8 Channel, 3U NEVE 1073 completed

[Chrome Heart]

BTW, I would be using a shielded cable to carry the +24, +48 and 0V to the preamp. Looks like you have lamp cord in there.

 

[sr1200]

The screw can contact the case, as long as its well insulated (which it looks to be) and is not making contact with the metal part of the VR.  I was gonna say something about that cable as well... get yourself a 3 conductor shielded cable to run from the PS to the unit.

 

[Chrome Heart]

Yes. The screw should not come in direct contact with the case.

 

[Harpo]

i have a JLM power station that i am using to power 4 ez1290's.  i recently moved the power station from inside the chassis, to an external enclosure (at the same time, i switched to an avel lindberg toroidal transformer).  i seem to be getting a reading, on every single regulator, when i check to ensure there is no continuity between it (the regulator plate), and the chassis (for heat sinking).  the reading that i am getting changed when i turned the trim pot at the base of the respective regulator..  is there a chance that i am reading a path to ground through another path, and that i actually do not have a short on every single regulator to the heat sink?

Seems all fine. The JLM power station has 3 positive and 2 negative voltage regulators. The positive vregs LM317 have the regulated output voltage internally connected to their heatfin (and adjusting the output voltage by the respective trimmer obviously will change this voltage potential in respect to reference voltage), the negative vregs LM337 have the raw/unregulated DC voltage internally connected to their heatfin (and adjusting the output voltage by the respective trimmer should not change the voltage in front of the vreg). Your case is always connected to safety ground. You have connected your 0V reference voltage to this safety ground in one spot thru the 10R resistor, so your multimeter, set for reading DCV, would measure these voltages. (For usual you set your multimeter for reading ohms when checking for a short between vreg and case with the unit powered off).

 

[mikerl]

hey guys!

thanks, i worked this thing out.  its running and reading the correct voltages.  i was using the doubled up lamp chord, because i didn' t have and 3 conductor shielded, and figured it would do just fine, as opposed to me buying a bunch of cable, just for 3 feet of it....  i could change it, but am wondering if what i have will work just fine.  ill look around again and see if i have anything else.

 

[madriaanse]

Not sure if I should be posting this here or in the black market forum, but anyways, I have two EZ1290 PCB's that got scratched slightly in shipping. They're 100%, every bit as good as the other PCB's, but just have some scuffs and I don't want to sell them as new. Whoever emails me first gets them for free. My email is martin_adriaanse [at] yahoo [dot] com.

M.

EDIT: whoa, that was quick. They're gone.

 

[Chrome Heart]

Dangit. That was quick.

 

[dude24man]

no you have any more for sale?

 

[madriaanse]

two boards left.  Ordering more soon.

M.

 

[wimmy7986]

Hello all, newbie here.

I'm looking to finish one board with the AC/DC supply, but Digikey is currently out of the Trafo indicated.  Will this work as a replacement?

http://www.mouser.com/ProductDetail/Triad-Magnetics/VPT48-1040/?qs=sGAEpiMZZMvwUzoUXIIvyTw34uqMHR%252budyV6EVq1EYo%3d

It looks to be fairly similar to the specs of the one on the BOM.

Thanks!

 

[mikerl]

Hey!

so i have my 4 channels up and wired.  measning voltages.  lots of them are ok.  one of my channels (channel 2) is measuring nicely on the collector of TR3, but measuring low on the base and emitter (0.3 and 0. 8 ).  on that same channel, the TR1 measurments are All around 1.9-1.2 for each the CEB.  Any thoughts on this?  i will take the board out an look for shorts in that area.  when i plug a mic in, its really small sounding, and takes a LOT of gain to get useable signal.

the other thing, is that on two of my channels, i seem to have a position on the switch that does not get signal, and on one of those channels, once you go past that "no signal" position on the gain knob, it gets very noisy... this is with and without the pad.  There is NO PSU in the case.

any thoughts on either the voltages on my 2nd channel, or on the "missing" signal on certain gain settings?  i will have to pull the board and check for shorts on the switch resistors.


EDIT:  found a bad solder joint.  so the and im getting sound out of the second channel.  the problem now, is still that the voltages are off (in the same way they were above)

any thoughts are appreciated.

 

[possum2065]

A big thanks to everyone on this forum as I have just completed my 2 Channel 1073 and it sounds awesome.

 

[RedRabbit]

Big Thanks to Martin for shipping out my boards super quick earlier this summer!
I'm just about to get going on building these puppies, but just had a few questions to throw at the wall here before I ordered parts.
Thanks for any thoughts or comments.

1.C16- 1010pf polystyrene? I have 1000pf's ready to go in my parts drawers and the mouser part number goes to the 1000pf styrene. Is this just a formality of it being the closest available part?

2. Am I better off with axial or radial caps with this build? Is this just a formality? Seems some of the gaps are quite large and I'm looking at a great variety of how people have assembled it...I don't want to bodge this together. Any issues going one way or another?

3. Is there a carnhill toroidal for the PSU transformer that's available from audio maintenence? Or should I just go with the suggested TE62085-ND? i need to order a bunch of pots from them as well to refurb my Trident console and saving on shipping is a plus!

4. I'm planning on using 1% metal film resistors primarily because that's what on my workbench. Also the fact I have close to 75% of the values needed is a bonus as well. However, I have worked with an original pair of Neve 1073's with carbon comps for a few years and I'm lusting after that sound again. Is this really a moot point ultimately? My mind tells me that the metal oxide will sound clearer, but I don't know if that's a good thing in this case. Has anyone performed a critical listening test?


Thanks everyone!

 

[critterkllr]

I'm trying to source parts as close as possible to the original 1290. I've only found two pictures that appear to be the 1290 original circuit, but both have a .1uF/100nF capacitor (one has a mustard cap and the other a tropical fish). Can anybody tell me where this is located in the circuit? I don't see it in any schematic and there is no .1uF in the EZ1290. Thanks!

The other image is located at http://www.neve1290.com/nevepics.php

 

[critterkllr]

3. I'm planning on using 1% metal film resistors primarily because that's what on my workbench. Also the fact I have close to 75% of the values needed is a bonus as well. However, I have worked with an original pair of Neve 1073's with carbon comps for a few years and I'm lusting after that sound again. Is this really a moot point ultimately? My mind tells me that the metal oxide will sound clearer, but I don't know if that's a good thing in this case. Has anyone performed a critical listening test?

FWIW, I couldn't find any comparisons on this. I'm building 3 EZ1290s. One with carbon comps, one with metal films and another with NOS components found in the originals (except electrolytics). When I'm done I will check back to see if anybody is interested in comparisons.

 

[RedRabbit]

3. I'm planning on using 1% metal film resistors primarily because that's what on my workbench. Also the fact I have close to 75% of the values needed is a bonus as well. However, I have worked with an original pair of Neve 1073's with carbon comps for a few years and I'm lusting after that sound again. Is this really a moot point ultimately? My mind tells me that the metal oxide will sound clearer, but I don't know if that's a good thing in this case. Has anyone performed a critical listening test?

FWIW, I couldn't find any comparisons on this. I'm building 3 EZ1290s. One with carbon comps, one with metal films and another with NOS components found in the originals (except electrolytics). When I'm done I will check back to see if anybody is interested in comparisons.

I'm definitely interested in hearing your results when you're finished! Thanks for experimenting with this. Too bad you didn't finish them already so I would know what to do! 

 

[sr1200]

I did the 1% metal films on all 6 of my 1290 clones.  Love em!  The tranny's do a lot of the coloration... enough for me at least.

 

[critterkllr]

3. I'm planning on using 1% metal film resistors primarily because that's what on my workbench. Also the fact I have close to 75% of the values needed is a bonus as well. However, I have worked with an original pair of Neve 1073's with carbon comps for a few years and I'm lusting after that sound again. Is this really a moot point ultimately? My mind tells me that the metal oxide will sound clearer, but I don't know if that's a good thing in this case. Has anyone performed a critical listening test?

FWIW, I couldn't find any comparisons on this. I'm building 3 EZ1290s. One with carbon comps, one with metal films and another with NOS components found in the originals (except electrolytics). When I'm done I will check back to see if anybody is interested in comparisons.

I'm definitely interested in hearing your results when you're finished! Thanks for experimenting with this. Too bad you didn't finish them already so I would know what to do! 

I don't anticipate that it will make much of a difference outside of tolerance variation. Are you sure that your 1073 wasn't using Piher carbon film resisters? They look close to carbon comps.

 

[RedRabbit]

3. I'm planning on using 1% metal film resistors primarily because that's what on my workbench. Also the fact I have close to 75% of the values needed is a bonus as well. However, I have worked with an original pair of Neve 1073's with carbon comps for a few years and I'm lusting after that sound again. Is this really a moot point ultimately? My mind tells me that the metal oxide will sound clearer, but I don't know if that's a good thing in this case. Has anyone performed a critical listening test?

FWIW, I couldn't find any comparisons on this. I'm building 3 EZ1290s. One with carbon comps, one with metal films and another with NOS components found in the originals (except electrolytics). When I'm done I will check back to see if anybody is interested in comparisons.

I'm definitely interested in hearing your results when you're finished! Thanks for experimenting with this. Too bad you didn't finish them already so I would know what to do! 

I don't anticipate that it will make much of a difference outside of tolerance variation. Are you sure that your 1073 wasn't using Piher carbon film resisters? They look close to carbon comps.

It's very possible that it was using carbon film instead of carbon comp, but that's what I was told by the owner at my former place of employment. At this point, I'm probably just going to go metal film since it will save me a few bucks ultimately and those carnhills aren't cheap.

 

[critterkllr]

I have two noob questions about customing the EZ1290.

1) Is it possible to customize the impedance switch by having more than the two impedance options? For example, could I add a 300 ohm resistor in series with the 1200 ohm impedance wiring to make it 1500 ohm? The idea was to wire the standard switch, but to add a variable switch in series to allow for more impedance options.

2) Since Martin recommends leaving a trim pot out of the circuit due to noise, would the use of a variable trim switch allow for more options without drawbacks of using a pot?

One of the reasons I ask is because I have a stock of SP10T Grayhill switches I pulled out of some equipment that was getting thrown away. I'm wondering if I could use these to add more options to my preamps without affecting the general performance. I do like the sound of a slightly overdriven preamp at times and also use a wide variety high and low impedance mics.