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

[bluezplaya]

And one more thing I SWEAR :roll: what is the part number for the DPDT switch?

 

[funkdrmr]

[quote author="bluezplaya"]And one more thing I SWEAR :roll: what is the part number for the DPDT switch?[/quote]

Here's the digikey p/n that I ordered. I think Kevin provided it earlier in this thread as well.

401-1223-ND

 

[Neeno]

Hi Guys !
I just received a dozen pots from Colin (thank you).
I have to say that the rotation feel is better than the pots I've got from Omeg before.

Yesterday i measured the resistance in the middle position of the small batch that i've got, 11 of them are around 54-57k but one is out of the ball-park and it measures 70k :roll:

How can i proceed ?
Anyone knows how can I modify the circuit to get a Gain of 1 having 70k in the middle position of the pot ?

 

[Harpo]

Hi Neeno,

if you don't simply want to displace the knobmarker, have a look at this Excel sheet .

-Harpo

 

[Neeno]

Thank you Harpo !
I've got those pots from Colin, displacing the knob would not be a problem but since they are center detented i'll try to tweak the ciruit...

 

[laiben]

my pots are the same... they are close to 60K instead of 47K..

 

[khstudio]

[quote author="Neeno"]Hi Guys !
I just received a dozen pots from Colin (thank you).
I have to say that the rotation feel is better than the pots I've got from Omeg before.

Yesterday i measured the resistance in the middle position of the small batch that i've got, 11 of them are around 54-57k but one is out of the ball-park and it measures 70k :roll:

How can i proceed ?
Anyone knows how can I modify the circuit to get a Gain of 1 having 70k in the middle position of the pot ?[/quote]

If your getting 54-57k, I'd say you're in good shape.
If you read back a little, HARPO mentions the Calculated (not exactly the original - which mine measured around 47-48k average) center point, the circuit SHOULD be... I think it's around 50k-51k.
I also think Peter said this to me in an email WAY back.
So, you can adjust your 5.6k resistors & be in very good shape. :wink:

I'd say a CENTER POINT anywhere around 48k - 52k would be good.:idea:

 

[laiben]

[quote author="khstudio"][quote author="Neeno"]Hi Guys !
I just received a dozen pots from Colin (thank you).
I have to say that the rotation feel is better than the pots I've got from Omeg before.

Yesterday i measured the resistance in the middle position of the small batch that i've got, 11 of them are around 54-57k but one is out of the ball-park and it measures 70k :roll:

How can i proceed ?
Anyone knows how can I modify the circuit to get a Gain of 1 having 70k in the middle position of the pot ?[/quote]

If your getting 54-57k, I'd say you're in good shape.
If you read back a little, HARPO mentions the Calculated (not exactly the original - which mine measured around 47-48k average) center point, the circuit SHOULD be... I think it's around 50k-51k.
I also think Peter said this to me in an email WAY back.
So, you can adjust your 5.6k resistors & be in very good shape. :wink:

I'd say a CENTER POINT anywhere around 48k - 52k would be good.:idea:[/quote]

so if the center point is 60K, even the 5.6k resistor is removed, it is still too much resistance? is the difference audible?

:roll:

 

[khstudio]

#1
I'm not so sure you can or SHOULD completely remove the 5.6k...
I'd at least put something low in there...10 or 12 ohms maybe.
Someone else with have to give you more technical reasons.

Not being fully centered will just give you a hair more (or less) volume at Center, compared to Bypassed... I wouldn't call it a big deal & IT WILL NOT effect the "sound" of the EQ AT ALL.

 

[Sorr]

Has anyone experimented with different EQ capacitors?
Any preferences?

Sorr

 

[MrZpliff]

[quote author="khstudio"]#1
I'm not so sure you can or SHOULD completely remove the 5.6k...
I'd at least put something low in there...10 or 12 ohms maybe.
Someone else with have to give you more technical reasons.

Not being fully centered will just give you a hair more (or less) volume at Center, compared to Bypassed... I wouldn't call it a big deal & IT WILL NOT effect the "sound" of the EQ AT ALL.[/quote]

I've bypassed the resistors on some of my pots. Seem to work fine, though I've only tested it for about half an hour. Haven't had the time to rack it up yet :sad:
There might be some reason not to bypass them completely though. But that's a little above my head :?

 

[Harpo]

Hi MrZspliff,

you shurely have seen this Excel sheet ?

This Resistor is Part of R in and sets the max.gain of this inverting summing stage, varying between -20dB to +20dB. Voltage gain -AV=56k2/(R potentiometer + 5k62) = R30 / (R42 + R43) for the 40Hz band, ... or R30 / (R38 + 39) for the 650Hz band. If you bypass this series resistor, you'll overload this summing stage, as the max.gain setting try to reach infinity, only limited by rail voltages.

-Harpo

 

[MrZpliff]

Thank's for the information. :thumb:
Is that a problem in reality ? I doubt I'll ever cut or boost more than about 5 dB with this EQ. Probably no mare than a few dB's... :?

 

[Harpo]

[quote author="MrZpliff"]Thank's for the information. :thumb:
Is that a problem in reality ? I doubt I'll ever cut or boost more than about 5 dB with this EQ. Probably no mare than a few dB's... :?[/quote]
Might get a problem when boosted accidently by whoever else dials your potentiometers.
If all pots have nearly the same value at center, simply change the feedback resistor R30 to the resistor value at center ie. 65k or whatever yours have + the series resistor 5k62), giving 70k62 for previous example and change the resistor R48 for bypass to this same value.
-Harpo

 

[MrZpliff]

[quote author="Harpo"][quote author="MrZpliff"]Thank's for the information. :thumb:
Is that a problem in reality ? I doubt I'll ever cut or boost more than about 5 dB with this EQ. Probably no mare than a few dB's... :?[/quote]
Might get a problem when boosted accidently by whoever else dials your potentiometers.
If all pots have nearly the same value at center, simply change the feedback resistor R30 to the resistor value at center ie. 65k or whatever yours have + the series resistor 5k62), giving 70k62 for previous example and change the resistor R48 for bypass to this same value.
-Harpo[/quote]

Thank's again. I think I get it.
Need to check with the schematic.

 

[idylldon]

Anyone using Peter's power supply board with the NightEQ? Should I use an 18-0-18 transformer or a 15-0-15? I know someone mentioned that running the 18 volt tranny made the regs run pretty hot.

Thanks,
--
Don

 

[khstudio]

[quote author="idylldon"]Anyone using Peter's power supply board with the NightEQ? Should I use an 18-0-18 transformer or a 15-0-15? I know someone mentioned that running the 18 volt tranny made the regs run pretty hot.

Thanks,
--
Don[/quote]

I tried to use an 18v-0-18v tranny in mine & it DID make the regs hot.... not to mention it made the EQ "Sound" different... & not in a good way.
I used a 15-0-15 instead & it worked GREAT & even sounded better to my ears (+ my friend & the guy I was building it for)... go figure. :?

15v trannys look a little higher when unloaded (how much depends on how big or much current the tranny has to offer)
But 15v X 1.4v (diode Rectifier) you get = 21volts
Even loaded down a little this has worked well for me & should be fine to get a Regulated 18v DC!
If your worried, just knock your DC down a little... like 17v & you'll be fine.

 

[idylldon]

Thanks, Kevin. I'll go with a 15-0-15.

Cheers,
--
Don

 

[Grooveteer]

I have so much to learn...

I'm done stuffing the boards, and I must have done somehing wrong here. Both units pass audio but al a very low volume and it sounds as if I'm going trough a low-pass filter. Really boomy. The EQ does work; but is unusable because of the issues above. I'm a real noob at this, does anyone have a clue on where to start looking? Could it be the wiring of the Lorlin?

Thanks so much.

Cheers,

G

 

[dagoose]

[quote author="Grooveteer"]I have so much to learn...

I'm done stuffing the boards, and I must have done somehing wrong here. Both units pass audio but al a very low volume and it sounds as if I'm going trough a low-pass filter. Really boomy. The EQ does work; but is unusable because of the issues above. I'm a real noob at this, does anyone have a clue on where to start looking? Could it be the wiring of the Lorlin?

Thanks so much.

Cheers,

G[/quote]

Have you checked the balnced/unbalanced jumper together with the balnced/unbalbced connection? I had the same problem at first, distorted when i added a couple of DB of eq boost and very boomy and soft.
If you have the jumpers in for balnced, connect it balanced