8 Channel, 3U NEVE 1073 completed

[mitsos]

As 3nity pointed out, look for an engraver locally. They do CNC, sometimes laser and can usually work with Corel files.  Get a piece of anodized aluminum, let's say black, then put some kind of clear sticker on the engrave side (ask the engraver what would work with their machine, you don't want the laser to melt the whole thing) so that they engrave through the sticker. When you get it back, take some white paint to the sticker-covered faceplate, let it dry, then peel off the sticker. What you should have left is an engraved panel with inlaid paint. Since the paint is in the grooves, it shouldn't rub off with use and should be a heck of a lot cheaper than FPE. Haven't tried it but I think someone did this with Chae's service (white market). Now that I think of it, depending where you live, Chae may be able to do this cheaper.

 

[desol]

Thanks for the advice. I gotta find some other solution for this cause yes, it's just way too expensive.

 

[madriaanse]

Yeah FPE is pretty $$$. I would also recommend Chae Ham's services here on Prodigy Pro. I checked with him a while ago; he is very reasonably priced, and his work looks great: http://www.groupdiy.com/index.php?topic=27917.0

Best,

M.

 

[desol]

Thanks Martin(and Mitso)...I'll contact Chae. I also like the idea about the sticker.

I fired up a channel the other day and was blown away. My API's are great too...punchy lows, etc.
They both have that top end shimmer...but it's hard to believe the the N*ve bottom end...it's bigger and more complex or something. Hard to describe. Bigger overall. Awesome sound.

Definately different than the API. Both great...

D.

 

[madriaanse]

Hi Desol,

That's really cool to hear; I am glad you like!! IMHO, they seem to be a very good pairing for digital recording. The 1290's really help smooth over and "fill out" the sharp, vacuous sound resulting from A/D conversion. Another project that I think does the same thing (and then some) is Drip's LA-2A w/ original iron - just stunning on bass and vocs.

Best!!

M.

 

[desol]

Martin, i wanted to point this out too regarding our frontpanel discussions above.

http://www.groupdiy.com/index.php?topic=33694.0

Cheers,

Darrick

 

[djn111]

If possible I am interested in two PCB's

 

[kambo]

if you do line in only version, i take 8

if more people interested....  may be open a new thread for this.

kam

 

[kambo]

Ah, great reply Colin!! Digikey UK also has the BC184C's and 2N3055's btw, so you can one-stop shop.

Skal1, if you just need a LINE-IN module only, I'd do the following:
1) buy: CA-18-VTB9046 from www.audiomaintenance.com
2) buy: 71BD30-01-1-AJN (but preferably -AJS if in stock) from Digikey
3) leave the second pre-stage empty on the EZ1290 (closest to switch), and leave off the onboard rotary switch and surrounding resistors
4) point to point wire according to "Neve EH10023" - that's R1, R7, R9, R24, R25, R26, R27, R28, T2, C6 on www.technicalaudio.com/neve/neve_pdf/1073-fullpak.pdf (page 2). You'd connect to "U" of the first pre-stage, which on the PCB is to the right of the horizontal 18K resistor near the bottom.
The switch should be very simple to wire up because there's only one deck/pole and 7 positions; you'll also want to "stop-pin" it after the 7th position.

As I've said before, if there's enough demand it would be easy for me to do a line-in version of the EZ1290, but so far almost everyone wants a mic pre. The point to point work described above is really so pedestrian it's hardly worth sticking the rotary on the PCB. Different story for the mic-pre however.

Enjoy the preamps Sam!!!

M.

thank you for this tip.

is this correct...not sure about the 0V connection!

typo EDIT :  meant shielded cable on diagram

 

[echotodd]

Martin,

Just wanted to thank you again for the PCBs.  Two more completed 1290s entered the world over the weekend.  I let them burn in for a bit, biased them, plugged a mic in and smiled.  Very nice indeed!

Todd

 

[madriaanse]

Thank you Todd!! Great job, and enjoy!!

Kambo, your diagram is correct. However, if you can wait a week or two; I am awaiting a shipment of 1073 line-in PCB's, and should have them shortly. Once I test them and all works out well, I'll make them available to the board. I made these boards because I needed a good front end for a 16ch. line mixer I'm building.

Best,

M.

 

[wolfgang]

I am awaiting a shipment of 1073 line-in PCB's, and should have them shortly. Once I test them and all works out well, I'll make them available to the board. I made these boards because I needed a good front end for a 16ch. line mixer I'm building.

Thats great news!!!!!

Will this be line-in only or switchable line/mic?

greetings and good luck for this project!!!
Wolfgang

 

[kambo]

i am a very happy man.

if only line input i take 8

thank you
kam

 

[madriaanse]

Thanks Guys! They will be line-in only. I'll start a new thread once everything's been thoroughly tested and checks out perfect.

Best,

m.

 

[guidoz]

Thanks Guys! They will be line-in only. I'll start a new thread once everything's been thoroughly tested and checks out perfect.

Best,

m.

Great..!.sounds veery interesting..

 

[solderspongebob]

Hi madriaanse,

Wonder if you could have a quick look at the figures below please - these are the transistor voltages on an EZ1290 I'm trying to get working:

TR	C	B	E
1	2.252	0.942	0.378
2	23.44	2.233	1.678
3	23.44	1.678	1.117
4a	3.755	2.370	1.821
4b	3.769	2.376	1.823
5a	12.25	3.755	3.153
5b	12.29	3.767	3.169
6a	20.64	12.25	11.64
6b	20.66	12.29	11.67

(where 4/5/6 a are in the 1st gain stage, and 4/5/6 b are in the 2nd gain stage - transistor numbering and voltages refer to this document: http://www.musiciansgig.com/ez1290/transistor_voltages.pdf)

I'm a little concerned about the figures shown in red as they are a bit off from the measurements in your document, although the above figures are taken with the input and output transformers connected, but no signal present; oh and supply rail at +24.05V.

Problem is I'm getting barely any output - very low level and distorted. If I turn up full gain with a microphone connected then it starts to smoke a little around the output stage  (couldn't locate what was smoking and nothing looked charred!).

I have two sets of transformers and two boards built up - both exhibit the same behaviour. I've checked PSU and all is good; phantom power to mic is ~49V, so OK there too. I've also swapped transformers between boards with no difference. Would disconnecting the transformers and ohming the coils prove they are working? (I'm not sure what measurement to expect as I'd be measuring resistance and not impedance - advice welcome).

Any ideas? I think something simple is wrong here and I'm going to publicly end up wearing the dunce hat for a week afterwards 

Any help appreciated.

 

[desol]

Just wondering if anyone has built these with the conductive plastic pots mentioned earlier and what their experience has been?

Thanks.

 

[madriaanse]

Hi Soldersponge,

Sorry for the delayed response. Take a real close look at R3 (68K), R6 (18k), R7 (47R) - are they the right values? You're probably smoking R7. Also, see if you can adjust the trimpot so that you see about 22V on the TR3 collector.

M.

 

[solderspongebob]

Hi madriaanse,

Thanks for the suggestions - I will double check those values those later today and also get the oscilloscope out and trim the bias.

The good news is that I got the preamp working last night after re-writing my connections to the transformers; I couldn't see anything wrong with the wiring before, but re-did it anyway and now it works!

Also, the output transistor barely got warm and there was no smoking this time!!! 

I did initially think I had a problem with a buzzing noise, but after a couple of minutes I found the cause - it was my temperature controlled soldering iron!!!    Once I switched it off, there was no more buzzing - I guess it just uses a similar circuit to a dimmer switch and was after all right next to the circuit I was testing. Just goes to show...

Now to wire up and check out the 2nd preamp.

Many thanks madriaanse!

 

[madriaanse]

Great!! It sounds like you may have had a cold solder joint. Also, make sure the 12R and 270R are the correct values.

Speaking of cold solder joints, the new EZ1290 V2.2 boards will have bigger .080" solder pads, and are even more "EZ" to solder. (my apologies for the lame pun)

Best,

m.