I'm confused too. Can you explain the attached pics from post #2471? There is no sum in those shots? is your m in those shots?
Can you take a pic of your scope front panel clearly showing the Vert controls?
Can you take a pic of your scope front panel clearly showing the Vert controls?
Yes, exactly! Is pic 1 Output ch 1 and 2 at the same time but no scope math? Pic 2 is the Sum of ch 1 and 2 (your m). Pic 3 is the one we didn't have but actually needed? The difference in ch 1 and 2 (ch1 - ch 2)?
Yes, Pic 2 is channel 1 + channel 2, you can see "1+2" on the screen (and that is indeed my "M" wave), pic 3 is with channel 2 inverted, i.e. channel 1 - channel 2, you can see "1-2" on the screen.
I don't know if my output is OK or not and don't understand why I have to invert channel 2 to get a decent looking output waveform.
I don't know if my output is OK or not and don't understand why I have to invert channel 2 to get a decent looking output waveform.
Jason, Your 1st scope shot shows you what you need in order to understand. The first scope shot shows that when the output of channel1 is +5V, the op of channel 2 is -5V. This is as it should be.
If you sum +5V and -5V you get zero (well not quite due to imperfections in the amp so the voltages are not precisely equal). This is what your Pic 2 is showing.
If you invert one of the channels to do the scope math you get 10V. Again what it should be.
If you sum +5V and -5V you get zero (well not quite due to imperfections in the amp so the voltages are not precisely equal). This is what your Pic 2 is showing.
If you invert one of the channels to do the scope math you get 10V. Again what it should be.
Many thanks for your explanation - seems that everything is in order and I was just being thick! (sorry).
The second picture with the summed outputs that should be zero are 1v pk-pk, that's quite a significant amount of voltage difference error. Is that something that can (or should be) improved (better matching of the two halves of the amplifier) or not to worry about it?
The second picture with the summed outputs that should be zero are 1v pk-pk, that's quite a significant amount of voltage difference error. Is that something that can (or should be) improved (better matching of the two halves of the amplifier) or not to worry about it?
I'm building Aleph-X (Grey's original 15V circuit), and I just received my heatsinks. For about 135watt dissipation/channel, I figure that I need a heatsink of 0.18 C/W per channel. To count for some loss, I ordered 2 heatsinks (one for each channel) rated at 0.15 C/W. The heatsink is nothing fancy, 400mm wide with 83mm tall fins.
What strucks me, is that those heatsinks are HEAVY! The packet weighs 20 kilograms, which means that one heatsink weighs 10 kg.
I plan to make dual mono aleph-x in one chassis. I cannot imagine having 2 toroidal transformers + 2 heatsinks in one chassis. It will weigh like an elephant. Is this normal???
I admit that I have never built a class A amp before...
What strucks me, is that those heatsinks are HEAVY! The packet weighs 20 kilograms, which means that one heatsink weighs 10 kg.
I plan to make dual mono aleph-x in one chassis. I cannot imagine having 2 toroidal transformers + 2 heatsinks in one chassis. It will weigh like an elephant. Is this normal???

I admit that I have never built a class A amp before...
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Sianturi,
With the dissapation you are dealing with, I wouldn't consider it
abnormal.
Since you are going dual-mono, have you considered straight mono
design instead?
Good luck with your build.
Cheers,
Dennis
With the dissapation you are dealing with, I wouldn't consider it
abnormal.
Since you are going dual-mono, have you considered straight mono
design instead?
Good luck with your build.
Cheers,
Dennis
Yeah... I think you're right. I did some search, and found
an Aleph-X weighing more than 50kg (stereo in a single chassis)!
I did consider a straight mono design, but the chassis will be very ugly since it will be assymetrical (i.e. only one heatsink in one side of the chassis).
an Aleph-X weighing more than 50kg (stereo in a single chassis)!
I did consider a straight mono design, but the chassis will be very ugly since it will be assymetrical (i.e. only one heatsink in one side of the chassis).
Very nice Leikis! I'm thinking of fixing the trannies like you did here. How many watts can your amp deliver to the loudspeaker? Your heatsink looks small.
Very nice Leikis! I'm thinking of fixing the trannies like you did here. How many watts can your amp deliver to the loudspeaker? Your heatsink looks small.
Thanks.
The toroids is 18v, so i suppose its around 25w ?
The heatsinks have big finns so lets hope its enough 🙂
88000uF for eatch channel, and one 400VA for eatch channel.
Attachments
Hi I have an old project that needs dusting off in loft ..... from memory I am missing
a matched set of output transistors ..... that are matched can anybody help me?
Richard
a matched set of output transistors ..... that are matched can anybody help me?
Richard
Hi sorry - my project is an Aleph-X ....... and I need matched power transistors .........
can anybody help...from memory I am going for 8 per amp ..... and need 16 in total
can anybody help...from memory I am going for 8 per amp ..... and need 16 in total
do not go with less of 3 pairs per side , so having 3 in each quadrant , for sum of 12 per channel
only same sex matched , so choice is :
case one : 2 triplets of N and 2 triplets of P type or
case two: one N type sextet and one P type sextet per channel
case two if you are nit-picky
contact member h_a for mosfets
only same sex matched , so choice is :
case one : 2 triplets of N and 2 triplets of P type or
case two: one N type sextet and one P type sextet per channel
case two if you are nit-picky
contact member h_a for mosfets
Yeah... I think you're right. I did consider a straight mono design, but the chassis will be very ugly since it will be assymetrical (i.e. only one heatsink in one side of the chassis).
I don't find that ugly especially when the 2 chassis' are right next to each other and they are made a mirror image of each other. The sides without sinks close together. That way there is a heatsink on the outside of each side of the pair: Symmetrical AND clever looking!: http://www.diyaudio.com/store/amplifier-kits/amp-camp-kit-23/aca-chassis.html
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Believe me... i saw those chassis before. But not my cup of tea. Cheers.I don't find that ugly especially when the 2 chassis' are right next to each other and they are made a mirror image of each other. The sides without sinks close together. That way there is a heatsink on the outside of each side of the pair: Symmetrical AND clever looking!: http://www.diyaudio.com/store/amplifier-kits/amp-camp-kit-23/aca-chassis.html
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