Old presence circuits vs new standards vs alternatives

[Roberto]

Hello everybody,

while explaining the difference in the various presence configurations to an user on another forum, I came out with some sims. Here you can find them, I hope they can be helpful to someone:

- old scratchy 5k + 100n;
- new 4k7 // 25k+100n;
- my 4k7 // 10k+100n;
- unused 4k7 // 5k+100n.

The last plot has been done just to enhance the quantity of presence that is always present with the current configuration in Marshalls, and the less linear effect the pot has.

The 4k7 // 25k+100n is the standard one used in modern Marshall and many other amps, but lacks of linearity, and control, as only the last degrees of the pot have a real influence on the sound, so less control on presence, and less nuances.

[Gregg]

The 4k7 // 25k+100n is the standard one used in modern Marshall and many other amps, but lacks of linearity, and control, as only the last degrees of the pot have a real influence on the sound, so less control on presence, and less nuances.

This is correct BUT only IF you use a linear pot. Not so if reverse log pot is used.
Note that for many years now most companies are using a 10k, rarely a 25k reverse log pot in that type of Presence arrangement.
Note also that these days reverse log pots are readily available from many sources so they should be mandatory in that position for builders as well.

[Roberto]

"Should", but never happens.

Just because 25k lin is the same used in other places on the amp (EG mid pot) and so on a big production point of view, if you buy 2 millions pot of the same kind, you pay them way less than 1 million pots for each one of the king of tape.

That's why you can find zillions of amp with the 25k lin pot there, and no one afaik with the revlog, on big mass production amps.

In any case, even with the revlog, you'll never remove the slight presence you still have on zero.

[Gregg]

On the contrary - it happens from a long time and you can see it in the schematics. Think Marshall, Peavey etc. As a builder I'm also using them from a long time.
You don't need to buy 1 million pots to get descent discounts from the factory so it doesn't make any difference whether you buy 1 million rev log and 1 million linear pots or 2 million linear pots.
You're right you can't remove the slight presence on zero but that applies more to the 10k pot than to the 25k one. And if that "slight presence" is bothering you then maybe you don't need a presence pot at all.

[Roberto]

Gregg, can you tell me which amps have those antilog pots?
I've seen alot of schematics, and I've opened alot of amps during the years, but I've always seen lin pots there.
I'm talking about Marshall, Soldano, etc...

[Gregg]

Here are few amps that come to mind:
1/ PEAVEY - Classic 50, JSX, Valveking. Although not made by Peavey - EVH50.
In the 5150/6505 series the pots are labeled as 10k audio but maybe this is a mistake because a log pot would have even worse response than a linear one.
2/ MARSHALL - JVM410, JVM410HS,
3/ MESA - RoadKing, Stiletto

These qualify as mass production amps. I've seen it in other amps as well but this is enough for a start.

In Europe maybe Banzai carries the largest selection of pots including several rev log types.
In US Smallbear comes to mind so it's not difficult to get those at all.

[Roberto]

Perfect.

So you agree with me that are really a few number.

All previous Marshall have it linear. Other Mesa (the 'ctifier saga) have it linear.
Most of other amps as well (Diezel, Bogner, Soldano, Framus, Laney, CAE, Randall, Fryette, VHT, and so on).

Maybe it's not clear enough.
I don't want to start a debate on presence yes/no, nor old vs new, or how it can be improved, or if you think that I need a presence pot or not.
It's just a simple, easy, fast way to answer to questions that newbies can take alot of pages of explication to understand (I can send you the link of the other discussion on another forum).

Thanks for your understanding.

[Gregg]

OK, I will correct my previous statement from "most" to "many" although most of the companies you listed are not exactly the mass production type. If by any chance you have their sales numbers I would be curious to compare them with the ones I mentioned.

What newbies must remember is that the "usual" 25k presence pot should be reverse log. 25k or 10k is your choice.
Whether the biggest companies are using it or not is entirely their problem. The fact that they are still using linear pots doesn't make this a standard and that can be easily verified by anyone by performing a simple A/B test between both types of pots.

[Roberto]

That is becoming really funny.

Take a look at where your "mass production" peavey is....

[eschertron]

[ATTACH=CONFIG]43437[/ATTACH]

What is your source? I'm NOT disputing you, I am eager to see more industry data

[Enzo]

Not only what is the source, ,but also what does the graphic depict? Total sales? Sales of just guitar amps? Sales of amps with presence controls? Most favored companies by consumers?

If that is sales, then it says Orange sells three time what PV does?

And if you are talking a million pots, there are levels of scale. A company like Peavey buys millions of parts, and that fact that some other company like Fender buys even more parts doesn't change the economy of scale at Peavey. They are a mass producer by any standard.

[Roberto]

The thread is about guitar amp's presence pot,
In the guitar amp section of the forum.
What do you think is the right reference? Pineapple juice?

Guys, stop trolling ans answer to the question: how many guitar amps use antilog and how many linear pots for the presence?
By now I've seen a log pot (not antilog), so only four amps.
How many other amps works with linear pots?

Then, if you claim not to be trolls, just post a sim of the antilog.
That's all.

Thanks folks.

[Enzo]

Now we are trolls? I think it is a simple and fair question: what does your graphic depict, and where did it come from? I may be ignorant myself, but I can't tell if the graphic makes your point or is irrelevant to it.

[g1]

What is your source? I'm NOT disputing you, I am eager to see more industry data

The graph depicts total number of orders on reverb.com exclusively.
https://reverb.com/ca/news/the-best-...g-amps-of-2016

[Roberto]

Now we are trolls?

I'm moderator on various forums since early 2000s, one of them is slocloneforums, so I know quite good trolls.
I don't really think you are intentionally trolling, but the behaviour is the same.
Let me show you why:

I think it is a simple and fair question: what does your graphic depict

I've written as the incipit of the whole thread: Old presence circuits vs new standards vs alternatives

while explaining the difference in the various presence configurations to an user on another forum

So it is clearly explained. If you don't want to read the threads, don't answer just to make some noise.

and where did it come from?

I've again written as the incipit of the whole thread: Old presence circuits vs new standards vs alternatives

I came out with some sims.

Furthermore, on the data of the plots, you can see that they have been simulated and plotted few minutes before the post.
So it is again clearly explained. If you don't want to read the threads, don't answer just to make some noise.

I may be ignorant myself, but I can't tell if the graphic makes your point or is irrelevant to it.

I've written one more time as the incipit of the whole thread: Old presence circuits vs new standards vs alternatives

The last plot has been done just to enhance the quantity of presence that is always present with the current configuration in Marshalls, and the less linear effect the pot has.

The 4k7 // 25k+100n is the standard one used in modern Marshall and many other amps, but lacks of linearity, and control, as only the last degrees of the pot have a real influence on the sound, so less control on presence, and less nuances.

So it is one more time clearly explained. If you don't want to read the threads, don't answer just to make some noise.


Here you are changing the words to create again some noise:

And that fact that some other company like Fender buys even more parts doesn't change the economy of scale at Peavey. They are a mass producer by any standard.

These qualify as mass production amps. I've seen it in other amps as well but this is enough for a start.

That is totally different.


Just to confirm that it's your standard way of operating, let's take a look at the other thread:

But "same thing" requires me to scan through teemu's entire book looking for what you might be referring to

I've again written as the incipit of the whole thread: Floating ground dual class amplification A + B/C/D/etc...

another idea that came to my mind while reading this:
http://www.thatraymond.com/downloads...ttala_v1.0.pdf
(see page 112)

So it is again clearly explained that you don't have to read the whole book, as I've linked the precise page.
If you don't want to read the threads, don't answer just to make some noise.

while a block diagram answers most questions in seconds

I've again written as the third post of the thread: Floating ground dual class amplification A + B/C/D/etc...

Sure, tomorrow I'll sketch that, but it's really just the same thing of the linked book, just with the A class switched to vacuum.

One more time, if you don't want to read the threads, don't answer just to make some noise.


Now, you have made all this noise, and what plus have you given to the threads?
This is trolling, even if it's not your clear intention.

Thank you Enzo.