Barry Porter "Net EQ"

[Cardinen]

I can verify the circuit is working.

Gustav

Hi Gustav !

I'll like to try your design of this eq in the next months, i have a few questions:

- I'll split the channel bypass in L and R instead of stereo ( just using 2 relays) what will the MS do ? (single M-S bypass is possible?)
- Did you used 100uF bipolar caps like the original in the audio path or just standard audio electrolytic ?
- Have you encountered any problems in the project?

thanks 

 

[Gustav]

Hi Gustav !

I'll like to try your design of this eq in the next months, i have a few questions:

- I'll split the channel bypass in L and R instead of stereo ( just using 2 relays) what will the MS do ? (single M-S bypass is possible?)
- Did you used 100uF bipolar caps like the original in the audio path or just standard audio electrolytic ?
- Have you encountered any problems in the project?

thanks 

If you think about how M/S works, you will realise what will happen if you mute one channel.
Think of it in terms of soloing M and S as solo functions if you want to implement that.

I attached an example from a different project showing how I did it around the decoder section. There may be easier ways, but this works..

Bipolars used where called for.

Gustav

 

[Cardinen]

Ok i got it now.

thank you, M/S solo will be a great function! 

 

[bruno2000]

I have built some Net EQ modules and have found that the "linear" implementation of the boost cut ladder (using a switch) does not exactly correspond to the desired boost/cut figures.  I have worked out values for the resistors that come really close (+/- 0.1 dB) for what I wanted.  I'll publish my values if anyone is interested.
Best,
Bruno2000

 

[Cardinen]

I have built some Net EQ modules and have found that the "linear" implementation of the boost cut ladder (using a switch) does not exactly correspond to the desired boost/cut figures.  I have worked out values for the resistors that come really close (+/- 0.1 dB) for what I wanted.  I'll publish my values if anyone is interested.
Best,
Bruno2000

Yes i could be interested if you can post it;

 

[bruno2000]

Here you go.
Best,
Bruno2000

 

[bruno2000]

My version.
Best,
Bruno2000

 

[5v333]

bruno thats sick tight!


i have been planning for a while on my own version of the bpnet eq. i have downloaded this schematic
http://www.collinsaudio.com/NetEQ.pdf
and i see that it differs some from harpos schematic.
http://www.hausverwaltung-heger.de/al_leck_trick/Porter_NetEQ_H.pdf

the pots around q, freq, and gain are wired differently and some resistors are different around thoose pots.

is there a right version here?

the gain setting in harpos version seem to disconnect the juction to one of the two summing amps depending on cut or boost operation. seems like a cool idea but shouldnt the disconected end be terminated to ground atleast..?

 

[bruno2000]

bruno thats sick tight!


i have been planning for a while on my own version of the bpnet eq. i have downloaded this schematic
http://www.collinsaudio.com/NetEQ.pdf
and i see that it differs some from harpos schematic.
http://www.hausverwaltung-heger.de/al_leck_trick/Porter_NetEQ_H.pdf

the pots around q, freq, and gain are wired differently and some resistors are different around thoose pots.

is there a right version here?

the gain setting in harpos version seem to disconnect the juction to one of the two summing amps depending on cut or boost operation. seems like a cool idea but shouldnt the disconected end be terminated to ground atleast..?

I used Harpo's circuit, (x5) with a 5k equivalent boost / cut pot with a switch, and did use a 5k resistor from the unused summing amp input to gnd.  Harpo was amazingly helpful with his explanations and spread sheets.  I should have put his name on the front panel as well.........
I also added the M/S encode/decode circuit from Wayne Kirkwood, and the SSL 18 dB/oct HPF.
Best,
Bruno2000

 

[5v333]

http://www.americanradiohistory.com/Archive-Wireless-World/80s/Wireless-World-1984-01.pdf

page 73

 

[Bonsaimaster]

Can someone help me figure out how to make the HF shelf switch allow for selectable freq? Also what is the HF shelf set?

 

[5v333]

hi!

the hi shelf freq is set by (1/2πRC) C77+C81 (1nf+6.8nF) and R91+P15 (1K+Pot). when the P15 is turned to minimum resistance, only R91 is part of the formula and sets the freq to about 20Khz.
when P15 is turned for maximum resistance, the total resistance should be about 11K for 2Khz.

the HI shelf and HI bell are separate filter circuits. with the switch, one of them is disconected from the gain pot of that band, while the other is in effect.

 

[Bonsaimaster]

Thanks that was a great explaination. So my question is that is there a way to put another gain pot in play when the HF switch is engaged to change the freq of the shelf? Also if the HF self is engaged what freq is it set?

 

[5v333]

the HF freq is variable - both in the bell circuit and in the shelf circuit - with the same pot. the LF and HF freq pots  are triple ganged.

each band has its own gain pot.
LF bell and shelf shares a common gain pot.
HF bell and shelf shares a common gain pot.

if you want  to separate bell and shelf in any band you need to split the tripleganged freq pot in to one dual pot and one single pot.
if you want to have separate gain for shelf and bell you have to insert an additional gain pot and wire it similar to P14 P11 P8 P5.

 

[Bonsaimaster]

Ok that is what i needed! thx Can i ask which set of three connections would effect the shelf?

Ones
toward the outside of board
middle or
inside board?

 

[5v333]

i am only refering to the schematic. i have never seen a pcb...

if you tell us which pcb you have, maybe some one can help you with that.

 

[Bonsaimaster]

looks like the pot connections that go to R91.

 

[hazel]

I finally got a couple of boards to build my own Net EQ

It's intended for mastering at studio and mix duties. I need transparent parametric EQ with stereo ganged controls. Surgical EQ is done ITB so I tend to use hardware for broad strokes, sometimes with evident sonic imprint and sometimes invisible. No need dual mono controls as it kills my workflow. Want to keep EQing eyes closed.

Features:

- HPF stereo ganged (4 decks 24 pos or a simple 4 decks x 3 pos). Frequencies not decided.

- OUTPUT GAIN dual mono (1 deck 24 pos). +/- 5'5dB

- Q stereo ganged (2 decks 6 pos). Standard values

- GAIN stereo ganged (2 decks 24 pos). +/- 6dB

Due to expensive 6 decks rotary switches i decided to split HF selectors

- HF BELL FREQUENCY stereo ganged  (4 decks 24 pos). Standard values

- HF SHELF FREQUENCY stereo ganged (2 decks 24 pos). Standard values

So this way I can A/B between different frequencies and shape by pressing a button


I will source switches from Uraltone (4 decks 24 pos):

http://en.uraltone.com/electronic-components/switches/rotary-switches/rotary-switch-4x24.html

Don Audio:

https://www.don-audio.com/Rotary-Switch-2024-2-Pole-24-Position

and  Banzai:

https://www.banzaimusic.com/Rotary-Switch-BR-2x6-Pins.html

https://www.banzaimusic.com/Rotary-Switch-BR-4x3-Pins.html

I'll post progress as soon as I order parts.

Attached a very preliminar front panel design. I'm open to suggestions on ergonomy and workflow

 

[5v333]

Hi!

Hope youll have a great build with good results!!

Looking at your panel.. are thoose holes for switches or do they represent the knobs on the switches?

The far left and far right switches seem like they might be too far out to the sides..?

 

[hazel]

Looking at your panel.. are thoose holes for switches or do they represent the knobs on the switches?

The far left and far right switches seem like they might be too far out to the sides..?

Thanks for your kind words

Holes represent switches. They are 40mm diameter.

Had some "ouch" moments in the past designing a nice panel forgetting switches and pots attached to haha

Still not decided between Manley or Sontec style Knobs. I'll operate this eq without looking at it so it must have recognizable shape at touch.

I'll post updated pics and sketches when sourcing parts.

Yes you're right on gain  switches at far left. I should place them better. I was just trying to figure out global layout.

I'm still not sure about F, G and Q placement. It seems like there are two ways:

- controls placed top to bottom F, Q, G or Q, F, G. Most Net EQ builds, Prism, Sontec...

-controls placed top to bottom G, Q, F so workflow leads from bottom to top like Manley Massive Passive

Both have pros and cons. I like traditional way top to bottom but I also love to have Manley having Gain at top so can put my hands on it with out accidentally touching Q and F