For 2SK170 is typically 10V in the data sheet. 9V battery is handy, and matching is another thing than producing spec. It takes about 5 mins for each one to really stop climbing fractions of mA BTW. Your differences are mainly due to temp variation. Hold one for a little and it will pull more. It will also pull a bit more when in a box hosting a CCT with elevated temp. Did you find enough 4mA? What is the mean average of your GR batch?
Salas,
I will try again with a fresh battery. There were about 12 items at 4.2 ma only 2 at 4.0ma, likely 4.2 is near enough. There were 4 or 5 at 4.1 and 4.3 values. I see in the CCT that Q4 and Q5 are in series should they be exactly matched or should one be a little less than the other?
DT
I will try again with a fresh battery. There were about 12 items at 4.2 ma only 2 at 4.0ma, likely 4.2 is near enough. There were 4 or 5 at 4.1 and 4.3 values. I see in the CCT that Q4 and Q5 are in series should they be exactly matched or should one be a little less than the other?
DT
Salas,
When I get home I will put the data into a spread sheet and report the the weighted mean.
DT
The lower one in the buffer can be the lower IDSS of the two. Just match per channel per position. There is bias voltage and a blocking cap, its not DC coupled symmetrical like in my DCB1 so to match between pair for better offset.
My take of the Salas Shunt V1.2
Thought I would post some progress made on the next upgrade to my simplistic jfet RIAA. In the photos you can see the assemblage of a V1.2 shunt regulator. This is as compact as I think I can make it. Polyprop MKP capacitors mounted underneath the circuit. Component size is critical and I made several errors in ordering so I am presently waiting for my next shipment of resistors before I install the FETS and BJT's. Both channels are matched to .1% so far. Can't wait to see if this thing powers up in a stable fashion. One of the dangers is that it doesn't work as there is not much room for corrections and addons.
I put a US penny in for size comparison
Thought I would post some progress made on the next upgrade to my simplistic jfet RIAA. In the photos you can see the assemblage of a V1.2 shunt regulator. This is as compact as I think I can make it. Polyprop MKP capacitors mounted underneath the circuit. Component size is critical and I made several errors in ordering so I am presently waiting for my next shipment of resistors before I install the FETS and BJT's. Both channels are matched to .1% so far. Can't wait to see if this thing powers up in a stable fashion. One of the dangers is that it doesn't work as there is not much room for corrections and addons.
I put a US penny in for size comparison
Attachments
Hi,
Has anyone tried any of these caps in the riaa ?
The values seem perfect.
Vishay R. Film Caps
Thanks
Has anyone tried any of these caps in the riaa ?
The values seem perfect.
Vishay R. Film Caps
Thanks
Hello
I ordered some 2 days ago for my RIAA project. I read a couple of recommendations on the www they are not high cost. Plus they are 1% values. I will report back.
DT
Hello Salas,
I put my IDSS measurements of the 2SK170 GR’s in a spreadsheet. The calculated Mean is 5.6ma the Median is 3.8ma. The Mean is skewed due to 52 items having IDSS measurements above 6.5ma. The JFETs do not appear to be from the same batch. Possibly leftovers in the bottom of a box somewhere. The stencil markings are different date codes and colors. An interesting process.
I went on ebay and bought a “batch” of BL’s to measure next. They were listed as recent single manufacture date.
My first attempt at this RIAA build will be with the 4ma GR’s. As I have ordered the complementary parts.
DT
All just for fun!
Hi,
6.5mA is the top limit for Idss gr grade when Vds is =10V and Tj is =25degC.
Either these high value are bl grade or above or your testing method is inaccurate or wrong.
6.5mA is the top limit for Idss gr grade when Vds is =10V and Tj is =25degC.
Either these high value are bl grade or above or your testing method is inaccurate or wrong.
I ordered thetubestore.com link here: Ampohm Paper in Oil, Copper Foil Capacitor 0.100µF / 630V two matched pair Ampohm Paper in Oil, Copper Foil Capacitor 0.100µF / 630V for interstage instead the Russian teflons FT-3
I ordered also audiohum.com link here: https://tienda.acens.com/epages/audiohum_es.sf/secDhF72qoB9Lg/?ObjectPath=/Shops/audiohum_es/Products/1310603300 two matched pair Mundorf MCap Silver Gold Oil 3,3uF /1200VDC for output cap instead the Obbligatos
Photo 10uF but I ordered 3,3uF
I ordered also audiohum.com link here: https://tienda.acens.com/epages/audiohum_es.sf/secDhF72qoB9Lg/?ObjectPath=/Shops/audiohum_es/Products/1310603300 two matched pair Mundorf MCap Silver Gold Oil 3,3uF /1200VDC for output cap instead the Obbligatos
An externally hosted image should be here but it was not working when we last tested it.
Photo 10uF but I ordered 3,3uF
Merlin and Salas,
Please let me know how they compare to FT-3. I am happy with the FT-3, but just adding to my wish list for future.
Please let me know how they compare to FT-3. I am happy with the FT-3, but just adding to my wish list for future.
I don't know if it is a better combination yet, I am just experimenting. System depending things.
I prefer copper foil over aluminium foil but as Salas said all depends own combination but I will try to compare, I will let you know hor performs in mine combination.
If made with expensive components, precise, and double mono its a very costly affair for DIY. That one I made it for a friend who bought expensive components. He wanted to upgrade from the first non cascoded version he had for long. Since he likes the concept very much he chose to splash out this time. To find matched resistors for Riaa amongst those Shinkoh for instance is very dear since more than used have to be bought and not all values are available. To match those Riaa 5% caps you get 2-3 fully matched sets among 40pcs. I hope it will prove worthy to him.
Hello AndrewT,
I do not know about your assumptions. My kitchen table is not a clean room lab. Yes something is odd with the measured IDSS values. The items are labeled GR. I followed the procedures listed here. This is not the first time the data sheet did not match the world. Part of the fun is sorting this stuff out.
DT
All just for fun!
Although I haven't used many GR, most I have come across (imported from German established vendor with real shops and distributed some times here among 2 shops) they ranged from 3.7-5.2mA.
In this one they are very close, its not like the Jensen. The copper is a bit more focused in voices, the alu more even handed. Its a matter of a combination with resistors. I would lean towards the Cu if with foil resistors too.
this seems to confirm that the "gr grade" has other higher Idss samples mixed in with the batch or that the measuring is wrong and/or inaccurate.