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I'll try that. It's a brand new Alpha pot, DPDT push-pull.

It's amazing how much a tiny 220-ohm resistor can change everything..... :LOL: Now this thing is loud. Much louder than I could have imagined for an 18W amp. However, some unwanted noise has started to appear, but strangely enough, only when the master volume is between 75% and 95%. When I set...

And It shows exactly my 300V and 200V. Your tool is excellent and confirm exactly my mistake. 👍 And the 0V at grid of V2b is probably why my amp is so low volume.

I've find this afternoon I forgot the 220R resistor (R18), hidden in the centre of the V2 socket. Can you try without 220R (cathode resistor) in your modelling app ? As soon as I'm back home tomorrow morning, I'll solder R18. Maybe that's also why the amp is low volume.

Hello, everyone! I received the kit from Tube Town, Germany, along with the various parts I needed to make the modifications I wanted. As is often the case with purchases from Germany, everything arrived, no mistake, well-packaged, clearly labeled, and well-documented. I started the build with...

Sure ! That's why I said "as long as the transformers can handle it" which means I will check if they can if/when I decide to boost this little amp.

I'm actually going to order a set of ceramic capacitors from Amazon. I'll run some tests. I couldn't help but look into how to add a pair of 6V6GT in addition to the one already there. It doesn't seem that complicated (as long as the transformers can handle it); it's almost a copy-and-paste of...

Ok, no lights when I'll start the damn thing. I got it. :LOL: I think now I have all my answers. Time has come to order.. One last thing : I will opt for a switchable 1Mohm log MV pot to include a bright cap. 100pF seems a good value to start (good effectiveness for bass frequencies ? ceramic...

It may be a paraphrase inverter as I found someone who made some modifications in a that amp years ago mentioning it : Quote : "Hi, I made a bflex for my bass player a few months ago. It was working fine but, even if I added a line out, it was good for practice, but too weak for the rehearsals...

Ok, let's try Option 1 and see if the overdriven V2a+b sound musicals. If not I'll go for option 2. Ok for the grid stopper on V2a, but why not on V2b also ? I also notice there are no grid stopper on V1a and V1b. Could this be an good enhancement to add grid stopper here too ? My room is...

Thank you @JohnnyCreepy , that makes sense. As for the pre-PIMV, I found two solutions and I can't figure out which one to choose : - Here's the Volume pot from an amp kit similar to the TT B-Flex. It features two resistors (voltage divider shape, 470k and 1Mohm) + a 1Mohm pot : Larger...

Thank you, everyone!! You’ve given me plenty to learn and a few problems to solve. Now I have some decisions to make: - Which solutions to use for the Master Volume, keeping in mind that there aren’t really any right or wrong methods. I just need to choose the one that works best for me based on...

As a chief engineer in the merchant marine, I hope being able to stay vigilant, although I also know one should never be too confident in this kind of situation. Thank you for reminding us of this basic principle: high voltage can indeed cause serious harm. That's a great idea; I'll look into...

I plan to use it in my home studio or for small blues jam sessions with my guitarist friend. I have an Ampeg Micro VR, a 160W solid-state amp, for when I need more volume. The goal of this DIY project is to have a small tube amp at home, but above all to learn and expand my knowledge. This is...

Thanks for these advices. I need to think about that—it might be interesting to have a mid-range control. But I'm afraid that if I give up the Baxandall tone stack, I'll lose the “Ampeg Portaflex sound" (even if SVTs are famous for their midrange control...).

Thank you both. These are some things to think about before I place my order. I've found this schematic. If I understand correctly, I'll need to replace R24 and R25 with a two-stage 250kohm log potentiometer. And add 2x1.8Mohm safety resistors to maintain the initial values of approx 270k...

Do you think I should put the MV before the tonestack ? Is that what you mean by "changing the tonestack structure" ?

Hello, everyone! I’m planning to build a tube bass amp using this kit from Tube Town in Germany. It’s a kit inspired by Ampeg’s Portaflex series. I’m thinking of making a few modifications: - Add a volume potentiometer (1 Mohm log) in place of resistors R14 and R15. Passinwind recommended...

From what I can gather from this document, there is a 10% tolerance on the filament voltage to compensate for variations in the supply voltage. For a filament that is supposed to be powered at 12.6V, the tolerance allows for approximately 11V. That is 2V more than 9VDC. But since the filament...

I confirm 180V for JJ and 150V for TAD. Far more than needed in our case.