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Can someone check this out? (JTM 45)

johna156

Inspired
Hey, so I was trying to get a similar tone to Gary Moore's still got the blues, using the plexi trebble patch. I just switched the amp to JTM 45 and used a fat rat drive (to try and come close to the guv'nor originally used by GM). I ended up with an awesome lead sound, which clears up nicely, has a nice singing sustain with excellent note bloom etc. I was very happy, until I noticed that when I played the D string at the 12th fret using the neck humbucker, I was getting some kind of strange overtones, like a constant ghost note ringing... I tried the following to solve the problem:
Professionally set up the guitar (all of my guitars to be exact), pickup height adjustment and individual pole screw adjustment (lowering it). Problem didn't get solved with this. Actually all of my guitars excibit this same thing with this patch and settings etc. (the guitars don't have any fret buzz or intonation problems, everything works perfectly, just took them back from my luthier)
I played with the low cut / hi cut to no avail (kind of expecting that).
Tried to tweak basic settings on the drive sim and amp sim (to no avail again).
Then I went to the advanced settings and started tweaking some params.
It seems that the problem goes away when I tweak (one or both of) these advanced settings:
a) Lower the supply sag to about 1
b) Change the Voltage from 60Hz to 30Hz or lower.
It's really strange, as I can hear the "ghost" note changing pitch as I change the Voltage value from 60 to 30Hz with every step of 5hz changing the pitch of the sound...

I finally ended up lowering the sag to about 1 and upping the level at the drive sim to restore some hair I had lost because of the lower sag value.
This seems to have fixed the problem, but I was wondering if this is some kind of bug or if it is normal, so I decided to post it, just in case someone else might be having the same problem.

Now, I can't upload the patch, but I can tell you how it is set up so that you guys can check it out.
I just used the plexi trebble patch, replaced the amp with the JTM 45 model, bass at 12 o'clock, trebble and middle cranked (bright on), presence at around 1 o'clock, master at 9-10, drive at 5.8, modern voicing.
For the drive, I used the fat rat with drive at 10-11 o'clock, level at about 3 o'clock (with the supply sag at 4.8 that is, with the supply sag at 1 I had to almost crank this), tone at 1-2 o'clock and at the eq page of the drive sim, I set the mid freq to 500Hz and pushed it all the way (I think all the way, I can't check now since I'm nowhere near the axe).
For the cab block I used the default that came with the patch (I think stereo green tv mix?).
I also use in my patch 2 mono tape delays in series after the amp and a reverb block. Of course the problem was there with the effects both on and bypassed (meaning it was still there with just using the drive/amp/cab blocks).

Anyway, lowering the sag, fixed it for me, although I don't get exactly the sound I was looking for (the one I really liked would be with the supply sag set to default values which was sth like 4.8 IIRC).
Sorry, I can't upload patches (my axe is nowhere near a computer), but if anyone's interested, please try the above settings and check it out.
I listen through a pair of Yamaha HS80M.
Guitars being used (all excibiting the same behaviour):
Epiphone les paul tribute + with Gibson classic 57's pafs
Warmoth custom made superstrat with Bareknuckle VHII pafs
Yamaha custom reconstructed 1212s superstrat with SD mini 59 and Bareknuckle VHII
I don't have the same problem in any other patch as far as I can tell.
Thanks in advance guys, have a good one...
 
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jeppekristoffer

Power User
What's the settings of your B+Time Constant parameter?
This is from the release notes from fw 10. "Note that high values of Sag along with low B+ Time Constant values can cause “ghost notes” when the supply type is AC (as in a real amp). Lower B+ Time Constant values
will make the amp feel “faster” but too low can cause ghost notes."
 

johna156

Inspired
Yeah, forgot to write about that, that was actually the very first thing I tried to adjust after using the default settings (with which the problem was present).
I raised the B+ which helped, but only when I really cranked it (at about 3+ o'clock), which made the amp too "stiff" and far off from what I was looking for feeling-wise (and sound-wise).
So I returned the B+ to default settings (or close to default) and started tweaking other params that I felt were "connected" to the issue. I also tried transformer match, but again, in order to make the ghost note go away I had to use extreme settings which didn't sound good.
So, I ended up adjusting the sag and the Voltages.
Of course, when using DC instead of AC, the problem goes away, as it also does by reducing the Volts from 60Hz to about 30Hz IIRC (and with every 5Hz step the pitch of the ghost note was changing until it went away at around 25 or 30Hz).
However, I settled with leaving the Volts at default (60Hz) and lowering the supply sag (this seemed to me to alter the sound as less as possible compared to the other "solutions" I tried).
 

johna156

Inspired
Also, keep in mind that this "ghost note" seems to only appear when using the D string on the 12+ fret, which originally had me thinking that it was my guitars' fault, until I had them set up professionally and found out that the problem was still there. Then I lowered the pole screw which also didn't change anything, so finally I started tweaking the advanced params...
 

johna156

Inspired
Like I said, can't record anything at the moment, or upload presets.
After tweaking the sag, the problem goes away, I just started the thread in case someone else is having the same problem AND to check if this is normal behaviour for this amp model or not.
 

jeppekristoffer

Power User
Oops sorry, missed that you couldn't upload.
I use this amp alot and I tend to get lots of overtones and harmonics which make me have to work on dampen the strings with my right hand to prevent lots of ringing when not playing. Is that what you are talking about or do you mean other types of ghost notes?
 

johna156

Inspired
No, it's not a matter of technique.
If I mute every other string and just play at the 12th fret on the D string, I can clearly hear what appears to be a "ghost" note in the background, which is not exactly a note, but like a steady overtone that you can listen for as long as you let the note ring. And as you lower the voltage it sounds like it's changing pitch (lowers pitch) until it disappears when you go to about 25-30Hz. If instead you choose to lower the supply sag, you don't hear the "change of the pitch", but rather the "ghost note" slowly disappearing as you turn the sag down (almost like turning its volume down, until you can't hear it when sag is set to around 1).
 
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FractalAudio

Administrator
Fractal Audio Systems
Moderator
Those old amps make ghost notes. My 100W Plexi has some ghost notes that are louder than the fundamental.

The easiest way to eliminate them (if you don't like/want them) is to simply set the Supply Type to DC.

However, IMO, the ghost notes are a large part of the character of these designs and removing them isn't desirable. Don't over-analyze it. Recognize that certain designs produce ghost notes and embrace it.
 

barhrecords

Axe-Master
Those old amps make ghost notes. My 100W Plexi has some ghost notes that are louder than the fundamental.

The easiest way to eliminate them (if you don't like/want them) is to simply set the Supply Type to DC.

However, IMO, the ghost notes are a large part of the character of these designs and removing them isn't desirable. Don't over-analyze it. Recognize that certain designs produce ghost notes and embrace it.
yes!

This change (the AC power supply?) really really really takes the amp sims to the next level and beyond. Just placing a plexi amp block and almost any cab block produces a KILLER realistic tone. It's truly astounding.
 

johna156

Inspired
yes!

This change (the AC power supply?) really really really takes the amp sims to the next level and beyond. Just placing a plexi amp block and almost any cab block produces a KILLER realistic tone. It's truly astounding.
That's good to know Cliff, thanks for the reply!
I actually owned a 100w super lead plexi from '73 but hadn't noticed this behaviour. But, to be fair, that amp had a trany replaced, so maybe that's why I couldn't hear the ghost notes.
I had read before in another thread a similar "problem" and since I found the solution, I thought I should just post it, that's all.
TBH, you couldn't possibly make out this ghost note in a mix. I just felt it was strange that the pitch was changing with the voltage selection, so just wanted to know if it is normal or not...
Oh, btw, Cliff, the plexis and the JTM 45 are exactly what I've been looking for both sound and feel-wise, for the last 24 years of playing the guitar.
At last I can have my authentic cranked plexi sound with some of the best effects around at ANY volume level... Just priceless... So, yeah, thank you very much once again from one extremely satisfied customer.

P.S. The plexi 50 just kills...
 
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