Double Bass Help: AI Coda or Clarus 2R plus a Wizzy?

[bolo]

40 Hz makes sense - fundamental pitch of the low E on the instrument (pretty much). Just cut anything below that - those pesky infrasonics. (I learned that from Doc.)

Some other chaps actually set the HPF a bit higher, I think around the 70 - 80 Hz region. I think they like to call it "dialing out the flab." Provides a little 'harder' sound perhaps. And some folks increase the high pass freq setting from as low as it goes on up as the overall volume goes up, if I understood their posts that is. I do know some cats absolutely swear by this high pass / low cut filter feature.

And then there are still others that use the notch filter instead of the HPF on the Series III combos and heads, w/ the freq set as low as it will go (30 Hz).

Like the manual says: "Experiment with the position of the control to give you the sound you like best."

Lots of features and knobs and tiny buttons. Picking up a Focus 2R head next week. Did I say that already?

 

[tornadobass]

Here's an interesting detail about the filters. I noticed that though the notch filter reverses phase to cancel feedback, the high pass does not reverse phase. This was confirmed by Rick at AI.

I only have a few gigs with my Clarus so far, but haven't used the filters at a gig yet. My previous rig for URB was a Fishman ProEQ into a WM12 and I usually used the phase reverse. This might be my most useful filter feature with the Clarus, too, although I've found (at home) that setting the high pass at about 11 o'clock tightens the sound by rolling off the lowest octave...as I read the manual there's still a slope rather than an absolute cutoff.

 

[drurb]

...as I read the manual there's still a slope rather than an absolute cutoff.

There's really no such thing at all as an absolute cutoff with these types of filters. That's what we call the "ideal" filter that is discussed in engineering texts. The slope is usually specified and should be at least 12 dB/octave for such use. By the way, my choice of 40 Hz has much to do with the typical resonant frequency of the ported speaker cabinets we typically employ. This has been discussed quite eloquently by fdeck in a number of his posts on the topic.

As for phase reversal, that's something you want to employ based on the room, the distance between the speaker and the bass, the phase of the signal coming from the pickup, the phase of the signal from the amp (which, by the way, will vary as a function of filter settings) and other factors. The idea is that one usually does not want the output of the speaker canceling the acoustic output of the bass itself.

 

[Bob Branstetter]

Oh, no! Do not forget about the filters. That is, the high-pass filter. Just search for my posts regarding the problems with infrasonics when using piezo pickups. Those unwanted frequencies can drive the AI and any other equipment bonkers by robbing power unnecessarily and producing abnormal speaker-cone excursions.

While the filters are a nice feature to have when you need them, my point was and still is that it is NOT just the filters that make the Series III better than the old Series I. I found my old Series I Contra had a tendency to get muddy when pushed to higher volumes. I have not had this problem with the Series III Coda without any filtering. I'm comparing Series I and Series III, not filter or no filter.

 

[Uncletoad]

Here's an interesting detail about the filters. I noticed that though the notch filter reverses phase to cancel feedback, the high pass does not reverse phase. This was confirmed by Rick at AI.

That confirms my experience with those filters. I thought something was up with the high pass. I have a hard time using it with higher volumes as the phase reversal is so crucial to high volume playing. I always went back to the notch set lower than the bass goes.

I still want a separate phase switch.

I prefer to have both phase and high pass control.

 

[flatback]

Ok can someone explain this clearly to me. I use both a mic (in channel 2) and a pick up in (channel 1) I thought that Rick had told me to have the HP past noon for the Pup and LESS THEN NOON for Ch2. That the phase was connected inversely to the HP filter. What I need is to be able to TURN IT UP jackson and still get the no muck sound I am used to at lower volumes. Sometimes (in some rooms ) It seems super nice...But I would sure like to know definitively how to set the dials for the mic blended set up at high volume(ish) in order to have the PHASE in opposition...Anybody?...Bob?

 

[Uncletoad]

Ok can someone explain this clearly to me. I use both a mic (in channel 2) and a pick up in (channel 1) I thought that Rick had told me to have the HP past noon for the Pup and LESS THEN NOON for Ch2. That the phase was connected inversely to the HP filter. What I need is to be able to TURN IT UP jackson and still get the no muck sound I am used to at lower volumes. Sometimes (in some rooms ) It seems super nice...But I would sure like to know definitively how to set the dials for the mic blended set up at high volume(ish) in order to have the PHASE in opposition...Anybody?...Bob?

Obviously some confusion here.

Perhaps someone would forward this to the fellows at AI and have them clarify. I know they peruse these forums from time to time and remain silent.

There has been much speculation about these questions and differing interpretations of the messages from AI.

My impression is that the Phase reverse is a byproduct of the notch filter. So using the notch filter on the channel you want reversed is the thing to do. No high pass filter would be available on that channel.

How I use it:

I use the notch filter on Chan 1 where my Full Circle lives and usually have the knob set to 30hz. I rarely change that regardless of the volume.

Low volumes the mic goes into channel 2 where I use no filters at all.

As the volumes go up to medium levels I leave the Chan1 full circle set the same and engage the high pass on the mic Chan 2. I set the frequency knob very low depending on the room and the mic sound. Like around 9 to noon.

At high volumes I stopped using the mic. It really doesn't do much at Rock levels but create feedback and squeals. The character of the bass is almost gone that loud and the string sound through the pickup carries the weight.

I could be wrong about that usage. I didn't design it. It works good though.

 

[bolo]

Obviously some confusion here.

Perhaps someone would forward this to the fellows at AI and have them clarify.

Done. I will make it a point to ask Rick in person too when I see him in a coupla days.

Bob K., you still there bro? This is way cool.

 

[flatback]

Obviously some confusion here.

Perhaps someone would forward this to the fellows at AI and have them clarify. I know they peruse these forums from time to time and remain silent.

There has been much speculation about these questions and differing interpretations of the messages from AI.

My impression is that the Phase reverse is a byproduct of the notch filter. So using the notch filter on the channel you want reversed is the thing to do. No high pass filter would be available on that channel.

How I use it:

I use the notch filter on Chan 1 where my Full Circle lives and usually have the knob set to 30hz. I rarely change that regardless of the volume.

Low volumes the mic goes into channel 2 where I use no filters at all.

As the volumes go up to medium levels I leave the Chan1 full circle set the same and engage the high pass on the mic Chan 2. I set the frequency knob very low depending on the room and the mic sound. Like around 9 to noon.

At high volumes I stopped using the mic. It really doesn't do much at Rock levels but create feedback and squeals. The character of the bass is almost gone that loud and the string sound through the pickup carries the weight.

I could be wrong about that usage. I didn't design it. It works good though.

thanks...It seems like you have it set exactly backwards of my vague memory of what Rick said
But backward in a polar world its just the other side of the coin...
I kinda had this idea that the HP was for the Pup...and I really like being able to dial out mud with it. The notch filter (from my understanding was to dial out howl from a mic...although I've never really used it as such. I futsed with it for a minute when I got the amp but the HP seemed to work more intuitively. But I do remember Rick saying that the HP all the way on on one channel and all the way off on the other reversed the polarity....
But I'm sure going to try Uncles method too.
I'll bet my Loud ain't anywhere close to your loud too. I just play jazz (sometimes with a loud drummer in a loud room...but never ROCK loud...)
...Can anyone figure out what I just said?

 

[drurb]

While the filters are a nice feature to have when you need them, my point was and still is that it is NOT just the filters that make the Series III better than the old Series I. I found my old Series I Contra had a tendency to get muddy when pushed to higher volumes. I have not had this problem with the Series III Coda without any filtering. I'm comparing Series I and Series III, not filter or no filter.

Agreed. My point was that one should not "forget" about those useful filters.

 

[bolo]

thanks...It seems like you have it set exactly backwards of my vague memory of what Rick said
But backward in a polar world its just the other side of the coin...
...Can anyone figure out what I just said?

To be honest, until tornado's post, I too thought the HPF engaged the 'undocumented' phase reversal feature, not the notch filter.

Well ... I will try to learn what I can from Rick and post it here by about mid-week.

 

[MT Spaces]

Bob K., you still there bro? This is way cool.

You betcha ! I'm still here lurking amongst the big kids trying to learn the ropes. This is indeed mondo cool . Heck, we even got Uncle T to quit dickin' with strings long enuff to get his top secret tips on using the 2-channel Series III stuff !

Bolo, I'll bet you can't wait to try out the Focus . I spent some time last night downloading the AI manuals to read up on the high pass filter settings and searching the archives for info on those pesky infrasonics. You, Dr. Upright, and all the others here carried on some great discussions. Not sure I understood it all but at least I know some of the lingo now.

I feel like I now know a fair amount about the Coda even though I don't have it yet and haven't ever played a DB through an amp.

Carry on Big Kids ...... I'm a sponge and I'm still listening. I'll wager a lot of other people are also learning something from the great info given freely by you esteemed TalkBassers. As soon as I get my photo taken, I will be donating to the site ....... I'm really starting to feel real guilty about sneaking off with all this invaluable information .

 

[flatback]

Here's an interesting detail about the filters. I noticed that though the notch filter reverses phase to cancel feedback, the high pass does not reverse phase. This was confirmed by Rick at AI.

ok this seems clear and like what I remember hearing before...But what I am confused about is this: If the notch filter reverses the polarity, is that polarity part of the sweep of the dial? Does turning all the way to the right undo the polarity reversal? Or is that in addition to some eq notch?

 

[tornadobass]

My understanding is that the notch filter is just wired that way throughout its whole range.

It'd be nice to have a separate phase switch like on the Fishman preamp.

 

[Uncletoad]

It seems like you have it set exactly backwards of my vague memory of what Rick said.

Wouldn't surprise me. I generally ignore instructions and do what works for me.

If the notch filter reverses the polarity, is that polarity part of the sweep of the dial? Does turning all the way to the right undo the polarity reversal? Or is that in addition to some eq notch?

Not quite. The polarity is changed as part of the function of the filter or perhaps more correctly as a method of providing the filter. So no matter where the knob is you are notching out some frequency. If the knob is all the way down you are killing notes that aren't really on the bass. In addition I'd imagine they have a super low set high pass filter on all the time to keep the amp from trying to do something it can't down in the 20hz and below dirt. So in effect is functions like a real low frequency high pass even though it's voiced as a notch.

To be honest, until tornado's post, I too thought the HPF engaged the 'undocumented' phase reversal feature, not the notch filter.

Well ... I will try to learn what I can from Rick and post it here by about mid-week

Yea. Do that.

 

[flatback]

Wouldn't surprise me. I generally ignore instructions and do what works for me.
Not quite. The polarity is changed as part of the function of the filter or perhaps more correctly as a method of providing the filter. So no matter where the knob is you are notching out some frequency. If the knob is all the way down you are killing notes that aren't really on the bass. In addition I'd imagine they have a super low set high pass filter on all the time to keep the amp from trying to do something it can't down in the 20hz and below dirt. So in effect is functions like a real low frequency high pass even though it's voiced as a notch.

Yea. Do that.

I'm copying your post and putting it on a post it and I'm gunna try your method of filtering. I just set up the filters with HP for the Pick up and Notch for the mic and that seems (in my studio) to sound good. Thanks so much for the clarification.

 

[Uncletoad]

I just set up the filters with HP for the Pick up and Notch for the mic and that seems (in my studio) to sound good.

That's backwards from what I do but the end result is very similar. If it works for you then that's perfect.

 

[MT Spaces]

That's backwards from what I do but the end result is very similar. If it works for you then that's perfect.

OK, now my pea brain is really confused . So the consensus on the proper use of the AI 2-channel Series III HP and notch filters for PUPs and mics is ..... (drum roll) ..... that there is no consensus . I guess it says a lot for a product that it seems to work no matter where the knobs and switches are!

Yea BOLO, I second and third the idea that you corner the AI folks when you see them (after, of course, you have the Focus in your hot little hands) and get some things clarified. Maybe you could talk them into doing a little technical writing (when they aren't busy building amps) and including a PDF file on their website.

While I am a rank rookie, it seems that all the pros here agree that HP filters, notch filters, phase reversal, etc. are cool things to have. So my vote would be to get some background on the use of these things and some practical application advice. While it is good advice when AI says "Experiment with the position of the control to give you the sound you like best," it would be helpful to at least have a clue about which tree to bark up .

I don't expect AI to write a PhD thesis on audio amplification electronics theory or divulge trade secrets that will get their designs knocked off but they could be somewhat more helpful. If nothing else, a PDF info page would cut down on the number of phone calls they have to field from all of us asking the same questions.

Let us know what you find out BOLO. Good luck with the Focus.

 

[MT Spaces]

So the consensus on the PROPER use of ...

I must be listening to the voices in my head too much ...... now I'm replying to my own posts . I just re-read my post from earlier in the day and realized that ....... Grasshopper, I have a lot to learn. "Proper" means whatever gets me down the road and makes the bass sound good for the room I'm in. Sorry guys, I'm an engineer during the day and I'm always looking for the "right answer." I'll follow the Uncle Toad and Flatback method and try different settings and see what happens. My Coda is supposed to be delivered Wed. afternoon.

Hey Tornado, thanks for giving us your take on the AI stuff.

BTW, that's some fine blues that your band plays. Jacqueline's voice is great. Why don't you come out west sometime? Our "big" blues fest is in Billings (http://www.magiccityblues.com/). Send a demo CD sometime (Link Removed.

It's usually pretty hot in Billings in August but at least the humidity ain't 400% like it is in Iowa . A few years back I saw Son Seals, Eddie Shaw and the Wolfgang, and John Mayall & Bluesbreakers. That was a fine Friday night out under the stars! We also have smaller fests in Hamilton and Kalispell, more in the mountains and more scenic than Billings. C'mon out.

 

[tornadobass]

Hey Tornado, thanks for giving us your take on the AI stuff.

BTW, that's some fine blues that your band plays. Jacqueline's voice is great. Why don't you come out west sometime? Our "big" blues fest is in Billings (http://www.magiccityblues.com/). Send a demo CD sometime (Link Removed.

Sounds fun...we're not much of a touring band...Des Moines is a road trip for us But thanks for the kind words.

I'll get a demo sent to the public radio folks. BTW, those songs on our MySpace site were recorded completely direct to digital. My bass went through an Avalon preamp. Guitar and harp through pedals, even electronic drums (although we gig with the real gear). My bass there is a G&L L-1000 with Chromes.