Leveling up from my Wiim Ultra Amp

[harkpabst]

The Wiim Amp Ultra is much better than Vibelink in driving a difficult load.

But you need a LOT more power/current for it to make a strong, or even medium difference.

It's not quite clear why the (newer) WiiM Amp Ultra got the dual chip PBTL implementation, but the WiiM Vibelink Amp did not.

But the WiiM Amp Ultra is still limited by its PSU when it comes to driving very low impedances. It's stable into 2 Ω loads, but it cannot keep the output voltage constant.

 

[Ropeburn]

That's a popular MYTH. While IT'S TRUE that you can burn-out a speaker by pushing the amp into clipping, higher power is even MORE DANGEROUS.
Why Do Tweeters Blow When Amplifiers Distort?


Voltage, current, impedance and power are all mathematically related. (You can look-up the formulas if you're interested.) If your amplifier is putting-out 100W the only way to get more current is to increase the voltage which also increases current and power.

Or, lower impedance speakers will "pull" more current and power. Or if you put two 8-Ohm speakers in parallel you've got a 4-Ohm load. Assuming the amplifier can handle the 4-Ohm load, they'll both get the same voltage, current, and power so the total current and power are doubled.

Or with no speaker connected (infinite impedance or resistance) the voltage is still present but no current flows and no power is coming out.


You might need bigger woofers or a subwoofer. Size isn't everything but you aren't going to get "realistic bass" that you can feel in your body from a tiny woofer.

Adding to that, it's actually not that easy to tell whether on approaching full blast volume it's the amp or the speakers reaching their limits. Or both. The volumes at which that starts to happen are usually high enough that your ears are starting to compress and distort as well. And that of course is unmeasurable.

 

[Sokel]

That's a popular MYTH.

No, it's not.
If clipping was harmless, we would be also able to test amps (and I'm talking all amps) and speakers with square waves.

But we don't.

 

[john61ct]

It's stable into 2 Ω loads, but it cannot keep the output voltage constant.

Do many home audio speakers go that low?

My OG LS50s are nominal 8Ω but can apparently go "a bit under" 4Ω with lots of LF at high SPL.

So I look for amps that are stable to 2Ω just to have a comfort level.

I realize a 3e A7 mono fed 51V by a 600W Mean Well would add "a bit more" oomph at max-safe SPL testing

but all the value added by the WAU to me makes it worth a little SPL compromise and a bit more money, even if mostly used just as a power amp with safe output limiting, DSP for DRC/PEQ etc

 

[StephenMarkLay]

Do many home audio speakers go that low?

My OG LS50s are nominal 8Ω but can apparently go "a bit under" 4Ω with lots of LF at high SPL.

So I look for amps that are stable to 2Ω just to have a comfort level.

I realize a 3e A7 mono fed 51V by a 600W Mean Well would add "a bit more" oomph at max-safe SPL testing

but all the value added by the WAU to me makes it worth a little SPL compromise and a bit more money, even if mostly used just as a power amp with safe output limiting, DSP for DRC/PEQ etc

The wiim amp ultra does fine on both my OF Ls50 and Linton 85.

 

[gasolin75]

Don't get the difference between single and dual chipped tpa 3522 amps

The vibelink does have lots of power where a dual chip amp back in the day could play louder than the same amp with 1 chip

Hate the volume knob on my ultra streamer it's like something is touching the knob,scratching, when i try to use it, the vibelink is butter smooth

Most spEaker you would pair any wiim amp with, is no lower than 3.5 ohm mine is rated down to 4 ohm

 

[john61ct]

TPA3255 is a 4-channel chip, googling will reveal lots of explanations including TI docs on BTL mode vs PBTL and the different power output specs.

The other optimisation is PFFB, which A7 got right, not so clear on WAU's.

I think Vibelink was just earlier, we're all just learning as we go

 

[harkpabst]

Do many home audio speakers go that low?

My OG LS50s are nominal 8Ω but can apparently go "a bit under" 4Ω with lots of LF at high SPL.

So I look for amps that are stable to 2Ω just to have a comfort level.

No, most definitely don't. But supporting such low loads is the main benefit of the two chip PBTL design. It also lowers the output impedance, but this is mostly dominated by the analog output filter anyway. Better coils and PFFB will have a bigger impact than PBTL vs. BTL.

but all the value added by the WAU to me makes it worth a little SPL compromise and a bit more money, even if mostly used just as a power amp with safe output limiting, DSP for DRC/PEQ etc

I wasn't talking down the WiiM Amp Ultra in an y way. It's a fantastic all-in-one device and worth every penny. It's just that PBTL doesn't really make it a better power amplifier than the WiiM Vibelink Amp. SINAD is identical. Power output is almost the same (PBTL doesn't get you higher power output into 4 ohm or higher loads). The power vs. distortion curves are even better for the Vibelink Amp.

If all you need is a power amp (e.g. because your already have the WiiM Ultra) I see absolutely no reason to pick the WiiM Amp Ultra ove the WiiM Vibelink Amp. Unless your speakers actually dip below 2.7 Ω (but even then you might need an even more powerful amp). As a stand-alone device the WiiM Amp Ultra ist hard to beat.

The vibelink does have lots of power where a dual chip amp back in the day could play louder than the same amp with 1 chip

A single TPA3255 can play just as loud as a dual TPA3255 implementation with nominally 8 Ω or 4 Ω speakers. More power into the same impedance needs more voltage. PBTL doesn't offer more voltage over BTL, just potentially more current. But more current will only be needed into lower load impedances.

The same voltage into the same impedance always results in the same current (this is called Ohm's Law). A PBTL design can provide the necessary current into 3 Ω or lower loads, but only if the power supply is up to it. Otherwise, the same thing happens as with a similar BTL amp: The voltage will drop, so no power increase into lower loads.

The PBTL implementation might potentially provide a somewhat higher sustained power due to doubled surface area for the heat transfer from the chip.

Hate the volume knob on my ultra streamer it's like something is touching the knob,scratching, when i try to use it, the vibelink is butter smooth

They invented the remote control and the smartphone app for that. Totally different technology in these cases.

I think Vibelink was just earlier, we're all just learning as we go

I'm almost sure that the Vibelink Amp was originally intended as a PBTL design. As has been pointed out before, implementing PFFB is not that easy and it's even more tricky with PBTL. That's my explanation why the power amp didn't get PBTL, but the all-in-one integrated did. But the difference is really mostly negligible.