Hi Salas and everybody,
First I want to thank you and Teabag for making this project available and user friendly to DIY community.
I am about to begin my build.
For Q4, Q5, Q6 2SK170 I have these values: 6.7/6.8/7.1, 7.7/8.1, 8.40/8.44, 9.05/9.05, 9.10/9.16, 9.28/9.34. 9.4/9.4, 9.95/9.95, 10.17/10.20, 10.37/10.37, 10.4/10.47/10.5. Which three pairs do you want me to choose ? I am familiar with very helpful Teabag chart R8/R11 vs IDSS.
How tight should be IRF9610 and IRF530 matched ?
Anybody got tips on soldering SMD resistors on the PCB ?
Thank you, Michael
First I want to thank you and Teabag for making this project available and user friendly to DIY community.
I am about to begin my build.
For Q4, Q5, Q6 2SK170 I have these values: 6.7/6.8/7.1, 7.7/8.1, 8.40/8.44, 9.05/9.05, 9.10/9.16, 9.28/9.34. 9.4/9.4, 9.95/9.95, 10.17/10.20, 10.37/10.37, 10.4/10.47/10.5. Which three pairs do you want me to choose ? I am familiar with very helpful Teabag chart R8/R11 vs IDSS.
How tight should be IRF9610 and IRF530 matched ?
Anybody got tips on soldering SMD resistors on the PCB ?
Thank you, Michael
I also got delivery of Tea-Bag GB goodies. What a piece of kit! 🙏
My naive question. How can I use two raw PSU, one internal (to use on the small system with MM where shelf space is limited) and one external (to use on the main system with MC cartridges)? This means having both 230 fused AC socket and power DC input on the back panel. But how to connect the DC wiring? Is it a switch necessary or just be careful in connecting one PSU at the time?
My naive question. How can I use two raw PSU, one internal (to use on the small system with MM where shelf space is limited) and one external (to use on the main system with MC cartridges)? This means having both 230 fused AC socket and power DC input on the back panel. But how to connect the DC wiring? Is it a switch necessary or just be careful in connecting one PSU at the time?
Use a toggle switch. DPDT On-On.
Put 22k 0.5W resistors across the +- pins of every reservoir capacitor on both raw supplies.
Those resistors are bleeder (slow discharge) provisions to surely empty a PSU when turned off and unloaded.
Don't switch over raw DC lines live. Wait for five minutes after AC power is turned off for both PSU. Then switch.
Put 22k 0.5W resistors across the +- pins of every reservoir capacitor on both raw supplies.
Those resistors are bleeder (slow discharge) provisions to surely empty a PSU when turned off and unloaded.
Don't switch over raw DC lines live. Wait for five minutes after AC power is turned off for both PSU. Then switch.
I'm preparing the build at the moment, so questions will rise haha...
Does it matter at what voltage you measure the Idds of the 2SK170BL to have them matched? I see some people match transformers with 9V others with 18V, etc... I can imagine it makes a slight difference, does is matter or is it small enough to ignore?
Does it matter at what voltage you measure the Idds of the 2SK170BL to have them matched? I see some people match transformers with 9V others with 18V, etc... I can imagine it makes a slight difference, does is matter or is it small enough to ignore?
Transformers = transistors offcourse.... The 2SK170BL seem quiet hard to be found,
I have bought a few now with the following that have the following Idss on the bags; 7.13-7.14-7.22-7.23-7.63-7.64-7.68-7.71-7.89-7.92-8.21-8.23mA.
I probably can use some of them for sure, but seems i am missing a pair between 8.2 and 8.5mA matched within 1%.
I have bought a few now with the following that have the following Idss on the bags; 7.13-7.14-7.22-7.23-7.63-7.64-7.68-7.71-7.89-7.92-8.21-8.23mA.
I probably can use some of them for sure, but seems i am missing a pair between 8.2 and 8.5mA matched within 1%.
Yes the test voltage matters when you are aiming at a certain tight IDSS bracket if so noted on a schematic. The higher the VDS the bit more IDSS mA you get. Can expand to 1-2mA difference or more between using say 5-15V as it warms up. Dissipation mW is obviously different. Even dangerous if using too high VDS on a high IDSS sample. Especially on upper range BL and 2SK170V.
Datasheet reference is 10V VDS and a 9V battery is still acceptably close. I use a bench supply set at 10V and 50mA CC current limit to avoid mishaps. I don't trust the PSU's mA indication when for few mA. I thread the test rig through a good DMM's mA current measuring loop.
If its strictly for matching between samples you don't really care for the absolute mA figures thus the VDS test voltage is not of primary importance.
Datasheet reference is 10V VDS and a 9V battery is still acceptably close. I use a bench supply set at 10V and 50mA CC current limit to avoid mishaps. I don't trust the PSU's mA indication when for few mA. I thread the test rig through a good DMM's mA current measuring loop.
If its strictly for matching between samples you don't really care for the absolute mA figures thus the VDS test voltage is not of primary importance.
Take some close up pictures and post them so we check if they are at least visually original.
I do have a bench supply, so i can test them on 10V Vds and see if they measure the same as the value thats on the bags now.
I will try to post some closeup pictures of a few this afternoon. I didnt know they were this hard to find, else i would have ordered them together with the PCB's at teabag. I did a quick google search and found quiet some stuff, but most webshops who have them on their site are sold out en others or china for sure.
I will try to post some closeup pictures of a few this afternoon. I didnt know they were this hard to find, else i would have ordered them together with the PCB's at teabag. I did a quick google search and found quiet some stuff, but most webshops who have them on their site are sold out en others or china for sure.
Here are two of the JFETs. After searching how to recognize fakes, it seems i got some fakes... what is the downside of a fake, when Idss measures within the range?
Other question as well: is a VTA56 foil resistor worth investing for the 47k positions? They are 7 euro a piece. Offcourse, not as good as a z201. I was thinking of buying VSH foils, but they are sold out now in the store i was thinking of buying them from.
Other question as well: is a VTA56 foil resistor worth investing for the 47k positions? They are 7 euro a piece. Offcourse, not as good as a z201. I was thinking of buying VSH foils, but they are sold out now in the store i was thinking of buying them from.
-Yes, they look non legit. Fakes of good IDSS may DC bias right but lack in transcoductance and noise. In other words to give lower AC gain along with more hiss than expected for originals in a specific circuit.
-VTA56 bulk foil axial resistor is a worthwhile precision part.
-VTA56 bulk foil axial resistor is a worthwhile precision part.
Thank you for the quick responses every time Salas!
I'm gonna search for some new 2SK170BL. I found some other shops but im guessing most sell fakes.
Does anybody if these are geniune https://jimsaudio.com/2sk170bl-low-noise-n-channel-j-fet-matched-idss-to-0-1ma-1-pair/
They are a bit more expensive, but they are matched an i can perhaps ask him the right range as well. So i dont have to order a bunch and match them myself.
I'm gonna search for some new 2SK170BL. I found some other shops but im guessing most sell fakes.
Does anybody if these are geniune https://jimsaudio.com/2sk170bl-low-noise-n-channel-j-fet-matched-idss-to-0-1ma-1-pair/
They are a bit more expensive, but they are matched an i can perhaps ask him the right range as well. So i dont have to order a bunch and match them myself.
Jimsaudio is often mentioned here at diyaudio as a reliable seller. So is punkydawgs, here: https://www.ebay.com/str/punkydawgs
(I have got myself a matched quad from the latter, but haven’t used it yet.)
(I have got myself a matched quad from the latter, but haven’t used it yet.)
Hi.
I made the Ultra FSP (Tea Bag kit ).
Everything works but there is too much noise, it is much more important than the background noise of the vinyl, and it is incompatible with classical music.
If I replace the UBIB 1.3S power supply by a battery (34V), the noise is ok.
If I replace the UFSP RAW PSU PCB by a battery (38V in -> 32V out) it doesn't change anything.
I can set all voltages correctly from 30 to 34V for the UBIB 1.3S output, and 4V on the Ultra FSP.
I have a Phasemotion MC200 MC cell (4 Ohms 0.3mV).
Can you indicate me some tests to make on the UBIB 1.3S power supply ?
Best Regards.
I made the Ultra FSP (Tea Bag kit ).
Everything works but there is too much noise, it is much more important than the background noise of the vinyl, and it is incompatible with classical music.
If I replace the UBIB 1.3S power supply by a battery (34V), the noise is ok.
If I replace the UFSP RAW PSU PCB by a battery (38V in -> 32V out) it doesn't change anything.
I can set all voltages correctly from 30 to 34V for the UBIB 1.3S output, and 4V on the Ultra FSP.
I have a Phasemotion MC200 MC cell (4 Ohms 0.3mV).
Can you indicate me some tests to make on the UBIB 1.3S power supply ?
Best Regards.