I will not tell yet where it came from. I got all the parts to duplicate it, and wondering what expert think of this kind of design. The power supply is +37 0 -37.
I got an original working amp made out of this sch (factory, not homemade) and all i can say is that it gives a lot of power for what it is.
Comments please !!
I got an original working amp made out of this sch (factory, not homemade) and all i can say is that it gives a lot of power for what it is.
Comments please !!
Attachments
Simple amplifier, uses cheap (and relatively dirty) 4558 opamp as driver. The next stage with Q101, 103 and Q102, 104 is a 10x amp to get the required voltage swing that the opamp is not able to deliver. The output stage is underbiased and will generate crossover distortion. Biasing is via D105...D107 and the bias voltage it makes (only 3 diodes) is too little to create the required idle current in the darlington output stage. Probably done to save an adjustment resistor and adjustment time. On the other hand it will also not drift.
Q113, 114 is for overload protection.
I guess it is a musical instrument amplifier or car audio amplifier in the category "most bang for the buck".
Steven
Q113, 114 is for overload protection.
I guess it is a musical instrument amplifier or car audio amplifier in the category "most bang for the buck".
Steven
Interesting comments. Yes, it is a car audio power amp, rated at an optimistic 250w max. It is bridgeable and can drive 2 ohm loads.
It is indeed a cheap amp, but delivers very high spl's on proper subwoofers.
My goal is to build such an amp to drive 2 TL for my home basement.
Maybe you have some suggestions to improve this design, i would like yo delete the op amps, and use some back to back fets or regulat transistors. I hate op amps
I also have a schematic from a Randal musical instrument amplifier, and is rated as much as 700w at 1ohm load. The circuit is incredibely simple and uses 2n3773 for the outputs. But the voltage rail is too high for now, i only have a toroidal transformer that can deliver 2x 30v ac.
The speakers i have for this project are 4 ohm car subwoofers that can take a lot.
thanks for the inputs.
Pat Allen
It is indeed a cheap amp, but delivers very high spl's on proper subwoofers.
My goal is to build such an amp to drive 2 TL for my home basement.
Maybe you have some suggestions to improve this design, i would like yo delete the op amps, and use some back to back fets or regulat transistors. I hate op amps
I also have a schematic from a Randal musical instrument amplifier, and is rated as much as 700w at 1ohm load. The circuit is incredibely simple and uses 2n3773 for the outputs. But the voltage rail is too high for now, i only have a toroidal transformer that can deliver 2x 30v ac.
The speakers i have for this project are 4 ohm car subwoofers that can take a lot.
thanks for the inputs.
Pat Allen
If you want to use these amplifiers and not start from scratch, I would just make very small changes on the original PCB, otherwise you could just as well start designing or building a completely different amplifier (even with the same components, well, at least the expensive components).
Replace the opamp with a better quality one and add a bias adjustment to the output stage by replacing the three series connected diodes by a Vbe multiplier, thermally coupled to the heatsink.
Changing the opamp may result in the necessity to change the frequency compensation (C114, C115), though. You will need a scope to check stability. The easiest is by applying a (small signal) square wave and looking at overshoots.
Steven
Replace the opamp with a better quality one and add a bias adjustment to the output stage by replacing the three series connected diodes by a Vbe multiplier, thermally coupled to the heatsink.
Changing the opamp may result in the necessity to change the frequency compensation (C114, C115), though. You will need a scope to check stability. The easiest is by applying a (small signal) square wave and looking at overshoots.
Steven
Hello Pat, are you hearing Charlie?...this one is Steve.
One of our big brains.
Just to inform, in the possibility you have not this information.
For me, low knowledge guy, everything this man say is a law...well .... each one is each one, you can be another big brain too.
regards,
Carlos
One of our big brains.
Just to inform, in the possibility you have not this information.
For me, low knowledge guy, everything this man say is a law...well .... each one is each one, you can be another big brain too.
regards,
Carlos
Yes, i see you respect him to, i will searching you, as you called and Steve appeared
So, as you have luck, i will be searching you, to have chance to hear what he say too.
regards,
Carlos
So, as you have luck, i will be searching you, to have chance to hear what he say too.
regards,
Carlos
Altec Lansing and EV use a more simplified version of this in their 9444B, (EV2600), 9446.(EV3200). The power output of the 9444 and 2600 is 200 WPC@8 ohms and 300 a channel at 4 ohms. The 9446 and 3200 put out 600 wpc at 8 ohms. I forgot the 4 ohm rating. The 9446 and 3200 will mono bridge at 1200 watts.
These can be purchased very cheaply on ebay with the going rate at about $100 an amp. I should note that these amps are commercial and will take a balanced or unbalanced input. They are also fan cooled and feature metal case T0-3 case outputs.
I think I could post a schematic since the original company went out of business. I think you would enjoy the simplicity of the design.
These can be purchased very cheaply on ebay with the going rate at about $100 an amp. I should note that these amps are commercial and will take a balanced or unbalanced input. They are also fan cooled and feature metal case T0-3 case outputs.
I think I could post a schematic since the original company went out of business. I think you would enjoy the simplicity of the design.
Inside a car, cabin gain boosts LF efficiency by 20 to 30dB. Mid frequencies are also boosted by 3 to 9dB due to corner gain or wall gain depending on driver placement. Also the cabin load effect at LF reduces the cone excursion requirements for a given SPL up to 1/10th in comparison with outdoors
So almost everything sounds loud inside a car [and manufacturers take good care of this fact
], but car audio gear produces frustrating results outside the car [sometimes also inside it...]
This amplifier only produces about 60W at 8 ohms with a standard unregulated supply. This power applied to a small 6" or 8" driver placed in a medium or large room is not going to sound loud at all, even TL loaded. With more power the cone excursion limit of the drivers will be easily reached. Typical 'Car-audio-loudness' is not so easy to obtain in rooms and it's quite hard outdoors...
So almost everything sounds loud inside a car [and manufacturers take good care of this fact
], but car audio gear produces frustrating results outside the car [sometimes also inside it...]This amplifier only produces about 60W at 8 ohms with a standard unregulated supply. This power applied to a small 6" or 8" driver placed in a medium or large room is not going to sound loud at all, even TL loaded. With more power the cone excursion limit of the drivers will be easily reached. Typical 'Car-audio-loudness' is not so easy to obtain in rooms and it's quite hard outdoors...
EVA has brought out some very good points here. Another point to consider is the power output of a car amplifier. I spent a lot of time on the bench in the 90's and one memory comes back to me when I think of car power amps. Even with a bank of batteries they don't deliver the advertized rating. My point is...why bother with the thought of designing or building a power amp when the models I have mentioned can be purchased for peanuts and sound good.
Have to know that i already use this exact same power amp outside of a car, in bridged mode with a 2 ohm load (two 4 ohm 10 inches subwoofers) and is sounds as loud in my listening room than in my car. So raw calculations gives
P=e2/r, (36v+36v, bridged mode)>2 /2ohm=2592w? rms=1832?
giving a 50% coeficient working number...916w?
I never got the way to calculate power output capability of a power amp...but i know ohm law !! 😀
Whats the thing with hearing Charlie? i dont get it at all.
For the Altec schematic, yes, show it !!!
thanks
Pat Allen
P=e2/r, (36v+36v, bridged mode)>2 /2ohm=2592w? rms=1832?
giving a 50% coeficient working number...916w?
I never got the way to calculate power output capability of a power amp...but i know ohm law !! 😀
Whats the thing with hearing Charlie? i dont get it at all.
For the Altec schematic, yes, show it !!!
thanks
Pat Allen
Pat
Put a sine wave into it and adjust till it clips then back off until clean. Have your dummy load connected on the output of the amp. Connect your RMS volt meter on the output or use your scope.
If you can produce 36volts out (which I doubt). 36X36=1296 divided by the resistance of the load(example 2 ohms)
1296 divided by 2 =648 watts. 4 ohm load 324 watts 8 ohm load = 162 watts.
Thinking it sounds just as loud is not proof. Measurements need to be taken and plotted. My opinion here.
Put a sine wave into it and adjust till it clips then back off until clean. Have your dummy load connected on the output of the amp. Connect your RMS volt meter on the output or use your scope.
If you can produce 36volts out (which I doubt). 36X36=1296 divided by the resistance of the load(example 2 ohms)
1296 divided by 2 =648 watts. 4 ohm load 324 watts 8 ohm load = 162 watts.
Thinking it sounds just as loud is not proof. Measurements need to be taken and plotted. My opinion here.
Oh well, by the way, i dont want to reinvent the wheel, i just want to know if the amp i already have can be upgraded. I am a poor man, i just bought a house...🙄
I have all the parts to build another one and maybe run 2 in bridged mode...
If i could find a better schematic to use my irfp250r, i will surely build something else. Main problem is my power supply wich can only deliver around +40 0 -40v at around 8 amps, loaded with 8x 34800uf sangamo caps.
And i know for sure that most of the amp never gives the advertised numbers, but one company that i have worked for showed very realistic numbers, Alpine power amps always felt on tap with theirs power ratings...i remember one of the last series build wich was a 1000 series if memory ok, the power supply was something like +85 0 -85 on 4 ohm loads, and it was stable until cliping. that gaves then 136db spl's with a RTA with 2 12 inches subs in a demo caravan.
I was Alpine authorized service center in the past.
thanks
Pat Allen
I have all the parts to build another one and maybe run 2 in bridged mode...
If i could find a better schematic to use my irfp250r, i will surely build something else. Main problem is my power supply wich can only deliver around +40 0 -40v at around 8 amps, loaded with 8x 34800uf sangamo caps.
And i know for sure that most of the amp never gives the advertised numbers, but one company that i have worked for showed very realistic numbers, Alpine power amps always felt on tap with theirs power ratings...i remember one of the last series build wich was a 1000 series if memory ok, the power supply was something like +85 0 -85 on 4 ohm loads, and it was stable until cliping. that gaves then 136db spl's with a RTA with 2 12 inches subs in a demo caravan.
I was Alpine authorized service center in the past.
thanks
Pat Allen
burnedfingers said:
I use it in bridged mode...wich is then 36+36 volts=72. I never measure this amp on a bench, i got all the instruments to do so.
If the sounds that goes thru my ears feels as loud as i wish, then i am satisfied, and it is.
Pat Allen
Quote:
I use it in bridged mode...wich is then 36+36 volts=72. What is 72 volts? The ouput to the load? Please explain.
Schematic of 9444
I use it in bridged mode...wich is then 36+36 volts=72. What is 72 volts? The ouput to the load? Please explain.
Schematic of 9444
well, my understanding of a bridged mode power amp with rail to rail power supply is that you apply then the sum of the rail to rail voltage?
It is powered by a +36v 0 -36 volts power supply, so when bridged, the voltage capable to be sent to the sepaker is the full vcc swing and is then 72 volts, if, of course, the power supply can handle it.
The load is 2 ohm, 2x4 0hm speakers in parralel.
Pat Allen
It is powered by a +36v 0 -36 volts power supply, so when bridged, the voltage capable to be sent to the sepaker is the full vcc swing and is then 72 volts, if, of course, the power supply can handle it.
The load is 2 ohm, 2x4 0hm speakers in parralel.
Pat Allen
Pat
Example:
Altec 9444 has a B+ and B- voltage of 77V. That does not mean you will see a power output of 154 volts. It is capable of running 200 watts @ 8ohms and 300 watts per channel at 4 ohms or 600
watts mono bridge mode. There are a lot of factors to consider. I could ramble on her for several pages at least making sense of it all. To sum it all up. Only clear way to tell output is to test. Roughly calculated in mono bridge mode power output is less than 4 times the normal rating in watts. The power supply and the design of the amplifier has a bearing on the output capabilities. In the case of this amp it puts out roughly 70 volts into an 8 ohm load at clipping.
The 9446 or 3200 will put out in excess of its rating into an 8 ohm load. It is rated at 1200 watts mono bridge and puts out 1250-1300 watts.
Note* Its rail is plus and minus 91 volts. It puts out about 100V RMS into an 8 ohm dummy load. I have very large fan cooled dummy loads.
Example:
Altec 9444 has a B+ and B- voltage of 77V. That does not mean you will see a power output of 154 volts. It is capable of running 200 watts @ 8ohms and 300 watts per channel at 4 ohms or 600
watts mono bridge mode. There are a lot of factors to consider. I could ramble on her for several pages at least making sense of it all. To sum it all up. Only clear way to tell output is to test. Roughly calculated in mono bridge mode power output is less than 4 times the normal rating in watts. The power supply and the design of the amplifier has a bearing on the output capabilities. In the case of this amp it puts out roughly 70 volts into an 8 ohm load at clipping.
The 9446 or 3200 will put out in excess of its rating into an 8 ohm load. It is rated at 1200 watts mono bridge and puts out 1250-1300 watts.
Note* Its rail is plus and minus 91 volts. It puts out about 100V RMS into an 8 ohm dummy load. I have very large fan cooled dummy loads.
well, i know physicaly how bridging an amp work for sure, you seems to under estimate my knowledge in this path, the final result and goal is to have more voltage swing at the speaker, by dephasing one of the chanel 180deg. and applying the same source to the amps, so when on channel swing at its +vcc, the other swing at its -vcc. Connecting the speaker at both channel outputs finishes the bridging mode. It should then send the (72v) to the speaker, unles that, it is useless to have a bridging operation if it dont goes thru, surely the power supply have to handle all this.
The amp i got specifically got this feature and believe it or not, it does send the full vcc swing to the speaker.
This is how bridging works and it is used specificaly in audio mobile where most of the decks have btl mode power amps, wich can deliver then more than 30w with only 12v of vcc.
Pat Allen
The amp i got specifically got this feature and believe it or not, it does send the full vcc swing to the speaker.
This is how bridging works and it is used specificaly in audio mobile where most of the decks have btl mode power amps, wich can deliver then more than 30w with only 12v of vcc.
Pat Allen
Mr. Moderator
I sent a schematic of a 9444 Altec amplifier not of current production as Altec Lansing (original company went out of business). This schematic is not proprietary information and can be disclosed without any written permission.
The schematic I fear has gone into the Twlight Zone and is not appearing.
I sent a schematic of a 9444 Altec amplifier not of current production as Altec Lansing (original company went out of business). This schematic is not proprietary information and can be disclosed without any written permission.
The schematic I fear has gone into the Twlight Zone and is not appearing.
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