maybe to have us puzzled?
two things - lesser load seen by source ...... and higher influence of interconnects
though , first one is important , second one is almost a joke , in this case
two things - lesser load seen by source ...... and higher influence of interconnects
though , first one is important , second one is almost a joke , in this case
I really don't know.
It seems like if he wanted to rise R7 in Aleph 30 to (100K) to put in C8 (10pF), that do not exist in Aleph 3, to put down the gain at high frequencies.
But, if that's true, what was he trying to fix in Aleph 30 that did not happen in Aleph 3?
A look at the Aleph 3 revisited shows that he did not touch in this part of the circuit. If Aleph 3 had something to be fix there, he surely would fix in that revision.
I would be glad if Nelson Pass himself could put a light in that question.
Unless that someone else knows the secret and can share it with us.
It seems like if he wanted to rise R7 in Aleph 30 to (100K) to put in C8 (10pF), that do not exist in Aleph 3, to put down the gain at high frequencies.
But, if that's true, what was he trying to fix in Aleph 30 that did not happen in Aleph 3?
A look at the Aleph 3 revisited shows that he did not touch in this part of the circuit. If Aleph 3 had something to be fix there, he surely would fix in that revision.
I would be glad if Nelson Pass himself could put a light in that question.
Unless that someone else knows the secret and can share it with us.
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you need to learn few things , but in broader context
there are myriad of books about analog amplifiers , take any and read
that 10pF is so called lag cap and , when appropriately dimensioned , it's not having any influence on amplifier's hearing bandwidth
role of lag cap is to decrease amp's gain in UHF (or so ) increasing feedback , thus decreasing possibility of oscilations etc.
there are myriad of books about analog amplifiers , take any and read
that 10pF is so called lag cap and , when appropriately dimensioned , it's not having any influence on amplifier's hearing bandwidth
role of lag cap is to decrease amp's gain in UHF (or so ) increasing feedback , thus decreasing possibility of oscilations etc.
Zen, that's exactly what i said, put down ( i mean to decrease) the gain at high frequencies. I just did not know how to name it.
The question goes on: why it is not used in Aleph 3? The circuits are almost the same: why Aleph 30 is prone to oscilation and need this correction and Aleph 3 doesn't? And the very first question: Why to change from 10k/1k to 100k/10k?
I have A LOT of things to learn and I appreciate and thank you for your attention trying to teach me. I've been learned a lot of things with your posts and the other friends's posts along the forum.
Thank you all
The question goes on: why it is not used in Aleph 3? The circuits are almost the same: why Aleph 30 is prone to oscilation and need this correction and Aleph 3 doesn't? And the very first question: Why to change from 10k/1k to 100k/10k?
I have A LOT of things to learn and I appreciate and thank you for your attention trying to teach me. I've been learned a lot of things with your posts and the other friends's posts along the forum.
Thank you all
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well , if you re-read what I wrote , you'll spot that you already have your answers ;
values of resistors used in input impedance former /feedback net are not so arbitrary ; both sides of input LTP (differential amplifier) need to be so-so same , regarding effective impedances ; well , not exactly but that's usual and good practice.
in the other hand , value of those resistor net(s) is defining how strong is source of energy needed for those input electrodes (both sides , again ) ....... if you put lower resistance between said gates and actual source (CD or preamp , with some kind of pot in between) , you'll need more muscle for transferring all nuances - remember mentioned inherent capacitances of mosfets - you can imagine them as small water buckets , needing constant filling and emptying
so - small value resistors means bigger hose dia , demanding powerful pump
however - when using higher value resistance , that means smaller dia hose (pump sees smaller buckets , so no hurry needed) , demanding smaller (and usually finer) pump to feed it
price is - if you want finer pump , smaller dia hose , smaller buckets you need to compensate for those inherent capacitances - and lag cap is "just" one of ways to compensate
good reading for you - go to PL and FW site , download all pdf files and read ; not just thematic articles - read everything ..... and after some time (hopefully/necessary elbow grease , too ) you'll be able to read also between the lines
in a meantime, some reading : - Google Search
you can start with http://tinyurl.com/qfqxqfl , or - as light evening read with this piece:
http://www.firstwatt.com/pdf/art_diy_opamp.pdf
values of resistors used in input impedance former /feedback net are not so arbitrary ; both sides of input LTP (differential amplifier) need to be so-so same , regarding effective impedances ; well , not exactly but that's usual and good practice.
in the other hand , value of those resistor net(s) is defining how strong is source of energy needed for those input electrodes (both sides , again ) ....... if you put lower resistance between said gates and actual source (CD or preamp , with some kind of pot in between) , you'll need more muscle for transferring all nuances - remember mentioned inherent capacitances of mosfets - you can imagine them as small water buckets , needing constant filling and emptying
so - small value resistors means bigger hose dia , demanding powerful pump
however - when using higher value resistance , that means smaller dia hose (pump sees smaller buckets , so no hurry needed) , demanding smaller (and usually finer) pump to feed it
price is - if you want finer pump , smaller dia hose , smaller buckets you need to compensate for those inherent capacitances - and lag cap is "just" one of ways to compensate
good reading for you - go to PL and FW site , download all pdf files and read ; not just thematic articles - read everything ..... and after some time (hopefully/necessary elbow grease , too ) you'll be able to read also between the lines
in a meantime, some reading : - Google Search
you can start with http://tinyurl.com/qfqxqfl , or - as light evening read with this piece:
http://www.firstwatt.com/pdf/art_diy_opamp.pdf
Zen Mod, my friend (can i call you that way?)
Thank you very much, I start to see the light!!!
I understood all you explained. Just tell me what are "PL site", i think FW site means First Watt site. I read a lot there, but i will read "everything" as you are indicating.
I like reading and studying. I am 51 years old. I studied analog and OP amplifiers at school when i was 17 years old. By the years i worked with digital and security electronics, including fire security systems but i thing it will be easy to understand what i will read, because someday i already knew.
Thank you again for your kind explanation.
When i started studying to build the Aleph I did concentrate on Heatsink and thermal implications, I have a good knowledge about power supply but i am still weak about amplification and feedback. I will make my best to correct this.
Thank you again. Sincerely yours.
Fábio
Thank you very much, I start to see the light!!!
I understood all you explained. Just tell me what are "PL site", i think FW site means First Watt site. I read a lot there, but i will read "everything" as you are indicating.
I like reading and studying. I am 51 years old. I studied analog and OP amplifiers at school when i was 17 years old. By the years i worked with digital and security electronics, including fire security systems but i thing it will be easy to understand what i will read, because someday i already knew.
Thank you again for your kind explanation.
When i started studying to build the Aleph I did concentrate on Heatsink and thermal implications, I have a good knowledge about power supply but i am still weak about amplification and feedback. I will make my best to correct this.
Thank you again. Sincerely yours.
Fábio
ZEN MOD Where do you live?
Zen,
sorry been so intrusive but i always wanted to know where you are from.
If this question do not bother you, could you tell me?
I am from Salvador - Bahia - Brazil.
I am using this post to learn how to upload images, so in a near future i will
post some photos from my Alephs
Zen,
sorry been so intrusive but i always wanted to know where you are from.
If this question do not bother you, could you tell me?
I am from Salvador - Bahia - Brazil.
I am using this post to learn how to upload images, so in a near future i will
post some photos from my Alephs
Attachments
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well , I'm not so far from Brasil
😉
https://www.google.com/maps/place/J...2!3m1!1s0x475c9c4aa623c2d1:0x793eb1269113f385
😉
https://www.google.com/maps/place/J...2!3m1!1s0x475c9c4aa623c2d1:0x793eb1269113f385
Besides the beautiful country, you have one of the most important cultures of the world and amazing history to be proud of. Thanks for sharing...
I need a little more gain from my aleph 3 but i don't want balanced input or higher input impedance so i changed the R104 to 20k to get 26dB. Is there any drawback in that?
As i am using just 2 mosfet and not using the over current protection circuit from aleph 3, can i take off the 0r47 ohm from the source of the botton mosfet? Is there any drawback in this?
no
it's there from several reasons - bias temp. stability , open loop gain , THD spectra etc.
leave it as is
it's there from several reasons - bias temp. stability , open loop gain , THD spectra etc.
leave it as is
Referring to Nelson's Schematic.
I was going to do this many years ago but that bloody Juma told me it wasn't a good idea.
Next time I am going to trust my dumb ideas.
Hahahaha
I will pull out my old Aleph amp and start performing the mods.
Thanks Nelson
I was going to do this many years ago but that bloody Juma told me it wasn't a good idea.
Next time I am going to trust my dumb ideas.
Hahahaha
I will pull out my old Aleph amp and start performing the mods.
Thanks Nelson
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I have some extra heatsinks from BBA3 build.
Is it worthwhile giving front end a bit more current
Is it worthwhile giving front end a bit more current
Anything is improvement over irf9610. BC560C will do even a better job.
2sj313 at 10mA is a waste of a good part. There are much better ways to use it.