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

[bieckmusic]

hey shot,

Sounds like you're standing in front of the butt-kicking machine with a handful of quarters. 

It happens all the time glad you found it!!



Greg

 

[shot]

Yeah! I try to be as detailed as possible and this is something I never imagined could happen. A flick of a second when writing labels and there it goes. Damn!
:-[

 

[frazzman]

So hypothetically, if I left a pot disconnected from the circuit - what would we expect the result to be - for example if the 40hz pot was omitted would this frequency sit at 0db, -5db etc. will there be a boost/cut effect with a pot omitted ? Reason I ask is I managed to mess up a few pots in the process of trying to jam them into my very congested front panel real estate and now I'm waiting for some new ones from aml. In the meantime I left out the damaged pots but the circuit sounds like it's lost a bit of low end - at the moment the sub pots are disconnected and 650hz on the right channel. Any thoughts ?

 

[Harpo]

Cut effect for the omitted bands. Substitute the omitted variable resistance (the 470K rev.log. pot wired as rheostat) by 47K...50K resistor.

 

[pieca]

hi!

I'm following actively this topic from weeks…

This is my build :

All pots are stepped with 0.5 Db steps with 23p rotary switches (from -5.5Db to +5Db). Thanks harpo for your exell file 

I don't know if it works yet… I have to bring it to the studio for test, but so far so good : no smoke yet  ;D

I have also to deal with the amber led's resistor values, they are killing my eyes (no issues with the red ones)


I'm planing to add the overload circuitry from there  (thanks harpo again) :
http://www.khstudio.us/DIY%20PICs/CLIP%20CIRCUIT.bmp

just got a question :
on the peak schematic, signal is taken after pin 7 of U4
on my board done with Petter Cornell's PCB V2 1-6-7 it seems that the only pin 7 going to 470uf condenser ant then a 47r resistor (R29) is U6…
Anyone ever implement clip circuitry in their build?
Any help will be really appreciated!

 

[Harpo]

I have also to deal with the amber led's resistor values, they are killing my eyes (no issues with the red ones)

increase current limiting resistor to decrease current flowing for your probably amber high-efficiency-LED.

on the peak schematic, signal is taken after pin 7 of U4
on my board done with Petter Cornell's PCB V2 1-6-7 it seems that the only pin 7 going to 470uf condenser ant then a 47r resistor (R29) is U6…

Either after DC blocking 470uF cap connecting to pin6 of the NE5534 summing amp or after corresponding cap connecting to pin7 of the following NE5532 inverter.
Consider to increase the value of R200 in order to decrease sensivity of the clip indicator circuit.

 

[pieca]

Consider to increase the value of R200 in order to decrease sensivity of the clip indicator circuit.

I've read somewhere in this post than the original R200 value was 46.4K instead of 4.64k, will try to start with this…

 

[frazzman]

Cut effect for the omitted bands. Substitute the omitted variable resistance (the 470K rev.log. pot wired as rheostat) by 47K...50K resistor.

Thanks Harpo.

Also - if I had a level difference present with both channels are engaged, where would be the place to start? Is there a resistor I can change to try and match the levels. From what I can tell it looks like left channel is 3db louder than right. I will do some more testing when the new pots arrive. Both channels are level in bypass though. Cheers

 

[Harpo]

Also - if I had a level difference present with both channels are engaged, where would be the place to start? Is there a resistor I can change to try and match the levels. From what I can tell it looks like left channel is 3db louder than right. I will do some more testing when the new pots arrive. Both channels are level in bypass though.

3dB difference only in bypass mode? tweak R48 for input level=output level. 3dB difference in both bypass mode and all bands centered for +/-0dB? tweak R30. If this level imbalance is frequency dependant, look out for same resistor and cap values at the bandwidth limited gain stages.

 

[frazzman]

Also - if I had a level difference present with both channels are engaged, where would be the place to start? Is there a resistor I can change to try and match the levels. From what I can tell it looks like left channel is 3db louder than right. I will do some more testing when the new pots arrive. Both channels are level in bypass though.

3dB difference only in bypass mode? tweak R48 for input level=output level. 3dB difference in both bypass mode and all bands centered for +/-0dB? tweak R30. If this level imbalance is frequency dependant, look out for same resistor and cap values at the bandwidth limited gain stages.

Thanks Harpo, sorry to clarify the level difference between channels is not in bypass but when both channels are engaged. It isn't frequency dependent. Do the same principals apply ? I had checked each resistor value for each channel when stuffing but there is apparently some difference resulting in the level difference. I checked the balanced/unbalanced jumpers too and both channels have the expected cutting / boosting behaviour

 

[Harpo]

..the level difference between channels is not in bypass but when both channels are engaged. It isn't frequency dependent.

with missing pots substituted by prementioned resistors ? The stages in this 'EQ' are not filters but bandwidth limited gain stages that get summed up to a more or lesser degree to recombine for the complete audio band. If one band would be missing, this would explain the L/R imbalance, but this would be frequency dependant with most impact at the center frequency of the one side missing band. Is the sum of each half rotation rev.log.pot value + 5K62 series resistor for the +/-0dB setting the same as value of R30 ?

Do the same principals apply ?

Yepp.

I checked the balanced/unbalanced jumpers too and both channels have the expected cutting / boosting behaviour

balanced/unbalanced jumpers mixed up would be 6dB difference, not 3dB.

 

[shot]

Hey guys... another problem...

I've almost finished my build. Signal passes through, SNR is cca -100db (100hz peak, 50hz waaay below), works almost like charm!

But there's big difference in boost and cut. And it happens on all bands, both channels!
Boost is cca +16db
Cut is cca -4db

I've checked Rseries resistors and their values are good.

Where else to look?

 

[iprovlek]

Great unit Shot!

And front panel is great....

I think that the sound is great!

 

[shot]

Thanks! (Hvala Igore!)

Front panel is some sort of thick foam-ish material. I don't know it's name.
I went to buy colored plexyglass but ended up with this for cheap.
Print is regular toner transfer, same as if I was doing pcb's.
And it's acryllic varnish to protect the surface.
It's all DIY!
And the rest is... momentary switches from Studer's unknown module, my design for the flip-flop pcb to control relays that do bypass switching and turn lamps in momentary switches... and PSU... is just PSU...

 

[pieca]

hi everyone,

I need some clarifications about stepped pots and Harpo's exell sheet.
I've read all the posts, but it is not really crystal clear for me…

with stepped pots, I need to bridge all "max boost" resistors from the board (R37,39,41,43,45)

what about "max cut" resistors (R36, 38, 40, 42 44) ? Must I let them or bridge them too?

Thanks for your help 

 

[Harpo]

with stepped pots, I need to bridge all "max boost" resistors from the board (R37,39,41,43,45)

From excel sheet 'to substitute Rseries+RV' shouldn't leave a question remaining.

what about "max cut" resistors (R36, 38, 40, 42 44) ? Must I let them or bridge them too?

These are not R36,38,40,42,44 but the pots RV36,38,40,42,44.

 

[shot]

Maybe my post few days ago went under the radar...

So i humbly BUMP my question...

Can anyone help me to find the cause why my unit is boosting +16db and cutting only 4db?
On all the bands of two boards it's doing the same thing....

 

[Harpo]

Can anyone help me to find the cause why my unit is boosting +16db and cutting only 4db?
On all the bands of two boards it's doing the same thing....

This 'EQ' (it is a frequency band split summing circuit) isn't cutting like a usual filter. Non-inverting bandwidth limited gain stages don't fall below unity gain. It is the lesser boosting that is perceived as cut and this 'cut' has limits for prementioned reason.
Double check parts values and orientation. Jumpers set correctly ? Common to both boards probably will be a wrong not band specific parts value, wild guessing maybe the voltage divider R25/R24 after the debalancing stage, wrong value and/or wrong taper pots and missing or wrong output stage jumper setting. Maybe it is only me, but from your build pic I couldn't identify a single parts value and a blurry pic will only get you a blurry answer.

 

[shot]

Yes, I was also thinking that it must be some resistor or other element with wrong value.
I started checking but so far haven't found any misplaced value. Went through output part (from where EQs and bypass come together) till the output, but no luck yet. Tomorrow I'll check the rest of it.

Pics came from my mobile phone so they are too blurry. I'll try to take better pix.

 

[kogstudio]

Hey does anyone have a link and/or part # for the type of knobs that were used on the original nightpro eq3d?
I.e. the coloured top ones?
like on this page (but not for the small yellow one, I'll keep them all the same size)
http://www.pixelproaudio.com/used/mic-preamps-eqs/used/nti-nightpro-eq3d-equalizer.html

Any info much appreciated