vigilante398
Authorized Vendor
The jury is out on that one. Some people swear they hear a difference, others swear they don't.
Tungsten Preamp - another weird D.I. thing
- Thread starter vigilante398
- Start date
Winterbloom
New member
I understand. Question is if there is more headroom with 12V, or in other words, if you got more distortion with 9V?
vigilante398
Authorized Vendor
That's what I assumed you meant, and my answer still stands. The input voltage is fed directly to the tube heater only, the plate voltage generated by the SMPS doesn't change, and that has much more impact on the tone than the heater voltage does.
Winterbloom
New member
Thanks again! My knowledge about tube circuits is very little, so that is interesting to know.
Tassieviking
Active member
There are some great calculators for tube circuits if you want to learn some more, https://www.ampbooks.com/mobile/amplifier-calculators/
I use them a lot because I like to understand what is happening on any pedal circuit that I build
Cheers
Mick
Winterbloom
New member
@vigilante398 I have the Particle Accelerator as a kit from Musikding.de (very convenient), but have not built it yet. Yesterday I ordered three more PCBs directly at your website (Bathtub, Tungsten and Vampire Slayer). I am going through the build guides and I have two questions:
- Tungsten Preamp: What is this RADJ for, and why is it optional? It seems it is important for the voltage rating of C1, but what means this exactly?
- As far as I could see in the other build guides, there is always this 10uF elko at the end of the power supply. In the Tungsten it is named C9, in other builds it has other names (C6 e.g.). It is rated 250V in the BOMs. But: is this not to little rated? I thought, it should be at least 400V, since the overall voltage is 250V?
Thank you as always for your knowledge and help! I am happy to build these nice tube treasures!
- Tungsten Preamp: What is this RADJ for, and why is it optional? It seems it is important for the voltage rating of C1, but what means this exactly?
- As far as I could see in the other build guides, there is always this 10uF elko at the end of the power supply. In the Tungsten it is named C9, in other builds it has other names (C6 e.g.). It is rated 250V in the BOMs. But: is this not to little rated? I thought, it should be at least 400V, since the overall voltage is 250V?
Thank you as always for your knowledge and help! I am happy to build these nice tube treasures!
vigilante398
Authorized Vendor
RADJ goes in parallel with the other resistor to set the high voltage of the circuit. This is optional because the original preamp that Tungsten is based on runs with a voltage rail of about 240V, and if you leave off RADJ then your high voltage will be somewhere around 235V. If you put a 1kΩ resistor in for RADJ then you will get something around 340V, which is higher than the original but which I personally liked for this circuit.
A 250V rated filter cap for the high voltage is the minimum that I would use on a 235V rail, and it is not unreasonable as there should not be variance in the SMPS output like there would be in a transformer-based supply, but it would of course be a good idea to go higher if you have access to higher-rated parts as it is always good practice to over-spec filter capacitor voltage ratings. Obviously if you install RADJ for a higher voltage rail then you will need a higher rated capacitor here.
Winterbloom
New member
Thanks!
I think there is also a mistake in the BOM of the Tungsten: C1 is there two times. I guess the "second" C1 with the little stars should be this C9 in the schematic, which I meant before (10uF electrolytic).
I think there is also a mistake in the BOM of the Tungsten: C1 is there two times. I guess the "second" C1 with the little stars should be this C9 in the schematic, which I meant before (10uF electrolytic).
