vigilante398
Authorized Vendor
Nope, the value isn't really critical. Those resistors are just to lessen the risk of popping when switching the tone selector.
Diplomat - Matchless DC30's EF86 Channel
- Thread starter vigilante398
- Start date
Betty Wont
Well-known member
I’m REALLY enjoying using this thing to goose the Black Eye into metal gain territory. My amp is dark (orange tiny terror), and the Black Eye is bright. The Diplomat really wakes up the cancelled frequencies of that struggle. I think I smell a 2-in-1 build coming up!
vigilante398
Authorized Vendor
Bumping the thread to let everyone know that Ambassador PCBs are no longer be available from Sushi Box, from now on they will be sold by Conspiracy to Commit Electronics (@C2C Electronics). I'm still involved, but trying to be less in charge.
c2celectronics.com
Enclosures are still available, but listed separately.
c2celectronics.com
Diplomat PCB Set
This is a PCB set for building your own Diplomat preamp. This is not a beginner project, so if you’ve never built a pedal before, then this isn’t for you. I’ve tried to make this as affordable and …
c2celectronics.com
Enclosures are still available, but listed separately.
Pre-Drilled Enclosure
JULY 30 2024 UPDATE I will be discontinuing the pre-drilled enclosure option for these projects as I have been having trouble keeping up with demand for these enclosures. I have released drill temp…
c2celectronics.com
benny_profane
Well-known member
@vigilante398 there are discrepancies between the BOM and the silkscreen (e.g., two 1k5 resistors spec’d in the BOM, but nothing on the board). Should it be built to the values indicated on the board?
vigilante398
Authorized Vendor
It should be the values indicated on the board, there may be some things in the BOM that got carried over when I reused the template from Particle Accelerator. I thought I had fixed them, but apparently not. I'll get that taken care of, sorry about that.
vigilante398
Authorized Vendor
EF86 is a single pentode, there is only one stage in the tube.
I almost finished my Diplomat (kit from Das Musikding) i just need to add the font.
For now i just bench test it to make sure it is working good, B+ is 257V, plate voltage is 71V and cathode 1,4V.
If i understand correctly it is possible to increase the B+, i can see the HV board (sold separately) have a trimmer to set the voltage.
Is change the resistor 5 and 6 the correct way to increase B+? If yes any tips to go from 257V to 320V?
For now i just bench test it to make sure it is working good, B+ is 257V, plate voltage is 71V and cathode 1,4V.
If i understand correctly it is possible to increase the B+, i can see the HV board (sold separately) have a trimmer to set the voltage.
Is change the resistor 5 and 6 the correct way to increase B+? If yes any tips to go from 257V to 320V?
vigilante398
Authorized Vendor
That is correct, adjusting the ratio between R5 and R6 sets the high voltage from the SMPS. I don't know offhand what will give you 320V, but I typically leave R5 at 4k7 and drop the value of R6. You could try dropping it from 560R to 390R or so, that will likely get you around the ballpark.
Keep in mind that you will want to make sure you are using a 400V filter cap (C1) if you increase the voltage. The 257V on a 250V starts to make me nervous; you can get away with slipping above the rating for a little bit, but if your steady-state voltage is 257V consistently (which is weird, I expect 235-240V with the 4k7/560R setup), it could contribute to an early failure of the capacitor.
OK thanks for your reply, if needed I will adjust R6. And change C1.
... Is increasing the input voltage (the 9V) also increase the output voltage of the SMPS ? I was thinking that 257V was good because it is mentioned 250V on the schematic.
My power supply is the Palmer PWT12 https://www.palmer-germany.com/en/products/power-supplies-chargers/18553/pwt-12-mk-2
It has 4 adjustable outlets 500mA (until 18V), I did set the trimmer to 9V but didn't check the accuracy, it could be a pinch higher.
... Is increasing the input voltage (the 9V) also increase the output voltage of the SMPS ? I was thinking that 257V was good because it is mentioned 250V on the schematic.
My power supply is the Palmer PWT12 https://www.palmer-germany.com/en/products/power-supplies-chargers/18553/pwt-12-mk-2
It has 4 adjustable outlets 500mA (until 18V), I did set the trimmer to 9V but didn't check the accuracy, it could be a pinch higher.
vigilante398
Authorized Vendor
The SMPS is regulated, so the value of the input voltage does not affect the output voltage of the SMPS.
joelorigo
Well-known member
Curious form someone who knows nothing about what you guys are talking about above, why would one want to increase the voltage?
@vigilante398 @Creach
@vigilante398 @Creach
Rpschultz13
Active member
vigilante398
Authorized Vendor
It gives a different character to the sound. It's hard to put exact words on it, but the most common ones I hear from customers are "full", "rich", and "thick". My understanding is that it's similar to solid-state devices in that it increases the clean headroom, but it also changes the way the tube is biased, so it affects the tone and feel a bit as well.
I should note I don't have any specific scholarly articles to reference on this, just my experience with stuff. When I first started doing tube preamps I ran them all at 235-240V (which is where the DIY projects are set), then eventually stepped them up to 350V.
Rpschultz13
Active member
350V, is that a typo???
vigilante398
Authorized Vendor
Nope, my current commercial builds (not DIY projects) use a B+ of 350V.
Rpschultz13
Active member
I'm confused. I'm building the Diplomat and KingNothing. The schematics both say 250V. What am I missing?
vigilante398
Authorized Vendor
The number written on the schematic is arbitrary and is not reflective of the actual voltage of the SMPS. But all C2C projects should be right around 240V.
Rpschultz13
Active member
What are your "commercial" builds?
