You've also said that the amplifier board has spectacular, world-beating PSRR.
Driven by a typical, ordinary, run-of-the-mill, power supply, your amp ought to perform better than all other amps. Surely DIYers can build a typical, ordinary, average power supply supply board themselves! -- and thanks to the PSRR of modulus86, get better performance than all other amplifiers. How delightful: your amp is supposed to be the most forgiving of supply imperfections, in the whole world.
Those potential buyers who timidly believe, or desperately fear, that your $50 PCB layout is vitally necessary -- can simply clone it: monkey see, monkey do. And save substantial money. You've provided photo documentation of the front side, and the traces + planes of the not-visible reverse side are obvious, because there are only 10 components on the entire board. I'm sure lots of people have carefully saved the .jpg file in case it disappears from the diyAudio website or from your paypal sales page.
Naturally a must-replicate believer can insert electrically-neutral jukes and jives, which drastically change the visual appearance but not the electrical performance. It isn't difficult to invent such maneuvers; just ask yourself "what would my great-grandma, the jury foreman, think" and then act accordingly. The most obvious baby step would be to modify the density of the pours/fills. Power86 rev1.0 chose density=100%; grandma would find 75% to be shockingly different, especially if it employed a repeating cell with hexagonal (rather than Manhattan) symmetry.
10 boards for $37, versus one board for $50, would not appear to be a difficult decision. Particularly for the second through tenth buyers, who are merely purchasing unwanted excess inventory from the guy or gal who laid out the replacement PCB and paid for the first ten boards.
Driven by a typical, ordinary, run-of-the-mill, power supply, your amp ought to perform better than all other amps. Surely DIYers can build a typical, ordinary, average power supply supply board themselves! -- and thanks to the PSRR of modulus86, get better performance than all other amplifiers. How delightful: your amp is supposed to be the most forgiving of supply imperfections, in the whole world.
Those potential buyers who timidly believe, or desperately fear, that your $50 PCB layout is vitally necessary -- can simply clone it: monkey see, monkey do. And save substantial money. You've provided photo documentation of the front side, and the traces + planes of the not-visible reverse side are obvious, because there are only 10 components on the entire board. I'm sure lots of people have carefully saved the .jpg file in case it disappears from the diyAudio website or from your paypal sales page.
Naturally a must-replicate believer can insert electrically-neutral jukes and jives, which drastically change the visual appearance but not the electrical performance. It isn't difficult to invent such maneuvers; just ask yourself "what would my great-grandma, the jury foreman, think" and then act accordingly. The most obvious baby step would be to modify the density of the pours/fills. Power86 rev1.0 chose density=100%; grandma would find 75% to be shockingly different, especially if it employed a repeating cell with hexagonal (rather than Manhattan) symmetry.
10 boards for $37, versus one board for $50, would not appear to be a difficult decision. Particularly for the second through tenth buyers, who are merely purchasing unwanted excess inventory from the guy or gal who laid out the replacement PCB and paid for the first ten boards.
Thank you for the recognition. I do my best to provide value to the DIY community. A prominent example is my writings on the LM3886 available on my website: Taming the LM3886 - Get the most out of your chip amp.
In addition, I have quite a few threads in the Chipamp Forum, including:
LM3886 Point-to-Point vs PCB
LM3886 Thermal Experiment (with data)
This in addition to lengthy individual contributions, such as, Post #66 on stability in the "Improving the LM3886" thread. This post, was the main motivation for me to get the Taming the LM3886 page going.
I enjoy getting theory and practice to converge and result in stellar circuits. I also enjoy the customer interactions and value their feedback. I think it's pretty clear what I'm about and how I deliver value, both to my customers and to the DIY Audio community as a whole. People are free to disagree with my approach, pricing, and whatnot. As long as my customers are happy and the boards keep moving off the shelf and into envelopes, life is good.
~Tom
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I spent A LOT of time in my previous life conducting DBLTs .. many on Golden Pinnae as HiFi Reviewers are mostly self declared Golden Pinnae.
I haven't tested every Golden Pinnae in the known universe but nearly 2 decades of conducting DBLTs leads me to wager a lot of money that Golden Pinnae are deaf 😱
If you get one to do two DBLTs one after another without changing anything, the Golden Pinnae will give completely different results for the two.
A corollary is that nearly all HiFi reviewers (with very few exceptions) are MUCH less perceptive than the Man in the Street. And the Woman in the Street is significantly better than the Man in the Street. 🙂
So if your girlfriend, wife or mother says, "I don't like this new one as much as the old" you'd better pay attention.
It is useless to rely on the opinion of a Golden Pinnae to design anything.
But for someone involved in commercial HiFi production, you have to take this in your stride. For Golden Pinnae, you repeat VERY loudly that all your stuff is hand carved from Unobtainium by Virgins. 🙂
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Mark Johnson, I'm sure your plan of action will result in good sounding clones .. IF ... you have your PCBs designed & fabricated by virgins from Unobtainium. I'm not sure Seeed Studio have the expertise. Virgins are thin on the ground 🙂
@Mark. No one is being forced to buy the PSU board. But for those who want to assemble something that just works it IS good value. DIY builders come in all shapes and sizes and skill levels after all. I think choice is always good.
For the record I have now ordered 4 mod-86 boards for my active apogee centaur minor project. As a cloth-eared old git do not expect flowery reviews tho...
For the record I have now ordered 4 mod-86 boards for my active apogee centaur minor project. As a cloth-eared old git do not expect flowery reviews tho...
Where were you 10 years ago when I started to go down the rabbit hole of boutique resistors, fly-wire mods and completely untested electronics in audiophool, confirmation-bias listening sessions. 😡
- opamp swap, high-speed opamp oscilating = more "air" (just like Tom has warned!)
- uncompensated rising response full range driver = better "detail"
- fly-wire mod to DAC ps, poorer bypassing = wider "realism"
- homemade digital cables, poorer SPDIF, more jitter = less "digital glare"
Oh, what a maroon I was!
What a maroon!
...
Oh wait, you probably were here and explaining ... but I wouldn't listen! 😱
😛
Thanks again to people like you and Tom.
Especially Tom, because as you pointed out, he's patient.
And, as just evidenced, professional.
Happy Holidays,
Cheers,
Jeff
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Spice simulations, are you serious?
Loop gain lacking? So I gather you think that high open loop gain feedback amplifiers sound good?
Making assumptions about earth loops and galvanic isolation. Well you know what the the saying is about making assumptions.
This thread reminds me of an old engineering joke. (Yes, such things exist.) A factory assembly line breaks down, and nobody can fix it, so they call a consulting engineer. He bashes it with a hammer and it immediately starts working again. The boss is delighted until he receives an invoice for $10,000 for consulting services. How can this guy charge 10 grand to hit something with a hammer?! So he writes back to ask for an itemised invoice. The new invoice arrives:
One blow with ball peen hammer: $0.50
Knowing what to hit: $9999.50
Of course you can get 10 boards from Seeed Studio for $37, and of course you can beat on the assembly line with a hammer yourself, but will it work?
One blow with ball peen hammer: $0.50
Knowing what to hit: $9999.50
Of course you can get 10 boards from Seeed Studio for $37, and of course you can beat on the assembly line with a hammer yourself, but will it work?
If the DIYer who lays it out does a competent job, sure. Supposing the Modulus amplifier's PSRR really is as good as tomchr claims; then the power supply PCB is not at all critical. Just lay it out using standard power supply layout practices, perhaps following Nelson Pass PSU board layouts as examples, or perhaps following the parts placement and topside layout shown in the photo of Tom's PCB here in this thread. National Semiconductor's AN-1849 shows a power supply PCB layout for an audio power amp; it may offer some layout ideas too.
DIYers who have the confidence to lay out their own printed circuit board, may be motivated to consider alternatives and save themselves some money. Those who lack this confidence, can either buy an excess board from the confident guy/gal's ten-lot, or they can pony up the $50 for tomchr's competently laid out PS board.
Mark,
I think you're beating a dead horse here. Tom can charge whatever he wants for his product and services. (The Mod-86 offering looks perfectly reasonable to me.)
I'm confident the majority of DIYaudio.com'ers interested in this thread and his products/services can make a valid value judgement and that they understand the various alternative options.
My goodness.
Dave.
I think you're beating a dead horse here. Tom can charge whatever he wants for his product and services. (The Mod-86 offering looks perfectly reasonable to me.)
I'm confident the majority of DIYaudio.com'ers interested in this thread and his products/services can make a valid value judgement and that they understand the various alternative options.
My goodness.
Dave.
well this is a thread selling a composite amplifier with high open loop gain and superlative measured performance. Not a thread about if high feedback sounds worse than low or no feedback. You clearly prefer the sound of a different type of amplifier to this. Fine by me and if you are happy with your current amplifier good for you. But I like the measurements and the engineering put into this amplifier. I know it has been designed to perform so I am pretty sure I will love the sound.
I think you are more likely to find kindred spirits elsewhere on the forums.
Ah sorry, apparently I need to check my sarcasm detector. Further difficulty there would be a grave affront to the gods of snark. 😉 Yes, if Tom wants to boost sales by assembling and getting into the high street it'd probably have to be a separate brand and a rather different website.
I wonder of the level of hearing impairment in Golden Pinnae, perhaps from listening too loud; IIRC some of Harman-Kardon's data shows those folks tend to score speakers differently, though with 80% of scoring in sighted tests being attributable to factors other than sound quality the approach is a mite problematic to start with.
Heh, you might know this already but equivalent SBLTs are an old recording engineer fallback for when a job has a Golden Pinnae as a producer. Letting the sliders sit on the mixer as tweak after tweak is requested can make both people happy; the producer random walks themself into a state of satisfaction with the music and the engineer winds up with something they can bear to put their name on.
Naw, I've only been on DIY Audio for 5.5 years. 10 years ago I'd just begun thinking about biwiring and passive horizontal and vertical biamps; it'd be another year before I started to get my head around damping factor requirements created by driver and cabinet energy storage and the cabling problems created by audio amplifiers' lack of remote sense.
Anyways, you're welcome and thanks for the thanks.
Quite. Mains, chassis grounding, transformers, cable shields, ground lift circuits and whatnot are amenable to modified nodal analysis like any other electrical circuit. Given the complexity of the space trying to gain insight into how things work whilst avoiding tools designed to provide just that is a remarkably awkward approach. One can build stuff and measure it too, a certain amount of which is required. But Spice is attractively fast and free compared to the careful differential probe setups needed to get good data without trouble from the measurement equipment's own grounding and CMRR limitations. (Just don't get carried away with it; be sure to read the .subckts for any device models used to assess whether their internal connections to node 0 are compatible with the sim you're running. Nearly all analysis can be done with simplified loads where this isn't an issue.)
You'd need to quantify high and provide an application. Not sure how much background you have in this area but Bruno Putzey's arrival at 18MHz as a basic minimum GBP for unity gain, first order, Miller compensated operation where sound in = sound out is desired is pretty reasonable. There's also some discussion from posts 129 to 137 in this thread on why paying attention to other parts of the playback system is desirable when increasing loop gain.
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I have to add, that having looked more closely at the THAT1200 spec sheets and the penny dropping that this gives almost optimal balanced performance from an unbalanced source for $6, I feel this should be part of any system. I will certainly be adding balanced inputs to my preamp on the next revision using these. I don't necessarily need it, but the peace of mind is well worth the cost.
I expressed that very same opinion, in post#454:
Maybe not; I think there might be quite a few DIYers who've only built boards at OSHpark or PCBexpress, and who are not yet familiar with some of the low cost alternatives. Seeed isn't even the cheapest; they're just the vendor whose pricing is easiest to copy-and-paste.
I honestly think it came as a surprise to some readers, that they can get ten PSU PCBs for $37, including shipping, if they perform the layout themselves. But now that it's been stated, quoted, and commented upon, this simply becomes another well-known option to choose from. Informed DIYers can make up their own mind.
Hi Tom,
Any chance you will have pre-built units for sale? I have soldered a little in my day, but last time I tried to do an entire board, it did not go so well...
Any chance you will have pre-built units for sale? I have soldered a little in my day, but last time I tried to do an entire board, it did not go so well...
Yeah, there are good reasons pretty much nobody in pro audio uses unbalanced interconnects---TR rather than TRS connections are normal in pedals but are usually wired pseudodiff. In DIY there's no reason I can see to use RCA->RCA either. If you're trying for the last 0.3dB of DNR or some other metric there are reasons not to use the 1200 (how many gnat farts are there per dB?) but it is an excellent cost no object default. And pretty well the only instrumentation topology amplifier on the market that's a good fit for audio use---the AD8421 is probably the next best option but Tom's measurements in post 384 show the 1200 clobbers it on CMRR.
I suppose I should point out power amps are both where the most current is pulled and where the lowest transformer turns ratios are found. So, in home audio where usually everything's on the same power strip or at least the same mains circuit, the largest differences between components' ground potentials occur at power amps. Hence their inputs typically have the highest CMRR requirement in the system and there's necessarily less return on the investment elsewhere. For example, way back when I was using a CD player and a preamp I thought I heard a difference between RCA->RCA and RCA->XLR between them (only unbalanced analog out on the player) but didn't obtain statistically significant discrimination.
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Dear friends,
Talk about price is just a waste of yours and Tom's time 🙂) he puts his time and efford to build M-86. You are always free to build your own desing or buy alternative diy\commercial products.
As a buyer, i am so apperciated his support. After sales, documentation is priceless for poor electronic knowledge users like me.
Regards....
Erkan
Talk about price is just a waste of yours and Tom's time 🙂) he puts his time and efford to build M-86. You are always free to build your own desing or buy alternative diy\commercial products.
As a buyer, i am so apperciated his support. After sales, documentation is priceless for poor electronic knowledge users like me.
Regards....
Erkan
If you don't like the prices Tom charges or what he is offering there is a new concept called the free market, including in DIY. Design your own stuff, start your own thread, give it away if you like. It is reasonable to ask on topic questions, impolite to keep beating a horse that was long ago declared dead by the Chief Engineer of this project.
I agree with the above, but if you look at SY's heretical preamp measurements The Heretical Preamp, p6 which are considerably less accurate than Tom's but nonetheless valid in showing the sort of noise that can be flying around a modern living room. He used a transformer, but it shows that the gains of a balanced input preamp are well worth having, if only for the peace of mind of a job done properly. That is worth more to me these days than any amount of audio fairy dust.
My machined from solid and silver plated fetish from my GSM radio days may take longer to get over...
I am sitting here with a wide smile on my face as I enjoy my morning coffee. I like the latest turn of the thread. In particular, I like the outpour of appreciation for my contributions and for my work. Thank you.
~Tom
~Tom