Barry Porter "Net EQ"

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Slime_Lord

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Gold said:
All four of the bell sections are the same except for the component values. The low mid sections should behave the same way as the other bands.

I’ve gotten behavior like that when I’ve miswired a switch or two. I’d compare the low mid sections to a working section. Double check component values and connections.

Good point, I’m taking it out of the case tonight and will check my wiring, it’s entirely possible I made the same error twice  ;D

EDIT:  Had a 100K resistor at R100 on both boards, switch it to 10K per the schematic and now everything is working as it should!  What a great EQ!
 

r2d2

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ruairioflaherty said:
Hi All,

I have gerbers for Barry's own PCB design as well as a PDF outlining the circuit.  I don't have the means to host the Gerbers so I put them up on yousendit - perhaps someone can download and host.  I don't know if they are good or not as I have neither the skills nor the Gerber reader to tell.

https://download.yousendit.com/WnBReFlZYXkzMWwzZUE9PQ

Can whoever ends up hosting this let me know and I'll email them the PDF of the circuit description.

Cheers,
Ruairi

edited for many typos - too tired. Will email to the GroupDIY account later

Hi Ruairi
any chance for a file re-up ?
thanks
 

Darioricordi

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Oct 24, 2019
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ruairioflaherty said:
Hi All,

I have gerbers for Barry's own PCB design as well as a PDF outlining the circuit.  I don't have the means to host the Gerbers so I put them up on yousendit - perhaps someone can download and host.  I don't know if they are good or not as I have neither the skills nor the Gerber reader to tell.

https://download.yousendit.com/WnBReFlZYXkzMWwzZUE9PQ

Can whoever ends up hosting this let me know and I'll email them the PDF of the circuit description.

Cheers,
Ruairi

edited for many typos - too tired. Will email to the GroupDIY account later
hi, do you still have those gerber files? Can you share it to me? Thank you
 

MidnightArrakis

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hi, do you still have those gerber files? Can you share it to me? Thank you

Hi Ruairi
any chance for a file re-up ?
thanks
I have placed the "Net EQ" GERBER files onto an online web-storage site that I maintain. Here is the link for anyone who wishes to download these GERBER files for themselves. All of the GERBER files are contained within a single ZIP-file:


Now, can someone send me the "Circuit Description" PDF file? THANKS!!!

Regards,

JBWilliams

/
 

druu

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I have placed the "Net EQ" GERBER files onto an online web-storage site that I maintain. Here is the link for anyone who wishes to download these GERBER files for themselves. All of the GERBER files are contained within a single ZIP-file:


Now, can someone send me the "Circuit Description" PDF file? THANKS!!!

Regards,

JBWilliams

/
The circuit description is in the file I/you uploaded, named "neteq doc.pdf".
 

JMan

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Interestingly, I think you both uploaded the same folder of documents. Thank you for sharing these resources!
 

ruairioflaherty

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Way back when I originally shared the Gerbers with Gustav for the first run of boards there was some issue that needed correcting. I can't remember what it was. I'm not sure I could find them now.
 

druu

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Way back when I originally shared the Gerbers with Gustav for the first run of boards there was some issue that needed correcting. I can't remember what it was. I'm not sure I could find them now.
Pretty sure it was the drill holes. I fixed this manually back then, I’m sure I still have the files here somewhere. I’ll upload them when I get a chance.
 

weiss

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So i found out that center tapped potentiometers not really are needed to make the unit function properly! EDIT: THEY ARE NEEDED

I measured my eq with impulse response (see the attached screenshot): The low band and the high mid band completely works on both channels, left and right. But i still got some problems remaining. Now i was able to visualize it:

It clearly shows, that at a maximum gain setting the low mid band only can reach 2db of gain compared to the 10db gain increase in the other bands.. As this occures on both channels, where would i need to start looking? I already measured the resistors of the low mid band and looked for wrong capacitors.. i am really lost

Also i got these weird moving spikes on the right channel. What could be the reason for that?
Is this just due to the measurement?

EDIT:

Problem solved thanks to Slime_Lord. Just like him i had 100k on R100.



Bildschirmfoto 2021-06-13 um 19.18.16 Kopie.png
 
Last edited:

petermontg

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If anybody has any spare boards going I'll take a pair off you.

If not I'll do a run at the end of the summer. 5 pairs if anybody is interested.

Best
Peter
 

weiss

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This eq is amazing. Already loving it after a few weeks.

I'm planning on including lundahl transformers into the chain.
I got two LL2801 but i'd like to confirm the pin layout:

+ IN 7
- IN 6
+ OUT 9
- OUT 10

is that correct? Before the output would be the best place in the circuit, right?

thanks
 

porkyc

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"So i found out that center tapped potentiometers are not really needed to make the unit function properly!"

When Barry first "published" this "feed forward" architecture in a Wireless World Circuit Ideas, no centre-tapped level control. (There had been some verbal aggro in UK between a couple of circuit designers as to the IP of this).
The MCI JH600 console EQ uses this method, no centre-tap.
There is a discussion that Dolby Labs came up with this architecture first, again no centre-tap level pot.
If I were building one, I would like centre-detented level pots, but the statement that centre-tapped are mandatory, is not the case.
For me, the awkward requirement is the triple-gang frequency pots for the top and bottom shelving, as opposed to unbalancing the 2 integrators of the SVF.
Its beauty, though is its flexibilty; it is eminently hackable.
My 2p's worth.
 

weiss

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"So i found out that center tapped potentiometers are not really needed to make the unit function properly!"

When Barry first "published" this "feed forward" architecture in a Wireless World Circuit Ideas, no centre-tapped level control. (There had been some verbal aggro in UK between a couple of circuit designers as to the IP of this).
The MCI JH600 console EQ uses this method, no centre-tap.
There is a discussion that Dolby Labs came up with this architecture first, again no centre-tap level pot.
If I were building one, I would like centre-detented level pots, but the statement that centre-tapped are mandatory, is not the case.
For me, the awkward requirement is the triple-gang frequency pots for the top and bottom shelving, as opposed to unbalancing the 2 integrators of the SVF.
Its beauty, though is its flexibilty; it is eminently hackable.
My 2p's worth.
Yes. It was said, that without center-tap the unit wouldn't work properly. That's what made me doubt. Seems like it's not the case. BUT if i had a little more cash right now, i would definitely go for switches. Anyway, thanks for your comment.
 
Last edited:

Gold

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I think I said I was surprised it worked without the center tap pots. I am no circuit designer and i never tried it without center tapped pots. To get the sections going i used two 5K resistors with a lead to ground to simulate the center tapped pot on the schematic. Then with another lead I could either get maximum or minimum gain. That works in the absence of a center tapped pot and without committing to a rotary switch. That was the context in which I made the commment.
 

porkyc

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I think I said I was surprised it worked without the center tap pots. I am no circuit designer and i never tried it without center tapped pots. To get the sections going i used two 5K resistors with a lead to ground to simulate the center tapped pot on the schematic. Then with another lead I could either get maximum or minimum gain. That works in the absence of a center tapped pot and without committing to a rotary switch. That was the context in which I made the commment.
Forgive me, I was not having a dig at anybody, (I hadn't read half the posts, anyway!) just that on BP's schematic it mandates centre-tapped level pots, and it needn't.
That is not to say it would not be better to use CT pots, but their absence/unavailabilty does not preclude the EQ from working. (Which is the implication).
Again, my apologies if anybody was put out by my comments.
 

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