Do It Yourself Neve 1073

[Neve1073lover]

The Main Board

I used greencaps mainly becuase I could not get the correct polyester caps.

I did not use any ceramic capacitors on the main board as they are shit. I use one only on an input transformer as it was the only way to get the correct value.

Try and use greencap or mylar as a minimum.

Most small electrolytics were either 16V or 25V. Use either.

There are some electrolytic values I could not get. 80uF 25V was one of them.

Get a 33uF and a 47uF both 25V and wire them in parallel (+ to + , and - to -). Caps add together in parallel.

There are 3 errors on Linear-Recordings 'Stuffed' pdf. I will show them in my next post.

 

[Neve1073lover]

Looks liike I have lost a day's worth of work...

May take a while to get motivated again.

Hope there was an incremental backup or raid that can be recovered from.

 

[Chili]

Looks liike I have lost a day's worth of work...

May take a while to get motivated again.

Hope there was an incremental backup or raid that can be recovered from.

Looks like the whole board did a time-warp.

 

[Neve1073lover]

The Three Errors

Lost this and posting again...

Other than the error in using 10x the cap values in the power smoothing, there are three other errors in the 'Stuffed' PDF.

The pcb main board design is good, but the 'Stuffed' overlay has the errors. It also looks like it is based on an earlier design of the pcb.

Where are they:

Error 1:

This is what the stuffed overlay shows:

The 1k5 resister should be as shown here:

Error 2:

There is a missing 220k resister (shown as R1 here) that should be on the BA211 board area:

Error 3:

This is more complex.
This is what the stuffed overlay says:

This is what the pcb board looks like:

This is my interpretation of the intent:

C1 is the 22uF/16V cap that is shown on overlay.
C2 is a 22uF/16V cap that is denoted as C11 on page EH10023 of the schematic.
R3 is the 18k resister shown on the overlay.
R2 is the 51k resister shown on the overlay.
R1 is a 2k7 resister denoted as R58 on page EH10023 of the schematic.
L1 goes to the left as per the overlay.
L2 goes to a 39k resister (denoted as R72 on page EH10023 of the schematic) and then to the board's 'earth' pad (on the left, the large copper area).
L3 goes to the EQ switch.

Hope this does not get lost again....

 

[Neve1073lover]

PCB Daughterboards

Here is a shot of the pcb that holds the resisters used in the gang switch at S2b:

These are the two inductor boards:

The 1950 replaces the Sowter T1530 and the 9043 replaces the T1295

The Carnhill 9044 inductor actually will fit into the Sowter T1280 location.

Here are pics of the boards (happy to give away, PM me):

This is what I ordered from Carnhill and the UK prices:

Shopping Cart (Prices in British Pounds)
DESCRIPTION QUANTITY PRICE COST
----------------------------------------------------------------------
CA-18-VTB9043 - Inductor: 1 £17.09 £17.09
Audio signal - Multi-Tapped
(Line level)

CA-18-VTB9044 - Inductor: 1 £15.09 £15.09
Audio signal - Multi-Tapped
(Line level)

CA-18-VTB9050 - Inductor: 1 £15.09 £15.09
Audio signal - Multi-Tapped
(Line level)

CA-18-VTB9045 - Transformer: 1 £39.18 £39.18
Audio Input (Microphone
Level)

CA-18-VTB9046 - Transformer: 1 £43.74 £43.74
Audio Input (Line Level)

CA-18-VTB1148 - Transformer: 1 £17.66 £17.66
Audio Output (Narrow Board
Version) ======================================================================
Subtotal: £147.85
Shipping (Airmail - Outside Europe): £13.95
Total: £161.80

 

[Neve1073lover]

The Power Supply and RU2 Rack

Happy that people can do their own thing and try and get a 'better' clone by copying the Neve power supply design - I believe that the inductors and audio transformers make a bigger impact.

Found the 24V PS at Jaycar and decided to use it. Cannot fault it. $75 Aus.
I can give the specs and part numbers if you want them.

Also got the 2RU rack at Jaycar (did not end up using the 240/24V transformer shown):

Garry

 

[Neve1073lover]

The 2N3055 Transistor and Fins

I could not find a smaller cooling fin than that shown in the previous post.

I needed to cut off 2 sides to make room for some electrolytic caps and resistors.

It actually sits over some parts, so I:

Mounted a mylar insulator and 'pin' insulators under the resistor and bolted it to the cooling fins with nuts that were thick enough to make it clear the parts underneath. After all the underneath parts were installed and checked, bolted the whole lot onto the board (the bolts were long enough to take the nuts, go through the board, and then get nuts on underneath.

Then soldered the 2 transistor connections. The third is the case that is connected via a bolt.

 

[Neve1073lover]

Conencting the Boards

I soldered individual wires between the 'switch' board and the main board.

I held the wires and my son mostly burnt me as he soldered. If you put all of the wires onto the switch board, so they come straight up from the connections, you can then put individual shrink wrap over every on by sliding it over the wires and down onto the pins.

These wires then go down under the switch board and up to the pins on the main board. Done this way, you can again put individual shrinkwrap on each pin.

A test fit of the boards:

 

[Neve1073lover]

Knobs and Switches

I used the knobs with the white ends (see prev post) as the ends come off and can point in any direction. Got them from Jaycar. The switch board is designed with the switches rotated in some funny directions so you need this feature.

The EQ and Phase square, pushbutton, latching, switches I bought from Mouser. Son wanted square white switches that could have the labels inserted under the clear top. Printed label signs onto plastic overhead projector foils on laser printer.
'Teaser' on the Front Panel design.

The switches actually attach to the front panel. They can be pulled apart so that the outer capsule can be bolted to the front panel and the actual switch can then be clipped on the back.

 

[Neve1073lover]

The Input and Output Audio Transformers

I had trouble understanding some of the very old schematic symbolism.
Thought I would share what I found out.

The Mic Input Transformer:

T.P is Test Point. Ignore.

All transformer tap numbers match the Carnhill numbering.
The DPDT switch (HI/LO) allows you to match the Mic impedence.
As shown, it connects pins 4 and 3, making it a HI impedence input. This makes for a longer coil that has pin 2 as the active and pin 5 as the neutral.

When you switch to LO, it creates two transformer windings in parallel (winding 2-4 is in parallel to winding 3-5). Resistance in parallel makes for a lower resistance.

At the number '3' on the schematic, you may wonder what has happened to the wire that comes from output 10?
This is how a shielded wire is denoted. It is using the core of the wire to connect '7' to the switch. The outer shield of the wire connects 10 to the wire between R10 and R11.

 

[Neve1073lover]

The Line Input Transformer Schematic

At the 'T1' point, the wire is a 2-core shielded audio cable.
H is the active (red colour usually) and goes through the wire shielding and is connected to 5.
F is the neutral (white colour usually) and also goes through the wire shielding and is connected to 2.
Y is the actual shield that is earthed to the board.

The '.' dots are phase dots that ensure that you get the transformer input and output phasing correct. If you connect to the correct numbers on the transformer, you can ignore.

At 'T2' is a different representation of a shielded wire.

 

[Neve1073lover]

The Output Transformer Connection

You should have the idea by now.

Wires at '8' and '9' are two core (red and white), shielded audio wire.

The shields are earthed AT ONE END ONLY.....

 

[Neve1073lover]

Transformer Photos

I did not use shielded wire everywhere. Make it how you want to.

The left hand trans is the mic, the RH is the line. You can also see how I connected the 24V power on the lower left.

Below is the output trans:

 

[Neve1073lover]

The Front Panel

I designed my own Front Panel using 'Front Panel Express' free software.
Actually very simple to use software and gives you a running purchase cost.

If you use this design (PM me), get the panel made and THEN use it to mark where the holes go on the 2RU front panel.

The pots ,3 gang, and circular switches bolt to the rack's panel and then go through holes in the front panel.

The pushbuttons and the VU meter mount on the front panel.

Therefore I cut the RHS of the rack's front panel off just to the right of where the middle attaches to the rack.

The rack panel itself can be slid back and forwards slightly and then screwed in to get it as close as possible to the 'real' front panel. You may need to drill out the holes slightly on the 'real' front panel to allow the 3 gang switch to get far enough through to get a knob onto it.

The Front Panel IN ALL ITS GLORY.........

My own 'Neve 1073' brand:

 

[Neve1073lover]

Feedback Please

What more do you want to know?

Am I hitting the right level of explanation?

What do you think?

 

[Chili]

What more do you want to know?

Am I hitting the right level of explanation?

What do you think?

Very nice. It will take a while to look at everything in detail. I might have missed it, but does this unit have phantom power?

How long did it take to complete the project?
How much would you estimate you spent on it?
Do you have any audio clips?
It looks like the chassis has lots of room for another channel, but what about teh front panel; do you think it can be arranged to accommodate twice the switches, etc.?

Thanks for posting this!!

 

[Neve1073lover]

Very nice. It will take a while to look at everything in detail. I might have missed it, but does this unit have phantom power?

How long did it take to complete the project?
How much would you estimate you spent on it?
Do you have any audio clips?
It looks like the chassis has lots of room for another channel, but what about teh front panel; do you think it can be arranged to accommodate twice the switches, etc.?

Thanks for posting this!!

No phantom power.
Took about 6 months to get all of the parts together and built. Many of the cap values were hard to find..
I have spent less than $1,000 AUS on it.
I will get some audio clips off my son when I can
Linear-Recording put two of these into a single 2RU rack. Leave out the VU meter and get smaller gang switches, mount the transformers on the vertical sides of the rack and you can just fit two in. I would also get a 4 gang switch and remove the resistor board to make more room.

The panel can be rearranged to fit two. I will give the soft copy of the design and people can use the 'Front Panel Express' software to rearrange as they see fit.

 

[mshilarious]

Happy that people can do their own thing and try and get a 'better' clone by copying the Neve power supply design - I believe that the inductors and audio transformers make a bigger impact.

Found the 24V PS at Jaycar and decided to use it. Cannot fault it. $75 Aus.
I can give the specs and part numbers if you want them.

That's a switching supply, is it not? I would guess the Neve purists would not accept it; it's far too efficient!

At the same time, I wonder why nobody scales back the bias current on the output transistor and uses a lower ratio output transformer. Especially for those feeding a converter; +30dBu headroom doesn't do a lot except waste a lot of power. But then I am a heretic too!

 

[Neve1073lover]

That's a switching supply, is it not? I would guess the Neve purists would not accept it; it's far too efficient!

Yep a switching supply. Small footprint and very clean power. If you want to have any effect from power 'sag' etc, then don't go this way.

 

[mshilarious]

Yep a switching supply. Small footprint and very clean power. If you want to have any effect from power 'sag' etc, then don't go this way.

Certainly if you are building a bunch that's the way to go; put it in a separate case and route low-voltage supply lines to them. The only concern is that, as we learned from the Chinese clone experience, the Neve circuit has poor PSRR, so a good quiet supply is indicated. A typical PC supply need not apply (wrong voltages anyway), but I have also found that a quality commercial switching supply is tough to beat.

That said, I'd probably scope its output just to be sure . . .