Simple EQ for Neve 1290

[Spencerleehorton]

right i think i have worked out the cap values for the following:

600hz = 53nf
7000hz = 4.5nf
12000hz = 2.6nf

is there a way to narrow the width of the cut? or is it just a shelf?
for kick drum i would like to be able to cut mid at say 500-600hz
for snare i would like to be able to shelf the bottom and the top giving it a mid boost essentially, if this is possible?

 

[ruffrecords]

right i think i have worked out the cap values for the following:

600hz = 53nf
7000hz = 4.5nf
12000hz = 2.6nf

is there a way to narrow the width of the cut? or is it just a shelf?
for kick drum i would like to be able to cut mid at say 500-600hz
for snare i would like to be able to shelf the bottom and the top giving it a mid boost essentially, if this is possible?

This is a high pass filter so it cuts below the frequency. Cutting below 7K and 12K does not make a lot of sense.  Easier to think of it as a bass cut. Perhaps you want to cut above those frequencies? That would be a low pass filter or a treble cut.

Mid cut needs an inductor and a capacitor and start to make things a little complex. These filters, high pass, low pass and mid cut, work well in isolation but it is not so easy to combine. Not really a simple EQ any more.

Cheers

Ian

 

[Spencerleehorton]

Hi Ian,

ok so low cut (high pass) is good and i have those bits here so im going to try it.
would you suggest anything for the mid boost/cut and the treble boost/cut, it doesn't have to be that simple, just not too complex.

regards

Spence.

 

[ruffrecords]

Hi Ian,

ok so low cut (high pass) is good and i have those bits here so im going to try it.
would you suggest anything for the mid boost/cut and the treble boost/cut, it doesn't have to be that simple, just not too complex.

regards

Spence.

As soon as you ask for boost it is a whole other ball game. To do active boost needs an additional amplifier. Do to it passively will lose signal level, some of which you may be able to recover by increasing the gain elsewhere but others have cautioned against that. otherwise you have to accept the gain loss or add another amplifier. If you are prepared to take a gain hit of 15dB then you could use my REDD EQ design or my Helios 69 design, both of which are passives and give top, bottom and mid boost/cut.

Cheers

Ian

 

[Spencerleehorton]

I think i'm prepared to go active, just want to try and keep it fairly simple as i only really need certain frequencies to boost or cut.

 

[ruffrecords]

I think i'm prepared to go active, just want to try and keep it fairly simple as i only really need certain frequencies to boost or cut.

In which case something like the API 553 would do you. Single chip, 3 band active EQ. There was a long groupdiy thread about API EQs that may be worth exploring:

https://groupdiy.com/index.php?topic=12161.0

Cheers

Ian

 

[Spencerleehorton]

Thanks Ian that looks much better! I will get busy after xmas!!!

 

[Spencerleehorton]

So this is the schematic, but need to adjust this to accommodate switches for different frequencies.

 

[Spencerleehorton]

I have some spare 2520 DOA for this and could wind my own 2503 transformer, I can make my own pcb.

 

[Spencerleehorton]

A few questions, is uH a Henry? As in 1H = 1uH?

Also what is the bypass switch? I'm not familiar with one with 12 poles?

Regards

Spence.

 

[3nity]

Nah...you have 1uh or 1h...different.

 

[ruffrecords]

A few questions, is uH a Henry? As in 1H = 1uH?

Also what is the bypass switch? I'm not familiar with one with 12 poles?

Regards

Spence.

uH stands for micro Henry, one millionth of a Henry. mH stands for milli Henry , one thousandth of a Henry.

Cheers

Ian

 

[Spencerleehorton]

Thanks again Ian,
i seem to have found this

http://www.ebay.co.uk/itm/281770277470?var=580773039783

which could hopefully do for the 100mH inductor but cant seem to find a 1H inductor?
any ideas please?

i have the 2520 already built and im printing out then etching the pcbs, i have the 10k pots and will need to order some 4PDT switches.
i also have plentiful DPDT switches for selecting the frequencies.
I have a spare nickel lam transformer which i can wind as a 2503 to experiment!!

regards

Spence.

 

[Spencerleehorton]

or am i getting the value wrong?

on the schematic it looks like it says 1hy and 100mhy?

 

[Spencerleehorton]

i can see from a previous post Ian that you got one of these

http://www.banzaimusic.com/Wilco-1H.html

did it turn out to be any good or better to wind my own?

looks perfect size wise.

regards

Spence.

 

[Spencerleehorton]

this is what ive got so far for the BOM

API-553 EQ Build

BOM

Axial Lead inductor 1H - http://www.banzaimusic.com/Wilco-1H.html - for Low Shelf
100mH Inductor - ebay £1.50 or less - for Mid Shelf
2503 transformer
4PDT latching push switch
2520 DOA
3 x 10k Lin pots
3 x control knobs

1 x XLR socket
1 x Jack Socket

Resistors
4 x 10k
2 x 27k
47R
680R
3.9k
1.3k
1.8k

Capacitors
2 x 180pf
470uf/63v
0.039uf
0.033uf
470uf/16v
100uf/16v
4.7uf/16v

Diodes
2 x 2161 CR2 - can i use 1N4004?
DS1 AL209 - can i use 1N4004?


please correct anything that I've got wrong!!!!

 

[ruffrecords]

Thanks again Ian,
i seem to have found this

http://www.ebay.co.uk/itm/281770277470?var=580773039783

which could hopefully do for the 100mH inductor but cant seem to find a 1H inductor?
any ideas please?

You need to be careful selecting cheap inductors because they often use thin wire and have a high resistance which will affect the shape of the EQ. The one you linked to do not specify its resistance. You really need one with a resistance of less than 100 ohms like this one from Farnell:

http://uk.farnell.com/bourns-jw-miller/rl181s-104j-rc/choke-100000uh-9ma-5-0-09mhz/dp/1693317

For the 1H you probably need to go to Audiomaintenance.com and look for a Carnhill VTB9042

i have the 2520 already built and im printing out then etching the pcbs, i have the 10k pots and will need to order some 4PDT switches.
i also have plentiful DPDT switches for selecting the frequencies.
I have a spare nickel lam transformer which i can wind as a 2503 to experiment!!

regards

Spence.

You do not have to use a 2520, any good op amp will do. Also, as you are in the unbalanced signal path of the mic pre, you do not need the output transformer but you will need to tweak the gain so overall it is unity with the controls centred.

If you look at the Audiotronics thread in Technical info you will see variations on this same EQ but including HPF and LPF

https://groupdiy.com/index.php?topic=51783.0

In particular you should find the 110A schematic interesting.

Cheers

Ian

 

[ruffrecords]

i can see from a previous post Ian that you got one of these

http://www.banzaimusic.com/Wilco-1H.html

did it turn out to be any good or better to wind my own?

looks perfect size wise.

regards

Spence.

To be honest I was not particularly impressed, mainly because I could not get the EQ to work. Wehter this was the inductor or a mistake of mine I never did find out.

Cheers

Ian

 

[Spencerleehorton]

how about this?

http://www.ebay.co.uk/itm/6-pairs-NEOSID-RM8-L2-AL630-ferrite-core-pair-23mm-x-8mm-deep-pot-/391624941723?hash=item5b2eaa609b:gSoAAOSwB09YLH2D

i have a winding machine, not familiar with how this is wound but it looks like a bobbin goes inside?

 

[ruffrecords]

how about this?

http://www.ebay.co.uk/itm/6-pairs-NEOSID-RM8-L2-AL630-ferrite-core-pair-23mm-x-8mm-deep-pot-/391624941723?hash=item5b2eaa609b:gSoAAOSwB09YLH2D

i have a winding machine, not familiar with how this is wound but it looks like a bobbin goes inside?

Those look like standard RM8 size cores available from many places. You wind onto a core which fits inside. The two halves are usually then held together with clips.

Cheers

Ian