8 Channel, 3U NEVE 1073 completed

[leitrim_lad]

so i checked my grounds and everything seems to be ok.. channel 2 is working fine. channel 1 however is still getting these weird pops, and when i touch the front panel i can hear is clearly. also when i touch things like the tops of the capacitors i can hear them clearly as well in the headphones or even just rub the card itself can be heard. do u still think its a ground issue? and if so what might i be doing wrong or whats the best way to ground this?

 

[Dr_J]

Hi leitrim_lad,

i would bet that you still have a ground or wiring issue.
Just follow straight the documentation of martin and you should be fine.
Good luck!

 

[leitrim_lad]

I cant seem to find anything wrong with the grounds.. channel 2 seems to be working perfect but channel 1 isnt. i didnt build this you see. i bought it second hand so im trying to figure out whats wrong. i cant figure out how the psu case is wired to the 1290 case or is this needed? der seems to be 2 wires going from the shield on both channels to the outside pin coming out of the output xlr on channel 2. is this correct? Iv included pics.. if you can see anything it would be greatly appreciated. thanks a million

 

[leitrim_lad]

pic2

 

[leitrim_lad]

pic3

 

[leitrim_lad]

Something else i noticed.. There seems to have been 3 50v 82uf caps used instead of 3 25v 82uf on the board where the problem is.. Would this make a difference? Ive included a pic..

 

[leitrim_lad]

Also the cap beside the switch on the good channel is in the 2 holes closest to the switch, on the faulty card its on the 2 outside holes.. would that make a difference?

Cheers..

 

[MicDaddy]

Is the shield hooked up to the PCB relating to the wire coming from PCB audio out to output transformer? 

It looks like they are trying to tie the PCB mounting screw to a wire my guess is to the chassis?  Get rid of this...

The wire dress in general leaves much to be desired.

The capacitor footprint I believe should be ok, I think it's meant to be versatile for varying lead spacing.

I don't know what is happening within the PSU enclosure with that big honking resistor.  Yellow electric tape is generally not a good sign.

Caps rated at a higher voltage 'shouldn't' be a problem (someone correct me here if needed).

 

[desol]

I'd almost be inclined to suggest (...for your own peace of mind, and learning) to remove and redo the wiring, both in the preamp case and the power supply. It looks like he didn't really know what was going on...then just decided to sell the unit.

You have some good components to work with and the pre's can sound good. Redoing the wiring will give you a chance to remove everything, have a look at what's going on...and then redo it all to your own standards.

 

[delir66]

Hey guys! After 20 pages of posts I'm back again. I've been working abroad and this project has been boxed for a while....
Recycled a 2u rack chassis from an old amplifier and started the build, not being really tide cause that's not gonna be the final casing.

I'm at the final stage where biasing the driver stage.
Voltages are ok referred to Martin's chart, but since I borrowed a sine generator and I own a digital osciloscope, I'd like to do it the recommended way. Not really an expert with oscil.loscopes, and since I don't seem to be able to reproduce the same situation Martin describes on the biasing, I've got some questions:

-What should be the input amplitude for the 1k sine? If my pres are half the gain and the generator is also half the gain, I get a normal sine wave. As soon I increase the gain on the pres (via switch), the signal goes off the scale and I can hear my output trannies singing loud.

By having the pres half gain and increasing the volume on the generator, I start getting the distortion, but pretty much the same on both sides. The plain clips on the signal, seem to be longer on the negative clips than on the positive ones. By turning the 5k log cannot appreciate much difference since it flucutates a bit.
Dont' know If I'm doing something wrong. But found the process not to be accurate at all, 5 turns on the 5k log don't make any difference on the scope or the voltages on the transistors.

Maybe I'm doing something wrong...
Should I use the attenuator on the probe?

Haven't been able to hear the pres since I've got nothing to feed at today. Tomorrow will go for a try.

 

[delir66]

Well, I'm still on the test biasing process, I mean, stuck on it.
Not really sure about the changes when turning the 5k log, but I have tried an sm-58 and a cheap akg condenser mic... AWESOME!!!
At full gain can hear the crackling of my saliva really loud!  they are quite as... don't know... quite!!!!

I'll keep on testing them out, but for the moment I must say....

THANKS MARTIN!!!!!  ;D ;D best audio diy ever!!!!

Reading about the 2N transistors on this post, I saw the recommended brand is Motorola. I'm not concerned about that at the moment, but the ones I got are StMicro, and the hfe I get on my semiconductor tester is 50. Isn't that too far away from the recommended 600 gain?

Thanks again for this project!

 

[Mr.GrinchSD]

ok So my 0v on the 1290 board to ground is reading .08 not 0 but when I test it at the JLM it reads 0 I tried messing around with the trim but nothing happens????

 

[desol]

Your 0v to ground should be 10 ohms.

 

[Mr.GrinchSD]

O ya HAH

 

[analogstud]

Hey Guys! Quick question. This seems to be fairly subjective, and scanning this thread but can't seem to find much detail on a certain (best) replacement for the obsolete BC184C's in the EZ1290. There are a few suggestions but what is the one everyone has settled on? Otherwise, I was just thinking this one: http://www.mouser.com/ProductDetail/Fairchild-Semiconductor/BC550CBU/?qs=sGAEpiMZZMsTKkj12KWLXhbg%252bxayotvaAhLFvgBk94w%3d

Thanks Guys!

Dave.

 

[desol]

Not sure. This isn't too too bad of a deal: http://www.ebay.com/itm/BC184-BC184C-NPN-TRANSISTOR-FOR-SINCLAIR-PACK-OF-20-/320724381644?pt=UK_BOI_Electrical_Components_Supplies_ET&hash=item4aaca9afcc

 

[3nity]

Eddie Ciletti has been using MPSA-18 for quite a while now.
I ve been using those too on EZ1084, 1272s and 1290...
Just turn them 90 degrees and you'Re good.

 

[analogstud]

@desol

I suppose that's better than $1-2.00 I've seen others trying to get per unit! I'll keep that in mind.

@3nity

Know of a supplier here in the States? Can't seem to find much info on those :-\

Thanks Guys!

 

[3nity]

Analog.
Typo my bad right part is MPSA-18.
Should be available although is going obsolete.

If you really need BC184C contact our fellow member called Bluzzi....the guy for the EZ1084...i think he got some!
Thanks

 

[mr.fofith]

Can someone give me a brief rundown on how to wire up a JLM Trex to this?