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

[khstudio]

[quote author="clintrubber"]Cool, enjoy ! :thumb:



[quote author="khstudio"]
I'm an eager student

Kevin[/quote]
Even more :thumb:


BTW, I like the drawing style of your schematics better than what I use (Simetrix). So I'm curious, which program are you using ?

And can you run a circuit simulation from it (either directly or after some exporting of the netlist).

Thanks,

Peter[/quote]

No Simm... but it's free. PCB & Schematic software www.expresspcb.com.

Can you comment on wether my redesign of that stage I posted will work or not???
Also, I'm not sure of a couple thing that Harpo said although I think he know a thing or 2 :green:

Kevin

 

[clintrubber]

[quote author="khstudio"]No Simm... but it's free. PCB & Schematic software www.expresspcb.com.
[/quote]
Thanks for the link. Hmm, bummer we can't go to a simulator directly from there. Simetrix-circuit-drawing are fine but could be better. Does sim of course, but no PCB. I'll try the sch-side of ExpressPCB

Must have a further read of all the new stuff above before I can comment.

Bye,

Peter

 

[Harpo]

[quote author="khstudio"]
#2
I do not think U1 is an inverting stage :? 5 I think is... how would raising that value affect the other summer from the AIR BAND (5.6k)???[/quote]

This is what I tried to show. R35 or better said R34 in series with R35 is the input resistor of the summer U5. (Pin2 of U5 is the summing node) This Rin has a value of 5.6k for max boost up to 506.6k for lowest amplification. (AV=-Rf/Rin = -56.2k/505.6k up to -56.2k/5.6k). U1 for shure is non inverting. You only have 1 summer (U5) and both paths from airband and fullband add up. If you don't want to go the well thought way clintrubber described, this may be a compromise.

Going thru the stages you get AV=0.5 at U4(input), AV=0.1 at the voltage divider R25/R24, AV=10 at U1, AV=-1 at U5 and AV=-2 at U4(output), so your total voltage gain is 1 for your fullband. The airband adds up its +-20dB, so overall gain is always more than 1 above airband.

Just another idea:
Changing your fullband to lowpass with a cap across R11 will catch this. The cap value would be switched with another deck of SW1 and set to the same -3dB frequency as your airband. (C-lowpass=1/(2*pi*R11*freq)).
Setting R11 to 10k the values for C across R11 will be
switch-pos. 2.5khz airband -> C=8nF
switch-pos. 5khz airband -> C=4nF
switch-pos. 10khz airband -> C=2nF
switch-pos. 20khz airband -> C=940pF
switch-pos. 40khz airband -> C=440pF
switch-pos. OFF airband -> C=leave out
If you want R11 100k (your pot), divide previous cap values by 10

[quote author="khstudio"]
#3
C13 does NOT connect to pins 1 & 8 on the PCB... not sure what you mean there???[/quote]

Some brands of NE5534 tend to hf-oscillating when not compensated. A 22pf cap between pin 5 and 8 prevents this. Sorry for typo pin 1.
http://focus.ti.com/lit/ds/symlink/ne5534a.pdf

[quote author="khstudio"]
Will my NEW setup that I drew (posted above) work? I already hooked it up but I can change it if need be. With the 100k pot maxed & 10k resistor to GND should give me 10x right?[/quote]
It will work, but may generate more offset and noise, but we're already at line level. If you add the lowpass cap, these get f**ing small at 100k.

close to 3am - time for bed
all the best
Harpo

 

[khstudio]

IT WORKS :razz:

x

 

[BR]

Hi Kevin,

Bourns pots actually describe their Rev Log as CCW log. If you want what you described, you need to order a CW log and wire it reversed.

peace
Gil

 

[khstudio]

x

 

[khstudio]

That damn 150 ohm 10 watt (I found one) is cooking too

What the hell... something with that thing doesn't seem right.

Do you guys think it's needed. I rechecked the original & it's there... but that was with a switching power supply... don't know but it's way too hot.

I will try to make some samples but it won't be for a few days.


Kevin

 

[Purusha]

Hey Kevin. Great work! I see it's going nicely towards the new DIY project :thumb:
I am also glad we can use Mnats PSU boards as I have a bunch of them at home :wink:

Can't wait to see the final layouts and all. Keep up the good work.

 

[MrZpliff]

Great Job ! :thumb:

Are the schemo correct ?

would be nice to have the option to build the full EQ or just the "air"
on the same pcb I think.... would be possible I guess...

 

[Harpo]

[quote author="khstudio"]That damn 150 ohm 10 watt (I found one) is cooking too

What the hell... something with that thing doesn't seem right.

Do you guys think it's needed. I rechecked the original & it's there... but that was with a switching power supply... don't know but it's way too hot.

I will try to make some samples but it won't be for a few days.


Kevin[/quote]
leave it out or replace it with a smoothing cap. It's not needed for linear supplies in this case. This R pulls 0.12 A as a min load for the switching supply.
Nice to hear it is working as desired.
:thumb:
You won't need the inductors on output for testing.

 

[khstudio]

x

 

[khstudio]

500k reverse Audio Taper Pots

Please help if you have a source with a decent price :!:

These can get expensive

Kevin

 

[Purusha]

OK, who wants some 3D EQ cases :green:

No seriously, I would really like to DIY a few channels of this great EQ and put them in a nice racks :razz:

Hey Kevin, so it's all ready to rock'n roll? If the full PCB layout is ready I would like to have it for sure.

Please send it to my email and thanks for doing this. :thumb:

 

[bellyflop]

[quote author="khstudio"]500k reverse Audio Taper Pots
Please help if you have a source with a decent price :!:
[/quote]What are you looking to spend? Small Bear has them.

 

[khstudio]

[quote author="bellyflop"][quote author="khstudio"]500k reverse Audio Taper Pots
Please help if you have a source with a decent price :!:
[/quote]What are you looking to spend? Small Bear has them.[/quote]

EXCELLENT :thumb:

 

[khstudio]

[quote author="Purusha"]OK, who wants some 3D EQ cases :green:

No seriously, I would really like to DIY a few channels of this great EQ and put them in a nice racks :razz:

Hey Kevin, so it's all ready to rock'n roll? If the full PCB layout is ready I would like to have it for sure.

Please send it to my email and thanks for doing this. :thumb:[/quote]

I need to adjust the PCB just a little then I'll send it out :wink:

Hang in there.

Kevin

 

[Purusha]

[quote author="bellyflop"][quote author="khstudio"]500k reverse Audio Taper Pots
Please help if you have a source with a decent price :!:
[/quote]What are you looking to spend? Small Bear has them.[/quote]


Hey, is this the same thing?

http://www.banzaieffects.com/Alpha-16mm-FS-500k-REV-log-pr-17321.html

 

[khstudio]

More Testing:

SM58, NEVE 1272 to balanced line in on board (Topaz Project 8)
Using the insert point to insert EQ (unbal) for testing & pulling for true BP listening -

For the hell of it I decided to do a comparison against my boards EQ (which I never thought was too bad... usable actually in moderation) & I was shocked how crappy it sounded compared to my high shelf only version of this EQ :shock:

No JOKE! WAY more transparent & just sweet... all the bands from 2.5k to 40k. I REALLY like the 2.5k, 5k & 10k on vocals so far. This was very rewarding for all the hard work.

I'm trying to regroup here & get all the files in order so hang in there.

I think some better quality caps in the signal path & larger PS filtering may improove it even more.

STILL NEED advise on the BEST filter cap TYPEs to choose :!:

Kevin

 

[khstudio]

[quote author="Purusha"][quote author="bellyflop"][quote author="khstudio"]500k reverse Audio Taper Pots
Please help if you have a source with a decent price :!:
[/quote]What are you looking to spend? Small Bear has them.[/quote]


Hey, is this the same thing?

http://www.banzaieffects.com/Alpha-16mm-FS-500k-REV-log-pr-17321.html[/quote]

YES :thumb:

That's KILLER... you guys also have a good (cheap) source.

K

 

[Purusha]

Great!

Have you estimated the cost per channel for the full version? OK, without the case...