Jump to content
buji

Easy Notch filter and Phase invert for HX stomp?

Recommended Posts

One of the pedals I'm hoping to replace with my new stomp is an LR baggs venue DI, which I've had to use to date as an anti-feedback for my mic'd banjo (in a punk band). The beauty of the lr baggs is the easy notch filter knobs and phase invert that allow me to quickly adjust to a new venue / bar / barn / wherever we are playing. FYI the banjo needs 2 notch filters because the strings resonate at one frequency and the body / drumhead another. 

I'm pretty solid on the concept of how both of those functions work on the lr baggs, and I'm thinking there's got to be a way to accomplish at least the notch filters, but before I start reinventing the wheel, I thought I'd post and see if anyone else has already done this (or similar) I did do some googling and searching on this forum so either I'm not using the correct terms or this might be a rarer request than I thought.

 

Any Advice?

 

 

Share this post


Link to post
Share on other sites

A notch filter is just a parametric with a tight Q.... the Stomp has the perfect tool for you... a parametric EQ.

 

The parametric EQ has 3 bands (essentially 3 notch filters) plus a high and low roll off. 

  • Each band has a specific range of frequencies... but you should be able to find 2 that overlap enough to cover your needs.
  • The Q control is critical... you will want to keep this "tight". The higher the value, the tighter the Q. By default the EQ will load with a fairly wide Q for tone shaping, but for a notch filter I would start around the half way point... then adjust as needed, probably increasing the value even more.
  • I find with Banjo (I dabble with 5 string) I also like to utilize the low cut... and raise that to about 400hz. This stops my banjo from shaking violently as the tech turns up the volume :) YMMV depending on the tone you are after. I don't need rich low end, you might!

 

As for the phase invert.... there isn't a direct switch for it, but when using a parallel path the merge block allows you to flip the "b" polarity.I don't know how the LR Baggs implements it... but if it's just a phase reversal on the output (common) you could try this...

  • In your chain, drop one effect to the B path
  • In the split block, change it from a Y to a Split A/B and route ONLY to the B side
  • In the merge block
    • Set your A level to it's lowest setting possible. this is just a precaution to make sure no signal is bypassing the B path
    • Now you can invert your entire signal by changing the "B Polarity" as required. 
  • Like 2
  • Upvote 1

Share this post


Link to post
Share on other sites

Thank you SO MUCH for taking the time to respond! 

 

You're absolutely right, that low end at just under ~400hz is where the body seems to resonate on my 6 string . I have to 140hz sized notch filters set at ~300 hz and another one at ~1200hz (for the strings) so presumably I have a 'hole' from ~230hz-~370hz, and another one from ~1130hz-~1270hz. This does give me pretty good plunkity action on my D string (Banjo is tuned EADGBE, with top E and A using light strings to a make a 'roll' with the double high 'E's I sound like a much faster banjo player than I am). We have a couple of metal songs that rely on that low D string for enhancing the bassline so I'll need to be mindful of that. I have a POS old Roland Amp that is suuuuper feedback-y so I'll be testing with that. 

 

So to set the Q size, is that the "Low Q" value? I presume LoFreq is where the control point is on the eq, and LoGain is how much off of 0db center that control point should be? 

 

I had been experimenting with the 10 band eq to do this same kind of thing, but if I can cut a strategic 'notch' with the parametric, all the better. I can always overall tone shape at a later block with a trad EQ or do it at the board (but I don't wanna). On the banjo, I don't need a bunch of blocks :D.

 

I'm going to have to carefully read your instructions for th phase invert while I'm setting it up. I only briefly experimented with a and b paths when learning how to create a preset. AFAIK, the LRBAGGS phase invert is just a straight up wave invert on the signal output, so it's mostly for dealing with feedback from the monitors, and the phase changes every 4.8 feet or so away from the monitor (and is also based on if the monitor is running true polarity or not... some venues...) 

 

Share this post


Link to post
Share on other sites
2 hours ago, buji said:

So to set the Q size, is that the "Low Q" value?

 

Each frequency range has it's own Q value. EG: The low Q Value only effects the LOW frequency range, etc...

 

2 hours ago, buji said:

I had been experimenting with the 10 band eq to do this same kind of thing, but if I can cut a strategic 'notch' with the parametric, all the better.

 

A 10 band is good for tone shaping, but not for the precision of notching. The parametric will be your better choice for that. As you also say... you can use both. First notch (to correct/control) then shape the tone. 

 

2 hours ago, buji said:

AFAIK, the LRBAGGS phase invert is just a straight up wave invert on the signal output, so it's mostly for dealing with feedback from the monitors, and the phase changes every 4.8 feet or so away from the monitor (and is also based on if the monitor is running true polarity or not... some venues...) 

 

That is my assumption as well... If that is the case, then my steps should work fine. 

 

I hope it all works out for you. 

 

  • Upvote 1

Share this post


Link to post
Share on other sites

Good news and bad news.GN: The parametric did the trick for static feedback cancellation, just as we surmised. (at least at rehearsal last night going through the mains w/ no floor monitor)

Bad News, triggering the split with a footstomp eludes me. 

 

so... I must be doing the split wrong, or don't understand how splits are supposed to work.

I set up my para, cab, and light reverb effect on a path a to start. got it all set up the way I wanted it to sound. then I duplicated the blocks on path B. (because I want the same sound, only inverted when I trigger the B path) and assigned the split to fs1.

I didn't hear any difference (nor would I expect to) when triggering the fs1, so I said 'duh' and went to the variables for the cab and amped it way up and messed it all up, on path A, so I could hear a difference. To my surprise it just stayed on B path no matter what I did. 

 

So then I went to a built in preset that had a path A and B and sacrificed fs1 for that preset to the split, set the split to B100, and the merge to have 0%A path and tried again. Again stuck on just the B path. So I'm not understanding how splits work?

 

Tonight will be the first live show with the stomp instead of my old parametric DI, fingers crossed I don't have to worry about monitor-based feedback tonight. I'll just have to stay away from lead vocal's floor monitor... I think the rest of us are using IEMs tonight anyway. 

Share this post


Link to post
Share on other sites

Sorry for the confusion... I was just suggesting that you create a single path that actually uses both paths... 

You don't put anything on a footswitch... you just adjust the "phase invert" on the MERGE block when needed. 

 

Try my instructions again, without trying to invoke any switching. other than what you might have as effects normally. 

Share this post


Link to post
Share on other sites

I figured it out, I think, at least what I need for my specific use case. The A and B path and switching thing still confuses me but I'll read more and learn more. 

 

What I ended up doing: all block on B path, Split A/B, B100, and the merge 0% A path, and I was able to map the polarity variable to a FS with HX edit. Since I'm not messing with a bunch of effects for banjo, this worked great. Maybe there's a more economical way to do it without a split and B path, but I'm good (for now). 

 

Then I discovered that the FS's are capacitive and you can assign multiple triggers to ach FS, and cycle through them by touching, but it has to be touched by something else capacitive. How do you cycle FS modes without using bare feet or bending over to touch them? I'm off to find out. 

  • Like 1

Share this post


Link to post
Share on other sites
6 hours ago, buji said:

I figured it out, I think, at least what I need for my specific use case. The A and B path and switching thing still confuses me but I'll read more and learn more. 

 

What I ended up doing: all block on B path, Split A/B, B100, and the merge 0% A path, and I was able to map the polarity variable to a FS with HX edit. Since I'm not messing with a bunch of effects for banjo, this worked great. Maybe there's a more economical way to do it without a split and B path, but I'm good (for now). 

 

Then I discovered that the FS's are capacitive and you can assign multiple triggers to ach FS, and cycle through them by touching, but it has to be touched by something else capacitive. How do you cycle FS modes without using bare feet or bending over to touch them? I'm off to find out. 

 

In global settings you can set them to be push button instead of capacitive.

Share this post


Link to post
Share on other sites

 

12 hours ago, buji said:

What I ended up doing: all block on B path, Split A/B, B100, and the merge 0% A path, and I was able to map the polarity variable to a FS with HX edit. Since I'm not messing with a bunch of effects for banjo, this worked great. Maybe there's a more economical way to do it without a split and B path, but I'm good (for now). 

 

It really doesn't matter if you put one effect down there, or all effects down there. The only point of using that lower path in this scenario was to gain access to the phase inverter on the merge block. Sounds like you got that sorted out.

 

Share this post


Link to post
Share on other sites

Create an account or sign in to comment

You need to be a member in order to leave a comment

Create an account

Sign up for a new account in our community. It's easy!

Register a new account

Sign in

Already have an account? Sign in here.

Sign In Now

×