Studer 169 EQ in API 500 format

[kante1603]

Just wondering if you could easily put the transformer on a toggle  switch ?

Member assrael is right,too many stuff to change for a nearly inaudible difference.
I'd leave it as it is,


just my 2ct,


Udo.

 

[avieira]

My next one:

- added LED for EQ in

Hey guys/gals. I've run into a small problem while putting the finishing touches on my EQ. I'm trying to tie in an LED on the bypass switch like Holder did but am running into an issue. Attached is a pic showing how I tried to wire it. The problem is that there's an attenuation in audio signal when I wire it like this - the LED switches correctly but it corrupts my audio signal. I'm sure this is a noob mistake. Any suggestions?

 

[assrael]

It seems to me, that you are using the cold signal for the LED ground. This is not a good idea.
Wire the LED to “real” ground and use a resistor inbetween.

 

[kante1603]

Hey guys/gals. I've run into a small problem while putting the finishing touches on my EQ. I'm trying to tie in an LED on the bypass switch like Holder did but am running into an issue. Attached is a pic showing how I tried to wire it. The problem is that there's an attenuation in audio signal when I wire it like this - the LED switches correctly but it corrupts my audio signal. I'm sure this is a noob mistake. Any suggestions?

It won't work like this,seems you're mixing up switched dc for the led with the audio.
And as assrael stated you need a preresistor.
For the switch a third pole is needed to make the led work correct.


Best,


Udo

 

[avieira]

Ah ha. Thank you both assrael and Udo. I was operating under the assumption that someone else had successfully done it before me.

Cheers.

 

[kante1603]

Ah ha. Thank you both assrael and Udo. I was operating under the assumption that someone else had successfully done it before me.

Cheers.

Seems Holger used a different switch,maybe 3 or 4pole dual throw.Looks like he has cut off the last pins on the switch bottom to make it fit the pcb.So the last pins don't go through pcb holes,just the top side is used for soldering the led wires.


Best,


Udo.

 

[Trench Recordings]

What caps did you guys use in C3 C7 C9 C13 ? electrolytic in the audio path yes ? 

Which caps should be film C4 C5 C6 C11? The rest ceramic is ok ?

 

[Krcwell]

Ah ha. Thank you both assrael and Udo. I was operating under the assumption that someone else had successfully done it before me.

Cheers.

Seems Holger used a different switch,maybe 3 or 4pole dual throw.Looks like he has cut off the last pins on the switch bottom to make it fit the pcb.So the last pins don't go through pcb holes,just the top side is used for soldering the led wires.

This is what I did, got a 4 pole switch from mouser, cut off the bottom pins for the back 3 rows, and wired the led and resistor into the top pins. Works perfectly.

 

[iprovlek]

I need help guys!

I wanna use switch for changing low an high freq on this Eq !

I saw that schamtics for this mod here, but dont understand how to solder correctly to get work!?


Thanks....

 

[rmaier]

Have you checked out the thread on the pre-500 version of the EQ? I made mine with switchable highs and lows, and found it really helpful:

http://groupdiy.com/index.php?topic=33996.0

Also check the photos of my build on page 11ish of this thread for a closer look at wiring the switches.

Cheers

 

[iprovlek]

I looked to your pics!
I saw that caps are solder on PCB, and than you put other caps on Lorlin switch!? Im right!?

C4,C5 and C6 caps are on PCB!?

 

[rmaier]

Yes, C4,5,6 are on the PCB.  Its been a few years since I looked at this, so my memory is pretty foggy, but from what I recall, the mods to add a couple of extra frequencies for the low shelf were pretty easy to implement. Those are the capacitors  soldered directly on to the lower rotary swiches. More detailed information should be somewhere on the first few pages of this thread.

Ralph

 

[rmaier]

How would I go about installing switches for the 3 selectable frequencies?  I'd like to do this, but don't really know how.

Low filter: Use a single pole on-off-on toggle switch. The first "on" position connects a capacitor in parallel with C6 and the other "on" position connects another value capacitor in parallel with C6. In the middle "off" position there is C6 alone. Now you have 3 selectable frequencies.

High filter: Same idea but you need a two pole on-off-on switch since there are two capacitors which determine the frequency (C4 and C5).

Note that I have included some extra pads on the PCB to make wiring easier.

This is the mod I was trying to remember. Hope it helps. I was just using this eq the other day after not having used it for a while. I forgot how good it sounds!
Cheers.
Ralph

 

[G-Sun]

Low shelving filter +/- 15dB. Default frequency is 20 Hz as in the original circuit,
but you can select a new value for C6 from this graph to change it:
http://audioxxx.googlepages.com/EQ_169_STD_frq_selection_lo_filter.pdf

High shelving filter +/- 15dB. Default frequency is 20 kHz as in the original circuit,
but you can select a new value for C4 and C5 from this graph to change it:
http://audioxxx.googlepages.com/EQ_169_STD_frq_selection_hi_filter.pdf

Can someone explain the chosen frequencies for me?
I almost never use these values myself.
Is it creating some sort of wanted slope?
Are there any response curves pictures?

 

[G-Sun]

Is it something along these lines:

 

[jasonallenh]

Low shelving filter +/- 15dB. Default frequency is 20 Hz as in the original circuit,
but you can select a new value for C6 from this graph to change it:
http://audioxxx.googlepages.com/EQ_169_STD_frq_selection_lo_filter.pdf

High shelving filter +/- 15dB. Default frequency is 20 kHz as in the original circuit,
but you can select a new value for C4 and C5 from this graph to change it:
http://audioxxx.googlepages.com/EQ_169_STD_frq_selection_hi_filter.pdf

Can someone explain the chosen frequencies for me?
I almost never use these values myself.
Is it creating some sort of wanted slope?
Are there any response curves pictures?

These charts allow you to choose your own frequency for the high and low shelving filters. If you don't like the default/original frequencies, you can select a capacitor value from the chart that corresponds with the frequency you DO want.

Is it something along these lines:

Not quite- Your picture has Hi-pass/low pass filters. These are not the same as shelves.

 

[G-Sun]

These charts allow you to choose your own frequency for the high and low shelving filters. If you don't like the default/original frequencies, you can select a capacitor value from the chart that corresponds with the frequency you DO want.

Thanks! I've seen that. but I need to understand how the original design works first.

Not quite- Your picture has Hi-pass/low pass filters. These are not the same as shelves.

No, that's shelves I've used in my pictures.

 

[dmp]

I swept mine a few years back  -  see page 9. 

They affect frequencies more into the audio range than the 20 Hz / 20kHz would lead you to believe.

 

[G-Sun]

And the high / low frequencies boosted (with the stock capacitor values)

Thanks!
This is exactly what I was looking for
Now I understand much better.

 

[Siegfried Meier]

Hey guys,

R1 and C1 are shown as empty in the original docs.  Is this true?  Or am I missing a part here...I've left them out, I have no sound when engaged.

Thanks!
Sig