Neve 1290 build completed!!

[leafcutter]

... i have no idea why i read spot on values  :

Me either because I have had the exact opposite experience, every time, trying to measure
resistors in circuit. You must have a magic DMM!

If you are reading resistors and they are strictly in series you can read accurately on the PCB as long as nothing is running in parallel. If your resistors are in parallel you need to lift them to read their values.

gerardmanvuca

I don't think the trim pot adds any gain at all, from my understanding it just allows you to select gain settings between the standard 5db steps. A fine tune pot if you will.

Having said that I have not actually built this yet so I might be wrong.

I have most of the components to build 4 1290 channels now including the lovely 2u racks that arrived this morning from http://modushop.biz/ (thanks for the suggestion snipsnip!!) - just waiting on pre-amp and power PCB's.....

Cant wait!

best,

John.

 

[kambo]

\
If you are reading resistors and they are strictly in series you can read accurately on the PCB as long as nothing is running in parallel. If your resistors are in parallel you need to lift them to read their values.

if i have a cap in parallel, it takes 1-6 sec to measure, depends on the cap value (filling time)

 

[stitch-o]

If you are reading resistors and they are strictly in series you can read accurately on the PCB as long as nothing is running in parallel. If your resistors are in parallel you need to lift them to read their values.

Interesting.
I will make a note to investigate this.

\
If you are reading resistors and they are strictly in series you can read accurately on the PCB as long as nothing is running in parallel. If your resistors are in parallel you need to lift them to read their values.

if i have a cap in parallel, it takes 1-6 sec to measure, depends on the cap value (filling time)

Please to read sig.

Cheers!

 

[Di_Sousa]

i have a question about the trim. if i instal the trim will it mean i can push the input gain more and therefore driving the circuit more to get a bit more warmth for colouring my mixes?

The trim pot will control to output gain.
So if you have a trim pot you could distort the input stage, and lower the output so you don't clip your AD converters.

makes sense?

 

[leafcutter]

Whoops,

I don't understand this - are we talking about the same trim pot (http://www.musiciansgig.com/ez1290/trimmer_v2.1.pdf)?

It looks from the schematic like this is an attenuator only, how can it boost the signal?

Maybe I'm missing something obvious.

Best,

John.

 

[gerardmanvuca]

Whoops,

I don't understand this - are we talking about the same trim pot (http://www.musiciansgig.com/ez1290/trimmer_v2.1.pdf)?

It looks from the schematic like this is an attenuator only, how can it boost the signal?

Maybe I'm missing something obvious.

Best,

John.

this is the trim i was talking about...so if its an attenuator i'm guessing it only attenuates the input gain?? i was hoping i could instal a trim on the output of the circuit so i could boost the input (therefor getting more drive/colour??) without clipping my AD...... is this possible or evan worth it?

 

[desol]

It'd be the same thing anyways. You just turn down the output, but keep the input high.

EDIT: The way it looks, is that the pot is in series with the output to 0v. Is that incorrect?

 

[snipsnip]

why dont you just turn down the source at source? This is what I do if I want saturation, although to be honest, I think this has plenty of shape and colour on the mix bus without driving it hard.

 

[Di_Sousa]

Whoops,

I don't understand this - are we talking about the same trim pot (http://www.musiciansgig.com/ez1290/trimmer_v2.1.pdf)?

It looks from the schematic like this is an attenuator only, how can it boost the signal?

Maybe I'm missing something obvious.

Best,

John.

maybe I wasn't clear enough before, sorry

the trim pot doesn't boost the signal, it attenuates the output

So you could distort the input stage (controlled by the 12 steps grayhill switch) , and lower the output (trim fader) so you don't clip your AD converters.

 

[leafcutter]

Got my Boards in the post yesterday and soldered up 4 channels minus a couple of caps that are on back oder.

Must say a big thanks to Martin for making it possible to build these pres. The boards are really really nice to work with, and the documentation plus the messages on the forum make it a breeze to build.

Looking forward to completing and hearing these 

 

[stitch-o]

I just had an interesting shootout with my EZ1290 pair.
I had one instance of crackle on the left channel. Quickly fixed the last solder point on the input transformer
that was funky and wired in the trimmers (pair of BI conductive plastic 5ks), did a quick test to make sure
everything worked well.
I had a call yesterday from a friend of mine who runs a bigger tracking studio near here.
He had a vintage BCM10 and currently has a rack of 8 x 1073 BAE reissues which he rents.
He asked me to bring my pres out as he didn't want to rent the rack anymore and was considering having me build 2 4xEZ1290
racks for him.
So the shootout was:
1 original 1073 handpicked from the BCM10 vs. 8 x BAE 1073 reissues vs. 2 x EZ1290s
Nothing scientific, just a 57 direct pumped through the mains doing vocal tests.
It was my friend, another engineer and myself, all the picks were unanimous.
The original, handpicked 1073 won.
EZ1290s got an easy second place (even with the trimmers in circuit)...
Needless to say I got the gig to build 2 four channel racks for the studio.

Cheers!!

 

[3nity]

Those guys dont know a thing 'bout great gear!!
I know few people freaking when they hear my 1290s with cinemags in it!!
Tell them to go see a doctor! ;D

 

[kambo]

which cinemags did u use ?
in : CMOQ-2 wired 2:1
out: CMOQ-2S wired 1:2

 

[mitsos]

Should be CMMI-2C on input. And I believe something like CMOQ1SG on output, but best to verify. Output has to be gapped in any case, so make sure you specify. CMOQ2 is a smaller trafo, should still work if it were made gapped, but not sure how sound would be affected.

 

[desol]

I just had an interesting shootout with my EZ1290 pair.
I had one instance of crackle on the left channel. Quickly fixed the last solder point on the input transformer
that was funky and wired in the trimmers (pair of BI conductive plastic 5ks), did a quick test to make sure
everything worked well.
I had a call yesterday from a friend of mine who runs a bigger tracking studio near here.
He had a vintage BCM10 and currently has a rack of 8 x 1073 BAE reissues which he rents.
He asked me to bring my pres out as he didn't want to rent the rack anymore and was considering having me build 2 4xEZ1290
racks for him.
So the shootout was:
1 original 1073 handpicked from the BCM10 vs. 8 x BAE 1073 reissues vs. 2 x EZ1290s
Nothing scientific, just a 57 direct pumped through the mains doing vocal tests.
It was my friend, another engineer and myself, all the picks were unanimous.
The original, handpicked 1073 won.
EZ1290s got an easy second place (even with the trimmers in circuit)...
Needless to say I got the gig to build 2 four channel racks for the studio.

Cheers!!

Cool. Now, if one had the original transformers...

 

[MatthewF]

Hi everyone,

I'm about to drill out a case to rack up two channels of this great project and I'd be grateful if those with experience could have a look over my planned layout, pictured below:

My concern is the close proximity of the PSU transformer to the right EZ1290 PCB. This PCB has ended up over there as a result of my attempts to get the audio transformers as far away as possible from the mains trafo. (The gap to the right of each EZ1290 PCB is necessary for phase/pad/phantom/impedance switches and output trims.)

I have no experience with polystyrene caps. Does anyone know if they, or anything else on that PCB, will be particularly susceptible to EMI?

Cheers for any help!

Matthew

 

[YLab]

I think its a good idea to put your psu and power transfo outside of your preamp just like in Martin's assembly guide..The idea is to avoid any hum that could contaminate those great preamp. And put the input and output tranfos as far as you can from each other. If you put them too close,, you risk to have some oscillation at hi gain setting.

Hubert

 

[desol]

I second that. Get another 1u for the power supply. Specially cause that case is only, what, 10" deep?
So, she's kinda tight. Plus, then you can move the outputs to the back, behind each card and the inputs on each side...or something.

 

[danjpiscina]

agreed. there's no reason to put the PSU in the same case. it's much simpler and better overall to put it in a box. it does make one extra thing to carry around, but it's not really a big deal.

this layout worked well for me:

http://www.groupdiy.com/index.php?topic=20152.msg419581#msg419581

all the best!

Dan P.

 

[Bluzzi]

Any hum I had on my 1290s was reduced immensely when I put the PS out of the case. Everything was fine after that. Its worth the extra effort.

Jim