I completed the build today and adjusted UBiB to 34V, but phono T.P reading is 7.9V and turning it's VR1 doesn't change much.
Probably went wrong somewhere, any hints what to look for?
Probably went wrong somewhere, any hints what to look for?
Did you configure the gain of choice on the DIP switches first? Needs that step also to respond.
Tribute,
I used 2 of these from Element 14.
https://au.element14.com/vigortronix/vtx-146-050-215/50va-toroidal-transformer-2x15v/dp/2817652
Worked perfectly for me.
I used 2 of these from Element 14.
https://au.element14.com/vigortronix/vtx-146-050-215/50va-toroidal-transformer-2x15v/dp/2817652
Worked perfectly for me.
Yes, S8 ON S12 ON all others OFF (downwards position).
I use Linn K18 MM cartridge, so 2SK369BL matched Pair (Q1) with resistors at R2.
Should I try some other setting and see if voltage changes?
In UFSP you need everything installed, not only Q1 R2, but Q2 R3 too. Q2 alone actually does all modes other than LMC. So have it completed first.
Go down to 32V rail also and try again. MM mode usually demands less than 34V which is a general starting point.
If nothing changes, verify the switches are actually going on/off as expected by using the DMM's continuity buzzer on their pins across. On means a short. Do that with the power off. Verify the resistor values they connect to as well.
Go down to 32V rail also and try again. MM mode usually demands less than 34V which is a general starting point.
If nothing changes, verify the switches are actually going on/off as expected by using the DMM's continuity buzzer on their pins across. On means a short. Do that with the power off. Verify the resistor values they connect to as well.
Yes, using 15+15V easy to find transformer types with their secondaries connected in series for 30V nominal is perfectly legit. Those have 230V primary spec so giving out bit more in 240V tending New Zealand & Australia.
I wouldn't recommend that EI you linked. Will surely radiate more magnetic field than a good toroidal. Do as ZUM911. His pick looks much better and little cheaper even.
Thanks, better now. When I dialed down to 32V I got 4,23V on phono while it's pot was trimmed totally down. To get exactly 4V on phono, the UBiB had to be on 31.2V and another on 31.4V.
Is that OK to proceed?
Yes its within logical range for MM mode and OK to proceed. Remember, the other modes will likely ask for higher rail than that. When changing gain mode you set it up on the switches first with power off. Then you readjust T.P for that new mode.
Thanks, fired it up. Got only slight hum, but no audio. Will investigate later, night hours approaching.
Post a picture of the build if possible tomorrow so we can take a look for finding something odd too.
Both main boards miss a bunch of crucial parts. No Q4,Q5,Q6 no R8,R11. There is no second gain stage and no output buffer stage there in other words.
Thanks, clear now. My bad as misunderstood the group buy. Thought I should choose between 2SK369BL or 2SK170BL and didn't order the latter.
I hope Tea-Bag can help me out with missing parts.
I hope Tea-Bag can help me out with missing parts.
Jfet Confussion
Ok Folks,
Just trying to figure the Jfet requirements so I can purchase the correct types and amounts.
Looking at the schematic there is a "2SK369KBL" at Q1 and Q2.
Looking at the Schematic there is a "2SK170BL" at Q4, Q5, and Q6.
I assume all "6" positions are required to be populated with the respective part.
I do have a Technics turntable "SL-BD20D" something very cheap I got about 15 years ago. Don't know what kind of cartridge there is installed. "Cheap" I will upgrade to a new turntable and cartridge very soon. I can afford a Technics Sl-1210GR but can I justify it. Or can I just beg for forgivness from the wife, cause "She" ain't gonna give me permission.
If I had to guess, about a $700 to $800 dollar table and $200 to $300 cartridge. Moving Magnet.
What confuses me is the "2SK369BL".
Do I get the Matched QUAD, I do need "4" of them correct?
I think the "Triple Pair of 2SK170BL" is required, correct? A total of "6"
Still confused about the Matched Pair of "2SK369BL" Would have to order "2" of the matched pairs????
What is the difference between the Matched Pairs and Matched Quads 2SK369BL
What all of the questions above mean is Just tell me what I need. I am an Old Redneck from Louisiana, sure ain't an electronics sort of guy but I can follow directions. Thanks Folks!!!
Listening to The Allman Brothers on My F5 and Waynes 2018 Linestage fed from a Raspberry Pi with an Allo Boss. Time for another Beer.
Ok Folks,
Just trying to figure the Jfet requirements so I can purchase the correct types and amounts.
Looking at the schematic there is a "2SK369KBL" at Q1 and Q2.
Looking at the Schematic there is a "2SK170BL" at Q4, Q5, and Q6.
I assume all "6" positions are required to be populated with the respective part.
I do have a Technics turntable "SL-BD20D" something very cheap I got about 15 years ago. Don't know what kind of cartridge there is installed. "Cheap" I will upgrade to a new turntable and cartridge very soon. I can afford a Technics Sl-1210GR but can I justify it. Or can I just beg for forgivness from the wife, cause "She" ain't gonna give me permission.
If I had to guess, about a $700 to $800 dollar table and $200 to $300 cartridge. Moving Magnet.
What confuses me is the "2SK369BL".
Do I get the Matched QUAD, I do need "4" of them correct?
I think the "Triple Pair of 2SK170BL" is required, correct? A total of "6"
Still confused about the Matched Pair of "2SK369BL" Would have to order "2" of the matched pairs????
What is the difference between the Matched Pairs and Matched Quads 2SK369BL
What all of the questions above mean is Just tell me what I need. I am an Old Redneck from Louisiana, sure ain't an electronics sort of guy but I can follow directions. Thanks Folks!!!
Listening to The Allman Brothers on My F5 and Waynes 2018 Linestage fed from a Raspberry Pi with an Allo Boss. Time for another Beer.
Q1 Q2 are central parts of the input stage. There where the gain modes configurations take place.
To have all gain modes available you need to install matched quad 2SK369BL (Q1 Q2 per channel i.e. 4pcs).
You can not have the 62dB LowMC gain mode without all four of them 369s in place. But there is also life before quad.
With just a matched pair (only Q2 per channel i.e. 2pcs) you can have 40dB MM 43dB HighMC 56dB RegularMC modes.
All mentioned gain modes are configurable with the DIP switches. No PCB rework is needed to change gain.
Every 2SK170BL position must be populated. They make the rest of the circuit stages which are the same for any gain mode.
About the SL-BD20D there is good opinion in its category and some P-Mount cartridge info & recommendations in Vinyl Engine
Such cartridges are MM but some not too strong 2.5-3.5mV so the 43dB gain mode can also be tested if any better with them.
There are interesting JICO stylus equipped pricier AT92 based P-Mount cartridges with Shibata & Line contact which can lift the sound quality beyond imagined for your now TT. The line contact model has a better cantilever too.
To have all gain modes available you need to install matched quad 2SK369BL (Q1 Q2 per channel i.e. 4pcs).
You can not have the 62dB LowMC gain mode without all four of them 369s in place. But there is also life before quad.
With just a matched pair (only Q2 per channel i.e. 2pcs) you can have 40dB MM 43dB HighMC 56dB RegularMC modes.
All mentioned gain modes are configurable with the DIP switches. No PCB rework is needed to change gain.
Every 2SK170BL position must be populated. They make the rest of the circuit stages which are the same for any gain mode.
About the SL-BD20D there is good opinion in its category and some P-Mount cartridge info & recommendations in Vinyl Engine
Such cartridges are MM but some not too strong 2.5-3.5mV so the 43dB gain mode can also be tested if any better with them.
There are interesting JICO stylus equipped pricier AT92 based P-Mount cartridges with Shibata & Line contact which can lift the sound quality beyond imagined for your now TT. The line contact model has a better cantilever too.
Is it correct to say that Q1/Q2 have a positive temperature coefficient with regard to resistance and the bias current (and TP voltage reading) will decrease as the jfets warm? A second related question: Is the bias most sensitive to temperature variation at the highest gain (~62dB) setting? I think the answer is "yes" based on the low series bias resistor values?
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