And there's a 300k fixed resistor in the photo, so I'm not sure I follow this little thought experiment.
Haha! Oh well, that thing was OT anyhow. No 2SJ28s anywhere in sight.
Ok, back to R values for "The Soundhappy". Where should I start?
Ok, back to R values for "The Soundhappy". Where should I start?
I think the 300k resistor is from output to ground, so this is probably the preamp, which works on 120V, which makes a lot more sense.
As for "Soundhappy", shall we start with CCS or lightbulb?
🙂
As for "Soundhappy", shall we start with CCS or lightbulb?
🙂
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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Perhaps the Hungarian amp would work at 40-45V and 1.2-1.5 amps using a 2SK170 up front.
Or to stay on topic flip the PSU and use 2SK134 (or similar) and an orphan p channel SIT to form a DEF amp.
Or to stay on topic flip the PSU and use 2SK134 (or similar) and an orphan p channel SIT to form a DEF amp.
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. 🙂
That sounds cool too. But if we're gonna go there then why not go fully exotic and drive a DEF with the 2SK79 SRPP preamp from Japan.
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 !
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
DIY version of Imperial. 😀
PAPA and King Tubby installed Tannoy to variations of Imperial, so it must be an excellent BLH enclosure.
