The OPA134 is used as DC servo as already told. Because the servo acts as an integrator it drops in ampification to higher frequencies. By 1kHz gain is so low that distortion is not an issue. It is a good audio opamp anyway. Maybe ten years ago it was even found in Rowland equipment for example. A discrete Opamp will likely have less DC stability so at this point in the circuit it does not make much sense. When you want to improve on the DC specs use the OPA627. Some that did this even reported improved sound. Wishfull thinking ?
O.k, That is getting silly, it is the servo, so you see my 'why?' is still valid
(p.s. I see I'm repeating others
)
Last edited:
Silly me ...
Well now I see it´s silly, but when I asked I had no idea what a DC-Servo was, I am not trained in electronics, nor in electricity. Just got into this as a hobby a few years ago.
Every little bit I know I have been learning from simple books, like electricity and electronics for dummies, and from reading forums and articles, and from doing exactly this, looking at schematics and asking; and yes sometimes they are silly questions.
From looking at the schematic I had no way of knowing the use of that opamp, as I said I thought it was used in the way I had seen opamps used normally, as amplifiers, in this case of the audio signal. Now that I have seen and read about it, it is rather obvious.
I have never built a phono stage before either, that is why I am really excited about this build, it is very different from all other phono stages I have seen, and it has way more transistors than I have ever put together as well. Which is something I am also trying to understand.
Just yesterday I started reading on DC-Bias and DC-Servos, after I was told the opamps function. So yes it was silly ... but now that you are aware of my ignorance you can see why my questions and replies were valid as well ...
Saludos
Manolo
Well now I see it´s silly, but when I asked I had no idea what a DC-Servo was, I am not trained in electronics, nor in electricity. Just got into this as a hobby a few years ago.
Every little bit I know I have been learning from simple books, like electricity and electronics for dummies, and from reading forums and articles, and from doing exactly this, looking at schematics and asking; and yes sometimes they are silly questions.
From looking at the schematic I had no way of knowing the use of that opamp, as I said I thought it was used in the way I had seen opamps used normally, as amplifiers, in this case of the audio signal. Now that I have seen and read about it, it is rather obvious.
I have never built a phono stage before either, that is why I am really excited about this build, it is very different from all other phono stages I have seen, and it has way more transistors than I have ever put together as well. Which is something I am also trying to understand.
Just yesterday I started reading on DC-Bias and DC-Servos, after I was told the opamps function. So yes it was silly ... but now that you are aware of my ignorance you can see why my questions and replies were valid as well ...
Saludos
Manolo
Well now I see it´s silly, but when I asked I had no idea what a DC-Servo was, I am not trained in electronics, nor in electricity. Just got into this as a hobby a few years ago.
Every little bit I know I have been learning from simple books, like electricity and electronics for dummies, and from reading forums and articles, and from doing exactly this, looking at schematics and asking; and yes sometimes they are silly questions.
From looking at the schematic I had no way of knowing the use of that opamp, as I said I thought it was used in the way I had seen opamps used normally, as amplifiers, in this case of the audio signal. Now that I have seen and read about it, it is rather obvious.
I have never built a phono stage before either, that is why I am really excited about this build, it is very different from all other phono stages I have seen, and it has way more transistors than I have ever put together as well. Which is something I am also trying to understand.
Just yesterday I started reading on DC-Bias and DC-Servos, after I was told the opamps function. So yes it was silly ... but now that you are aware of my ignorance you can see why my questions and replies were valid as well ...
Saludos
Manolo
Manolo, do not take it (my remark) too serious, I was just kidding around (a bit). We all had too, and still are, learn. It is very commendable that you, a beginner, are sticking out your neck and make remarks here in the forum, keep doing that and you will earn/have respect.
Thanks FdW,
I will keep on asking don´t you worry, I mean there´s just so much stuff to learn, I actually regret not having taken some electronics courses when I was in the University, I took astronomy courses as optionals instead. I did do a minor (3 years) in engineering which included one semester of electricity, plus various other courses like thermodynamics, chemistry, physics, heaps of math but in general no real world applications of most of things I studied, way too much theory, demonstrations and proofs.
Actually they bored the &/%$/&$/% out of me, so I then went off to study business admin, and although this was many many many years ago, I still have some of the conceptual base and math needed, but of course not the formal training in any specific area, although having that base does help a lot. It has actually helped me plenty in my work as well, as I have worked for large chemical and mining companies, and as it turned out I could, if explained properly, understand very many of the things that were going on technically.
As I said in a previous post I am just starting to get serious and buying my first scope, (thanks Salas for the suggestions !!!!), and that will be another challenge to master to some degree the use of the scope !!! ...
Anyway thanks again for the patience, and don´t worry I have a thick skin so no offense taken at any point, just wanted you guys to know where I´m standing in terms of my audio skills,
!!!!
Saludos,
Manolo
I will keep on asking don´t you worry, I mean there´s just so much stuff to learn, I actually regret not having taken some electronics courses when I was in the University, I took astronomy courses as optionals instead. I did do a minor (3 years) in engineering which included one semester of electricity, plus various other courses like thermodynamics, chemistry, physics, heaps of math but in general no real world applications of most of things I studied, way too much theory, demonstrations and proofs.
Actually they bored the &/%$/&$/% out of me, so I then went off to study business admin, and although this was many many many years ago, I still have some of the conceptual base and math needed, but of course not the formal training in any specific area, although having that base does help a lot. It has actually helped me plenty in my work as well, as I have worked for large chemical and mining companies, and as it turned out I could, if explained properly, understand very many of the things that were going on technically.
As I said in a previous post I am just starting to get serious and buying my first scope, (thanks Salas for the suggestions !!!!), and that will be another challenge to master to some degree the use of the scope !!! ...
Anyway thanks again for the patience, and don´t worry I have a thick skin so no offense taken at any point, just wanted you guys to know where I´m standing in terms of my audio skills,
!!!!Saludos,
Manolo
Restart: Trannies for Calvin Buffer PCB's
Folks
There are in a couple of weeks some more Calvin Buffer PCB's on the marked. Thanks Alfred, well done
Now it make sence to restart my older GB , not only for stragglers.
Link to GB Trannies for Calvin:
http://www.diyaudio.com/forums/group-buys/243357-trannies-calvin-14.html
The trannies for The Calvin Buffers are selected to Stereo sets.
VHT/VGS J107 +/- 0,05 Volt ; PF 5102 +/- 0,025 Volt
Take care Werner
Folks
There are in a couple of weeks some more Calvin Buffer PCB's on the marked. Thanks Alfred, well done
Now it make sence to restart my older GB , not only for stragglers.
Link to GB Trannies for Calvin:
http://www.diyaudio.com/forums/group-buys/243357-trannies-calvin-14.html
The trannies for The Calvin Buffers are selected to Stereo sets.
VHT/VGS J107 +/- 0,05 Volt ; PF 5102 +/- 0,025 Volt
Take care Werner
https://docs.google.com/document/d/1fbEg76g_tv0dpwyTpGJQuue5GjYHLWBejaem_Q8d-tE/edit?pli=1
look at hesener`s documents - its all in there!
look at hesener`s documents - its all in there!
I guess I'm missing it Michael.
I saw the section in the docs on how to disable the onboard buffer but not a section that outlines the components that are redundant when using the Calvin buffer. I'll keep looking.
Hi,
You can omit with all original buffer parts, i.e. Q90/91/92/99 and the associated resistors R12/13/15.
You may insert the Calvin Buffer instead, with the exception of the 100k Input resistor R15.
R15 may only be needed if the Calvin Buffer is used as standalone subassembly.
You also would need to change a couple of resistors in the power supply to deal with the increased current demand.
jauu
Calvin
You can omit with all original buffer parts, i.e. Q90/91/92/99 and the associated resistors R12/13/15.
You may insert the Calvin Buffer instead, with the exception of the 100k Input resistor R15.
R15 may only be needed if the Calvin Buffer is used as standalone subassembly.
You also would need to change a couple of resistors in the power supply to deal with the increased current demand.
jauu
Calvin
Hi Howlingdawg
i used the 7.5ohm Value CCS resistor suggested by Frans which works well in my set up.
''About the Paradise PSU when using Calvin buffers
For the shunt to function it needs to consume a few mA’s (30mA is the design value, actual values from 25 up to 50mA are acceptable). This results in 30ma x 18V = 540mW and 110mA x 8V = 880mW constant power consumption in the voltage regulator (Shunt, CVS and CCS), the total power supply consumption is:
2 x ((30mA 18V) + (110mA 8V (26Vin – 18Vout))) = 2.8Watt
When connecting the Calvin buffer an additional 30mA needs to be supplied, the CCS setting needs to be changed from 110mA to 140mA, this can be done by changing the 10 Ohm resistors to 7.5 Ohm resistors. See the attached JPG (The attached screen shows the CCS current in the PSU for (E24) resistors from 4.7 to 10 Ohm (currents from 240…105mA (give or take a few mA’s)).
The ‘normal’ power supply dissipation now changes to:
2 x ((30mA 18V) + (140mA 8V (26Vin – 18Vout))) = 3.4Watt
This should not be a problem with the supplied heat sink, but care should be taken to ventilate the area surrounding the PSU heat sink.
When testing the PSU (with the RIAA and buffer disconnected) the total power consumption in the PSU will be 140mA x 26V = 7.3Watt. If the PSU is not placed in a closed box this should not be a problem, the heat sink may get hot (up to 70C or so) and should not be touched (but you will know (as a regular soldering iron user)).
As ever, be sure that the final enclosure is well ventilated (especially around the PSU).
Regards,
Frans''.
hope that helps
Myself i use 9.0ohm CCS resistor and i do have 138-139mA total current - which in my case should be enough, 80mA + 27mA (Paradise+Calvin) which is 107mA total current. So i have approx 30-33mA shunt current. It should probably be closer to 40mA since the old output stage is removed (was around 6mA i think).
I don't have the largest case for my boards, so i try to get minimum heat needed.
I don't have the largest case for my boards, so i try to get minimum heat needed.
Hello,
today I finally got around to install my Calvin buffers. I have two cases of "Shunt regulator LEDs do not light up – check for short circuits on the buffer or the connection"
Lights come up when I remove the buffers so it has to be on the buffers themselves (on both of them). I can't find any obvious shorts though. Any typical mistakes that lead to that error?
Many Thanks
Sven
today I finally got around to install my Calvin buffers. I have two cases of "Shunt regulator LEDs do not light up – check for short circuits on the buffer or the connection"
Lights come up when I remove the buffers so it has to be on the buffers themselves (on both of them). I can't find any obvious shorts though. Any typical mistakes that lead to that error?
Many Thanks
Sven
Last edited:
''When connecting the Calvin buffer an additional 30mA needs to be supplied, the CCS setting needs to be changed from 110mA to 140mA, this can be done by changing the 10 Ohm resistors to 7.5 Ohm resistors. See the attached JPG (The attached screen shows the CCS current in the PSU for (E24) resistors from 4.7 to 10 Ohm (currents from 240…105mA (give or take a few mA’s)).
The ‘normal’ power supply dissipation now changes to:
2 x ((30mA 18V) + (140mA 8V (26Vin – 18Vout))) = 3.4Watt
This should not be a problem with the supplied heat sink, but care should be taken to ventilate the area surrounding the PSU heat sink.
When testing the PSU (with the RIAA and buffer disconnected) the total power consumption in the PSU will be 140mA x 26V = 7.3Watt. If the PSU is not placed in a closed box this should not be a problem, the heat sink may get hot (up to 70C or so) and should not be touched (but you will know (as a regular soldering iron user)).
As ever, be sure that the final enclosure is well ventilated (especially around the PSU).''
Hi Sven
have you changed the 10ohm resitor? you may not be pulling enough current through the shunt.
and
did you build the Buffers to the updated boom? also did you leave out the 100K R15?
just wild guess work but.
The ‘normal’ power supply dissipation now changes to:
2 x ((30mA 18V) + (140mA 8V (26Vin – 18Vout))) = 3.4Watt
This should not be a problem with the supplied heat sink, but care should be taken to ventilate the area surrounding the PSU heat sink.
When testing the PSU (with the RIAA and buffer disconnected) the total power consumption in the PSU will be 140mA x 26V = 7.3Watt. If the PSU is not placed in a closed box this should not be a problem, the heat sink may get hot (up to 70C or so) and should not be touched (but you will know (as a regular soldering iron user)).
As ever, be sure that the final enclosure is well ventilated (especially around the PSU).''
Hi Sven
have you changed the 10ohm resitor? you may not be pulling enough current through the shunt.
and
did you build the Buffers to the updated boom? also did you leave out the 100K R15?
just wild guess work but.
Yes I did leave out R15 and I followed the few changes on the last page of the assembly guide. I don't have any visible shorts, I'm sure.
How about the pin layout of the output transistors - it seems the 2SA1381 is not different from the Fairchild BD14016STU I used. I assume the side with the writing faces up?
Beside the BD140 I used Fairchild J107 and PF5102 so the whole pin layout stuff should not be a problem?
How about the pin layout of the output transistors - it seems the 2SA1381 is not different from the Fairchild BD14016STU I used. I assume the side with the writing faces up?
Beside the BD140 I used Fairchild J107 and PF5102 so the whole pin layout stuff should not be a problem?
Last edited:
For me the 2SA1381 was kinda "short-legged" so i isolated the legs with teflon tubing - since they pretty much touched the sinks. Even though somewhere there it became a short - until i moved them a little bit closer to the solder-pads. Then the problem went away. So i would start checking there.
Also, check that the J-fets are in the right direction.
Also, check that the J-fets are in the right direction.