ddmilne

Using a parametric EQ with a very narrow Q will prevent you from cutting out frequencies that you don't wish to attenuate. You'll never isolate one pure fundamental frequency, but using as narrow a peak as possible will minimize that effect. 

If you set the Q first, then boost the output, you can scroll through the frequencies to isolate the spot that's most objectionable, then roll the output back down, and that should give you a fairly narrow cut. 

Did you try playing with the input impedance? 

Most of the time I use a Gibson LES PAul Classic. What I am finding now is that if I use AMP +CAB on more than a few modules the clean tones are good and full until you add any OD or distortion from the helix. It woul be great if they had in the editor a way to trap out specific frequencies because the objectionable sound I would like to remove is reasonably consistent and tends to be bright. If you try to use any EQ you end up eliminating wanted freqeuncies along with the one you want to eliminate

Tried input impedance , but it made matters worse.

You mentioned above using an IR  in your signal chain... if its a third party IR you can apply EQ, but you're stuck with whatever mic they used. Using  the stock cabs, you have a choice of  mic models, and distance. Some mic models (especially the ribbon mics) apply a much darker color to your sound, and may help eliminate some of the harshness you're hearing.

Actually I don't know if there are "hundreds" in the same camp as you.  I'm certainly active not only in this forum, but the modeling forum on TGP as well as the Helix Facebook group.  And there certainly is a camp, and always has been from day one, of users that prefer to use the Helix with traditional tube amps and cabinets, and have been doing so since day one of the Helix as well as on the POD HD series.  There are clearly some that don't get what they expect from the system in most part because they don't follow the general methods and advice of people that have similar setup to theirs.

Clearly the VAST majority of Helix users are using full range speakers and have been highly successful and satisfied with the investment both in studio and live applications.  The same is true of users with more conventional setups but with some understandable limitations on what features apply and how they would need to be used.  None of this is mysterious and all makes sense if you understand what the technology is doing and how it's meant to be applied.  But after several years of working with this stuff I've only come across a handful of people that simply couldn't achieve what they wanted to.  No one can answer why that is other than the person using it.  But given the success rate of the Helix among the folks that have bought it there's clearly no inadequacies in the fundamental design and implementation of the system.  I and the thousands of others using the system don't use it because of it's interface alone.  We gig with it weekly and have for several years now in venues as large or as small as you can imagine with great sounds and results.  Otherwise the Helix could never have been as successful as it has been in the marketplace.

I can assure you I'm no novice and I clearly understand what makes for great sound and great performances.  I've been doing it on stage and in the studio for more than 5  decades across the United States, Europe, and Asia.  So I'm not being fooled by a slick interface or nice looking design.  If it doesn't work for you then there's no fault in going to what does work for you.  But I can guarantee you along with tens of thousands of happy customers that there's no deficiency in what the Helix provides given what it is, and what it does...which is a modeling device.  That's it's core audience and it's core application.  And it does it as well as any others in it's category, and I've owned them all at one point or another.

Listen, I am sure that there are tons of satisfied customers, and i would surely like to be one of them. The majority of the users that I have come to understand that are very happy are those who are deeply intrenched in Music approaching Metal.  I have to cover a wide range of genres. The possibility of having a device to store and cover that range of tones is very appealing. But what I and the musicians in my area have experienced is that LINE6 Overdrive and Distortion Effects are rather shrill at stage levels in small to medium Venues. The Larger the room , the less offensive it becomes. There is also a astrong agressive attack that is picked up from pick action. We might all very well be doing something truly wrong, and I have taken steps this past few days to determine if I have and where i have. The Experts at Long and Mcquade have the Helix I used and have heard what I am talking about and under the same conditions I have tried to use the board. They agree that it isnt suitable for a live show given the P.A and Monitor we are using. What they are doing is looking at the Helix set-up to detemine if and where I (and many others in my area) went wrong. My frustration hasd a lot to do with the fact that this was on loan to me to make sure that it worked, and i spent days spinning my wheels and Line6 wasnt getting back to me. Many of you felt that I wasnt taking your advice, and that simply was not the case. Others directed me to youtube Line6 experts who replied in kind that they do not use the OD and Distortion Effects for the reasons I had stated. In once instance It was recommended that I use an AX8 as the favored live rig. Anyways, Yes, The Helix is a well developed interface and I do believe that as a recording tool you couldnt do much better. You say that you use the Helix live. How often are you encorporating the Overdrive / Distortion effects with amp models, and how do you find the output with rhythm at low mid and high gain overdrive settings using OD/DIST effects? Can you achieve the transparency of a real TS808 or Tube Driver and the like? If you can, I would like to know the secret. Again, my frustration turned into panic and that came out in my correpsondence with all of you. For that, I appologize. I am hoping that Long and Mcquade can deliver an understanding to me so I can get to use the Helix. I think I may have said this before, But I also had a Headrush and it too has issues with OD/Distortion effects and the IRs are terrible. At some point I am sure I will get over the hurdle.  But I cant put down 2000.00 without some degree of confidence that I will continue to use it for years to come.  I am sure that there are a lot of things to avoid in seteting up the Helix as a live rig. It would have been a great advantage to have had Line6 to publish this and save a lot of time for its customers. But, it is what it is. I certainly have no wish to get anyones back up in further discussions. It doesnt take much internet and forum research to see that a lot of users share the same reaction to the HELIX. Just as there are more than a few thousand satisfied customers. If I had the information I am looking ofr I would write and sell a book on the Helix and make some money.

I cover a very wide range as well including rock, jazz, blues, funk, acoustic ballads, and country and have never experienced the issues you're referring to as far as combining any of the Helix distortion pedals to any of the amp models.  I commonly use the TS808 (Scream 808), Klon Centaur (Minotaur), Teemah, and ProCo Rat on various patches with no problem.  Generally speaking I don't use the pedals for rhythm parts and depend more on the amp for that type of overdrive.  I do use the pedals for leads patches that I use the amp's natural gain for overdrive with no issues at all.  I do have one specific patch which is based on a Joe Walsh tone in which I use a HiWatt amp with a Teemah distortion pedal for rhythm work and add a Tube Screamer for the lead.  Again no problems at all with that patch which I've used consistently in various venues over the last year or so.

In that case I have the HiWatt configured with Drive=3.8, Bass=4.0, Mid=6.0, Treble=5.5, Presence =3.8, Ch Vol=9.1, Master=6.0, and deep parameters are all stock with the exception of Bias which is set to 7.0.  This is the amp only with no stock cabinet.  For this patch I use my Les Paul Standard with Burstbucker II pro pickups.  The patch doesn't use a noise gate and is set to Auto for Guitar In-Z.  I have a volume pedal as the first block of the signal chain.

I use a Celestion Redback 412 closed back IR mix of a MD421 and R121 mics with no hi cut or low cut

The Teemah is set to Gain=5.4, Bass Cut=2.9, Treble Cut=6.2, Clipping=Up, Level=4.0.

The TS808 for lead is set to: Gain of 5.2, Tone = 5.7, Level = 4.7

My final Parametric EQ has a high cut of 9.6 Khz, and no low cut and no other adjustments to any frequencies.

This is a dry patch with no reverb or delay.

I set my Helix master volume at about the 11 o'clock position which roughly measures at a -6db line level on the 1/4" out.  My XLR out is set to MIC level and is not affected by my helix master volume knob so it's sent at full strength based on the configuration of the patch levels.  This tends to be fairly consistent with the levels coming into the board from the other inputs including vocal mics.

On stage I'm using a Yamaha DXR12 attached to the L/Mono out on the Helix with the DXR12 volume level set at noon (unity), and I have no DSP contouring options turned on, and it's configured to not have any high pass sub-woofer filters engaged.  On stage the DXR12 is positioned behind me on a half-height speaker pole.

Our band's PA consists of a Mackie ProFX 22 mixer attached to two FOH towers each tower consisting of one QSC KW181 subwoofer with two KLA12 line array speakers.  I've also used this patch successfully on several other PA systems both line array and standard powered speakers, as well as in one venue in which we simply depend on stage volume for the instruments and don't go through the PA except for vocals primarily due to the fact that the PA is a passive system with a centralized power amp and isn't sufficient for dealing with the instruments accurately.

Hopefully that's enough information that you can compare it with what you're doing to see where the difference lies.

Here's a simple video we took of that song during a rehearsal to give you a feel for he sound.