thylantyr said:In SPL contests they do indeed play sine waves but just long enough to get an SPL reading.
/true
But the owner of the vehicle will still be playing his tones all day
long to aggrevate people with this sound system and perhaps
blowing up his woofers and amplifiers that are not worthly. /heh
Car audio is an abusive environment and amplfiers that are
not designed to be robust will get a bad reputation, so it's
in their best interest to make it beefy.
Digressing here gain but IMHO PPI amps ROCK!
Commentable Thoughts
I Fairly agree with Dan Fraser for his Trafo details.
But there is a little bit he is missing ,as in our case we use mosfets at output and all our Professional amps are pre-Bridged[4 amps to give 2 stereo bridge amps], for 1600Wrms rating we use 1200VA transformer. When an amp is running in bridge mode its output is dependent on +VCC and -VCC rails only, Ground or center tap does'nt counts thats why efficiency is high and lossess are low and output his quadrupled fairly.
With Regards
AmPmAn
I Fairly agree with Dan Fraser for his Trafo details.
But there is a little bit he is missing ,as in our case we use mosfets at output and all our Professional amps are pre-Bridged[4 amps to give 2 stereo bridge amps], for 1600Wrms rating we use 1200VA transformer. When an amp is running in bridge mode its output is dependent on +VCC and -VCC rails only, Ground or center tap does'nt counts thats why efficiency is high and lossess are low and output his quadrupled fairly.
With Regards
AmPmAn
Dear AmPmAn , Mr Dan Fraser has clearly said that he is using very large caps
in his amps , like this it is possible to reduce the transformer VA and also the
weight of the amp , hence his statement bears weight that a 925 VA transformer
can power a 2000W amp. I do not think this theory will make any differance in
bridge amps ,it is the power that matters.
in his amps , like this it is possible to reduce the transformer VA and also the
weight of the amp , hence his statement bears weight that a 925 VA transformer
can power a 2000W amp. I do not think this theory will make any differance in
bridge amps ,it is the power that matters.
K-amps said:
Question about this. Should you be choosing values of capacitance based on wattage, or output current? Energy stored by a capacitor is E = 1/2 * C * V^2, so if you're running an amp into an 8 ohm load with 35V rails the caps would hold 2.88 Joules. If you're running the same 8 ohm load with 50V rails, you might get twice the output power, but the higher rail voltage would also give you 5.88 Joules.
I'm not really sure on that though. Maybe an expert could pitch in, but otherwise if you wanted 1000W you'd need not only 100uF of capacitance, but at 100V. That would get expensive.
Capacitors
My LF amp is a 1000W classD amp operating with sa single 110V DC supply. On this I use 4 x 2700uFd 160V capacitors in parallel. Why? Because I cannot get a 10,000uFd at 120V capacitor. This may seem thin to you for capacitor size.
However, since energy storage goes up by linearly with capacitance but by the square of the voltage in the capacitor, the amount of energy I have stored is quite massive. As well, we have size constraints limiting the maximum volume available for cramming in capacitors.
As well, the parallel arrangement makes the effective series resistance of the capacitors much smaller, allowing for more efficient of dumping of power into the load.
My LF amp is a 1000W classD amp operating with sa single 110V DC supply. On this I use 4 x 2700uFd 160V capacitors in parallel. Why? Because I cannot get a 10,000uFd at 120V capacitor. This may seem thin to you for capacitor size.
However, since energy storage goes up by linearly with capacitance but by the square of the voltage in the capacitor, the amount of energy I have stored is quite massive. As well, we have size constraints limiting the maximum volume available for cramming in capacitors.
As well, the parallel arrangement makes the effective series resistance of the capacitors much smaller, allowing for more efficient of dumping of power into the load.
Commentable Thoughts
Hi Fraser,
Our Linear as well as class- D amp uses 3 X 10000MFD/63V caps per rail in dual supply configuration , therefore i can fairly substitute 1000VA trafo for 1600WRMS amp.
Dear Rajeev,
When a linear amp is working in bridge mode thier is more stress on power supply due to continous current consumption from both the supply rails simuntaneously.
With Regards,
ampmAn
Hi Fraser,
Our Linear as well as class- D amp uses 3 X 10000MFD/63V caps per rail in dual supply configuration , therefore i can fairly substitute 1000VA trafo for 1600WRMS amp.
Dear Rajeev,
When a linear amp is working in bridge mode thier is more stress on power supply due to continous current consumption from both the supply rails simuntaneously.
With Regards,
ampmAn
Bridge Mode
Actually, bridge mode is no harder on a transformer than regular mode. The transformer only cares how many watts you pull through through it averaged over a period determined by its mass. There is quite a thermal lag. Besides, the signal is usually quite a bit higher in frequency that the capacitor refresh rate so that no matter whether the amp is in bridge mode or not, the caps end up sucking power through the transformer every half cycle anyway.
The power supply tops up the caps every half cucle of the AC line no matter what. The people who think bridge mode is harder on an amp are thinking only of times when the signal is at a frequency of 1/2 the capacitor refresh rate (100 or 120Hz) or lower.
In reality, if you are developing 1000W or audio from an unbridged amplifier or 1000W in a bridged amp, when it comes to the transformer rating, watts is watts. The same deratings apply.
Yes, when you bridge an amplifier, you can get more power into a given load but you don't get something for nothing. An amplifier that can develop 1000W per channel into a 4 ohm load, will develop 2000W into an 8 ohm load. However, the total power demand is the same.
If you run the amp bridged into a 4 ohm load, each channel "sees" an effective 2 ohm load and yes, you are doubling the power demand. But this is not the slightest bit different than running each channel into a 2 ohm load.
Proper bridging application of power amplifiers makes no difference to the calculations people like me, who design amplifiers for a living, use to size transformers. Believe me, there is no plot to cheat the user on transformer size. Actually, in the pro field, we are constant pressure to ensure there are as few warranty claims as possible and undersizing a transformer is false economy. Besides, CSA, UL, VDE and the rest of the safety agencies would roast us alive if we skimped on the power transformer.
Actually, bridge mode is no harder on a transformer than regular mode. The transformer only cares how many watts you pull through through it averaged over a period determined by its mass. There is quite a thermal lag. Besides, the signal is usually quite a bit higher in frequency that the capacitor refresh rate so that no matter whether the amp is in bridge mode or not, the caps end up sucking power through the transformer every half cycle anyway.
The power supply tops up the caps every half cucle of the AC line no matter what. The people who think bridge mode is harder on an amp are thinking only of times when the signal is at a frequency of 1/2 the capacitor refresh rate (100 or 120Hz) or lower.
In reality, if you are developing 1000W or audio from an unbridged amplifier or 1000W in a bridged amp, when it comes to the transformer rating, watts is watts. The same deratings apply.
Yes, when you bridge an amplifier, you can get more power into a given load but you don't get something for nothing. An amplifier that can develop 1000W per channel into a 4 ohm load, will develop 2000W into an 8 ohm load. However, the total power demand is the same.
If you run the amp bridged into a 4 ohm load, each channel "sees" an effective 2 ohm load and yes, you are doubling the power demand. But this is not the slightest bit different than running each channel into a 2 ohm load.
Proper bridging application of power amplifiers makes no difference to the calculations people like me, who design amplifiers for a living, use to size transformers. Believe me, there is no plot to cheat the user on transformer size. Actually, in the pro field, we are constant pressure to ensure there are as few warranty claims as possible and undersizing a transformer is false economy. Besides, CSA, UL, VDE and the rest of the safety agencies would roast us alive if we skimped on the power transformer.
Re: Bridge Mode
Hi Fraser,
In Subwoofer Application the signal frequency can be as low as 18 to 30 HertZ down , This is the situation where Trafo needs attention in Bridge mode.
Friend DAN FRASER PLZ note We also manufacture professional Mosfet /IGBT amps for our livlihood and to quench our thirst for creation of amplifiers[but it is going on and on increasing with the passage of time].
YES ur rite on safety agencies that one cant skimp on power trafo, but there is a logicable way to ensure that every aspect of power amplification must be considered accordingly, which in my opinion ur r on RITE track buddy.
Happy Amping,
Kanwar Abhishek
dmfraser said:
Hi Fraser,
In Subwoofer Application the signal frequency can be as low as 18 to 30 HertZ down , This is the situation where Trafo needs attention in Bridge mode.
dmfraser said:
Friend DAN FRASER PLZ note We also manufacture professional Mosfet /IGBT amps for our livlihood and to quench our thirst for creation of amplifiers[but it is going on and on increasing with the passage of time].
YES ur rite on safety agencies that one cant skimp on power trafo, but there is a logicable way to ensure that every aspect of power amplification must be considered accordingly, which in my opinion ur r on RITE track buddy.
Happy Amping,
Kanwar Abhishek
Hello Ampman,
lets take an example,
suppose there are two identical power amps powered by the same powersupply ,
they deliver 300w each at 4ohms,total output of both amps = 600w .
now if these two power amps are connected in bridge mode and deliver 600w at
8ohms
You say that the transformer VA requirement in the bridge mode will be more , in
both cases the power output is 600w, (I understand that in bridge mode the
current will be flowing between +vcc & -vcc as you said )
Please could you explain further
lets take an example,
suppose there are two identical power amps powered by the same powersupply ,
they deliver 300w each at 4ohms,total output of both amps = 600w .
now if these two power amps are connected in bridge mode and deliver 600w at
8ohms
You say that the transformer VA requirement in the bridge mode will be more , in
both cases the power output is 600w, (I understand that in bridge mode the
current will be flowing between +vcc & -vcc as you said )
Please could you explain further
Commentable Thoughts
At normal frequency the power requirement is same but at subsonic frequency signal i.e. 18HZ then the caps charging plays the important role because in india line supply is at 50Hz the charging of caps takes place every half cycle with frequency of 100Hz . Therefore subsonic requirements stress the trafo if amp is operated in bridge mode, it sucks the current from both rails and charging lags behind.
Regards
Ampman
At normal frequency the power requirement is same but at subsonic frequency signal i.e. 18HZ then the caps charging plays the important role because in india line supply is at 50Hz the charging of caps takes place every half cycle with frequency of 100Hz . Therefore subsonic requirements stress the trafo if amp is operated in bridge mode, it sucks the current from both rails and charging lags behind.
Regards
Ampman
hi
quite interesting - I thought we had - had this discussion with Yuri Gustaz of PSS Audio (France) trying to defend why he underpowers the transformers so miserably
I yet like the power supply rated 1.5 times the load presented to it with atleast 60,000 micro farads / per rail
plus bifiliar winding at both end dual caps - bus rails etc
(when i have the set up i will post the pics of the amps i have made in this respect)
this view is sitrictly for pro audio - as this is where i have done most of my measurements
i have measured 28 amps continous current demand by a well loaded Heavily modified dual JBL 2242 drivers to a peak of 128 amps
this was easily supplied with Crest Pro 8000 - in bridge mode - 2800 W
if the amp had clipped at that level - the speakers would have certainly found their way to my work shop
weaker players in pro audio are extensivly using out - put current limiting - therefore further reducing the potential of a customer discovering the potential of the latest
1000 W Rms or 800 W from EV , JBL and RCF
therefore I awe Meyer sound their drivers are very good and they over power them well - and only sell powered speaker units
suranjan
transducer design engineer
quite interesting - I thought we had - had this discussion with Yuri Gustaz of PSS Audio (France) trying to defend why he underpowers the transformers so miserably
I yet like the power supply rated 1.5 times the load presented to it with atleast 60,000 micro farads / per rail
plus bifiliar winding at both end dual caps - bus rails etc
(when i have the set up i will post the pics of the amps i have made in this respect)
this view is sitrictly for pro audio - as this is where i have done most of my measurements
i have measured 28 amps continous current demand by a well loaded Heavily modified dual JBL 2242 drivers to a peak of 128 amps
this was easily supplied with Crest Pro 8000 - in bridge mode - 2800 W
if the amp had clipped at that level - the speakers would have certainly found their way to my work shop
weaker players in pro audio are extensivly using out - put current limiting - therefore further reducing the potential of a customer discovering the potential of the latest
1000 W Rms or 800 W from EV , JBL and RCF
therefore I awe Meyer sound their drivers are very good and they over power them well - and only sell powered speaker units
suranjan
transducer design engineer
Dear Ampman
lets be more practical , normally we do not go as low as 18hz , nor do I think there are professional loudspeakers / subwoofers capable of handeling 500- 1000 watts at 18hz , then why do we need the extra transformer capacity for the frequences at which the amp is not being used ,
lets be more practical , normally we do not go as low as 18hz , nor do I think there are professional loudspeakers / subwoofers capable of handeling 500- 1000 watts at 18hz , then why do we need the extra transformer capacity for the frequences at which the amp is not being used ,
hi
rajeev
we feed amps square waves , noise and triangle waves at full power
if we do this to speakers - u will soon get a funny burning smell from them
the speaker current demand cannot be predicted easily
since we are talking about pro audio - a jbl 2226 has been used in horn loaded cabinets - reverse loaded , w bins , front firing , compact enclosures the works
the driver is designed to be very versatile to be used in all sorts of application
we used it in a dual push - pull very large enclosure / ported
- one driver front facing on the baffle and the other reverse facing on the baffle
(it is an eaw design - only the rcf drivers in the eaw were a bit flimsy therefore we used 2226)
first of all this was designed to push below 60 hz as above that we had meyer sound dual 15 inch 2800 w rms powered units
the current drawn by the jbl were amazing much more than we had ever measured them drawing - when compaired to other applicatons
as speakers are electro - mechanical devices
one cannot predict the type of peak mechanical load on a driver - and hence the peak eletrical demand of the driver to operate in that load condition
one cannot go by the electrical condition alone when trying to judge load on amps from a drive unit (ie. 600 w rms at a running range of 32 hz to 120 hz etc ) - u never know when it may go to subsonics - speacially with the sychedellic music being pushed to limits
suranjan das gupta
transducer design engineer
rajeev
we feed amps square waves , noise and triangle waves at full power
if we do this to speakers - u will soon get a funny burning smell from them
the speaker current demand cannot be predicted easily
since we are talking about pro audio - a jbl 2226 has been used in horn loaded cabinets - reverse loaded , w bins , front firing , compact enclosures the works
the driver is designed to be very versatile to be used in all sorts of application
we used it in a dual push - pull very large enclosure / ported
- one driver front facing on the baffle and the other reverse facing on the baffle
(it is an eaw design - only the rcf drivers in the eaw were a bit flimsy therefore we used 2226)
first of all this was designed to push below 60 hz as above that we had meyer sound dual 15 inch 2800 w rms powered units
the current drawn by the jbl were amazing much more than we had ever measured them drawing - when compaired to other applicatons
as speakers are electro - mechanical devices
one cannot predict the type of peak mechanical load on a driver - and hence the peak eletrical demand of the driver to operate in that load condition
one cannot go by the electrical condition alone when trying to judge load on amps from a drive unit (ie. 600 w rms at a running range of 32 hz to 120 hz etc ) - u never know when it may go to subsonics - speacially with the sychedellic music being pushed to limits
suranjan das gupta
transducer design engineer
Belles 450 power amp
I'm using, right now, literally.... a modified Belles 450 power amp. this is the amplifier ..I very very much suspect, that Dave Belles is using as the basis for his current run of amplfiers.
The Belles 450, in stock form, a 1500VA rated Torid transformer. The way it is wired, is as a pair of 750VA Trans with their input and outputs running parallel. This means the inductance or in this case, transient current delivery is noticably less of an issue. A single 750, so to speak. I've been toying with the idea of separating the two trannies and running dual mono. 1 rectifier, a bit of wring and board changes and I'm fully dual mono in the one chassis..except for the signal of one channel modulating the parallaled tranny for the other channel....
He placed 40kuf in the unit, at 10kuf per voltage rail per channel. I upped that to approximately 80kuf per rail. The unit now has over 300kuf or 0.3 Farad of energy storage. Yes, the lights go dim when the unit is turned on!
And, trust me..there IS a benefit to going to such extreme levels of capacitance and Trannny VA ratings. BIG TIME. If you want something that is thoroughly pleasant to listen to -specifically- as your tastes in audio equipment get bettter..and better..and better.... then.. put down the engineering rags and textbooks. Instead... rely on your ears, for they are much more of an arbiter of reality than any book filled with 'theories'. (if you have the lack of linearity in your thinking to make the jumps required. A big 'if' for some of you, and please don't come after me about that..as it is your issue...not mine...)
I'm using, right now, literally.... a modified Belles 450 power amp. this is the amplifier ..I very very much suspect, that Dave Belles is using as the basis for his current run of amplfiers.
The Belles 450, in stock form, a 1500VA rated Torid transformer. The way it is wired, is as a pair of 750VA Trans with their input and outputs running parallel. This means the inductance or in this case, transient current delivery is noticably less of an issue. A single 750, so to speak. I've been toying with the idea of separating the two trannies and running dual mono. 1 rectifier, a bit of wring and board changes and I'm fully dual mono in the one chassis..except for the signal of one channel modulating the parallaled tranny for the other channel....
He placed 40kuf in the unit, at 10kuf per voltage rail per channel. I upped that to approximately 80kuf per rail. The unit now has over 300kuf or 0.3 Farad of energy storage. Yes, the lights go dim when the unit is turned on!
And, trust me..there IS a benefit to going to such extreme levels of capacitance and Trannny VA ratings. BIG TIME. If you want something that is thoroughly pleasant to listen to -specifically- as your tastes in audio equipment get bettter..and better..and better.... then.. put down the engineering rags and textbooks. Instead... rely on your ears, for they are much more of an arbiter of reality than any book filled with 'theories'. (if you have the lack of linearity in your thinking to make the jumps required. A big 'if' for some of you, and please don't come after me about that..as it is your issue...not mine...)
Suranjan ,
You and ampman seem to be doing a good job,at subsonics be careful that your buildings are strong enough or both of you will make news.
KBK
I wish I was there with you in the wilds of Canada,most beautiful at this time of the year,some beer and the taste of your matured sound system , aaahhhh what a thought.......
Yes you are right, if we overrate the transformer and capacitors both , to the extend like YOU have done IT WILL MAKE LOTS OF DIFFERANCE
You and ampman seem to be doing a good job,at subsonics be careful that your buildings are strong enough or both of you will make news.
KBK
I wish I was there with you in the wilds of Canada,most beautiful at this time of the year,some beer and the taste of your matured sound system , aaahhhh what a thought.......
Yes you are right, if we overrate the transformer and capacitors both , to the extend like YOU have done IT WILL MAKE LOTS OF DIFFERANCE
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