If that cap is Sufficiently Large to give "no" fall-off at the lowest audio frequency, then the voltage across it does "not" change over an audio cycle.
For this and other reasons, that cap should be *large*.
1,000uFd is 8 Ohms at 20Hz. 3 Ohms at 50Hz. Small loss, so there will be small but not real-small change of voltage on music signal.
The suggested value is 6,800uFd. A half an Ohm at 50Hz. 1/16th of the 50Hz signal voltage could appear on the cap. For 16V-24V peaks, 1.0-1.5V at most. Unless you use the MoFo for a shaker-table (or put the first minute of Hamburger Totentanz on re-peat), such a big can will not mind a bit.
Actually running 3300 uF 50w with 2.8v rms at the input of the mofo. I suppose the cap can cope with it
and I see you're using motor-run caps for signal .......
🙂
Motor run raps are gone from M2 FE 🙂
Using 10uF Simlic II and 1.25 MKC.
I'm going to listen for a good bit.
Also Paul (PSz) suggested a 20 ohm pot to replace the two 10 ohm resistors as was done in NP's Sweet Spot article. That will be next 😉
Best
Bob
you want 0mV at xformer input , other end being on GND
signal xformers doesn't like DC
Papa is cozy , taking matched JFets ....... where you can use trimpot solely to kill DC,not to fiddle with your pleasure center
signal xformers doesn't like DC
Papa is cozy , taking matched JFets ....... where you can use trimpot solely to kill DC,not to fiddle with your pleasure center
you want 0mV at xformer input , other end being on GND
signal xformers doesn't like DC
Papa is cozy , taking matched JFets ....... where you can use trimpot solely to kill DC,not to fiddle with your pleasure center
thanks ZM
Yup. I suggested twiddling the pot with the cap in place to hear the effect of THD % and character.
well , there you are in better position
I need first at least a mug of coffee in the morning , before even thinking about thinking
after that , there is only hope that my brain is willing to obey me , to stop dreaming and flip to thinking
however , more years I have , I'm caring less in which mode I am
I need first at least a mug of coffee in the morning , before even thinking about thinking
after that , there is only hope that my brain is willing to obey me , to stop dreaming and flip to thinking
however , more years I have , I'm caring less in which mode I am
Vunce, I am nearing completion on my MoFo, I really like your build photos in post 661. I purchased those same cap MX you are using, any issues with heat, they have a very small heatsink? Also, I am looking at a closed cabinet, vent holes at the top, needed or just extra. My big heatsinks are outside the enclosure.
Thanks
David
Thanks
David
Thanks David,
With the right preamp, Big MoFo is a keeper!
The Allo capMx works really well in this application and there is only about a 1.5v drop between that and the CRC. The heatsink on the mosfet gets a little warm nothing to be alarmed about.
If your going to use the barrel type input sockets on the same metal plate for both your dc power inputs, insulate them. I will eventually remove the barrel plug/socket combo and replace with the 2 conductor aviation type connectors (eBay). They secure better and are fully insulated.
This amp runs hot! Yes, the holes are needed and now I run a pair of AC Infinity 80mm fans (silent!) directly under the sinks blowing straight up them. They aren’t necessary, but I feel more comfortable with them.
Good luck with your build, looking forward to some pictures 🙂
Cheers,
Vunce
With the right preamp, Big MoFo is a keeper!
The Allo capMx works really well in this application and there is only about a 1.5v drop between that and the CRC. The heatsink on the mosfet gets a little warm nothing to be alarmed about.
If your going to use the barrel type input sockets on the same metal plate for both your dc power inputs, insulate them. I will eventually remove the barrel plug/socket combo and replace with the 2 conductor aviation type connectors (eBay). They secure better and are fully insulated.
This amp runs hot! Yes, the holes are needed and now I run a pair of AC Infinity 80mm fans (silent!) directly under the sinks blowing straight up them. They aren’t necessary, but I feel more comfortable with them.
Good luck with your build, looking forward to some pictures 🙂
Cheers,
Vunce
hello Vunce,
i am also gathering the parts and have place order for the choke.
Vunce, the All capmx is a cap multiplier ??
Any schematic ?
I am also considering one of the cap multiplier schematic from JUMA.
thank you
i am also gathering the parts and have place order for the choke.
Vunce, the All capmx is a cap multiplier ??
Any schematic ?
I am also considering one of the cap multiplier schematic from JUMA.
thank you
I am thinking of the cap multiplier schematic from the first post of this thread
25W Class A amp with Lateral MOSFETs
25W Class A amp with Lateral MOSFETs
The Allo CM board is a capMx that is commercially available. They did not release the schematic.
I’m using the Juma Easy-Peasy for my current ALPHA20 build.
Regards
Hey, I have a stupid question. Can a a SMPS be brought up with a variac?
I set the trim pot max CCW, but you never know. Want to safely bring up the MoFo.
Thanks.
I set the trim pot max CCW, but you never know. Want to safely bring up the MoFo.
Thanks.
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no stupid question
and - no
it'll idle , then squeak , then who knows ....
almost certainly nothing wrong will happen , but you'll get rail almost instantly , when you reach lowest working voltage of SMPS
and - no
it'll idle , then squeak , then who knows ....
almost certainly nothing wrong will happen , but you'll get rail almost instantly , when you reach lowest working voltage of SMPS