Tube Amp Archive

This is so helpful, thank you. It's a great learning curve and I'm glad you pointed out the error in my thinking about the second stage of V1 switching. good idea about adding gain with the cathode cap and again I love how you use a resistor instead of simply switching the cathode cap in and out. Th...

One more question if you don't mind.

For the next build if I want loose the cascade option and just have a switch to use V1 as parallel or just a single stage. In other words what would you do to simply remove the second stage from the circuit? Would it be enough to shunt the cathode to ground?

Hi B - I can't thank you enough for your help with this problem and for taking the time out of your day to help me. Really really appreciate that and I have learnt a bunch here! The amp switches silently and as smooth as butter from parallel mode to cascade. The NFB advice is good too. For now I jus...

Thanks for explaining that about the bigger vs. smaller cap, really appreciate that! In the NFB circuit that switch also has an OFF position in the centre so it is ON-OFF-ON. I really like the option to have an open amp with no NFB and that was why I wired the cap to ground on its own switch so when...

You are a genius B! Thank you so much for your help. This has almost completely dialed out the loud pop. It's much quieter now. I had a .22uf on hand. Out of interest, to make it even quieter, where would I adjust things further on the bottom of the switch that connects stage 2 grid to stage 1 grid ...

That makes total sense! Shame on me for not seeing that myself, of course the B+ is being fed into the voltage divider and right into the grid of stage 2. Well spotted. So does it matter if the bigger coupling cap is before or after the switch, I would imagine it doesn't matter? I could attach it di...

So when I loose that "Upper side of the switch" thats joining the plates of Stage 1 & 2 the pop is a lot better. It is hard to hear the difference but am I correct in thinking I am not hearing both stages in Parallel now and that is is in fact only the second stage when the switch is in 'parallel mo...

Hi - After making those changes there is no difference in the pop when switching, it's still there loud as ever. I was surprised because on paper it all makes sense. The common terminal at the bottom section of the switch now has a cap to grid of second stage and a 1m resistor to ground. 100K plate ...

Thank you B! That's a great response and I appreciate you taking the time to do this. I was thinking the huge voltage/current changes wouldn't be making it easy. So I'm gonna grab an iron and make the changes. Just to be certain: The plate resistor on V2 will be moved to the actual plate side of the...

Thank you Steve! I did try that but let me go back and look again and report back.

Hi guys, I have been designing a circuit and am really happy with the end result and its getting positive responses locally. My final hurdle is a pop when switching. It's a clunky kind of DPDT switch which switches the first 2 stages to parallel or series mode. Before pulling it a part and redesigni...