Found this:
What is the input impedance of the V3 Mono?
The input impedance for RCA is 25KΩ, and for XLR, it is 5KΩ
https://www.kickstarter.com/projects/fosiaudio/fosi-audio-v3-mono-power-amplifier/faqs
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Fosi Audio V3 Mono Amplifier Review
- Thread starter amirm
- Start date
Found this:
What is the input impedance of the V3 Mono?
The input impedance for RCA is 25KΩ, and for XLR, it is 5KΩ
https://www.kickstarter.com/projects/fosiaudio/fosi-audio-v3-mono-power-amplifier/faqs
BrooklynNick
Active Member
Thank you, really appreciate it. I reached out to Fosi directly and they said:
Balanced XLR input impedance: ≈ 22 kΩ
Unbalanced RCA input impedance: ≈ 20 kΩ
I guess I'll assume the newer numbers I got from Fosi are correct.
Why do you think a class AB is needed when the most powerful amplifiers are generally class D amps?
I'm curious
From things I've read regarding driving Magnepsn. A lot of people say the need an amplifier with high current capability.Why do you think a class AB is needed when the most powerful amplifiers are generally class D amps?
I'm curious
Ok, and why you think class D is weaker?
Purifi and Hypex class D amplifiers have 25A to start with ... and models with 40A also.
That's huge ... you need to invest thousands in class AB to have that current.
I'm just curious to know if anyone can measure what the Fosi V3 mono puts out. I never said I thought it was weaker.
If I remember, the fosi power supply is 10A ... not very high current.
But you can change it for any purify / Hypex class D with high current capability, class AB is pricier for that configuration (and that's what you ask for ... to buy a class AB)
Jost Buergi
Member
Amir did in his review. The max. output was a healthy 31A across the board, only a bit less into 2 ohms which is a nice bonus in itself.
Thank you for that
Thank Amir so much for the measurement! The V3 Mono is another amplifier co-created with members, following the V3 stereo amp. We would particularly like to thank @Toku, @ModDIY , @mike70 , @cyclo, and all the other members who have provided us with invaluable suggestions.
The V3 Mono is our first amp with PFFB implementation. During the period we sent the set to Amir for testing, our R&D team did not stop optimizing the V3 Mono, and we have now further improved its frequency response curve. Below is the chart for your reference.
View attachment 360736
The V3 Mono is currently in production, and it will be launched on Kickstarter on the 20th of this month. There will be very attractive discounts available then, and we hope you'll stay tuned!
Was there an answer on why this droops so much starting ~15-16kHz?
what would be the cause for the droop into 2 ohms? Is that a limitation of the main amp chip or is that due to the main capacitors or the power supply?
Hello everyone, after several decades I (61 years old) again a a little of my interest in hi-fi again and observe already since these for some time site, which I totally interesting - thank you very much thanks for that!!! And Here is my first question as a non-technician: Isn't the continuous increase in frequency response from 3K onwards also quite critical? It is only mentioned in passing. Greetings from Duisburg/Germany. Josef
staticV3
Grand Contributor
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Hi @josef119! Welcome to ASR.
It would be critical only if the increase in frequency response was audible.
In this case, the increase in response is so small that it's totally harmless and undetectable.
Turning the speakers by three degrees would have a bigger impact than what you see here.
It's important to look at the scale of the y-axis, not just the shape of the graph.
It would be critical only if the increase in frequency response was audible.
In this case, the increase in response is so small that it's totally harmless and undetectable.
Turning the speakers by three degrees would have a bigger impact than what you see here.
Hello staticV3, thank you very much for your quick reply! Is there a guideline as to what value the deviation should be considered critical? Best regards, Josef
staticV3
Grand Contributor
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That depends on the frequency range where the deviation lies.
In the mid band, a deviation of 2dB or more would concern me.
Here, where the deviation is focused at 10kHz and above, it could be 10dB or more and you may still not notice due to, among other factors, age related hearing degradation, a lack of treble content in the music that you listen to, or your loudspeaker's inability to even reproduce such high notes.
totti1965
Addicted to Fun and Learning
Hello @josef119,
Besides the fact that @staticV3 is totally right with his remarks,
I just want to mention, that the pfft implementation of the Fosi V3 is now perfect:
The frequency responce is now impeccable:
Post in thread 'Fosi Audio V3 Mono Amplifier Review'
https://www.audiosciencereview.com/...o-v3-mono-amplifier-review.53474/post-1934986
Also #14 in this thread
Grüße aus Bonn, von einem ähnlich „alten Sack“
thorsten
allaturca89
Member
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Hello everyone. I want to share with you how I dropped the temperature values of the V3 mono’s. I have a metal monitor stand and I placed the monos on the stand. I also put thermal pads between them, so the temperatures dropped seriously. And i put a heatsink on them for extra support. I hope it will be useful for you, stay with love.
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Ordin Aryguy
Member
I have been powering my (non-plus) original model LRS's with an Aiyima A07 for a couple years now. The Aiyima is decidedly lesser in total power than the Fosi V3 amplifiers are and I can honestly say that my speakers do not lack for power. I've never had a single issue ever with over-heating, clipping, noise, or anything else.
We live in wonderful times where Class D amplifiers are incredible performers, both audibly and in specs.
The Fosi will have zero problems with your LRS+'s, and vice versa.
I appreciate that, but everything I'm reading about the speakers suggests they like Class A/B amps, and sound better with them.
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