I bought two 2SK180Ds yesterday from an ebay merchant, and I was actually thinking about using them single ended with choke loading. I just can't stop.
I have a Hammond 193V loaded 2SJ28 L'Amp that I am thinking of repurposing for the 2SK180Ds. I will need a new power transformer and more heatsinking but I will be able to use the rest of the parts.
I did some LTSpice simulations, trying MR's operating point from his light bulb L'Amp (Vds 36V Iq 2.1A), and also after some playing around, Vds 29V and Iq 3.0A.
When I get my 2SK280Ds, I will re-rig the amp and do some experimenting with operating points. I have a variac so I will be able to rewire the existing transformer for higher voltage and use the variac to adjust the Vds and do some experimenting.
The LTSpice results for MR's resistive load operation point used in choke loading at 10W had 3rd harmonic slightly higher than the 2nd harmonic, and also had a lot of higher order harmonics. The other operating point gave THD that was a bit higher but the 2nd harmonic was dominant.
In-situ measurements will be done when I get the 2SK180Ds and hopefully I will then be able to decide on Vds and Iq.
hello Ben,
have you build this 2sk180 with choke?
what is the result?
thanks.
Working slowly, just started building the monoblock chassis from scratch. I need to have the chassis built so that I can mount the 2SK180 to the heatsink. I decided not to temporarily reuse the existing L'Amp chassis for the experimenting since it would require reworking to fit the 2SK180. This will save me time in the long run although it does delay the operating point tests.
The heatsinks are purchased. They are 300mm x 210mm 0.18C/W from the diyAudio Store, and will be one per channel.
It could be a couple of weeks or more before I start the tests. Building chassis from scratch takes quite a bit of time, especially since I am using only portable tools, namely hand power drill, drill guide, and taps. But this is part of my diy entertainment and fun during Covid times.
Another operating point candidate from LTSpice simuations is Vds = 34.5V Iq = 3.0A.
The heatsinks are purchased. They are 300mm x 210mm 0.18C/W from the diyAudio Store, and will be one per channel.
It could be a couple of weeks or more before I start the tests. Building chassis from scratch takes quite a bit of time, especially since I am using only portable tools, namely hand power drill, drill guide, and taps. But this is part of my diy entertainment and fun during Covid times.
Another operating point candidate from LTSpice simuations is Vds = 34.5V Iq = 3.0A.
Yes, single ended is easy to do. I will be reusing the bias supply from the 2SJ28 L'Amp - just flip the polarity. Since my Luminaria has low output impedance, no input buffer is required.
Meanwhile, the tunes are lovely with my BAF2105/Singing Bush, so there is no rush. I am taking my time.
Meanwhile, the tunes are lovely with my BAF2105/Singing Bush, so there is no rush. I am taking my time.
I agree! Wow! I don't have the audio vocabulary to describe subtle changes or all the parts that make up the whole, but I do know when something affects me. That system is (to use your word) marvelous!
Thank you again for your help, your advice, and for the great listening session and conversation. I listened to a few individual tracks last night, and I listened to Tea for the Tillerman 2 this morning to remember and compare in my mind.
There's obviously more to it than the amp, but I am looking forward to building mine. I've already got some sweet oil and paper caps on-hand.
Now to get Diana and try to learn. I've had my morning tunes and coffee
LOL! You know I am slow. Because I am a padawan, I have to be methodical while I learn. Big badaboom with these parts would make me .
I am trying not to solder, solder, solder, screw w/o absorbing some thought. I have been thinking about this for ages. I had thoughts put to paper, but I am still completing my construction notes and thoughts before I get the iron hot. I have PAGES. Some pieces.
PSU/Chassis Options
Seems that I can "get away" with a few options or go full on "proper" with the chassis and PSU etc. Maybe there can be some stages to the build.
For the PSU(s)
I need to build a new PSU for required voltage. Debating CLC (Inspired by Ben), CRC (standard I am familiar with), or using LT4320 similar to Chuck. I have boards etc. for all options, but I am undecided. I am trying PSUD, but I am still not fully capable. I'd need to buy chokes if going with CLC.
Bias supply - I have a few 18V 50VA Anteks. However, since I need to get new donuts anyway, why not get extra secondaries and save some space? I've lusted after some of those gorgeous Toroidys. However, I was inspired by "Uncle Bob's" gorgeous wooden build with separate chassis for dual PSU and stereo amp. If I go that route, can do it similar to his layout with the baby donuts in with the bias boards / amp chassis.
For the Chassis.
Custom. Separate PSU enclosure, stereo, or monoblocks.
Use what I have.
1) 5U/400 stereo - See if it can deal with heat for stereo perhaps w/o Schade, but probably not with Schade.
2) 5U/400 monoblocks (inspired by Asphalt) - Upper on one side. Lower on the other. Make proper heatspreaders across each section of the sinks to allow proper dissipation since only one device per smaller section of sink. Would not do this until I get Toxic Masculinity chassis (1 or 2), b/c Babel J2 must always have a home.
Wait for what is to come.
1) Toxic Masculinity. I am waiting to see if it is really more capable than 5U/400 for this application. I committed to try one.
2) Get 5U/500(s)
Overall build/circuit:
Lots of operating points in early posts were fascinating. It was interesting to look at the distortion profiles. I truly appreciate the work to conduct and post those measurements. I also absorbed Ben Mah's comments re: in situ changes, but I have to start with the basics.
I got both the Schade and Non-Schade versions b/c at the moment, I only have THF-51S. Still hunting for elusive 2SK77x.
Per mighty ZM "if you don't have 2SK77/2SK77B and you vary of compromises, just make Schade iteration ...... that one was more cunning from Pa than primary one (with 2SK77B) , meaning - it's easy when you have jewel in your hand , while its harder to make jewel from brick."
So, I should probably start with Schade, but that takes more oomph at 3A2 => HEAT. Plus, I haven't seen a Schade build yet. So, why not?!
Opposite side is that others have really enjoyed their non-Schade with THF-51s or similar, so that is my "easiest" starting point. It's the one I will probably go with to begin. I think I will see how heat for stereo at 2A2 (or so) in existing 5U/400 chassis and think more from there.
See... silly brain...
would make me . I am trying not to solder, solder, solder, screw w/o absorbing some thought. I have been thinking about this for ages. I had thoughts put to paper, but I am still completing my construction notes and thoughts before I get the iron hot. I have PAGES. Some pieces.
PSU/Chassis Options
Seems that I can "get away" with a few options or go full on "proper" with the chassis and PSU etc. Maybe there can be some stages to the build.
For the PSU(s)
I need to build a new PSU for required voltage. Debating CLC (Inspired by Ben), CRC (standard I am familiar with), or using LT4320 similar to Chuck. I have boards etc. for all options, but I am undecided. I am trying PSUD, but I am still not fully capable. I'd need to buy chokes if going with CLC.
Bias supply - I have a few 18V 50VA Anteks. However, since I need to get new donuts anyway, why not get extra secondaries and save some space? I've lusted after some of those gorgeous Toroidys. However, I was inspired by "Uncle Bob's" gorgeous wooden build with separate chassis for dual PSU and stereo amp. If I go that route, can do it similar to his layout with the baby donuts in with the bias boards / amp chassis.
For the Chassis.
Custom. Separate PSU enclosure, stereo, or monoblocks.
Use what I have.
1) 5U/400 stereo - See if it can deal with heat for stereo perhaps w/o Schade, but probably not with Schade.
2) 5U/400 monoblocks (inspired by Asphalt) - Upper on one side. Lower on the other. Make proper heatspreaders across each section of the sinks to allow proper dissipation since only one device per smaller section of sink. Would not do this until I get Toxic Masculinity chassis (1 or 2), b/c Babel J2 must always have a home.
Wait for what is to come.
1) Toxic Masculinity. I am waiting to see if it is really more capable than 5U/400 for this application. I committed to try one.
2) Get 5U/500(s)
Overall build/circuit:
Lots of operating points in early posts were fascinating. It was interesting to look at the distortion profiles. I truly appreciate the work to conduct and post those measurements. I also absorbed Ben Mah's comments re: in situ changes, but I have to start with the basics.
I got both the Schade and Non-Schade versions b/c at the moment, I only have THF-51S. Still hunting for elusive 2SK77x.
Per mighty ZM "if you don't have 2SK77/2SK77B and you vary of compromises, just make Schade iteration ...... that one was more cunning from Pa than primary one (with 2SK77B) , meaning - it's easy when you have jewel in your hand , while its harder to make jewel from brick."
So, I should probably start with Schade, but that takes more oomph at 3A2 => HEAT. Plus, I haven't seen a Schade build yet. So, why not?!
Opposite side is that others have really enjoyed their non-Schade with THF-51s or similar, so that is my "easiest" starting point. It's the one I will probably go with to begin. I think I will see how heat for stereo at 2A2 (or so) in existing 5U/400 chassis and think more from there.
See... silly brain...
did I wrote that?
oh Boy, I'm sometimes surprising even my self with my own Brilliance ........
Thank you, Dirk! I've read through that thread over the last several months.
I should have been more clear (who, me?). I haven't seen one or heard one in person.
I got to hear Botte's non-Schade version.
I thought I may try the Schade version due to ZM's quote above, and b/c it would be another type to compare locally. Getting an opportunity to A/B Schade and non-Schade could be fun.
However, I don't have enough aluminum (at the moment).
I should have been more clear (who, me?).
I haven't seen one or heard one in person. I got to hear Botte's non-Schade version.
I thought I may try the Schade version due to ZM's quote above, and b/c it would be another type to compare locally. Getting an opportunity to A/B Schade and non-Schade could be fun.
However, I don't have enough aluminum (at the moment).
Santa arrived for me, too!
I need to get a Rawson rebuild done that is currently on the bench, then it’s time to build 2 singing bushes. One for me, one for a friend. My friend has the SITs, so I’ll need to mask up and meet up to get them.
I’m going to use a 5U/500, dual mono CLC PSU setup. I got handles for front and back of the chassis because I expect this will be a heavy one.
Looking forward to this build!!
I need to get a Rawson rebuild done that is currently on the bench, then it’s time to build 2 singing bushes. One for me, one for a friend. My friend has the SITs, so I’ll need to mask up and meet up to get them.
I’m going to use a 5U/500, dual mono CLC PSU setup. I got handles for front and back of the chassis because I expect this will be a heavy one.
Looking forward to this build!!
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Can't wait to see those!
When you finish the builds, I'd be very interested to see your heatsink temps. Based on Gianluca's data, I'm stabbing at ~50C on the fins and ~55C at the hottest part of the sink. Error should only hopefully be ~5C either way. That's a SWAG with one device per heatsink section, guessing ambient temp of 22C, a 5U/500, and 125W dissipation per side.
Hey wait! Don't you need 5 channels to go with your 5 Iron????
When you finish the builds, I'd be very interested to see your heatsink temps. Based on Gianluca's data, I'm stabbing at ~50C on the fins and ~55C at the hottest part of the sink. Error should only hopefully be ~5C either way. That's a SWAG with one device per heatsink section, guessing ambient temp of 22C, a 5U/500, and 125W dissipation per side.
Hey wait! Don't you need 5 channels to go with your 5 Iron????