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Old 4th December 2010, 04:13 AM   #1
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Default Tube mixer

I'm projecting a 10 Ch mixer tube, with an IC output section for 4 monitors (...where a high quality of the signalit is not necessary).

1) I'd like to know if the outputs IC sections (for the monitors) may affect the signal after the tone control section.

2) Somebody can help to answer to the questions reported into the IC section?

Many anticipated thanks
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Old 4th December 2010, 04:25 AM   #2
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Default ... a better image of the schematic

Sorry ... I enclosed a better image of the schematic.
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Old 4th December 2010, 10:01 AM   #3
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Hi Antonio,

I think the first thing you need to look at is the tone control stage because I think with the values shown it will present too heavy a load to the tube stage driving it. This will cause much more distortion than any loading effects the later IC stage might cause.

Cheers

Ian
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Old 4th December 2010, 11:48 AM   #4
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The White cathode follower should be able to deal with the tone controls. My question is, why so much gain? The way you have it set up, gain is about 250. That seems... excessive. The input cap for the tone controls is not necessary if the preamps have output capacitors. The internal coupling caps can be 2-10uF. R1 can be large- 100k will work fine (not critical). R5 can be 10k (not critical). R4 is superfluous.
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Old 4th December 2010, 05:59 PM   #5
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Quote:
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The White cathode follower should be able to deal with the tone controls.
I see no White follower, just a regular CF with a CC load. Either way, the tone controls with the values shown will look like a 2K load at mid frequencies which will definitely lead to increased distortion.

Cheers

Ian
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Old 4th December 2010, 06:54 PM   #6
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I don't use tone controls in my tube mixer: today tube mixers are too expensive to be used with crappy dynamic mikes that need individual equalization.
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Old 4th December 2010, 07:29 PM   #7
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I don't use tone controls in my tube mixer: today tube mixers are too expensive to be used with crappy dynamic mikes that need individual equalization.
But, of course, that is NOT what EQ is for.

Cheers

Ian
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Old 4th December 2010, 07:32 PM   #8
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But, of course, that is NOT what EQ is for.
Can you enlighten me please, what for are Baxandall shelf-type EQs in each channel strip then?
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Old 4th December 2010, 09:04 PM   #9
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Can you enlighten me please, what for are Baxandall shelf-type EQs in each channel strip then?
Well a Baxandall HF/LF EQ is clearly quite simple and therefore limited but it does have its uses.

Often when mixing, it is important to manage the audio spectrum. In particular, to avoid muddying the bass (guitar or synth etc) it is common practice to roll off the bass end of all other instruments (guitars, snare drums etc). In other cases bass roll off is used to achieve a particular sound e.g to make a thin sounding rythm guitar.

Equally, to add sparkle, it is common to add some HF boost to individual instruments.

Cheers

Ian
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Old 4th December 2010, 09:18 PM   #10
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All instrumental amps have own tone controls, so even when miking cabs I don't see any reason to have Baxandall controls in channel strips. I've found that the better are mikes and mike preamps, the less audio engineers want any EQ in them. Do you read Gearslutz forum, Ian?
Insert sockets would be much more valuable, according to my experience.
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