Gus

47 preamp related link
« on: June 22, 2020, 08:18:03 AM »
Found this looking for something else. Starts at about the middle of the page.

https://www.tubecad.com/2020/06/blog0506.htm


fazer

Re: 47 preamp related link
« Reply #1 on: June 22, 2020, 09:37:16 AM »
Quote
Think harmonic restoration

I like this description.  Thanks for posting.   

Re: 47 preamp related link
« Reply #2 on: June 22, 2020, 10:08:56 AM »
I like this description.  Thanks for posting.

Yeah me too.  "Harmonic Restoration" should be a feature button on all tube pres. 
Note to self:  Don't let c**ts wind you up

ruffrecords

Re: 47 preamp related link
« Reply #3 on: June 22, 2020, 10:36:28 AM »
It is unfortunate that as well as never having heard of the 47 he did not appreciate the subtleties of its design. For instance the gain of the anode follower is very deliberately chosen so as to largely cancel the second harmonic distortion produced by the EF86. There is a description somewhere of the design - I will see if I can find it.

Cheers

ian
www.customtubeconsoles.com
https://mark3vtm.blogspot.co.uk/
www.eztubemixer.blogspot.co.uk


'The only people not making mistakes are the people doing nothing'

Re: 47 preamp related link
« Reply #4 on: June 22, 2020, 10:54:20 AM »
the gain of the anode follower is very deliberately chosen so as to largely cancel the second harmonic distortion produced by the EF86. There is a description somewhere of the design - I will see if I can find it.
 

Yep, indeed.  I don't have it at hand but it's in the original manual for the REDD.47
Note to self:  Don't let c**ts wind you up

ruffrecords

Re: 47 preamp related link
« Reply #5 on: June 22, 2020, 03:58:10 PM »
Yep, indeed.  I don't have it at hand but it's in the original manual for the REDD.47

https://www.dropbox.com/s/xk4d7dw91uq9pyf/EMI_REDD.47_docs.pdf?dl=0

Cheers

Ian
www.customtubeconsoles.com
https://mark3vtm.blogspot.co.uk/
www.eztubemixer.blogspot.co.uk


'The only people not making mistakes are the people doing nothing'

Re: 47 preamp related link
« Reply #6 on: June 22, 2020, 04:16:01 PM »
Thanks Ian.   
Sure, the amp is of its time and there are things we have access to now that could improve on it. 
But in talking with Ken Townsend (engineer at AR in the '60's, later managing director of A.R. Studios) about the only things that had been overlooked  and were considered negatives back then in regard to that amp were the heat dissipation of 30+ amps in a desk, and the fact that the desk had to be powered down to remove a module due to sharing of power supplies.




 
Note to self:  Don't let c**ts wind you up


 

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