3D "AIR" EQ - "Night EQ" PCB's Complete!

[wave]

Hi Thank You Rellister! 

I used the BOM values for all of the resistors.  I just followed everything as close as I could, including all of the inductors, etc...

All pots neutralized sounds almost perfectly flat, I'd like to scope it to check there might be a slight bass decrease, I can't tell.  All the pots from audio maintenence measured around 50k and 60k at center point so I decided not to mess with swapping resistors values. 




Greg

Greg,
Do you have a Mouser cart for this project you can share?

Wave

 

[bieckmusic]

Hi Wave,

Sure no problem.  I need to edit a few things on there and consolidate two mouser orders into 1, then I can pass it on to you.
best,
greg

 

[wave]

Hi Wave,

Sure no problem.  I need to edit a few things on there and consolidate two mouser orders into 1, then I can pass it on to you.
best,
greg

You totally rock!!

EDIT: My 100th post!!

 

[bieckmusic]

Here's what I used for my EQ3d project.  I preface this by saying, it's not guaranteed or a professional BOM in any way.  It's just what I used for my eq 

Also, a few of the power supply electrolytic caps I used are too tall for a 1 rack space eq. 

The parts listed here are for the SSL 9k power supply which is what I used to power the project.  I built my unit as a self-etch and didn't have access to the standard EQ3d power supply board.  If you are not using the SSL 9k power supply you will have to ignore this BOM.
There are two sets of inductors on the BOM, I'm not sure which ones I used, probably the cheaper ones  ;D

BOM for 1 channel EQ (1 board, for stereo order 2)
http://www.mouser.com:80/ProjectManager/ProjectDetail.aspx?AccessID=332e141d2d

op amps for 2 boards
http://www.mouser.com:80/ProjectManager/ProjectDetail.aspx?AccessID=01f16ca11a

SSL power supply
http://www.mouser.com:80/ProjectManager/ProjectDetail.aspx?AccessID=370e48c7ce

 

[earthsled]

make R201 a rheostat to dial in less sensivity. Voltage gain of this inverting stage is R201/R200.

Ah! I think I found the issue with my clipping indicators... The schematic shows R200 with a value of 4K46. From the attached pic, it looks like the value should have been 46K4 instead.

 

[bieckmusic]

Hi earthsled,

How did you go about making your clipping indicator.  Did you breadboard it just by referencing the schematic??  Or did you design a circuit board and etch it?  I'm thinking of trying to build one by referencing the schematic just to develop some skills...    Thanks, hope you don't mind my asking...

have a great day!

best,
greg

 

[earthsled]

I made my own PCB for the EQ and included the clipping circuit. For this, I referenced the schematic, original layout, etc. I didn't etch -- I ordered the boards from Advanced Circuits (check out their "BareBones" and "$33 each" deals). http://www.4pcb.com/index.php?load=content&page_id=129

If you're on a Mac - I'd also recommend OsmondCocoa for PCB design software. http://www.osmondpcb.com/

You could totally build the circuit on a breadboard though. Like you said, it's good practice!

Cheers!

 

[bieckmusic]

Awesome, thanks for the tip! 

 

[e.oelberg]

I just finished my nite eq, with some little changes different opamps and different balancing amp.
Noisefloor -101dB RMS eq switched on

Nicholas

 

[e.oelberg]

btw I used 50 k rev log pots... easier to find and less resistor noise than 500k you have to change all 5K62 resistors to 562  also the 56K2 resistor have to be replaced with 5k62. sound is exactly the same, just maybe less noise.

 

[e.oelberg]

btw I used 50 k rev log pots... easier to find and less resistor noise than 500k you have to change all 5K62 resistors to 562  also the 56K2 resistor have to be replaced with 5k62. sound is exactly the same, just maybe less noise.

I just measured it. Now I have -106 dB rms ... so it makes a difference

 

[Whoops]

No Center Detent-Ident on the pots makes this project much less interesting.

The Pots with the right value and center detent are easily available from audiomaintenence , theres no reason to use any other value.

btw I used 50 k rev log pots... easier to find and less resistor noise than 500k you have to change all 5K62 resistors to 562  also the 56K2 resistor have to be replaced with 5k62. sound is exactly the same, just maybe less noise.

 

[e.oelberg]

level matching is not that easy with that project and the curve it did with the center ident pots looked like a snake,
I prefer having no ident, and check visually for center. And the benefit of 50k vs 500k resistor noise is also worth
to consider. I had one board with 50k pots and one with 500k pots and I didn't hear a difference, just the noise floor is lower.
I might work on a pcb with lorlin switches for a stepped version.

I have a set of 12 audiomaintanace 500k rev log pots center ident for sale !

 

[Whoops]

level matching is not that easy with that project and the curve it did with the center ident pots looked like a snake,
I prefer having no ident, and check visually for center. And the benefit of 50k vs 500k resistor noise is also worth
to consider. I had one board with 50k pots and one with 500k pots and I didn't hear a difference, just the noise floor is lower.
I might work on a pcb with lorlin switches for a stepped version.

I have a set of 12 audiomaintanace 500k rev log pots center ident for sale !

yes Level matching is quite easy, just use the excel file attached, and actually the level matching will always be a problem even if you use center ident or not.

Have a center ident pots and using the excel file to calculate the resistors to attain level matching is just a matter of making it as best as possible instead of making a poor build.

I would like to buy the pots from you,
send me a pm

Thanks

(delete ".doc" from the extension, this is a RAR file)

 

[whomper]

Hi,

Is there a front panel file that could be shared? Am working now to design my front panel and would be happy to use an already made one.

Thanks,

Whomper

 

[Rellister]

I think Purusha still has cases, If that´s an option for you.

Cheers

 

[Rellister]

Hi,
Can anyone help me understand something strange;
I tied my XLR pin 1´s to star ground. When I hook up the boards to the PSU, the neg. rail drops down to about -1,5V and the toroid makes a buzzing noise. It seems like the neg. rail get shorted somehow and the toroid can´t handle it. When I remove the grounding from the xlr´s everything goes back to normal, all voltages measure as they should.
Haven´t tried passing sound through it yet.
This might be something trivial, I´m not experienced enough to figure it out, but maybe someone who understands the circuit better than me can explain it?
All help appreciated!

Thanks
Rune

 

[whomper]

I think Purusha still has cases, If that´s an option for you.

Cheers

Thanks, he does seem to offer a case plus front panel, but due to weight,vthismwillvcost me a fortune with shipping.

 

[Rellister]

Hi,
Can anyone help me understand something strange;
I tied my XLR pin 1´s to star ground. When I hook up the boards to the PSU, the neg. rail drops down to about -1,5V and the toroid makes a buzzing noise. It seems like the neg. rail get shorted somehow and the toroid can´t handle it. When I remove the grounding from the xlr´s everything goes back to normal, all voltages measure as they should.
Haven´t tried passing sound through it yet.
This might be something trivial, I´m not experienced enough to figure it out, but maybe someone who understands the circuit better than me can explain it?
All help appreciated!

Thanks
Rune

bump...

Checked all my opamps, they seem fine, measure +/- 6Mohm between pins 4&8.
Res. between +/- rails & opamp pins also fine, 22ohm.
Resistance between +/- rails seems a bit low, about 1,5-2K? Beats me.
Using a mnats PSU with regulators mounted to chassis, but with mica insulators. Could the issue be here anyway?
I get continuity from regs to chassis ground, is that the issue? Still, voltages are fine at psu output.

Voltages at opamp pins are correct. +/- 18V here.
The issue is, there seem to be some voltage potential at PSU ground, and if i tie it to chassis(star) ground there is a short.
I´m a afraid to damage someting else if I hook it up, so I´d like to get to the bottom of this first!

Cheers

 

[peterc]

The issue is, there seem to be some voltage potential at PSU ground, and if i tie it to chassis(star) ground there is a short.

Could just be spurious AC. Try using a 10R resistor to tie the PSU ground to chassis, if there is a problem, that will burn out or the fuse will
blow first.

Peter