Unfortunately this URL is death.
Thank you for this URL.
I am looking for comercial available high quality preamplifiers and integrated amplifiers include such a tone control unit.
Which brands are here a good choice?
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Similar topic - other thread:
http://www.diyaudio.com/forums/solid-state/21307-looking-very-good-tone-control-schem.html
http://www.diyaudio.com/forums/solid-state/21307-looking-very-good-tone-control-schem.html
I was interested in making a tone control for my amplifier project. The Baxandall filter looked attractive for its ease and passiveness. I just analyzed the phase response of the Baxandall tone control with source impedance of 500 ohms. There is noticeable phase shifts in the high and low frequencies at various pot settings. Did I do something wrong or is this inherent in this design?
excuse me my bad english - the correct term is of course "most ultimate" and not "Ultimatest"
Many thanks to the moderators for changing the headline for topic (for better finding at a later time).
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an alternative toncontrol solution to Baxandall's approach:
http://www.diyaudio.com/forums/solid-state/44834-quad-44-preamp.html#post3355215
For a special application I want to create on half of Baxandall's approach - those half for treble boost. Therefore I have found follow proposal:
Treble boost - found under fig. 4 by
http://www.angelfire.com/electronic/funwithtubes/Amp-Tone.html#Amp-Tone-Primitive-4-back
and attachment here.
Theory of operation (quotation from mentioned URL):
On the left is an input terminal which connects to the grid of a triode, 12AX7.
The grid goes to ground through a 470 k ohm resistor.
The cathode goes to ground through a 1.8 k ohm resistor.
The plate goes to B plus two through a 100 k ohm resistor.
The plate also connects to one end of a 0.1 microfarad capacitor.
The other end goes to the top of a 500 k ohm pot.
The bottom end goes to a point labeled output.
The output point goes through a 47 k ohm resistor to ground.
The wiper of the pot goes through a 330 pf capacitor to the top of the pot.
This one gives about 14 dB of boost.
Oddly enough it requires a linear pot rather than the audio taper of the other circuits.
Also as shown the pot will work backward unless it is reverse wired.
The capacitor can be connected from the wiper to the output terminal without any change in performance.
That makes the pot work forward.
I will reduce resistors and enhance capacitors by factor 100, because the previous driver stage can deliver 1A output current. Instead the potentiometer I will use an ELNA rotary switch. Additional rotary switch I will use for variation the lower cut-off frequency (determining of the frequency, from those I want to get treble boost).
Maybe someone has an idea of what one can take also into account like the variation of the degree of slope etc.
Thank you for advices.
http://www.diyaudio.com/forums/solid-state/44834-quad-44-preamp.html#post3355215
For a special application I want to create on half of Baxandall's approach - those half for treble boost. Therefore I have found follow proposal:
Treble boost - found under fig. 4 by
http://www.angelfire.com/electronic/funwithtubes/Amp-Tone.html#Amp-Tone-Primitive-4-back
and attachment here.
Theory of operation (quotation from mentioned URL):
On the left is an input terminal which connects to the grid of a triode, 12AX7.
The grid goes to ground through a 470 k ohm resistor.
The cathode goes to ground through a 1.8 k ohm resistor.
The plate goes to B plus two through a 100 k ohm resistor.
The plate also connects to one end of a 0.1 microfarad capacitor.
The other end goes to the top of a 500 k ohm pot.
The bottom end goes to a point labeled output.
The output point goes through a 47 k ohm resistor to ground.
The wiper of the pot goes through a 330 pf capacitor to the top of the pot.
This one gives about 14 dB of boost.
Oddly enough it requires a linear pot rather than the audio taper of the other circuits.
Also as shown the pot will work backward unless it is reverse wired.
The capacitor can be connected from the wiper to the output terminal without any change in performance.
That makes the pot work forward.
I will reduce resistors and enhance capacitors by factor 100, because the previous driver stage can deliver 1A output current. Instead the potentiometer I will use an ELNA rotary switch. Additional rotary switch I will use for variation the lower cut-off frequency (determining of the frequency, from those I want to get treble boost).
Maybe someone has an idea of what one can take also into account like the variation of the degree of slope etc.
Thank you for advices.
Attachments
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I suppose even within the best Baxandall design there will be some 'inaccurate' phase and frequency behaviour
what else is to be expected from a filter ?
I plan to use it as integrated part of active xo
This I know. But most important to know is the fact, that audible effects rises up by the phase and frequency behaviour of the whole audio system for the reproduction and the whole recording system (created at a previous step).
This means, all exist kinds of tone control/equalizer topologies provides not in all cases disadvantages by listening tests.
I try to help with my treble boost a guy, which had losses the high-frequency hearing in a for me unknown kind.
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My english is in general not the best and particularly concerning hearing aid stuff very very bad.
I don't understand also this:
"medicine with sideeffects"
The aim is indeed to compensate the unwanted owner's ear/brain low pass function - according the graph from user's consultant.
Successes in this matter I doubt very much - but I want to test it nevertheless.
According to my observations over the years only the following causes for this undesired effect (i.e. the sound deterioration) come into question:
1) with extra gain stage for bass-treble unit:
- additional sound signature due integrated or discrete operational amp stages
2) without extra gain stage for bass-treble unit (i. e. network for bass-treble unit in the NFB loop of power amplifier):
- not unity-gain stable and thus sometimes unwanted superimposed RF oscillation
Independent of this ordinary cheap parts concerning high impedance bass/treble potentiometer and small sized polyester capacitors makes sound character muddy, which is often clearly noticeable when the tone defeat switch is pressed. Effects by phase shift are inaudible because slope is max. 6db/oct. - so I think (minimum phase character).
Only the use of a low-impedance NFB network for the tone control unit with ELMA 04 rotary switches and high-quality KP capacitors in combination with a unity-gain stable power amplifier avoids the audible disadvantages of tone control.
P.S.: in post #1 I have updatet some URL's
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What find annoying is that very few baxandall active designs considered to have at least a small overall gain for the op amps then they complain of phase shift, poor psrr, cmrr unless they use very expensive op-amps...Way too many active Baxandalls wired for unity gain...
If you're into discretes you'll hardly find anything better than this:
http://www.hifi-classic.net/review/realistic-sta-2250-262.html
If you're into discretes you'll hardly find anything better than this:
http://www.hifi-classic.net/review/realistic-sta-2250-262.html
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The Quad 33 is one such, although executed with discrete components. Gain of 5 around the Baxandall stage.
But I take exception to the title of this thread, which contains two internal contradictions. There is no such thing as a passive Baxandall tone control, and the so-called 'James-Baxandall' topology is a fiction.
But I take exception to the title of this thread, which contains two internal contradictions. There is no such thing as a passive Baxandall tone control, and the so-called 'James-Baxandall' topology is a fiction.
the terms "active" and "passive" often define different meanings.
An active speaker box e. g. can mean that the power amp is integrated in the speaker enclosure.
But for me an active speaker means
1) the filter stage is located in front of the power amplifier stage and
2) the filter components are arranged as a positive feedback (Sallen-Key) or negative feedback (MFB) network around an operational amplifier stage.
Even in cases, where this unit operates as outdoor unit.
But maybe I am wrong even on this.
In case of this Baxandall tone control network for me "passive mode" means, this network operates between two linear gain stages and "active mode" means, the network operates in the NFB network of a gain stage - sometimes even the gain stage is the power amp itself (like Luxman L550).
What is from your view the right naming of topology for tone control unit as mentioned here ?
https://audiohertz-com.translate.go...tr_sl=en&_x_tr_tl=de&_x_tr_hl=de&_x_tr_pto=sc
'Active' means there is a necessary active gain element. 'Passive' means there isn't. Active is different from passive, but neither of them individually can mean different things.
See above. QED. I don't know what else it could mean, but I'm open to suggestion.
No. That would be a passive speaker using an active crossover before the amplifier. It doesn't have to use PF or a Sallen-Key topology to satisfy that criterion. The speaker itself is two stages away from being active.
Sure. That makes the Baxandall stage active, and the James network passive, and the so-called 'James-Baxandall topology' a meaningless fiction. It comes from one term paper by an undergraduate in South America that should have been taken down years ago.
He is talking about the Baxandall, active, tone control. No mystery.
Interesting. Completely new to me. Until now I assumed that Peter James Baxandall was the inventor of this kind of tone control. Has this already been discussed in detail here?
Independent of this, the words for "active" and "passive" are almost identical in German and English, but colloquially in both languages - partly depending on the context - sometimes different.
In English for me is a loudspeaker with integrated power amp a so called "Powered Box" - independent of the used kind of crossover network.