audio-talk

Oh yes, I should include that stopper resistor as that'll have a big influence on the grid current - at the moment the voltage sources have an output impedance of zero. Will do that and rerun the comparison later on.

The normal reason to use separate cathode parts is to handle the stage going into class B, not sure just how well the shared cap would deal with that. Good point, I wasn't sure either so I thought I'd have a quick play with that this morning. Firstly I redrew the circuit as the way I'd elevated eve...

I've been doing some research on biasing methods for push pull driver and output stages. The cathode bias methods seem to be divided into two main camps - camp 1 has a single shared cathode resistor, camp 2 has a resistor for each cathode with a corresponding cathode bypass capacitor to ground (the ...

Thanks for the help everyone, appreciated. I think I understand now.

A question to the floor if I may... I was reading a transcript of a talk that Lynn Olson gave to the ETF in 2004 - here: http://www.nutshellhifi.com/library/ETF.html I found it very helpful in terms of understanding signal paths as current loops, and how best to optimise them. However, there is one ...

Here's the video on Youtube.

"We've got three melodies - first gear, second gear and third gear".

Hi Andrew,

Can you tell me if these boards are still available? I'm back to pondering circuits with push-pull 2A3 driving 300B, a requirement of which is decent DC heating on the 2A3 to prevent unacceptable hum levels. So this application would need 4 of them at 2.5V each.

Cheers!

So, where is the dividing line (age wise) between the youngsters who wanted to stay in, and the elders who wanted to exit ? https://pbs.twimg.com/media/ClsFTYkUgAERBxJ.jpg How interesting. So the age group who's pensions are already well sorted thankyouverymuch have just wiped billions off the stoc...

In the kitchen we have a Hacker Hunter RP38A which I think was manufactured before we joined the EEC in 1975. It was on that, that I was listening to the Today programme this morning whilst making my sandwiches and heard Cameron's resignation speech live. Within five seconds of him starting his spee...

Hmm - I don't think the Futterman-based designs can be made balanced in an elegant way - because quite a lot of the circuit is effectively single-ended. You've got that totem-pole output stage that needs the asymmetrical drive to ensure the gains balance properly, and how do you apply global feedbac...

Started drawing this out last night and realised I still haven't got this right - bear with me...

Many thanks to Steve S et al for organising this and making Meredith and I feel so welcome. And thanks to everyone who made the effort to bring stuff along to treat our collective ears. A very enjoyable, and educational, experience.

That's got me thinking too.. I brought my 6AS7 Otl to Owsters when it was a little village pub up the A1. Phase splitting was an ECC81 as was the input valve. I can't 'member what feedback. The amp still works fabby well. It is a Rosenblit/bolt design I just can't remember much but I still have the...

Ok so having done a bit more reading and thinking, realised I don't need the op amp! Just apply the feedback to the cathode of the in-phase input valve. And in fact the phase splitter valve can be kept as is, just turn it into a differential stage by applying the reverse and in phase signals to the ...

When I get a chance I'll try and draw out what I mean in Spice, but I'll obviously need to be careful not to infringe any patents.