Once again Mark Hammer has brought us something cool. Thanks
If you check out his RosyRay Circuit, there is a notch filter from an old fuzz that he uses. There is more about notch filters on the GEO (R.G.) site, I'll let them explain it. It has 2 resistors and 2 capacitors
Anyway, I stuck one after a Vulcan (between the output cap and the volume pot) and there it was, the really big chainsaw (the biggest Stihl, everyone should have one, but I have the smallest) sound that I like so much in the Sweet 16 (Doug Hammond) which has an adjustable notch filter
Anyway, it didn't quite suit me and it may behave differently with different output impedences.
First I changed the 10k resistor to 22k which lowered the bass output and lowered the notch in frequency and made it wider and deeper.
Next I changed the .001uf cap to .002uf. This made the highs stronger and lowered the notch in frequency some more, but reduced the depth and width.
Then I changed the .01uf (This is an edit, the scheme called for a .1uf cap, but my notes were incorrect) cap to .02uf which again lowered the notch frequency and broadened the notch.
So to recap, I have 2 - 22k resistors, a .002uf cap and a .02uf cap. I call it the 22 filter (makes me feel like I'm 22 - not). It may be too extreme for some, but experiment with the values. Lowering both caps in value raises the center frequency of the notch (which I lowered). Raising them lowers the frequency of the notch. Spreading the values of the caps farther apart increases the depth and width of the notch.
It's interesting how a notch filter makes the distortion sound more compressed. I think it is because many of the frequencies effecting dynamics are in the mid-range and reducing them removes dynamics making it sound more compressed.
I think Mark said the original could be switched in and out. It would be easy just to bypass it with a switch.
If I botched this explaination, someone tell me and I'll deleat it. The point is, there is an easy to use and adjust notch filter around for those of you with a need for notch. :twisted: :roll: 8)
QuoteThen I changed the .01uf cap to .02uf which again lowered the notch frequency and broadened the notch.
I was looking at the roseray, and i noticed there's no .01 cap, but a .1uF instead(the one that goes to ground). Is this the one you changed to .02? Or is this a typo and the final value was .2uF?
Thanks in advance.
Thanks for the nod, WGTP.
Its funny how people go to great lengths to get a bigger bottom and more bite, but somehow treat a notch filter as "just a notch filter". Maybe its the idea that something which takes away can't be as useful or "sexy" as something which boosts.
In any event, nice explanation and nice brainstorming.
Gringo,
Yes, I suspect it IS a typo, and that should be .2 instead of .02.
The thing to bear in mind about notch filters is that they provide two paths for the signal to "exit": one for highs and one for lows. The tonal outcome will be affected by:
a) what gets defined as "high" (in this instance it is defined by the .001uf cap that lets upper frequencies bypass the rest of the circuit, which WGTP changed to .002uf).
b) what gets defined as "low" (in this instance, set by the LPF action of the initial 22k resistor and .1uf cap to ground)
c) the relative spacing of "highs" and "lows" stemming from A and B above.
d) the relative amplitude of the high and low signals, partly determined by the second resistor that links up with the "exit" end of the bypass cap.
Increasing the bypass cap value brings more upper mids into the category of "highs". If the LPF cap to ground stays the same, this would actually reduce the width of the notch, but since the cap is doubled, the same way that the bypass one is, that more or less shifts the entire notch in a downward direction, with roughly the same width.
Increasing the second resistor adjusts the relative amplitude of highs and lows, giving a little more prominence to the mids/highs in the balance.
Note that this 4-component notch filter provides relatively shallow notching because neither path (high or low) is capable of more than single-pole (6db/octave) filtering action. In principle, the bass side could be made a little more complex to achieve a steeper filtering action.
At present, the 22k resistor and .1uf cap yield a LP response that starts rolling off highs around 72hz (meaning that 144hz would be 12db down). If that two-component combo is replaced with two cascaded sections of, say, 10k with a 47nf (.047) cap to ground, you'd have a 12db/octave slope starting around 338hz (284hz with .056uf caps), while preserving roughly the same high-to-low volume balance.
There is also no reason why the two LP filter sections have to be identical. Using different value caps in each section would yield different types of slopes.
In any event, the point is not to exhaust the permutations and combinations of notch-filter components. Rather, the idea is that it doesn't take much tweaking to achieve tonal presets which can deliver the sound you want in a dependable, and easy to replicate, manner.
Before we close this, take a look at the "tone" control for the Little Big Muff if you have a chance. It is essentially the same thing as the BMP tone control. Instead of a 100k tone pot which can be varied to provide different relative amounts of high-path and low-path signal, the LBM uses a fixed 100k resistor to replace it and a switch to select from one side or the other of the 100k resistor. In principle, this is like only being able to turn a BMP tone pot fully clockwise or counterclockwise, without any in-between positions available. This filter arrangement, in tandem with many of the suggestions presented in Jack Orman's "Presence Control" paper, provides another route for achieving sophisticated tonal settings in the form of easily switchable presets.
;oiklu
Whoops, you right. I had it written down in my notes as .01, but the scheme calls for a .1uf cap. That explains some things. Still, the values I used sound good. I'll have to try doing it correctly. Looks like I'm not getting a very deep notch. May be even cooler with the right values. 8)
You guys want to see a MASSIVE mid cut notch? Try a VOX tone circuit and using the Duncan Amp sim, start fooling with the resistors. MASSIVE notch but weird "interaction" with the knobs. Kind of cool - I have it as an option in one of my pedals.
Whoa! Tried the right part values, now that is a notch filter. It seems to start at the frequency extremes for a guitar and drop to the middle, I'm guessing around 1K.
How do you calculate the roll off frequency of the .001uf cap?
Tried the 22 some more and it isn't as extreme, more to my liking. I would SWAG it cuts around 9db at around 1.5k.
Also tried 047uf .0047uf caps and 22k and 4.7k resisitor version that sounds nice (makes me feel like I'm 47).
As Mark said, you can use this to cut the mids for more bass and highs Using a small 4.7 cap increases the bass output. If the highs bug you, put a cap to ground from the output to cut them from the top down.
I never have my output maxed anyway, (especially with Joe's circuits) so the fact that this reduces the overall output doesn't matter to me. 8)
Just a notch filter schematic?
I'm not the one to want to figure out options froma page, would rather build something with sockets and pots, and mess with it from there.
Maybe I'm little tired, but I've searched and couldn't find the RosyRay Circuit . Where can i get it ?
Erio
http://ampage.org/hammer/files/Roseyray.gif
http://hammer.ampage.org/
Here are the values I'm using with my Vulcan. It's not a huge notch, but it smooths things out, compensates for my mid-heavy PV SS amp and adds a nice thickness with presence. 8) The suggested pot/resistors values control the bass/treble balance which varies with the size of the caps used. Hopes this helps you get monster tone. :shock:
Recommended Notch Filter
1uf_____ .002uf/.0047______ 100k volume/output pot
I I
I I
22k 4.7k - 22k - 50k pot?
I I
I__.02uf/.047uf___I
I
I
G
Could you redraw that? I can't figure the "ascii drawing" out, and i'd like to try it with my vulcan/obsidian.
Thanks in advance!
http://www.geofex.com/
At the bottom of the page, Quick and Easy Parametric EQ's, at the bottom of the article. Bridged T is the one I'm using.
Whe I try to edit the drawing, it looks OK. wierd.
The reason why the ASCII looks bad is that HTML doesn't allow two or more consecutive spaces, unles you manually force them using something like " " (non breakable space). Perhaps checking the "Disable HTML in this post" may get through. :idea:
Hopefully this should show the ASCII in order:
<font face="courier new">
<p>1uf--+--.002uf/.0047--+--100k volume/output pot<br>
| |<br>
| |<br>
22k 4.7k-22k-50k pot?<br>
| |<br>
| |<br>
+-------+--------+<br>
|<br>
|<br>
.02uf/.047uf<br>
|<br>
|<br>
GND
</font>
:shock:
Quote from: WGThickPresenceHere are the values I'm using with my Vulcan. It's not a huge notch, but it smooths things out, compensates for my mid-heavy PV SS amp and adds a nice thickness with presence. 8) The suggested pot/resistors values control the bass/treble balance which varies with the size of the caps used. Hopes this helps you get monster tone. :shock:
Recommended Notch Filter
1uf_____ .002uf/.0047______ 100k volume/output pot
I I
I I
22k 4.7k - 22k - 50k pot?
I I
I__.02uf/.047uf___I
I
I
G
Sorry, :oops: this is what I meant:
1uf--+--.002uf/.0047--+--100k volume/output pot
| |
| |
22k 4.7k-22k-50k pot?
| |
| |
+-------+--------+
|
|
.02uf/.047uf
|
|
GND
I just wrapped it between "code" and "/code" keywords in brackets. This honors the spaces and uses a monospaced font.
This is the way to post ASCII graphics!
ahh!
tnx stm!
Yeah, that is what I meant. THANKS stm
I'm finding that the .022uf/.0047uf combo with a 10k resistor is my preference. That produces the smallest notch of the options listed (I'm SWAGing that it is -9db at 1.6k) with the .047uf/.0022uf combo producing the largest notch (SWAG -18db at 1.6k). 8)
Now I don't like the distortions without the notch :shock:
Happy filtering. :D
5 parts and a few connections..I gotta try this out.
I've been looking for a super simple notch to try...
That was easy. Sure does the nice job cleaning up the mids...takes 'em right out if you like. Interesting effect.
Makes getting the sheen on the highs real easy..I only tried it with a DS-1 I built so far, amazing nice job smoothing the crunch down.
I just stuck it in it's own box, last thing in the chain. Clean it sounds alot different too, but for Dist, it's a great thing to have one.
I used the DS-1, it has a tone knob, the Notch knob and the tone knobs interact very nicely.
Thanks for posting that little circuit, I didnt even have to copy it on paper, just did it by memory in about 15 minutes, socketting the 22k and .022uf, using a 47k trimpot [I think 20k would do it].
Using it to great effect, I'd been looking for a notch, this one does a neat trick, a great accessory to any Fuzzbox [I sezz], and no power supply...
Quote from: petemooreSure does the nice job cleaning up the mids...takes 'em right out if you like.
:shock:
Noooooo!
Just kidding :wink: - if you're going for the scooped mids thing, this is a great and easy way to get it for any effect. Not my cup of tea, but it does give you some added "crunch" and makes many distortions sound better - just lessens their ability to cut through in a band setting.
yupp, Thins it ... should be amp sensative and guitar too, what distortion your'e using and where the tone knob is set matter...
It seems to get pretty normal sounding [no bypass yet] if i turn the pot a little ways, then I can tune in what is a very noticable alteration at high setting.
Messing with Dist EQ is always interesting, can take your out of hand Fuzz sound and tailor fit it, often taking your favorite Fuzz and making just plain better if not just more variable.
I really am happy this mod popped up, I'd been stuff with opamps, this one seems guaranteed low noise, and offers many advantages [if less variable than] over the OA stuff I was working on.
It gives a shaping effect I didn't have, Offers a new voice to my Distortion [only tried the DS-1 so far], one of the simplest most useful builds I've done in a while...it fills the nitch :lol:
What a nice thing to have with your distortion, Clean too, I like recording various voices, having not tried it with bypass, or at high volumes, I can only guess or theorize...should tune to smooth sound that will cut through a stage mix, [I'll try that tomorrow probably].
Perhaps I add gain transistor on it after I try it with bypass, I'm thinking notch tone but louder would be nice switch to have for leads. :D
Very well said. I agree 100%.
I finally had time to read the GEOFEX article and I think this is called a Bridged T Filter. Using 2 - 22k resistors and a .01uf and .0047uf cap produce a notch at 1.6kHz. The equation for the center frequency is the same as a regular hi or low pass filter at 6db/oct. According to R.G., it is a fairly broad notch. Obviously when we start changing the ratios between the caps and resistors, the equation must be changed to be accurate. That is why I was SWAGing.
I found another nice combo last night a .01/.0047cap 22k resistors combo that I think notches around 2.4kHz It reduces and highs and smooths things out leaving a nice mid-range with some sparkle on top. Using it with a Joe Davidson "Frankenstein" of a mosfet Blackfire stage and 2 "Vulcanized" Obsidian stages. Very nice
Need to try this if your into distortions. Lots of variations. You can use a dual pot and vary the resistance values or switches to vary the cap values. 8)
What is "SWAGing'?
yupp a little tuning and I like it just fine with the one knob.
The sockets for the 22k and the .0022uf [?] seem to make it pretty tunable...more knobs/switches could of course be added, I find just a simple preset nothch to be quite usable...
It's like an 'instant 'ol friend' to me already.
SWAG = Scientific Wild A** Guess!
It is sort of strange the way it adds smoothness and compression even with the distortion maxed. Much more processed sound sounding. 8)
SWAG = Scientific Wild A** Guess!
It is sort of strange the way it adds smoothness and compression even with the distortion maxed. Much more processed sound sounding. 8)
http://www.jeverman.com/lff.html
Check this out. Someone is already doing this commercially. 8)