Question about unwanted exaggerated frequencies around 2.5K?

4406cuda

Inspired
I would like to determine the cause. I do not see many posts on this forum about it and I am wondering if it is how I configuring and connecting my AXE III.

I have the same issue with all my guitars with have passive medium output humbuckers. On all my guitars and on most of my presets there is this noticeable annoying frequency around 2.5K. It is "metallic plinky" sound. Also, it seems that I am constantly having to tame higher end frequencies without making the tone sound like there is a blanket on it.

I have tried different cables and I prefer Mogami cables. I also have tried different speakers and prefer Creambacks or the Lead 80.

I was initially using a Fryette Power Station and then the Fryette LXII before I got the Matrix.

I am running a 20' cable to a Analog Man buffer --> 20' cable snake (includes XLR for FC-6) to rear input 1 --> Output 2 --> Matrix GT1000 --> either a pair of 2x12 cabs or a pair of 1x12 cabs. My cabs have Creamback 65s or Alnico Creams

I play a variety of rock covers using Fenders and Marshalls, mostly. I use individual presets and scenes for each song that are created at band volume. All my presets are set to SS Amp with Cab. I have tried many impedance curves, but lately the 4x12 Greenbacks are sounding the best.

I usually start by limiting the input frequencies on the amp block from ~100Hz to ~6Khz. I occasionally use the 10 band output eq to lower the extreme low and highs. Occasionally, I have to turn off the bright switch for the Marshalls. I have played bright cap values. I occasionally run a ParaEQ after the amp block lower the 2.5K frequency -6db with a tight Q.

I use very little to a moderate amount of delay, very little reverb, compressor for cleans, and modulation when it is needed. I use my ears and the leveling tool.

A little about me: I have been playing guitar for about 45 years, both as a hobby and semi professionally. I am currently playing in two working cover bands. I currently own a Friedman BE 100 Deluxe, but would prefer to use the AXE III after it is dialed in. In the past I have owned an FX8 and AX8. I also have owned too many amps over the years.

Thank you Cliff and team for your great work and thank you in advance for anyone's suggestions.
 
That's one of the first frequency areas that I go to when my tone seems harsh, regardless of amp models, IR's, or even running into real cabs. I usually use the output eq's to tame it, as the amount of cut depends on the speakers I'm listening through and the volume I'm listening at. Too much cut can actually bury the guitar in a mix, but I know that frequency as soon as I hear it. Lately I've cut mine by about 3db lately, sometimes as much as 5db cut if my ears are particularly sensitive.
 
I've had this issue too. Might not be the same cause, but as soon as I saw your thread title I thought, "I wonder if it's a Creamback?". Then saw that you were using Creamback 65s or Alnico Creams.

Not to be that guy... but 2.5k is exaclty where there is a spike in the frequency response of all Creambacks. Go and have a look at the graphs - it doesn't even matter which type of creamback. G12H 75, G12M 65, Neo - they're all the same. Alnico Creams too. To be fair, many speakers have this, but it was a Creamback that was recently aggravating me.

Anyway, apart from saying "yes it's the speaker"... which isn't very helpful, I did find that I had the issue a bit more when using the Axe-Fx via an SS power-amp. It's probably because I hadn't selected the best speaker impedance curve (SIC). I ultimately managed to tame it a little by selecting a better SIC match.

I appreciate that you said that you've already tried all the impedance curves; but you could maybe take your best match and play with the HF resonance parameter. Perhaps you'll get closer to what you want that way.

Also (as of yesterday), the latest firmware beta includes some improvements to the speaker impedance curve modelling algorithm and some extra curves. Might be worth giving that a try too.
 
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Reading OP's post again, I'm wondering more about some of the details.

They said "I have tried many impedance curves, but lately the 4x12 Greenbacks are sounding the best". But they also said that they are using "either a pair of 2x12 cabs or a pair of 1x12 cabs" with their Matrix GT1000.

Whilst there are no hard and fast rules, surely a 4x12 speaker impedance curve wouldn't be a good match for either a 1x12 or a 2x12 cab?.
 
Reading OP's post again, I'm wondering more about some of the details.

They said "I have tried many impedance curves, but lately the 4x12 Greenbacks are sounding the best". But they also said that they are using "either a pair of 2x12 cabs or a pair of 1x12 cabs" with their Matrix GT1000.

Whilst there are no hard and fast rules, surely a 4x12 speaker impedance curve wouldn't be a good match for either a 1x12 or a 2x12 cab?.
The various impedance curves do not seem to be the best tool to tame the unwanted frequency. While I toggle through the various impedance curves, I am listening for which gets me closest to that warm and large tone I am hearing in my head when I dialing in a marshall crunch tone. I usually is a 4x12 greenback, basketweave, or TV

For cleans or EOB, it is usually a 2x12 or 4x10
 
@4406cuda Another thing I've rememberd: Do you have any speaker compression set in the amp model?

When I first hooked up an SS power amp, I thought "well obviously I don't need speaker compression because I have a real speaker".

But later when reading the FAS Amp block wiki, I saw quotes from Cliff there saying that it was advisable to use a little speaker compression with an SS power amp (but not tube). So now I have just a touch of speaker compression dialled in and I do think that it sounds better.

You need to scroll down a bit in the following section to see that quote from Cliff:

https://wiki.fractalaudio.com/wiki/index.php?title=Amp_block#SPEAKER_COMPRESSION
 
Hmm. Don't hate me for saying something this obvious @4406cuda, but could you simply dial back some presence in the model, given that it tends to affect between 2 and 3 KHz in Marshall amps? Then add a bit more regular treble using the treble knob. It's essentially a cut that's centered around that problematic 2.5 KHz frequency in the real amps, isn't it?

The knobs in the Axe-Fx don't exactly represent the numbered values on the amps, after all; so perhaps the model in your preset has ended up with more presence than you'd typically dial in when using a real tube amp in the real world?

Other than that, I've got nothing. Hopefully somebody more experienced can help.
 
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Hmm. Don't hate me for saying something this obvious @4406cuda, but could you simply dial back some presence in the model, given that it tends to affect between 2 and 3 KHz in Marshall amps? Then add a bit more regular treble using the treble knob. It's essentially a cut around that problematic 2.5 KHz frequency in the real amps, isn't it?

The knobs in the Axe-Fx don't exactly represent the numbered values on the amps, after all, so perhaps the model in your preset has ended up with more presence than you'd typically dial in when using a real tube amp in the real world?

Other than that, I've got nothing. Hopefully somebody more experienced can help.
I appreciate your help. I usually don't keep the presence higher than 5, sometimes as low as 2. I also have tried cranking the mid and bass, and lowering the treble to two. Depends on if the bright cap is engaged or not.

Thanks!
 
Hi,

You could also add a multi band compressor, setup to surgically compress a narrow band around the offending frequency.
Thanks
Pauly

I would like to determine the cause. I do not see many posts on this forum about it and I am wondering if it is how I configuring and connecting my AXE III.

I have the same issue with all my guitars with have passive medium output humbuckers. On all my guitars and on most of my presets there is this noticeable annoying frequency around 2.5K. It is "metallic plinky" sound. Also, it seems that I am constantly having to tame higher end frequencies without making the tone sound like there is a blanket on it.

I have tried different cables and I prefer Mogami cables. I also have tried different speakers and prefer Creambacks or the Lead 80.

I was initially using a Fryette Power Station and then the Fryette LXII before I got the Matrix.

I am running a 20' cable to a Analog Man buffer --> 20' cable snake (includes XLR for FC-6) to rear input 1 --> Output 2 --> Matrix GT1000 --> either a pair of 2x12 cabs or a pair of 1x12 cabs. My cabs have Creamback 65s or Alnico Creams

I play a variety of rock covers using Fenders and Marshalls, mostly. I use individual presets and scenes for each song that are created at band volume. All my presets are set to SS Amp with Cab. I have tried many impedance curves, but lately the 4x12 Greenbacks are sounding the best.

I usually start by limiting the input frequencies on the amp block from ~100Hz to ~6Khz. I occasionally use the 10 band output eq to lower the extreme low and highs. Occasionally, I have to turn off the bright switch for the Marshalls. I have played bright cap values. I occasionally run a ParaEQ after the amp block lower the 2.5K frequency -6db with a tight Q.

I use very little to a moderate amount of delay, very little reverb, compressor for cleans, and modulation when it is needed. I use my ears and the leveling tool.

A little about me: I have been playing guitar for about 45 years, both as a hobby and semi professionally. I am currently playing in two working cover bands. I currently own a Friedman BE 100 Deluxe, but would prefer to use the AXE III after it is dialed in. In the past I have owned an FX8 and AX8. I also have owned too many amps over the years.

Thank you Cliff and team for your great work and thank you in advance for anyone's suggestions.
 
Hi,

You could also add a multi band compressor, setup to surgically compress a narrow band around the offending frequency.
Thanks
Pauly
I have tried the multiband compressor, but I couldn’t figure out how to set it correctly. I might have to spend more time with it.
 
@4406cuda I have the exact same problem as you, with exactly the same amp models (classic Fender + Marshall). This was immensely annoying for me, since I tried for weeks to fix this. I think I have roughly identified the problem recently. Let me describe it below.

I noticed the problem is not present at all with my Gibson SG, but with my Ibanez JS2410 the sound of the A string is horrible. So I sampled the raw input of the A string on both guitars and did a frequency spectrum analysis. If you have a look at the attached diagram, you can see that the Ibanez has a lot more pronounced overtones in the range of 2.5 kHz. I investigated this, and my impression is that the reason is a combination of the acoustic sound of the guitar with the position of the neck pickup, which seems to make this frequency range very prominent. (I tried to move a similar pickup to different positions on the neck and noticed that the chosen positioning is kind of "worst case" amplifying the frequencies around 2.5 kHz, while at other positions the problem disappears.)

When I use a parametric EQ block before the amp block and use a peaking filter with -10 dB and Q around 3.5 at 2.4 kHz, the sound becomes OK. Of course, this is kind of a strong change in a frequency range that is very important for the overall sound, and I wished I could have achieved this with lesser tweaking, but that is the best I was able to achieve. As mentioned, with my Gibson SG I don't have to do anything here, the sound is very good without any EQ-ing.

So I somehow had a first impression of what causes the problem, namely pronounced overtones of the guitar. To further investigate this, I had a look at the influence of the bright switch and bright cap value for the Fender and Marshall amp models. From what I know, the early Marshalls like JTM 45 I like to use are very similar to Fender amps of that time. This might be an explanation for why the problem appears with these models.

By switching off power amp modeling, I was able to see that the problem actually appears before the power amp stage. The annoying frequencies are created in the input/preamp stage with turned on bright switch and bright cap values above a certain threshold. So I tried to figure out what the influence of the bright cap is here. To this end, I placed a synthesizer block before the amp block, with a relatively low output level of something like -20 dB, according to the somehow lower levels of the annoying frequencies in the raw guitar signal, compared to the base frequencies. Then I tried different frequencies for a sine wave in the synth block and had a look at the shown output level in the grid overview, with bright switch off and on. I had the impression that for the amp models we are discussing, activated bright switch raises the frequencies we are talking about by a really large amount, which in case of my Ibanez seems to raise these frequencies to a level at which they become really annoying.

As a comparison, I tried my very old Line 6 POD 2.0 and it shows a similar behavior for the Ibanez, so I think the observed behavior is somehow "the truth", but I don't have access to a real tube amp to check this.

So to summarize, I think the problem might be caused by using a guitar model with pronounced overtones in the frequency range we are talking about, and that we are observing a somehow accurate amp/cab modeling here, i.e., what we get is simply how the guitar + (simulated or not) amp sounds like.

However, I hope that I am wrong with this, since I would like to get a good sound without using such a strong EQ-ing of my raw guitar signal. Turning off the bright switch is also not a really nice solution, since I found it is not trivial for me to EQ the signal by other means (parametric/graphical EQ) to get the desired overdriven sound with correct amount of "bite".

So I would appreciate any hints which could help me to improve things here, or also falsifying or supporting my observations a lot! Intuitively, I think it is somehow strange if there are some guitar models which sound very nice and some which sound totally crappy und unusable for these simple amps like classic Fender and Marshalls!
 

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Have you tried different rooms? Smaller rooms with untreated walls can give a flutter echo with comb filtering around this frequency.
 
@4406cuda I have the exact same problem as you, with exactly the same amp models (classic Fender + Marshall). This was immensely annoying for me, since I tried for weeks to fix this. I think I have roughly identified the problem recently. Let me describe it below.

I noticed the problem is not present at all with my Gibson SG, but with my Ibanez JS2410 the sound of the A string is horrible. So I sampled the raw input of the A string on both guitars and did a frequency spectrum analysis. If you have a look at the attached diagram, you can see that the Ibanez has a lot more pronounced overtones in the range of 2.5 kHz. I investigated this, and my impression is that the reason is a combination of the acoustic sound of the guitar with the position of the neck pickup, which seems to make this frequency range very prominent. (I tried to move a similar pickup to different positions on the neck and noticed that the chosen positioning is kind of "worst case" amplifying the frequencies around 2.5 kHz, while at other positions the problem disappears.)

When I use a parametric EQ block before the amp block and use a peaking filter with -10 dB and Q around 3.5 at 2.4 kHz, the sound becomes OK. Of course, this is kind of a strong change in a frequency range that is very important for the overall sound, and I wished I could have achieved this with lesser tweaking, but that is the best I was able to achieve. As mentioned, with my Gibson SG I don't have to do anything here, the sound is very good without any EQ-ing.

So I somehow had a first impression of what causes the problem, namely pronounced overtones of the guitar. To further investigate this, I had a look at the influence of the bright switch and bright cap value for the Fender and Marshall amp models. From what I know, the early Marshalls like JTM 45 I like to use are very similar to Fender amps of that time. This might be an explanation for why the problem appears with these models.

By switching off power amp modeling, I was able to see that the problem actually appears before the power amp stage. The annoying frequencies are created in the input/preamp stage with turned on bright switch and bright cap values above a certain threshold. So I tried to figure out what the influence of the bright cap is here. To this end, I placed a synthesizer block before the amp block, with a relatively low output level of something like -20 dB, according to the somehow lower levels of the annoying frequencies in the raw guitar signal, compared to the base frequencies. Then I tried different frequencies for a sine wave in the synth block and had a look at the shown output level in the grid overview, with bright switch off and on. I had the impression that for the amp models we are discussing, activated bright switch raises the frequencies we are talking about by a really large amount, which in case of my Ibanez seems to raise these frequencies to a level at which they become really annoying.

As a comparison, I tried my very old Line 6 POD 2.0 and it shows a similar behavior for the Ibanez, so I think the observed behavior is somehow "the truth", but I don't have access to a real tube amp to check this.

So to summarize, I think the problem might be caused by using a guitar model with pronounced overtones in the frequency range we are talking about, and that we are observing a somehow accurate amp/cab modeling here, i.e., what we get is simply how the guitar + (simulated or not) amp sounds like.

However, I hope that I am wrong with this, since I would like to get a good sound without using such a strong EQ-ing of my raw guitar signal. Turning off the bright switch is also not a really nice solution, since I found it is not trivial for me to EQ the signal by other means (parametric/graphical EQ) to get the desired overdriven sound with correct amount of "bite".

So I would appreciate any hints which could help me to improve things here, or also falsifying or supporting my observations a lot! Intuitively, I think it is somehow strange if there are some guitar models which sound very nice and some which sound totally crappy und unusable for these simple amps like classic Fender and Marshalls!

Interesting analysis and good work. I have struggled with the metallic sound as well. The only way to get around it is to bleed off highs. I suspect your SG has warm sounding pickups in comparison to your other guitars. I make presets for guitars and not all my guitars will sound good on a preset not made for it.

I kill highs in various ways. The bright cap on Marshalls is too much at low gain levels. This is the way those caps work, they have a smaller effect as the drive is increased. So I turn it off or change the value. The plate frequency controls in the preamp can bleed off highs and you can lower those settings. The high frequency on the speaker page can be lowered. There are many ways to eq, but the trick is to cut without killing your tone. Running through a FRFR doesn’t help because of the tweeters. Conversely you can warm up tone by increasing low frequency response to make the high peaks seem to be less prominent. Use darker IRs or increase the mic distance in the cab block. I never used to use the tone controls on the guitars but now I do. Especially on P90’s which I use a lot, I like to roll the tone down a bit.

Some amps just don’t sound good with certain guitars. So use another amp. I’m no expert but I’m happy with my current batch of presets. I managed to get rid of that metallic ringing sound for the most part.
 
@4406cuda I have the exact same problem as you, with exactly the same amp models (classic Fender + Marshall). This was immensely annoying for me, since I tried for weeks to fix this. I think I have roughly identified the problem recently. Let me describe it below.

I noticed the problem is not present at all with my Gibson SG, but with my Ibanez JS2410 the sound of the A string is horrible. So I sampled the raw input of the A string on both guitars and did a frequency spectrum analysis. If you have a look at the attached diagram, you can see that the Ibanez has a lot more pronounced overtones in the range of 2.5 kHz. I investigated this, and my impression is that the reason is a combination of the acoustic sound of the guitar with the position of the neck pickup, which seems to make this frequency range very prominent. (I tried to move a similar pickup to different positions on the neck and noticed that the chosen positioning is kind of "worst case" amplifying the frequencies around 2.5 kHz, while at other positions the problem disappears.)

When I use a parametric EQ block before the amp block and use a peaking filter with -10 dB and Q around 3.5 at 2.4 kHz, the sound becomes OK. Of course, this is kind of a strong change in a frequency range that is very important for the overall sound, and I wished I could have achieved this with lesser tweaking, but that is the best I was able to achieve. As mentioned, with my Gibson SG I don't have to do anything here, the sound is very good without any EQ-ing.

So I somehow had a first impression of what causes the problem, namely pronounced overtones of the guitar. To further investigate this, I had a look at the influence of the bright switch and bright cap value for the Fender and Marshall amp models. From what I know, the early Marshalls like JTM 45 I like to use are very similar to Fender amps of that time. This might be an explanation for why the problem appears with these models.

By switching off power amp modeling, I was able to see that the problem actually appears before the power amp stage. The annoying frequencies are created in the input/preamp stage with turned on bright switch and bright cap values above a certain threshold. So I tried to figure out what the influence of the bright cap is here. To this end, I placed a synthesizer block before the amp block, with a relatively low output level of something like -20 dB, according to the somehow lower levels of the annoying frequencies in the raw guitar signal, compared to the base frequencies. Then I tried different frequencies for a sine wave in the synth block and had a look at the shown output level in the grid overview, with bright switch off and on. I had the impression that for the amp models we are discussing, activated bright switch raises the frequencies we are talking about by a really large amount, which in case of my Ibanez seems to raise these frequencies to a level at which they become really annoying.

As a comparison, I tried my very old Line 6 POD 2.0 and it shows a similar behavior for the Ibanez, so I think the observed behavior is somehow "the truth", but I don't have access to a real tube amp to check this.

So to summarize, I think the problem might be caused by using a guitar model with pronounced overtones in the frequency range we are talking about, and that we are observing a somehow accurate amp/cab modeling here, i.e., what we get is simply how the guitar + (simulated or not) amp sounds like.

However, I hope that I am wrong with this, since I would like to get a good sound without using such a strong EQ-ing of my raw guitar signal. Turning off the bright switch is also not a really nice solution, since I found it is not trivial for me to EQ the signal by other means (parametric/graphical EQ) to get the desired overdriven sound with correct amount of "bite".

So I would appreciate any hints which could help me to improve things here, or also falsifying or supporting my observations a lot! Intuitively, I think it is somehow strange if there are some guitar models which sound very nice and some which sound totally crappy und unusable for these simple amps like classic Fender and Marshalls!
You probably know this, but I just want to clarify what the bright switch and bright cap actually do.

When the bright switch on, the bright cap bypasses the master volume control at high frequencies. In other words, it turns them all the way up. The bigger the cap, the stronger that effect is, and the further down in frequency it extends.

Net of this is that the higher your master volume, the less effect the bright circuit has. With master decked, the bright switch and cap do nothing.

Keep that in mind as you're balancing the various high end controls.
 
You probably know this, but I just want to clarify what the bright switch and bright cap actually do.

When the bright switch on, the bright cap bypasses the master volume control at high frequencies. In other words, it turns them all the way up. The bigger the cap, the stronger that effect is, and the further down in frequency it extends.

Net of this is that the higher your master volume, the less effect the bright circuit has. With master decked, the bright switch and cap do nothing.

Keep that in mind as you're balancing the various high end controls.
Note also that many Marshalls have huge bright caps, so if you leave that at the stock value, the amp will be way way bright, until you get the master pretty far up.

If you don't love that, turn it off, make it smaller, or turn the master up to keep up with all the highs that huge cap lets through. If you turn the master up, you can lower the gain to kind of compensate, or not.
 
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This is likely the resonant peak of your guitar pickups. You can shift the peak by using a longer/shorter cable or turning on the input capacitor in the Input Z. Or try a cable with different capacitance.
 
I always thought that frequency range was a big part of the signature electric guitar sound. A slight bump at 2k or so usually adds a little something that tubes amps did, at least to my ears. Also helps to cut when surrounded by other instruments. Different strokes, I guess?
 
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