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Hi!
What is the opinion nowadays on using the original tone control by Baxandall, as published Wireless World 1952? Is it still worth incorporating in a diy hifi preamp, or are there better circuits? (Link below

http://hifisonix.com/wordpress/wp-co...edbackTone.pdf

He states in the article that it works best with a high gain tube like a pentode (EF86?). I would rather use 12AT7 and put a 5687 as a cathode follower after it. I tried simulating his circuit in ltspice but got questionable frequency response, not sure if it was my doing or the tube modeling that was lacking.

Martin

[Phil Allison[_3_]]

What is the opinion nowadays on using the original tone control by
Baxandall, as published Wireless World 1952? Is it still worth incorporating
in a diy hifi preamp,


** Every hi-fi pre-amp needs a "tone control " just like every fish needs a
bicycle.


or are there better circuits? (Link below

http://hifisonix.com/wordpress/wp-co...edbackTone.pdf

** Every hi-fi pre-amp needs a "tone control " just like every fish needs a
bicycle.


He states in the article that it works best with a high gain tube like a
pentode (EF86?).

** Using the present tense like that when the remark was made * 62 years ago
* is a tad ridiculous.


I would rather use 12AT7 and put a 5687 as a cathode follower after it.

** No need exists to use anything .

Any CD/DVD player will drive a valve power amp to full output via a passive
attenuator.

Even a Quad II.


I tried simulating his circuit in ltspice but got questionable frequency
response,
not sure if it was my doing or the tube modeling that was lacking.

** Really ??

Got no toy trains left to play with ??



..... Phil

[[email protected]]

Phil Allison wrote:

** Every hi-fi pre-amp needs a "tone control " just like every fish needs a

bicycle.


Actually, I have avoided tone controls in the signal path for years. Until I realized that it is fun to have one. But one that can be switched out of the signal chain. When I started looking for typical circuits, most of them turned out to be some kind of variant of Peter Baxandall's. Question was, is it *good* in a modern tube context (with many digital sources) 2014?


Got no toy trains left to play with ??

Touché! Hahaha.

Martin

[[email protected]]

Not so many responses, hmm. Perhaps people are on vacation. Or maybe I should be more clear.

If one wants a 2-band tone control that can enhance treble and bass response on some recordings - what type of circuit is generally thought of as best, i.e. creating minimal distorsion or other problems in a tube context? I have found two basic solutions from the tube era, but until I build them I an unsure what works best.

Most TC circuits I have studied are meant for guitar amps, where coloration and distortion is something wished. Purist high end preamps seem to be made without tone controls, which I am recently starting to find a bit silly - however pure the signal path is, the esoteric builder is still voicing the amp by choosing component brands and operating points of the tubes so why not give more control to the listener. (PIO vs. teflon caps anyone?) So that is why I want to learn about tone controls.

Baxandall works in the feedback loop, and the earlier E. J. James version although similar looking is inserted as a passive circuit between two stages.. Both use up some of the gain. There is also the question of which circuit is easiest to bypass with a simple switch. I am thinking that a Baxandall can be replaced by a resistor of equal value to the TC network, to maintain the feedback and signal level on the output. Or does anyone have a better idea?

A simple loudness switch would also be interesting, something that can boost the top and bottom a bit. I know it is not the purist approach, but, hey, its meant to be a fun hobby

Link to James's 1949 paper: http://www.thermionic.info/james/Jam...oneControl.pdf

Martin

[John L Stewart]

Originally Posted by

Not so many responses, hmm. Perhaps people are on vacation. Or maybe I should be more clear.

If one wants a 2-band tone control that can enhance treble and bass response on some recordings - what type of circuit is generally thought of as best, i.e. creating minimal distorsion or other problems in a tube context? I have found two basic solutions from the tube era, but until I build them I an unsure what works best.

Most TC circuits I have studied are meant for guitar amps, where coloration and distortion is something wished. Purist high end preamps seem to be made without tone controls, which I am recently starting to find a bit silly - however pure the signal path is, the esoteric builder is still voicing the amp by choosing component brands and operating points of the tubes so why not give more control to the listener. (PIO vs. teflon caps anyone?) So that is why I want to learn about tone controls.

Baxandall works in the feedback loop, and the earlier E. J. James version although similar looking is inserted as a passive circuit between two stages.. Both use up some of the gain. There is also the question of which circuit is easiest to bypass with a simple switch. I am thinking that a Baxandall can be replaced by a resistor of equal value to the TC network, to maintain the feedback and signal level on the output. Or does anyone have a better idea?

A simple loudness switch would also be interesting, something that can boost the top and bottom a bit. I know it is not the purist approach, but, hey, its meant to be a fun hobby

Link to James's 1949 paper: http://www.thermionic.info/james/Jam...oneControl.pdf

Martin

Over the years I've used both the losser & Baxandall ccts. For me either way is OK but that is a subjective decision. My preference from a cct point of view is the Baxheers, John Stewartandall since some NFB is used to help keep a lid on distortion.

And you are correct, it is a fun hobby! This forum used to be a lot busier. But after many old men had dissagreements about nothing most folks left for quieter places!

C

[Lord Valve]

Phil Allison wrote:



What is the opinion nowadays on using the original tone control by
Baxandall, as published Wireless World 1952? Is it still worth incorporating
in a diy hifi preamp,

** Every hi-fi pre-amp needs a "tone control " just like every fish needs a
bicycle.

or are there better circuits? (Link below

http://hifisonix.com/wordpress/wp-co...edbackTone.pdf

** Every hi-fi pre-amp needs a "tone control " just like every fish needs a
bicycle.

He states in the article that it works best with a high gain tube like a
pentode (EF86?).

** Using the present tense like that when the remark was made * 62 years ago
* is a tad ridiculous.


...

Actually, it's OK within the sentence structure the OP chose,
"he states." It would have been more appropriate if he had
said "he stated," true, but his choice isn't incorrect. The phrase
""In the article..." is implied by his use of "he states." Of course,
English may be different in Oz... ;-)


I would rather use 12AT7 and put a 5687 as a cathode follower after it.

** No need exists to use anything .

Any CD/DVD player will drive a valve power amp to full output via a passive
attenuator.

Even a Quad II.

I tried simulating his circuit in ltspice but got questionable frequency
response,
not sure if it was my doing or the tube modeling that was lacking.

** Really ??

Got no toy trains left to play with ??

.... Phil

....

Hey, Phil - don't be such a ****. Maybe he's building a guitar
amp. Some of us do, y'know.

[[email protected]]

Lord Valve wrote:

Maybe he's building a guitar amp. Some of us do, y'know.

I have repaired a lot of them, but never built a serious one from scratch. Damn, how guitar guys smash up their gear!

Martin