L'Amp: A simple SIT Amp

Jump to Latest
cwtim01

cwtim01

Member
Joined 2012
jama said:
This pcb is Soekris dac, and Mr. Pass buffer with 2sk170 and 2sj74 matched. The final idea is digital input and output to speakers.
Click to expand...

Wow, a fully integrated L'Amp :up:

Albert's pair of 2SK180 is a matched pair I received from generg before, and I passed them onto him. He asked me the difference between the various versions (bulb, resistor, 193V, ccs) and I couldn't answer, but now he has all the info :)
 
Soundhappy

Soundhappy

Member
Joined 2012
jama said:
Hello albertli. Your idea of making lamp with 2sk180 is very good. I have done some versions. The first was with thf51 and 65Vdc 4A of quiescent current. The second one with 2sk180D and 84Vdc 2A; next one with thf51 and the same that second one. And the last with 193V and thf51.
All except the last one were done with resistor (10 ohm 600W and 22 ohm 300W) as drain load.
For me, the first is the better, but heat dissipation was enormous (240W) and the gigant heatsink (50cm x 30 cm and 8 cm) impossible of touch. I got almost 18W rms. Sound, for me very very good. The second better (actual amp) is thf51 with 84Vdc and 2A. With this I get 8Wrms. Enough for me (I am using 100db speakers in open baffle).
The third version, with 2sk180D selected, had worse highs than thf51. Sorry, this was my impression. When I used a scope, I saw that all measurements all worse than thf51, square wave, frequency response and output impedance (more o less 4 ohm). I do not know why nobody want to try this wonderful vfet. I am using low output impedance pre and highs are wonderful.
The last one, 193V version will be a gift for a friend, and sound, for me, is a little dark compare with resistor version. The advantage is heat dissipation a lot lower.
One thing more. For getting channels sound equal,you need select very well vfets. If you can, try use a economic curve tracer, as there is in ebay, because variability is a lot bigger than 2sk82.
If you can get 2sk180, try get D version. They are very very similar each other (at least I own).

Well, good luck in your project.
Click to expand...
Very nice to get DAC inside Tokin L'Amp :)
Congratulations for all interesting work Jama.
Why not thf ?
Well biger capacitance and not doubt because Mr Pass say next after 2SK77B are article with 2SK180 on First Watt fabulous.
Big :cheers: amigos Jama , Dady, Cwtim01 and WalterW
Happy New Years 2016 for All Diyers Vfet, Sits aficionados :happy1:
 
albertli

albertli

Member
Joined 2004
cwtim01 said:
Wow, a fully integrated L'Amp :up:

Albert's pair of 2SK180 is a matched pair I received from generg before, and I passed them onto him. He asked me the difference between the various versions (bulb, resistor, 193V, ccs) and I couldn't answer, but now he has all the info :)
Click to expand...

Tim, Thanks
I thought I'd go for the 193v to save some energy.
What I have on hand, 400VA 30V tranny. I have around 42v after rectified. I don't have big caps, they're all 10,000uf. I'd try CRCRC, with C=20,000uf and R=0.5-1 ohm. Still waiting for the 180 to arrive. Let you know.
Thanks again
Albert
 
albertli

albertli

Member
Joined 2004
jama said:
This pcb is Soekris dac, and Mr. Pass buffer with 2sk170 and 2sj74 matched. The final idea is digital input and output to speakers.
Click to expand...

Jama,
Thanks for all the infos.
I'd build the buffer like you. Please take a look and see if it's the buffer you put on yours. Eh....what cap you use on output ?
Albert
 

Attachments

  • buffer.PNG
    buffer.PNG
    10 KB · Views: 805
J

jama

Member
Joined 2004
Hi, Albert. Yes, this is the buffer I use. With 193V you do not need a lot of caps in PS. Mine (193V version) have two 22k 0.1ohm 22k, and it is absolutely silent. No hum, nothing. But resistor version, have a little hum (CLCLC in PS, with C 22k 100V and L 2.2mH). I use 10k parallel with 2uf at output. And for input position, 2.2uF.
 
J

jama

Member
Joined 2004
I do not hear CCS version yet. Two months ago I tried baf version but it not works for me. I broke the mosfet (gate and its resistor burned with nice smoke....) and, oh my god, the vfet too (gate). But I never surrender.... I will try again soon.
 

Attachments

  • 20160111_064753_resized.jpg
    20160111_064753_resized.jpg
    350.6 KB · Views: 797
  • 20160111_064822_resized.jpg
    20160111_064822_resized.jpg
    329.1 KB · Views: 779
  • 20160111_075948_resized.jpg
    20160111_075948_resized.jpg
    322.7 KB · Views: 778
albertli

albertli

Member
Joined 2004
jama said:
Hi, Albert. Yes, this is the buffer I use. With 193V you do not need a lot of caps in PS. Mine (193V version) have two 22k 0.1ohm 22k, and it is absolutely silent. No hum, nothing. But resistor version, have a little hum (CLCLC in PS, with C 22k 100V and L 2.2mH). I use 10k parallel with 2uf at output. And for input position, 2.2uF.
Click to expand...

Jama,
Thanks for your reply.
Is 2.2uf at input good for 20-20,000. I can use whatever number in between then. I don't have to buy the 10uf, great.
 
albertli

albertli

Member
Joined 2004
Got a pair of 180 today from Tim today . They're way bigger than what I thought. All mica insulator I have is not big enough for the job. I have to source the right one now. Any ideas? Or point me to anywhere I could find them.
Thanks
Albert
 

Attachments

  • IMG_20160114_201909.jpg
    IMG_20160114_201909.jpg
    287.7 KB · Views: 618
wrenchone

wrenchone

Member
Joined 2004
albertli said:
Hi guys,
I start to collecting parts for making this amp with 180.
I have some inductors on my stock with 14awg wire. They measured at 0.2 mH, 0.1 ohm with a magnet in the middle.
Are they good for the power supply filter?
Thanks
Albert
Click to expand...

Zen is wrong for once. It's not a magnet in the middle, it's a ferrite rod. If it were a toroidal ferrite inductor with no gap, it would saturate quickly with application of current, as pretty much all respectable ferrites are gone and saturated at 2 oe and no gap.
However, since it is just a ferrite rod, the effective air gap is huge, and the inductor will support a fairly large current before the core saturates (even then, the inductance won't entirely go away). Consult the spec for the inductor regarding recommended DC current.
If you want more surety, wind up an inductor using a powdered iron or sendust material. These have a distributed gap due to the material characteristics, and only saturate gradually with application of DC current.
 
Soundhappy

Soundhappy

Member
Joined 2012
albertli said:
Got a pair of 180 today from Tim today . They're way bigger than what I thought.
All mica insulator I have is not big enough for the job. I have to source the right one now.
Any ideas? Or point me to anywhere I could find them.
Thanks
Albert
Click to expand...

Response on that question are in Uncle video Lab Hangout 2.1
it start at 27'min about 2SK180/ 182 thermal pads solutions.

https://www.youtube.com/watch?v=fbezSiQzkm4

Greetings :happy1:
 
You must log in or register to reply here.
Top Bottom