audio-talk

Hi Chris some web reports say the driver software is in the touch, is this true??(seems unlikely) I ask because I run a hacked buffalo linkstation as a server and it cant go beyond slimserver 6.2.2 if the server s/w is inside the touch presumably it doesn't need an external server, it just needs a ...

What!

They all play croquet and table skittles in Skellow Grange Club.They hit each other with hammers and knock one another over tables

Steve

Yeah but no but, that's how it always is ~ i/p cathode has to be unbypassed somewhere else can't use it as an "input" for NFB, so precludes that the stage starts off with current (cathode) feedback anyway. Aha the penny drops! That's why leaving the cathode unbypassed raises the ra of the...

What's interesting about that is it is a very similar idea to that in the RCA book where the feedback resistor is taken from the o/p anode, i.e. OPT primary. The difference here is it's off the secondary instead. Yes Scroggie also describes that method whereby a potential divider from the anode of ...

Hmmm... Tried the global feedback; not bad, but the bass, though tight, seemed to have somehow been for want of a better description, "thickened". The depth and extension were all there but differences between bass instruments got a bit smoothed over and homogenised. Trying the feedback to...

Nick wrote:Well, the unbipassed cahode will be adding negative feedback, so it will be adding to the feedback from the output transformer, further reducing the gain.

Hmm a nested local feedback loop enclosed by a global one then. Yuk!

Cheers Nick, Just one thing about the global feedback option. As the cathode of the C3g is unbypassed, is the feedback introduced through this path going to oppose or add to the negative feedback from the OPTX? I reckon it would oppose the main feedback loop, and render it less effective unless the ...

Why not take the feedback to the c3g stage? That way its not asking the driver to drive the summed error signal. I see, yes It's perfectly feasible to go to the grid of the C3g rather than the 13E1. I know Scroggie/Jones and everyone else mentions this but then warn about introducing possible insta...

Been doing some further reading of taking feedback to grids rather than cathodes. Re the driver stage - instead of merely seeing the high impedance grid of the power stage, the driver stage also sees the feedback signal. You have to be careful of this or your input resistance will be too low. It usu...

Anyway here is the current schematic with the feedback setup highlighted in red. http://web.me.com/scress1958/Pictures/13e1tetmode.gif A good way to experiment might be a 250K mono pot, wired as a rheostat to replace the 100K feedback resistor, tried as the first one that came to hand. With a pot, d...

he makes some interesting observations on that page Steve. Can you remember back far enough to guess how it compares to rocky? I'm guessing its a refined rocky kind of sound....I'm not sure about the differences between ecc81 and 6sn7(the one I used)....but.... I ran my original(grounded g3) with S...

OK... Changing the feedback scheme has removed the stridency, so we now have three SEPs, two anode followers and one with transformer secondary to power valve grid feedback. Both schemes work very nicely. Incidentally, I found the power stage transformer to grid feedback scheme in Scroggie Foundatio...

OK Back to the 13E1 for a little while. I have an EL84 working beautifully, but listening to the 13E1 again, it does seem a little loud and strident by comparison. There's oodles of power there but finesse is a lacking. Phil's "subtlety and sweetness" is a bit down on the amp's list of pri...

I'm fresh out of output transformers, so has anyone got a pair of 5K single ended output transformers they might loan out for a short period? I'd like to try a few more single ended pentode amps KT66, KT88 etc. A loan of a pair of these TXs would be much appreciated. Can collect in Yorks of course. ...

It's starting to look like the later date.
That's fine for me too

Steve