Official Universal Passive Tube PSU Thread

[Trickyricky]

Did you ever figure out this problem? I’m having this same issue with mine, everything was great with the 68k resistors in, but I decided to go with a 12at7 tube. So I popped in the recommended 33k resistors and now can’t get the B+ below 135.

Nvm, I think I'm sorted. I installed a test tube and the original badaxx capsule and plugged it into the psu. I was then able to dial in 120v on the B+ and 6.3V on the heater. I'm assuming you need a different value resistor to check mic load with a 12AT7 tube? I will report back once I install my premium capsule and tube.

 

[Purplenoise]

Hey guys. Is it a good idea to use this psu to get 60v B+ by changing the two 68k resistors? Which would be a value you would recommend for those resistors in this case?
Or is it better to go with a different power transformer? Any recommendations for this case?
Thanks in advance.

 

[rock soderstrom]

Hey guys. Is it a good idea to use this psu to get 60v B+ by changing the two 68k resistors? Which would be a value you would recommend for those resistors in this case?
Or is it better to go with a different power transformer? Any recommendations for this case?
Thanks in advance.

Is there a schematic for this PSU?

 

[Purplenoise]

Is there a schematic for this PSU?

No idea,

 

[rock soderstrom]

No idea,

Ok. It would make it easier to answer the question. Especially for people who have not built this PSU yet.

 

[Delta Sigma]

Is this the same PSU as the Matador/Chunger C12 power supply?

If so, it would be this one:
http://musicalsparks.com/images/c12/c12_schematics_v3.pdf
Or this one:
http://musicalsparks.com/images/c12/c12_schematics_1v4.pdf
Found them in this thread:
https://groupdiy.com/threads/official-c12-clone-build-and-support-thread.51377/

 

[C12VR]

Hi I've been able to get B+ and heater voltages right but my bias is stuck at 0. I discovered that I put the trimpot in the wrong way round but shouldn't it still work? Using it for a C12 right now.

 

[tylr]

Hey there! Just got my PCBs for a bunch of mic builds and they're gorgeous! I am building this from scratch with my own chassis that are the Neumann lunchbox style. I have every single thing I need to do the mic build...except the PSU transformers.

Are there any known alternatives to this transformer? Struggling to find anything with dual secondaries at 200v + 9.5v.

 

[johnchantler]

Try and find somewhere that can do a custom transformer like toroidy.pl — maybe there is a more local option for you.

 

[Roman Beilharz]

Hey there! Just got my PCBs for a bunch of mic builds and they're gorgeous! I am building this from scratch with my own chassis that are the Neumann lunchbox style. I have every single thing I need to do the mic build...except the PSU transformers.

Are there any known alternatives to this transformer? Struggling to find anything with dual secondaries at 200v + 9.5v.

Lucky guy! I have ordered my PCBs weeks ago and didn't even recieve a single email about when to expect the shipment from Chunger .

Meanwhile this toroid is sitting on my shelve
G-Pultec Power Transformer - Pri.: 2x115v- Sec.: 220v, 9v and 5v, 53,

and waits to see, whether I could match my voltages with it. As the sec for B+ here is 220V, I guess I will have to use higher drop resistors for R1/2. But then again, my EF86 build needs a bit more Amps, so the standard 68k might be a good starting point. GDIY user Neutrino has obviously used a similar transformer with success, so it should work.

I take the additional - but to most probably superflous - 5V rail as a nice goodie to power my rear capsule diaphragm relay switching instead of tapping H+. I plan to reuse the donor PSU diodes and regulator for this path.

P.S.: If you fight with toroids, never forget your shield:
Trafo shielding sheet, 14,90 €

P.S.S.: This bracket came in handy to mount that thing:
Mounting Bracket for Toroidal Transformer Ø75mm - Audiophonics

They also provide you with toroids generating the necessary secondary voltages, but I couldn't find one taking 2x115v primaries for US and international/universal use and didn't want to add geo restrictions to my PSU.

 

[tylr]

Thanks for the tips John and Roman. I had read the custom toroidal was an option. Was hoping someone found an alternative.

I don’t mind if I need to change the resistors if I can find something in the ballpark but I haven’t had any luck.

I have an Upton 251 I was gonna pop open the chassis and see if that gives me any clues. I believe that PSU is compatible.

I could also just buy an Alctron PSU since they’re probably cheap but wanted to try and find a quality transformer

 

[Matador]

If you are using the stock Alctron case, finding a small enough transformer can be a challenge, because you need dual secondaries (the 200VAC one and 9.5VAC), and it has to be quite small to fit in the stock case.

If you are doing a larger case, there are more options. My favorite is the Antek 50VA 120VAC secondary, and you can wire the dual 6.3V heater secondaries in series to make a 12.6VAC secondary.

https://www.antekinc.com/as-05t120-50va-120v-transformer/

 

[tylr]

If you are using the stock Alctron case, finding a small enough transformer can be a challenge, because you need dual secondaries (the 200VAC one and 9.5VAC), and it has to be quite small to fit in the stock case.

If you are doing a larger case, there are more options. My favorite is the Antek 50VA 120VAC secondary, and you can wire the dual 6.3V heater secondaries in series to make a 12.6VAC secondary.

https://www.antekinc.com/as-05t120-50va-120v-transformer/

Thanks Matador! I am using a much larger chassis so that'll work! I'm ordering a few now.

I was literally just laying out the heater side of the schematic in kicad so I can simulate altering secondary voltages.

 

[Roman Beilharz]

I am sorry to bug y'all with this, but I had ordered and paid my universal PSU PCBs at chunger's studio939 website a month ago and have not recieved a single reply to any of my 3 direct mails/PM via GroupDIY by chunger on when to expect the shipment - forget about the PCBs itself. Is this the normal procedure with this business model, that you have to stay put and wait for weeks/months (?) until Chunger get's his act together and eventually drops a parcel or two?

If this is so, I can not recommend this business to any of the newbies in the forum - even if Matachung's projects/products are great, have all my sympathy and the build guides are amazing.

 

[mrgrooves666]

Yes, it is. However Im yet to hear of any order where he didn't come through. That doesn't justify his business practices, but its something that needs to be said. That includes many of my own orders. But yes unfortunately that's the way it is, and everybody is patient with him.

 

[tylr]

Gonna take a liberty and chime in as a consumer. Hopefully alleviate some anxious folks nerves down the road.

At this point I've ordered stuff from most of the respected contributors here. I've waited a little bit longer than anticipated a couple times and I didn't always get a status updates when I nagged. In the end, I've received everything I've ever ordered, well packaged, and in the timeline that other members reported.

More importantly, I've also always had support when there was an issue. Like a few posts earlier in this thread when matador answered a question I'd sunk a day or two into trying to figure out myself.

I got several PSU PCBs in about 6 weeks. Several others have had about the same timeline. I think a lot of orders are nervous new builders expecting an amazon experience and it's hard to address all of those.

 

[Roman Beilharz]

Thank you mrgrooves6666 and tylr for chiming in. Well, it's not about my nerves. I am not worried to get my products or my money back or something like that. I trust into this community and so I trust in the trustworthiness of Chunger et al, fully.

But as many others here, I am not a spare time electronics dabbler. I am recording music for a living, I am composing and producing plus I teach at Uni plus I have a family to take care of and organize. So I am working 2,5 jobs and I need to schedule my time, because it is the most valuable resource I have.

I simply can't plan ahead with this kind of business procedure and so I will not recommend it to likeminded people around. Regardless of the fact that everything else about this seems awesome. I would gladly pay more to have a more professional customer experience.

@chunger/ @Matador, in case you read this: What about integrating the sale of your products into the new webshop that Arienneaudio seems to be building?

 

[ElSmurf]

What about integrating the sale of your products into the new webshop that Arienneaudio seems to be building?

That's actually a great idea!

 

[Roman Beilharz]

In the meantime it's almost November, about 10 weeks after I had ordered and paid my parts. Still: no status info, no excuses, no shipment... this is really starting to bug me :-/

 

[kinglok]

I have placed an orders recently. They did deliver finally.

Here's the details for your reference.
Order date: 2 Aug 2023
Shipping date: 18 Sep 2023