Nobelium - tube bass preamp project

Hey guys - for those daunted by the build - its really not that hard.

I made a video tutorial of the complete Nobelium build. I though I'd share it if anyone was thinking of building their own. While it is not a beginner build, it's really not that difficult if you take your time.

It is a long video, and designed for you to build yours along with me.
Enjoy!

(This in NOT a paid promotion or endorsement - it was just a fun project, especially if you cannot affort/wait for a Noble).

 
alaistair said:
Hey guys - for those daunted by the build - its really not that hard.

I made a video tutorial of the complete Nobelium build. I though I'd share it if anyone was thinking of building their own. While it is not a beginner build, it's really not that difficult if you take your time.

It is a long video, and designed for you to build yours along with me.
Enjoy!

(This in NOT a paid promotion or endorsement - it was just a fun project, especially if you cannot affort/wait for a Noble).

Click to expand...
Fantastic video. Thank you. Bonus point for the beautiful Scottish accent.
 
chongmagic said:
Can I use a 390pf silver mica in place of the 270p?
Click to expand...
Since I can't sleep again I ran it through TSC, not much difference between the two.
The Mid pot stays on full since it is just a resistor in the Nobelium.

Standard Tonestack: https://www.guitarscience.net/tsc/f...C3=100n&RB_pot=LogA&RM_pot=Linear&RT_pot=LogA

390Pf in tonestack: https://www.guitarscience.net/tsc/f...C3=100n&RB_pot=LogA&RM_pot=Linear&RT_pot=LogA

I ran a sweep but it is not completely correct since the Mid should not sweep, 390pF seems to just affect the dip at around 250Hz to 400Hz, the 390pF just dropped the mid dip and Treble by about 40 Hz.
 

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Hi,
I just finished my Nobelium build (from Musikding in Germany) yesterday. Unfortunately I'm not getting any sound at all. Neither through the di or the amp out.
Both LEDs light up, I can measure ground all the way through, the connection is fine between input jack and in on the PCB. Both tubes heat up as well - no more than they're easy to touch.
The soldering looks quite fine, but does anyone have some indications as to what and where I could measure?
Thanks
 
itchymusic said:
Hi,
I just finished my Nobelium build (from Musikding in Germany) yesterday. Unfortunately I'm not getting any sound at all. Neither through the di or the amp out.
Both LEDs light up, I can measure ground all the way through, the connection is fine between input jack and in on the PCB. Both tubes heat up as well - no more than they're easy to touch.
The soldering looks quite fine, but does anyone have some indications as to what and where I could measure?
Thanks
Click to expand...
It may be beneficial to start your own debugging thread with pictures of your build.
 
matmonster58 said:
anyone know where i can buy a jensen JT-DB-EPC? A few places have the wirelead version but not the pcb mount version
Click to expand...
Back when I was auditioning transformers the only place I was able to find them was direct from Jensen, and I had to reach out to a sales rep and get a quote and stuff.

Aliexpress seems to have a knockoff JT-DB-EPC for $17, I'll have to grab one to try out.
 
I would wait for the C2CE Unagi one to come back in stock but if you must have a Jensen try here:\
EDIT: Never mind, it looks like they are sold out.
store.generalguitargadgets.com

JENSEN JD-DB-EPC TRANSFORMER

This is the coveted Jensen transformer for Direct Boxes. Best know as used in the Radial JDI Direct Box. Simple to use and one of the best, if not the best transformer to use for passive or active direct boxes (guitar signal to XLR jack for input to a console or PA system). This is the PCB Mount...
store.generalguitargadgets.com
 
Last edited:
Tassieviking said:
I would wait for the C2CE Unagi one to come back in stock but if you must have a Jensen try here:\
EDIT: Never mind, it looks like they are sold out.
store.generalguitargadgets.com

JENSEN JD-DB-EPC TRANSFORMER

This is the coveted Jensen transformer for Direct Boxes. Best know as used in the Radial JDI Direct Box. Simple to use and one of the best, if not the best transformer to use for passive or active direct boxes (guitar signal to XLR jack for input to a console or PA system). This is the PCB Mount...
store.generalguitargadgets.com
Click to expand...
The Unagi should hopefully be back in early April. I thought I had plenty on hand to last until then, but Sushi Box production shares transformer stock with C2CE, and with a new run of Neptunium the transformers quickly started disappearing. The last few orders only took 6 weeks to build, but this is a bigger order and went straight to 10 weeks.
 
matmonster58 said:
anyone know where i can buy a jensen JT-DB-EPC? A few places have the wirelead version but not the pcb mount version
Click to expand...
Cable solutions stocks the Jensen and also the equivalent Cinemag. They do run out of stock because the way Jensen manufacturers.

CS will put in an order for X amount of the transformers. Jensen batches that order with others and runs a production line for that specific part to fill the orders. Once that is done, Jensen uses the line for another product. Cycle repeats. It appears that CS doesn't put another order in until they either run out of stock, or it gets too low to bridge the next order.

Stock of the Jensen transformer usually runs out first before the Cinemag does. Check the Cinemag datasheet as I believe those are pin for pin including spacing equivalents.

The other option is to go on Ebay and buy a used Radial with the JT-DB-EPC in it. You can find them cheaper than buying new at CS and other places. You will need to desolder though.

I have several JT-DB-EPC and a Unagi. Physical inspection clearly shows the Jensen to be better quality, but it is $30 less. Sound-wise, the Jensen is better, but YMMV since your ears are not mine.

I've used Cinemag, but long ago to where I cannot comment on comparison. I've never used Lundahl or Lightning Boy. So I cannot comment on those.

For Vigilante: I been looking occasionally for the Unagi datasheet to be uploaded to CSC. I would rather use the datasheet for my design rather than mic up the XLR board I have. If you could uploaded, I would appreciate it.
 
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I have a LBA in my personal build and have a unagi in hand for slan up coming project.

I'm building a nobelium for a friend who is insistent on using a Jensen transformer
 
Looks like Cable solutions has one and it's now on the way.

If I have time I'll try to do a shoot out with the three.

I can reamp from my interface and turn the XLR output all the way up so the transformer is getting hit hard. If the differences are great enough I might be able to isolate them with a null test.
 
matmonster58 said:
anyone know where i can buy a jensen JT-DB-EPC? A few places have the wirelead version but not the pcb mount version
Click to expand...
Radial responded to me a while ago they’d sell direct. Price was basically same as other outlets online once currency conversion was done (those were USA only, and this was before all of this tariff stuff happening, but there was still issue of what duty would be). Also, this is in Canada.

Radial Engineering

Radial Engineering Ltd. is a manufacturer of professional audio products based in Vancouver, British Columbia, Canada. A longstanding reputation for bringing reliable and tough-as-nails problem solvers to the market means you will see Radial products on stages and in studios world-wide.
www.radialeng.com www.radialeng.com
 
Well CS doesn't have one and won't be restocking it seems because tarrifs and such. They do have the cinemag equivalent though.

I've contacted Jensen directly and haven't heard back. I'll try radial
 
Cable Solutions is in Richmond, Texas and Jensen Transformers facility is located in Chatsworth, California where they manufacture. There are no tariffs between states. So I don't understand what you've heard. I've successfully added a JT-DB-EPC to the shopping cart on their website tonight. I didn't buy it because I've received several from CS a week ago. Return address was Richmond, Texas on the shipping label.

When CS' stock is out, it usually takes a couple of months before they get another shipment from Jensen.

Jensen Speakers is not the same company as the transformers in case that is causing confusion. Jensen Speakers is no more for some time now, and an Italian company is making drivers under that Jensen trademark.
 
I was able to check out a JT-DB-EPC at CS but received an email a few days later stating that they don't have any and don't know if they will be getting more because these transformers are now manufactured in Canada.
 
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