Topping PA5 measurements )

[Astojab]

I just shared a class A\B amp with multiple extra functions including DAC and phono stage for 400$ what are you talking about?

I am talking about this being a great solution for a DESKTOP setup, since at least I dont use anthing but my PC in that setup. I dont think the Denon you post is even remotely for the same target audience. That would be the more expensive PMA 50, which has a more comparable size and fits much easier on a pc desk .

 

[Vini darko]

Yeah definitely. No matter what speakers it can drive, as long as it can drive some speakers loud enough, this is a game changer. I guess this is more me trying to figure out what speakers i could buy to use with this.

Most bookshelf type speakers in nearfield will be fine. Only really inefficient ones may be an issue. And if you hand off bass duties to sub then even better.
With this amp you get 5W per channle with 10x power for dynamic peaks. Not that many speakers that won't be into hearing damage levels at that point nearfield.

 

[abdo123]

Linearity by definition requires that addition and scaling are consistent,

Sure that's a perfectly plausible way to describe the definition.

level up or down will produce consistent results and always land on the curve.

yes it will land on the curve since the curve is a function of level and IMD% not sure how that's helpful for the discusion.

However level up or down obviously does not provide consistent results (addition and scaling are not consistent, thus non-linear). for example the distortion DROPS when the level scales up (between -25dBFS and -20 dBFS) while the distortion rises when the level scales up between -5 dBFS and 0 dBFS.

[/spoiler]
Take the THD+N vs. frequency plot. THD+N will vary as a function of frequency. I'm pretty sure that in almost every case the system will be effectively always linear because whatever frequency you as it to reproduce, it will give you that level of THD+N. I think the only devices that will fail here are those that show random THD+N over frequency. I guess that could be due to leakage from some other internal circuit that varies the amount of interference over time. Maybe discussions about certain devices potentially demodulating AM signals into the audible range are relevant, but that's sort of an extraneous factor to what you're talking about.

What term would you use for THD% inconsistencies with regard to frequency?

Btw this phenomenon is way way more common than you think, infact outside of very well engineered Class A/B, Purifi Eigentakt, Benchmark ABH2, and some Class D GaN transistor impelementations, mainly Orchard Audio, (and well now the Topping PA5) I haven't seen a 'simple' Class D amplifier really tackle this well. Hypex NCore is good but not perfect.

 

[antcollinet]

Yeah definitely. No matter what speakers it can drive, as long as it can drive some speakers loud enough, this is a game changer. I guess this is more me trying to figure out what speakers i could buy to use with this.

Why is it a game changer? It is a relatively low power amp at a similar price to similarly powered amps but with fewer features. SINAD is good, but good to the extent that it is better than needed for most - or at least not significantly audibly better than the competition. I think it would need to be 1/2 the price or double the power to be a true game changer.

tl;dr - I don't understand the enthusiasm.

 

[pozz]

yes it will land on the curve since the curve is a function of level and IMD% not sure how that's helpful for the discusion.

The curve won't randomly fluctuate every time you measure it. It's stable.

I think the right way to put it is that the distortion is nonlinear with level when the slope of the curve changes. That's the sign of another mechanism interfering, like saturation or clipping at the end of a lot of graphs.

What term would you use for THD% inconsistencies with regard to frequency?

I would probably just say that. I don't know how to give it a single word descriptor. I'd even say it's not necessary. You can just use a phrase and likely be clearer. "Linear harmonic distortion" on the other hand is really hard to decipher.

Btw this phenomenon is way way more common than you think, infact outside of very well engineered Class A/B, Purifi Eigentakt, Benchmark ABH2, and some Class D GaN transistor impelementations, mainly Orchard Audio, (and well now the Topping PA5) I haven't seen a 'simple' Class D amplifier really tackle this well. Hypex NCore is good but not perfect.

You mean keep noise and distortion consistent as a function of frequency throughout the spectrum? Yeah, it's hard for any amplifier. They manage it just for a certain band. Bob Cordell's book spends a lot of time on that IIRC.

 

[pozz]

Why is it a game changer? It is a relatively low power amp at a similar price to similarly powered amps but with fewer features. SINAD is good, but good to the extent that it is better than needed for most - or at least not significantly audibly better than the competition. I think it would need to be 1/2 the price or double the power to be a true game changer.

tl;dr - I don't understand the enthusiasm.

I'll speak for myself. I like that Topping is able to consistently produce great results. Sure it's a limited purpose power amp, but the way most companies release products shows little innovation or even improvements with successive generations. I'd love to see a power amp with a lot of output and consistently low noise and distortion, like we see here, but I don't have much hope for traditional manufacturers to produce anything like that.

 

[abdo123]

is that the distortion is nonlinear with level when the slope of the curve changes.

Isn't that exactly the case with the ESS IMD hump though?

You're really confusing me.

 

[pozz]

Isn't that exactly the case with the ESS IMD hump though?

You're really confusing me.

Like I said, I don't have a great grasp of the vocab or the concepts. What I'm trying to do is put together your phrasing with your examples, and figure out where both of us are right/wrong.

I think where I'm wrong is lumping predictable behaviour with linearity. What I can't reconcile is how a change in slope, which is nonlinear, is nonetheless reversible for the IMD vs. level graph. Maybe it's because I don't understand enough of the underlying action of the device. Perhaps when you are in the region of the IMD hump, the spectral content as well as the level of those additional spurs changes. Regardless, if we go back to what you wrote before:

i think what's important is the linearity of the distortion not really it's amount in absolute terms.

So your idea is that if you have some sort of unexpected fluctuation in distortion vs. level, that's actually more impactful than the level of distortion as such. I think you're right in that it's probably indicative of good engineering, but likely wrong when you take the idea further and extrapolate in terms of audibility and overall impact.

 

[pma]

If we are sure that we operate an amplifier below clipping, then the only reliable indicator that it might sound "different" is a modulation of frequency response at amplifier output by complex impedance of the speaker connected, when it exceeds audible limits. Any other parameters like "SINAD" are unpredictable, uncorrelated and unreliable measures of possible sound difference, if kept below reasonable limit like 1% of THD+N and IMD.

 

[WolfX-700]

If this amp is truly $399--and I believe Wolf is normally correct with his info--then I personally will probably not be interested. I'd prefer to either sacrifice some performance and pay a lot less, or pay $100 more and get 3 times the power and performance that is good enough that I will not be able to hear the difference. However, that in no way changes the fact that this appears to be a remarkable achievement--an integrated amp with balanced inputs and state of the art noise and distortion numbers in a very compact package and enough power for most speakers in small rooms, in a very small footprint.

Actually, I only said less than 399usd I believe topping will maintain its reputation in C/P

 

[August]

Actually, I only said less than 399usd I believe topping will maintain its reputation in C/P

Chairman Wolf

 

[Klint]

Any info when it will be available?

 

[daniboun]

Any info when it will be available?

Would say, within a few weeks.
As per THD Figure, seems the PA5 is using a TPA3255 chip more than a MA5332MS chip.

In preview ... I share with you the very first photo of the TPA355 from Allo (Design in process)

ALLO TPA3255 (measures from manufacturer) :

THD+N 5W , 1Khz 0.00014
THD+N 100W 20-20Khz 0.0097
THD+N 10W 20-20Khz 0.0091
SNR : about 117DB

 

[pma]

Lot of screws (with wrong head) on top .

 

[daniboun]

Lots of screw sure...but gives an idea of the design. A few people asked me if it is going to be a balanced amplifier..now you know )

 

[Zek]

What ...

 

[pma]

Bedroom workshop?
If it is a functional sample only, then OK, but if the photo is used as a promotion - then it is horrible.

 

[antcollinet]

It’s described as design in process. It is a protypte - probably functional only.

 

[daniboun]

It’s described as design in process. It is a protypte - probably functional only.

Exactly. I shared the innovations inside a few pages before
In any case, I wonder what Allo has in store for us in the final version! And especially if the announced measures will be respected .... case to follow

 

[Michal]

They'll have to try hard because Topping and SMSL are just around the corner. PA5 is here, and what will happen next ;-)