Have a read of this application note. What you want is called a "make before break" audio switch. They make some that are a direct replacement for the 4066. You will have to pick the one you need from this application list. http://www.maxim-ic.com/app-notes/index.mvp/id/638 No need to change anything or add anything in your circuit.

 

Have a read of this application note. What you want is called a "make before break" audio switch. They make some that are a direct replacement for the 4066.

The only 'noiseless' Maxim switches I've encountered to date are the 4910/11/12, which are not, of course, direct replacements for the 4066.
AFAIK, they're only available as surface mount?.....

I didn't realise they do a 'noiseless' audio DIL direct replacement for the 4066 as well....that's excellent news!

Do you have the part number?....

 

Thanks! I am going to try to find the right make before break CMOS ad give it a go. I am also going to try the NP capacitors as well because I am the curious type and want to try all options for myself.

 

The only 'noiseless' Maxim switches I've encountered to date are the 4910/11/12, which are not, of course, direct replacements for the 4066.
AFAIK, they're only available as surface mount?.....

I didn't realise they do a 'noiseless' audio DIL direct replacement for the 4066 as well....that's excellent news!

Do you have the part number?....

I am looking at Maxim pages but I am having trouble finding much in through hole design. I tried tech support but got nowhere. Any suggestions for through hole IC's?

 

Guess things are changing! This part MAX4542EPA http://www.maxim-ic.com/datasheet/index.mvp/id/1697 was available in a dip package and is still listed on the data sheet but a quick search says no one has them. But a SOT package isn't that hard to use.

Maybe on E-bay?

 

I have tried the Non Polar Electrolytic Capacitors with 2.2μf and 4.7μf, I even tried 1μf's and 10μf's, but they are all still producing a pop.

Rogs was correct that...
"At best this will allow 'pops' of different volume, every time you switch. At worst, it will introduce distortion into the signal path."

With the NP's I am now getting varied "pops" with the signal change.

I am really having a problem finding a good thru hole IC, there has to be a few good DIP's that fit the bill.

 

I don't think you are likely to find one - at least not a 4066 compatible one.....and I don't know of any other 'noiseless' ones.
Maybe someone else can come up with something?...

If you are still keen to switch your signal path, before the amplifier, take another look at Silonex opto coupled LDRs I linked to earlier. They will not introduce any distortion into your signal path, and you can make the switching silent.
You may need to experiemt a bit, to find the best way to effectively 'switch' your signal routing at such high impedance, by just using variable resistors, but that's what 'hobby' electronics is all about....

 

I don't really care if it is 4066 compatible chip as long as it can act in a similar way, i.e. SPDT style with two inputs each having it's own 2 outputs.

 

I just ran across a digital controlled analog switch with built in "break before make" & available in 14 pin through hole!

It's a TI CD74HC4016 and here is the link to the data sheet http://www.ti.com/lit/ds/schs199c/schs199c.pdf

Please take a peek and tell me if this might be the IC I need.

 

74HC4016 (and 74HC4066) are higher speed versions of the standard 4016 and 4066 switches, and are designed to work from a 5 V supply.
They are much faster in operation than the 4016 or 4066 (not important in your application).
They will still 'pop', I'm afraid.

Looking again at your original drawing, you also need to consider that you are presenting CMOS inputs 'raw' to the outside world.
CMOS devices are very sensitive to ESD (static) damage, and I suspect that they would not last very long in a 'real world' environment, without some sort of buffer protection against static discharge.

Look again at some of the commercial 'stompbox' schematics. You'll not find CMOS switching directly on the inputs and outputs on any of them.

If you want to make a silent, reliable, signal router, you need to think in a different direction.....

Direct (mechanical) routing (either through a multipole footswitch, or via a relay) or LDRs, are both worth looking at....

 

I don't mind going back to the beginning again because I want this circuit to perform flawlessly, transparently and with a simple design.

I do not want to go the mechanical route due to prior testing I have done with both multi pole stomp switches and mechanical relays. I found that they both can produce a pop under several conditions. I think I am going to jump into the FET switching concept like you referenced earlier.

I am also very interested in the optoisolator idea. I found a few that are actually not very expensive. Would this work for switching as well as the Audiohm series?

http://www.alliedelec.com/search/productdetail.aspx?SKU=70136794

 

Yes, that should work fine. If you're going to stick to using the variable resistor passively you may need to experiment a bit, as I suggested before.
After all these are resistors, not switches.

Don't use a configuration that presents any significant resistive load to your guitar output. Passive guitar outputs need to look into high impedance inputs, or you will affect the tonal response.

 

Tht's funny. Caps are there to block DC, and the pop is a DC signal decaying.

Is it not tht the pop is before the 4066 ?

 

Tht's funny. Caps are there to block DC, and the pop is a DC signal decaying.

Is it not tht the pop is before the 4066 ?

Have a quick read of the app note I linked to in post #5.

You cannot completely eliminate the pops from 4000 series CMOS gates. You cannot 'slow down' the gate transients.

You can make them 'smaller' or by ensuring there is no variable DC shift on input or output during switching - and capacitors can help achieve that.
They can also make them worse, if the DC charged states of the capacitors are allowed to vary.

 

If you switch quickly during a program then the instantaneous level is DC which causes a POP.
You need to mute fairly slowly, switch slowly (ramping the control signal) during silence then slowly unmute.

 

If you switch quickly during a program then the instantaneous level is DC which causes a POP.
You need to mute fairly slowly, switch slowly (ramping the control signal) during silence then slowly unmute.

Which is of course exactly the reason you have problems with CMOS 4066. You can't 'get at' the gates, to slow down the gate switching time....

 

Hello,

When you have equal DC potentials on both sides of the 4066 switch, the "pop" will be lower.

The resistors can be in the range from 10 to 100K.
There will be no DC jumps on the capacitors on both sides.

Bertus

 

here's another thought.....Something I had in mind for future project of some kind

I will be using hermetically sealed relays specially made for audio switching.
I have seen this and I think it is much better than any other switch

 

If you suddenly turn on or turn off a CD4066 with a fast pulse then some of the pulse capacitive-couples into the audio as a POP.
But if you slow down the rise and fall times of the pulse a little then nothing is coupled into the audio if the audio is muted during switching.

 

Hello,

When you have equal DC potentials on both sides of the 4066 switch, the "pop" will be lower.

The resistors can be in the range from 10 to 100K.
There will be no DC jumps on the capacitors on both sides.

Bertus

Thank you Bertus, I tried this with 10k resistors and your tip immediately killed the pop in the switch!

What would be the difference in the circuit in respect to going lower with the 10k's or going higher as in the 100k's? I have tried them both and cannot tell an audible difference in the sounds overall tone or volume.
I was thinking that changing the size of the resistors would have changed the tone some, but now I am thinking that outside of balancing the DC level that the resistors do not color the sound. Is that a correct assumption?