Anaswers ...
Ricardo,
Thanks for all the info, I have now read 119 pages of the builders thread and had seen some comments from you and others regarding your RIAA approach and that it was flat compared to the stock values. Very useful the point about matching RIAA, better than 0.1%, now I have a benchmark. Never built a phono stage and so far the thread and your article have been very illuminating. Going just from the values would it be safe to say the Salas approach is an even more recessed mid-band than stock, and of course your approach ??
I really appreciate your reply as going through all the posts is truly exhausting.
I have also found answers to some of the other questions, for example questions 7 and 8, those caps are used to stop the oscillations.
Questions 3 and 4 were answered by the newest BOM R31 that I found while rummaging through these pages, all through hole now.
Question 2 is partially answered with BOM R31, where it says caps C6 to C11 are optional, but where do they go, why are they optional, not knowing their location it´s hard to decide whether or not I should go ahead and solder them or not. Perhaps when I see the board this will be answered. Maybe the answer lies further ahead from page 119 !!!
That still leaves questions 1, 5 and 9 unanswered.
As I am new to this build the changes and differences that have happened over time are far from obvious, so are the reasons for the changes.
Anyway, thanks for the help, comments and advice !!!
Manolo
Ricardo,
Thanks for all the info, I have now read 119 pages of the builders thread and had seen some comments from you and others regarding your RIAA approach and that it was flat compared to the stock values. Very useful the point about matching RIAA, better than 0.1%, now I have a benchmark. Never built a phono stage and so far the thread and your article have been very illuminating. Going just from the values would it be safe to say the Salas approach is an even more recessed mid-band than stock, and of course your approach ??
I really appreciate your reply as going through all the posts is truly exhausting.
I have also found answers to some of the other questions, for example questions 7 and 8, those caps are used to stop the oscillations.
Questions 3 and 4 were answered by the newest BOM R31 that I found while rummaging through these pages, all through hole now.
Question 2 is partially answered with BOM R31, where it says caps C6 to C11 are optional, but where do they go, why are they optional, not knowing their location it´s hard to decide whether or not I should go ahead and solder them or not. Perhaps when I see the board this will be answered. Maybe the answer lies further ahead from page 119 !!!
That still leaves questions 1, 5 and 9 unanswered.
As I am new to this build the changes and differences that have happened over time are far from obvious, so are the reasons for the changes.
Anyway, thanks for the help, comments and advice !!!
Manolo
@Rolle2k
I´d say take a look at the datasheet for the transistors pinouts
Seems that SA1930 and SA1381 pinouts differ!
Lucky You that You just need to turn around the 1930.
Oh, that's typical.. i looked the j-fets for pinout, but didn't look at the SA1930 pinout... great job there
I think the current i have today over 4,7R resistors are only the jfet current.. so this will probably be simple to fix then
Thanks alot Calvin!
Oh, that's typical.. i looked the j-fets for pinout, but didn't look at the SA1930 pinout... great job there
I think the current i have today over 4,7R resistors are only the jfet current.. so this will probably be simple to fix then
Thanks alot Calvin!
I think that this issue with the SA1930 came up here or over on the Calvin GB thread and it was easily fixed by turning the SA around.
It’s an easy mistake to make with these transistors and one that I almost made myself. Just the nagging question made me have a look at the DATA Sheet and realise.
Oh reverse pins.
Hi Manolo,
sorry it took me a while to get back to your questions..... By the way, all documents can be found through the link in my signature.
1.- As I commented before C91 and C92 are on the Amplifier Schematic but not on any BOM, why ?¿?
>> Finally I decided to not put them. They are not needed, as the shunt regulator is much better than any cap, anyway. In the R1 version they were needed because there was a different opamp that needed lower supply voltage, so there was something between the 18V and the opamp, and local filtering needed.
2.- C6, C7, C8, C9, C10, C11 on the PDF BOM are not on the Amplifier Schematic, ?¿?¿?
>> Those were put during layout. These are the supply caps that stabilize the current mirrors, they are SMD caps and go on the bottom side of the PCB.
3.- C4a, C4b, C3a, C3b appear as SMD on PDF BOM, but as through hole on Mouser BOM, which is correct ?¿?
>> These are Panasonic SMD type caps which are actually through-hole (quite unfortunate naming I must say - several people stumbled across this.....)
4.- C6a, C6b, C7a, C7b same thing.
>> Same answer here
5.- R104b, R204b are on the Regulator Schematic and show 1M Ohm, and on the PDF BOM no value, not on Mouser BOM.
>> You can ignore these. They were planned to adjust the current of the current sources in the regulator, but in the end its good enough with usual precision 10Ohm resistors, no finetuning needed.
6.- RIAA Caps not on Mouser BOM (Answered !!!!!)
7.- 470 pF Cap on Mouser BOM not on any Schematic.
>> These were added at a later stage, to improve oscillation margin in the current sources. Sorry I did not update the schematic, but they are shown in the assembly guide.
8.- 2700 pF cap on Mouser BOM not on any Schematic.
>> Same here.
9.- 1 Ohm resistor on Mouser BOM, not on any Schematic.
>> We thought with Frans to improve the oscillation margin a little bit by artificially worsening the caps C105 and C205, since people were putting too good caps here (== too low ESR), but finally we didnt. Just do not put too expensive caps in these places.
Hope that explains it all! happy bastling
alfred
sorry it took me a while to get back to your questions..... By the way, all documents can be found through the link in my signature.
1.- As I commented before C91 and C92 are on the Amplifier Schematic but not on any BOM, why ?¿?
>> Finally I decided to not put them. They are not needed, as the shunt regulator is much better than any cap, anyway. In the R1 version they were needed because there was a different opamp that needed lower supply voltage, so there was something between the 18V and the opamp, and local filtering needed.
2.- C6, C7, C8, C9, C10, C11 on the PDF BOM are not on the Amplifier Schematic, ?¿?¿?
>> Those were put during layout. These are the supply caps that stabilize the current mirrors, they are SMD caps and go on the bottom side of the PCB.
3.- C4a, C4b, C3a, C3b appear as SMD on PDF BOM, but as through hole on Mouser BOM, which is correct ?¿?
>> These are Panasonic SMD type caps which are actually through-hole (quite unfortunate naming I must say - several people stumbled across this.....)
4.- C6a, C6b, C7a, C7b same thing.
>> Same answer here
5.- R104b, R204b are on the Regulator Schematic and show 1M Ohm, and on the PDF BOM no value, not on Mouser BOM.
>> You can ignore these. They were planned to adjust the current of the current sources in the regulator, but in the end its good enough with usual precision 10Ohm resistors, no finetuning needed.
6.- RIAA Caps not on Mouser BOM (Answered !!!!!)
7.- 470 pF Cap on Mouser BOM not on any Schematic.
>> These were added at a later stage, to improve oscillation margin in the current sources. Sorry I did not update the schematic, but they are shown in the assembly guide.
8.- 2700 pF cap on Mouser BOM not on any Schematic.
>> Same here.
9.- 1 Ohm resistor on Mouser BOM, not on any Schematic.
>> We thought with Frans to improve the oscillation margin a little bit by artificially worsening the caps C105 and C205, since people were putting too good caps here (== too low ESR), but finally we didnt. Just do not put too expensive caps in these places.
Hope that explains it all! happy bastling
alfred
I think that this issue with the SA1930 came up here or over on the Calvin GB thread and it was easily fixed by turning the SA around.
It’s an easy mistake to make with these transistors and one that I almost made myself. Just the nagging question made me have a look at the DATA Sheet and realise.
Oh reverse pins.
Speaking of that - this will make it a bit hard mounting the heatsink.... how have you other guys solved this? (who have had the same trouble)
Hi RollE2K
Read Quan’s post 3096 and onwards.
http://www.diyaudio.com/forums/analogue-source/218625-paradise-builders-310.html
Which may help a little.
For using the 2SA1930 as far as I know Quan is the only one to have used them. I took the easy way out and used the 2SA1381 which keeps the heat sink flat.
I decided against having the sinks mounted under the board which may not be the best for heat dissipation or having them sticking up at right angles which uses up valuable case space.
Hi RollE2K
Read Quan’s post 3096 and onwards.
http://www.diyaudio.com/forums/analogue-source/218625-paradise-builders-310.html
Which may help a little.
For using the 2SA1930 as far as I know Quan is the only one to have used them. I took the easy way out and used the 2SA1381 which keeps the heat sink flat.
I decided against having the sinks mounted under the board which may not be the best for heat dissipation or having them sticking up at right angles which uses up valuable case space.
I'll check quan's post..
Otherwise i think i'll also order some 2SA1381's, since it will look alot better - and i'm perfectionist about stuff like this quite often. I think having them standing up, will be to high for my case (only around 63mm inside i think).
Anyway, thanks for all the help so far!
Yes good idea
That's what i ended up doing
Hope that the rest of your build goes well.
OK I have fired up my boards
I have went through all the referenced voltages in the power supply and mine are all within 0.1v of all the references
Same goes for all the amplifier test points all within 0.1V of references.
Problem is that DC offset was 0.6v at the output and input and pin 6 of opamp, also if I remove the loading resistor I get 5.38V at the signal input
I changed the 2x 150K resistors R43a & b to 8K2 and the offset has dropped to 210mv but it also looked like there is some oscillation so I fitted the compensation caps in the power supply but I only had 470pf and 10nf which has helped but I still see some oscillation ?
Any one have any ideas?, I have double checked the boards and transistors' and resisters all seem OK and the voltages are good just not sure offset voltages and don't want to connect it to the system until I'm sure its OK
Alan
I have went through all the referenced voltages in the power supply and mine are all within 0.1v of all the references
Same goes for all the amplifier test points all within 0.1V of references.
Problem is that DC offset was 0.6v at the output and input and pin 6 of opamp, also if I remove the loading resistor I get 5.38V at the signal input
I changed the 2x 150K resistors R43a & b to 8K2 and the offset has dropped to 210mv but it also looked like there is some oscillation so I fitted the compensation caps in the power supply but I only had 470pf and 10nf which has helped but I still see some oscillation ?
Any one have any ideas?, I have double checked the boards and transistors' and resisters all seem OK and the voltages are good just not sure offset voltages and don't want to connect it to the system until I'm sure its OK
Alan
Hi Alan
Just noticed your post.
Ok 600mv is a little high but 240mv is better.
Some things to try just to get the ball rolling.
Measure the offset with the lid on.
I think that paulski noticed the same high offset when measuring with the lid off.
I had 120mv with the lid off which dropped like a stone to 7mv with the lid on and fully warmed up.
I noticed that you have the fully vented case top and yes I was tempted also.
But those transistors are pretty sensitive to temp changes so.
Try covering the front vents on the top plate up to the shunt (Not all of the way as the shunt heat sink still needs to breathe a little) just with a mag to see if that helps stabilise things a little.
Having zeroed the front end with 10k what happens when you change to 10R?
If you’ve had no magic smoke then it’s looking good with just a few minor things to sort.
Give it a go.
Let us know
Just noticed your post.
Ok 600mv is a little high but 240mv is better.
Some things to try just to get the ball rolling.
Measure the offset with the lid on.
I think that paulski noticed the same high offset when measuring with the lid off.
I had 120mv with the lid off which dropped like a stone to 7mv with the lid on and fully warmed up.
I noticed that you have the fully vented case top and yes I was tempted also.
But those transistors are pretty sensitive to temp changes so.
Try covering the front vents on the top plate up to the shunt (Not all of the way as the shunt heat sink still needs to breathe a little) just with a mag to see if that helps stabilise things a little.
Having zeroed the front end with 10k what happens when you change to 10R?
If you’ve had no magic smoke then it’s looking good with just a few minor things to sort.
Give it a go.
Let us know
Oscilloscope
I have another question, I am in the process of buying an Oscilloscope, my first scope !!!!!
I have been looking at various options to purchase locally, and apart from finding multi-thousand dollar scopes that I can´t and won´t buy, I found two very reasonably priced ones:
1.- Uni-T 231 OSCP50, 50 Mhz, 50GS/s, 500 Ms/S, USB connection for a PC two channel scope
2.- Rigol DS1052E, 50 Mhz, 1 GSa/s, USB two channel scope.
I was wondering first if I need higher resolution say 100 Mhz, I don´t really think so, but would like to know what you suggest.
Both are brand new, three year warranty and have basically the same price.
I would appreciate comments and suggestions.
Saludos,
Manolo
I have another question, I am in the process of buying an Oscilloscope, my first scope !!!!!
I have been looking at various options to purchase locally, and apart from finding multi-thousand dollar scopes that I can´t and won´t buy, I found two very reasonably priced ones:
1.- Uni-T 231 OSCP50, 50 Mhz, 50GS/s, 500 Ms/S, USB connection for a PC two channel scope
2.- Rigol DS1052E, 50 Mhz, 1 GSa/s, USB two channel scope.
I was wondering first if I need higher resolution say 100 Mhz, I don´t really think so, but would like to know what you suggest.
Both are brand new, three year warranty and have basically the same price.
I would appreciate comments and suggestions.
Saludos,
Manolo
Why ?? Just for the sake of trying something different .....
Where ?? it would go in place instead of OPA134
I was just reading a document by Samuel Groner with measurements of multiple IC opamps including discrete ones, and in general discrete ones like the 990 in particular had better measurements than ICs.
He does not test the OPA 134, but there are sufficient ones tested as to honestly make me think a discrete one could work really well. I mean if it has less THD, better linearity etc., it could work really well in a phono stage. Just asking ...
Where ?? it would go in place instead of OPA134
I was just reading a document by Samuel Groner with measurements of multiple IC opamps including discrete ones, and in general discrete ones like the 990 in particular had better measurements than ICs.
He does not test the OPA 134, but there are sufficient ones tested as to honestly make me think a discrete one could work really well. I mean if it has less THD, better linearity etc., it could work really well in a phono stage. Just asking ...
3. SIGLENT SDS1102CNL Digital Oscilloscope 100MHz 2Ch 1GS/s USB 7" TFT LCD (100 MHz makes waveform anomalies show better).
4. RIGOL DS1074Z - 70MHz, 4 CHANNEL 7 Inch WVGA (800x480) deep memory scope. Pricier but better value. Has higher bandwidth than spec also.