Has somebody build the new Salas 1.3 for the Korg Nutube 0,24+. I have a spare 0-23v 0.5A RCORE readily available with me so presuming that the Salas board needs 0-24v which has a 5v drop, can I get away with a 0-23vac secondary with 0.5A?
I used this DimDim's BOM for my Soekris +/-12Vdc on the Salas 1.3 board. Can I still use the same BOM with the R1 being 3.3R 3W resistor but I think I should change the trimmer and the Vrr values. Can someone point out as I have most of the parts to build this PSU including a 10000uf 35v cap.
thanks
I used this DimDim's BOM for my Soekris +/-12Vdc on the Salas 1.3 board. Can I still use the same BOM with the R1 being 3.3R 3W resistor but I think I should change the trimmer and the Vrr values. Can someone point out as I have most of the parts to build this PSU including a 10000uf 35v cap.
thanks
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Manniraj. I made mine with 50VA- sec23V transformer and UltraBiB. I chose 3R3 for R1 and that gives plenty mA to spare.
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That's been brought up before. Yes, the board is correct. Both ways
work, and the board layout is very slightly quieter.
Plate Resistor Values
In the original micro article Nelson published in the first post here, he mentions that he had tried a lower value plate resistor initially, but raised it to meet his goal for the preamp's gain. I'm building my B1Korg, primarily, to front a MOFO that will drive my 95db speakers. Is it worthwhile to go back to that 332k resistor value, and will it bias properly without other resistor changes? To add a bit more context, I have a couple of Magnequest autoformers that could be used after the preamp to double the voltage swing to the amp. It looks like the units could handle this from an impedance standpoint
Thanks, Skip
In the original micro article Nelson published in the first post here, he mentions that he had tried a lower value plate resistor initially, but raised it to meet his goal for the preamp's gain. I'm building my B1Korg, primarily, to front a MOFO that will drive my 95db speakers. Is it worthwhile to go back to that 332k resistor value, and will it bias properly without other resistor changes? To add a bit more context, I have a couple of Magnequest autoformers that could be used after the preamp to double the voltage swing to the amp. It looks like the units could handle this from an impedance standpoint
Thanks, Skip
Yes keep 332K plate resistors 🙂 this value choice was made by Mr. Pass because H2 second harmonic distortion
have nice pure sine wave form and negative phase if You adjust adequate voltage on the output jfets buffer point T7 , T8
on the pcb and reverse speakers outputs on the power amplifier for respect of the absolute phase.
B1 Triode jfet buffers Idss = 3 to 8 mA.
Some 2SK170 GR can be OK as well after test 🙂
So to be specific anything over 8 mA is unusable or some tweaking reuired in the circuit?
GR grade are much more difficult to procure.
I have a GB going for BL grade. Punkydawgs says about roughly about 70% come in at 7-9mA's.
Idss of 2SK170 BL ( blue) is start from 6 and end on 12 mA 🙂
B1 Triode is perfect preamp for the amplifiers with 20 dB of gain.
MoFo is one power stage without gain.
Build one 20dB front end ( with transistors ? ) for the MoFo are B1Triode good companion at the signal inputs 🙂
Korg have ~ 16 dB of gain but distortion raise very very quickly so better keep them low that is the reason
for use of the great front end with.
B1 Triode is perfect preamp for the amplifiers with 20 dB of gain.
MoFo is one power stage without gain.
Build one 20dB front end ( with transistors ? ) for the MoFo are B1Triode good companion at the signal inputs 🙂
Korg have ~ 16 dB of gain but distortion raise very very quickly so better keep them low that is the reason
for use of the great front end with.
From the popular amplifiers in the forum, what would be the one that works fine gain-wise with the Korg with no modifications at all? M2x?
Yes I am aware of the full range of the BL grade transistors. The Question remains is anything over 8 mA's Idss usable in this particular circuit? I'm about to purchase 200 BL's and match them and send them to members on a group buy. Just checking if the higher range say 9 or 10 mA's will be ok to use.
in post #121 Zen Mod suggests 2sk170BL. This is where I got the idea. Maybe Zen Mod or Mr. Pass could weigh in with an answer.
I was in doubt if I said somthing on the GB or not...
Pass says (post link) : Best to check the bias voltage. Korg warns that if the filament is red then it's too high. This is regulated by the 9,1V zener, so check that as well.
I have been using Toshiba Jfets Idss 3 to 5 mA, work just fine. Fairchild J113 parts about 8 mA Idss.
Source resistor for the DIY board current source is for setting high Idss Jfets to lower value.
Plans are that the kit will have the Fairchilds with the appropriate Source resistor values, typically 100 to 221 ohms.
People with matched parts and also Idss at 8 mA or less can short the Source to Ground on the current source Jfet.
Pass says (post link) : Best to check the bias voltage. Korg warns that if the filament is red then it's too high. This is regulated by the 9,1V zener, so check that as well.
I have been using Toshiba Jfets Idss 3 to 5 mA, work just fine. Fairchild J113 parts about 8 mA Idss.
Source resistor for the DIY board current source is for setting high Idss Jfets to lower value.
Plans are that the kit will have the Fairchilds with the appropriate Source resistor values, typically 100 to 221 ohms.
People with matched parts and also Idss at 8 mA or less can short the Source to Ground on the current source Jfet.
Sounds like this B1Triode can be a good match for the 50W Schade Enabled amp which has 20db of gain?
The B1 Triode works wonderfully with the F5, M2x and ACA so I would guess it would be a perfect match with an Aleph J.