Wilki1 said: Each tone section consists of resistors and capacitors to determine the frequency. The associated pots determine the boost or cut of each band. There is no adjustment for Q on each band. In Archived forum
And I would like to know the determined frequencies for bass, mid and treble to have a better understanding of what I’m doing 🙂
Is it possible to know it? without to build it and use a spectrum analyser? Or calculate it with resistors an capacitors?
Since you are native French speaking I would suggest Google using the words Baxandall EQ as there is a ton of information out there (perhaps in French) and this would allow you to learn everything you would wish to learn and more if you like.
A Baxandall tone stack is a high/low shelf EQ. Versions can be found in Ampeg, Orange, Tweed Fenders, Sunn amps and more. With the controls set to 12:00, the frequency response is essentially flat, as opposed to a std TMB tonestack, which has a mid-scoop and bass roll-off with the controls set the same. A Bax stack is capable of essentially a mid-hump, which a std stack is unable to accomplish at any setting.
This circuit has been used in every stereo system since the 70’s for good reason and as a result there is plenty of information readily available. Also here is a link to a great Tone Stack Calculator.
The toneTwEQ circuit consists of 3 filters. The Treble and Bass filters are shelving type filters that boost or cut frequencies using a 1Khz midpoint. The Mid filter uses a center frequency of 1KhZ to boost or cut. The amount of boost and cut is about 15dB. Here is a diagram of the frequency response: