XAXAU

Neve Silk
« on: January 23, 2017, 02:10:59 PM »
Hey guys I was wondering how Neve does their red and blue silk thingy which a lot of people seem to be raving about. The only thing I've find out is that they're reducing the negative feedback on the output transformer.

Also I'd like to know if it's doable in a 1290? I'm doing a 1290 dual preamp slash summing mixer and it would be fun to be able to go from smooth on buses to obliterated on preamp duties!

Found some documents:

http://www.lundahl.se/wp-content/uploads/datasheets/feedback.pdf

And

http://www.analog.com/media/en/training-seminars/design-handbooks/Op-Amp-Applications/Section6.pdf

Search the document for "Mixed feedback driver"


It´s all a bit too complex for me to grasp!
« Last Edit: January 23, 2017, 03:07:30 PM by XAXAU »


pucho812

Re: Neve Silk
« Reply #1 on: January 23, 2017, 05:29:00 PM »
Is the silk similar to glow and sheen?  When Neve was doing the channel in a box and 9098 circuits, they had a glow and sheen button which did a very gentle slope on the shelf glow on the low end sheen on the high end doing  a 3dB slope. 
You tell me whar a man gits his corn pone, en I'll tell you what his 'pinions is.

XAXAU

Re: Neve Silk
« Reply #2 on: January 23, 2017, 07:00:32 PM »
Is the silk similar to glow and sheen?  When Neve was doing the channel in a box and 9098 circuits, they had a glow and sheen button which did a very gentle slope on the shelf glow on the low end sheen on the high end doing  a 3dB slope.
The glow and sheen seems to be an eq thing while the silk is about lowering the resistance in the transformer / amp feedback path producing more harmonics / THD and changing the frequency response.

"The Silk / Texture works by reducing negative feedback on the output transformer and adjusting the frequency response to more closely resemble Mr. Rupert Neve’s vintage designs."

I guess they´re lowering the feedback and implementing some sort of equalisation in the path.

https://assets-ponticlaro.netdna-ssl.com/rupert-neve/media/2014/12/portico542manual-rev-A-master.pdf


XAXAU

Re: Neve Silk
« Reply #3 on: February 10, 2019, 11:17:41 AM »
Did anyone find out how this is done and if it could be implemented in say a EZ1290 on the output trafo?

"Silk reduces the negative feedback on the output transformer, adding harmonic content as the texture is increased. Silk Blue mode features more saturation in the lows and low mids, where as Silk Red accentuates the saturation in the high-mids and highs."

My3gger

Re: Neve Silk
« Reply #4 on: February 10, 2019, 12:53:02 PM »
Have you checked if Portico has OT with tertiary tap? If so, approach will be different from more ussual way of taking feedback from OT by means of resistors and capacitors. When worked on EMI BRED806, guys from Cinemag helped by sending app notes for their CM-9600-T with tertiary tap (FB controlled by value of resistor, beside tap's ratio).  CMOQ-1 should be able to work this way too, here are app notes: http://cinemag.biz/application_notes/application_notes.php
I found tertiary FB tap lowers distortion a lot, in case of BRED806 so much i would rather work with solid state if starting once again.
Haven't checked data from Portico enough (THD seems high for NFB from tertiary), it could give some hints about method for lowering THD if you don't have access to one.

boji

Re: Neve Silk
« Reply #5 on: February 10, 2019, 09:01:17 PM »
Is balanced primaries a popular thing?  I wonder what changing the phase response outside of the audio band on one of the primaries would do to the output.

Michael Tibes

Re: Neve Silk
« Reply #6 on: February 11, 2019, 06:15:28 AM »
Did anyone find out how this is done and if it could be implemented in say a EZ1290 on the output trafo?

"Silk reduces the negative feedback on the output transformer, adding harmonic content as the texture is increased. Silk Blue mode features more saturation in the lows and low mids, where as Silk Red accentuates the saturation in the high-mids and highs."

Afaik the 1290 / 1073 etc family  does not include the output transformer in the feedback loop like later designs - if that is what they refer to. Have you heard the effect? It does sound a bit like a gimmick to me, but I've never heard it. Just wonder if you might be chasing ghosts here...

Michael

FunkyB

Re: Neve Silk
« Reply #7 on: February 14, 2019, 04:46:52 PM »
http://koo.corpus.cam.ac.uk/rnd-portico-schematic/

I'm not sure whether posting this is in line with the forum rules or not, since not all component types and values are specified.
Please delete this post if it's against the rules :)

abbey road d enfer

Re: Neve Silk
« Reply #8 on: Today at 08:20:38 AM »
http://koo.corpus.cam.ac.uk/rnd-portico-schematic/

I'm not sure whether posting this is in line with the forum rules or not, since not all component types and values are specified.
Please delete this post if it's against the rules :)
Many thanks for posting this enlightening document.
Who's right or wrong is irrelevant. What matters is what's right or wrong.
Star ground is for electricians.

Re: Neve Silk
« Reply #9 on: Today at 12:29:31 PM »
If i got it right, the silk function is just adding/coupling up to 0,6V of DC voltage to the pre transformer signal ?


Gus

Re: Neve Silk
« Reply #10 on: Today at 12:47:54 PM »
interesting

Something a little off topic

R.G. posted about wha inductors and magnetisation of the core years ago on forum s and geofex.com,look for "the technology of wha pedals" at geofex.com there is a section about this. Look at the top left for the "technology of the" to find it, can't seem to get a direct link to the page

I believe I have read posts were people have tried using small EI transformers as wha inductors and introducing DC in the other side winding. I don't remember anyone posting it helped.


abbey road d enfer

Re: Neve Silk
« Reply #11 on: Today at 01:17:07 PM »
If i got it right, the silk function is just adding/coupling up to 0,6V of DC voltage to the pre transformer signal ?
Apparently RN deems necessary to increase the HF response in conjunction with the amount of DC current.
Who's right or wrong is irrelevant. What matters is what's right or wrong.
Star ground is for electricians.

Re: Neve Silk
« Reply #12 on: Today at 04:07:35 PM »
interesting

Something a little off topic

R.G. posted about wha inductors and magnetisation of the core years ago on forum s and geofex.com,look for "the technology of wha pedals" at geofex.com there is a section about this. Look at the top left for the "technology of the" to find it, can't seem to get a direct link to the page

I believe I have read posts were people have tried using small EI transformers as wha inductors and introducing DC in the other side winding. I don't remember anyone posting it helped.

This one?