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Im building the screamer kit, it will be used as a boost for my Yba-1.
This will be used for rythm and lead, could somebody explain to me the differences between the two?

Symmetrical clipping clips off the same amount from the positive and negative portions of the signal. In asymmetrical clipping one half of the signal gets clipped a little more than the other. A lot of people say that asymmetrical clipping sounds more "tube like". Here's my take on that. I think symmetrical clipping simulates an amp that has matched output tubes and asymmetrical clipping simulates an amp with un-matched output tubes.

would a-symetrical have more "bite"?

It has slightly more compression. Whether or not that translates to more "bite" or not I don't know. I'm terrible at trying to describe sound with words so I'm not really sure what bite means sound wise.

To me assymetrical clipping isn't quite as dirty. It's quite a bit clearer to my ears. It also doesn't have a much output either, as there's an extra diode or two in the clipping stage taking some of the signal down. It really works for me on the out of phase positions on my Strat by keeping my tone a lot snappier and less mirky. You could always put two pieces of socket strip where the extra diode can go. This way you can experiment by putting a jumper in the two sockets, and then put an extra diode in the jumpers place so you can do a comparison and decide if you like your clipping symm or assymm.

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Keep 'yer tips tinned, 'yer sponges wet, and TELL THEM KIDS TO SHUT THE HELL UP!!!

That's really odd. My impressions are the exact opposite. I've built pedals that use two 1N914 clippers and a DPDT toggle switch to remove one of them and replace it with a 3mm red LED. When I actuate the switch I hear a jump in output and more distortion.

I could have my shit backwards, which wouldn't be unusual for me - LOL. I did mine with two 4001 diodes in series for my asymm clipping. When the switch is in the symm clipping mode, it's just two N914's.

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Keep 'yer tips tinned, 'yer sponges wet, and TELL THEM KIDS TO SHUT THE HELL UP!!!

You crack me up!!

When in doubt... add a switch and have both!!

I did one 1n914 diode and two IN4001, and the stock cap values and the jrc chip.
This.. Sounds... AMAZING.

oh. and i got it first try

Glad you like it, and congrats on getting it first try. I hope I'm able to do the same, the Screamer will be my first build.

Geekmacdaddy and someone else had a couple alternative IC suggestions for the screamer as well, as far as mods go:

Try RC4559 and TLC2272ACP chips for screamers

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µ

IMO, asymmetrical clipping sounds cleaner as well. And less compressed. This is only noticeable to my ears with at least 2 or more 1N4001 or LEDs in series, parallel to a single fast switching diode like a 1N914, 1N4148, or Ge diode. I can't hear any difference unless there are several diodes in series on one side.

Seems we can't agree on the effects of clipping mods, Stephen. I still maintain that the faster the switching diode, the more distortion you will hear. I think this is why I hear less distortion with the asymmetrical clipping when using two 1N4001 in series - the 1N4001 don't clip as fast.

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*patience is a virtue*

Please do not PM me. email is prefered. keith@buildyourownclone.com

I don't see how it could possibly sound cleaner and less compressed when you are in fact squashing the signal even more by clipping it harder. It's just like comparing a Vintage RAT with it's 1N914 clippers to a Turbo RAT with it's LED clippers. To my ears a Turbo RAT has more distortion than the Vintage RAT because it compresses the signal more by clipping the signal harder than the 1N914's. If you were to look at a 1kHz sine wave on an O-scope that was clipped by a pair of 1N914's and a sine wave clipped by a pair of LED's the output of the LED clipped signal would look almost like a square wave compared to the 1N914 signal due to the harder clipping. Now I realize these pedals use symmetrical clipping but the same principles still apply to asymmetrical clipping. If you're clipping one half of the signal harder than the other you are compressing or squishing it more on one side than the other.

This diagram is a good example of how soft clipping compares to hard clipping. The hard clpped signal gets compressed more because it has more of the signal's tips cut off.


Hope that makes sense.

wow. we could go back and forth on this forever. in building numerous breadboard versions of just about every practical circuit out there, i can say from my experience that the type of diodes one uses has much more to do with subtle differences in sy/asym.

for example, a pair os silicon diodes will always sound sharper, more focused, almost razor-like in some applications, while germaniums will have more compression, less overall output, but more character, more swirl, and a bit less ultra-high end. combining typs and numbers of diodes will only make the possibilities endless.

on the byoc 250+ i just built, i used an asym silicon/diode pair and recommend it highly. as with just about every matter of componant selection though , your ears are the only true judge.

that is why i highly recommend dropping $25 on even an average breadboard and a set of jumpers at radio snack. you will not regret it and your skills wil lincrease tenfold. and for me, thats alot.

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in fuzz we trust!

Like I said earlier, It couldn't hurt to put a couple pieces of socket strip where the diodes go either. It would allow you to experiment with out having to desolder any of the diodes. I'm definetly going to be putting sockets where the clipping diodes go in the Distortion+ clone I'm going to be building.

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Keep 'yer tips tinned, 'yer sponges wet, and TELL THEM KIDS TO SHUT THE HELL UP!!!

That is backwards.

LEDs have a higher turn-on voltage...usualy >1v. So they clip the signal less, and have higher output.

Silicon diodes like the 1N914s or 1N400x turn-on at about .6v So they clip harder and get compressed faster which also means a lower output volume.

Using two SI diodes in symetrical clipping will get very compressed and just sounds stuffy and flat to me.

I LOVE using one LED and one Si diode in asym. it keeps things open yet smooth.

Three Si diodes in asym will probably sound very similar to one si and an LED, because the sum of the turn-on voltages are about the same.

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just a po' college kid.

N.O.C.3 Effects!

yeahyeah, that post made you sound very smart.

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safe? who said anything about safe? of course He isn't safe! but He's good. He's the king i tell you!

Yes. That makes perfect sense. But what an oscilliscope shows, and what the human ear perceives is often two different things. Also, compression is relative based on amplitude. That graph is only representitive of a perfectly even signal. It doesn't take attack and decay into cosideration. I think if your graph were to show my "theory" under realistic conditions, it would show a greater relative difference between the peaks and valleys for the hard clipping, and a higher frequency for the softer clipping.

But this is just my theory based on what differences I can hear between the vintage rat and the turbo rat or the 250 and dist+.

_________________
*patience is a virtue*

Please do not PM me. email is prefered. keith@buildyourownclone.com

Yeah yeah is right, you have it backwards Stephen. You're not squashing it harder by using higher voltage clipping, you are actually opening it up.

In a distortion circuit like the 250+ or the Rat, the higher breakover voltages of a LED or the series side of an asymmetrical stack allow more output and a less compressed sound. The Turbo Rat is much less compressed, has more output, and is "cleaner" (especially at lower gain settings) than the Vintage Rat. The VR will almost turn into a fuzz at higher gain settings where the TR will still be more of a distortion. Yes, the LEDs may clip a little "harder" and "edgier" when they turn on (not very much though, compared to a silicon diode), but they still are more open and allow more output. What I think you are missing is that the maximum output voltage is set by the breakover voltage of the diode, so, a LED with a ~1.2V breakover will allow more output than a 1N914 with a breakover at ~0.6V or so, in fact the output will be close to double, which roughly translates into 3dB or so.

In an OD circuit (like the original poster was asking about) where the clipping is in the feedback loop, things change. You most likely will get a little more compression and a warmer sound from asymmetrical clipping because the clipped waveform is now being subtractive on the original waveform as it goes through the opamp, so higher clipping voltages probably produce more clipping in a OD circuit vs less in a distortoin circuit.

To answer the original question, you need to experiment and use your ears to see what sounds best to you. In either case, distortion or OD, asymmetrical clipping generates more even order harmonics which are more tube-like than the edgier sounding odd order harmonics. It will also add a slight octave effect because of this, you probably won't notice it, it is very subtle. I like my Boss SD-1 because it is asymmetrical, but both have their +s and -s, TS's are fine sounding pedals too. I also like my Mighty Mouse in Vintage mode because that is the real "Rat" sound to me.

Ahh, humble pie. The taste is bitter.

I did some research and I do have it backwards. What could I have been thinking?:? However I'm still not hearing it as cleaner. Maybe it's the jump in signal level that's making me hear it as being dirtier. Could the signal hitting the front end of my amp a little harder be making the difference? That's my guess.

Ah, it's not so bad when you step up and take a bite, it's when you put it off that makes it worse. Trust me I've eaten my fair share and more But, learning something new is always (well, almost always) worth it.

Yes, it could be hitting your amp harder, quite a bit harder in fact, that makes it sound dirtier. What kind of amp are you using? If you set your amp for a really clean sound, then try the vintage and turbo modes, the differences should be very clear.

Later,
Roger

I built both amps myself. One is based on the AX84 SEL High Octane (20W single ended) and the other is an 18W Lite II from the Silvatone web site. I tend to use the HO the most. I'm not real happy with the Lite II. I can't seem to get the volume control to work the way it should. I've used several different volume controls (using 500K & 1M pots) and tone stacks (the Silvatone, Moonlight and a modified 5E3 from the 18W web site) and no matter what I do I can't get a nice smooth increase in volume as I turn it up like I get with the HO. The Lite is just cracked open (Off to about 8:00) or full on. There is no increase in volume once I reach about 12:00. There might be a tad more compression but no noticeable increase in volume level.

Sounds cool, I haven't built any amps from scratch, I've modded a few old Marshalls though (and restored a few too). I've thought about building a 1987 clone and putting in a PPIMV, but I really like my Trace Elliot SpeedTwin. It has alot of SS sprinkled in the circuit but still gets it's gain from tubes (no diodes). There's something about a simple single channel tube amp that floats my boat though. Especially since I'm diggin' my Mighty Mouse so much. I usually practice with it through a Crate Powerblock set almost clean. I'd have to sell my Trace to finance building an amp, so I"m kinda hesitant to do that.