Aha!
(So how did I get it...?) I'm a dog, not a 13-yr old Swedish folktale supergirl...
😀 😀 😀
LMAO!
Was special ZM edition.
nope
ZM's having some other special editions , but not that one
even we , Supergirls , are not having absolute precognition
Attachments
collected/prepared most of the parts
now just to collect some brain and time
in fact , ignore that brain part ..... just time
... in case that I didn't sped up things with Iron Pre (ask 6L6 why) , I would be writing hilarious Cook Book right now ......
now just to collect some brain and time
in fact , ignore that brain part ..... just time

... in case that I didn't sped up things with Iron Pre (ask 6L6 why) , I would be writing hilarious Cook Book right now ......
Build guide
Jim
I'm guessing a lot of people will be using the universal PSU. Will your build guide incorporate recommendations for optimal implementation of it for the VFET amp?
Jim
I'm guessing a lot of people will be using the universal PSU. Will your build guide incorporate recommendations for optimal implementation of it for the VFET amp?
Studley - Of course.
But honestly, the normal FirstWatt recipe will work just fine here, (8x 15,000uF caps, 8 0.47ohm 3W resistors, etc...) Remember to use 35v caps. The 4U 300mm chassis gets pretty tight with the T-brackets, and there's not really room for the discrete diode bridges. I just use bridge blocks. (Which I prefer anyway...)
But honestly, the normal FirstWatt recipe will work just fine here, (8x 15,000uF caps, 8 0.47ohm 3W resistors, etc...) Remember to use 35v caps. The 4U 300mm chassis gets pretty tight with the T-brackets, and there's not really room for the discrete diode bridges. I just use bridge blocks. (Which I prefer anyway...)
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Studley - Of course.
But honestly, the normal FirstWatt recipe will work just fine here, (8x 15,000uF caps, 8 0.47ohm 3W resistors, etc...) Remember to use 35v caps. The 4U 300mm chassis gets pretty tight with the T-brackets, and there's not really room for the discrete diode bridges. I just use bridge blocks. (Which I prefer anyway...)
That's great. I'm on a steep learning curve and really appreciate the leg up that generous people like you provide here on DIYA.
Studley - Of course.
But honestly, the normal FirstWatt recipe will work just fine here, (8x 15,000uF caps, 8 0.47ohm 3W resistors, etc...) Remember to use 35v caps. The 4U 300mm chassis gets pretty tight with the T-brackets, and there's not really room for the discrete diode bridges. I just use bridge blocks. (Which I prefer anyway...)
Here is a 35mm 105º 33000uf capacitor.
http://pt.mouser.com/ProductDetail/...=sGAEpiMZZMtZ1n0r9vR22Yj4l4UaFwO0QRc9ayIn3uw=
You can have quite a large capacitance using the universal psu board.
There should be threaded holes on the inside of the front panel, where you can mount the diodes or bridge blocks. The panel is 10mm thick so a very nice heatsink..
Bridged power output
If I'm lucky enough to get a second kit then I'd like to bridge the amps. I want to work out how many wpc a bridged amp would deliver into a 20 ohm load. The stereo amp does 20wpc into 4ohms, so using the doubling rule a bridged amp could potentially do 40wpc into 8ohms. By my calculations that equates to about 18v (V sqd = P x R). Using P = Vsqd / R I get P = 324/20 = 16
So that's 16wpc into 20 ohms.
Is that correct or have I (very likely) overlooked something?
If I'm lucky enough to get a second kit then I'd like to bridge the amps. I want to work out how many wpc a bridged amp would deliver into a 20 ohm load. The stereo amp does 20wpc into 4ohms, so using the doubling rule a bridged amp could potentially do 40wpc into 8ohms. By my calculations that equates to about 18v (V sqd = P x R). Using P = Vsqd / R I get P = 324/20 = 16
So that's 16wpc into 20 ohms.
Is that correct or have I (very likely) overlooked something?
You have a 20 ohm speaker load?
Yup. It's a compression driver in an active set up.
I think I see where 6L6 is going with this.
Studley, for my just completed F4, I have enough volume with 0.9v max from my DAC. In an active setup. With a Radian compression driver.
It seems like one VFET should be plenty, unless I'm missing something...
Studley, for my just completed F4, I have enough volume with 0.9v max from my DAC. In an active setup. With a Radian compression driver.
It seems like one VFET should be plenty, unless I'm missing something...
Ah. Makes sense. Compression drivers are really efficient...
The standard amp's 8 watts can't make it play at ear-damaging levels? (36v pk-pk = 12.72vrms^2 = 161.8/20ohm = 8.09w)
The standard amp's 8 watts can't make it play at ear-damaging levels? (36v pk-pk = 12.72vrms^2 = 161.8/20ohm = 8.09w)
The output devices have approx. 18V rails. That's 36V pk-pk.
Bridging doubles your output voltage, to 72V pk-pk
Power is Vrms^2/load=watts
72v pk-pk *.3535=25.45vrms
25.45v^2 = 647.8
647.8/20 = 32w
Bridging doubles your output voltage, to 72V pk-pk
Power is Vrms^2/load=watts
72v pk-pk *.3535=25.45vrms
25.45v^2 = 647.8
647.8/20 = 32w
The stereo amp does 20wpc into 4ohms, so using the doubling rule a bridged amp could potentially do 40wpc into 8ohms. By my calculations that equates to about 18v (V sqd = P x R). Using P = Vsqd / R I get P = 324/20 = 16
So that's 16wpc into 20 ohms.
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I think I see where 6L6 is going with this.
Studley, for my just completed F4, I have enough volume with 0.9v max from my DAC. In an active setup. With a Radian compression driver.
It seems like one VFET should be plenty, unless I'm missing something...
There's a pad in front of the CD that eats a load of power, so a stereo amp won't be enough.
No can do.I'm guessing you can't put the pad at line level before the VFET amp for various reasons?
The output devices have approx. 18V rails. That's 36V pk-pk.
Bridging doubles your output voltage, to 72V pk-pk
Power is Vrms^2/load=watts
72v pk-pk *.3535=25.45vrms
25.45v^2 = 647.8
647.8/20 = 32w
Thanks Jim. I can see that I didn't do the right thing to calculate the Vrms of the bridged amp.
The pad will effectively reduce that 32wpc to about 3w, but the CD has a sensitivity of >100dB, so that's enough 😀
Thanks
I have a large 18-18VAC 600VA transformer - it is used for my L'amp project but is "outboard" from that cabinet - can I also use it for this project? (or do I need to use a 22-22VAC transformer as I have read here?).
What kind of power output are we talking from these modules into a an 8 ohm load? (specifically, Fostex Fe206en?)
thanks!
What kind of power output are we talking from these modules into a an 8 ohm load? (specifically, Fostex Fe206en?)
thanks!
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