Tube DIY Asylum Do It Yourself (DIY) paradise for tube and SET project builders.

---

[ Follow Ups ] Thread: [ Display  All  Email ] [ Tube DIY Asylum ]

---

[ Alert Moderator ]

---

Re: Sweetness VS Load Lines

Posted by Naz (A) on August 8, 2006 at 17:11:34

In Reply to: Re: Sweetness VS Load Lines posted by danlaudionut on August 8, 2006 at 06:44:53:

>Plate resistance is 100H choke and since it's
directly coupled to the grid the load impedance
is near infinite impedance.
That gives me a fairly horizontal load line.

Not necessarily - the next stage always presents some kind of load. Consider not only the Miller capacitance but also the Input impedance of the next stage. This will vary dramatically depending on the type of circuit (ie very high for cathode followers but extremely low for grounded grid) and also the type of tube. One tube I'm using has an input impedance of only 4k or so in CCS! Therefore the load line MAYBE far from horizontal even with a plate choke.

>Now who said "high levels" - not me.
EL84s are known for their sound but
many have found them too syruppy which
I suspect is too much 2nd harmonics.
Now to get back to my original question 8^(
Does a "horizontal" load line reduce
the 2nd harmonics distortion?

Yes it does but the amount of reduction can vary from minute to very significant depending on the tube, chosen operating point, magnitude of the signal and obviously slope of load line.

Also, in your original post you equated 2ndH to sweetness. Agreed the amount is subjective and I drew a quantitive conclusion. But what I was saying is that I disagree with that ... in I'm fact diametrically opposed!

>Leaving aside if:
sweetness does/doesn't equal 2nd H levels
I can/can't get a horizontal load line

Not sure what you mean here but I think you are asking whether you can achieve a horizontal load line in reality. Damn close but not quite. It's always going to come down to the ratio of TOTAL load presented to the tube compared to it's own internal rp. Since this can never be infinite there will always be some slope but it could be essentially horizontal.

This happens on AA, not just you,
everyone gets on their soapbox to profess
their "truth" and don't answer the question.
Maybe nobody knows the answer - I don't know -
but it's frustrating sometimes.
Now I'LL get off my SOAPBOX 8^D

Ah Dan, I'm glad you brought this one up. Whilst I tend to agree (me included), what really frustrates me even more is when postings are so unclear you have to second guess their true meaning ... so much for modern shorthand! Now this happens way more often and is often a major contributor to answers that don't address the INTENDED question. It goes the other way as well.

While I'm at it (and this is NOT aimed at you), I also hate smart ass answers to genuine questions, especially from newbies and non technical inmates, who are just trying to get some help.

That's my real sermon for the day!

Cheers Dan,
Naz

This post is made possible by the generous support of people like you and our sponsors:

Kimber Kable

---

[ Top of Page ] [ Contact Us ] [ Support/Wish List ] [ Copyright © 2025, Audio Asylum, all rights reserved ]

---

[ General ] [ Speakers ] [ Tubes ] [ Vinyl ] [ Digital ] [ Hi-Rez ] [ Video Asylum ] [ Cables ] [ Tweaks/DIY ] [ Music ] [ Films ]

---