API-553 Build 3 band with switchable frequencies

[Spencerleehorton]

Hi all,

Though I'd document my API-553 build, want to make my own pcbs, inductors and psu.
Want to check BOM is good and also talk about how to put in switchable frequencies for Low, mid and treble.

 

[Spencerleehorton]

2x 27k
1x 1.3k
1x 1.8k
1x 680R
1x 3.9k
3x 10k
1x 47R

CR1 2161 - 1N4007
CR2 2161 - 1N4007
DS1 AL209 - LED
2x 100uf / 16v
1x 470uf / 16v
1x 500uf / 6v
1x 5uf / 16v

0.033uf
0.039uf
2x 180pf
3x 10k pots

2520 doa

100mh inductor
1H inductor

 

[emrr]

Keep in mind if you want the shapes to stay the same, you need to also switch inductors.  May not matter. 

 

[Spencerleehorton]

Im populating boards and not exactly sure I've got all values correct if anyone could check please?
also if anyone could be specific in what i need to be able to switch frequencies.
also i would like a HPF and LPF if possible.

 

[Spencerleehorton]

schematic im working from

 

[Spencerleehorton]

this is what ive done with the layout, need it checked!!!

also ive put R14 in red as it doesnt seem to be included anywhere?

also what could i use to replace the 2161 Diodes and the AL209 diode?

Also is there a pot for the gain trim or is that just a link put in?

 

[Spencerleehorton]

Im wanting to put this within a Neve Pre Amp, which is my Xbox Neve project, if anyone could help me talk about connecting it please, as i think i can do it without the transformer being installed?

 

[iprovlek]

Is this will be available for some etching Spence?

 

[Spencerleehorton]

Yes thats what i've done dude, i've etched my own and going to wind my own inductors!!
i'll post up the etch image as ive fattened up the tracks, just need to make sure the circuit works!!!

 

[iprovlek]

Great Spence!

So your inductors will be for sale for this project!?

 

[Spencerleehorton]

Yes if there is enough interest I can make some available, any idea of what price you would think?

 

[iprovlek]

I dont know!!!

Suggest a price Spence!!! You are the boss!!!

 

[Spencerleehorton]

Well at a guess how would £25 for the 100mh and £30 for the 1H sound?

Also I'm interested in this picture as I can see three way switches with caps on each side for selecting frequencies of each band, the question is what value caps to use?

 

[Spencerleehorton]

I'm also happy to use lorlins to select frequencies, rather than switches.

 

[Spencerleehorton]

Right i'm all wired up as per the 553 schematic, just waiting for the inductors to arrive and then i'll wind them.
Im installing these within a Neve 1290 preamp so just need to check exactly how i would connect as not going to use transformer, as already have transformer in Neve 1290 preamp.
Now to sort preamp and psu, need to regulate 24v to 15v with 7815 and have -15v from 7915 regulator, 24v feed to preamp and 48v for phantom.
could anyone suggest a way of selecting different frequencies on each band please?

 

[iprovlek]

Spence maybe this can help you it is under the pic!!!

https://groupdiy.com/index.php?topic=36522.0


Eq looks great and Lorlin can be great instead pots!!!

 

[Spencerleehorton]

this i think, is more on the money:

MF

3Khz      2,7nF
2,5Khz  3,9nF
2Khz      6,3nF

LF

150Hz    1µF
220Hz    0,5µF

HF

10Khz    370pF
12Khz    300pF

 

[Spencerleehorton]

found this, which gives me a better idea.

 

[Whoops]

The 550B has switchable frequencies,
check if the schematic is useful to you

 

[Whoops]

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