sorry to Ask , but i already have an amp with a 600Va 2x25V power transformer so i will probably get a + - 30V on each rail . do i need to change something on the schematic ( source resistor ?) or just lower the bias ?
🙂
🙂
and last 😀 if i use a 300B amplifier with its 16 ohm output tap do i need to add a 16R resistor in parrallele with the 47K ?
🙂
🙂
if you're going to use it exclusively that way, your toob amp is better buffer than eeenyweeny Toshibas
so, no need for buffer, use Crippled F4
so, no need for buffer, use Crippled F4
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Okay,
Just fired up my F4, no smoke, but I need to decrease R9, only getting some 90mAh across the source. I only have 1.5k in my parts. How low can I go with R9??
Cheers,
Greg
Just fired up my F4, no smoke, but I need to decrease R9, only getting some 90mAh across the source. I only have 1.5k in my parts. How low can I go with R9??
Cheers,
Greg
if you had properly biased amp before, there must be a reason for change
so, few details more, pretty please
one channel, both channels ? (even if in case of "both channels" better to ask some Voodoo specialist)
🙂
so, few details more, pretty please
one channel, both channels ? (even if in case of "both channels" better to ask some Voodoo specialist)
🙂
ok, now I realized that you're talking about new, just assembled one
you can put 3pcs of 1K5 in series , to get some 4K5 in place of R9
you can put 3pcs of 1K5 in series , to get some 4K5 in place of R9
Choky,
Found some 10ks last night. Biased up this morning. Driving it with cathode follower at only 3.5v, straight out of my dac. Surprisingly loud enough, but, I’ll need a proper linestage.
It definitely is one of the coolest things I’ve ever built. I’m basically listening to my dac through the loudspeaker. There is a fraction of SS to the sound. But, I definitely see what brilliance this thing is: It really sounds as it’s supposed to sound: like the source.
TDA1541->Class A I/V->5687 follower->F4>Montis
Cheers,
GG
Unbalanced
89db (Martin Logan lists it at 91db, but I don't believe that number. The salient point is that it has a powered woofer, which is obviously makes a huge difference. I run this loudspeaker with SET amps at 2-3 watts. People have tried to school me on the forums that this isn't possible, but they aren't considering the impedance load presented by this design. I do have a HE loudspeaker of my design that is in the 96db range that I need to try with the F4.)
Some of the higher gain tracks I listened to this morning were high enough that I had to turn the volume down (digital volume). OTOH, I still need a proper tube linestage. I've got a gaggle of SS linestages that are wonderful, but these days tube stuff is really where it's at for me). Last year I built a 300b linestage but I sold it to fund another project. DOH!
With just 3.5v, I don't see this as a solution for everyone, but in my case it actually works because of the loudspeaker. So, if you've got a true HE loudspeaker you could drive the F4 with very low voltage and get away with it.
The very simple signal chain that I have is pretty remarkable. After about an hour of warm-up I thought that the F4 did indeed sound like the simple cathode follower driving it: smooth, great separation and scale.
I'm planning two linestages, both single tube.
Cheers,
Greg
Balanced input from a Buffalo DAC, digital volume control. Low sensitivity bookshelf speakers in a small bedroom. I run the volume around 60% at my normal listening levels. There will certainly be situations where it wouldn't be a good fit if you require plenty of drive. I also use an autoformer for another 6db of gain. Sounds really nice though.