I was doing some soldering today and I got to the page in the build guide about semi conductors and I’m a little confused about the diodes. I have all 4 diodes here and I also have the CL-140 for TR1 . In the guide, George has a method for the FRED diodes where he bends them over one another but that seems like it would interfere with TR1 and D3.
Should I just mount the diodes on the underside like I did with the capacitors so I still have room for tr1 and d3? Or am I missing something?
There are no mentions of d3 d4 and tr1 in the build guide. I’m assuming because they are options for different builds. It also appears that the board in the photographs doesn’t even have these components at all.
Should I just mount the diodes on the underside like I did with the capacitors so I still have room for tr1 and d3? Or am I missing something?
There are no mentions of d3 d4 and tr1 in the build guide. I’m assuming because they are options for different builds. It also appears that the board in the photographs doesn’t even have these components at all.
Put them on the bottom, yes. Pat close attention to polarity lest you release the Magic Smoke on powerup.
Look at the lower left of my underside picture, right above the empty rectifier socket. That's where d3, d4 & tr1 go.
Again, pay attention to polarity on the diodes.
My error above.
Please look at this picture for the placement of d3. d4 & tr1.
https://www.diyaudio.com/community/threads/simple-simple-se-questions.125250/page-4#post-6906196
Please look at this picture for the placement of d3. d4 & tr1.
https://www.diyaudio.com/community/threads/simple-simple-se-questions.125250/page-4#post-6906196
I noticed you have a jumper across R1. I’m assuming that’s because you’re running a choke. I have a choke as well. Does that mean I need a jumper there?
diodes in! Hopefully no magic smoke.
tr1 in as well.
my board is mostly done- just waiting on u10 and u20
I can’t tell if posting all these photos is annoying or not. I found all the photos you guys shared here to be super helpful so maybe these can help the other tube builder wannabes out there
You are replacing R1 with the choke....so you can wire the choke wires right to the R1 terminals; Tony likely got it in the circuit in some other manner (but in the same location as R1)...look at the schematic.
Let's talk a little about the power supply....if you were using R1 you'd have a CRC (capacitor-resistor-capacitor) supply. You are replacing R1 with the choke (an inductor) so you will have a CLC supply. Refer to the book of Morgan for the difference....the CLC supply is a bit higher performance. Note that R2 is wired to ground in parallel with C1; this is a bleed resistor. It bleeds the charge stored in the caps down to zero volts when you shut off the amp.......you you don't get whacked with 450VDC when you turn it off and start working on it. Large uF caps can hold a charge for awhile...this resistor takes care of that for safety. It wastes a little power as heat when the amp is running but it's insignificant. The higher the resistance the less power it wastes but the longer it takes for the caps to bleed down. Always check that the B+ voltage has bled down before measuring or working on the amp, you can put your clip lead anywhere on the positive sides of those caps or at either end of the choke....other clip lead on ground. I think that 150K resistor should bleed the caps down in 30-45 seconds or thereabouts...again always check with your meter before diving in.
You can tweak your B+ voltage a little (you likely won't need to esp with KT88's) by changing the value of C1..less uf gives lower B+...
Your pictures are great....excellent quality....BTW you have one leg of a tube socket not soldered in the last pic above.
Up to you if you want choke on top or underneath.....I prefer my chassis to be low profile, so the chokes end up on top.
Consider leaving room for a motor-run cap.......with the board shifted to the right you likely have room for the motor-run. Also consider knocking out a "breadboard" chassis out of scrap or plywood or whatever. Get the amp up and running in that while you build your nitrocellulose lacquered spalted quilted dovetailed birdseye masterpiece (we are expecting nothing less) You may find that you can't squeeze everything in your final chassis...or perhaps the chassis is larger than needed, so a quick and dirty box isn't a bad idea. You can also slightly oversize your top plate if you are paranoid...cut it down on the tablesaw if needed.....easy enough.
I've been building a push-pull triode wired KT88 amp using George's universal driver boards, and my breadboard chassis is too small for both the choke and a motor run cap...so one of these days I'll get back to that project....playing with $15 class D boards lately. I'm figuring if I keep helping you perhaps it will motivate me to get back on that amp project...haha
One more thing..since your terminal connectors are also on the bottom and the silkscreen is on the top....triple check those too....you can refer to your paper doll cutout.
Let's talk a little about the power supply....if you were using R1 you'd have a CRC (capacitor-resistor-capacitor) supply. You are replacing R1 with the choke (an inductor) so you will have a CLC supply. Refer to the book of Morgan for the difference....the CLC supply is a bit higher performance. Note that R2 is wired to ground in parallel with C1; this is a bleed resistor. It bleeds the charge stored in the caps down to zero volts when you shut off the amp.......you you don't get whacked with 450VDC when you turn it off and start working on it. Large uF caps can hold a charge for awhile...this resistor takes care of that for safety. It wastes a little power as heat when the amp is running but it's insignificant. The higher the resistance the less power it wastes but the longer it takes for the caps to bleed down. Always check that the B+ voltage has bled down before measuring or working on the amp, you can put your clip lead anywhere on the positive sides of those caps or at either end of the choke....other clip lead on ground. I think that 150K resistor should bleed the caps down in 30-45 seconds or thereabouts...again always check with your meter before diving in.
You can tweak your B+ voltage a little (you likely won't need to esp with KT88's) by changing the value of C1..less uf gives lower B+...
Your pictures are great....excellent quality....BTW you have one leg of a tube socket not soldered in the last pic above.
Up to you if you want choke on top or underneath.....I prefer my chassis to be low profile, so the chokes end up on top.
Consider leaving room for a motor-run cap.......with the board shifted to the right you likely have room for the motor-run. Also consider knocking out a "breadboard" chassis out of scrap or plywood or whatever. Get the amp up and running in that while you build your nitrocellulose lacquered spalted quilted dovetailed birdseye masterpiece (we are expecting nothing less) You may find that you can't squeeze everything in your final chassis...or perhaps the chassis is larger than needed, so a quick and dirty box isn't a bad idea. You can also slightly oversize your top plate if you are paranoid...cut it down on the tablesaw if needed.....easy enough.
I've been building a push-pull triode wired KT88 amp using George's universal driver boards, and my breadboard chassis is too small for both the choke and a motor run cap...so one of these days I'll get back to that project....playing with $15 class D boards lately. I'm figuring if I keep helping you perhaps it will motivate me to get back on that amp project...haha
One more thing..since your terminal connectors are also on the bottom and the silkscreen is on the top....triple check those too....you can refer to your paper doll cutout.
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Since I'm sitting at an airport with some time on my hands....here are a few other pointers.....
The last power supply cap C2 is a low-impedance power reservoir for the amp when you have very dynamic music playing (loud bass lines, drum hits, etc) it's supplies the juice to the amp instantaneously (well almost
instantaneous) compared to pulling the power from the transformer. Wiring a motor-run cap in parallel adds additional uf to C2..ie larger reservoir. Motor run caps are "paper in oil" type and the have very low impedance (actually ESR...I'm no expert here) and can really provide the juice when needed. When you wire caps in parallel you add the uf's. These add to the "stiffness" of the supply, ie when instantaneous current demands go up the voltage doesn't sag trying to deliver the juice. It's the same idea as the giant beer-can sized caps that the car audio guys use. Typical music has a "crest factor".....a very small percentage of the time you need lots of power......for the rest of the time, the caps sit there loafing somewhat, although they are still smoothing an AC waveform into DC along with the resistor or choke....and the rectifier of course.
You can make a smoother DC waveform by adding RC stages to a power supply....so you can have a CLCRC or CRCRC or whatever...these make a cleaner DC voltage but drop more volts each time you add another RC stage. You can calculate the drop through each resistor using Ohm's law; consider googling "Ohm's wheel" and printing one and sticking it to your monitor...that's where mine is Earlier in this thread I posted your power supply sim..that's using Duncan amp's "PSUDII" free modeling software....it gets you close to reality for voltage, DC ripple, how happy your chosen rectifier will be, and models SS diodes or Vacuum tube rectifiers.
The last power supply cap C2 is a low-impedance power reservoir for the amp when you have very dynamic music playing (loud bass lines, drum hits, etc) it's supplies the juice to the amp instantaneously (well almost
instantaneous) compared to pulling the power from the transformer. Wiring a motor-run cap in parallel adds additional uf to C2..ie larger reservoir. Motor run caps are "paper in oil" type and the have very low impedance (actually ESR...I'm no expert here) and can really provide the juice when needed. When you wire caps in parallel you add the uf's. These add to the "stiffness" of the supply, ie when instantaneous current demands go up the voltage doesn't sag trying to deliver the juice. It's the same idea as the giant beer-can sized caps that the car audio guys use. Typical music has a "crest factor".....a very small percentage of the time you need lots of power......for the rest of the time, the caps sit there loafing somewhat, although they are still smoothing an AC waveform into DC along with the resistor or choke....and the rectifier of course.You can make a smoother DC waveform by adding RC stages to a power supply....so you can have a CLCRC or CRCRC or whatever...these make a cleaner DC voltage but drop more volts each time you add another RC stage. You can calculate the drop through each resistor using Ohm's law; consider googling "Ohm's wheel" and printing one and sticking it to your monitor...that's where mine is
Earlier in this thread I posted your power supply sim..that's using Duncan amp's "PSUDII" free modeling software....it gets you close to reality for voltage, DC ripple, how happy your chosen rectifier will be, and models SS diodes or Vacuum tube rectifiers.
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I do not have a jumper on R1. I am jumpering R14 & R24 because this particular SSE build is being set up for 6V6 or 6F6 finals. Much lower voltage than the model you are following.
I am using a choke. As such, you leave R1 unpopulated and connect the choke at the L1 pads up between C1 & C2.
Ahhhh I see!
Ohhhh I really hope it does!
thanks for sharing this bit. Part of why I’m building this thing is to learn what all this stuff actually does and info like this is super valuable. While my edcors showed up very early, my suggested reading materials are still in transit!
Great idea. I’ll start here.
I’m gonna try and put together a list of the last things I need from McMaster and mouser today.
Do those clip leads you shared with me play nice with any multimeter?
What kind of spec should I look for in a motor run cap? You’ve talked me into it.
Maybe I’ll post up my shopping list before I pull the trigger in case I have any compatibility issues
Search for "IEC 320"....screw in type.....with whatever other features you want .....switch....fuse. I prefer the switch being on the front, but having a redundant mains switch on the back has no downside.Sites like mouser are super intimidating to me because I search for something like “iec socket” and get 30,000 results and I’m like “oh god which one one of these is going to work and which one of these is going to give me some of that magic smoke I’ve heard so much about”
The IEC 320 type is the common one you see on power cords and PCs, etc.
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They are standard banana plugs........however most modern multimeters use safety insulted ones, and the actual banana socket may be recessed down in the meter or flush with the top surface of the meter.
Post a nice close-up picture of the lead sockets on your meter.....
Your meter has the safety style bananas.....and the female metal conductors in the meter are recessed (the top part of the connector is just plastic). Plain vanilla old fashioned bananas MAY work ...but on one of my meters with these recessed female conductors they barely contact and tend to fall out. The selection of grabber leads with the safety style bananas is a bit limited......here are some............Pomona is a quality brand......the grabbers on some of the cheaper brands tend to be....cheaper. Remember, you are measuring 450V+ so these are important.
https://www.digikey.com/en/products/detail/pomona-electronics/6248-12-2/737605 This one is 12" long...get a longer one
https://www.digikey.com/en/products/detail/pomona-electronics/6244-48-0/737588 This one is 48" long
https://www.digikey.com/en/products/detail/pomona-electronics/6244-48-2/737589
https://www.digikey.com/en/products/detail/pomona-electronics/6245-48-02/6125666 These appear to be a pair of the above
Note: these are all 300V rated.....but it's quite difficult to find 600V rated grabbers apparently.
All of my clip leads are 300V rated.....and I've had no issues....still way safer since you can measure high voltages 100% hands off with these.
I have all old style regular banana type....as mentioned some are tough to stick in some of my meters...I'm tempted to buy a set of these....these look really nice.
https://www.digikey.com/en/products/detail/pomona-electronics/6248-12-2/737605 This one is 12" long...get a longer one
https://www.digikey.com/en/products/detail/pomona-electronics/6244-48-0/737588 This one is 48" long
https://www.digikey.com/en/products/detail/pomona-electronics/6244-48-2/737589
https://www.digikey.com/en/products/detail/pomona-electronics/6245-48-02/6125666 These appear to be a pair of the above
Note: these are all 300V rated.....but it's quite difficult to find 600V rated grabbers apparently.
All of my clip leads are 300V rated.....and I've had no issues....still way safer since you can measure high voltages 100% hands off with these.
I have all old style regular banana type....as mentioned some are tough to stick in some of my meters...I'm tempted to buy a set of these....these look really nice.
The super-cheap $7 HF multimeter has really short bananas..so these will work with the old fashioned non-safety style clip leads, like these:
https://www.digikey.com/en/products/detail/pomona-electronics/3782-36-02/736657
Most of mine are that style....and they work great. The fancy leads above should also work with the HF $7 meter.
Keep in mind that the clip leads will come in handy for many other motorcycle/car/house activities when you need a meter.
https://www.digikey.com/en/products/detail/pomona-electronics/3782-36-02/736657
Most of mine are that style....and they work great. The fancy leads above should also work with the HF $7 meter.
Keep in mind that the clip leads will come in handy for many other motorcycle/car/house activities when you need a meter.