good to see you back in action

@namitkanojia9791

9 ай бұрын

Hello vipin bhai. Do you have any lm3886 for sale. Please do let me know.

Great to see you again John, cool stuff, cheers man.

Glad to see you back.

welcome back my friend.. It's nice to hear your voice. My friends, to whom I recommend your videos, rediscovered class A amplifiers with your explanations. Thanks for your sharing..

@iikatinggangsengii2471

6 ай бұрын

i call rca 'coaxial' back then, not exactly wrong but corrected by electricity shop owner

@iikatinggangsengii2471

6 ай бұрын

its bcs the asus spdif coaxial out use rca

The TPA3255 Datasheets says the Chipamp has a gain of 21.5dB. That means the opamps are providing that extra gain. So the opamps are not used as a Unity Gain opamp, they are providing gain, not only on the V3 but also on any of the other TPA3255 amplifiers from Fosi, Aiyima, etc.., except Topping PA5 which implemented PostFilter Feedback and that causes a reduction around 6-7dB of Gain, at the benefits of 6-7dB higher SINAD, and also its output inductors from Coilcraft or Wurth make a huge improvement on SINAD, as TI itself proved on the report called "SLAA701A LC Filter Design", and "SLAC736 - TPA3251 Inductor Study", where they tested like 20 different inductors and determined which inductors were the best for the TPA325X family amplifiers.

Thanks John! Nice video!

I really love this channel

Hi John ... Nice video ... good information. Confirms my own testing. The TPA3255 chip is fixed gain at 26.5 DB as you discovered. This leads to a fun situation where you have a comfortable volume going on the 32 volt supply then without adjusting anything you plug in the 48 volt supply and _nothing changes_ ... I've had more than one complaint about this from people expecting big exciting things to happen and they just don't. What the 48 volt supply gives you is some extra headroom before clipping, but don't expect a big change in audio quality. The input on this chip is designed for Pro-Audio levels of about 2 volts RMS. Some home-use DACs and CD players can produce that much signal, but regular signals like TV RCA outputs and External USB sound cards will never clip this amplifier on the 48 volt supply. Also it should be noted that, while I agree the 48 volt supply is simply unnecessary, it does not cut out on musical content. Even on brick walled CDs with about 3db of dynamic range the average power drops significantly. If you are only clipping on occasional peaks, with 3db of dynmaic range it's about half (65watts) with 10 db DR it's all the way down to about 20 watts on 4 ohms... and the power supply can handle that much easily.

@shaolin95

3 ай бұрын

This depends on the usage. For TR devices like Shakers buttkickers etc..the moment I switched to the 48v my bk mini lfe started to bottom as the amp as finally able to push the very low leve frequencies that the BK couldn't handle but had no issues with the 36v

@Douglas_Blake_579

3 ай бұрын

@@shaolin95 It's far more likely the amp was clipping on the 36v supply and when you plugged in the 48, you got added headroom, the amp no longer clips and now it's overdriving your ass shakers.

@Cesar-dt5tn

Ай бұрын

So with one is better for home use ( apartment) , 36 or 48v ? Tks

@Douglas_Blake_579

Ай бұрын

@@Cesar-dt5tn It's not about the use case... It's about the amplifier itself. The TPA3255 chip can handle 48 volts, but it starts getting very hot... in fact, dangerously so. The cooling solution in these small amplifiers is not up to the task of keeping the chip cool. At 48 volts you need a much larger heat sink and forced air cooling (picture something like a CPU cooler) to get full power from it. The hard part for people to understand is that no matter how hot the heatsink (in this amp, the case itself) gets, the chip is going to be hotter. With poor cooling solutions that temperature difference can be a killer. In fact, I've often seen situations where the heat sink and casings are cool while the chip itself is roasting near it's thermal limits because the cooling solution is not taking heat off the chip. In experimenting with a number of these amps using TPA3255 chips in really tiny enclosures with limited air circulation, about the maximum safe voltage is in the 36 to 40 volt range. Higher voltages end up producing more heat than the cooling solution can get rid of and then the chip ends up getting really hot, goes into a thermal panic and then shuts off to protect itself. That is ... there is a good reason why these amps usually come with 32 or 36 volt supplies. Since 40 volt supplies are not readily available, I end up recommending 36 as the maximum safe voltage for these little amps. 36 Volt supplies at 5 and 6 amps are easy to get from the online vendors and can be had for very reasonable prices. Be aware that most home listening happens at about 1 or 2 watts per channel. With music having about 20db of dynamic range that can hit 40 watts on peaks, but for most listening it won't get much over 30. With the 32 volt supply you will get 50 very clean watts per channel on 8 ohms and about 95 on 4. With 36 volts that jumps to 75 and 140 ... So it's not like you're somehow missing out on anything.

@Cesar-dt5tn

Ай бұрын

Hi Douglas! TKS a lot for your attention and contribution for Fosi buyers! Please, do you know If Ayima sells good volt supplies? With 36v 6A we still have a clean audio with Fosi V3 like 32v 5A? TKS again and regards!

Thanks for the effort. This amp should be more than capable to drive the last 2 channels of my 11-channel 4-ohm AVR (the rear heights), as it only has 9 powered. 50-75W/channel should be plenty with the 48V 5A supply. My only complaint about the amp is the lack of a dedicated power switch, so that I can set and forget the volume (and it does not mess up my 7.2.4 level settings I work hard to get correct). Since it costs less than $100, I'll just open it up and add my own toggle switch.

Interesting, I've just picked one of these up with the 48v supply. Running 6ohm speakers with it, I'm very happy with the performance. Now I'm thinking I could have saved a few pounds and just got the 32v version 😁

I think that it would be really interesting to see what that thing would do at the maximum recommend voltage on the datasheet, and enough current to make it give full power with both channels driven. The test you did on one channel with the bigger power supply was quite impressive, though.

@Douglas_Blake_579

7 ай бұрын

I wouldn't be taking that up to 51 volts. A lot of the caps will be rated for 50 or 25 volts depending on their positions in the ciruit.

Hello John, so to produce 30V RMS at the output one would need 1.5V RMS as input signal. The problem is music signal is -12 to -20dB lower than pyre test tones (1kHz 0dbFS). This means we really need a preamp. What are your thoughts?

Yeah clipping is a issue with my watt hungry 4 ohm magnepan lrs+, thus clipping on loud passages. Could replacing the connectors with copper / thicker wires in 48v possibly increase bandwidth to cure this issue?

I am using the 32v supply it came with. I am using a Fosi Audio X4 phono preamp to feed my turntable signal to it. I set the gain on the preamp 3/4 full. Do you think this is enough gain, or should I run it wide open gain. I am powering 6ohm Sony Sscs5 speakers.

@JohnAudioTech

7 ай бұрын

If you can get the range of listening levels you want from the V3 volume control, then you are fine.

To drive my 4ohm speakers with 48V power adapters, does that mean I should use one with greater that 5 amps? Do you recommend a 48V, 10 amp power adapter?

@chinmeysway

Ай бұрын

that seems good but maybe not is that a thing commercially available ? maybe 36v 10a is safer and adequate

I wonder if you used a 48v 8amp commercial linear power supply , if that would be better and drive the v3 to max output 300w as listed on fosi litertuature?

@Douglas_Blake_579

Ай бұрын

Nope. Stay with SMPS ... their outputs are tightly regulated.

I have found that when I measure power output with digital amplifiers like this, I measure much more power before clipping with a sine wave than I do with actual music. That does not seem to be true with tube amps in class A or class AB, or a conventional, transistor amplifier. I think that this may be a reason why the advertised watt output for these amps exceeds what they actually sound like with music. I wonder if you would like to do a comparison test with actual music programming and see if you get the same result.

@Douglas_Blake_579

Ай бұрын

Sine wave, dynamic range == zero. Music, dynamic range == 10db or better. So you will obviously read far lower power on music than on a sine wave. No matter what class or type of amplifier.

Lol, not much difference with the 48-volt at 5 amps. It needs more current , like at least double the amps 😂 to even come close to rated 🤔and fosi audio plays safe for that TPA3255 which is capable of higher power output even at 4ohm load according to the data sheet . Good to see your back making videos.

@erickorozco3907

28 күн бұрын

Tengo el Fosi V3 y lo uso con una fuente de alimentación de 48V5A y funciona de maravilla. Y así lo recomienda Audio Science Review

What is the best power supply to use Fosi V3 with a pair of 6 ohms 130 W power speakers (aka Pioneer SP-FS52)? My other option would be to use a pair of Aiyima A07 Max in mono mode. Any thoughts?

@Douglas_Blake_579

Ай бұрын

I use a pair of the Pioneers in my main system, with an Aiyima A07 (original design) also TPA3255 based and a 36 volt 6 amp power supply. Measured power is about 80 watts per channel. The thing works like a charm ... it can easily raise 90 db spl in my listening area without any hint of distortion. Typically I will run the amp at 1/2 volume and use the media volume in my HTPC to adjust the actual listening levels... and that sits at about 40 to 60% most of the time, giving me 70 to 75 db spl listening levels. (Loud but not dangerous) I generally don't recommend more than 36 volts because the cooling solution in these tiny amplifiers is simply not up to the task and at 48 volts, they will overheat and go into protection if pushed.

@erickorozco3907

28 күн бұрын

@@Douglas_Blake_579 Tengo el Fosi V3 y lo uso con una fuente de alimentación de 48V5A y funciona de maravilla. Y así lo recomienda Audio Science Review

If We make our own variable power supply using buck converter or buck boost converter modules & power them using transformer or smps, will the output be noise free for powering audio amplifier circuits?

@johncoops6897

9 ай бұрын

Not really, there always will be ripple and noise to some degree. It takes very careful design and special filtering to ensure a noise free SMPS. For audio work it's usually better to have an unregulated supply and a large amount of capacitors, as that gives more headroom for audio peaks. A switch-mode supply will simply clip, whilst an unregulated supply (of the same rated power) will often give additional power for transients.

@amitghosh6966

9 ай бұрын

@@johncoops6897 Are those readymade variable Bench power supplies use Linear or switch mode Technology that you use to review amplifier circuits?

@johncoops6897

9 ай бұрын

@@amitghosh6966 - I am just a viewer like yourself. Both switchmode and linear supplies are used in various reviews, however lab supplies are generally designed for "fixed" (regulated) voltage and/or current, and they cost a lot more than a simple transformer-based audio power unit.

@amitghosh6966

9 ай бұрын

@@johncoops6897 What about the Siglent brand dual rail variable bench suppy? Is it switch mode type or linear one?

@johncoops6897

9 ай бұрын

@@amitghosh6966 - I don't know, but a quick search online will give you the answer. Of course you need to be a lot more specific than just knowing the brand... they probably sell both.

I didn't understand the calculation .50vrms in and 10.41 vrms out finally getting 26.37db. what's the formula for calculations?

@JohnAudioTech

6 ай бұрын

20Log(Vout/Vin)

@mohimadvani6425

6 ай бұрын

@@JohnAudioTech thanks 😊.

Does 110v or 240v make any difference on that power supply?

@Douglas_Blake_579

Ай бұрын

If it does, the power supply is faulty.

My friend, I want to make an amplifier that works with a phase splitter, but there is a power imbalance in the signals at the collector and emitter outputs of the single transistor (2N3904) phase splitter I made. I want clean signals with the same amplitude and opposite phase. I request from you: Could you please make a phase splitter and run it on your channel?.. You know very well that theory and real applications are different. That's why I need your information, thank you.

@Douglas_Blake_579

7 ай бұрын

If you want equal outputs the collector and emitter resistor have to be the same value.

Was 48 volt 5 amp or 10 amp?

OK...at what distortion level? S/N level? IM distortion level?

Dual monoblock s on 49 volts @ 11 amps Sweet @ hi pass 70 hz. 8ohm,8 in, 3 way. Duo 18 plate amp subwoofer. Illegally loud.

Redoing is a hard job,renovation home&technology room

Class ab video make

@johncoops6897

9 ай бұрын

Yes, he has many. You should check his videos before commenting.

These things come alive if you use a 42v lithium battery

Nah these amps can even run 2ohms. I run 4ohms for transducers without issues too

munies laundering 😆

Replace those mysterious Chinese green electrolytics with a reputable brand.

I bought a Fosi BR30D Pro... What a piece of junk. But, then again you get what you pay for. After about six weeks the subwoofer would just stop working. Power off then back on sub would come back for a short time. Now when you turn it on with the sub connected it sounds like it is going to destroy the sub. If you are thinking of buying ChiFi gear stay away from this brand.