Link is dead in OP. Can you update to the new link here: Preamplifier for MM cartridge
(would be nice to have in the OP)
Are there Gerbers available for JG’s MC head amp? Perhaps PSU?
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Several years ago my pages were moved to my server, address is in my signature. You will find openamp there as well.
Pavel Macura audiopage
Pavel Macura audiopage
Agreed I used a Salas BiB shunt regulator for my Openamp-1 with no issues and no modifications of the circuit. I connected the regulator to the phono board with a short length of shielded twisted pair, about 6 inches as I recall. (and yes I mean 2 regulators, one positive one negative. The voltages were rock solid.)
I just built one of these on my own PCB. The sound is very detailed ... best bass I have heard on any phono stage to date! I would describe it as very transparent with no coloration of the sound at all. It is VERY sensitive to proximity of the power supply however. The current PCB has a 3-pin DC power jack so I can use a remote chassis which will be necessary.
Attachments
It should not be. With the original double-side PCB with top ground plane it is pretty immune to power supply proximity.
http://pmacura.cz/openamp1_M35X.GIF
I had it sitting on top of an HP dual lab supply with just a silicone pad and it hummed pretty bad! I moved the HP supply below the wooden shelf from the preamp and it got much quieter! It is not in any enclosure yet either, just a PCB with some leads hanging off of it with jumpers to the PS.
OPENAMP1 is a great design
Hello krca45,
Nice work. You made a wise choice in making this phono amp your first project. Can you describe your power supply? I am not familiar with it. I assume it is a shunt regulator.
This phono amp design, in my opinion, is outstanding. As others have stated, the low frequency “weight” is excellent and it easily powers (in my case, 32 ohm) headphones.
Hello krca45,
Nice work. You made a wise choice in making this phono amp your first project. Can you describe your power supply? I am not familiar with it. I assume it is a shunt regulator.
This phono amp design, in my opinion, is outstanding. As others have stated, the low frequency “weight” is excellent and it easily powers (in my case, 32 ohm) headphones.
Hello
Thanks
PSU is shunt regulator with mosfet IRF9510 / 510 as shunt element on the output. Uses BC546 / 556 & BD139 / 140 transistors & MMBF5486 smd jefts ( on the downside ).
Good Gemini by Zen Mod, You should be able to find him on various Pass amplifier builds.
Schematic can be found in Iron Pre preamplifier, it is a part of it, Pass section.
Regards, Krca
Thanks
PSU is shunt regulator with mosfet IRF9510 / 510 as shunt element on the output. Uses BC546 / 556 & BD139 / 140 transistors & MMBF5486 smd jefts ( on the downside ).
Good Gemini by Zen Mod, You should be able to find him on various Pass amplifier builds.
Schematic can be found in Iron Pre preamplifier, it is a part of it, Pass section.
Regards, Krca
mlloyd1,
Thanks for your feedback. While working on the complicated Non-Plus Ultra phono (by H. Polak) I began to fantasize about a more compact, simple MM phono. This and the bugle were my picks.
This may sound strange but here goes? Can the LT1010CT be replaced with a tube buffer? To get some of the "tube" sound in a phono
Thanks for your feedback. While working on the complicated Non-Plus Ultra phono (by H. Polak) I began to fantasize about a more compact, simple MM phono. This and the bugle were my picks.
This may sound strange but here goes? Can the LT1010CT be replaced with a tube buffer? To get some of the "tube" sound in a phono
you can do anything if you know what you are doing.
but first some questions:
1. do you have the expertise to make the change while maintaining the design performance?
2. what is your objective in replacing the buffer with a tube and how will you know that you have succeeded (or not)?
I'd recommend building as PMA designed first.
Get a baseline of how it sounds.
Then, make you changes and see what you think.
Just a sugggestion - you do your own thing!
but first some questions:
1. do you have the expertise to make the change while maintaining the design performance?
2. what is your objective in replacing the buffer with a tube and how will you know that you have succeeded (or not)?
I'd recommend building as PMA designed first.
Get a baseline of how it sounds.
Then, make you changes and see what you think.
Just a sugggestion - you do your own thing!
