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Project Specific Discussions => Filters/Equalizers => Topic started by: Spencerleehorton on January 13, 2017, 02:44:00 AM

Title: API-553 Build 3 band with switchable frequencies
Post by: Spencerleehorton on January 13, 2017, 02:44:00 AM
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.
Title: Re: API-553 Build 3 band with switchable frequencies
Post by: Spencerleehorton on January 13, 2017, 04:14:16 AM
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
Title: Re: API-553 Build 3 band with switchable frequencies
Post by: EmRR on January 13, 2017, 08:49:23 AM
Keep in mind if you want the shapes to stay the same, you need to also switch inductors.  May not matter. 
Title: Re: API-553 Build 3 band with switchable frequencies
Post by: Spencerleehorton on January 13, 2017, 12:14:34 PM
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.
Title: Re: API-553 Build 3 band with switchable frequencies
Post by: Spencerleehorton on January 13, 2017, 12:37:07 PM
schematic im working from
Title: Re: API-553 Build 3 band with switchable frequencies
Post by: Spencerleehorton on January 13, 2017, 12:38:00 PM
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?
Title: Re: API-553 Build 3 band with switchable frequencies
Post by: Spencerleehorton on January 13, 2017, 12:43:21 PM
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?
Title: Re: API-553 Build 3 band with switchable frequencies
Post by: iprovlek on January 13, 2017, 12:46:10 PM
Is this will be available for some etching Spence?

Title: Re: API-553 Build 3 band with switchable frequencies
Post by: Spencerleehorton on January 13, 2017, 12:48:26 PM
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!!!
Title: Re: API-553 Build 3 band with switchable frequencies
Post by: iprovlek on January 14, 2017, 10:02:50 AM
Great Spence!

So your inductors will be for sale for this project!?
Title: Re: API-553 Build 3 band with switchable frequencies
Post by: Spencerleehorton on January 14, 2017, 11:25:04 AM
Yes if there is enough interest I can make some available, any idea of what price you would think?
Title: Re: API-553 Build 3 band with switchable frequencies
Post by: iprovlek on January 14, 2017, 12:35:48 PM
I dont know!!!

Suggest a price Spence!!! You are the boss!!!
Title: Re: API-553 Build 3 band with switchable frequencies
Post by: Spencerleehorton on January 16, 2017, 02:33:48 AM
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?
Title: Re: API-553 Build 3 band with switchable frequencies
Post by: Spencerleehorton on January 16, 2017, 02:45:35 AM
I'm also happy to use lorlins to select frequencies, rather than switches.
Title: Re: API-553 Build 3 band with switchable frequencies
Post by: Spencerleehorton on January 16, 2017, 09:04:25 AM
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?
Title: Re: API-553 Build 3 band with switchable frequencies
Post by: iprovlek on January 16, 2017, 03:24:15 PM
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!!!
Title: Re: API-553 Build 3 band with switchable frequencies
Post by: Spencerleehorton on January 16, 2017, 03:47:02 PM
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

Title: Re: API-553 Build 3 band with switchable frequencies
Post by: Spencerleehorton on January 16, 2017, 04:03:17 PM
found this, which gives me a better idea.
Title: Re: API-553 Build 3 band with switchable frequencies
Post by: Whoops on January 16, 2017, 10:30:55 PM
The 550B has switchable frequencies,
check if the schematic is useful to you

Title: Re: API-553 Build 3 band with switchable frequencies
Post by: Whoops on January 16, 2017, 10:31:43 PM
.
Title: Re: API-553 Build 3 band with switchable frequencies
Post by: Spencerleehorton on January 17, 2017, 02:19:52 AM
Bit too complicated for me! I'm just gonna keep mine nice and simple.
Title: Re: API-553 Build 3 band with switchable frequencies
Post by: iprovlek on January 17, 2017, 11:50:45 AM
You right Spence!

Isnt be good to put 2520 opamp instead that opa604 chip!!!


That would be great!!!

What you think Spence!!!
Title: Re: API-553 Build 3 band with switchable frequencies
Post by: Spencerleehorton on January 17, 2017, 02:12:55 PM
Yes that's what I've done I've used the 2520, but I think that other design uses opamp as input buffer/gain.
Title: Re: API-553 Build 3 band with switchable frequencies
Post by: Spencerleehorton on January 19, 2017, 12:25:39 PM
This is what I'm picking up tomorrow

RM8 N48 Al400 (Epcos)

RM8 3H1 Al630 (Ferroxcube), 3H1 is an equivalent material

Need to confirm winds next, I think I read  1260 winds for the 1H and also read to overwind a little.
And 400 winds for the 100mH.
Could anyone help confirm this and know how much to overwound? (1280 for 1H and 491 for 100mH)
Title: Re: API-553 Build 3 band with switchable frequencies
Post by: Spencerleehorton on January 19, 2017, 05:21:10 PM
It is announced as Al630, so you need 1260 turns for 1H. Cross-section is about 28mm², which indicates a maximum square-section of wire of 0.022 mm² resulting in a diameter of 0.14mm.
Mean Length Turn is 42mm. Closest gauge is 0.125mm (AWG36), resulting in a DC resistance of about 75 ohms.
You would need only 400 turns for the 100mH, for a DCR of about 25 ohms.
Beware that adjusting the final value needs to be done in-circuit, checking the actual circuit's response. Most inexpensive LC-meters give very inaccurate values. If you need super-accuracy, you should wind a few percent more turns than the calculation and adjust for teh final value. Also beware that properly setting the two halves of the core is important; there could be as much as 5% variation between an not-too-well seated core and one that's properly set. You have to rub them against each other.
Title: Re: API-553 Build 3 band with switchable frequencies
Post by: Spencerleehorton on January 20, 2017, 08:39:54 AM
right,

I've wound a few inductors now and got some 1H and 100mH, what sort of tolerance is acceptable for these inductors? 3-5%
if so that would give 95mH - 105mH and 950mH - 1050mH, mine at the moment ive wound at 103mH and 1025mH.
should this be ok?

regards

Spence.
Title: Re: API-553 Build 3 band with switchable frequencies
Post by: Spencerleehorton on January 21, 2017, 04:25:16 AM
from another source these first figures look really good, so im going to put it all together and do some testing inside a Neve 1290 preamp.
Title: Re: API-553 Build 3 band with switchable frequencies
Post by: nielsk on January 22, 2017, 11:13:44 AM
Very easy to use a center off toggle to have 2 freqs per band with a center off...
Title: Re: API-553 Build 3 band with switchable frequencies
Post by: Indecline on January 25, 2017, 06:43:23 PM
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

With the values being so close with such a wide Q, you wont hear that much of a difference when you switch frequencies. I modified my 553's with a decade smaller capacitor (I think!) on the switches. You'll lose gain and the Q tightens a lot, but it's a decernable difference that has come in handy a few times.. at least now my 553's get used more often after the modification  :P
Title: Re: API-553 Build 3 band with switchable frequencies
Post by: Spencerleehorton on January 26, 2017, 11:05:16 AM
could you suggest what figures you think maybe which would work better?
Title: Re: API-553 Build 3 band with switchable frequencies
Post by: Spencerleehorton on January 26, 2017, 11:07:03 AM
Also as the winding of the inductors went so well, i went back to my supplier and have done another deal which could put these inductors out professionally wound at £15 each!! would need to be a fairly big order for this to happen though.

Anyone interested?
Title: Re: API-553 Build 3 band with switchable frequencies
Post by: Indecline on January 27, 2017, 11:08:33 AM
could you suggest what figures you think maybe which would work better?
I'll check over the weekend what values I used  :)
Title: Re: API-553 Build 3 band with switchable frequencies
Post by: Spencerleehorton on January 27, 2017, 01:25:25 PM
thanks very much!!!
i just gotta build a stable psu for this as having problems altering this ssl 9k psu to try and accomodate 48v, 24v, 15v and -15v.
Title: Re: API-553 Build 3 band with switchable frequencies
Post by: Spencerleehorton on January 28, 2017, 12:47:14 PM
this is going to be my psu.
Title: Re: API-553 Build 3 band with switchable frequencies
Post by: Spencerleehorton on January 29, 2017, 12:07:39 PM
This is what i will be making for this and the Neve Preamp.
Title: Re: API-553 Build 3 band with switchable frequencies
Post by: Spencerleehorton on February 05, 2017, 03:56:41 PM
Thought I'd put up a pic of the inductors.
Title: Re: API-553 Build 3 band with switchable frequencies
Post by: Spencerleehorton on May 15, 2019, 10:47:18 AM
Had another little look at this today and will be building +15/-15v Psu to see if I can see how these sound.
Title: Re: API-553 Build 3 band with switchable frequencies
Post by: Spencerleehorton on May 17, 2019, 08:00:54 AM
Thinking of using a 4 pole lorlin for the bypass switch so I can wire off the pcb, rather than get a 4pdt switch, but might order a couple as it’ll be easier.
Title: Re: API-553 Build 3 band with switchable frequencies
Post by: Spencerleehorton on May 18, 2019, 02:55:34 PM
Making the +\- 15v pcb, hopefully populate and test tomorrow!!!
Title: Re: API-553 Build 3 band with switchable frequencies
Post by: ruffrecords on May 18, 2019, 04:35:38 PM
|I see you ended up with simple toggles to select two frequencies for each band. There is a simple way to make this three frequencies using toggle switches with a centre off position.

You wire the first cap right across the switch so when the switch is in the centre off position this cap determines frequency. This will be the highest of the three frequencies. Then you use the other two 'on' positions of the toggle to add two different value caps in parallel with the first one. Both these frequencies will below the first because the total capacitance is increased. I use this method in my new REDDPLUS EQ to get three frequencies on each of the three bands.

Cheers

ian
Title: Re: API-553 Build 3 band with switchable frequencies
Post by: Spencerleehorton on May 19, 2019, 01:27:14 AM
Perfect thank you Ian, I need to get these powered up first before any mods but as soon as I do I will try what you have said.
Title: Re: API-553 Build 3 band with switchable frequencies
Post by: Spencerleehorton on May 19, 2019, 08:46:38 AM
Don’t know if it’s possible or a stupid question but all the Psu schematics I’ve seen run off centre tapped txf.
I seem have a bit of confusion over this part of the circuit.
Is it possible to do a positive and negative feed Psu from just 2 X Ac feeds rather than centre tapped? (3 terminals)

Btw I have a 24vac toroidal and want to feed either LM317/337 or 7815/7915.
Title: Re: API-553 Build 3 band with switchable frequencies
Post by: Spencerleehorton on May 19, 2019, 09:22:09 AM
Also I’m using 5k pots rather than 10k, should this be an issue?
Title: Re: API-553 Build 3 band with switchable frequencies
Post by: Spencerleehorton on May 24, 2019, 03:05:11 AM
What current does each channel of these pull?
Title: Re: API-553 Build 3 band with switchable frequencies
Post by: Spencerleehorton on May 25, 2019, 01:28:02 PM
Right, finally had a bit of success with one pcb!
I’m getting good voltages and all pots work, even though they are 5k rather than 10k.
I’m going to try and connect these to the Neve 1290 and see how they sound.
Title: Re: API-553 Build 3 band with switchable frequencies
Post by: Spencerleehorton on May 26, 2019, 05:51:54 AM
This is the output waveform from the 553 being put just before the 1166 output txf in bypass.
Title: Re: API-553 Build 3 band with switchable frequencies
Post by: Spencerleehorton on May 26, 2019, 05:53:10 AM
This is with the 553 Engaged, you can see the waveform distorts.
Title: Re: API-553 Build 3 band with switchable frequencies
Post by: Spencerleehorton on May 27, 2019, 01:50:21 AM
success now, connected to P and L within Neve 1290 and get lovely waveform, circuit works!!!
Title: Re: API-553 Build 3 band with switchable frequencies
Post by: Zebra_PD on July 06, 2019, 11:51:53 AM
Great work!! Any chance you might make the schematics/drawings available to the forum if u are successful? :)

Anyway will follow this build with great interest. Planning to design n build some stereo EQs with the option of both "modern" and "vintage" API sound in 19" format. Sort of what API done with the API 5500 but based on the 553 to lower the cost and make an easier build.

Title: Re: API-553 Build 3 band with switchable frequencies
Post by: Spencerleehorton on July 06, 2019, 05:07:55 PM
All the documents are on the first page, that’s what I used to do pcb.
I have made a few changes when looking at schematic, which is also there on the first page.
Still haven’t fully finished the faceplate for the 1073-553, but will do in a couple of weeks, busy time atm!!!
Title: Re: API-553 Build 3 band with switchable frequencies
Post by: Zebra_PD on July 08, 2019, 01:59:59 AM
All the documents are on the first page, that’s what I used to do pcb.
I have made a few changes when looking at schematic, which is also there on the first page.
Still haven’t fully finished the faceplate for the 1073-553, but will do in a couple of weeks, busy time atm!!!

Haha sorry, for some reason (prob bad cellphone connection in the woods or a too tired brain) I did not see any attachment when I looked at the first posts the first time around. Now I clearly see them now.

And thx you for sharing this build with the rest of us :)