The requirement for the JFET is that it will conduct 5mA with a gate-source voltage in the -1V to -4V range. If Q4 is not in that range, you will not be able to set the output voltage with P1.
Be sure to verify the pin-out of any substitute part. The 2SK170 has the gate on the middle pin. Many 2N or MPF parts have the gate on the pin that would be the collector of a 2N3904, the leads will have to be twisted to connect to the PCB layout. Generally JFETs like these will work just fine with the Source and Drain interchanged.
Be sure to verify the pin-out of any substitute part. The 2SK170 has the gate on the middle pin. Many 2N or MPF parts have the gate on the pin that would be the collector of a 2N3904, the leads will have to be twisted to connect to the PCB layout. Generally JFETs like these will work just fine with the Source and Drain interchanged.
Built my first p2p. THANKS PAPA!
Nelson Pass Amp Camp | retrofit into a Orion 1200d (600@1 class d)
First, is my temperature ok?
Averaging 48c after 8 hours/ all day of use.
It gets hot. I can hold my hand on it. I would like it to run cooler.
~ 25c ambient +25c dissipation = <50c so I am ok?
15vac100va dual secondary antek transformer
33,000uf 50v nippon chem
18vdc full load PS
10.1vdc Q1
dead silent, no hum
current setup with amp:
Tang bang 926s 1 cuft @ 80 hz @ 4 ohms
audio gd nfb 12 dac via toslink
Sound blaster Recon 3d Pro
Foobar wasapi 16bit 44.1khz
made with many left overs. upgrades to come.
Tang Band W3-926SD 3" Poly Cone Neodymium Full Range Driver 264-815
33000uf/50V-Repeat Of A Sell Out
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Nelson Pass Amp Camp | retrofit into a Orion 1200d (600@1 class d)
First, is my temperature ok?
Averaging 48c after 8 hours/ all day of use.
It gets hot. I can hold my hand on it. I would like it to run cooler.
~ 25c ambient +25c dissipation = <50c so I am ok?
15vac100va dual secondary antek transformer
33,000uf 50v nippon chem
18vdc full load PS
10.1vdc Q1
dead silent, no hum
current setup with amp:
Tang bang 926s 1 cuft @ 80 hz @ 4 ohms
audio gd nfb 12 dac via toslink
Sound blaster Recon 3d Pro
Foobar wasapi 16bit 44.1khz
made with many left overs. upgrades to come.
Tang Band W3-926SD 3" Poly Cone Neodymium Full Range Driver 264-815
33000uf/50V-Repeat Of A Sell Out
An externally hosted image should be here but it was not working when we last tested it.
An externally hosted image should be here but it was not working when we last tested it.
Uploaded with ImageShack.us
Uploaded with ImageShack.us
Way, way back - 6L6 suggested a Peter Daniels Universal PS board as a match for the ACA. I finally go them stuffed and working yesterday. The sound quality is great and I perceive more and cleaner bass as well as improved dynamics.
Kudos Mr. Pass
The only glitch is a very warm transformer at max volume, which I haven't experienced over in the chip amp world. My first guess is the toroid isn't big enough but I'll take the advice of the experts.
Antek AN-0215 25VA 0.8Amp
ApexJr 18,000 uF 50V Caps
Arcol 5W 0.47 ohm resistors
Kudos Mr. Pass
The only glitch is a very warm transformer at max volume, which I haven't experienced over in the chip amp world. My first guess is the toroid isn't big enough but I'll take the advice of the experts.
Antek AN-0215 25VA 0.8Amp
ApexJr 18,000 uF 50V Caps
Arcol 5W 0.47 ohm resistors
Attachments
The only glitch is a very warm transformer at max volume, which I haven't experienced over in the chip amp world. My first guess is the toroid isn't big enough but I'll take the advice of the experts.
Antek AN-0215 25VA 0.8Amp
ApexJr 18,000 uF 50V Caps
Arcol 5W 0.47 ohm resistors
iirc, the psu should provide 2.2A per channel when running at 19 volts.
I see yours isn't quite 19v but it still seems undersized.
best,
N-Brock
25VA ???????? I'm surprised it hasn't melted the tape off it yet!!! That's seriously undersized, you need something closer to 150-200VA.
The laptop PSU used are probably 60-90W output, each. You will need 1 transformer that can supply both channels, so 150-200VA (VA are basically equal to W)
That aside, your build looks really nice, I wish I could come over and hear it!
I'm surprised it hasn't melted the tape off it yet!!! That's seriously undersized, you need something closer to 150-200VA. The laptop PSU used are probably 60-90W output, each. You will need 1 transformer that can supply both channels, so 150-200VA (VA are basically equal to W)
That aside, your build looks really nice, I wish I could come over and hear it!
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"Papa" Pass says :"There are literally tons of surplus supplies available for this purpose, providing regulated 19 volts DC at more than 2 amps or so....."
The most recent ones we supplied in the store are rated 4.7A at 19v. so in theory one could handle 2 ch. which would be cheaper, but we DIYers like to be sure! And having 2 PSU's adds features envisioned by Nelson: Monoblocks with individual and remote power supplies!
So from the article 100VA should work for the 2 ch. but I'd go 150 for a shared power supply..
The most recent ones we supplied in the store are rated 4.7A at 19v. so in theory one could handle 2 ch. which would be cheaper, but we DIYers like to be sure! And having 2 PSU's adds features envisioned by Nelson: Monoblocks with individual and remote power supplies!
So from the article 100VA should work for the 2 ch. but I'd go 150 for a shared power supply..
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Hey Variac,
I have two 18.5V PC portable power supplies that have been used with the ACAs. The PD boards were as much a learning tool as an end in themselves. Lots of new adventures as I dip my toe into the world of discrete amps. Like so many things, this and another PS project from another thread have cleared away a lot of the fog that accumulates by just reading posts - "Oh, thats what they were talking about"
Looking forward to more Pass fun and sophistication
I have two 18.5V PC portable power supplies that have been used with the ACAs. The PD boards were as much a learning tool as an end in themselves. Lots of new adventures as I dip my toe into the world of discrete amps. Like so many things, this and another PS project from another thread have cleared away a lot of the fog that accumulates by just reading posts - "Oh, thats what they were talking about"
Looking forward to more Pass fun and sophistication
