Audio pre amplifier & tone control (bass-high), a classical circuit of the 1970s demo & schematic

Описание: Please read the textbox first for more information. Correction: potentiometer in the emitter lead of the second transistor is (also) 1K (= 1000 Ohm).

Video of a classical tone control, made with two 100 K potentiometers (bass-high audio control) combined with a few capacitors (3N3 and 68 N) to control the audio range between say 50 Hertz and (say) 16 KiloHertz.

The circuit was published in my book “Audio Amplifiers and Loudspeaker boxes”, on the LULU website, on page 70.

You can find/buy this book, when you go to the LULU website and search on my name, author Ko Tilman. But that is not very important, because I publish it now on YouTube, anyway.

By the way: that earlier audio bass-boost pre amp is here:Video link
   • Audio pre amplifier with mellow sound and ...  

The audio end-amp that I use in this video (working on say 35-40 V) is here Video link
   • The 25 - 40 Volt audio amplifier, giving o...  

Please note: many other audio amps are usable (read the description), also in the 12 V-18 Volt range, giving out say 5-8 Watts.

The audio filter unit in this video now (29 aug 2023) is situated in-between two BC 547 b audio amplifier transistor stages, of which both (2 times) the amplification and (thus) the sound color can be aligned/set via the 1 K potentiometers in their emitter leads (both emitter leads of the BC 547’s).

Of course the setting of the tone control potentiometers (both 100 K) in the audio filter itself, in-between these two transistor stages, also plays an important (!) role in the sound that you will hear.

It all (better said: also) depends on the input-output impedance and how the second audio amplifier “picks up” the sound and amplifies it.

Bias of the 2 transistor stages is set via the 27 K-10 K resistors (schematic).

It is a “standard” bias for 9 V-18 V and a NPN Silicium transistor. Thus it gives out proper & undistorted audio signals, by using the 27 K and the 10 K resistor(s) (to the bases of the transistor (s).

I made this circuit, by purpose, with the two 1K potentiometers in the emitter leads (with these 10 uF electrolytic caps from the wipers to ground, minus, -) because the alignment of these 1K potentiometers play an important role in how the audio sound “sounds”.

Say, thus, apart from the filter unit, where also the sound character (bass-high) is set via the two 100 K potentiometers, in combination with the used capacitors (more info the schematic).

Please: try, experiment, change especially the capacitor values in this audio filter (around the two 100 K potentiometers) to get to completely other audio sound results. So that you want/need/find useful good sound profiles in a certain audio application, in situations where that sound has to be reproduced. Say a living room, a ball room, a big room, a stage, a church, or whatever where.

A usable audio amplifier is here:    • The 25 - 40 Volt audio amplifier, giving o...  

But perhaps even more usable classical audio amp is here:
   • Audio amplifier 5-10 Watt with the TDA 200...  
Made with a Philps “TDA” Chip

Or, when you want it with an Opamp, driving end-transistors:
   • Good quality 2-3 Watt audio amplifier with...  

Or, again, with a Philips Hi Fi Audio chip:
   • The TDA 2615: a beautiful 2 x 6 Watt Hi Fi...  

Or, completely classical, with say the 2N3055 etc (good sound by the way & very useful and simple):

   • Nice sounding 5 Watt audio amplifier with ...  

Of course you can also use “Ali” audio amps (chips), sometimes they are kind of class “D” amplifiers, and/or/thus digitally amplifying an analog audio signal, say sending it into an AD converter, amplifying it digitally (easy) to an enormous output level into a low Ohm load, say a loudspeaker, thus via converting it back to analog DC (audio) out. I don’t have experiences with these AD-DA setups, so I cannot advice something in that “field”.

My You Tube channel trailer is here:    • Radiofun232 on YouTube, find working & tes...   When you search, search always “NEWEST FIRST” to get the right overview.

You can also search via the “looking glass” on my Channel trailer via keywords like ”audio”, “radio”, “amplifier”, “filter”, “Shortwave”, “transistor”, “FET”, “oscillator”, “generator”, “switch”, “schmitt trigger” etc; so the electronic subject you are interested in.

My books about electronics & analog radio technology are available via the website of "LULU”, search for author “Ko Tilman” there.

https://www.lulu.com/search?adult_aud... I keep all my YT videos constant actual, so the original video’s with the most recent information are always on YouTube.

Search there, and avoid my circuits that are republished, re-arranged, re-edited on other websites, giving not probable re-wiring, etc. Some persons try to find gold via my circuits. I take distance from all these fake claims. I cannot help that these things happen. Upload 29 Augustus 2023.

Music: Johan Sebastian Bach, “Liebster Jesu wir sind hier”
And: “In Albany, New York” from the 127 ers
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