Mine is still suffering hum issues, I'm convinced I need to regulate my voltage. Pelayostyle, I'm wondering how you're going to configure the boards. What filtering are you gonna do before the millett regulators? What transformer taps are you using?
Hi Adam,
I'll be using this Filament Regulator which is basically the same circuit as Pete Millet's but this one uses a low dropout regulator in order to get regulated 6.3V DC from 6.3V AC. Just one board for both tubes in parallel.
I'm also using the Edcor XPWR123 which is essentially a clone of the Allied 6K3VG.
Tube Phono preamp.
Works with Audio-Technica AT-95E cartridge
EF86 - STR85/10 - 6P14P(EL84)trio - ECC82 (optional)
Two outputs by chioce depending on length of a cable.
Works with Audio-Technica AT-95E cartridge
EF86 - STR85/10 - 6P14P(EL84)trio - ECC82 (optional)
Two outputs by chioce depending on length of a cable.
Attachments
I use one of these in one of my phono amps... Works like a charm!
DC-DC 8-32V to 45-390V Step Up Power Supply Module High Voltage ZVS Boost Module | eBay
DC-DC 8-32V to 45-390V Step Up Power Supply Module High Voltage ZVS Boost Module | eBay
Maybe Hi_Q has 12V mains?I'm pretty sure he has a power transformer, and has just not shown it in this schematic.
I use transformer with 230v and 12v secondairies.Death circuit No mains isolation
Just bought the filament regulator, hopefully that clears up hum, and otherwise I'm going to completely re-do my grounding. It's been a long journey, but I still have hope that it's all going to pay off in the end. Also, I'm designing a pair of baby hueys, and have access to a CNC machine and tons of HDPE, but no tooling for aluminum. Will HDPE work for the plates while I save up for tooling?
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A lot of MM carts spec 150pF+ of capacitance loading. That just so happens to be about the Miller Cap of a grounded cathode 12AX7 with a resistor load:
150k load, 66k Rp, Mu 100
100 * 150k / (150k + 66k) = 70x gain
71 gain * 1.7pF Cga + 1.6pF Cgk = 120pF+
OTOH MC carts don't like that large of a capacitive load and so a grounded cathode 12AX7 is not as good of a match. I'm not sure if high output MC carts tend towards MM type loading or MC loading (or if there is any general trend that could be identified).
Cascode input type preamps might be a better match for a MC cart as they sidestep the Miller cap issue.
150k load, 66k Rp, Mu 100
100 * 150k / (150k + 66k) = 70x gain
71 gain * 1.7pF Cga + 1.6pF Cgk = 120pF+
OTOH MC carts don't like that large of a capacitive load and so a grounded cathode 12AX7 is not as good of a match. I'm not sure if high output MC carts tend towards MM type loading or MC loading (or if there is any general trend that could be identified).
Cascode input type preamps might be a better match for a MC cart as they sidestep the Miller cap issue.
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