excuse megtforme00 said:
i was building this amp but i dont have the pcb design so i search and i found this thread so i can i request?
Can you please send me the sch. and brd file/format (express Pcb or etc.) of this amp thanks. I cant pm anybody cause im newbie in this forum
sorry for my BAD english im from the philippines
jayke
The baby Qausi amp NMOS 200
(power amp under development) is a
good one to try. He has the layouts on his site..
http://www.adam.com.au/cgpap/QuasiWeb/index.htm
I have built 3 of these and they are
will run on 30-0-30 (60w),too .
Easy, simple, modeled after "blameless" amp(.008%dist).
(power amp under development) is a
good one to try. He has the layouts on his site..
http://www.adam.com.au/cgpap/QuasiWeb/index.htm
I have built 3 of these and they are
will run on 30-0-30 (60w),too .
Easy, simple, modeled after "blameless" amp(.008%dist).
Frustrated and disappointment
I had constructed the circuit: 100 to 150 Watt Amp coined by Jon Tirone and with no prevailed. It had come to my disappointment by reading some of the postings by claiming that the circuits itself won’t work due to faulty designed. I could not believe of what I had heard, but it seems to be true that the circuit wasn’t worked at all. I had tried my best in constructing that projects which included redrawn the circuit schematic, PCB’s layout, affords, money and even time. Perhaps the most important was my dream of having constructing 2 channels of 300Watts of amplifier (based on the original circuit design) and incorporate it with my own guitar amp. I had worked through the circuit in details, inch by inch over and over again just to make sure there are no flows in constructing the PCB layout. Even to the details of thermology with even much better heat sink mounted to the Output Transistors. Upon switching on the amplifier, the Darlington pair transistor TIP147 became hot and that went on with the cement resistor 0.33ohm. It produced a humming sound when switched on and stay on that way until switch off.
I had constructed the circuit: 100 to 150 Watt Amp coined by Jon Tirone and with no prevailed. It had come to my disappointment by reading some of the postings by claiming that the circuits itself won’t work due to faulty designed. I could not believe of what I had heard, but it seems to be true that the circuit wasn’t worked at all. I had tried my best in constructing that projects which included redrawn the circuit schematic, PCB’s layout, affords, money and even time. Perhaps the most important was my dream of having constructing 2 channels of 300Watts of amplifier (based on the original circuit design) and incorporate it with my own guitar amp. I had worked through the circuit in details, inch by inch over and over again just to make sure there are no flows in constructing the PCB layout. Even to the details of thermology with even much better heat sink mounted to the Output Transistors. Upon switching on the amplifier, the Darlington pair transistor TIP147 became hot and that went on with the cement resistor 0.33ohm. It produced a humming sound when switched on and stay on that way until switch off.
This amp works! I have pictures...
Poor Mr. Tirone, AKA Mr. Fisher, has taken quite a beating in this thread. It's undeserved. I know it's been a while since anyone posted here, but I'd like to clear the air.
Here's my motivation... I stumbled on a blown up Rogue powered PA head. The output stage was fried. I fixed it and sold it. The output signal looked pretty bad, but I sold it cheap. Well, it didn't take long but the thing blew up again. I suspect the new owner shorted the speaker cable. He brought it back with a 30 Amp fuse in the mains. The thermal fuse buried in the transformer was blown as was the power output board. I felt bad for the guy and told him I'd fix it.
So I really didn't want to fix the output board again because it was fried to a crisp. Here's what it looked like:
Searching the internet, I stumbled on Mr. Fisher's design like so many others have done. Off I went to build the cheapest 150W amp of all time -- didn't find this thread until after I was done. Built the amp on a Radio Shack proto board. Here's what it looks like:
Not much to it. Only mod I made was to use 3 biasing diodes instead of 2, but it works either way. Has a little cross-over distortion with 2, though. So I first powered it up with +/-18V rails and drove a 1kHz signal into an 8-Ohm speaker load. Here's what I got:
As you can see from the above picture, clipping occurs at 15.3 Watts. My supply rails dropped to +/-17.15V. (Scope is set to 5V/div.) Next, I hooked it up to a 4-Ohm resistive dummy load. Here's what I got:
24.5 Watts into 4-Ohms. Not bad... Feeling confident, I plugged this cheap amp into the Rogue PA's +/-49.5V supply. Starting with the 8-Ohm speaker, I got this:
Scope is now set to 10V/div, and that's a pretty clean 103 Watts we're seeing. Plugging in the dummy load yields 128.8 Watts into 4-Ohms. It could probably do more, but that's all my supply can source. Here's the picture:
In all of these pictures, the voltmeter shows the (close to RMS) voltage across the output.
So Mr. Fisher's amp works. Earlier in this thread, Gaetan8888 posted a link to another amp design that didn't get much criticism. I repeat it here:
http://www.elecfree.com/circuit/powe...3055-with-pcb/
Notice that these designs are nearly identical except that Mr. Fisher's design uses darlingtons to eliminate some more parts. It also uses 3 bias diodes as I did. Here's why. When using only 2 diodes, a slight amount of crossover distortion can be seen at low signal levels. Here's the picture:
It's small and hard to see, but it's there. Here it is with 3 diodes:
My biggest concern with this amp is that it does not have short-circuit protection. It will fry the output transistors in an instant if you short the output -- even at low signal levels. I think it would be worth the added cost of 2 small transistors, 2 diodes and 4 resistors. These extra parts go for pennies. Instead what I did was to put a fuse in line with the speaker out. Don't worry, I won't put a 15A fuse in it. It will be a 7A fast-blow.
I see no stability problems with this amp. It works fine. It doesn't squeal and it doesn't smoke. All of my tests were on the bench. I'll be using it for some program material soon and will post my results. Here's what the finished repair looks like:
I don't have a distortion meter so I can't tell you how it's fidelity is, but my guess is that it's not too terribly bad. It's definitely not audiophile gear, but it's not total lo-fi either.
If you built it and it doesn't work, you did something wrong because I am convinced, this design works.
Poor Mr. Tirone, AKA Mr. Fisher, has taken quite a beating in this thread. It's undeserved. I know it's been a while since anyone posted here, but I'd like to clear the air.
Here's my motivation... I stumbled on a blown up Rogue powered PA head. The output stage was fried. I fixed it and sold it. The output signal looked pretty bad, but I sold it cheap. Well, it didn't take long but the thing blew up again. I suspect the new owner shorted the speaker cable. He brought it back with a 30 Amp fuse in the mains. The thermal fuse buried in the transformer was blown as was the power output board. I felt bad for the guy and told him I'd fix it.
So I really didn't want to fix the output board again because it was fried to a crisp. Here's what it looked like:
An externally hosted image should be here but it was not working when we last tested it.
An externally hosted image should be here but it was not working when we last tested it.
An externally hosted image should be here but it was not working when we last tested it.
An externally hosted image should be here but it was not working when we last tested it.
Searching the internet, I stumbled on Mr. Fisher's design like so many others have done. Off I went to build the cheapest 150W amp of all time -- didn't find this thread until after I was done. Built the amp on a Radio Shack proto board. Here's what it looks like:
An externally hosted image should be here but it was not working when we last tested it.
An externally hosted image should be here but it was not working when we last tested it.
An externally hosted image should be here but it was not working when we last tested it.
Not much to it. Only mod I made was to use 3 biasing diodes instead of 2, but it works either way. Has a little cross-over distortion with 2, though. So I first powered it up with +/-18V rails and drove a 1kHz signal into an 8-Ohm speaker load. Here's what I got:
An externally hosted image should be here but it was not working when we last tested it.
As you can see from the above picture, clipping occurs at 15.3 Watts. My supply rails dropped to +/-17.15V. (Scope is set to 5V/div.) Next, I hooked it up to a 4-Ohm resistive dummy load. Here's what I got:
An externally hosted image should be here but it was not working when we last tested it.
24.5 Watts into 4-Ohms. Not bad... Feeling confident, I plugged this cheap amp into the Rogue PA's +/-49.5V supply. Starting with the 8-Ohm speaker, I got this:
An externally hosted image should be here but it was not working when we last tested it.
Scope is now set to 10V/div, and that's a pretty clean 103 Watts we're seeing. Plugging in the dummy load yields 128.8 Watts into 4-Ohms. It could probably do more, but that's all my supply can source. Here's the picture:
An externally hosted image should be here but it was not working when we last tested it.
In all of these pictures, the voltmeter shows the (close to RMS) voltage across the output.
So Mr. Fisher's amp works. Earlier in this thread, Gaetan8888 posted a link to another amp design that didn't get much criticism. I repeat it here:
http://www.elecfree.com/circuit/powe...3055-with-pcb/
Notice that these designs are nearly identical except that Mr. Fisher's design uses darlingtons to eliminate some more parts. It also uses 3 bias diodes as I did. Here's why. When using only 2 diodes, a slight amount of crossover distortion can be seen at low signal levels. Here's the picture:
An externally hosted image should be here but it was not working when we last tested it.
It's small and hard to see, but it's there. Here it is with 3 diodes:
An externally hosted image should be here but it was not working when we last tested it.
My biggest concern with this amp is that it does not have short-circuit protection. It will fry the output transistors in an instant if you short the output -- even at low signal levels. I think it would be worth the added cost of 2 small transistors, 2 diodes and 4 resistors. These extra parts go for pennies. Instead what I did was to put a fuse in line with the speaker out. Don't worry, I won't put a 15A fuse in it. It will be a 7A fast-blow.
I see no stability problems with this amp. It works fine. It doesn't squeal and it doesn't smoke. All of my tests were on the bench. I'll be using it for some program material soon and will post my results. Here's what the finished repair looks like:
An externally hosted image should be here but it was not working when we last tested it.
I don't have a distortion meter so I can't tell you how it's fidelity is, but my guess is that it's not too terribly bad. It's definitely not audiophile gear, but it's not total lo-fi either.
If you built it and it doesn't work, you did something wrong because I am convinced, this design works.
Why dident you clean the soot and old crap off the heatsink ?
Anyways i don't see why this amp should be a piece of crap, its not much different from the old harman kardon citation 12, unless that was a piece of crap too.
I guess its the use of TIP142/147 together with low voltage transistors and 40+V rails that makes ppl react negatively. Though the bias circuitry is a bit shoddy but adding a Vbe multiplier is easy and should improve thermal stability alot.
Anyways i don't see why this amp should be a piece of crap, its not much different from the old harman kardon citation 12, unless that was a piece of crap too.
I guess its the use of TIP142/147 together with low voltage transistors and 40+V rails that makes ppl react negatively. Though the bias circuitry is a bit shoddy but adding a Vbe multiplier is easy and should improve thermal stability alot.
Last edited:
Same reason I built this amp instead of something more complicated.
Besides, its charred appearance gives it character. Makes it look like an old pirate -- hook, wooden leg, eye patch and all.I forgot to mention, I took quiescent current measurements if anyone is interested.
+/-18V Rail: -side... 5.76ma; +side... 2.42ma
+/-49.5V Rail: -side... 10.0ma; +side... 6.1ma
A little unbalanced, probably because of the parts variation. This is likely the reason the negative half of the waveform clips a bit sooner than the positive half. Still, it's quite acceptable.
no.
that tells you that 3.9mA is flowing in the Pgrnd.
All you do is identify all the Pgrnd currents in the PCB and check that they total 3.9mA.
If not, then there is an unintended current going to, or coming from, somewhere that is not accounted for.
I don't understand what you are referring to as Pgrnd. Could you please be a little more specific? The schematic I'm working with is here:
An externally hosted image should be here but it was not working when we last tested it.
"its not much different from the old harman kardon citation 12"
http://europa.spaceports.com/~fishbake/amp/a100.jpg
http://europa.spaceports.com/~fishbake/amp/a100.jpg
D3, yes but R10, R12 are part of an RC filter (with C9,C10). Reduce ripple and work to isolate the front end rails from the output stage.
There isn't a good reason for not using a Zobel and output inductor but there can be several bad consequences if you don't.
Misplaced pride or laziness can be costly.
Still, you amps, you bux.
For those others that are following this thread: it is good solid design to include the Zobel and output inductor on any amp build - they protect the amp from the speaker load inductance and capacitance.
The only reason i don't use these is that i have never ran into conditions that required them to be used, and i've disconnected speakers whhile my amps have been playing with no problem.
Though i have thought about atleast sticking the zobels onto the solder side of the speaker terminals as a "just in case" kinda thing.
The inductor however i dont see what good it could do, in my opinion it likely does more bad than good.
The RC filter for the LTP is not needed, this i've only seen in very old amps like the citation 12 that dident use as large caps as todays amplifiers and with topologies that have a overall mediocre to poor PSRR.
Not to mention that i've seen schematics from reputable designers here on the forum that dont use the zobel link and output inductor either.
Though i actually cannot know for sure that my amps dont oscillate since my test gesar is limited to 25MHz, above that im blind, so theres a slight chance that my amps still oscillate wirdly, maybe not rail to rail, but like fuzzyness on the peaks of the waveform, just that i cant see it cuz its too high in freq.
I guess the lack of interest in my threads and lack of ppl trying to build them is based on that i dont use these vital safety components and that i may actually seem like i dont quite know what im doing or that my "designs" are more or less direct replicas of already popular circuit built by others.
Though i have thought about atleast sticking the zobels onto the solder side of the speaker terminals as a "just in case" kinda thing.
The inductor however i dont see what good it could do, in my opinion it likely does more bad than good.
The RC filter for the LTP is not needed, this i've only seen in very old amps like the citation 12 that dident use as large caps as todays amplifiers and with topologies that have a overall mediocre to poor PSRR.
Not to mention that i've seen schematics from reputable designers here on the forum that dont use the zobel link and output inductor either.
Though i actually cannot know for sure that my amps dont oscillate since my test gesar is limited to 25MHz, above that im blind, so theres a slight chance that my amps still oscillate wirdly, maybe not rail to rail, but like fuzzyness on the peaks of the waveform, just that i cant see it cuz its too high in freq.
I guess the lack of interest in my threads and lack of ppl trying to build them is based on that i dont use these vital safety components and that i may actually seem like i dont quite know what im doing or that my "designs" are more or less direct replicas of already popular circuit built by others.
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