Hi everyone I am a newbie, my name is Eric,
I was wondering if anyone had experience with this design. It is a 70W single ended class A, I found in the French magazine LED #118 of April 1994. On fig.1 the IC1 is a LM144H, IC2 LM317L, IC3 LM337L , T1 MPS A 06, T2 MPS A 56. Fig. 2 will show T3 (and T4 for 4 Ohm) as a IRF 150 Mosfet with four LM317HVK.
Happy new year to all!
I was wondering if anyone had experience with this design. It is a 70W single ended class A, I found in the French magazine LED #118 of April 1994. On fig.1 the IC1 is a LM144H, IC2 LM317L, IC3 LM337L , T1 MPS A 06, T2 MPS A 56. Fig. 2 will show T3 (and T4 for 4 Ohm) as a IRF 150 Mosfet with four LM317HVK.
Happy new year to all!
Well then Eric, welcome to diyaudio! While I'm at it, and since nobody ever does it, I'll take this opportunity to greet you in french: bienvenue à DIYaudio, le meilleur site de renseignements sur l'audio et l'électronique sur l'internet!
So, are you a newbie to electronics, or just diyaudio? If you have not much experinece with audio and electronics, I wouldn' really recommend you start with such a project. But if you understand the schematic and how it works (just those transistors on the regulators for the LM144 are making me scratch my head) then go ahead and give it a try. Bear in mind you'll need a heck of a good transformer...
I love (not!) how the french (les québécois on fait pas ça) don't give you the NECESSARY information on how their ******* circuit works and the style of their litterature. They have a way of writing that seems so, well, philosophical and not technical at all. they like to complicate the sentances, maudit que ça m'écoeure! Ieven I find it bit difficult to understand, especially the fourth paragraph. They also don'T write the values on the components in this magazine. Maybe they have changed that since, I haven't picked up a French magazine in quite a while.
Popular electronics: now there was a magazine that kicked electronic rear-end. I guess the internet killed it. colisse d'internet! take that swearword engine
Oh well, have fun building it!
So, are you a newbie to electronics, or just diyaudio? If you have not much experinece with audio and electronics, I wouldn' really recommend you start with such a project. But if you understand the schematic and how it works (just those transistors on the regulators for the LM144 are making me scratch my head) then go ahead and give it a try. Bear in mind you'll need a heck of a good transformer...
I love (not!) how the french (les québécois on fait pas ça) don't give you the NECESSARY information on how their ******* circuit works and the style of their litterature. They have a way of writing that seems so, well, philosophical and not technical at all. they like to complicate the sentances, maudit que ça m'écoeure! Ieven I find it bit difficult to understand, especially the fourth paragraph. They also don'T write the values on the components in this magazine. Maybe they have changed that since, I haven't picked up a French magazine in quite a while.
Popular electronics: now there was a magazine that kicked electronic rear-end. I guess the internet killed it. colisse d'internet! take that swearword engine
Oh well, have fun building it!
Hi gain wire,
Thank you for the greeting. This project will be my second project, my first was a tube amp for headphones, from another french magazine....😉 It turned out well with a bit of effort to find parts and missing info...! As it stands I "think" I have enough info to complete this puppy and I will have a bit of help from a friend who is a electronic technician (although he is busy at times). Could you be more specific regarding your comment about the transistors? Regarding the transformer, I am planning on sticking with a local company who manufactures transformers, as I was very successful using their product in my first project (they also have a good reputation). I will use a toroidal transformer, perhaps adding a choke, if required.
Merci encore,
Eric
Thank you for the greeting. This project will be my second project, my first was a tube amp for headphones, from another french magazine....😉 It turned out well with a bit of effort to find parts and missing info...! As it stands I "think" I have enough info to complete this puppy and I will have a bit of help from a friend who is a electronic technician (although he is busy at times). Could you be more specific regarding your comment about the transistors? Regarding the transformer, I am planning on sticking with a local company who manufactures transformers, as I was very successful using their product in my first project (they also have a good reputation). I will use a toroidal transformer, perhaps adding a choke, if required.
Merci encore,
Eric
go ahead Arick
construct and let us now
i am also inetersted .... a better and more complete schematic will be a bless also
happy new year
construct and let us now
i am also inetersted .... a better and more complete schematic will be a bless also
happy new year
70w
70w single-ended output is a big thing.yuo will need a big transformer and biggest heatsinks -per channel.perhaps you should meditate over this project.
regards..............
70w single-ended output is a big thing.yuo will need a big transformer and biggest heatsinks -per channel.perhaps you should meditate over this project.
regards..............
those two output mosfets will require massive heatsink
schematics look simple, how do you adjust zero volts on output...is it with RV1?
schematics look simple, how do you adjust zero volts on output...is it with RV1?
70w
ic1 inverts the input signal(voltagegain is round about r2 divided trough r1).
rv1 is used to adjust the offset at the output.
the outputstage is se-class a without feedback.the voltageregulators ic4 to ic7 seemed to be used as constantcurrentsources(for the bias of the mosfets).
t1 and t2 are used as filter for the supply(capacitance multiplier) . ic2 and ic3 stabilise the supplyvoltage for ic1.
that`s what i presume when looking at the schematic.
regards.............
ic1 inverts the input signal(voltagegain is round about r2 divided trough r1).
rv1 is used to adjust the offset at the output.
the outputstage is se-class a without feedback.the voltageregulators ic4 to ic7 seemed to be used as constantcurrentsources(for the bias of the mosfets).
t1 and t2 are used as filter for the supply(capacitance multiplier) . ic2 and ic3 stabilise the supplyvoltage for ic1.
that`s what i presume when looking at the schematic.
regards.............
Re: 70w
Hi to all of you,
Sakis, the only other schematic is another simple one showing the power supply, If you are interested I can send you a copy of the document buy e-mail.
This amp is designed to be built as two mono blocks, I am already planning to use huge heat sinks, the recommended transformers are 500VA, I might increase that a bit...
Zero volt is adjusted with RV1 , after adjusting RV2 output to + 38V and RV3 to -38V. On the subject of heat sinks, I was suggested to keep one component per heat sink, electrically isolating the heat sinks from one other and from the case. Does it make any sense in the audio world???
Than you to all for your constructive comments,
Eric
Hi to all of you,
sakis said:
Sakis, the only other schematic is another simple one showing the power supply, If you are interested I can send you a copy of the document buy e-mail.
mjf said:
This amp is designed to be built as two mono blocks, I am already planning to use huge heat sinks, the recommended transformers are 500VA, I might increase that a bit...
adason said:
Zero volt is adjusted with RV1 , after adjusting RV2 output to + 38V and RV3 to -38V. On the subject of heat sinks, I was suggested to keep one component per heat sink, electrically isolating the heat sinks from one other and from the case. Does it make any sense in the audio world???
Than you to all for your constructive comments,
Eric
Almost forgot, I live in Canada where outside temperature go well bellow 0c or 32F and will use it as inside heater as well...
heatsinks
hallo.
i would not isolate the heatsinks from the (metall)case,because it could beginn to humm.
greetings............
hallo.
i would not isolate the heatsinks from the (metall)case,because it could beginn to humm.
greetings............
Can anyone explain to me what's the point of building a really bad sounding class A amp? Any number of class AB amps will wipe the floor with this thing.
Apparently, as the entire voltage gain has to come from the opamp, the circuit calls for a high voltage type, in this case working at +-28v if i'm not mistaken. The actual type is long obsolete but even if available, it is completely unacceptable for audio. And it's output stage works most likely in class B. So much for class A claims.
3-pin regulators make amazingly poor CCS. My guess is the current stops being very constant just above 1kHz.
And finally, the output MOSFETs get a real beating. Their number should be at least doubled for any kind of long term reliabilty.
One can only wonder why, given the availability of all Pass Labs designs, one would pick up a magazine design. It has always been my suspicion, such articles are written by people desperate to pay the rent, rather than leading audio designers.
Apparently, as the entire voltage gain has to come from the opamp, the circuit calls for a high voltage type, in this case working at +-28v if i'm not mistaken. The actual type is long obsolete but even if available, it is completely unacceptable for audio. And it's output stage works most likely in class B. So much for class A claims.
3-pin regulators make amazingly poor CCS. My guess is the current stops being very constant just above 1kHz.
And finally, the output MOSFETs get a real beating. Their number should be at least doubled for any kind of long term reliabilty.
One can only wonder why, given the availability of all Pass Labs designs, one would pick up a magazine design. It has always been my suspicion, such articles are written by people desperate to pay the rent, rather than leading audio designers.
analog_sa said:
Not that I like 3 pin regulators CCS's, but the AC performance is not necessary bad. I have measured for LM317 -75dB rejection @100KHz for Io=10mA, Vcc=24V Rload=1kohm.
Some recent LT, Linear, TI and National 3-pin regulators are even much better.
I feal something is missing in the translation. They may be talking about 70w power disipation not output power. Looking back to
the Pass A40 article a 40w rms single ended amp using a current
source will be disipating 200w per channel all the time. Look at
the classic Pass Zen amp it takes some serious heatsinking to
build even a 10w single ended amp.
the Pass A40 article a 40w rms single ended amp using a current
source will be disipating 200w per channel all the time. Look at
the classic Pass Zen amp it takes some serious heatsinking to
build even a 10w single ended amp.
analog_sa said:
That could easily be the case. If the builder is new to DIY, however,
one of the biggest advantages of Class A amplifiers is that you can
get very good performance with very simple circuits.
😎
syn08 said:
I very much doubt you will get the same performance @1A. Besides there are 4 in parallel, which makes the equivalent one perform 4 times worse. A very simple mosfet circuit will do so much better.
Then again, what do i know? Mr Pass seems to endorse the design
Thank you to all of you who posted constructive comments, I will keep you updated with the process. It may take a bit of time, as I have sadly other commitments in the way.
Eric
Eric
yeah Ithink woody is right when he says power DISSIPATION. if you get 70watts at the output, that means there's another 80 watts at least being dissipated in heat over those regulators. Kind of unbelievable, no?
also analog_sa, I guess yeah, that was one of those hi-voltage weird opamps, and we all should have seen this earlier: an opamp contains a class B output! (or is it class AB?) either way, you're right.
But still, it'll make an excellent project, and I can attest to the abilities of this circuit to be used as a heater: I sleep with my socks on up here... I could use a few MOSFETs to heat the floor!
also analog_sa, I guess yeah, that was one of those hi-voltage weird opamps, and we all should have seen this earlier: an opamp contains a class B output! (or is it class AB?) either way, you're right.
But still, it'll make an excellent project, and I can attest to the abilities of this circuit to be used as a heater: I sleep with my socks on up here... I could use a few MOSFETs to heat the floor!
Hello again, can't believe it has been that long since I posted something here! I am now working on this (heater) project again. First a picture of the power supply:
http://i496.photobucket.com/albums/rr324/ericrc30/IMG_5909.jpg
I was testing a C-L-C-L-C, I decided to keep the C-L-C, as it was enough to give this DC ripple at the end
http://i496.photobucket.com/albums/rr324/ericrc30/IMG_5911.jpg
basically, 0.001-0.002V DC (my voltmeter kept oscillating)
I also have the PCB populated and the heat sinks ready to receive the transistors. (pictures to come)
I have one questions for you guy's (and Lady's) out there. This design does not have an output capacitor and the article at the end calls to adjust RV-1 with a 8 ohms resistor at the outputs to get as close as 0 Volts DC on the outputs. Fine with me, however I found some similar design (very similar) to witch an output capacitor was added.
What should I do? with or without capacitor?
My concern is without it, if I have some kind of failure the speakers might get some DC😱
Is there some sort of "standard" out there regarding output capacitors?
Thank you,
more to come!
Eric
http://i496.photobucket.com/albums/rr324/ericrc30/IMG_5909.jpg
An externally hosted image should be here but it was not working when we last tested it.
I was testing a C-L-C-L-C, I decided to keep the C-L-C, as it was enough to give this DC ripple at the end
http://i496.photobucket.com/albums/rr324/ericrc30/IMG_5911.jpg
An externally hosted image should be here but it was not working when we last tested it.
basically, 0.001-0.002V DC (my voltmeter kept oscillating)
I also have the PCB populated and the heat sinks ready to receive the transistors. (pictures to come)
I have one questions for you guy's (and Lady's) out there. This design does not have an output capacitor and the article at the end calls to adjust RV-1 with a 8 ohms resistor at the outputs to get as close as 0 Volts DC on the outputs. Fine with me, however I found some similar design (very similar) to witch an output capacitor was added.
What should I do? with or without capacitor?
My concern is without it, if I have some kind of failure the speakers might get some DC😱
Is there some sort of "standard" out there regarding output capacitors?
Thank you,
more to come!
Eric
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