Aengus graphic EQ (thumbwheel) information sought--any leads?

[soapfoot]

I will have a look at the NKK switches... do you have a part number for them ?

MRK-112A looks like it might work nicely.

Here is a link to a datasheet: https://www.mouser.com/datasheet/2/295/MRlogicLevel-1663588.pdf

10-piece price is $12.43 on Mouser. 100-piece price is $10.66

 

[Walrus]

The MRK switch is break before make B-B-M.
I think it needs to be M-B-B.

The only small one I can find easily is this....
https://uk.rs-online.com/web/p/rotary-switches/2242294

 

[wlinart]

The MRK switch is break before make B-B-M.
I think it needs to be M-B-B.

The only small one I can find easily is this....
https://uk.rs-online.com/web/p/rotary-switches/2242294

Compatible with the MRK switches are the grayhill 56 series. For example: 56SDP30-01PAJS, and that one is MBB

 

[soapfoot]

The MRK switch is break before make B-B-M.
I think it needs to be M-B-B.

The only small one I can find easily is this....
https://uk.rs-online.com/web/p/rotary-switches/2242294

Ah, I see.

What would be the consequence of using a BBM switch in this application? Pops on switching?

 

[soapfoot]

56SDP30-01PAJS is $13.91 at the 25-piece price, and $12.10 at the 100-piece price.

Not too bad.

Around a ~$100 switch budget per channel doesn't seem like a total deal-breaker to me. Originals are so expensive and hard-to-find that even a several-hundred-dollar build isn't out of the question.

 

[Bobby Baird]

Ah, I see.

What would be the consequence of using a BBM switch in this application? Pops on switching?

Yes the amps will produce a small dc offset in mV causing a pop when switching. This can be reduced by using bipolar caps to resistor to ground to shunt the dc. A basic RC HPF typically 47uf & 10k resistor. MBB may cause band interaction for split second while switching. This can be simulated in LT spice with the dc analysis function.

 

[Bobby Baird]

I’ll take a stab at this circuit when I get some time. Love 560 on snare kick guitars and bass. I’ll Draw something up in kiCad when I finish another project. Sylvia Massey uses the Anegus on kick and bass I believe. Would be a good compliment of frequencies in series with the 560.

 

[Bobby Baird]

Bourns makes s-curve slider pot but they are special order.

 

[dmp]

Bourns makes s-curve slider pot but they are special order.

What value are you looking at using? The Aengus uses a sum of slightly over 2Meg
A different value would require other changes to the circuit I think.
Take a look at this project. I'm curious how close a 560b would sound simply modifying the CCRR in the gyrators for the frequency points.

 

[Bobby Baird]

Getting the q correct is the main thing changing values is not a big issue. I don’t buy into being a circuit purist. That balanced differential input Jensen output would work for me.

 

[Bobby Baird]

I’m out of town right now can’t look up data sheets. Right down the street from Mouser though.

 

[Bobby Baird]

I’ve built a couple G.TEN’s

 

[dmp]

Getting the q correct is the main thing changing values is not a big issue. I don’t buy into being a circuit purist. That balanced differential input Jensen output would work for me.

The Gyrator sets the q. The Aengus has a q=1.37 (very close to the 560b with q= ~1.4 to 1.5)

 

[pinebox]

The schematic is here;
http://www.audiomaintenance.com/downloads/ez404_Schematic.pdf
This was the PCB:
http://www.audiomaintenance.com/downloads/ez404_PCB.pdf
[The edge connector was only so that we could easily test it using our 500 series jig... just me being lazy].

This forum always surprises me with cool ****.

If you dig up a pair of those old boards I would be interested.

 

[Slenderchap]

This was the prototype that we made about 5 years ago (I think).

http://www.audiomaintenance.com/downloads/ez404_prototype.jpg
The top PCB used 741's and had no input transformer.. the lower PCB used some modern IC (not taking it to bits to find out what) and had an input transformer.

Worked fine I believe..... and sounded like the original... they are supposed to be excellent for electric guitar.

Colin.

 

[soapfoot]

I love them most on kick drum and sometimes bass (guitar or synth)

 

[Bo Deadly]

Output amp card schematic. Someone check my work, seems strange (edit, fixed a mistake)

Can't be right. There's nothing driving the output. And the 1K6 doesn't make sense. And there's no way you're going to get 66dB of gain out of a 741. It doesn't have the bandwidth.

 

[dmp]

Nope, it wasn't.

The schematic is here;
http://www.audiomaintenance.com/downloads/ez404_Schematic.pdf

 

[Walrus]

Can't be right. There's nothing driving the output. And the 1K6 doesn't make sense. And there's no way you're going to get 66dB of gain out of a 741. It doesn't have the bandwidth.

Sorry, that is my mistake, the resistor is actually 3K6 not 1K6.

 

[Walrus]

Nope, it wasn't.

Link works for me.