pRC
New member
This phono stage is replacing an original 'beta test' Seduction from way back. The Seduction has been a mainstay in my system with only a few tweaks for 14 years (added C4S, upgraded the caps, added a shielding box over the signal area) - holy crap, that makes it the oldest survivor in the music room. But as the rest of the system evolved and everything had been replaced (sometimes by several generations), you start to get itchy. I wanted to hear what a better phono stage could do and with great experiences with Bottlehead projects and the reports online and direct from other Dixie Bottleheads the Eros was a no-brainer.
Current Vinyl Setup:
Solid cherry re-housed Lenco/Bogen TT with Schick 12-inch tonearm
Denon DL103R in aluminum body
Altec 4722 mic transformers as step-up trannies, potted in maple case inside metal jewelry box
Bottlehead Seduction phono stage
Not-so-matic 57 preamp
The system sounds pretty great but I did have some ‘site’ issues -
[list type=decimal]
[*]EM field from some high-voltage power lines next door (no house is perfect!)
[*]Ground loops to chase down (TT in on the opposite end of the room from the amp and speakers!)
[/list]
Because of the EM field in the music room and the low-voltage MC cartridge I’ve had to shield all my interconnects carefully - so this Eros would be built to fit inside a Faraday cage. And that caused a lot of cascading changes so that I could access the RCA connections and also disassemble the thing later (sure you can just solder it all up in layers as you go, but what happens if you want to go back in?)
I went with a larger chassis - using off-the-shelf 12 x 8 Hammond steel boxes. I couldn’t find a tall box for the base so I ended up stacking two 12 x 8 x 2 boxes together. These cases have an open bottom and a solid top so I cut out the top of both leaving a flange of metal in place to attach bolts. Bought a pretty handy threaded insert setter tool for an earlier machining project, so I used a lot of threaded bosses to avoid fishing out wayward nuts later…
With a bigger footprint I moved the power transformer an inch further away from the shunt reg and signal area, and mounted a Triad CX7 choke on top next door. Choke has a grounded metal cage, though I didn’t know whether it would be needed for noise.
I wanted front-mounted jacks and controls so that I wouldn’t have to fish everything through the top cage later. The jacks and switches are mounted in a machined ebony backer plate that fits through the top of the cabinet and pivots into position behind the steel front panel. Made an aluminum L bracket to attach the ebony plate so all the signal wiring could be soldered and left undisturbed during assembly/disassembly.
I’ve been using vintage microphone step-up transformers for years to mate the MC cartridges I prefer to the Seduction inputs - I’ve collected several good sets ( see: http://cognitivevent.com/av_stepup.html ). I picked one of my favorite pairs to install inside the case with the Eros, some RCA MI-12399 trannies with a weird looks-like-an-octal-but-its-really-nine-pins base. I had potted these with beeswax into a drilled block of hard maple years ago, so I cut down the block to fit the new case leaving the wiring and jacks in place, then bolted the block into one corner of the top cage.
The power input block is mounted to the back of the case, along with a chassis ground post. Again, too much behaviorally conditioning forced me to consider disassembling anything I build, so I ran a euro-strip along the side of the case for all the AC connections for the power input, power switch and neon indicator, power transformer, and chassis grounds.
I purchased the kit in 2015 and started on the project right away, but then it sat with the chassis partially completed for a long time. A really long time. Then in mid-September I kicked it back into gear.
Current Vinyl Setup:
Solid cherry re-housed Lenco/Bogen TT with Schick 12-inch tonearm
Denon DL103R in aluminum body
Altec 4722 mic transformers as step-up trannies, potted in maple case inside metal jewelry box
Bottlehead Seduction phono stage
Not-so-matic 57 preamp
The system sounds pretty great but I did have some ‘site’ issues -
[list type=decimal]
[*]EM field from some high-voltage power lines next door (no house is perfect!)
[*]Ground loops to chase down (TT in on the opposite end of the room from the amp and speakers!)
[/list]
Because of the EM field in the music room and the low-voltage MC cartridge I’ve had to shield all my interconnects carefully - so this Eros would be built to fit inside a Faraday cage. And that caused a lot of cascading changes so that I could access the RCA connections and also disassemble the thing later (sure you can just solder it all up in layers as you go, but what happens if you want to go back in?)
I went with a larger chassis - using off-the-shelf 12 x 8 Hammond steel boxes. I couldn’t find a tall box for the base so I ended up stacking two 12 x 8 x 2 boxes together. These cases have an open bottom and a solid top so I cut out the top of both leaving a flange of metal in place to attach bolts. Bought a pretty handy threaded insert setter tool for an earlier machining project, so I used a lot of threaded bosses to avoid fishing out wayward nuts later…
With a bigger footprint I moved the power transformer an inch further away from the shunt reg and signal area, and mounted a Triad CX7 choke on top next door. Choke has a grounded metal cage, though I didn’t know whether it would be needed for noise.
I wanted front-mounted jacks and controls so that I wouldn’t have to fish everything through the top cage later. The jacks and switches are mounted in a machined ebony backer plate that fits through the top of the cabinet and pivots into position behind the steel front panel. Made an aluminum L bracket to attach the ebony plate so all the signal wiring could be soldered and left undisturbed during assembly/disassembly.
I’ve been using vintage microphone step-up transformers for years to mate the MC cartridges I prefer to the Seduction inputs - I’ve collected several good sets ( see: http://cognitivevent.com/av_stepup.html ). I picked one of my favorite pairs to install inside the case with the Eros, some RCA MI-12399 trannies with a weird looks-like-an-octal-but-its-really-nine-pins base. I had potted these with beeswax into a drilled block of hard maple years ago, so I cut down the block to fit the new case leaving the wiring and jacks in place, then bolted the block into one corner of the top cage.
The power input block is mounted to the back of the case, along with a chassis ground post. Again, too much behaviorally conditioning forced me to consider disassembling anything I build, so I ran a euro-strip along the side of the case for all the AC connections for the power input, power switch and neon indicator, power transformer, and chassis grounds.
I purchased the kit in 2015 and started on the project right away, but then it sat with the chassis partially completed for a long time. A really long time. Then in mid-September I kicked it back into gear.
