8 Channel, 3U NEVE 1073 completed

[ElectricApe]

Here are some build progress pics of my 8ch mic pre:

http://www.musiciansgig.com/neeb/

It is almost finished; I just need to hook up the power supply. All channels have been tested, biased and are working as they should individually. Carnhill VTB9045, 9049 for I/O. The PCB's you're seeing are the EZ1290 pcb's that feature two pre stages, a driver stage, rotary switch, and all the other decoupling caps, resistors to make a 1290/1073.

This project has been a TON of work and in hindsight I probably would have built two 4ch, 2U units. Either way it has given me a lot of respect for the people who build consoles and modules.

Sorry for the grainy pics :green:

M.

----------------
EDIT:

I wanted to consolidate all the build info for these preamps here, see below:

Here is a complete BOM:
http://www.musiciansgig.com/ez1290/1290BOM.xls

Assembly guide:
http://www.musiciansgig.com/ez1290/assembly.pdf

Transistor voltages for troubleshooting:
http://www.musiciansgig.com/ez1290/transistor_voltages.pdf

To connect a trimmer to these boards, see:
http://www.musiciansgig.com/ez1290/trimmer_v2.1.pdf

Front Panel Design for 2U, 2ch:
http://www.musiciansgig.com/ez1290/circuit_specialists_2u_panel.fpd
(to open this file, you need Front Panel Designer. Free download from: http://www.frontpanelexpress.com/)

I´m new to this forum - hello everyone. I hava a question, does anybody know how much much cash this BOM takes ?

Glad for any hints, thank you.

 

[mmmyesm]

pg 2, reply #37.

 

[snipsnip]

Hi snipsnip, any luck sorting out the problem?

M.

Hi mate,

no luck yet. To complicate matters, I blew up my PSU when I first built it because I shorted the lm317 tab to the case. The board itself was quite damaged from the heat. I managed to frankenstein something together, but it seems the power is oscillating occasionally (damaged voltage reg?)... this means I cant really take readings from the TR3 for you at the moment.

I need to fix the PSU issue before following up on the other issue. Will try and hit you up for more advice soon though!!  ;D

Thanks for your help so far.
Jake

 

[Whoops]

Hi snipsnip, any luck sorting out the problem?

M.

Hi mate,

no luck yet. To complicate matters, I blew up my PSU when I first built it because I shorted the lm317 tab to the case. The board itself was quite damaged from the heat. I managed to frankenstein something together, but it seems the power is oscillating occasionally (damaged voltage reg?)... this means I cant really take readings from the TR3 for you at the moment.

I need to fix the PSU issue before following up on the other issue. Will try and hit you up for more advice soon though!!  ;D

Thanks for your help so far.
Jake

Maybe Doing a new PSU that you can tottally rely on???

 

[madriaanse]

1) Is there a preference for a particular make of 2N3005? Motorola or ST or On or something else?

Some people say they prefer the Motorola's. I haven't done any comparisons, but I will state the preamp sounds stunning with the ST Micro version.

2) Is there a preferable Hfe range for BC184Cs and 2N3055?

Yes, there is. I think Neve spec'd to use BC184's with HFE of 600 or higher, this would be especially for TR2. I haven't bothered with it. Noise hasn't been a problem with these and if I'm recording really quiet source I use GML.

3) Does the Grayhill switch chosen for this project -that AudioMaintenance sells- have an adjustable stop to prevent it from going around the clock?

Yes, if you insert the stop pin at 12 o'clock it will not allow you to switch from 70 to 20 dB or vice versa - a very good feature indeed!

Also some of the Digi-Key codes in the BOM seem to lead to an irrelevand part number, so it would be good to check them just to make sure.

Thanks for the heads up. Which part #'s?

M.

 

[madriaanse]

Hi mate,

no luck yet. To complicate matters, I blew up my PSU when I first built it because I shorted the lm317 tab to the case. The board itself was quite damaged from the heat. I managed to frankenstein something together, but it seems the power is oscillating occasionally (damaged voltage reg?)... this means I cant really take readings from the TR3 for you at the moment.

I need to fix the PSU issue before following up on the other issue. Will try and hit you up for more advice soon though!!  ;D

What PSU are you using? It's strange the LM317's "blow" like that - I've done that myself. I thought they were supposed to crowbar during shorts? You'll probably want to replace the 10R, the diodes and LM317.

M.

 

[snipsnip]

Hi mate,

no luck yet. To complicate matters, I blew up my PSU when I first built it because I shorted the lm317 tab to the case. The board itself was quite damaged from the heat. I managed to frankenstein something together, but it seems the power is oscillating occasionally (damaged voltage reg?)... this means I cant really take readings from the TR3 for you at the moment.

I need to fix the PSU issue before following up on the other issue. Will try and hit you up for more advice soon though!!  ;D

What PSU are you using? It's strange the LM317's "blow" like that - I've done that myself. I thought they were supposed to crowbar during shorts? You'll probably want to replace the 10R, the diodes and LM317.

M.

Hi, Im using the JLM Audio ACDC v2

The voltage reg didnt 'blow', but i replaced it anyway. The 10u caps nearest the 48v LM317 blew up and the 10r and 47r completely burned out.

I replaced the 317 as a precaution. So you think I should change the diodes too? Board is falling to bits so i think I better get a new one (sigh) thinking long term.

As soon as I get a stable PSU I'll give you the DC reading from TR3, and LO1166.

Ive also just ordered a scope, so this should maybe help?

Cheers!

 

[vitopower]

PCB arrived right away, looks great!  Warming up the iron.  Thanks, Martin!

 

[snipsnip]

Hi Martin,

Im building a new PSU, but I swapped out a voltage reg as a temp fix and managed to get it outputting a solid 23.5v for some tests.

Do these results mean anything to you?


TR3

C: 0.5
C: 0.5
B: 0.5
E: 0.0

The readings on LO1166 are
1: 0.5
2: 0.5
3: 23.5
4: 0.5

Just as a recap, my TR4, 5 & 6’s are all measuring OK, but my TR1 & 2’s measure as follows:

1)
C - 1.2
B - 0.0
E - 0.0

2)
C - 0.5
B - 1.2
E - 0.5

My scope has arrived, but its at my friends house. But I can get it at any point next week if you need me to do any further diagnostics.
Thanks a lot!
Jake

 

[SIXTYNINER]

HI madriaanse
interested about this project you made....
please , is possible add a DI input for gtr & bass
to this preamp?
thanks in advance
cheers
6t9r

 

[madriaanse]

Do these results mean anything to you?

TR3
C: 0.5
B: 0.5
E: 0.0

The readings on LO1166 are
1: 0.5
2: 0.5
3: 23.5
4: 0.5

Hello,

It seems something's not right with your LO1166. 23.5V on pin 3 is correct, but pin 4 and 2 should be about .3 volts lower than pin 3, and again, pin 1 should be about .3 volts lower than pin 2 and 4.

M.

 

[SaMpLeGoD]

Hello Martin, how are you?! I tried to PM you, but your mailbox is full...  :-\
I'm writing you to ask if you have some EZ1290 boards available, and how much can it coast with the shipping to Portugal!
Thanks a lot for this awesome project!!

Cheers,

Eddie

 

[snipsnip]

Do these results mean anything to you?

TR3
C: 0.5
B: 0.5
E: 0.0

The readings on LO1166 are
1: 0.5
2: 0.5
3: 23.5
4: 0.5

Hello,

It seems something's not right with your LO1166. 23.5V on pin 3 is correct, but pin 4 and 2 should be about .3 volts lower than pin 3, and again, pin 1 should be about .3 volts lower than pin 2 and 4.

M.

Thanks for your thoughts martin.

I think you are correct! If I put the non working channel to the working lo1166, the voltages all come up correctly.

If I put the working channel to the bum transformer then the voltages drop to the reading previously displayed on the broken channel. I think we can safely say there is an issue with the transformer. I checked for continuity between all the wring & jumpers and its set up correctly, so I will send it back for testing.

However, even with the correct voltages, im getting no sound!

I'll try and trace the audio with the scope and see where its dissapearing.

Cheers!

 

[snipsnip]

Well, i traced the audio with the scope all the way up to the transformer, then i remembered I had changed my routing last night!!!

We have sound. The answer was a bum lo1166. The last thing i expected!!

Thanks for all your help martin! you're a legend!  ;D

 

[madriaanse]

Congrats and good work!! I hope you get to enjoy them for many session to come!

M.

 

[snipsnip]

Hi Martin,

Really sorry to bother you again.....


Ive got a new problem.. when I turn the gain up to 50 and beyond, all I get is a very high pitched irregular hissing noise. No audio at all.

Do you have any idea what may cause this?

Thanks a lot!
Jake

 

[Carlos Lima]

Sorry to interrupt the topic.  :-[

There is still PCB's available?

Thanks.

Carlos

 

[madriaanse]

Ive got a new problem.. when I turn the gain up to 50 and beyond, all I get is a very high pitched irregular hissing noise. No audio at all.

Do you have any idea what may cause this?

Hi Snipsnip, yes that sounds like oscillation. This is usually caused by:
A. not using shielded wire
B. running mic input wires too close to line output wires
C. having the 10468 (VTB9045) too close to LO1166 (VTB9049)
D. malfunctioning 2N3055

Also, double, triple, quadruple check the resistors values around the gain switch.

Hope this helps,

M.

PS. (for Carlos Lima) email me if you're interested in PCB's: martin_adriaanse (at) yahoo (dot) com

 

[snipsnip]

Martin, Thanks so much for this, I  will look into all these things and update you. I might upload a pic of my layout to show you how close my ins and outs are.. I thought they would be OK as there is a bit more of a gap than in your 8 channel monster! 

BTW - the noise is coming from the transformer, as when i have no source plugged in and no output hooked up, I can hear the same noise coming from the LO1166 itself if I crank the gain.

 

[1954U1]

Hi Martin,
received the EZ1290 PCBs, great stuff, thanks for doing that