5150 Presence Knob

[MirrorProfiles]

Rev. D of the schematic which was Jan. 15 2013 specs 30mA per tube. This was changed to 27.5 mA per tube somewhere between then and Dec. 11 2015. There apparently haven't been any changes to that spec since. So in the past 10 years every amp shipped has been at least 27.5 mA.

We talking OG 5150/6505 here?

I had a 2007 6505 prior to my Block Letter 5150, that one definitely arrived below 20mA. My 1992 Block Letter had been serviced before I bought it and the resistor that sets the bias had another resistor tacked on in parallel that made it way too hot. Clipping that out and returning it to stock gave me 19mA with some Tung Sol 6L6’s.

Again, subject to personal preference here but the 5150 tones I think of in my head are either from the 90’s or metalcore movement of the early 2000’s. I’d prefer that really cool bias and ideally some Svetlana 6L6’s like they originally came with. I’d imagine that would please the most people.

 

[FractalAudio]

We talking OG 5150/6505 here?

I had a 2007 6505 prior to my Block Letter 5150, that one definitely arrived below 20mA. My 1992 Block Letter had been serviced before I bought it and the resistor that sets the bias had another resistor tacked on in parallel that made it way too hot. Clipping that out and returning it to stock gave me 19mA with some Tung Sol 6L6’s.

Again, subject to personal preference here but the 5150 tones I think of in my head are either from the 90’s or metalcore movement of the early 2000’s. I’d prefer that really cool bias and ideally some Svetlana 6L6’s like they originally came with. I’d imagine that would please the most people.

5150 III.

 

[Daveporter33765]

Why nobody's complaining about the Brit 2203 Presence range?
0-9 has LESS range in dB than 9-10, yet nobody's asking for an ideal presence pot for the Brit 2203.

I declare this poll a complete bullshit, the vast majority of voters side with Fractal by default and actually couldn't care less either way.

2203 Presence:
View attachment 130816

The poll is what it is. Every vote was made by a forum member. Just because the result does not agree with your position on the issue does not mean the poll “is bullshit”. In addition, many of those NO votes may be coming from seasoned guitarists who have a great deal more experience with the use of actual amps than you do...a NO vote does not mean the person who cast that vote was young or inexperienced with “real” amps. I am 70 and have been a professional guitarist for over 50 years, I was modding amps since I was in my teens. I voted NO because I develop my own sounds using my ears and having a pot taper that gives me more ability to dial-in tones is a good thing in my opinion. So, each person here has a voice, and they are free to use it without ridicule or pressure from others. The results will be what they are and it will be Cliff that will interpret them.

 

[MirrorProfiles]

Yeah, I’d definitely go a little warmer on the EVH ones than the Peavey era amps. My cool bias posts were specifically about the older circuits

 

[Orvillain]

@FractalAudio
Out of curiosity, is this a general issue with all amps? I ask because we did the whole song and dance with the Satriani JVM right, and you redid the model using a production amp, which definitely got it closer to my real world one. However my real world one still gets brighter and brasher and more aggressive, particularly in that 1-3kHz region.

I didn't make a big thing about it because I knew loads of forumers would just jump in with "pot tolerance" explanations, which I think only goes so far when the knob travel at 10 on the Axe III still sounds darker than the real amp.

But I wonder if the presence on that one has been "fixed" as well??

 

[unix-guy]

I think Fractal should create a global "easy mode" that makes EVERYTHING in the Axe Fx ideal, all the Marshall become hot rodded and sound like Slash, all Fenders are are squiky clean, all VOXs sound like Queen, all Mesas sound like Metallica or Petrucci, etc., when all the controls set on 5.

I think you might be surprised how many people actually would want that!

 

[FractalAudio]

@FractalAudio
Out of curiosity, is this a general issue with all amps? I ask because we did the whole song and dance with the Satriani JVM right, and you redid the model using a production amp, which definitely got it closer to my real world one. However my real world one still gets brighter and brasher and more aggressive, particularly in that 1-3kHz region.

I didn't make a big thing about it because I knew loads of forumers would just jump in with "pot tolerance" explanations, which I think only goes so far when the knob travel at 10 on the Axe III still sounds darker than the real amp.

But I wonder if the presence on that one has been "fixed" as well??

Most models use authentic presence controls.

With an amp like the JVM it's very easy to saturate the virtual power amp. The real amp has two masters, a channel master and a global master. So the level in to the power amp is the product of those two masters. The model only has one so if you set the MV the same as the channel master and the global master isn't at 10 then you'll be overdriving the model's power amp much more than the amp. Just lowering the MV a touch will make the amp brighter for a given Presence value.

 

[Orvillain]

Most models use authentic presence controls.

With an amp like the JVM it's very easy to saturate the virtual power amp. The real amp has two masters, a channel master and a global master. So the level in to the power amp is the product of those two masters. The model only has one so if you set the MV the same as the channel master and the global master isn't at 10 then you'll be overdriving the model's power amp much more than the amp. Just lowering the MV a touch will make the amp brighter for a given Presence value.

Groovy. Will check that out. Sorry for the derail!

 

[unix-guy]

Even though the poll is leaning ideal, I'm personally leaning authentic.

You know the Mark series EQ is next on the chopping block, right?

If you're going authentic (which I have no heartburn over even though my personal preference is ideal) then I think it's gotta be a holistic approach or you're going to get bombarded with complaints/questions...

Although, you already are, so what do I know?

 

[rcm78]

Definitely authentic. Looking at the graph James Freeman posted the “ideal” anti log pot will be abrupt compared to the log pot. People will claim the model is harsh, thin, and brittle. I can see the YouTube videos now.

 

[FractalAudio]

Groovy. Will check that out. Sorry for the derail!

This is just one example of all the little variables that people don't realize when comparing a real amp to a model. In this particular case I agonized over it a bit. At first I was thinking "well, model it as though the global master is at noon". But then I'm thinking "shit, someone will turn both masters to 10 and complain that the model doesn't sound the same". So I modeled it with the global master on 10.

 

[unix-guy]

This is just one example of all the little variables that people don't realize when comparing a real amp to a model. In this particular case I agonized over it a bit. At first I was thinking "well, model it as though the global master is at noon". But then I'm thinking "shit, someone will turn both masters to 10 and complain that the model doesn't sound the same". So I modeled it with the global master on 10.

Is it possible to expose that to users?

 

[rcm78]

Even though the poll is leaning ideal, I'm personally leaning authentic.

Cliff, I’m sure you’re aware you have a cult like following on this forum.
The original post was leading. You claimed the original pot was incorrect and you fixed it. Then asked what we wanted.
Asked in an objective manner the results would have been different.

 

[sprint]

Definitely authentic. Looking at the graph James Freeman posted the “ideal” anti log pot will be abrupt compared to the log pot. People will claim the model is harsh, thin, and brittle. I can see the YouTube videos now.

But again I'd ask: does going with ideal mean that there are authentic setting values that are not available / not possible (as per those graphs posted)? Or does ideal just mean the taper in delivery rate is different across the knob range? A key question no? (for those of us who've not
owned the real amps but want to get those sounds we hear from them in the case of ideal mode tapers).

 

[FractalAudio]

Cliff, I’m sure you’re aware you have a cult like following on this forum.
The original post was leading. You claimed the original pot was incorrect and you fixed it. Then asked what we wanted.
Asked in an objective manner the results would have been different.

I stand by my opinion that the pot is incorrect.

 

[FractalAudio]

But again I'd ask: does going with ideal mean that there are authentic setting values that are not available / not possible (as per those graphs posted)? Or does ideal just mean the taper in delivery rate is different across the knob range? A key question no? (for those of us who've not
owned the real amps but want to get those sounds we hear from them).

Taper only affects where on the knob the sounds occur.

 

[rcm78]

But again I'd ask: does going with ideal mean that there are authentic setting values that are not available / not possible (as per those graphs posted)? Or does ideal just mean the taper in delivery rate is different across the knob range? A key question no? (for those of us who've not
owned the real amps but want to get those sounds we hear from them in the case of ideal mode tapers).

It’s hard to answer without using/hearing both.
The range of presence available should be the same but acc to the graph, 50% on the Log taper is equal to .5% on the antilog.
By eye it looks to reverse the taper and move most of the curve to the beginning. By ear it may be different. I’m not an amp builder.
I do have an original Peavey 5150 and always set the presence around 6. If I did that with an idealized model I’d move on.

 

[jakel]

I voted for ideal, but after reading all the posts I’ve changed my mind. Authentic is the way to go. It’s more consistent with your well-known philosophy, and what York Audio and others said about those familiar with the real amp.

 

[James Freeman]

You know the Mark series EQ is next on the chopping block, right?

Well that's super easy, make another output eq model and let people use whatever they like.
Status quo with benefits, win-win.

 

[DJD100]

It's very interesting to see that people who have a lot of experience with real amps vote for authenticity.
Decedes long familiarity and preservation is exactly right.



https://forum.fractalaudio.com/threads/accurate-knob-dial-position.199912/

Sorry, this is just BS James, as many say they haven't played this specific tube amp (myself included, as I'm not a super big gain guy), not that they haven't played tube amps in general.

In case you haven't noticed, "IDEALIZED" is winning big for this specific parameter on this specific amp model, as even the OEM rectified their pot taper mistake in their later models.