So .......clipping ???

Dominic

I have pedals with Hi,mid Lo clipping options........things like Timmy etc
I can hear a difference on some (and volume drop) .....but it is very, very minimal difference in some cases
What is it, What's the point ,what should I be expecting to hear when diodes clip ?

Sporky

I did some Valvesporkers with a 6-way rotary switch that had different sets of clipping diodes. They did all sound a bit different - some were just dirtier or cleaner at a given gain pot setting, some were "raspy" where others were a bit smoother, but it wasn't a massive difference - definitely audible. They didn't change the base character of the pedal.

jonnygreentrees

Dominic said:

I have pedals with Hi,mid Lo clipping options........things like Timmy etc
I can hear a difference on some (and volume drop) .....but it is very, very minimal difference in some cases
What is it, What's the point ,what should I be expecting to hear when diodes clip ?

one setting on the Timmy takes the clipping diodes out all together I think. That's the setting I leave mine on

juansolo

Clipping is essentially waveform distortion. If you imagine a nice clean waveform as a smooth wobbly line, sticking clipping diodes in will limit that wave form causing distortion of the signal. The types of diode clippers determine how much signal effected, and how quickly it does so, so how square or smooth it is. Async clipping is when you use different values, numbers of or types on one side of the signal to the other. All of which creates different flavours of clipping distortion which sound different.

The timmy just adds more diodes depending on which position the switch is in, it’s not changing type (all silicon). Broadly speaking Ge clippers are smooth (in muff terms, we use these in the Ultrastoner to keep it nice and sludgy, but double them up so as not to lose too much vol), but you lose a lot of signal. LED clippers are much harder and let most through so seem louder (we use these in the TSM680 which are much harsher sounding). Si clippers are somewhere between the two (most muffs use these).

juansolo

jonnygreentrees said:

Dominic said:

I have pedals with Hi,mid Lo clipping options........things like Timmy etc
I can hear a difference on some (and volume drop) .....but it is very, very minimal difference in some cases
What is it, What's the point ,what should I be expecting to hear when diodes clip ?

one setting on the Timmy takes the clipping diodes out all together I think. That's the setting I leave mine on

There's always four in there (they're doubled up). Switch adds either one more in one direction (async) or two more, one in each direction.

Timmy Clippage

I would however love someone to explain the link to me that the Timmy has and what that does to the signal. It's pretty much unique in having that.

SmoothHoundUK

I would however love someone to explain the link to me that the Timmy has and what that does to the signal. It's pretty much unique in having that.

I'm going to stick my neck out here and reckon that link does ... not very much at all.

Matt_McG

I find the clipping diode options really obvious on some pedals, and also generally have a strong preference for one or other option. With a general preference -- but it's not always true -- for LED clipping over silicon or germanium, although as it happens, one of my favourites using silicon diodes.

ICBM

Very roughly, it’s like the difference between power valve types, which can influence the overdrive characteristics and headroom of an amp - although they’re actually only a minor factor in the overall sound of the amp.

Germanium diodes are like 6V6s - low headroom, soft clipping.

Silicon diodes are like 6L6s - medium headroom, medium clipping.

LEDs are like 6550s - high headroom, hard clipping.

But like power valve types they don’t change the basic sound of the circuit - that’s more determined by the topology and other component values, just like a Tweed Deluxe won’t sound like a Blackface Twin if you replace the 6V6s with 6L6s.

Sporky

SmoothHoundUK said:

I would however love someone to explain the link to me that the Timmy has and what that does to the signal. It's pretty much unique in having that.

I'm going to stick my neck out here and reckon that link does ... not very much at all.

I think you're right. I keep looking at it and trying to see how the link influences signal flow, but given that the flow is (more or less) unidirectional in each branch, linking the two doesn't seem to make a difference.

Wouldn't be terribly hard to mock up and test with a little SPST switch, of course.

ICBM

Sporky said:

SmoothHoundUK said:

I would however love someone to explain the link to me that the Timmy has and what that does to the signal. It's pretty much unique in having that.

I'm going to stick my neck out here and reckon that link does ... not very much at all.

I think you're right. I keep looking at it and trying to see how the link influences signal flow, but given that the flow is (more or less) unidirectional in each branch, linking the two doesn't seem to make a difference.

Wouldn't be terribly hard to mock up and test with a little SPST switch, of course.

In theory it makes no difference because if the diodes are all identical, there is always exactly the same voltage at the midpoint of each pair and hence no current flows in the link.

It's not like a 4-speaker cabinet where there is a difference between series-parallel and parallel-series - although the voltage division is likewise still the same, the link affects the damping factor because it alters the effective resistance each speaker sees from the other three.

juansolo

My thoughts also. I have tried with and without, and it made no discernible difference to me. It's just there on the original circuit...

Adam_MD

juansolo said:

My thoughts also. I have tried with and without, and it made no discernible difference to me. It's just there on the original circuit...

Me too I couldn’t tell any difference.  

Dave_Mc

That pic of the circuit isn't working for me, but I noticed very, very little difference between the switch settings on my timmy.

On some other pedals it's a lot more noticeable- e.g. the mooer rat clone, where it switches from si diodes to LEDs I think, and it affects the tone the way you'd think, as @juansolo and @ICBM described.

UnclePsychosis

juansolo said:

My thoughts also. I have tried with and without, and it made no discernible difference to me. It's just there on the original circuit...

-I've not looked at the circuit but could it be there just because it makes wiring it / getting suitable switches easier? 

juansolo

Dave_Mc said:

That pic of the circuit isn't working for me, but I noticed very, very little difference between the switch settings on my timmy.

Hopefully I've fixed that.

Danny1969

juansolo said:

jonnygreentrees said:

Dominic said:

I have pedals with Hi,mid Lo clipping options........things like Timmy etc
I can hear a difference on some (and volume drop) .....but it is very, very minimal difference in some cases
What is it, What's the point ,what should I be expecting to hear when diodes clip ?

one setting on the Timmy takes the clipping diodes out all together I think. That's the setting I leave mine on

There's always four in there (they're doubled up). Switch adds either one more in one direction (async) or two more, one in each direction.

http://juansolo.mooo.com/misc/stuff/timmy.jpg

I would however love someone to explain the link to me that the Timmy has and what that does to the signal. It's pretty much unique in having that.

I think it's this but it's early :

 The forward voltage drop of the diodes in series is doubled, conducting only on higher peak voltages ...  adding in the switch in one position gives symmetrical clipping at around 600mV moving the switch to the other position gives asymmetrical clipping of positive voltages of 600mV or so due to the single diode 

At peak voltages above around 1100mV the top set will conduct in addition to the single lower pair meaning more compression of the peaks .... switching to the single diode means the same but lower voltages are asymmetrical clipped like as OD1 

I could and probably am wrong

Adam_MD

.

juansolo

It's the link between the main 4 non-switched diodes that I''m on about. I've fixed the original post so it's clickable now to see.

Dave_Mc

juansolo said:

Dave_Mc said:

That pic of the circuit isn't working for me, but I noticed very, very little difference between the switch settings on my timmy.

Hopefully I've fixed that.

Thanks