Audio Note vs. Aries Cerat vs. darTZeel

[DasguteOhr]

I am using an Incito preamp with my Protos and fixed Protos as a power amp…find that works better with non-AC sources.

I don't know the shematics is a input transformer inthere?maybe create a filter with caps

 

[Aries Cerat]

I set it to 20 per recommendation from the manual, but I was about to ask about that because it fluctuates quite a lot, and it’s probably not supposed to do that? Maybe I should switch to the “intended” supplied tubes and see if they are more stable?

Hi
The bias will drift for three reasons
While tubes warm up and settle.6j11 change quite a bit while warm up
While they burn in after new install,takes few days to fully settle.
Also bias drifts while following mains voltage variation within the day.
The bias meter being digital and accurate enough has the downside that make user osc about it when it changes a bit .Do not overly think about it ,let it drift while in the day, as it will track the psu change.
Only change tube if you see big changes downwards during the days.

Do experiment with higher and lower values,as long as you are within operating envelope, try and find you like more.

Cheers
S

 

[VoicesInMyHead]

If these are NOS tubes that have still been used, then it can vary. Put the tubes in the oven for 3 hours at 130-150 degrees, then let them cool down before opening the door. Then try again. It's a tried and tested trick. I do it for every 6c33 tube. I think it works for your tubes too. If it doesn't run stable then new tubes will be needed.
you age the tube with the procedure then usually run more stable.

nice! I have never heard of tube baking before, but makes sense!

 

[VoicesInMyHead]

Hi
The bias will drift for three reasons
While tubes warm up and settle.6j11 change quite a bit while warm up
While they burn in after new install,takes few days to fully settle.
Also bias drifts while following mains voltage variation within the day.
The bias meter being digital and accurate enough has the downside that make user osc about it when it changes a bit .Do not overly think about it ,let it drift while in the day, as it will track the psu change.
Only change tube if you see big changes downwards during the days.

Do experiment with higher and lower values,as long as you are within operating envelope, try and find you like more.

Cheers
S

thanks! this all seems very reasonable. with the "spare tubes" I had one tube drifting off from 20 almost down to 15 and the other in opposite direction from 20 to 24 which just seemed a bit much to me, but as you say it can maybe be burn in and other reasons. I popped the other tubes back, not sure it makes any difference, but that's how it goes in my head if something is marked as "spare" or "backup"...

my friend who helped me set it up actually said "this is the reason I can't buy this amp, I would not be able to calm down unless those numbers are in sync!", I think I'm a bit more chill about it though...

is it possible to say what happens or what to expect to sound character going up versus down? or does it depend on tubes?

btw, thank you SO much for the instant support the other day, it made all the difference to me!

 

[DasguteOhr]

nice! I have never heard of tube baking before, but makes sense!

you heat up cathodes without plate current, no stress for tubes. Unfortunately there are some Russian tube types where there is a lot of waste, sometimes it takes 6-7 pieces before you have 2 perfect ones.

 

[Aries Cerat]

thanks! this all seems very reasonable. with the "spare tubes" I had one tube drifting off from 20 almost down to 15 and the other in opposite direction from 20 to 24 which just seemed a bit much to me, but as you say it can maybe be burn in and other reasons. I popped the other tubes back, not sure it makes any difference, but that's how it goes in my head if something is marked as "spare" or "backup"...

my friend who helped me set it up actually said "this is the reason I can't buy this amp, I would not be able to calm down unless those numbers are in sync!", I think I'm a bit more chill about it though...

is it possible to say what happens or what to expect to sound character going up versus down? or does it depend on tubes?

btw, thank you SO much for the instant support the other day, it made all the difference to me!

Hi

Do not overthink about the meters not being in exact on sync. Just for reference, if these were analog meters , you would not even notice movement, but when you have digital meter with 0.X resolution , the accuracy goes against the peace of mind

If you go above sweet spot, the tonality "thickens" a bit and vice versa.
The sweet spot value depends on tube type, tube batch, and system/preferences.
Take your time to learn the amp at ~20 and then try ~16, and then ~30ish values, see what it does to you and your system.
If you get the sonic differences on two bias ends, it gets more intuitive to play around and fine tune.

This type , depending on batch when freshly installed, it will either go significantly down or significantly up.

My pleasure, thank you

 

[morricab]

Hi

Do not overthink about the meters not being in exact on sync. Just for reference, if these were analog meters , you would not even notice movement, but when you have digital meter with 0.X resolution , the accuracy goes against the peace of mind

If you go above sweet spot, the tonality "thickens" a bit and vice versa.
The sweet spot value depends on tube type, tube batch, and system/preferences.
Take your time to learn the amp at ~20 and then try ~16, and then ~30ish values, see what it does to you and your system.
If you get the sonic differences on two bias ends, it gets more intuitive to play around and fine tune.

This type , depending on batch when freshly installed, it will either go significantly down or significantly up.

My pleasure, thank you

With my E280Fs, I have settled on between 20-22. Once fully warmed up they land in this range and fluctuate a bit but not really above or below that range.