that "light" feeling.....

[12AX7]

....or maybe the better word, "transparency". I wish it were easier to describe tone. But in this case it's tone to a smaller degree than feel. I never see this talked about unless it's what people call transparent. To me thats part of it but not completely. I want to see what others have to say n this subject if anyone can indeed understand what i'm describing. It's a tone that make the strings feel light as tho theres less weight behind the note. What i think is considered transparent. If anyone has followed up to this point and gets what i'm saying, do you know in technical terms what causes it? And don't get me wrong, i'm not saying whether it;s good or bad, but personally i like it to some degree. I've created this feel/tone many times while tweaking cascaded gain stages but I don't recall what it was that caused it. Today i tried something that caused it big time. I have a 500pf/470k peaking filter in whats basically a 3 stage preamp with a 4th that is a cathode follower, so it's like a jcm 800 master volume amp but no cold bias stage. there was only one peaker and it was right after the 2st coupling cap into the gain pot. If i bypass that peaker of course the tone is wollier and a bit more gain. But other than that no real change in character. Then i tried putting a second one right at the pot's output. I use the amp with the gain pot at about 2:00 by the way. Anyways, i put the same value peaker there and that light feel, that transparent quality, whatever u wanna call it came on like gangbusters. I tried both peakers at once, one at a time. But as long as that one after the pot was not bypassed it felt like all of a sudden i was running a .008 set of strings instead of the 10's i use.

I guess i posted this out of curiosity, not being very technically knowledgeably in electronic theory at all i'm curious if someone who knows what i'm describing can tell me in laymans terms as much as possible why the pre pot peaker does a very different thing than the post one. Also curious if anyone is very familiar with this tone/feel and consciously shoots for it or opposite when tweaking.

[drgonzonm]

Some of us are graphically inclined.  Could post a picture of your schematic?  Colors would help. 

Thanks. 

[sluckey]

Transparency doesn't show up very well on colored schematics.

[Willabe]

Transparency doesn't show up very well on colored schematics.

Depends on if your CAD program has the option of opaque or translucent in the color drop box. 

[John]

I imagine what you're hearing or feeling is the frequency and certain harmonics. Maybe very hard to quantify. "Feel" is something almost impossible to describe. And really, I"m the wrong one to chime in (har har) since I try to use the bare minimum parts count on my builds. Most of 'em don't even have a tone knob. 

[sluckey]

This is a good example of what I was trying to say. Each tube has a different level of transparency. I think it's safe to say that 100% transparency does not show up very well on colored schematics.

[drgonzonm]

Transparency doesn't show up very well on colored schematics.

But the colors do plus 1 to Willabe, my cad settings show white as black. 
I have down loaded many tif drawings, that are black on white, then converted the white to transparent.  This allows me to overlay over other drawings to determine differences.

12ax7,
I understood the direction you were headed.  That's why I was asking for a schematic.  Any changes you make to the original might allow or enlighten us to what is happening in the amp.  The written directions has my head spinning. 

Steve,
Your posting shows what happens when, we are using the same word, for very different descriptive meanings.  If I were to guess, 12ax7's transparency would be a form of a ghost note effect.  John used a different interpretation to the word transparency.  As a matter of fact, I download colored tifs as black and white, so I, can use the transparency feature, so I my backgrounds are transparent.   

[12AX7]

Basically just like this JCM 800except for the following differences...
1-V1A has 1.5k/.68 cathode instead of 2.7k
2-cold bias stage is instead a gain stage just like V1A
3-filters are 22uf

And the second 470k/500pf peaker is after the gain rather than at the grid of V2A. The PI not shown here is exactly the same and the PA is configured the same cept for the 18w trannies and 6V6. But all that matters is the preamp because thats where the tweaking and changes i mentioned happen.

[PRR]

> theres less weight behind the note

In audio "bass is heavy".

The 0.68uFd against 1.5K||cathode makes everything above 400Hz about twice as loud as everything below 250Hz.

The 470pFd with a couple 470K makes everything above 1,500Hz about twice as loud as everything below 1,000Hz.

You have the "light", "insubstantial" high overtones significantly stronger than the "heavy" bass you would get through a "flat" amp.

You can't compute the effect on the ear. A hot iron and well-stocked parts box are your friends.