8 Channel, 3U NEVE 1073 completed

[RedRabbit]

Awesome!  Thanks for pointing out the hammond options.  I think I've narrowed it down to this model... http://www.mouser.com/ProductDetail/Hammond/182L12/?qs=%2fha2pyFaduhkZsoALO1xLH8m%2fA88eyezwSWKx62QmIo%3d

There's also a 30 VA option

Can anyone confirm this will work for one or two channels?  I'm a noob when it comes to power transformers, and just want to be extra sure...  Thanks

For one or two channels, Digi-Key has this in stock: http://www.digikey.com/product-detail/en/62075-P2S02/TE62075-ND/299875

Not sure if it will work, but it seems like it should.

I just finished building my power supply with this toroid and a JLM AC/DC and it works perfectly fine.

 

[desol]

It seems like a lot of guys don't have access to an oscope and signal generator. Did anybody do a before and after to test the difference between biasing correctly and the ballpark voltage listed? I hooked mine up before because I let somebody borrow my oscope. It sounded good before, but after biasing seemed to sound wider with more of the signature pronounced chunky low mids. Sound went from very Neve inspired to Neve.

Just wondering if others could share their experience so people without a scope could potentially make some adjustments using their ears.

Page 84 of the thread had a discussion on that topic recently.

Checked the thread a few times for the audio difference between biased and under/over biased and can't find anything.

One more question. What are the different specs on using a 5k or 10k pot for trim? -20db, +/-10db, etc? Is it passive with unity turned fully clockwise, or active like some Neves where unity is at the center?

It's an attenuator. It's full on clockwise...back it off to trim it down...

 

[critterkllr]

Has anybody A/B'd the difference between using BC184C and MPSA18 transistors? I know that the MPSA18s work as I'm using them in a pair. However, the pair that I have runs pretty loud. Since the MPSA18s tend to be around 800 to 900 hfe and the BC107Cs around 400 to 600, I'm wondering what this difference does to the sound.

 

[desol]

I'm by no means a trained tech or engineer, but I believe the MPS simply has a higher Forward Current Gain (hfe) capability....

So, it really shouldn't matter so long as the base, collector, emitter footprint is the same...

 

[critterkllr]

I'm by no means a trained tech or engineer, but I believe the MPS simply has a higher Forward Current Gain (hfe) capability....

So, it really shouldn't matter so long as the base, collector, emitter footprint is the same...

Thanks Desol!

 

[lampas]

Just wonder about trim pod. It is connected  before last stage (2N3055). But if you want to saturate output transformer, wouldn't it be better to put in the end, just before output XLR, after 1,5K resistor and 0,01u capacitor ?

 

[critterkllr]

Has anybody tried the input and output trannies from Neve? Check the Neve Classic spares section:

http://www.ams-neve.com/support/neve-spares

 

[sr1200]

They look like carnhills... just more expensive!

 

[critterkllr]

They look like carnhills... just more expensive!

Sure, but doesn't Neve claim that their transformers aren't the same and go through more thorough testing? It seems like there is a bunch of speculation, but now their claims can be tested. I may bight the bullet and pick up a set to A/B against another pre with the standard Carnhills, but would like to hear if anybody else has done the same first.

 

[sr1200]

What i think is even better is the 33609 front panel and all the switches caps and meters...

 

[desol]

They look like carnhills... just more expensive!

Sure, but doesn't Neve claim that their transformers aren't the same and go through more thorough testing? It seems like there is a bunch of speculation, but now their claims can be tested. I may bight the bullet and pick up a set to A/B against another pre with the standard Carnhills, but would like to hear if anybody else has done the same first.

In all honesty...I doubt the Neve spec is the same as the standard Carnhill issue...but, I could be wrong!
I'm sure the standard Carnhill is fine tho...

 

[madriaanse]

I have some more boards in stock. For those who were waiting on boards, please email me if I haven't emailed you already: martin_adriaanse (at) yahoo (dot) com

Cheers,

Martin

 

[seavote]

powered up my 2 channel 1290 build. no signal out of one side.(have not trouble shot that side)  other side distorted signal.
transistors readings were good except tr1  b and e  both read.4mv,base not greater than emitter.  and tr2 c reads 2.48V instead of 22V area. I found one 82UF25V electrolytic in backwards(don't know a component # but its the one closest to tr1) cap tested good I reinstalled correctly but the problematic voltages remained the same. are there any specific components that could be suspect because they could have been damaged because of the cap being reversed? or obvious spots to check that I dont know enough to deduce. any suggestions are appreciated, 8) 8) 8) 8) 8) 8) 8)

 

[desol]

"are there any specific components that could be suspect because they could have been damaged because of the cap being reversed?"

yep.

Trace it with a scope.

 

[seavote]

No scope but I'll trace the best I can with some alligator clips and a powered speaker. I can't find the 1 watt 10 ohm (r98 on the ba183 schematic) going to earth ground on the PCb . What is the proper way to ground a 2 channel EZ 1290? Thx

 

[sr1200]

Why not use the schematic for this unit?  Its in the back of the build guide.
http://s3.amazonaws.com/EZ1290/assembly3.pdf

 

[seavote]

That's the schematic I'm looking at. I guess my real question is , do I install r93 off board or am I just not seeing it. It's difficult to determine component #s  from a populated board because component values are covered by components. There is no 1 watt 10 ohm resister off of the 0V pad on the PCB. Just thought Madraanse may have placed it elsewhere on the board.

 

[sr1200]

If im not mistaken, that part is un-needed as the JLM power supply already provides the 10ohm to chassis.  But I see what you're saying.

 

[desol]

That's the schematic I'm looking at. I guess my real question is , do I install r93 off board or am I just not seeing it. It's difficult to determine component #s  from a populated board because component values are covered by components. There is no 1 watt 10 ohm resister off of the 0V pad on the PCB. Just thought Madraisse may have placed it elsewhere on the board.

Yes, it's been covered a few times. All the Jlm supplies (i think) come with the 10 ohm resistor. You should have 10 ohms between chassis and 0 volts on the supply.

 

[remsouille]

Hey there fellas!
I'm about to complete my 6 channel unit, and I must say I'm quite pleased about the way it came together:

Can't wait to silkscreen it!!!
I used a screened power transformer to be able to put it in the case, and I have on ACDC for every two channels. All channels are functional, however I seem to have a little problem...
My 48v rail works fine, but when I tried to hook up two of the leds to one of the acdc's, the damn 47ohm resistor on the acdc blew  . When I disconnect the wire that goes to the led - to 0v, everything's fine.
Resistance between 0v and chassis reads 3,7ohm on every acdc .
Anyone have an idea where I should look into?
Thanks!!