As it turned out I wasn't to be free long. I expected a bit more pain on days 3-5, but when my legs stopped working I went back. There were a few days of terrorizing the nurses once my legs stated working again. They had silly rules like don't get out of bed without help. Returning from the bathroom I was invited to sit in the recliner, which I noted they had just added an alarm to tell them if I got up. "I'll stay in bed since you alarmed the chair." "There's an alarm on the bed, too." "You realize that this means war! I'll sit in the chair." In 15 minutes I had disabled the alarm in the chair, got up and disabled the alarm on the bed. They were more than happy to clean me and the bed up if I couldn't hold it for the time between hitting the call button and them arriving, and somehow not understanding that at 55 years of age I am not interested in messing myself if it can be avoided.
Now I appear to be home for good. The repeat hospitalization means I won't get to spend as much time teaching my daughter the finer points of crimping and soldering, but my son made a surprise appearance. Spending time with the kids is a better thing to do, anyway.
Bones, that's always the hardest part for me. I have a hard time controlling myself while I feel good and don't notice that I have reached my limit until it is well past. Hoping to do better this time.
Will post progress photos as it happens.
Heh, talking to the choir here boss. I am also 55, and an orthopaedic surgeon (I do hip and knee replacements and have not done back surgeries since training) and as the saying goes, doctors make the worst patients. I have had a few smaller things done, ACL, rotator cuffs, and ankle fracture repair. I have frequently been back in the office that week, and doing surgeries again the next week.
I do see all sorts of people in my work, and see how different people recover from surgery. I find the self actuated, educated people, especially of the baby boomer time era, are very gung ho about bouncing back from surgeries. They are usually uncomfortable when not doing anything, and its the hardest thing for them to "sit around".
Hence my warning to you... Glad you are doing better. 6-12 weeks before you get frisky with your back I would imagine. Learn a new programming language or whatever.
Thanks for the concern Bones. Thought you might be more than just another concerned citizen. 
I took the picture in my avatar, so you pretty much hit the nail on the head with can't sit still.
I helped my best friend set up a pharmacological pain management practice to deal with patients who have failed other therapies and their primary care isn't willing to adequately manage their pain. It's funny how many refuse to do any PT or stretching, then way overdo it as soon as they reach a therapeutic dose of pain medications. I'm doing my best not to become one of those patients. My buddy figured that I was in for rods and screws by the look of my MRI (essentially no disc height and moderate to severe narrowing of the foramina with about every other bad thing from T12 to S1) Boy was I happy that my surgeon went with laminectomies to retain some flexibility, especially since I am already fused C3-C7 (bicycle accident). It feels like as the swelling goes down I should have essentially normal function. I've already lost my Frankenstein foot drop.
OK, enough health talk. I'd better get cracking on my AJ.
I took the picture in my avatar, so you pretty much hit the nail on the head with can't sit still. I helped my best friend set up a pharmacological pain management practice to deal with patients who have failed other therapies and their primary care isn't willing to adequately manage their pain. It's funny how many refuse to do any PT or stretching, then way overdo it as soon as they reach a therapeutic dose of pain medications. I'm doing my best not to become one of those patients. My buddy figured that I was in for rods and screws by the look of my MRI (essentially no disc height and moderate to severe narrowing of the foramina with about every other bad thing from T12 to S1) Boy was I happy that my surgeon went with laminectomies to retain some flexibility, especially since I am already fused C3-C7 (bicycle accident). It feels like as the swelling goes down I should have essentially normal function. I've already lost my Frankenstein foot drop.
OK, enough health talk. I'd better get cracking on my AJ.
Finally a little progress thanks to nothing interesting on television.
Keeping with the old school theme, the resistors in CRC are 25W chassis mount, 0R1. The most time consuming part was tapping the star ground holes. I have spare points just if needed.
The tapping time convinced me to just drill clearance holes to mount the resistors and fuse holders and use nuts and bolts. Another interesting aspect of drilling copper was that even with sharp drill bits there were significant burrs on both sides of the hole. Bad enough that I used a large handheld drill bit to deburr before drilling the next hole or the piece would not lay flat on the drill press table.
Hopefully tonight I will get some wiring completed. That or do the cap screw mod to the heat sinks so I can actually adjust the amp. The pots are inaccessible with the big cans so close to the board.
I'm thinking of mounting the mains connection, individual transformer fuses and CL-60 on a piece of no copper perf-board mounted to the transformer mounting bolts. The bridges will mount on the front panel. Still in the air whether single or dual. Anyone see any issues with this?
Claudio, I will make separate grounds for each channel if I have hum or noise problems. The bus bar is 0.125" thick, I suspect that most of the charging pulse current will be confined to a small area between the caps. I've had success with a similar arrangement on boards with a mere 2 oz copper thickness.
Keeping with the old school theme, the resistors in CRC are 25W chassis mount, 0R1. The most time consuming part was tapping the star ground holes. I have spare points just if needed.
The tapping time convinced me to just drill clearance holes to mount the resistors and fuse holders and use nuts and bolts. Another interesting aspect of drilling copper was that even with sharp drill bits there were significant burrs on both sides of the hole. Bad enough that I used a large handheld drill bit to deburr before drilling the next hole or the piece would not lay flat on the drill press table.
Hopefully tonight I will get some wiring completed. That or do the cap screw mod to the heat sinks so I can actually adjust the amp. The pots are inaccessible with the big cans so close to the board.
I'm thinking of mounting the mains connection, individual transformer fuses and CL-60 on a piece of no copper perf-board mounted to the transformer mounting bolts. The bridges will mount on the front panel. Still in the air whether single or dual. Anyone see any issues with this?
Claudio, I will make separate grounds for each channel if I have hum or noise problems. The bus bar is 0.125" thick, I suspect that most of the charging pulse current will be confined to a small area between the caps. I've had success with a similar arrangement on boards with a mere 2 oz copper thickness.
Attachments
That settles it, ZM. Dual bridges it is.
Thanks, Ron. Yeah, a lot of people consider anything north of White Plains "upstate". I'm 45 miles north of Albany. Snow yesterday, more snow forecast for tomorrow. What happened to Spring?
If you are looking for more power, I'd cascode the input jfets and add more output devices. Based on NP's comments in the F5T article, you should be safe with genuine 2SJ74s up to 30V. Higher than that you'll want to cascode. You may also want to double up the input devices to drive more outputs. See the Aleph2J threads.
Thanks, Ron. Yeah, a lot of people consider anything north of White Plains "upstate". I'm 45 miles north of Albany. Snow yesterday, more snow forecast for tomorrow. What happened to Spring?
If you are looking for more power, I'd cascode the input jfets and add more output devices. Based on NP's comments in the F5T article, you should be safe with genuine 2SJ74s up to 30V. Higher than that you'll want to cascode. You may also want to double up the input devices to drive more outputs. See the Aleph2J threads.
Well, this project stalled for quite a while. At least I have a good excuse. I recovered so well, I was able to enjoy the outdoors for the first time in years. I was able to hike and bicycle, so almost every free waking moment has been outdoors.
Cold weather and I don't get along well, so I spent some time on this today. I got the PSU wired up on the secondary side. It took a lot longer than I thought it would, but I'm just getting back to this. A couple bad crimps, and I need to buy some more quick release connectors, but otherwise, I am ready to set up the mains side wiring next session. Given the pace this afternoon, I guess another couple of sessions before I am ready to start testing and dialing it in.
16 gauge teflon wire looks a lot smaller than expected.
Cold weather and I don't get along well, so I spent some time on this today. I got the PSU wired up on the secondary side. It took a lot longer than I thought it would, but I'm just getting back to this. A couple bad crimps, and I need to buy some more quick release connectors, but otherwise, I am ready to set up the mains side wiring next session. Given the pace this afternoon, I guess another couple of sessions before I am ready to start testing and dialing it in.
16 gauge teflon wire looks a lot smaller than expected.
Attachments
Back from the dead. After nearly two years of gathering dust I finally returned to my Aleph J.
I modified the heat sinks to allow for removal from the outside since there's no way to reach the pots with the sinks mounted. I was surprised how sensitive the offset adjustment is even with a 25 turn pot. Two iterations and the first channel is stable at 3.5 mV offset and .415V across Source resistors. That gives a 31° C rise. I suppose I could go a bit higher, but why push in a relatively small case? I set R27 at 68K but got .56V on the Source resistors, that's 1.2A/
I'll clean up the wiring a bit after I finish adjusting, then burn in several hours before listening.
I modified the heat sinks to allow for removal from the outside since there's no way to reach the pots with the sinks mounted. I was surprised how sensitive the offset adjustment is even with a 25 turn pot. Two iterations and the first channel is stable at 3.5 mV offset and .415V across Source resistors. That gives a 31° C rise. I suppose I could go a bit higher, but why push in a relatively small case? I set R27 at 68K but got .56V on the Source resistors, that's 1.2A/
I'll clean up the wiring a bit after I finish adjusting, then burn in several hours before listening.
Attachments
Last edited:
Second channel set up, amp burning in. Looks like I got the bias set at maximum for these heat sinks. When I took the Variac out of the circuit the rails jumped from 22V to 25V. (I have a voltmeter that I've been meaning to add to the Variac, but didn't measure)
That calculates to 86W per channel. Overall average heat sink temperature is 55° C, with 60° C at the devices and bench temperature of 25° C.
Looks like I will be current limited to about 45W with my speakers' impedance dip to 6 ohms. Probably plenty for most listening.
Edit: Thanks to 6L6 for the build guide. Gave me the confidence to restart this project.
That calculates to 86W per channel. Overall average heat sink temperature is 55° C, with 60° C at the devices and bench temperature of 25° C.
Looks like I will be current limited to about 45W with my speakers' impedance dip to 6 ohms. Probably plenty for most listening.
Edit: Thanks to 6L6 for the build guide. Gave me the confidence to restart this project.
Last edited:
- Status
- This old topic is closed. If you want to reopen this topic, contact a moderator using the "Report Post" button.