5E3 question

[Leevi]

In my last 5E3 project I noticed that if I change the cap value between the 12AX7 triodes
it has a huge impact on the sound. I'm also using the Paul C mod there but the cap change from 22n to 33n
made the sound louder and gave more headroom. I know the role of the caps but I didn't image that big
difference. Any good clarifications?


Paul C mod:
http://music-electronics-forum.com/attachments/6119d1251750286-paul-c_mod_schematic_comparison.jpg


/Leevi

[shooter]

Any good clarifications

maybe just muddying the waters?  the coupling caps pass/block frequencies, the bigger the cap the larger band of freq gets thru un-molested, hence a *boost* in loud?

[sluckey]

You increased the cap size by 50%. More low frequencies will sound louder to most ears.

[6v6Pin1]

Will you describe the the change you heard after applying the Paul C mod?

[shooter]

More low frequencies will sound louder to most ears

not sure this isn't an apples and oranges thing, according to your link, the coupling caps are .02 on both, the difference is the 1meg and 2.2meg R.  I've never done *the paulC mod*, but I have changed coupling caps and as Sluckey stated, I get more boom, making it *louder*, fuller.....to a point, then it sorta muddies, or sounds shrill, finger-naily on a chalk board. 

[Leevi]

Will you describe the the change you heard after applying the Paul C mod? 

I can fully agree with this statement:


https://sites.google.com/site/yourtubeamp/mods-and-maintenance/paul-c-mod-for-princetons

  I get more boom, making it *louder*, fuller.....to a point, then it sorta muddies, or sounds shrill, finger-naily on a chalk board.

it's up to what kind of sound you're looking for


Leevi

[PRR]

> coupling caps are .02 on both, the difference is the 1meg and 2.2meg R.

Further: in the stock plan, the 1Meg is boot-strapped by the cathode, looks at least 10 times bigger, over 10 Meg. The divider plan is just 0.687 Meg.

Still, 0.02uFd into 0.687 Meg is 12Hz, 2 octaves below the lowest note you would reasonably expect a 5E3 to carry, so it should not be audible.

The bias is changed, which changes the maximum output of this stage. I suspect that 50V is below optimum and 102V is a bit high of optimum. However the 6V6 is not that hard to drive, and either bias ought to beat the 6V6s to the wall.

There may be a significant difference in OVER!-drive recovery. The stock plan, beaten beyond its limit, will bias-down, block, and recover slowly. The divider plan may recover quicker. I suspect Neil Young would know the difference on the first ping, because he knows *exactly* how his amp goes-into and recovers-from blocking. Mere mortals may hear a difference but be unable to explain just what they feel/hear.