8 Channel, 3U NEVE 1073 completed

Hi
Here is an email from Martin :

My understanding is that Neve used BC107/BC109/BC184 interchangeably. BC107 and BC109 have been replaced with BC547 and BC549C respectively. Using the EZ1290 layout from here:
http://s3.amazonaws.com/EZ1290/transistor_voltages.pdf

You can use:
BC549C for TR1, TR4
BC547 for TR2, TR5, TR6
2N3055 for TR3

Le Roux said:

Closer inspection last night reveals that my original fairchild's have the "f" then BB13 in small hard to read writing next to it, and the ones I ordered have the "f" with BA41 in small next to it.
I tested the hfe, and they averaged around 450, where as all 8 fairchilds I have tested around 300-350.

I do think they're good to go!

Click to expand...

Finally got mine too. It seems that they have different labelling on them, "BA12", "BA17", "BA35" and "BA41". I haven't tested them yet, but do anyone know what these different markings mean?

Does also anybody know why there hasn't been the 2200u 25V capacitor on the BOM?

Or has there been a change in value?

Such as C4, C6 & C7 (Capacitor Electrolytic 82uF 25V) which are maybe for this purpose and therefore deviate from the board's indicated 100?

*Edit* I simply chose 100uf 25v capacitors for the not corresponding 82uf and took the missing 2200u capacitors also into my cart. Wondering why it is not listed under the official metal BOM.

Anyways, what I'd still like to know is what it means to draw EH10023. I suppose this is a section of the board but nothing more? Does it have to be tapped (possibly by placing the 180uf capacitor there) in a way of modding it to deliver more gain? Didn't find a hint throughout all the thread's pages.

Hi All,

Finally got around to building this pre. I found a stock of BC184C at Future Electronics, OEMS Trade is great for sourcing hard to find parts. I have a problem with this build though. I have not gotten my Carhill Trafo's yet but had some old Neve's laying around.

Mic Input is Belclere TF10016
Output is Big Orange VT24499

Pre is passing signal and amplifying but I have a drastic difference (about 25dB) from 100Hz to 10kHz, with 1kHz in the middle. Frequency response is way off. I wouldn't think that the trafo's would cause this, but I could be mistaking. Let me know if anyone has any thoughts. Solder On!!

@atticmike, The first BOM on page 1 also uses the metal film resistors for the most part and has all the correct values.  Maybe go off that one instead?

I chose these for that purpose:

http://uk.mouser.com/ProductDetail/Nichicon/UKA1E222MHD/?qs=ZkXqA7GzKJJMuw8S3Hf38Q%3d%3d

http://uk.mouser.com/ProductDetail/Nichicon/UFW1E101MED/?qs=kArNe9LFxXmnkbKvib80gQ%3d%3d

Also noticed that you were all building external power supplies. What if I isolated the power-section with metal plates and anyhow, don't toroid transformer cause the least trouble in audio racks with the unit's transformers?

Depends on how many channels your going to build. Toroids are noisy...even to units
above and below in the rack. Placement and good grounding practices is everything.

I used some mu foil to add a litte extra shielding where needed.

desol said:

Depends on how many channels your going to build. Toroids are noisy...even to units
above and below in the rack. Placement and good grounding practices is everything.

I used some mu foil to add a litte extra shielding where needed.

Click to expand...

Gonna put two neves in the same box with two ssl 9k so it won't be that bad whereby there is another build with four apis in one box.

How for example would be the best placement of a toroid transformer? Horizontal or vertical?

I don't know, i think it's noisy either way. You can try looking on a scope or just listening and turning it to see what's best.
One of these probably wouldn't hurt: http://www.don-audio.com/trafo-shield

Make sure the inputs and transformers are shielded/placed properly and you won't have any problems.

desol said:

I don't know, i think it's noisy either way. You can try looking on a scope or just listening and turning it to see what's best.
One of these probably wouldn't hurt: http://www.don-audio.com/trafo-shield

Make sure the inputs and transformers are shielded/placed properly and you won't have any problems.

Click to expand...

Seriously? I mean aren't builds such as the 1176 also prone to such noise floors and still several people just put the transformers in the same enclosure?

What if I shielded every fucking thing that resembles a magnet as you said including the unit's transformers?

And about the grounding I shouldn't have to be worried since a put a lot of effort in grounding the shit out of my builds.

I'm just trying to be reasonable considering what people do with their other builds, including people that have also posted on this thread.

Well, i mean you wanna use de-facto carnhill inputs as they will be shielded properly. The rest is just common sense and experimentation.

I'm putting together a dual ez1290 in a 1u case. What length stand off did you guys(who used a 1u case) use in order to have the gain switch remain in the center. I assumed I should simply divide the 1.25" (2u case) in half to a .625" standoff. Advice?

That's the tough thing...exact measurements, to avoid unneeded stress on parts. Mine were installed vertically....so there were no feet. But for the things that i did need exact measurements for, i used a digital caliper...then checked...double checked...triple checked, quad, quint, etc....in reference to my frontpanel layout.

Time consuming, but it's worth it. Get as close as you can...then shim with plastic washers, etc...if needed.

Hey team,

is the only reason for not using BC184LCs the pinout? I was wondering cos, i have found a stash of them with HFE all around 650 and to rearrange the ECB to EBC is quite easy.

thanks for any help

Michael

I'm putting together a dual ez1290 in a 1u case. What length stand off did you guys(who used a 1u case) use in order to have the gain switch remain in the center. I assumed I should simply divide the 1.25" (2u case) in half to a .625" standoff. Advice?

Click to expand...

I'm not sure I understand correctly, but if you center the gain switch on the front panel the pcb won't be in the center, since the pcb mounts to the bottom of the switch. I think I used either 1/4" or 1/2" standoffs when I built mine.

I wasn't refer to the PCB as the center, I assumed 1.25 length used in the 2u to be relative and therefore the 1u case would require half the length at .625... Hmmm maybe

Best thing to do is created or draw a mock up on paper. Do you have the case already? You could use a caliper and take case measurements, draw them exactly on paper(drawing it like a sideview)....assume a standoff size...say 8mm, draw them in, then draw the pcb/switch and find out where it ends up on the frontpanel. That's where your switch hole, etc would go.

Adjust from there...

Got a question.. whats the input impedance for the pre (i have 6 of em and dont even know) the 1073 has a switchable impedance and i'd like to possibly mod mine to do that as well.

muffy1975 said:

Hey team,

is the only reason for not using BC184LCs the pinout?

Click to expand...

I recall reading somewhere that the pinout is the only issue. If the HFE is high enough, you should be fine.

I've just finished mine, and can't wait to test it on recording session.
You can find on the 4th reply a 48v/pad/pol pcb and an input transfo pcb for switching impedance.
Enjoy!
Another EZ1290