Love your companies work Aiyima, but please don't go down the Fosi path of promoting this op-amp rolling nonsense.
I understand what you feel, but these companies are not scientific promotion bodies, they have to make money, by granting this possibility they can offer a well-designed product and at the same time attract all the users who like to mess with the design without this creating a disadvantage for usLove your companies work Aiyima, but please don't go down the Fosi path of promoting this op-amp rolling nonsense.
JSmith
True... but then I've pointed out this aspect to Fosi before (fallen on deaf ears), that they should be careful directing customers to modify a product that is meant to be "fit for purpose" to start with and what implications this may have for them in certain countries (depending on the local consumer laws).attract all the users who like to mess with the design
Anything electronic that I released back to a customer that had been MODed, had a mains transformer tampered with or was not 100% like new in safe operation was released as, "For test purposes only." That way I was not responsible for any further operation of that unit that the customer was responsible for. The insurance can be nulled and voided in some circumstances I was advised although I don't know the specifics of that. So selling gear that is made to be tampered with by non experts seems like a recipe for disaster llegally speaking.True... but then I've pointed out this aspect to Fosi before (fallen on deaf ears), that they should be careful directing customers to modify a product that is meant to be "fit for purpose" to start with and what implications this may have for them in certain countries (depending on the local consumer laws).
JSmith
The opposite of the seal/sticker with “no user serviceable parts inside”Anything electronic that I released back to a customer that had been MODed, had a mains transformer tampered with or was not 100% like new in safe operation was released as, "For test purposes only." That way I was not responsible for any further operation of that unit that the customer was responsible for. The insurance can be nulled and voided in some circumstances I was advised although I don't know the specifics of that. So selling gear that is made to be tampered with by non experts seems like a recipe for disaster llegally speaking.
As @solderdude stated clearly a couple of days ago regarding OP amps and the OP amp peripheral circuitry the ratio of the peripheral resisters and reactance too if used in the OP amp circuit peripheral determines the gain of the circuit. Not the bare OP amp total specification for maximum gain. So OP amps can be swapped without changing the gain of the OP amp circuit once it is calibrated from the factory by selecting peripheral parts for the OP amp circuit gain level. It's amazing that this is the way and is what makes it OK for newbies to experiment with OP amp rolling and test drive different OP amps. I had somehow forgotten this information from my OP amp education comprised of a couple of months of study decades ago. Thank you @solderdude for bringing me back up to speed on such fundamental theory of OP amps. It is safe to swap the OP amps providing the rest of the PCB circuitry is not tampered with.I’m more concerned that making the general amp design safe to operate with a range of op amps migth not be the optimal design for,the circuit at hand ?
Not always there could be bandwidth concerns it can get unstable and oscillating, maybe due to parasitic coupling or peripheral components that would not bother one amp but do bother some other op amp ?As @solderdude stated clearly a couple of days ago regarding OP amps and the OP amp peripheral circuitry the ratio of the peripheral resisters and reactance too if used in the OP amp circuit peripheral determines the gain of the circuit. Not the bare OP amp total specification for maximum gain. So OP amps can be swapped without changing the gain of the OP amp circuit once it is calibrated from the factory by selecting peripheral parts for the OP amp circuit gain level. It's amazing that this is the way and is what makes it OK for newbies to experiment with OP amp rolling and test drive different OP amps. I had somehow forgotten this information from my OP amp education comprised of a couple of months of study decades ago. Thank you @solderdude for bringing me back up to speed on such fundamental theory of OP amps. It is safe to swap the OP amps providing the rest of the PCB circuitry is not tampered with.
This is a power amplifier board taken directly from a mobile phone. We guarantee that no components will be modified.
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But they have advantages. I am looking for a more powerful desktop amp to drive my KEF R3. Naturally the Apollon Audio et al amps are way bigger due to the internal PSU. They dont really fit on my desk but having a PSU on the ground would be OK.
Yes, you are correct.Not always there could be bandwidth concerns it can get unstable and oscillating, maybe due to parasitic coupling or peripheral components that would not bother one amp but do bother some other op amp ?
This is an aspect of OP amps that I am not thoroughly educated in anymore. I have forgotten details and some theory of OP amps. But it makes sense that anything different can differentiate them apart from one another. OP amps are a intriguing device in that they are so immune to bad stuff, reject bad stuff and can do so many functions just by swapping out peripherals and changes in the circuit layout. I need to get a proper OP amp theory textbook and refresh everything in my mind before I get to talking fancy like a expert on OP amps. Maybe @solderdude if he has the time can follow up with this thread and get us properly informed.Also nois can differentiate them ?
Thank @AIYIMA:GUO for sharing. Love those smd caps on through hole footprints. Got the inspiration from the max thread?This is a power amplifier board taken directly from a mobile phone. We guarantee that no components will be modified.
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Yes, the slew rate and the resulting upper frequency response of the OP amps was/is cool and maybe is more so for some of the more fluent newbies that OP amp roll. They expect better highs and stuff I guess. I think it's cool that they get their feet wet in electronics by OP amp rolling Aiyima amps like the A70 and checking out the PCBs and whatever they do when inside there mucking about. I think they need to start somewhere and even if it's fantasy it's still getting experience.Was it not fad of using high speed op-amp for tinkering ?
If I'm not wrong, those 4 capacitors are signal coupling capacitors, not decoupling capacitors for the main power source. Using x7r in that position maybe not good ideaThank @AIYIMA:GUO for sharing. Love those smd caps on through hole footprints. Got the inspiration from the max thread?
There are quite some unpopulated parts, are you aiming at v2 with some additional feature?
Thanks!
Nice pictures, who much will be this A70 without the power supply?This is a power amplifier board taken directly from a mobile phone. We guarantee that no components will be modified.
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You've clearly never seen the bricks they use here in Cambodia!Calling it so, does a complete dis-service and is a slur against an actual brick