Yes, this project is a very good thing. I second this project (because my opinion is SO important 😆)."If I was left with the choice of ACA Mini vs. LU1014D Small Amplifier"
Monet or Picasso?
It's not that one is better, both are interesting.
A good question.
There are 2 reasons to cascode.
First LU1014D can only take 24 Volt.
This is why I use 12V+12V = 24V
In Nelson Pass circuits he has used high voltage = 40V.
He just have to cascode.
Second reason is to improve the linear operation of LU1014D.
Why my circuit works is because oof the Global Negative Feedback to input devices.
It is probably true LU1014D should work better with cascode.
But in my circuit there is no good possibility with that.
The lower LU1014 is a constant current source and the upper will swing.
PCB files are on the way for post 143. The amplifier.
2 guys have promised to do PCB files.
You just have to wait a couple of days.
One guy will do Sprint Layout 6.0 files.
The other I don't know. He maybe can do Gerber files ...
I see Sprint Layout 6.0 can import and export Gerber files.
I will ask them to also do PCB files for post 147 - The power supply.
2 guys have promised to do PCB files.
You just have to wait a couple of days.
One guy will do Sprint Layout 6.0 files.
The other I don't know. He maybe can do Gerber files ...
I see Sprint Layout 6.0 can import and export Gerber files.
I will ask them to also do PCB files for post 147 - The power supply.
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Nice initiative, well done.
I suppose limiting the gain, as the frequency approaches very low values (DC), would be a good idea.... The PCB should probably have the option to insert a 100uF cap in series with R5. This will help tame the DC offset variations as well.
The input allows for differential sources to be connected... maybe the PCB should allow for this option as well.
The AMP power rail decoupling capacitor is too big. The main reservoir capacitor should be placed on the PS PCB; the AMP PCB should have a combination of decoupling capacitors that will keep the AMP PCB power supply rails' impedance at a very low level for a broad frequency spectrum range. Hence, something like a 4.7uF in combination with a 0.1uF film bypass will work well.
I suppose limiting the gain, as the frequency approaches very low values (DC), would be a good idea.... The PCB should probably have the option to insert a 100uF cap in series with R5. This will help tame the DC offset variations as well.
The input allows for differential sources to be connected... maybe the PCB should allow for this option as well.
The AMP power rail decoupling capacitor is too big. The main reservoir capacitor should be placed on the PS PCB; the AMP PCB should have a combination of decoupling capacitors that will keep the AMP PCB power supply rails' impedance at a very low level for a broad frequency spectrum range. Hence, something like a 4.7uF in combination with a 0.1uF film bypass will work well.
There is a thread started for this. Mounting.
https://www.diyaudio.com/community/threads/lu1014d-mounting-for-small-amplifier.397475/
I've started PCB design for both EVUL design and Lineups' in Altium Designer. I have a design I would like to share aswell... maybe it should go in this thread because it's sort of the same type of animal as the prior art. I have not built it yet but it's simple and sims pretty well. I'll leave it for the birds.
Q1 is Linear Systems J111A model.
Jeff
Q1 is Linear Systems J111A model.
Jeff
Attachments
100uF in series of R5.
When we get 3.0mA to feed the input then 1.5k should be to bias MOSFET ZVP3310A.
If the two J113 has good match.
I have a 10 Ohm trimpot in the sources of J113 pair for offset adjust. Can be somewhat bigger.
As these are JFET the bias current will be close to zero in input pair.
So, I will not put any capacitor to the R5.
Rail decoupling values.
Yes, as a matter this is something I should consider.
4.7uF seems too small. A film cap wont hurt.
Those big 4700u is to be right on rail start where PS is connected to amplifier. Hence close to the LU1014D stage.
When we get 3.0mA to feed the input then 1.5k should be to bias MOSFET ZVP3310A.
If the two J113 has good match.
I have a 10 Ohm trimpot in the sources of J113 pair for offset adjust. Can be somewhat bigger.
As these are JFET the bias current will be close to zero in input pair.
So, I will not put any capacitor to the R5.
Rail decoupling values.
Yes, as a matter this is something I should consider.
4.7uF seems too small. A film cap wont hurt.
Those big 4700u is to be right on rail start where PS is connected to amplifier. Hence close to the LU1014D stage.
I have updated schematic.
It is two small changes.
Both are for rail caps. 10uF and 4700uF.
Here is the new schematic:
That circuit of yours looks interesting.
After all LU1014D is close to Valves operation.
SRPP is also a technique use in tubes.
Well, not polypropylene. Not film cap.10 uF polycarbonate caps?
Make it a small electrolyt.
