Hey guys and gals!
Awhile ago I got a pair of type 46 tubes which I intended to use in a headphone amp based on the Bugle. However, I realised that would've taken some time to build and I wanted a working amp in the meantime - project shelved.
Up to this point, I did not consider using the 46s for a line stage, but after seeing a Vinnie Rossi preamp and reading some stuff on Bartola Valves, I've changed my mind, so I wanna have another go with these tubes.
Current plan is like this:
- quality mains trafo (Lundahl, Sowter etc.) -> tube rectifier -> SSHV2 regulator -> B+
- "gyrator" load (Bartola design)
- Rod Coleman regulators for the filament
- maybe have the PS in a separate enclosure linked with an umbilical
- ideally it would have a motorized stepped attenuator as a volume control
Now, feel free to throw dirt at it - I'm open to people showing flaws in my plan, preferably before I spend money and time on building it wrong. I should mention I look at this as a money-no-object build.
Also, a few design questions:
- is it worth it making separate power supply rails for each channel? (ie: separate rectifiers, separate regulators)
- is a "gyrator" a better choice than a great OTP? (silver wire and such)
- could a remote affect sound in any way? (house is full of radio waves, but I'm thinking vicinity)
Awhile ago I got a pair of type 46 tubes which I intended to use in a headphone amp based on the Bugle. However, I realised that would've taken some time to build and I wanted a working amp in the meantime - project shelved.
Up to this point, I did not consider using the 46s for a line stage, but after seeing a Vinnie Rossi preamp and reading some stuff on Bartola Valves, I've changed my mind, so I wanna have another go with these tubes.
Current plan is like this:
- quality mains trafo (Lundahl, Sowter etc.) -> tube rectifier -> SSHV2 regulator -> B+
- "gyrator" load (Bartola design)
- Rod Coleman regulators for the filament
- maybe have the PS in a separate enclosure linked with an umbilical
- ideally it would have a motorized stepped attenuator as a volume control
Now, feel free to throw dirt at it - I'm open to people showing flaws in my plan, preferably before I spend money and time on building it wrong. I should mention I look at this as a money-no-object build.
Also, a few design questions:
- is it worth it making separate power supply rails for each channel? (ie: separate rectifiers, separate regulators)
- is a "gyrator" a better choice than a great OTP? (silver wire and such)
- could a remote affect sound in any way? (house is full of radio waves, but I'm thinking vicinity)
Not for me. I also find an amorphous core being more important than silver wire. Copper OCC if you can get it is best.
That's very interesting. I wasn't aware of this type of OTP, but I did some reading on Lundahl's website - seems like there's more to gain in a PP environment than SE, but it's still better. You've definitely give me something to think about.
Using a regulator for each valve to decouple them is enough. Completely seperate power supplies is overkill.
I'd build a 4P1L stage in filament bias, with Rod Coleman regs. Plenty of circuits on Bartola. Filament bias will give you a better sound than a cathode resistor and bypass cap. 46 isn't really suitable for filament bias unless you're into overkill. Ale did try it. Also have a look on Bartola for SIC diode bias. That sounds good too. The diodes he uses are expensive but good. I've used both SIC bias and filament bias. SIC is more immediate, filament bias is smoother, but not much in it. I like SIC with a 26, filament bias with a 4P1L. The 4P1L needs at least 20mA and up to 30mA is better still. Much cheaper than 46 and it's a great sound - very detailed, good treble and bass.
The SIC diodes give you roughly .85v each. So you'd need plenty for a 46. Not impossible and could sound good. Gyrator or plate choke is a personal choice. I'd give a slight preference to an amorphous core plate choke, but that's just me. Others including Ale would go for the gyrator. It's a very good circuit, and a cheaper option too. My plate chokes are from NP Acoustics in Vietnam. 180H, 40mA. Big. Love them.
The SIC diodes give you roughly .85v each. So you'd need plenty for a 46. Not impossible and could sound good. Gyrator or plate choke is a personal choice. I'd give a slight preference to an amorphous core plate choke, but that's just me. Others including Ale would go for the gyrator. It's a very good circuit, and a cheaper option too. My plate chokes are from NP Acoustics in Vietnam. 180H, 40mA. Big. Love them.
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