I've built a handful, and even in an aluminum enclosure hum wasn't an issue with Antek toroids. If you really care to, you can do the tubes and circuitry inside the case, with a separate power box connected via umbilical cable. More fussy to build, and no exposed tubes for looks, but with some adequate ventilation holes strategically placed it will last forever and be dead silent.
This MM/MC phono preamp is very quiet. AnTek toroid shielded with one of their enclosures, but upside down with an electrical box cover. . Lundahl step-ups in a steel project box. Power supply well away from signal pcb. Aluminum chassis.
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Thanks for the ideas everyone. Rather than buy new parts like the Antec transformer, I think I'll try to use stuff I already have.
I have a few pairs of 5-pin BNC-type connectors (male and female) I can use to make an umbilical. I think they're these. Male connector on the audio circuit chassis (the load), Female connector at the end of a 1m pigtail coming from the PSU box.
For the audio circuitry, I bought a Bud aluminum chassis which measures 12" L x 8" W x 3" H (305 mm L x 203 mm W x 76 mm H). It fits neatly inside a wooden box with perf board base I bought fer cheep at a local crafts store (perforated bottom will serve for ventilation once rubber feet are installed). There's more space than needed for the PCB and jacks on this Al chassis, but I suppose I can use the extra space for adding a couple of boards with LR8 regulators on them for each channel's B+.
I have a couple of Radio Shack plastic project boxes with metal plate for mounting parts. One of those should serve for housing the power transformer, rectifier (UF4007), reservoir cap and first B+ filter section.
This way I can use this power supply with different versions of 12AX7-based RIAA preamps. Perhaps I'll make a version of Eli's RIAA with grid leak bias on the 2nd stage. EQ rolling!
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I have a few pairs of 5-pin BNC-type connectors (male and female) I can use to make an umbilical. I think they're these. Male connector on the audio circuit chassis (the load), Female connector at the end of a 1m pigtail coming from the PSU box.
For the audio circuitry, I bought a Bud aluminum chassis which measures 12" L x 8" W x 3" H (305 mm L x 203 mm W x 76 mm H). It fits neatly inside a wooden box with perf board base I bought fer cheep at a local crafts store (perforated bottom will serve for ventilation once rubber feet are installed). There's more space than needed for the PCB and jacks on this Al chassis, but I suppose I can use the extra space for adding a couple of boards with LR8 regulators on them for each channel's B+.
I have a couple of Radio Shack plastic project boxes with metal plate for mounting parts. One of those should serve for housing the power transformer, rectifier (UF4007), reservoir cap and first B+ filter section.
This way I can use this power supply with different versions of 12AX7-based RIAA preamps. Perhaps I'll make a version of Eli's RIAA with grid leak bias on the 2nd stage. EQ rolling!
--
I recently built a valve headphone amp in an ali chassis. Initially I had hum problems
in spite of trying to mount the mains tx as far away from the signal circuitry as possible.
Eventually i got hum down to very low levels by minimising the power and signal lines loop area.
Because I needed to have the signal i/p on the back panel and near one of
the heater tx's I had great success with screening the i/p sockets and cables with some mu metal sheeting.
in spite of trying to mount the mains tx as far away from the signal circuitry as possible.
Eventually i got hum down to very low levels by minimising the power and signal lines loop area.
Because I needed to have the signal i/p on the back panel and near one of
the heater tx's I had great success with screening the i/p sockets and cables with some mu metal sheeting.
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