James Evans
Bedroom Bodger
Right then, acquired my obelisk 3 with no phono card in it, so thought I'd build one. Found the below schematic for a single supply opamp based mm stage:
MM Stage
The original power supply lines provided +30v so I've got a vbe dropping that to +20v and then lt1086 dropping it to +10v (thought I might try the AD8620 at some point which has max input of +13v)
Input and output caps, and small decoupling caps, are polypropylene, 10uf and 22uf caps are polyester, only lytic is the 100uf.
After a few startup niggles the damn thing works, huzzah, but, there's no bass, at all...
It's being used as a plugin card with this pre:
obelisk 3 pre
the only mods done to that pre are the input coupling caps have been swapped for 3.3uf polypropylene.
Gain on the MM card sounds about right - at 10 o'clock the bass-light signal is a nice listening level.
don't have a great deal of time to dedicate to swapping stuff around, so, any pointers as to where to start looking?
I'm thinking maybe the input and output caps should be larger than 3.3uf?
should the 22uf decoupling cap be bigger?
cheers in advance for any pointers
James
MM Stage
The original power supply lines provided +30v so I've got a vbe dropping that to +20v and then lt1086 dropping it to +10v (thought I might try the AD8620 at some point which has max input of +13v)
Input and output caps, and small decoupling caps, are polypropylene, 10uf and 22uf caps are polyester, only lytic is the 100uf.
After a few startup niggles the damn thing works, huzzah, but, there's no bass, at all...
It's being used as a plugin card with this pre:
obelisk 3 pre
the only mods done to that pre are the input coupling caps have been swapped for 3.3uf polypropylene.
Gain on the MM card sounds about right - at 10 o'clock the bass-light signal is a nice listening level.
don't have a great deal of time to dedicate to swapping stuff around, so, any pointers as to where to start looking?
I'm thinking maybe the input and output caps should be larger than 3.3uf?
should the 22uf decoupling cap be bigger?
cheers in advance for any pointers
James