NTC is hot in operation
you don't need it in plastic block , near base plate
see my builds - it's always on well elevated pcb and with long legs
others are putting these in most substantial connecting blocks
rails are ok , for unloaded
when loaded , count on Vac x 1.25 , or so
you don't need it in plastic block , near base plate
see my builds - it's always on well elevated pcb and with long legs
others are putting these in most substantial connecting blocks
rails are ok , for unloaded
when loaded , count on Vac x 1.25 , or so
Except I am a big dodo.
I have 4 0R47 in parallel. It is amazing how frustration removed even my ability to count 
A new morning and a clear head for review. I have effective 0R1175. No wonder the sinks get so much warmer when set to 0V28 across the resistor => 2A5 Iq.I listened into the wee hours and have been listening for a few hours this morning. It sounds wonderful, and we are within thermal limits. Once I put it in the rack and put the feet on, I'm at ~52 C on the sinks and ~60 C on the packages. I left it on over night to get to highest temp. For the MOSFET, I just used the bolt on top to measure. Is there any concern with the higher Iq @ 2A5 or should I back it down to approximately 0V2 to achieve the original target of 1A8? I tried to look up and read some spec sheets, but once again... I was not successful.
It's been a great deal of fun. I hadn't picked up a soldering iron in over 25 years. I had no idea that from my first project in March to now, I'd have built 7 different DIY projects and completed 12 total builds. The bug bit so hard, I had to spread the illness. So, I had a group of people over for a WHAMMY build party. Next, some of them will build the Pocket Class A (aka Altoids) amps with me. Attempting to learn the electrical aspect has been rewarding, but clearly I still make even the most basic of errors. I'm still in the category of assembling Legos for adults. 😀 Online resources are great, but this old dog may go take a "real" class for some hands-on instruction.
In addition, I now have an opportunity to listen to some truly excellent amplifiers back to back, A/B or whatever term is best used and tweak for the best pairings. Matching gear and seeing how the sound is affected has always been a fascination of mine, but I've never had the opportunity. Attempting to learn and understand the the different topologies is a bit complex for me at the moment. The next rabbit hole after I get my listening impressions noted will be to try some basic measurements. The discussion around the balance of 2nd to 3rd order harmonics and their relative phase has me fascinated. I'd like to see if there are any trends in what I hear and what I prefer relative to measurements.
I think I found some appropriate in-line fuse holders. Oddly, I cannot find any that bolt to the chassis base. Something like this seems like it would work well.
https://www.digikey.com/product-detail/en/mpd-memory-protection-devices/BF310/BF310-ND/8119220
@Cal3713 - thank you for the additional information on the motor caps! Given my recent goofs, I think I'm going to pause for a bit. Just when I think I understand something... 😕
@rhthatcher - great looking start! Yet another thing I need to learn. CRC vs. CLC and all the fun different ways to "just" get AC to DC cleanly.
itsallinmyhead - nice that your amp is singing. I expect a 3am session when mine are up and running. Cool to see the bug bit you too. I made ACA in December and since then have reworked a stack of Rawson builds and made 2 F5’s. Some for me, some for a friend. I hadn’t done a real build in about 20 years - 300B amps and a tube preamp back then.
Currently on the agenda:
2 SissySIT for me. (Active system, need 2)
F5 V3 turbo monos for a buddy
Technics SP10 Mk2 - waiting for plinth
Troubleshoot and fix Bryston mono bloc for a buddy
Monster custom tube high gain high power bass amp for a musician buddy - I expect this will be a couple year effort. Ideally carvin x100b preamp + ampeg Svt in one big heavy box. To get what he wants will take lot of back and forth and prototyping.
My wife commented the amp chassis and box stack in my basement area is a bit out of hand.
Currently on the agenda:
2 SissySIT for me. (Active system, need 2)
F5 V3 turbo monos for a buddy
Technics SP10 Mk2 - waiting for plinth
Troubleshoot and fix Bryston mono bloc for a buddy
Monster custom tube high gain high power bass amp for a musician buddy - I expect this will be a couple year effort. Ideally carvin x100b preamp + ampeg Svt in one big heavy box. To get what he wants will take lot of back and forth and prototyping.
My wife commented the amp chassis and box stack in my basement area is a bit out of hand.
@ItsAllInMyHead
nothing wrong with dgky No. 283-3062-ND , or 36-3537-ND , if you put some plastic under ( old X-Ray sheets are good enough, use 1 layer for first one , 4 layers for second 🙂 )
and
regarding current - think of that poor tiny mosfet you're having down , and go back to 1A8
that would be 1A8 x (0R47/4) = 210mV
nothing wrong with dgky No. 283-3062-ND , or 36-3537-ND , if you put some plastic under ( old X-Ray sheets are good enough, use 1 layer for first one , 4 layers for second 🙂 )
and
regarding current - think of that poor tiny mosfet you're having down , and go back to 1A8
that would be 1A8 x (0R47/4) = 210mV
Thank you! I'd expect you'll be up for a while. 🙂 I started in March when a friend sent me a little headphone amp affectionately called the "Coaster" along with two sets of boards, some basic tools and a soldering station. He just had a hunch that I'd enjoy the build. I sourced the parts and assembled both. I learned a bit about how to follow the traces on a board to a schematic. When they first fired up, I was hooked! Then I got a bunch of extra parts for friends to build some of those. Little did I know that NO ONE wanted to do SMD work. So, I still have a stack of parts. I find it fun... with HUGE jeweler's glasses.
Then that same friend mentioned the WHAMMY. So, I built one and was astonished how someone with my lack of skills could get an amp of that quality up and going. So, I got 3 more kits and had some friends build them under my "expert" 😉 and watchful eye. They all had working amps at the end of the day.
After that, I got hooked on Crack...
Then, I thought I'd take on a "real" project. I was going to build two of Tom Christiansen's DG300Bs. I sourced the majority of the parts and got the boards, but two things intervened. First, Tom provided wise guidance that it may not really be the best first speaker amp project for a person at my skill level. Second, he generously offered to sell me his personal amps. I'll get around to building at least one of them as a headphone amp once I build skills.
With no speaker amp to build... I found this great community and the idea behind First Watt. I was immediately hooked by the opportunity to build a set of common PSUs and chassis to swap out amp boards. After a TON of reading, I picked the M2x for my first build. Again, I was simply blown away by the amp. I still have a great deal of fun swapping out the input stages.
I had the Aleph J on my list to build, so that came 2nd. The Aleph J stole the chassis from the M2x.
I was intrigued by the Pocket Class A amp. So, I built two of those and got a bunch of extra parts and boards after I built one and listened to it. My 2nd has already been "stolen" by a friend. We'll build more.
Now the SissySIT and trying dual mono.
That's a fantastic list of work! I haven't done vinyl in years, but...
Next up:
I have the boards for the F4 and F5 built, but not installed or tested. I am anxious to try the F4 with two separate pre-amps and also with the DG300Bs. I've heard wonderful things about the F5.
I need to get my other chassis converted to dual mono, get both chassis and PSU combos "identical" and leave them alone. I may try the motor caps.
I am looking at pre-amps. I'm trying desperately to get to Burning Amp, but schedules are tight. I'd like to see what's going on with the workshop.
Yeah... mine is very supportive, but now she thinks I can fix a Nespresso machine... 😀
Don't want to take ZMs thread too far off topic, but I really appreciate the camaraderie of the community here.
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ZM - So sorry for delay.
I backed off the Iq yesterday to 1A8 (this time properly done).
It takes some time for the temp to become stable, so I waited several hours before final tweaks and put it back into the main system.Temps on the sinks are ~46 C. SIT is ~50C on the device. The big washer on the MOSFET is ~50C. No problem for the temperature.
I got some brackets from local store today to re-mount the donuts vertically. I'll do a trial fit tomorrow. I can also rewire the fuses and fuse holders later this week when parts arrive. I should have it in the "final" configuration and pretty by the weekend. Maybe then I can learn about motor caps.
Singing beautifully. 😀
Finally got back to it. Setting IQ on the first channel. Things look pretty stable, but have climbed very slowly, from 160mV to 182mV over the past 20 minutes. If the table shakes or I put my hand on the lid I start moving around. Is that normal?
Found out the problem from last week. The IQ trimpot needs to be zero'd from pins 1 - 2. I was setting it from 2-3, then measuring that in circuit to confirm. Because 2 & 3 are tied together, they show basically the same low resistance as I was supposed to be getting, but the trimpot was actually set at full resistance instead of zero.
Found out the problem from last week. The IQ trimpot needs to be zero'd from pins 1 - 2. I was setting it from 2-3, then measuring that in circuit to confirm. Because 2 & 3 are tied together, they show basically the same low resistance as I was supposed to be getting, but the trimpot was actually set at full resistance instead of zero.
well , if your soldering is good , then shaking can't do much to Iq 
personally I know how much eyes can be wide when doing something outa comfort area for first time ...... being there numerous times , majority of them being situations where I really wasn't qualified enough ..... but I'm still alive , and I really burned just some peanut parts , not counting few AVOmeters , when I was youngggggggg
all that , just to cheer you up ; if you feel uncomfortable from any reason - just power it off and write here
setting SissySIT is same as setting F5 , or F7 , or BA3 FE - it demands time and patience , and you'll be rewarded 🙂
personally I know how much eyes can be wide when doing something outa comfort area for first time ...... being there numerous times , majority of them being situations where I really wasn't qualified enough ..... but I'm still alive , and I really burned just some peanut parts , not counting few AVOmeters , when I was youngggggggg
all that , just to cheer you up ; if you feel uncomfortable from any reason - just power it off and write here
setting SissySIT is same as setting F5 , or F7 , or BA3 FE - it demands time and patience , and you'll be rewarded 🙂
P1 pre-set help !!
will link this in post #1 too
"0R" means - set it to damn Zero Ohms!!!
🙂
will link this in post #1 too
"0R" means - set it to damn Zero Ohms!!!
🙂
Attachments
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will link this in post #1 too
I have to laugh.
0R is zero ohms. It looks like "or," like you are giving a choice.
Rush
Just to increase confidence, I soldered my second set of boards yesterday, double checked every solder joint right after I made it to ensure that things were flowing well. Got to see everything except the mosfet since it was soldered while on the heatsink. After soldering, I checked with the old boards to confirm all parts were in the right place. No problems on any boards.
Strangely, my new right channel board is showing the exact same behavior as the old one. A short upon startup. I didn't copy, just started fresh, so I'm having trouble imagining where the issue might be. Currently DMM beeping around.
Strangely, my new right channel board is showing the exact same behavior as the old one. A short upon startup. I didn't copy, just started fresh, so I'm having trouble imagining where the issue might be. Currently DMM beeping around.
I found some pictures of your in #1005 and #1014
care to post some more , in situ?
diodes - be sure that you didn't mixed plain ones with zenners
blind as I am , I'm always positioning proper part of text on diodes up , when bending legs
so I can read "48" or "voltage" when they're on pcb , if I awake in a middle of the night , having nightmare about mix-ups
care to post some more , in situ?
diodes - be sure that you didn't mixed plain ones with zenners
blind as I am , I'm always positioning proper part of text on diodes up , when bending legs
so I can read "48" or "voltage" when they're on pcb , if I awake in a middle of the night , having nightmare about mix-ups
@Cal3713 -
Great news re: finding the issue!
FWIW, I originally got the value to set at around 160 with the sinks sitting warming for about an hour. Then once I started bumping up, it took about 2 hours for it to stabilize until I could get it to sit still at a value +- 5 mV. Once I got it to sit still, I came back after a couple hours, make a final tweak to the offset and put the lid on overnight. When I came back in the morning, the Iq had bumped up a wee bit, but nothing to be concerned about, and the offset was still 0mV +- 5. So, I left it alone. If I take the lid off, then both the offset and Iq shift for me even if it's only for a minute. So, I generally figured out how much movement in the pot would result in a change... I'd pop the lid, the Iq would go down in my case, but I'd move the pot a wee bit in the proper direction to bump the value. Then I'd let it sit until it quit rising.
So, yeah.. in my case it was very temp sensitive and moreover, it took hours to stabilize. I did not see it change if I bumped the table etc.
Great news re: finding the issue!
FWIW, I originally got the value to set at around 160 with the sinks sitting warming for about an hour. Then once I started bumping up, it took about 2 hours for it to stabilize until I could get it to sit still at a value +- 5 mV. Once I got it to sit still, I came back after a couple hours, make a final tweak to the offset and put the lid on overnight. When I came back in the morning, the Iq had bumped up a wee bit, but nothing to be concerned about, and the offset was still 0mV +- 5. So, I left it alone. If I take the lid off, then both the offset and Iq shift for me even if it's only for a minute. So, I generally figured out how much movement in the pot would result in a change... I'd pop the lid, the Iq would go down in my case, but I'd move the pot a wee bit in the proper direction to bump the value. Then I'd let it sit until it quit rising.
So, yeah.. in my case it was very temp sensitive and moreover, it took hours to stabilize. I did not see it change if I bumped the table etc.
Currently uploading via my phone which is slow for some reason. Optocoupler is always upperleft dot towards the middle cutout on the silkscreen, right?
