May-be the occasion to revisit your opinion ? SMDs are the standard industry, by now. So, they benefit for the most advanced technology. The reduction in path lengths they allow reduces the parasitic inductances and capacitances. Too, the reduction in size and the way they are tightly melted on the boards can reduce some mechanical vibration problems. As an example, ceramic caps are a lot better in SMDs.
BTW, i don't know what you mean by PRAT, me neither.
About the low medium lack of perfection, i believe an effect of the cap in the feedback path. I'm waiting for L.C. tries and reports about my proposal to get rid of them:
www.esperado.fr - VSSA with Diamond input and DC servo
http://www.esperado.fr/vssa-diamond/dvssa.php
Why should industry standards have a bearing on audio? It is the nickel end caps which protect most smd resistors which are the problem. There are a few types which are indeed suited for audio but after some research it became clear that a 800mW rating would be hard to source.
My experiment proves (to me at least) that nickel, or not, the SMD resistors on the FO boards sound much better than the non-inductive ww Mills. Sadly, the limited space made it impossible to try out resistors, proven to be good such as the 5W Shinkoh which i have at hand. Caddock MP930 would have been ideal...
Anyhow, what is on board seems to be plenty good.
The difference in values is hardly critical, but the specified Vishay part is one of the better sounding tantalum caps... As for the 0R i used an smd part just because i have plenty. A bridge would be fine, but bear in mind there is a track passing under one of the resistors...
Nope, 22 uF, the one specified in upgrade instructions. As mentioned wire can cause short ciruit to bypassing PCB track, so 0 ohm SMD part recommended.
This is exactly the reason why classic transformer & caps PSU-s are history for me.
Please note that my recommendation goes to SMPS1200A400 when speaking about the First One amplifier.
Because, on my opinion, audio is nothing special in electronic. Distortions witch can occurs in magnetic resistances, as an example, are measurable.
It is not because we don't know how to measure each and every aspects of the way a complex audio signal is reproduced, specially in the dynamic behavior, and that listening is a useful tool, that we have to be snake oil clients.
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I am very aware that the PS can make or break the final result and this is the reason i mentioned the specifics of my implementation.
I don't think i can reliably tell them apart. As one of my amps is still v1.2 it is easy to do an A/B and i may do it out of curiosity, but for me such tests are worthless. If a change in character cannot be heard immediately, without doing specific comparisons, i tend to ignore it. Per example, the change in the feedback resistor was very obvious and did not demand any listening effort.
It's a system related virtue, we always listen to the system in interaction with the room, so it depends. Anyway in my system they're like night&day.
SMD-s are the last discrete devices we would ever be able to use in DIY, next technology step would be reserved for industry productions only. Majority of today's SMD-s are so small or having so tight pinout layout that are unusable in DIY, still good portion of them very useful and quality parts, enabling short audio paths and low noise designs. So I'm not surprised that SMD resistors proved to be much better in feedback use than other types of resistors, same in other parts of amp's circuit.
It's a system related virtue, we always listen to the system in interaction with the room, so it depends. Anyway in my system they're like night&day.
Hi LC,
When v1.3 modules will be available ?
Thanks for the question hehe
Faster we'll sold out existing v1.2 batch, sooner v1.3 we'll be available on the market ... so buy more 😀
L.C.
After all these modules going round the world! I am also very curious about the builds and sound impressions.
Couple of hundreds modules out there and proceeding, mostly I get impressions and opinions on e-mail and private messages, nevertheless I'm sure some of them will post here too, especially impressions about v1.3.
Hi LC,
Do you have a hookup diagram for best performance on single SMPS for two FirstOne modules? If it was already discussed, can you please point me to the post #?
Thanks
Do
Do you have a hookup diagram for best performance on single SMPS for two FirstOne modules? If it was already discussed, can you please point me to the post #?
Thanks
Do