ten81 EQ help please.

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ChuckD

Well-known member
Joined
Jun 3, 2004
Messages
578
Location
Irvine California USA
Ok I am just wrapping my brain aroung the EQ section of the Neve 1081. Can some explain it to me in greater detail?

From the ten81 project I have the BOM which lists the following:


==========================================
SW2 Trebble 3 Pole x 6 Position Rotary Shorting
SW3 Hi-Mid 1 Pole x 11 Position Rotary Non-Shorting
SW6 Lo-Mid 1 Pole x 11 Position Rotary Non-Shorting
SW8 Bass 3 Pole x 6 Position Rotary Non-Shorting
SW9 Hi Filter 3 Pole x 6 Position Rotary Non-Shorting
SW9 Lo Filter 3 Pole x 6 Position Rotary Non-Shorting
Output Fader 10K Log Pot
SW1 Shelving SPDT
SW4 HI-Q SPDT
SW5 HI-Q SPDT
===================================

The Neve sites list this:

HF peak / dip or shelving switch
HF at: 15, 10, 6.8, 4.7, 3.3kHz and off
HMF at: 8.2, 5.6, 4.7, 3.9, 3.3, 2.7, 2.2, 1.8, 1.5kHz and off
HMF bandwidth switch
LMF bandwidth switch
LMF at: 1200, 1000, 820, 680, 560, 470, 390, 330, 270, 220Hz and off
LF peak / dip or shelving switch
LF at: 300, 180, 100, 56, 33 and off
HPF: 27, 47, 82, 150, 270 Hz and off
LPF: 15k, 12k, 8.7k, 5.6k, 3.9kHz and off

=========================================


1. These don't seem to match up on the last two switches, as the orignal had a 2-in-one rotary didn't it?

2. And why do we need 3 Pole swicthes for the 6 Position ones?

Can someone shed some light on this for me? Thanks! I don't own one of these and have never used an orginal 1081.


Parts info: I have found Electroswitch carries the following:

E5G0323N 3pole 23positions shaft_lenght=1/2" or 2/8"
D1G0312N 3pole 12postions Non-short
D1G0312S 3pole 12postions Short

Anyone else find these somewhere that is "in-stock"?

-ChuckD
 
I've been wondering the same thing.

I know there is a group order pending for authentic switches and knobs, but I was also wondering if anyone has gone ahead with substitute parts.
 
I don't quite get what doesn't watch up with the last 2 switches :? The original used concentric devices all through. You need 3 poles because of the way the switche(s) is built up. If you peep an original pic, you'll see that some switches have 3 wafers (poles) x 6 position function.

I haven't heard from anyone who has completed the project. There were a couple of serious builds going on a while ago but I'm not sure of the outcome. There were some issues worked out because of the builds but nothing due to the pc boards (other than silk screen) but rather the literature and/or parts list. This is an expensive build so I'm sure it'll be a while before someone completes it. I had to put this project on the back burner for myself because of other priorities but I am still collecting parts along the way.
 
Doesn't that mean:

6 postion
3 Decks
1pole per deck?

Then maybe this part will do: 12 positions though.
Electroswitch (mouser) C4D0312N

=============

What does concentric device mean?
When I look at the picture of 1081s I see 5 EQ knobs. The last one appears to have both the HPF and LPF with a dual dial.


http://www.audio-toyshop.co.uk/Tech_Archive/Neve_history_2/Neve_1081/neve_1081.html


Where do I get a switch like this?

-ChuckD
 
I was gung ho on this but put it on the back burner until the documentation got updated and sorted out. I think a new rev. on the docs would be a motivator, but right now the forssell limiter project has my full attention. A schematic for the 1081s that matches the boards would be really helpful, I like to follow a schem while I stuff just to (hopefully) head off any problems.

dave
 
I have about ten or fifteen pages of old Neve eq stuff scanned, but the darn files came out so huge.
If anybody wants to see if they can shrink without too much lose, you are welcome to try.

neve_switch.jpg
 
The high and low switch are special switches!
Low is cumulatively un-shorting and high cumulatively shorting! For the low freq this means that in the lowest position all positions is connected to the waffer then it extracts one for each position, all caps are in parallell in the lowest position. High switch works in opposit way since it starts with the highest freq and then add caps for each freq.
With a normal switch you'll end up with BIG and uncommon values for the caps!

I'm sure that some english speaking person will explain this in a better way
 
Blimey, this is a coincidence.
Blake FINALLY got back to me today (he had a good excuse though)
The switches and knobs group order should be back on soon, I will post within five days at the black market. The group order is still open if you want to add to it.

Thanks for your patience!!
 
You can see what concentric means by the pic that cj posted. It's a device (pot or switch) that mounts to and the shaft comes through another device so they both can be controlled...good to use when space is an issue. You can use a 12 position switch as long as you stop it at 6 positions.

I am going to get the documentation to another rev soon but as I said, it's on the back burnner for now. I have some schems that reflect the silk screen and so on but just need to organize it all.
 
Thanks for the explaination Tom.

Yes I probably want to get in on that group order of the switches. When priceing out the switches on Mouser theey seem to be very expensive.

Do you know how much and what the turn-around time is going to be?
I really want to order all of my parts soon.

I am still a little forry on how that last switch functions so if someone can better explain it please do!!

-ChuckD
 
ChuckD said:
Thanks for the explaination Tom.

Yes I probably want to get in on that group order of the switches. When priceing out the switches on Mouser theey seem to be very expensive.

Do you know how much and what the turn-around time is going to be?
I really want to order all of my parts soon.

I am still a little forry on how that last switch functions so if someone can better explain it please do!!

-ChuckD
hello chuck
i think that it's time to re-design the ba 312
for give to the eq switches connections
a new modern layout that let to place new nice "grayhill" gold plated rotary switches
as done for 1072 input gain by seventh circle audio
and make much easy the rotary switches placement/wiring
what you think about?

someone want give a bit of help about?
6T9R
 
i 'd like to help out here. next couple of days will see me stuffing my b312s. i got thru the opamp boards. checking really carefully as i went that what i was stuffing equaled my neve circuit and the layout rev7. it was all good.. i hope. im going to make a test rig to fire all those amps up before plugging into b312. and then comes the switches ..... mine are in transit to NZ i believe. so im eager for any good info about the switches.

the documentation has been a bit confusing with all the opposite component numbering carry on. but between the layout pictures of rev 7 and the neve circuit for values. itll work out. on b312 so far ive notice quite a few changes in info rev7  from the neve circuit. changes that have have had something to do with the made up inductors dc resistance or eq circuit impedance or something. i decided to stick with original - and make it easy to change/experiment with those bits later on. to document all the differences while im stuffing .

can anyone comment of the rev 7 changes to clarify why they were made . theres a component completely missing too. ... i think?i gotta check again when im in there.

back in november tommy tones said he would have a new schem to go with the rev 3 boards.
any news there? ...
anyway its actually all good.
 
EKADEK said:
the documentation has been a bit confusing with all the opposite component numbering carry on...
can anyone comment of the rev 7 changes to clarify why they were made . theres a component completely missing too. ...
back in november tommy tones said he would have a new schem to go with the rev 3 boards.
any news there? ...
anyway its actually all good.

+1 !!
 
ive found one definite big difference in the rev7  layout.

here is the rev7 layout that ive been looking at to guide me where components go.

http://www.nrgrecording.de/html/neve1081.html


reading  the 312 diagram u see the op amp A5 driving out thru a 15k to the next stage (op amp A7) shunted by the equalising effects of the bass switch assembly. well i couldnt see that 15 k on the rev7 layout  but traced it thru and there it was. the spot where that 15k should be with a dirty great  6M8  in its the place.  where should be a 15K for the circuit to look alright to itself.. 

the component spot  is  printed as R74 on the  312 rev 3 board i am stuffing (hopefully not  up.)

maybe thats why those inductor feeding resistors in the two previous eq stages were altered... hmmm  ... to counteract the effects of an unseen and incorrect equaliser balancing resistor in that last equaliser stage. or just too much solder fumes maybe.

anyway if someone else would be able to check that .  or is it old news. 
 
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