Q: I really like my buffered volume control (BVC) and it sounds great to me and the kind of music I enjoy listening to. So why am I planning to rebuild it?
A: Because it's there!
Not having any mountains to climb, at least for the present, I always wanted to say that. Now, to the specifics: My present set-up, which I use to listen to CD's and my FM tuner, consists of a dual 50K Alps pot driving one AD845 op amp per channel connected in non-inverting voltage follower mode. Very simple and basic but it seems to work very well.
First, I plan to replace the Alps pot with a 50K stepped attenuator. Probably 24-position unless a 47-position would be more useful?
Second and last, I want to build a remote power supply mounting the transformer and the rectifiers in a separate enclosure connected to the BVC enclosure with an umbilical cord thus removing all AC from the signal-carrying section. The separate power supply will house a 3-conductor line cord (grounded to the PS chassis), a SPST on-off switch, a fuse holder, an Avel-Lindberg 100VA, 18V transformer, 2 bridge rectifiers (one for each of the A-L two secondary circuits, with the diodes bridged by .01uF metallized polypropylene caps) and two 1000uF, 35V electrolytic caps at the output. The 1000uF caps will add to the 4700uF caps already in place on the PS board mounted next to the signal-carrying board in the BVC enclosure. The bridge rectifiers and bypass caps will be removed from the PS board as they will no longer be needed.
BTW, the PS board was designed by Grayson King and I populated it with all the components that he recommended so I'm sure it's of the highest quality. I obtained it from the days of Audio Amateur magazine when they use to sell a great variety of materials for the DIYer. I also have his board for the preamp he designed but have not used it because I only wanted a simple buffer whereas the King board provides gain. How I loved that magazine!
A couple of questions I can think of off the bat: I'm using a star ground system in my BVC enclosure where the power supply board is also grounded. Should I also ground the PS to the remote PS enclosure where the line cord is grounded or avoid that connection?
Finally, would it be worthwhile to employ a SS relay for turn-on or would it be unnecessary or overkill? I was thinking of the Crydom A1210 for example which turns on at zero crossing. Whether or not I use it will also determine the dimensions of the separate PS enclosure I will need and as I'm in the process of gathering the parts I need construction will take a little time.
Thanks to all who read this as while I enjoy building relatively simple audio projects admittedly I am a rank amateur in the field of audio. I would certainly appreciate any suggestions one might have.
A: Because it's there!
Not having any mountains to climb, at least for the present, I always wanted to say that. Now, to the specifics: My present set-up, which I use to listen to CD's and my FM tuner, consists of a dual 50K Alps pot driving one AD845 op amp per channel connected in non-inverting voltage follower mode. Very simple and basic but it seems to work very well.
First, I plan to replace the Alps pot with a 50K stepped attenuator. Probably 24-position unless a 47-position would be more useful?
Second and last, I want to build a remote power supply mounting the transformer and the rectifiers in a separate enclosure connected to the BVC enclosure with an umbilical cord thus removing all AC from the signal-carrying section. The separate power supply will house a 3-conductor line cord (grounded to the PS chassis), a SPST on-off switch, a fuse holder, an Avel-Lindberg 100VA, 18V transformer, 2 bridge rectifiers (one for each of the A-L two secondary circuits, with the diodes bridged by .01uF metallized polypropylene caps) and two 1000uF, 35V electrolytic caps at the output. The 1000uF caps will add to the 4700uF caps already in place on the PS board mounted next to the signal-carrying board in the BVC enclosure. The bridge rectifiers and bypass caps will be removed from the PS board as they will no longer be needed.
BTW, the PS board was designed by Grayson King and I populated it with all the components that he recommended so I'm sure it's of the highest quality. I obtained it from the days of Audio Amateur magazine when they use to sell a great variety of materials for the DIYer. I also have his board for the preamp he designed but have not used it because I only wanted a simple buffer whereas the King board provides gain. How I loved that magazine!
A couple of questions I can think of off the bat: I'm using a star ground system in my BVC enclosure where the power supply board is also grounded. Should I also ground the PS to the remote PS enclosure where the line cord is grounded or avoid that connection?
Finally, would it be worthwhile to employ a SS relay for turn-on or would it be unnecessary or overkill? I was thinking of the Crydom A1210 for example which turns on at zero crossing. Whether or not I use it will also determine the dimensions of the separate PS enclosure I will need and as I'm in the process of gathering the parts I need construction will take a little time.
Thanks to all who read this as while I enjoy building relatively simple audio projects admittedly I am a rank amateur in the field of audio. I would certainly appreciate any suggestions one might have.
I guess I found the answer to my second question about using a SSR with zero crossing function to turn on a transformer. It's not a good idea according to the following reference:
https://www.te.com/commerce/Documen...v&DocNm=13C3206_AppNote&DocType=CS&DocLang=EN
In Grayson King's original power supply circuit, which I am utilizing, he saw no need to provide transformer surge limiting so I feel safe in following suit.
https://www.te.com/commerce/Documen...v&DocNm=13C3206_AppNote&DocType=CS&DocLang=EN
In Grayson King's original power supply circuit, which I am utilizing, he saw no need to provide transformer surge limiting so I feel safe in following suit.
Unless you listen at low volumes a lot, you'll only use a fraction of the range of the control.
That area could have smaller steps (1dB or 2dB), with the rest of the steps larger at lower settings.
That area could have smaller steps (1dB or 2dB), with the rest of the steps larger at lower settings.
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rayma, thank you for your reply. I don't tend to listen to music at low volume levels most of the time but rather closer to what one might hear in the concert hall. I assume then that you are advising I stick to the 24-position stepped attenuator?