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I am one of these guys that doesn't see tone controls and global and nested feedback as being evil when properly executed. My original audio mentor always told me you want the most minimal electrical pathway to achieve the flattest response.One day I asked Kenny,is your room flat? Are your speakers perfectly flat? Is the listening material flat and the final question was,is our hearing perfectly flat? When the answer to all my questions was unequivocally no,my next question was,what's the big deal about having tone controls then? The answer is they cause phase shifts at various frequencies.
What your better audio companies like HK,Marantz,and Mac's later C22 did was to use tonal switching.I kind of preferred what Stu Hegeman did with the Cit 1 because he used the lower MU 12AT7s over the 12AX7s because the extra gain wasn't really needed being he used four triode stages in the line stage per channel and the tone switching didn't really need extra gain because it basically inserts a different R/C combo when you switch position for more treble or bass or less treble or bass.You are really only using one combo at a time per position on each switch.
The 7C unlike the C22 and Cit 1 puts its R/C cap combos in series with each other where HK and Mcintosh used the cap as a bypass.I'm still asking myself why Marantz didn't execute the bypass method as it seems like the signal would less prone to phase shift going thru a resistor as opposed to going thru a small ceramic cap and then thru the resistor unless I'm missing something?
A friend you get for nothing,an enemy has to be bought
Edits: 05/14/16 05/14/16Follow Ups:
Equipment manufactures MUST sell new products in order to stay in business. Magazines and (much later) websites must review the latest gear in order to retain subscribers so they can remain in business. Reviewers must write flowery prose about this new equipment in order to pique the interest of their readers and increase circulation in order to retain their jobs.
So along came the 1970's. Not a whole hell of a lot of really new gear hitting the marketplace. The manufacturers (and the rest) realize that they have to come up with something in order to stir up consumer interest and convince their target audience to give up their old stuff and buy the "new, improved" versions. All of a sudden, tone controls are the spawn of the devil (the straight wire with gain argument), tubes introduce distortion (and have become obsolete) and cartridges must track at .5g to .75g in order to qualify as the current "state of the art" so consumers are lectured that they must toss their old cartridges and buy tonearms that are able to handle this ultra-low tracking force in order to retain their membership in the state of the art club.
So, tone controls are slowly coming back in vogue, tubes are seeing a strong resurgence in the marketplace, and where can one find a new cartridge (or tonearm for that matter) that is capable of performing at .5g?
It's all about sales, people.
My admittedly jaded opinion leads me to say "follow the money"!
Let's not forget one more aspect here. As an audiophile and recording engineer, I may EQ a singer on the way to the recorder. Then, during mixdown, more EQ may be added going to the Master. Then once the Master goes out for Mastering", a final EQ change made be made as well. So by the time you buy the music, the phase shifts are already there. Therefore, a little extra EQ at home doesn't make much difference in the whole scheme of things.
One day I asked Kenny,is your room flat? Are your speakers perfectly flat? Is the listening material flat and the final question was,is our hearing perfectly flat?
Unfortunately, tone controls with single hinge frequencies and broad slopes are incapable of correcting any of those variations. For the music system where I have performed measurements, they would be ineffective.
I do, however, use precise parametric EQ attenuation at a couple of regions to tame modes in the HT room.
Unfortunately, tone controls with single hinge frequencies and broad slopes are incapable of correcting any of those variations. For the music system where I have performed measurements, they would be ineffective.
I agree with you.When I made the post,I'm speaking to those that don't have the most ideal conditions as far as room acoustics and slopes in part of their speakers at certain frequencies,adding a bit of tonal EQ can sometimes compensate for conditions that aren't do ideal.
A friend you get for nothing,an enemy has to be bought
"what's the big deal about having tone controls then? The answer is they cause phase shifts"
I'm a fan of tone controls, they can indeed be very useful at times. Nevertheless, I don't agree with the above conclusion. Whenever feedback-based tone controls are introduced into a circuit, sonics become modified by both the additional coupling caps and the transient distortion created by feedback. The latter, in particular, is IMO one of the great contributors to the degradation that occurs when one moves from a short-path, all triode amplifier to pentodes. If a circuit as complex as the one posted here does not cause a loss of nuance and smearing of details when inserted into a system, the system needs improvement.
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Buy Chinese. Bury freedom.
Whenever feedback-based tone controls are introduced into a circuit, sonics become modified by both the additional coupling caps and the transient distortion created by feedback.I should have been more specific but in the case of tonal switching circuits,the nested loop FB is going to be in the gain stage itself,and not in the tonal R/C combo..Notice the signal has already passed thru the R/C components without being touched and is now on its way to the gain stage.This is why so many people prefer passive rather than active tone controls I would guess.. There are passive tone control circuits as well but you are still dealing with some phase shift issues by nature of a potentiometer.
A friend you get for nothing,an enemy has to be bought
Edits: 05/15/16
Until all recordings are uniform and perfect...
Goes against the principle of simple circuits and "straight wire with gain."
Equalization is a good "bandaid" for lesser systems, recordings, and bad acoustics. Years ago I used 16-band equalizers to fix vinyl recordings, speakers, and rooms.
Today my listening room is measured and acoustically tuned. My system is tri-amplified using tube and solid state amps and the speakers employ high efficiency flat range drivers with simple 6 dB crossovers. No tone controls needed. Sounds much better.
Equalization is a good "bandaid" for lesser systems, recordings, and bad acoustics.Exactly what it is there for because most don't have the most ideal conditions,especially those living in small apartment listening to poorly recorded vinyl or CDS from the early days.
A friend you get for nothing,an enemy has to be bought
Edits: 05/16/16
Mike, what pre-amp is this? Very interesting setup for the tube heaters. Are the heater legs, after the 1500mfd cap, supplying (+) 6.3VDC and (-) 6.3VDC?
Why are V1 and V2 grounded at pin 4? Yet, V3 and V4 are not?
Thanks!
Excellent preamp.
A friend you get for nothing,an enemy has to be bought
I can't comment on the electronics of tone control, but I have multiple sets of speakers in the same general area that can be connected to a multitude of different amps (all tube at this moment, and all different types of power tubes) in a less than ideal setup in very imperfect listening area with aging ears. Even relatively minor changes in volume can produce drastically different response in my systems.
I want things to sound "good" to me, and I really don't care about anyone else's opinion when I listen to music by myself (which is 99% of the time). If I could not play with the tone controls on my preamp (which is a McIntosh SS), then I probably would not enjoy listening very much.
While I do have various tubes I prefer in my amps over others (both input and power), it is usually not because of the sound profile (I tend not to hear all the level of difference that people spend countless hours discussing on this forum and others).
For me, it is tone controls that allow me to adjust everything to what I want to listen to at that particular moment.
I want things to sound "good" to me, and I really don't care about anyone else's opinion ....
Boy that sure makes sense to me. I don't GAS what others think either. If someone wants to cough up some cash, I'll make the "improvements". Better yet, just give me the cash. I don't chase my tail.
"I can't compete with the dead" (Buck W. 2010)
"It would take me forever. I don't think I have forever" (Byrd 2015)
and hifalutin remarks about using some of your system as a "tone control" . A good example is ones preferences regarding cable.
I bought some really nice Cardas Golden Reference ICs a while back, for the way music sounded through them. They made my whole system sound better to me. Don't even get me started about employing certain tubes for improving the sound either. Come to think of it a lot of tube provide some control over tone.
What's this forum about- in part anyway??
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