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| Bass Guitar Amplifier Build - help and guide. |
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| Pexy13:
Greetings. Since I recently started playing bass guitar I decidet to build my own amp insted of buying one. After searching the web for an appropriate schematic I found a page created by Dr. Bora Jagodić. (http://bas.elitesecurity.org/indexV.html) In it I found a schematic for a bass guitar amp and it seems perfect for my needs. For the power amp I decided to go with a TDA7294 as he sugested to use. I'll also build a 15V preamp PSU and a 22V power amp PSU. The schematic includes a ALC(automatic level controll) circuit that prevents clipping. It is optional but i would like to include it. But for more diversity can I include a switch that will connect and disconect the ALC circuit. I was thinking of inserting it before the drain of a 2SK30 fet and after the output of the power amp. Am I going to be able to achive what I intended or is there something different that I need to do to achive that? I will also insert a PDF with schematic and a Target 3001 file where I desinged the whole Amp. Thanks. Sven. |
| Zero999:
The symbol on your schematic is for a MOSFET, but the one on the PDF drawing is a J-FET. On your schematic, the drain is connected directly to the output of the op-amp which is wrong because the op-amp could go into current limiting mode, which would result in distortion. It should be connected to the other side of th 15k resistor, as per the PDF drawing. A switch in series with the drain would disable the AGC circuit, when it's open. |
| SiliconWizard:
Adding to the above, I'm personally not too keen on the original schematic's volume control arrangement. |
| 2N3055:
--- Quote from: SiliconWizard on April 04, 2019, 03:26:22 pm ---Adding to the above, I'm personally not too keen on the original schematic's volume control arrangement. --- End quote --- That is actually quite common preamp gain control circuit. Master volume control would come before power amp. |
| Pexy13:
Yeah, I conected the switch to the wrong side of the 15k resistor by accident. I will then use a single SPST switch in series with the drain. I don't know why in the pdf the symbol is for a J-FET when the 2SK30 is a MOSFET. Thanks. |
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