or sit. or lean.
when I was in grade 8 we had a "practical" maths project assigned. I built a simple mechanical adding machine. didn't work.
one chap built a truss bridge section out of toothpicks. spanning between two stacks of books the test was to lay a brick on top.
before class a quick demo for a few of his friends worked a treat. but in front of the whole class the brick caught in his hand as he was laying it on the truss... and the whole structure buckled spectacularly.
wot larks!
when I was in grade 8 we had a "practical" maths project assigned. I built a simple mechanical adding machine. didn't work.
one chap built a truss bridge section out of toothpicks. spanning between two stacks of books the test was to lay a brick on top.
before class a quick demo for a few of his friends worked a treat. but in front of the whole class the brick caught in his hand as he was laying it on the truss... and the whole structure buckled spectacularly.
wot larks!
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I pondered standing on my amp last night, but thankfully there was no one around to hand my drink to while eagerly saying "Hey, Watch this!"
Never thought such an analysis would show up in the forum . . . @birdbox on the verge of sizing members, discussing slenderness, and unsupported lengths
Must be a structural engineer. 🙂
Although strictly speaking, weight and mass are two different things. 🤓
Although strictly speaking, weight and mass are two different things. 🤓
Ben Mah found the marble in the oatmeal! You get to drink from the fire-hose! (obscure movie reference)
I don’t really get to do real engineering in my job so I guess it was like an old retired hunting dog that hears the sudden flutter of pheasant while out on a walk and all the memories come flooding back. I was looking at my little amazing F5m Redux amps last night while they were singing some tunes as I pondered how to design a fan shroud/speaker stand…..Then, all of the sudden memories of my junior level structures course came rushing back to me. I must have blacked out, because when I came to I had posted this wild long post about column buckling. At least I was finally able to use the MS Visio software that I paid for a decade ago. I'll tighten it up next time and try to stay on point. Back to pondering a 3D printed speaker stand design to sit atop the Redux.
Apologies for the distraction.
I don’t really get to do real engineering in my job so I guess it was like an old retired hunting dog that hears the sudden flutter of pheasant while out on a walk and all the memories come flooding back. I was looking at my little amazing F5m Redux amps last night while they were singing some tunes as I pondered how to design a fan shroud/speaker stand…..Then, all of the sudden memories of my junior level structures course came rushing back to me. I must have blacked out, because when I came to I had posted this wild long post about column buckling. At least I was finally able to use the MS Visio software that I paid for a decade ago. I'll tighten it up next time and try to stay on point. Back to pondering a 3D printed speaker stand design to sit atop the Redux.
Apologies for the distraction.
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I like these ‘hedgehog’ versions. More fun ways to enjoy these wonderful amps.
If there happens to be a need to spin a new version of the PCB, I would respectfully request support for gate stopper resistors in front of the output Mosfets. While the standard IRF parts are Ok without gate stoppers, the high transconductance parts that I have come to prefer benefit from having gate stoppers to adjust the voice of the amp.
If there happens to be a need to spin a new version of the PCB, I would respectfully request support for gate stopper resistors in front of the output Mosfets. While the standard IRF parts are Ok without gate stoppers, the high transconductance parts that I have come to prefer benefit from having gate stoppers to adjust the voice of the amp.
While we're on the wish list....
An option for a footprint compatible board for a preamp: Maybe FE2022 inclusive of pcb edge mounted `volume knob' and interconnects to the main amp board to share the supply but with some independent filtering. Stacking a preamp and F5m Redux would be groovy. One per speaker and a little commercial DAC would make for an excellent system for small rooms/desktop etc.
An option for a footprint compatible board for a preamp: Maybe FE2022 inclusive of pcb edge mounted `volume knob' and interconnects to the main amp board to share the supply but with some independent filtering. Stacking a preamp and F5m Redux would be groovy. One per speaker and a little commercial DAC would make for an excellent system for small rooms/desktop etc.
@BeardyWan , why not get a price quote from a PCB layout specialist? There are a few on diyAudio. Then you can sell boards at a price which pays for both fabrication and all layout fees after a total of (?10?) / (?25?) / (?50?) boards are purchased. This offers the advantages that (a) the project starts right away; you don't have to wait an unknown and perhaps very long time for the board to appear. (b) the board contains exactly the mechanical and electronic features which YOU desire; you don't have to put up with someone else's inelegant choices. (c) it opens the door to additional boards afterwards. Perhaps a DAC. Perhaps a battery board with intelligent recharging, capable of running the power amplifier and two other boards. Perhaps a wifi receiver & stripped down streamer.
The sky's the limit; dream big.
The sky's the limit; dream big.
Hi Mark,
I am deeply grateful to others that have contributed the fruits of their labor. I have greatly enjoyed Nelson's previous hedghog, likewise your VRDN, Nelson's ACA, M2, FE2022 & Stasis, Michael's MoFo, Wayne's headphone amp etc.
I do not have the skills to do as you suggest and if I did I would not attempt to develop a new product that profits from the hard work of others. My opinion was given free of charge. Most importantly, I am not asking someone else to do something for me. Your post is a continuation of a theme and every now and again we all need a little encouragement. I am sure I am not alone in my appreciation.
I am deeply grateful to others that have contributed the fruits of their labor. I have greatly enjoyed Nelson's previous hedghog, likewise your VRDN, Nelson's ACA, M2, FE2022 & Stasis, Michael's MoFo, Wayne's headphone amp etc.
I do not have the skills to do as you suggest and if I did I would not attempt to develop a new product that profits from the hard work of others. My opinion was given free of charge. Most importantly, I am not asking someone else to do something for me. Your post is a continuation of a theme and every now and again we all need a little encouragement. I am sure I am not alone in my appreciation.
No skill required! Just say, "Hey Prasi, could you please put Nelson Pass's FE 2022 (or a different choice you like better) on a PCB which can be mechanically stacked with F5m Redux? How much would that cost and how long would that take?"
Then find a way to spread the PCB layout fees among the first (N) builders. All skilled technical work is performed by others; the job of project organizer and "show runner" is simply to recruit the needed contractor(s) and handle the funds.
Then find a way to spread the PCB layout fees among the first (N) builders. All skilled technical work is performed by others; the job of project organizer and "show runner" is simply to recruit the needed contractor(s) and handle the funds.
@N Brock - My brother's F5m Redux(es) have been sitting stable for almost 24 hours now and playing beautiful music. I can't thank you enough for allowing me to buy an early version. You got me out of a pickle. 
For those that are curious about my experience building the F5m Redux -
My experience - I've built over 25 DIY electronics projects over the last 5 years or so. I still don't have a firm grasp on circuits, but I'd consider myself a reasonably decent solder slinger. Nelson allowed me to purchase an early kit as a kindness to help me out of a crunch. My thoughts are unsolicited and unpaid, but I thought they were worth sharing. He may or may not change things about the design.
My impressions -
Thanks again, Nelson!!!
For those that are curious about my experience building the F5m Redux -
My experience - I've built over 25 DIY electronics projects over the last 5 years or so. I still don't have a firm grasp on circuits, but I'd consider myself a reasonably decent solder slinger. Nelson allowed me to purchase an early kit as a kindness to help me out of a crunch. My thoughts are unsolicited and unpaid, but I thought they were worth sharing. He may or may not change things about the design.
My impressions -
- The build:
- Start to finish in about 5 hours. (Open box to playing test music on both channels). I took breaks along the way. I try to take :15 every hour and/or at break points / obvious spots. So, total time spent was about 4 hours net... I didn't set a timer.
- I didn't have one of Nelson's incredible video guides, but the schematic was crystal clear, and the silkscreen on the boards was absolutely ideal, IMO. No questions
- For those that are curious about SMD soldering. The pads are 'generous' to say the least. There are a variety of components with various profiles. I soldered with a typical iron, and I used a 1/16" chisel tip (I generally use a smaller tip for most of my SMD work if I use an iron). I used two diameters of solder, but anything but the largest diameters on my bench would have been fine. (Sidebar - I think solder diameter may be often overlooked as a key factor to success). The feedthrough caps need careful inspection (as do all parts) to ensure all four pads are properly soldered with no bridging, and careful cleaning of any flux/residue/goo/detritus between those pads is advised. Tucking the tip up against the chokes/diodes shouldn't give anyone a hard time. I placed the chokes by hand vs. using tweezers. The DPAK MOSFETs shouldn't be an issue.
- The quality of parts and ease of assembly to standard pitches is fantastic. No fancy schmancy lead bender needed to get a clean build.
- OKAY... the black shows all flux and dust... ALL of it. That's both a plus and a minus.
- The aesthetic:
- Soooooooo Cool.
- I will change / modify two things most likely.
- I'll remove the stickers from the fans.
- I'll probably come up with some "single box, single AC cord" PSU solution. 4 AC cords will be a minor issue for the use case. It's so minor that I'm not going to worry about it for several months at least. One of the reasons I needed these was a time crunch. Can't spend any more time on it for now.
- I'd LOVE true 5-way binding posts, but I completely understand that they may not work. My banana plugs won't work. So, I swapped speaker cables for testing. Not sure how it would work with spades... I may try it. The relative light weight of the units allows them to be pushed around a bit. With that said, these went in behind a much larger (physically) amp. Most people likely won't be using the same cabling.
- I may put on some heavy feet using the handy dandy standoffs provided as a base.
- Testing - I didn't do any. I biased it up, nulled the offset, and played some music. I was in a time crunch; I had no reason to think it wouldn't work; and this is likely what may people will need to do b/c they don't have test gear.
- The sound:
- All caveats apply from previous... I can't hear... we are all different... our systems and rooms are all different...
- It sounds like an F5m, which is to say... IMO, it almost has no right to sound this good.
- The summary - It's one of the coolest projects I've built. Value for dollar / time spent is unprecedented in my experience. Everyone needs these. When people ask me what projects to consider, it will be VERY high on my list.
Thanks again, Nelson!!!
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I've got an IEC cord splitter on the way. I need to test it before I can recommend anything specific, but it's a potential option to reduce the number of outlets required.
I use banana plugs in my setup and AFAIK these are 5 way binding posts. Do your plugs not fit at all, not stay in, or something else?
Fantastic! They'll likely be welcome additions.
It could be that I have odd banana plugs. I tried two types of banana plugs that work well with multiple other sets of binding posts (very secure fit). Not ruling anything out on my end re: assembly, but they seemed simple enough. The symptom is that the plugs don't insert very deeply (comparatively speaking), and they will slide out with a gentle bump.
I just checked a few different plugs against my bin of binding posts and found some combinations that do the same. Some of the binding posts have a burr where the cross hole is. Removing the burr with a drill bit or reamer allowed the previously non-fitting plugs to seat fully. Something to add to my checklist when packing kits!
If built per schematic, the F5m (including Redux version) has about 16.5 dB of gain. 1 volt in will give 6.7 volts out.