I would avoid using any extra "soft-start" boards in one of Papa's Class A designs. They add unnecessary complication to the output signal and grounding system that frequently causes more problems than they are supposed to solve. Especially for newer builders. They also take up space inside the chassis that could be better utilized by other things. The worst offenders are the combination speaker protection and soft-start boards that require a separate power supply. Just don't.
The easiest and simplest way to implement a soft-start with the big transformers and PSU capacitor banks has been documented in many places, including the early articles on the PassDIY site for the Zen v4 amplifier. Within these forums, schematics may be found on the first page of the Aleph J illustrated build guide as well as the F6 Illustrated Build Guide. These are the same circuits used in amplifiers sold by FirstWatt, and they work quite well.
One does need to exercise care in selection of the thermistors as well as how they are connected to the power supply. The CL-60 is preferred for use in the ground-lift connection between audio ground and chassis, due to its 10 Ohm cold start property. The CL-70 thermistors are better to use for the inrush current limiting positions on the primary side of the power transformers. These present a higher initial resistance, and drop to a lower steady-state resistance during operation. For higher current amps, I use MS22-20005 thermistors. As the Aleph J can be set for pretty high quiescent current, the MS22-20005 is a good part to use.
The easiest and simplest way to implement a soft-start with the big transformers and PSU capacitor banks has been documented in many places, including the early articles on the PassDIY site for the Zen v4 amplifier. Within these forums, schematics may be found on the first page of the Aleph J illustrated build guide as well as the F6 Illustrated Build Guide. These are the same circuits used in amplifiers sold by FirstWatt, and they work quite well.
One does need to exercise care in selection of the thermistors as well as how they are connected to the power supply. The CL-60 is preferred for use in the ground-lift connection between audio ground and chassis, due to its 10 Ohm cold start property. The CL-70 thermistors are better to use for the inrush current limiting positions on the primary side of the power transformers. These present a higher initial resistance, and drop to a lower steady-state resistance during operation. For higher current amps, I use MS22-20005 thermistors. As the Aleph J can be set for pretty high quiescent current, the MS22-20005 is a good part to use.
I used the store slow start just like in 6l6's build thread for my BA3 build. All others I've built are per First Watt CL-60. A heavier part may be better, but I have a bunch of CL-60 on hand.
I didn't use the speaker protection that came with the slow start. It requires no separate power supply and was easier to wire that the dual CL-60 route.
Most importantly, it has worked perfectly for years.
Russellc
I was actually thinking towel on the table, to avoid parts bouncing onto the floor. But your point is also a good one!
OK, I've posted the next installment in the "noobs guide" blog that we're building:
Parts: The Rest of the BOM
Happy for any comments, suggestions, etc. We've got a link to a fully populated Mouser cart with (we hope) all the necessary parts for our simple, noobs Aleph J build. We'll try to keep it updated, since that sure is easier for a noob to use than building their own spreadsheet from the various BOMs out there.
Parts: The Rest of the BOM
Happy for any comments, suggestions, etc. We've got a link to a fully populated Mouser cart with (we hope) all the necessary parts for our simple, noobs Aleph J build. We'll try to keep it updated, since that sure is easier for a noob to use than building their own spreadsheet from the various BOMs out there.
Looking good. At a quick glance...
1. You mention wires twice (formatting)
2. In the BoM - you can choose to use all the same Panasonic 0R47 3W if you'd like for the PSU and amp board. Personally, I would.
3. In the BoM - you have male Fast-On type connections for the PSU. I assume those are for connecting the wiring from the bridges to the UPS. If so, you may choose to include your choice of female connector.
4. I would recommend looking at the methods for the ground lift mentioned in a number of threads and either adding one more CL-60 to the parts list or noting in the guide that you've chosen another method. IMO, I'd add one more CL-60 to the list.
5. Noob here too, but I don't think the cap you've noted as PSU C9 is for filtering. If it is to be used in the same position (C9) as noted in the PSU schematics, I think it is a safety cap to reduce the potential for sparks at turn-on / turn-off. However, I admit to being unsure. This isn't something I "know", it's just from my notes copied from the Aleph J thread.
6. There will be other attachment points to the chassis; the ground lift CL-60 if chosen and your safety earth and the toroid shield. You may also consider some ring or other type terminations for connections to your mains / toroid terminal block along with a few screws, nuts, and star washers (or your choice). It may help avoid a run to the hardware store.
Love the blog. I think it will help a lot of people.
1. You mention wires twice (formatting)
2. In the BoM - you can choose to use all the same Panasonic 0R47 3W if you'd like for the PSU and amp board. Personally, I would.
3. In the BoM - you have male Fast-On type connections for the PSU. I assume those are for connecting the wiring from the bridges to the UPS. If so, you may choose to include your choice of female connector.
4. I would recommend looking at the methods for the ground lift mentioned in a number of threads and either adding one more CL-60 to the parts list or noting in the guide that you've chosen another method. IMO, I'd add one more CL-60 to the list.
5. Noob here too, but I don't think the cap you've noted as PSU C9 is for filtering. If it is to be used in the same position (C9) as noted in the PSU schematics, I think it is a safety cap to reduce the potential for sparks at turn-on / turn-off. However, I admit to being unsure. This isn't something I "know", it's just from my notes copied from the Aleph J thread.
6. There will be other attachment points to the chassis; the ground lift CL-60 if chosen and your safety earth and the toroid shield. You may also consider some ring or other type terminations for connections to your mains / toroid terminal block along with a few screws, nuts, and star washers (or your choice). It may help avoid a run to the hardware store.
Love the blog. I think it will help a lot of people.
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To followup on ItsAllInMyHead's post, I too suggest the use of the Panasonic .47 ohm
resistor for both amp and PS boards. Or if you choose to use the Panasonic only for
the PS board, you can increase the order to 10 pieces to get the price break, which
is actually cheaper than 8 pieces.
Your R2/R4 (221K) CMF resister is strangely expensive. (They show up at over $7
CAD each). These are at least as good and significantly cheaper:
https://www.mouser.ca/ProductDetail/Vishay-Dale/RN55C2213FB14?qs=0x4sLrpp94K3t0PmacrEMQ==
https://www.mouser.ca/ProductDetail/Vishay-Dale/CMF60221K00FHEK?qs=UEmB0FaNOjj2fE3HYgZRJg==
resistor for both amp and PS boards. Or if you choose to use the Panasonic only for
the PS board, you can increase the order to 10 pieces to get the price break, which
is actually cheaper than 8 pieces.
Your R2/R4 (221K) CMF resister is strangely expensive. (They show up at over $7
CAD each). These are at least as good and significantly cheaper:
https://www.mouser.ca/ProductDetail/Vishay-Dale/RN55C2213FB14?qs=0x4sLrpp94K3t0PmacrEMQ==
https://www.mouser.ca/ProductDetail/Vishay-Dale/CMF60221K00FHEK?qs=UEmB0FaNOjj2fE3HYgZRJg==
Looking good guys! One suggestion, near the end of this most recent post, you say
"One last item: hookup wire. In order to wire your amp up, you'll need two different gauges of hookup wire (thicker for the 120v line voltage runs, thinner for everything else)"
I think you probably want the thicker gauge wire for both 120v (or 220-240, depending on your locale) input to the transformer primaries, and for the 18V (or 20V) output from the secondaries to the PS board. Probably from the PS boards to the V+ and V- pads on the Amp board too. You probably also want the heavier gauge wire for speaker ouputs (I.E. between the amp output and the binding posts).
So I might amend the above quoted sentences to say something like "thinner for line level audio input, thicker for everything else"
"One last item: hookup wire. In order to wire your amp up, you'll need two different gauges of hookup wire (thicker for the 120v line voltage runs, thinner for everything else)"
I think you probably want the thicker gauge wire for both 120v (or 220-240, depending on your locale) input to the transformer primaries, and for the 18V (or 20V) output from the secondaries to the PS board. Probably from the PS boards to the V+ and V- pads on the Amp board too. You probably also want the heavier gauge wire for speaker ouputs (I.E. between the amp output and the binding posts).
So I might amend the above quoted sentences to say something like "thinner for line level audio input, thicker for everything else"
If you’re an actual newb like me – as opposed to an amateur who mostly knows what she’s doing – sourcing what’s required for an Aleph J kit is a challenge. I suspect this is by design for those who’ve been building for decades and already have amassed leftovers from other projects, but for the newb there is no single page that highlights everything needed.
In fact, the store and forum pages allude to other pages for each of the necessary components (amp boards, parts, chassis, power supply + its parts), and each of those devolve into maelstroms of options and digressions, making it hard for the newb who hasn’t read 500 pages of post comments to source what’s needed.
As a writer and copy editor, I’m qualified to say that it’s a confusing, sloppy mess. But, with some help, I believe I’m finally on my way. And, as a self-proclaimed “actual newb,” I ended up buying a lot of extras and not-neededs. It’s not an efficient or economical endeavor, but hopefully my experience can light the way for others in the same boat.
As my parts packages arrived, I set them aside and sorted the boxes by category: I emptied all the resistors- and caps-labeled baggies into the amp board package, and all the other caps and related parts baggies into the PSU board package. Atop the laid-out-but-still-unassembled chassis sits the transformer’s box and back-panel parts list.
Finally, last night (9/29/20) after work, I cleared off my table, set up the soldering iron, and got to work.
I kept both the 6L6 Build Guide (BG) and DIY Aleph J Blogspot posts up for reference, but aside from a few notes, I found that just going by the BOM was easier.
Jumpers. I don’t actually know what a “jumper” is, technically speaking, but physically speaking, I used green-wrapped wire stripped from an old crossover and also the wire from an unused cement resistor. R6, R30, J1, J2. The BG at this step mentions potential “oscillations” and “compensating devices,” like I know what these are. I don’t. Another critique: update the photos to reflect the words! There are three R27s with a recommendation for soldering into the vertical one, but the picture (admittedly, but c’mon!) predates the recommendation.
"Pots." Okay, a word I know! Pot is a potentiometer, a resistor with adjustable values, I think? This is where the BG is both helpful and maddening. Great tip to adjust the value before soldering the pot in, but wtf does that actually mean? I own a digital multi-meter, but damned if I actually know how to use it. How does a newb adjust a pot? A friend pointed me to this Youtube video: “Use a Multi Meter to Check a Potentiometer.” I followed that and measured 45k ohm. I turned the blue pot’s silver screw 20 times to the right (clockwise) and got 40k ohm. I adjusted it 80 times to the left and got to 66k ohm. A few dozen more turns got me to 68.0-68.1k ohm. Yes, I kid, the blue 100k Bourns pot is a 25-turn screw – the same number of turns to my heart, rebuffed by one of the Bourns girls in high school (yes, actually). It’d be nice here for the BG to update the picture with a pot and not a jumper or resistor. Oh, one other thing. My blue 100k Bourns potentiometer mounts vertically on the amp board, which means it will sit horizontally when the board is attached to the heat sinks, meaning that the screw will hang into the chassis. I also don’t remember why I bought two blue Bourns 500 ohm pots.
Resistors. I had zero trouble with this part of the build, except for realizing that I never ordered the R28/29 .25w 3k-5k LED resistors and forgot that I substituted a .5w 1k resistor at R15 in place of a .25w 1k resistor that was sold out at Mouser and Digikey and backordered to Halloween. I wish the BOM or the BG offered more info on how to select between 3k and 5k for the R28/29 because I’m literally clueless on how to select this. I bought two 3k ones last night. Also, the BG is very correct to warn users to measure every single resistor. I once used 221R (R9-13) instead of 221k ohm at R2/4. Easy fix, no harm, and now I’m getting better at using my multi meter.
Tonight, I’ll start on the amp board diode and capacitors, as well as the other board’s parts up to this point while waiting on those resistors, which should arrive tomorrow (10/1/20). While I’m feeling better about parts selection on the amp boards, I’m still dreading the choices I’ll have to make with the PSU build inside my black 4U chassis.
In fact, the store and forum pages allude to other pages for each of the necessary components (amp boards, parts, chassis, power supply + its parts), and each of those devolve into maelstroms of options and digressions, making it hard for the newb who hasn’t read 500 pages of post comments to source what’s needed.
As a writer and copy editor, I’m qualified to say that it’s a confusing, sloppy mess. But, with some help, I believe I’m finally on my way. And, as a self-proclaimed “actual newb,” I ended up buying a lot of extras and not-neededs. It’s not an efficient or economical endeavor, but hopefully my experience can light the way for others in the same boat.
As my parts packages arrived, I set them aside and sorted the boxes by category: I emptied all the resistors- and caps-labeled baggies into the amp board package, and all the other caps and related parts baggies into the PSU board package. Atop the laid-out-but-still-unassembled chassis sits the transformer’s box and back-panel parts list.
Finally, last night (9/29/20) after work, I cleared off my table, set up the soldering iron, and got to work.
I kept both the 6L6 Build Guide (BG) and DIY Aleph J Blogspot posts up for reference, but aside from a few notes, I found that just going by the BOM was easier.
Jumpers. I don’t actually know what a “jumper” is, technically speaking, but physically speaking, I used green-wrapped wire stripped from an old crossover and also the wire from an unused cement resistor. R6, R30, J1, J2. The BG at this step mentions potential “oscillations” and “compensating devices,” like I know what these are. I don’t. Another critique: update the photos to reflect the words! There are three R27s with a recommendation for soldering into the vertical one, but the picture (admittedly, but c’mon!) predates the recommendation.
"Pots." Okay, a word I know! Pot is a potentiometer, a resistor with adjustable values, I think? This is where the BG is both helpful and maddening. Great tip to adjust the value before soldering the pot in, but wtf does that actually mean? I own a digital multi-meter, but damned if I actually know how to use it. How does a newb adjust a pot? A friend pointed me to this Youtube video: “Use a Multi Meter to Check a Potentiometer.” I followed that and measured 45k ohm. I turned the blue pot’s silver screw 20 times to the right (clockwise) and got 40k ohm. I adjusted it 80 times to the left and got to 66k ohm. A few dozen more turns got me to 68.0-68.1k ohm. Yes, I kid, the blue 100k Bourns pot is a 25-turn screw – the same number of turns to my heart, rebuffed by one of the Bourns girls in high school (yes, actually). It’d be nice here for the BG to update the picture with a pot and not a jumper or resistor. Oh, one other thing. My blue 100k Bourns potentiometer mounts vertically on the amp board, which means it will sit horizontally when the board is attached to the heat sinks, meaning that the screw will hang into the chassis. I also don’t remember why I bought two blue Bourns 500 ohm pots.
Resistors. I had zero trouble with this part of the build, except for realizing that I never ordered the R28/29 .25w 3k-5k LED resistors and forgot that I substituted a .5w 1k resistor at R15 in place of a .25w 1k resistor that was sold out at Mouser and Digikey and backordered to Halloween. I wish the BOM or the BG offered more info on how to select between 3k and 5k for the R28/29 because I’m literally clueless on how to select this. I bought two 3k ones last night. Also, the BG is very correct to warn users to measure every single resistor. I once used 221R (R9-13) instead of 221k ohm at R2/4. Easy fix, no harm, and now I’m getting better at using my multi meter.
Tonight, I’ll start on the amp board diode and capacitors, as well as the other board’s parts up to this point while waiting on those resistors, which should arrive tomorrow (10/1/20). While I’m feeling better about parts selection on the amp boards, I’m still dreading the choices I’ll have to make with the PSU build inside my black 4U chassis.
@13stoploss, I feel your pain! This is exactly why we're hoping to maintain a Mouser shared card that has all the parts you need (well, almost).
As for "jumpers", my intention was to use the leftover resistor leads, trimmed after soldering. But, like you, I wasn't sure if that would be OK, so will have to ask on this or the PSU illustrated build guide thread.
As the actual build sections start appearing on our DIY Aleph J blog, I hope you will let us know how we can make them even better. Your complaints have already helped me think about then (like showing how to measure and pre-set the pot to 1K). And hopefully you can warn us about the pitfalls you encounter, so we can avoid them!
As for "jumpers", my intention was to use the leftover resistor leads, trimmed after soldering. But, like you, I wasn't sure if that would be OK, so will have to ask on this or the PSU illustrated build guide thread.
As the actual build sections start appearing on our DIY Aleph J blog, I hope you will let us know how we can make them even better. Your complaints have already helped me think about then (like showing how to measure and pre-set the pot to 1K). And hopefully you can warn us about the pitfalls you encounter, so we can avoid them!
Further explanation of some of the notes in the BOM might be helpful as well. For example the notes regarding resistor choices for the LEDs. A noob would definitely not know how one resistor value or another would alter the brightness. Sounds silly but it’s something that would hang up a builder trying to proceed.
Hi fellow noobs, I have received my 6 aleph-j boards and 3 power supply boards for my 6 channel amplifier for my speakers. I have 2 600 VA toroidy audio supreme transformers on the way and am waiting on component orders to arrive. I am still deciding on how to house the amps. I am thinking of using 1 large case using a holton mains controller mounting the amp boards on 6 individual heatsinks with vertical fins and mounting two high quality fans underneath to blow air past heatsinks and out the top. What do you think is this achievable. All input is welcome.
I have put together some links to make it clearer.
DIY Audio Products – Holton Precision Audio
Conrad Heatsinks - Products [350mm x 151mm]
TTSAS0600 - SUPREME AUDIO grade transformer TSAS600VA - voltage to 50V - Shop Toroidy.pl
The idea being that I power 3 of the amps with each with own transformer and power supply. Hope this make things a bit clearer.
DIY Audio Products – Holton Precision Audio
Conrad Heatsinks - Products [350mm x 151mm]
TTSAS0600 - SUPREME AUDIO grade transformer TSAS600VA - voltage to 50V - Shop Toroidy.pl
The idea being that I power 3 of the amps with each with own transformer and power supply. Hope this make things a bit clearer.
If you are a noob, start with a stereo pair and experiment with that, then develop a plan after you gain some familiarity with the type of heat dissipation you'll be dealing with.
It's kind of a big investment what you are taking on, I would hate to see you overlook something then realize your idea won't work after you have already thrown a lot of money into it.
It's kind of a big investment what you are taking on, I would hate to see you overlook something then realize your idea won't work after you have already thrown a lot of money into it.
Thanks 2picoDumbs I was planning to build a three channel version at first as my speakers are three way with a marchand active xm44 crossover in saying that a 2 channel will be of no use to me. I have to buy the heatsinks any way it is just a question of to build two three channel or one 6 channel. My thinking is if I can supply enough forced air instead of natural convection to dissipate heat from the case it could work.