I had these film caps laying around already from an ancient audio boneyard. They measured well, so I used them, I did not order them recently.
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This is how I'm driving my board, it works great. No changes needed, just build according to the instructions for the regulator. A 20R power resistor produces about 147mA of current. I used 4 green LEDs, 2 red ones, and put a jumper in for the diode. I think I used a 10k pot. The input to the board is from a 24v 2A linear wall wart that provides about 30v without a load and about 28.5v when connected to the BiB regulator.
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Noted on the magnets and great idea on the surgical gel. I am actually thinking of the 3M industrial double sided tape but as a absorbent, so I will only let the NuTube rest on it.
This is how I placed the gel. It can be removed and replaced with ease.
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For anyone who's interested, here is a Mouser project parts list for the Korg-NuTube-DIY-V1R0 board. Changes from Papa's latest DIY parts list are Vishay CMF-series resistors (substitute for SFR), Kemet EST-series power supply caps (10K hours rated) and Mean Well power supply. I used an Alps "blue velvet" 50K audio taper pot from Parts Express on the "Xmas" build and it sounded very good. Other parts on that build were Rean NYS367 isolated RCA jacks from Mouser and a "Select 2" input switch from Glassware Audio wired to switch both hots and grounds. I am curious to see if I can hear a difference between the "Xmas" Toshiba and the DIY store Fairchild JFETS.
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The currently available DIY audio store boards. Build guide notes here:
http://www.firstwatt.com/pdf/art_diy_nutube_preamp.pdf
Thanks Eric,
Do you have a part number for the wall wart you're using? I had planned on using a donut and diodes, but the wall wart sounds interesting. I had assumed most/all wall warts were switch mode. Any advantage/disadvantage to the wall wart?
You're not using the sense wires. I was thinking of skipping that as well.
I haven't built a BIB shunt reg in a couple years, the board I have was left over another project and Tea had some parts kits left over. I need to do some rereading...My memory is shot, I can't remember how I put that thing together.
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I don't, so I went back the MPJA website to see if I could find it, but it appears they are no longer in stock. It has a cord that plugs into the AC socket, an enclosed transformer (plus diode/cap) in the middle of the cord, and a 5.5/2.1mm plug at the other end. It is rated at 24v 2A and cost me about $12. I think it was a "clearance" item when I picked it up a few months ago. While there were ones with lower output current, I chose the higher rating figuring it would way overshoot the 24v mark, thus giving the regulator some headroom to work well. This turned out to be true as its unloaded voltage is just about 30v.
I'm not using the sense wires right now, I was thinking I'd probably hook them up "properly" in the finalized chassis. Still waiting for a few parts to arrive...
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Found it! It's at jameco, not mpja...
EHU240200: Jameco Reliapro : 24V 2A 48W AC-to-DC Unregulated Linear Table-Top Power Supply : Power Supplies & Wall Adapters
EHU240200: Jameco Reliapro : 24V 2A 48W AC-to-DC Unregulated Linear Table-Top Power Supply : Power Supplies & Wall Adapters
This power supply is not regulated. Reading NP's article it is important to have a regulated PS to insure 24V's no matter the AC voltage variances.
"The preamp can be made to work with other supply voltages, but you will find yourself adjusting resistors and also needing a distortion analyzer to set the Nutubes for the desired distortion character. Easier to use 24V. If you use a linear power supply, you will want to have it regulated, as we need a constant DC value regardless of AC line voltage."
This one is regulated for about the same price.
GST25U24-P1J MEAN WELL | Mouser
This is the one NP has listed in the article. WSU240-0500-13 Triad Magnetics | Power Supplies - External/Internal (Off-Board) | DigiKey
It is regulated in the data sheet.
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Browsing through this very interesting thread while waiting for my Korg to arrive... many thanks to all contributors, that project looks really fun.
Having a look at the builts, 6L6 and others, I couldn't help noticing 2 intriguing things. Perhaps one can enlighten me?
1- Cat5 wire seems a popular and interesting choice, good to know. How come on some builts Cat5 is used all the way up until the volume potentiometer, but then coax cable is used from the potentiometer to the board - any reason for that? Perhaps the signal can be so much attenuated that coax is required to shield better the tiny signal? Or just overkill / materials left in the bin when building LOL?
2- Grayhill selectors seems also a nice find. That one seems recommended all along:
56S36-01-2-03N
However, browsing Grayhill on on Mouser I found 2 similar ones, but in the 50 line :
50A60-01-2-03N, for a very close price, admittely 60° throw
50A36-01-2-03N, admittely a bit more expensive but with a 36° throw (does one really need that with 3 poles?)
Now, apart from the seal the 56 seems to have (and that seems a nice add-on only for outdoor use unless I missed something?), that 50 series seems to have even better low resistance contact specs and the solder terminals are a tad friendlier for DIYer.
Could the 56 series be a better choice, or is just the 50 series the one to have for nice sounding applications? I must say a bit confused with all these letters and similar prices, perhaps not comparing appled with apples?
Many thanks for your kind help
Claude
Having a look at the builts, 6L6 and others, I couldn't help noticing 2 intriguing things. Perhaps one can enlighten me?
1- Cat5 wire seems a popular and interesting choice, good to know. How come on some builts Cat5 is used all the way up until the volume potentiometer, but then coax cable is used from the potentiometer to the board - any reason for that? Perhaps the signal can be so much attenuated that coax is required to shield better the tiny signal? Or just overkill / materials left in the bin when building LOL?
2- Grayhill selectors seems also a nice find. That one seems recommended all along:
56S36-01-2-03N
However, browsing Grayhill on on Mouser I found 2 similar ones, but in the 50 line :
50A60-01-2-03N, for a very close price, admittely 60° throw
50A36-01-2-03N, admittely a bit more expensive but with a 36° throw (does one really need that with 3 poles?)
Now, apart from the seal the 56 seems to have (and that seems a nice add-on only for outdoor use unless I missed something?), that 50 series seems to have even better low resistance contact specs and the solder terminals are a tad friendlier for DIYer.
Could the 56 series be a better choice, or is just the 50 series the one to have for nice sounding applications? I must say a bit confused with all these letters and similar prices, perhaps not comparing appled with apples?
Many thanks for your kind help
Claude
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You are correct
. This is why I'm using it with the Salas BiB regulator I posted an image of just a few posts up . The linear supply gives the regulator some voltage headroom to work well.You are correct
Have not followed all of your post but the info may help others. It is imperative to have a regulated voltage of 24V for the circuit to operate as designed.
Eric, I really appreciate your effort. I have one in my Jameco cart now, BUT they want $13.75 for UPS ground shipping, and a $5.00 minimum processing fee...with tax the total comes to $32.48...for a $12.95 part. That's ridiculous!
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Bummer... I ordered a ton of other stuff at the same time (two of these PSUs, some dc power jacks, and a handful of other things). This removed the $5 processing fee for not reaching a minimum order and evened out the shipping charges across a larger number of items that I wanted.... I don't remember if I did UPS delivery or USPS - for vendors that offer both forms of shipping, USPS is often less expensive and faster...
I did, no problem that I am aware of. Can depend on sub amplifier used though.
Or you could use something like this : 2pcs brass RCA Audio Y Splitter Adapter 1 Male to 2 Female Plated connector 601334124068 | eBay