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GB B1 Nutube PCB with integrated PS
GB B1 Nutube PCB with integrated PS
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Old 18th March 2019, 09:52 PM   #131
Algar_emi is offline Algar_emi  Canada
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GB B1 Nutube PCB with integrated PS
Tried at the post office, but there was a long waiting line, with apparently special cases at the counter... Will get back tomorrow. Stay tuned...
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Old 18th March 2019, 11:26 PM   #132
Algar_emi is offline Algar_emi  Canada
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GB B1 Nutube PCB with integrated PS
Still a few extra pcb available, I had to order slightly more to get the number of requested pcb. Send me an email if interested, I won't do an other GB of the pcb, so this is your chance. Thanks
SB
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Old 19th March 2019, 02:55 PM   #133
Algar_emi is offline Algar_emi  Canada
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GB B1 Nutube PCB with integrated PS
Hi. Sending Shipping cost payment request right now, please check your email. I'll re-send the latest doc, and PCB correction doc with the shipping payment request.
Thanks
SB
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Old 19th March 2019, 03:24 PM   #134
Algar_emi is offline Algar_emi  Canada
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GB B1 Nutube PCB with integrated PS
Hi. Shipping payments are already getting in. I'll start shipping this afternoon, count 5-10 days for most countries for delivery. Please let me know when you get it.
Thanks
SB
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Old 19th March 2019, 05:35 PM   #135
Algar_emi is offline Algar_emi  Canada
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GB B1 Nutube PCB with integrated PS
Some asked for an assembly guide. I was planning to do one, but here a quick starter:

Hi. Not really, but I can help you with a quick guide:

SUPPLY________________________________

1) First solder the smaller smd parts near the SMPS module, starting with the larger smd cap C3, then the inductor L1, then C1 and C2. Check there is no short between V+ and V- pins of the SMPS module

2) install the AC side parts before the SMPS module. Make sure to use a fuse for testing. I used 1A FB...

3) Install the SMPS module, plug the pcb into AC line and insure there is a stable +24V at the 24V/GND TP, mine read 23.92V. Disconnect AC and let discharge the caps. Note: If you don't want to use the builtin SPMS power supply, you can still use an external 24V supply, in this case connect it to the 24V/GND Test point...

4) Install the 3W resistors, slightly elevated from the PCB.

5) Install the rest of the supply section, C4-C10 and both 9.1V zener

6) Re-connect to AC line, insure there is about 24V at ''F'' test point (just over the tube), and +9V at the zener cathode.

PREAMPS SECTION____________________________

7) For the preamp section, solder all the resistors and trimmers.

NOTE: Rled, value not specified because it depends on the led used (color) and the intensity you want. Can be from a few Kohms to up to 30-47K if using a blue led, test it and select accordingly...

8) Solder remaining caps. Take care around C203, incorrect silkscreen. Also add the small missing link between R203 and R208, see PCB correction doc.

9) Connect supply again, and make sure the supply is still ok, and there is no short, disconnect supply and let discharge...

10) Install the K170GR JFET. They need to be match 4-5ma IDSS by pairs, ideally the same IDSS range for all JFET... The J113 need a resistor, J-R1 on the PCB. I haven't tried the J113 option, so can't help you there...
Install ONLY the K170 OR the J113, not both at the same time...

11) Once the JFET are in place, power-on and check the various DC voltages according to the schematic I sent you. The first section of the buffer (Input Q100/101, Q200/201) works fine without the Nutube installed. The stage after the Nutube needs the tube to complete the circuit, but you can still insure there are voltages and no short...

12) Let the supply discharge, and finally install the Nutube. Check voltages according to the schematic. Volatges around the Nutube depends on the trimmer setting, see below. The tube Gain and THD and bias point depend on the trimmer adjustment. You need at least a scope to get the best adjustement (nicer output waveform), and really some THD analyzer (sound card, etc) to be able to null out the best THD level...
Also there is a possibility that both sides of the tube are not exactly the same, so you can probably expect some difference between channel volt readings

Take note that the JFET Buffer sections, have no gain (Gain of about 1), and that the gain comes from the Nutube.

13) If everything is ok with the preamp circuit, you can mount it into an enclosure, connect the input selection switch, and the option of two separate single volume pot, or one dual pot. Keep in mind that you can have a slight difference in gain between each channel, so the option of the two single volume pot can be use to compensate for that. You can always compensate for the difference in gain with the trimmer, to some extend...

Note: the inputs pads were designed to accomodate small PCB Turret, Harwin (Mouser 855-H2121-01) or simply solder your wire.
These turrets insure strong, reliable wire connection, that you can unsolder countless time without damaging the PCB.
If you want to use the turret, as I did, you can install them like that:

1) Install the turrer upside down into a small vise,
2) place the PCB over the turret end, then
3) using a small punch and hammer, and (gently...) punch the turret end in place, repeat until you have a strong connection.
4) repeat for the other location. BTW these turrets can also be installed on the 24V/GND TP location
5) for better result solder the turret from top and bottom.

14) Install the In/out connector, front power-on led and pots, and make a final check.

I did a very detailled schematic with reference voltages everywhere. It is your primary tool to check/test the pcb. Please don't forget to have a look at it

ASSEMBLY COMPLETED...

Last edited by Algar_emi; 19th March 2019 at 05:50 PM.
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Old 19th March 2019, 09:01 PM   #136
Algar_emi is offline Algar_emi  Canada
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GB B1 Nutube PCB with integrated PS
And I should add to connect the AC inlet ground connection to the frame, see first picture, at least in North America.
Safety ground may be different in you country...

To complete my little assembly guide, here picture of my won preamp, missing a few RCA connectors on the back, but you get the idea

Check my little ventilation window on top, we can see the tube looking at you

BTW I used a 22K resistor for Rled, with a red led...

SB
Attached Images
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File Type: jpg IMG_20190319_155301.jpg (79.1 KB, 204 views)
File Type: jpg IMG_20190319_165402.jpg (97.4 KB, 184 views)
File Type: jpg IMG_20190319_165431.jpg (111.0 KB, 114 views)
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Old 20th March 2019, 01:27 AM   #137
GASCo is offline GASCo  United States
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GB B1 Nutube PCB with integrated PS
I like the top window! What is the screen you used?
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Old 20th March 2019, 11:46 AM   #138
Algar_emi is offline Algar_emi  Canada
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GB B1 Nutube PCB with integrated PS
It is from a Polaroid ultrasonic range sensor (from the 80's), now used with robots, see: Ultrasonic Sensors, Piezoelectric Ultrasonic Sensors | SensComp

I got mine from a defective one. I have my own little stach of it

Last edited by Algar_emi; 20th March 2019 at 11:49 AM.
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Old 20th March 2019, 07:17 PM   #139
Praudio is offline Praudio
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Quote:
Originally Posted by Leeuwarden View Post
So how does it sound?
So good ! I am speechless
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Praudio
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Old 20th March 2019, 08:04 PM   #140
Algar_emi is offline Algar_emi  Canada
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GB B1 Nutube PCB with integrated PS
You asked for it, here guys, the first to listen to it, my friend Praudio got mine, just fresh from my bench, and he got a very good hear, and very revealing sound system. He likes it a lot. So we can say that this little preamp is a killer Sound Great
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