madriaanse
Well-known member
Nice! I'm a sucker for vintage RCA knobs!
How do you like the sound?
M.
How do you like the sound?
M.
8 Channel, 3U NEVE 1073 completed
- Thread starter madriaanse
- Start date
Help Support GroupDIY Audio Forum:
Potato Cakes
Well-known member
Finally got it done. For the most part. I managed to break the solder legs for the trim pot on the fourth channel and somehow the ground connection on the third channel's JLM Go Between came undone. I had been pulling the PCBs out of the chassis repeatedly doing trouble shooting and eventually some of the connections broke. I was trying to get finished with it before I left town and I might have been a little more careless handling everything as my departure time drew nigh. But now I know exactly what I need to do to wrap it up and put it to good use as opposed to before when I was scratching my head and questioning all my life decisions.
My goal was to cram the power supply in the case and use some transformer shielding sheet from Don Audio to see how quite I could get the preamp closest to the PSU. The shielding material works really well, and the with the preamp at about 40 dB of gain it's still quiet enough for tracking drums and guitars, which is what I intended for this unit in the first place. I still could use some advice of anyone as far as the best way to attach the XLR grounds to the star ground. Should I just connect the inputs, outputs, or none at all. Everything seems really quite till about 60 dB of gain, then there is a faint buzz, which maybe just because the PSU is mounted inside. But at this setting with no pad just talking into a dynamic mic starts to overload my converters, and I try to keep record everything around -18 dBFS, so at those levels, it's pretty dang quiet, even the "noisy channel."
Also, I would welcome any other transformer isolation idea if someone would care to share. As it is, it will work great. This is a fantastic project and a pretty good confidence builder once everything works. Thanks to madriaanse for this project and to Dan at collective cases for making the chassis available. I can't wait to have some time at home when I do some tracking with these babies.
This is a pic of the inside layout.
My goal was to cram the power supply in the case and use some transformer shielding sheet from Don Audio to see how quite I could get the preamp closest to the PSU. The shielding material works really well, and the with the preamp at about 40 dB of gain it's still quiet enough for tracking drums and guitars, which is what I intended for this unit in the first place. I still could use some advice of anyone as far as the best way to attach the XLR grounds to the star ground. Should I just connect the inputs, outputs, or none at all. Everything seems really quite till about 60 dB of gain, then there is a faint buzz, which maybe just because the PSU is mounted inside. But at this setting with no pad just talking into a dynamic mic starts to overload my converters, and I try to keep record everything around -18 dBFS, so at those levels, it's pretty dang quiet, even the "noisy channel."
Also, I would welcome any other transformer isolation idea if someone would care to share. As it is, it will work great. This is a fantastic project and a pretty good confidence builder once everything works. Thanks to madriaanse for this project and to Dan at collective cases for making the chassis available. I can't wait to have some time at home when I do some tracking with these babies.
This is a pic of the inside layout.
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Potato Cakes
Well-known member
Potato Cakes
Well-known member
madriaanse
Well-known member
Nice work getting it sorted out! That's a really good looking build and a lot of horsepower in 1U! 
As for grounding, hook up input XLR's Pin 1 to 0V, and leave output XLR Pin 1 disconnected. The device after the preamp (comp, EQ, A/D, etc) should have it's own reference to ground. Therefore grounding pin 1 of the preamp's output XLR is not needed and will only increase the risk of ground loops.
On the input side you want to connect Pin 1 to 0V because the Mic/DI (likely) does not have its own ground reference and you definitely want that mic cable shielded. Note that 0V (ground) is different from earth (case) - there is a 10 Ohm resistance between them to avoid ground loops caused by devices with their own ground (such as tube condensers).
HTH,
M.
As for grounding, hook up input XLR's Pin 1 to 0V, and leave output XLR Pin 1 disconnected. The device after the preamp (comp, EQ, A/D, etc) should have it's own reference to ground. Therefore grounding pin 1 of the preamp's output XLR is not needed and will only increase the risk of ground loops.
On the input side you want to connect Pin 1 to 0V because the Mic/DI (likely) does not have its own ground reference and you definitely want that mic cable shielded. Note that 0V (ground) is different from earth (case) - there is a 10 Ohm resistance between them to avoid ground loops caused by devices with their own ground (such as tube condensers).
HTH,
M.
madriaanse
Well-known member
New V2.6 boards are ready! These boards have footprints for radial polypropylene caps and optional terminal blocks. ;D
Revised BOM and assembly guide below:
https://s3.amazonaws.com/EZ1290/1290BOM26.xls
https://s3.amazonaws.com/EZ1290/assembly6.pdf
M.
Revised BOM and assembly guide below:
https://s3.amazonaws.com/EZ1290/1290BOM26.xls
https://s3.amazonaws.com/EZ1290/assembly6.pdf
M.
Potato Cakes
Well-known member
Martin,
Thanks for the info! I'll go through and redo the grounding I have now to see if can get better noise results. I also had placed the input transformers underneath the PCB since I had a decent amount of space underneath.
It's actually a 2U case from Dan at Collective Cases. I wish I could fit it all in a 1U!
Thanks again for a great project! I'll report back when I get back home from the road and make these changes.
Thanks!
Paul
Thanks for the info! I'll go through and redo the grounding I have now to see if can get better noise results. I also had placed the input transformers underneath the PCB since I had a decent amount of space underneath.
It's actually a 2U case from Dan at Collective Cases. I wish I could fit it all in a 1U!
Thanks again for a great project! I'll report back when I get back home from the road and make these changes.
Thanks!
Paul
Hi everyone!
I'm just wondering if this build is suitable for 2 buss coloring? I don't really record any mics I just want to color my ITB mixes and run some analog synths through it! Would I need a DI handle the synth?
I'm clueless about what levels to send it? 75dB of gain on tap sounds like an awful lot! Do I need a DI to connect it from my DAW?
How does one get the most color out of the unit? Hit it hot and use the minimum amount of gain or hit it cold and boost a lot?
I was thinking about building a 2-ACA-BO box but I've heard Neve stuff and they do sound really sweet as well!
Oh I'm a newbie at electronics and levels!
I'm just wondering if this build is suitable for 2 buss coloring? I don't really record any mics I just want to color my ITB mixes and run some analog synths through it! Would I need a DI handle the synth?
I'm clueless about what levels to send it? 75dB of gain on tap sounds like an awful lot!
Do I need a DI to connect it from my DAW?How does one get the most color out of the unit? Hit it hot and use the minimum amount of gain or hit it cold and boost a lot?
I was thinking about building a 2-ACA-BO box but I've heard Neve stuff and they do sound really sweet as well!
Oh I'm a newbie at electronics and levels!
madriaanse
Well-known member
Hi Xaxau,
Maybe something like this (in addition to the preamps) would suit your purpose? http://www.diyrecordingequipment.com/collections/frontpage/products/l2p?variant=1222659284
I have used the EZ1290 for makeup gain after a passive summing box and it performed admirably. The preamp did a good job sweetening the edgy digital top end. The low end sounded a little bigger/fuller as well. Headroom for days too.
M.
Maybe something like this (in addition to the preamps) would suit your purpose? http://www.diyrecordingequipment.com/collections/frontpage/products/l2p?variant=1222659284
I have used the EZ1290 for makeup gain after a passive summing box and it performed admirably. The preamp did a good job sweetening the edgy digital top end. The low end sounded a little bigger/fuller as well. Headroom for days too.
M.
Yeah that little box will do the trick! What about the JLM DI? Will order the Go Between from him anyway!madriaanse said:
What is the level of difficulty for this build? I'm a virgin but have been reading up on diy for a while now!
I have a JLM Kraftwerk PSU that I was going to use to build a CAPI 2-ACA-BO with lots of DOA's. Will it work for this project? I think I got a 30VA mains trafo.
The optional trim pot, is it post the output transformer?
Is there a difference in operation or sound with the 1200/300 impedance mod when using it for line purposes?
madriaanse
Well-known member
Hi XAXAU,
I think the JLM DI is HI-Z only - not Line input.
It's a pretty easy build if you carefully follow the the assembly guide. Maybe read it a few times beforehand. People with no prior electronics experience have been able to successfully build the EZ1290.
If the PSU can give you ~1amp @ 24V you should be golden.
Optional trimpot is between pre-stage and output stage; so before output transformer.
There can be a pretty big difference in sound (and level) between 1200/300Ohms. Most people use the 1073 at 1200 Ohms, but you can certainly experiment to suit your taste. You just need a DPDT switch to make it switchable.
DIYrecordingequipment.com has kindly offered to sell the PCB's and they are now available here as well: http://www.diyrecordingequipment.com/products/ez1290-preamp-pcb?variant=3688377412
Best,
M.
I think the JLM DI is HI-Z only - not Line input.
It's a pretty easy build if you carefully follow the the assembly guide. Maybe read it a few times beforehand. People with no prior electronics experience have been able to successfully build the EZ1290.
If the PSU can give you ~1amp @ 24V you should be golden.
Optional trimpot is between pre-stage and output stage; so before output transformer.
There can be a pretty big difference in sound (and level) between 1200/300Ohms. Most people use the 1073 at 1200 Ohms, but you can certainly experiment to suit your taste. You just need a DPDT switch to make it switchable.
DIYrecordingequipment.com has kindly offered to sell the PCB's and they are now available here as well: http://www.diyrecordingequipment.com/products/ez1290-preamp-pcb?variant=3688377412
Best,
M.
Rocinante
Well-known member
I realized I hadnt posted any pics of this awesome project.
Thanks Martin I use it all the time.
Thanks Martin I use it all the time.
So if I pad it down -30dB with the box you recommended I should be able to jack in line grow DAW plus an analog synth? Don't know the impedance of the synth though.
The PSU can do 3x pos and 2x neg @1,5A so it should be enough!
The PSU can do 3x pos and 2x neg @1,5A so it should be enough!
madriaanse
Well-known member
Rocinante said:I realized I hadnt posted any pics of this awesome project.
Thanks Martin I use it all the time.
Wow! That looks stellar! Very, very nice build!
M.
madriaanse
Well-known member
XAXAU said:
Hey, I'm not clear on what you mean by the above sentence. Can you explain?
Sorry,
M.
madriaanse
Well-known member
Yes, you can but not at the same time.
madriaanse
Well-known member
Yes, I did think about adding the line-in section, but it doesn't really make sense to add it unless you are also incorporating the EQ section. Very few people need line gain, but (almost) everyone needs a mic preamp. Hi-Z input can be added to the EZ1290 using a JLM Go Between.
I did make a 1073 line board (with proper 31267 input transformer) a few years ago but discontinued it because there was very little interest in it. Please see: http://groupdiy.com/index.php?topic=34292.0
Best,
M.
I did make a 1073 line board (with proper 31267 input transformer) a few years ago but discontinued it because there was very little interest in it. Please see: http://groupdiy.com/index.php?topic=34292.0
Best,
M.
