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

[Harpo]

[quote author="Grooveteer"]Both units pass audio but al a very low volume and it sounds as if I'm going trough a low-pass filter. ... Could it be the wiring of the Lorlin?[/quote]
Hi Grooveteer,

miswiring of the lorlin is unlikly, as this "air" stage is only adding.

Turn the unit to bypass and check, if volume loss and the boomy sound remains. If so, the error resulting in boom sound is probably the tiny c13 cap across the feedback resistor R30 of the summing amp U5. Should be 22pF, not nF or uF. Loss in gain when bypassed is probably caused by a wrong resistor value. Check correct value of R1,2,3,4,26,27,30,31,47,48.

Case the unit bypassed is ok, check correct values of the caps between op-amps inverting input and their output, each value labled .1uF (=100nF). If you missed the decimal dot in front of the 1, the according lpf cutoff frequency will be 10 times lower than its hpf cutoff point in the same amp stage, resulting in boomy sound and about 15dB loss in gain.

-Harpo

 

[Grooveteer]

Harpo: You mean that 0.22 uF cap that I had there? Problem solved. Thanks man! :guinness:

To add further to my shame: Da Goose was right too. I forgot the jumpers for balanced / unbalanced. Made no difference though. (still had the wrong cap at C13, maybe that's why I could't hear the difference)

Need to do some more listening, but so far I like what I'm hearing.

Cheers,

G (Happy, happy camper)

 

[ilikeit]

hi
me too i have started a nite eq but i have a little problem
i don't know how to link the rotary switch for the AIR frequency
q 5-6 B 1 2 3 4 5 6
???
can you help please!
thanks a lot

 

[Harpo]

[quote author="ilikeit"]hi
me too i have started a nite eq but i have a little problem
i don't know how to link the rotary switch for the AIR frequency
q 5-6 B 1 2 3 4 5 6
???
can you help please!
thanks a lot[/quote]
Hi ilikeit,
have a look at the schematic. :wink:
The Lorlin switch is a 2 pole (center terminal A+B), 6 position (1-6 for pole A, 7-12 for pole B) switch. If you're not shure because of other brand or different labeling, just ohm it out.
Lorlin center terminal 'A' connects to PCB 'Q', leading to op-amp pin 1, outer Lorlin terminals 2,3,4,5,6 of section 'A' are all joined and connect to PCB '2-6', leading to the potentiometer R34, terminal 1 is not connected (for off position).
Lorlin center terminal 'B' connects to PCB 'B', leading to R6 and outer Lorlin terminals 2,3,4,5,6 of section 'B' lead to the according '2', '3',...,'6', leading to the frequency setting caps. Again terminal '1' is not connected (for off position).
This is shurely (and probably better) explained in a previous post.
-Harpo

 

[ilikeit]

hello,
I began the manufacture of my nite eq before putting my cheap I wanted to test the power I have definitely + /-18V but all my 22 ohm resistence smokes
somebody has had this probleme?
however after examination my PCB is clean

 

[khstudio]

[quote author="ilikeit"]hello,
I began the manufacture of my nite eq before putting my cheap I wanted to test the power I have definitely + /-18V but all my 22 ohm resistence smokes
somebody has had this probleme?
however after examination my PCB is clean[/quote]

You definitely have something wrong!!!
The board works.

carefully recheck everything until you find it.
You could also post some DETAILED Pictures so we can see what's going on.

 

[peterc]

If all the 22R resistors are smoking, it sounds like a dead short across the supply rails.

Disconnect the PSU & measure the resistance from the + rail to ground & the - rail to ground.

Peter

 

[ilikeit]

it s very strange...
all my resistor make 22 ohm
when I weld them on PCB, they make no more than 18 ohm
but it parried normal
when I welded all my RPSU and that I measure I acquire 32 ohm between +18 and - 18V (I took away feeding)however I have definitely look and all my soldering is clean

 

[Harpo]

[quote author="ilikeit"]it s very strange...
all my resistor make 22 ohm
when I weld them on PCB, they make no more than 18 ohm
but it parried normal
when I welded all my RPSU and that I measure I acquire 32 ohm between +18 and - 18V (I took away feeding)however I have definitely look and all my soldering is clean[/quote]
Hi ilikeit,

as Kevin already posted, a pic could help to narrow it down, so a little flying blind. Anyway, step by step..,
disconnect your supply, pull all your (maybe blown) op-amps, replace the burnt 22R resistors (32R across +/-18V rails would pull 1,125A and require >40 W rated resistors to survive) and measure resistance again between +18V connector and socket pin-8 of the dual op-amps NE5532 as well as pin-7 of the single op-amp NE5534 below the 470uF cap C15. Should read about 22R each. Same to the negative rail between -18V connector and socket pin-4 of NE5532 as well as NE5534. Case not, locate the short following the rail traces.
Between +18V and -18V connector I'd expect a value between 1M and infinity, same between +18V connector and gnd. Between -18V connector and gnd eighter a value above 1M/infinity or about 3k3, depending on position of the bypass-switch, caused by current limiting R for the LED.
Reconnecting your supply and powering up, you should check your +/-18V rail voltages at op-amp sockets pin-4 and pin-7/pin-8. If all seems OK, power down again.
Next step, check if your op-amps survived. Measure resistance between op-amp pins-8/4 for all NE5532's and between pins 7/4 for the NE5534, reading some Mohm. Case not, this op-amp is probably blown, so replace it by a new one.
Hopefully final step will be to put the the op-amps back into their sockets. Take care of the right direction and the different chip in the middle.
-Harpo

 

[ilikeit]

hi Harpo and thanks for you answer
i re checked my PCB
i have 19ohm between the +18V rail and the pin of different NE
it's identical between the -18V and the other pin
i have checked too my cheap
everything is ok
but i have always 32ohm between the + and the - 18v
i don't want plug the PSU before looking for the probleme
all idea are welcome
regards
greg

 

[peterc]

Take out the opamps, & measure the resistance between pins 8 & 4 on the 5532 & pins 4 & 7 on the 5534. They should be open cct or high resistance. Measure between 8 & gnd, 7 & gnd & 4 & gnd on the various opamps, should be fairly high resistance, above 15k or so.


Peter

 

[discobloud]

[quote author="ilikeit"]hello,
I began the manufacture of my nite eq before putting my cheap I wanted to test the power I have definitely + /-18V but all my 22 ohm resistence smokes
somebody has had this probleme?
however after examination my PCB is clean[/quote]

I'm having a similar problem. I built 4 channels(2 units) and used a 15-0-15 tranny with Peter PSU and one of the channels burns the 22R resistors. The board is clean and not sure what do to. I changed the resistors, rechecked all the connections and it burnt them again.

I'll take some photos later. Is there something I should be looking to change/replace, the other channel didn't burn.

 

[peterc]

Disco

Do the resistors burn when the IC's are taken out?

Take the IC's out of both of the channels & then do some DC voltage checking on the pins of the opamp sockets.

Peter

 

[ilikeit]

hi
peterc has right
i checked all my IC with a metrix
everything was alright
but when i placed it on the PCB i haved 22 ohm between the pin of PSU
i place one after one the IC on the PCB and each time i have checked my metrix
and i find one IC was dead
now my nite eq is good!!
:grin:

(sorry for my english )

 

[discobloud]

I figured it out. Thanks so much for the help. I'll post photos of the finished builds later.

[edit later that eve]





thanks to Kevin, PeterC, Purusha and everyone else involved. Great sounding EQ.

is this the same EQ http://electrical.com/item.php?page=5&pic=pictures/5-0.jpg

nice description

mark

 

[ChuckD]

Here's my latest build. Did it as a favor for a producer friend here in LA. He's helping me with my latest record.

I squeezed it into an old Alessis box and used parts laying around. Probably the cheapest build ever!

Not a bad EQ at all. The Air is a really cool set of bands

-ChuckD

 

[discobloud]

I'm having s small problem with one of the channels.

When I turn up the SUB pot to about 1 o'clock, the channel distorts and if i keep turning the EQ, the signal vanishes. I changed all the op amps and changed the pot in question too. Not sure what else I should be looking for. The board is clean and I checked all the solder joints too.

Also when I put it in bypass, then switch it back, it takes a 1/4 second to kick in.

photo of the build
http://img444.imageshack.us/img444/5228/img3912bg4.jpg

Thanks

Mark

 

[vertiges]

dicobloud & ChuckD, nice work guys !! :thumb:

I have to finish mine, I have to finish mine !!! :green:

ed)))

 

[matta]

Hi Guys,

I'm trying to wrap up a Night EQ build and have a couple questions. Obviously I'm aware that the pots need to be tailored to the circuit esp. if they are center deteneted and I have Harpo's GREAT spreadsheet (thanks again, you are spreadsheet king!).

The first board is done and it seems on paper to work well (not tried it in practice), sadly though on the 2nd channel one pot measures 470K but the center is pretty high at 79.1K!!!

Here are my pot values and center points

Sub = R45 = 472K = 60.31K
40 Hz = R43 = 489K = 58.83K
160 Hz = R41 = 441K = 56.35K
640 Hz = R37 = 470K = 79.10K
2.56 kHz = R37 = 442K = 57.73K

Punching the numbers into the spread sheet I get the following results.

Sub = R45 = 26,700K
40 Hz = R43 = 28,180K
160 Hz = R41 = 30,660K
640 Hz = R37 = 7,910K
2.56 kHz = R37 = 29,280K

Replace R30 and R48 with 87,010

Does that look right? So all my once 5K62's now jump to over 25K?

Also I notice the spreadsheet doesn't cater for the the 'AIR' band? What is done here with the series resistors RE trying to center the gain pot? Does it not effect the rest of the bands like the others do, for in the case of the above example it seems that any change in the center point will effect the resistors around them?

Thanks in advance!!!!

Matt

 

[Harpo]

Hi Matt,

your numbers seem right, but I don't think you'll get lucky with your 79k1 pot at center for 640Hz, resulting in about 10dB less boost for the remaining bands. (if you can't exchange it with another pot, a 330k in parallel to this pot might be a better compromise, so value of this pot/rheostat at center would be 63k8 for 193k9 total resistance).
The air band is only adding (no -dB), so a center detented pot doesn't make much sense in this place, though it won't hurt. You may try to exchange this pot as a replacement for your 640Hz band pot.
-Harpo