| DC Dave |
I'd like to use this thread to document my 6 channel pre project.
After building a few chipamps I decided its time to build a preamp. There are a few features I want to incorporate into the design.
First it must be an active design. I'm thinking maybe going with a AD815 or OPA2132 design for the gain stage. I don't have 6 OPA627s, otherwise I might use those.
I need a headphone amplifier, must likely a 2132/BUF634 combo. I built one with that combo and am happy with it.
It needs to be able to switch between three sources.
I'm thinking about having a subwoofer crossover and output built into the main channels.
The basis for this project is a Yamaha MVS-1 Master Volume Control I bought from the local Goodwill store for $15. It has a nice 6 channel pot and three input selector. It will switch between two 2 channel sources and one 6 channel source, and also has Tape inputs and outputs. It is a purely passive device with lots of room in the case. I figure I will reverse engineer it to make it an active pre and add the headphone amp and sub crossover. I might also add a NOS DAC and USB input.
I don't really need 6 channels, but I don't want to waste the 6 channel Alps pot, and I might get into multi channel audio later. |
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| Russ White |
Sound like a fun project! :)
If you liked the 2132 and the BUF634, I wonder if you might like the 627/634 combo even better for the headphone amp. :) |
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| DC Dave |
| Here is a pic of the insides. I have one of the PE $5 buyout toroidal trannys that will fit in the corner easily. I might get rid of the stock PCB and just keep the selector switch part of the board. The RCA connectors are **** and will be replaced. Seems like it should be pretty straight forward. |
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| DC Dave |
| quote: | Originally posted by Russ White
Sound like a fun project! :)
If you liked the 2132 and the BUF634, I wonder if you might like the 627/634 combo even better for the headphone amp. :) |
I have a couple of the 627s in my parts box and will most likely try them out. |
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| cowanrg |
| wow, its crowded in there! |
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| DC Dave |
| This is the sub crossover I want to incorporate. I want it to be part of the 2 channel inputs. Should it be placed after the gain stage (after the OPA2132 with gain of 3) or should I place a buffer after the input, then feed the crossover network, then a gain stage? |
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| DC Dave |
| This pic explains my crossover integration question better. Which way should it be done, Top design or Bottom? |
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| Russ White |
| I would go with the top design. You may not need the buffer, but it is a nice touch. :) |
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