I'm torn between "The Soundhappy" and this Hungarian amp.
He says he runs it at 40-45V and 1.2-1.5A. I've got the 2SK79s, 2SK60s and 2SJ49s sitting here...
Hello PSz. The output stage schematic for the Hungarian amp is a DEF. Its upper FET is a depletion N-channel SIT [2SK82], and its lower FET is an enhancement P-channel MOSFET [2SJ49]. The front-end N-channel depletion FET [LED in series with its source] has two jobs. Its drain current allows for biasing the DEF. It also [simultaneously] amplifies the input signal since it operates in the common source configuration. Its amplification is desired because DEF has a voltage gain of 1.
Which post# has the Soundhappy schematic? Thanks.
Hi Antoinel, yup I saw that. Thought I was missing something since the k79 is happier at higher voltages and this amp would be running it ~20V.
#75
http://blog.audiomaker.tech/pdf/soundhappy.pdf
I suspect a CCS version would lead to multiple power supplies in order to keep the K79 happy. So, let's go with the lightbulb for now.
Just guessing at ~50K-100K for the input R, 10K-20K on the Drain of the K79 and 500R-2K on the source.
Before we move on to "Soundhappy" I'll comment on the amp from Hungary. When I say the voltage is low, I'm (not intentionally) speaking shorthand. We can make the 2SK79 work adequately at lower voltage, but this being a SIT we have to be thinking about Vds and Vgs. With 22V across the part and the gate sitting at -2-3V as drawn the SIT is effectively off. At 120V B+, different story.
The information given is that we want to operate this as a power amp (not a preamp) at 45V @ 1.5A or something like that. If we replace that LED with a 100 ohm resistor or maybe a little diode like a 1N4148, now we get some current through the SIT. Give it a drain load of say 5-10k and make that pot around 50k and I think you start to have something more workable.
BTW, this is all "back of the napkin". Don't hold me to those exact values.
The information given is that we want to operate this as a power amp (not a preamp) at 45V @ 1.5A or something like that. If we replace that LED with a 100 ohm resistor or maybe a little diode like a 1N4148, now we get some current through the SIT. Give it a drain load of say 5-10k and make that pot around 50k and I think you start to have something more workable.
BTW, this is all "back of the napkin". Don't hold me to those exact values.
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Also, before we get to "Soundhappy". If you're interested in a CCS version of "Soundhappy" that's doable, but it's not a big leap from there to a 2SK79 driving a PP lateral follower, such as the ALFETs, which IMO, is a more interesting prospect than a CCS version.
The original idea (and attraction) behind "Sounhappy" was a request by it's namesake. It's a super-simple fleawatt, all Sony SIT SE amp. What could be more "Soundhappy"?
So, on we go...
The original idea (and attraction) behind "Sounhappy" was a request by it's namesake. It's a super-simple fleawatt, all Sony SIT SE amp. What could be more "Soundhappy"?
So, on we go...
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In addition to the design constraints listed above. I'm also going to constrain this to stuff that I have available in my parts stash, so I'll go take an inventory and see what I have on hand for transformers and such.
I only have a pair of 2SK79's. If I manage to blow them up, someone else will have to take over.
I only have a pair of 2SK79's. If I manage to blow them up, someone else will have to take over.
....corresponding to what I have on hand.
Funny i get the same power switch model.
Build like " tank" high quality strong electrical contact.
Start point, first components for 2SJ28 future monoblock's.
Kindest regards
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Cute !All the best amplifier designs start with the faceplate, right?
Right only if faceplate have the same speakers warnish colour haha
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Gave your comment a thumbs up which did not show.accordingly , scale print must be changed to ZEN Amount
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