looking for bass treble pcb pattern

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#2
ataul said:
Hi friends

I like to make a pre amp with bass treble control, I want PCB pattern for bass treble circuit, please help to find or any link for this.
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I don't know of any ready made PC boards that you can simply buy - at least none worth their salt.

I recently completed my own preamp and made my own boards using ExpressPCB and their free software to make these:

An externally hosted image should be here but it was not working when we last tested it.


The circuit is based on this. Note that I did not populate resistors R11 & R12 and by-passed the first stage of the 12AU7 tube. The reason was that I did not need the gain, so pins 1, 2 & 3 remained unconnected and resistor R1 is mounted in the upper position to do that.

Here is the schematic. The actual tone control components are mounted to the pots. The circuit has limited boost/cut of about ±9 dB.

Distortion is well below audible at about 0.01% @ 1 kHz. I plan to get formal distortion numbers in a few days when I visit my friend's lab.

An externally hosted image should be here but it was not working when we last tested it.


If you want to make your own PC board using ExpressPCB, it cost me $110 for three boards. Each board is a single channel.

The boards are 2.5" by 3.8" double layer glass boards.

The cheapest way to do this is point to point wiring, but if you want PCBs you either pay a board house or you can etch your own.

Lastly, the heaters are wired directly by a 12 VDC supply to the + and - pads on the board. One of the boards has a wire from one of the pads labeled C to a resistor network, which is connected to the +250 VDC supply. This elevates the heater supply to about 80 VDC.
 
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#4
ataul said:
thanks for reply
I prefer for IC based tone control pcb lay out. Tube based audio is the best but i have no experience about tube circuit.
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Check out Rod Elliot's website projects. He has some excellent solid state designs and he also sells PC boards.

Rod Elliot's Project 97

I built my own version of Project 97 and it is excellent.

An externally hosted image should be here but it was not working when we last tested it.


In the end I used different chips than the TL072 amps (LM4562), which are a much higher speed chip. I had to add a 20 pF cap between pins 6 and 7 to stop a high frequency oscillation.

Pots were 100K linear pots.

My board was a mix of surface mount and through hole components and I mounted the pots directly to the board in a different configuration (Board lays on the back of the bass & treble pots). My layout size is .9" by 2.5" for one channel. Surface mounting components takes some skill, so it may not be your cup of tea.

Regardless, the end result was excellent after some help from some members here to wring out some bugs.

An externally hosted image should be here but it was not working when we last tested it.
 
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