.1% THD is fine. But on a High End amp it could be a discordant harmonic or crosstalk, not OK!
Again, please back up your statement with some facts.
Hi everyone
Hi everyone,
Some insights regarding these BIPOLAR based PROAMPS.
QSC,PEAVEY,CROWN,CREST,etc all are the bipolar output amps.
These all implement FOLDBACK V-I LIMITING stage in which they sense the current through the emitter resistor of output device and the base-- emitter of driver stage is shunted by this action , which is good in theory, but practically it has a severe drawback because when a dead short is implemented at the output , this foldback limiter doesnt completely limits the output current and a little proportion of out put current still flows which inturns heatup the device and it lead to failure or less life.
Secondly, when you short an amplifier there are 2 reasons exist for its damage.
1. High voltage spiking is produced which exceeds the limit of VCE of transistor and it damages instantly.[this only happens when their is no load connected to the output, but you short the output]
Reverse baised diodes at output are often implemented but they doesnt exhibit a good approach and are not very fast to suppress the transients during dead short circuit.
2.High current starts to flow in the output which exceeds the device rating and it damages thereafter[this mostly happens , when the speaker gets shorted.]
Whereas we implement VERTICAL N-channel Mosfets at output stage which are robust than bipolars in terms of far superior SOA and non-existence of second breakdown voltage.
Our Protection doesnt include traditional VI based limiting, instead we use advanced muting , which upon activation completly mutes the input of amplifier which result in no signal at output that confers to no output power produced.
We donot use source resistors[emitter resistors in case of bipolars] to sense current, instead we use sensing of current in the supply rails.
When a speaker gets shorted[or a direct short], the output stage is confronted by overcurrent as well as very high energy transient spike voltages. to overcome this we have developed a unique method.
All the amplifiers feature output inductors with paralleled resistor at output of value usually 3-8uH and their usual diameter never exceeds 1 inch, but ours is a different case we employ a commonmode aircore inductor of 8uH with edgewound conductor featuring 3 inches of diameter which results in very High Q-factor, inturns yields excellent spike rejection when a dead short is implemented.This relieves the output mosfets from high energy kick back spikes and only overcurrent is faced which is then sensed accordingly and the input is muted, till the user resets it.
You can short circuit the output of our amp as long as you wish.
Some guys here would think this as a sort of advertisement or a challenge but its a simple generous approach implemented to save the output stage of amp.
Regarding overtemperature protection we implement:
32 Mosfets which confers for extra reserve to handle thermal stress efficiently.
Twin 5" 240VAC constant velocity cooling fans.
Oversized multi finned heatsinks.
input muting when heatsink temp. rises above 90Deg.C.
No power amp has ever used these types of simple hardware.
For overvoltage protection, we simply cut- off the mains supply by the traic crowbar.
regards to everyone ,
kanwar
Hi everyone,
Some insights regarding these BIPOLAR based PROAMPS.
QSC,PEAVEY,CROWN,CREST,etc all are the bipolar output amps.
These all implement FOLDBACK V-I LIMITING stage in which they sense the current through the emitter resistor of output device and the base-- emitter of driver stage is shunted by this action , which is good in theory, but practically it has a severe drawback because when a dead short is implemented at the output , this foldback limiter doesnt completely limits the output current and a little proportion of out put current still flows which inturns heatup the device and it lead to failure or less life.
Secondly, when you short an amplifier there are 2 reasons exist for its damage.
1. High voltage spiking is produced which exceeds the limit of VCE of transistor and it damages instantly.[this only happens when their is no load connected to the output, but you short the output]
Reverse baised diodes at output are often implemented but they doesnt exhibit a good approach and are not very fast to suppress the transients during dead short circuit.
2.High current starts to flow in the output which exceeds the device rating and it damages thereafter[this mostly happens , when the speaker gets shorted.]
Whereas we implement VERTICAL N-channel Mosfets at output stage which are robust than bipolars in terms of far superior SOA and non-existence of second breakdown voltage.
Our Protection doesnt include traditional VI based limiting, instead we use advanced muting , which upon activation completly mutes the input of amplifier which result in no signal at output that confers to no output power produced.
We donot use source resistors[emitter resistors in case of bipolars] to sense current, instead we use sensing of current in the supply rails.
When a speaker gets shorted[or a direct short], the output stage is confronted by overcurrent as well as very high energy transient spike voltages. to overcome this we have developed a unique method.
All the amplifiers feature output inductors with paralleled resistor at output of value usually 3-8uH and their usual diameter never exceeds 1 inch, but ours is a different case we employ a commonmode aircore inductor of 8uH with edgewound conductor featuring 3 inches of diameter which results in very High Q-factor, inturns yields excellent spike rejection when a dead short is implemented.This relieves the output mosfets from high energy kick back spikes and only overcurrent is faced which is then sensed accordingly and the input is muted, till the user resets it.
You can short circuit the output of our amp as long as you wish.
Some guys here would think this as a sort of advertisement or a challenge but its a simple generous approach implemented to save the output stage of amp.
Regarding overtemperature protection we implement:
32 Mosfets which confers for extra reserve to handle thermal stress efficiently.
Twin 5" 240VAC constant velocity cooling fans.
Oversized multi finned heatsinks.
input muting when heatsink temp. rises above 90Deg.C.
No power amp has ever used these types of simple hardware.
For overvoltage protection, we simply cut- off the mains supply by the traic crowbar.
regards to everyone ,
kanwar
kanwar
If audio consultants in this country(US.) viewed your circuit technology as being superior to what we are using now I'm sure we would be using it.
Personally, I see no advantage to using mosfets in a product that has to survive in a commercial application.
I suggest you pat yourself on the back and use your prior post for an advertising clip. Hopefully, the technology that you consider superior to our bipolar designs will stay in your country where it belongs.
If audio consultants in this country(US.) viewed your circuit technology as being superior to what we are using now I'm sure we would be using it.
Personally, I see no advantage to using mosfets in a product that has to survive in a commercial application.
I suggest you pat yourself on the back and use your prior post for an advertising clip. Hopefully, the technology that you consider superior to our bipolar designs will stay in your country where it belongs.
Burned Fingers -
It was purely an observation. If you don't agree I'm sure you can find an individual case or two to back you up. But I would much rather listen to a Quality Hi Fi amp with 80-100dB channel separation and 0.002% THD at 20KHz and comp FET front end than a workhorse with every protection possible, fans and 0.05% and 60dB or unstated crosstalk!
It's a nobrainer in your vernacular.
Then again if you can't hear the difference?
It was purely an observation. If you don't agree I'm sure you can find an individual case or two to back you up. But I would much rather listen to a Quality Hi Fi amp with 80-100dB channel separation and 0.002% THD at 20KHz and comp FET front end than a workhorse with every protection possible, fans and 0.05% and 60dB or unstated crosstalk!
It's a nobrainer in your vernacular.
Then again if you can't hear the difference?
Re: Hi everyone
Hi Kanwar,
What if you use 16 parallel bipolar transistors in the output? will this not give you a huge SOA for the total outputstage?
I did some calc with 5 parallel devises for my leach amp, and found that with 5 pairs it's safe to produce 300W+ into 8 ohms.
I'm still unsure about what's best for amplifiers, bipolar or mosfet?
BTW I use tons of power mosfets at work for switching power supply stuff, here I find them second to none.
\Jens
Workhorse said:
Hi Kanwar,
What if you use 16 parallel bipolar transistors in the output? will this not give you a huge SOA for the total outputstage?
I did some calc with 5 parallel devises for my leach amp, and found that with 5 pairs it's safe to produce 300W+ into 8 ohms.
I'm still unsure about what's best for amplifiers, bipolar or mosfet?
BTW I use tons of power mosfets at work for switching power supply stuff, here I find them second to none.
\Jens
Hi
Hi Jens,
Your question is good indeed, but my friend BJT's suffer from secondbreakdown voltage and at high temperature there is high risk of thermal runaway thats why these amp always have a attenuator protection with thermal overload.
In case of vertical mosfets they exhibit positive temp. coeff. at high drain currents therefore they prove to be more advantageous than BJT's.
Secondly , the transient response of Mosfets are far better than bipolars, especially at high drive signals.
Fabricating a amplifier for domestic use is much simple.
but when you fabricate a professional amplifier there are lot of responsibilites that are taken into considerations, therefore there is always a need of some extra safety to be implemented, because pro amps undergo much hardcore abuse than a home amp.
hi amplifier guru,
glad to see your comment.
guru , every pro-amp i have seen say Crown, Ecler all are short circuit protected and I have even tested them and also compared them to our amp. They use continuous averaging protection, but we employ latching mute which in case of short circuit latches the mute for indefinate time , till the user resets it.
Secondly our crosstalk seperation is 85dB.
Secondly domestic amps are meant for pleasurable listening at home, whereas pro-amps are meant for hi power public addressings in large gatherings with loud and clear sonic perspectives.
hi Burned fingers,
So you reflect the intellect of yourself indeed.
Thanks for the wonderful comments.
We really appreciate them, because we never take the things personally.Thats why we are professionals.
regards,
kanwar
JensRasmussen said:
Hi Jens,
Your question is good indeed, but my friend BJT's suffer from secondbreakdown voltage and at high temperature there is high risk of thermal runaway thats why these amp always have a attenuator protection with thermal overload.
In case of vertical mosfets they exhibit positive temp. coeff. at high drain currents therefore they prove to be more advantageous than BJT's.
Secondly , the transient response of Mosfets are far better than bipolars, especially at high drive signals.
Fabricating a amplifier for domestic use is much simple.
but when you fabricate a professional amplifier there are lot of responsibilites that are taken into considerations, therefore there is always a need of some extra safety to be implemented, because pro amps undergo much hardcore abuse than a home amp.
hi amplifier guru,
glad to see your comment.
guru , every pro-amp i have seen say Crown, Ecler all are short circuit protected and I have even tested them and also compared them to our amp. They use continuous averaging protection, but we employ latching mute which in case of short circuit latches the mute for indefinate time , till the user resets it.
Secondly our crosstalk seperation is 85dB.
Secondly domestic amps are meant for pleasurable listening at home, whereas pro-amps are meant for hi power public addressings in large gatherings with loud and clear sonic perspectives.
hi Burned fingers,
So you reflect the intellect of yourself indeed.
Thanks for the wonderful comments.
We really appreciate them, because we never take the things personally.Thats why we are professionals.
regards,
kanwar
- Status
- This old topic is closed. If you want to reopen this topic, contact a moderator using the "Report Post" button.