45 Amp Circuit

[pre65]

Hi-i recently bid on e-bay for a 45 amp with bits missing,but lost out.

I am trying to trace the circuit but google has let me down!

It is by Gordon Rankin of Wavelength Audio (not the Bugle !) and is called a "constant current output stage direct coupled 45 amp" using the ECL82 as driver/current source and 5U4G rectifier.

any information,or link would be appreciated.


Philip

[andrew ivimey]

Hi Philip, what's wrong with the Bugle?! It is so sweet (and the right chokes etc for the PSU are arriving later).

Here's a thing though -

Ques.) why is the 45 such a revered valve?

Ans.) because it is so linear.

Why is 'linear' so good for audio???

I don't mean to, but don't mind too much, sounding so ignorant, but why is linear so good for audio? Why couldn't they then get 2A3 or 300b right, or did they and it is just a matter of being different?

What little experience I have of 45 is that it has a remarkably fine sound

I found the Bugle from the Bottlehead magazine 'VALVE'. I guess you are looking for 'Sound Practices'; a near legend, long out of print and if you do find them, I'd love to read over your shoulder!

[James D]

Saying a valve is 'so linear' is just another way of saying it sounds very good .

Linear is good but without context and measurments its not got a lot of meaning beyond 'low audiable distortions', 'faithful micro and macro dynamics', 'preserves tonal colour and discriminations', 'has that certain magic that makes me listen more'. Take your pick!

James

[andrew ivimey]

A 45 is soooooooooo linear ha ha!

[Ianm2]

its the balance between even and odd order harmonic distortions that makes valves musical.

linear is good because you don't need feedback.

feedback is good as it gets rid of distortion. but not in single ended amps.

[James D]

God I wish the world was a simple as Ian states

It would have saved an awful lot of time and money...

...and why doesn't feedback get rid of distortion in SE amps if it does in others?

James

[IslandPink]

...and why is a 300B so much harder to drive than a 2A3 , given the miller capacitance is about the same ...?

MJ

[James D]

'cos the signal is twice as big? i.e. 100V p to p rather than 50V...

[Ianm2]

I didn't mean feedback gets rid of distortion, just its not really much good for the sound in sets

[James D]

Ahh, sorry Ian, misunderstood you there. I would say global feedback isn't much good in any amplifer regardless of type or topology. Before I came back to valves I had removed global feedback loops from my ss designs to good sonic effect. Lots of local loops but no globalones or even two stage ones...

James