Topping PA7 Plus Amplifier Review

[Elitzur–Vaidman]

Not sure that means the same thing as this:

How To Set Up An Amplifier [Bridge vs Parallel vs Stereo]​

It's my understanding that it's effectively the same thing. Not all amplifiers are bridgeable.

 

[digicidal]

It would be nice if Nord would allow both RCA and XLR on the same entry level model...

While the average ASR member might be likely to swap preamps mulitple times over the life of their power amp... I'm not sure the average consumer is. Even within our ranks the odds of moving from a pre with RCA only to one with XLR only is fairly unlikely. At least they offer configurations with both options (and even more valuable IMO an optional 12V trigger).

I just picked up the Monoprice M8125 since it's on sale for a great price right now, and there's not even an option to have one with RCA inputs... but it does include switched trigger/auto functions. It's a bit cheaper than the Nord option (per channel)... but due to PS limitations is not capable of hitting the full output of all 4 NC252 modules simultaneously. It's also uglier than the Nord options IMO... but I don't care about that anyway.

There's almost never that magic bullet that combines features, power, style... certainly at these price points.

 

[delta76]

Can this amplifier be safely used bridged if I want even more power for a single speaker?

it was not in their specs, so it is very likely not designed that way - so no bridge for you

 

[raest]

This is the same logic that lead to opamp rolling in headphone amps a couple of decades ago. What matters is the implementation more than the chip.

Topping was able to create a 102 dB SINAD amp while the A07 is 82 dB SINAD. Topping is 191 watts at 4 ohm load vs. 77 for the A07.

This PA7 Plus is able to perform more like a Hypex nc252mp amp despite using a TPA chipamp for its class D output stage. If it performs more like a $500 hypex then a $75 basic TPA implementation dont be surprised if the prices match.

i would look at it this way: the relatively new and modern Hypex is used in a wide variety of implementations, all within spec, nothing fancy or exotic really to "squeeze" out every db of pointless [as in, it's already more than transparent enough for 99,999% use cases] SINAD for the ridiculous chasers, so it's never really strained in there... all while being produced by a company with a proven track record of reliability etc

on the other hand, you have a company with dubious reliability in those implementations of a 7 year old design, even more dubious concern for the customers, trying to eek out every last db of that pointless SINAD, using every trick they know so it gets higher on Amir's list, so that unaware customers get tricked (like i did) or the aforementioned "chasers" can get their graph fix, making me seriously question, again, the long term reliability of such a constellation of conditions.

to try and make a car analogy, which would you trust more, a sports car made by Lexus with a new V8 of theirs with 400hp tested at their end, or a Volvo with a Renault V6 only ever used in applications with a max of 300hp until this point, being tuned to produce over 450hp in said Volvo?

i would surely admire the engineering and ingenuity in the latter, but as a consumer, i'd never even consider it, let alone buy it. and as these reviews on ASR and similar sites are geared towards consumer recommendations rather than in-depth geeky analyses of said products...

fool me once...

 

[EJ3]

It’s big difference to the mentioned spec:
Output Levels

2 V RMS for rated specifications.

It meets AND EXCEEDS spec, doesn't it?

 

[linuxfan]

Can this amplifier be safely used bridged if I want even more power for a single speaker?

This subject has been covered before. The question of whether a stereo amplifier can be bridged to mono has both a technical answer, and a practical answer.
The Topping PA5/PA7/PA7-Plus are based on TPA325x chips. In stereo mode these chips are already configured as bridge-tied load, and for mono they can be configured in parallelled BTL (PBTL).

So for a single-chip amplifier such as the PA5, yes, it's technically feasible to change its factory mode of BTL to PBTL to change it from a stereo amplifier to a mono amplifier ... but from a practical standpoint, Topping gives no provision to change the amplifier from one mode to the other.
For a dual-chip amplifier such as the PA7 and PA7Plus, both chips will already be in PBTL mode, so there's no way to make these amplifiers mono, neither technically nor practically. But Topping is already giving you dual-mono regime, within a single box ... so what is it that you want - more power? With the PA7 & PA7Plus the TPA325x chips are already at their highest-power configuration.

Or do you simply want a (high power) single mono amplifier? If so, the Sabaj A20a (2022 version) is probably your best option -
http://www.sabaj.com.cn/en/productshow.asp?id=92

 

[JktHifi]

It meets AND EXCEEDS spec, doesn't it?

but very far difference from the spec. It’s measured as 9 Vrms

 

[charlielaub]

I apologize for expecting utility and fidelity, rather than pointless measurebation

As I wrote in the post you quoted, the volume defeat switch on the back (which wasn't called out in the review, and one has to squint to see in the picture) upgrades the volume knob from demerit to useless appendage.

As a basic amp, this one, assuming reliability etc., seems fine enough so long as one's OK with a small and load-invariant but broad treble dip. Since most electronics are so irrelevant in terms of effect on the actual sound of a music reproduction chain, it's hard to care too much one way or the other..

I'm not interested enough to actually the test the audibility of that treble dip (not in the market for a basic amplifier, and honestly if I were I would prioritize flat FR anyway), but it would be eye-opening if a small but wide bandwidth treble depression like that is in fact inaudible. One can imagine a certain loonie-with-a-vendetta lining people up to do a double blind test to smear @amirm and "prove" two Amir-recommended amps "sound different" without giving appropriate context around either the reason for the difference or the practical impact of it.

JFC dude, don't be such a troll. Everything you say is laced with negativity. For example:

• "pointless measurebation"
• "upgrades the volume knob from demerit to useless appendage."
• "certain loonie-with-a-vendetta lining people"

How about instead saying:

• "defeating the volume control wouldn't be useful FOR ME"
• "I THINK THAT the rolled off upper octave might/might-not be problematic"

If this forum becomes littered with this sort of trash talk why bother to visit here?

 

[ernestcarl]

it was not in their specs, so it is very likely not designed that way - so no bridge for you

Yeah, no worries. I might just go for one of the Buckeye amps instead.

 

[linuxfan]

it was not in their specs, so it is very likely not designed that way - so no bridge for you

Details in post #286

 

[ernestcarl]

Details in post #286

I'm new to the world of external amplification as all my speakers have been internally powered...

Suppose I wanted to provide power to this PA speaker up to its rated 112dB continuous spec: https://www.fulcrum-acoustic.com/product/rx699-6-coaxial-loudspeaker/

Would something like the ff. be way overkill?

Buckeye Amps

Buckeye Amps utilizes the most advanced audio amplifier technologies available. Authorized seller for Hypex and Purifi Class D amplifiers. Based in the US. Free shipping and worldwide service!

www.buckeyeamp.com

Or, maybe not by very much...

 

[linuxfan]

That speaker appears to be for public address applications, and it's specified as 16ohm. So I would be aiming for a public address amplifier, rather than a hifi amplifier.
I suggest you email Fulcrum Acoustic for their advice - give them full details about your intended use of the speaker/amp.

 

[NTK]

I'm new to the world of external amplification as all my speakers have been internally powered...

Suppose I wanted to provide power to this PA speaker up to its rated 112dB continuous spec: https://www.fulcrum-acoustic.com/product/rx699-6-coaxial-loudspeaker/

Would something like the ff. be way overkill?

Buckeye Amps

Buckeye Amps utilizes the most advanced audio amplifier technologies available. Authorized seller for Hypex and Purifi Class D amplifiers. Based in the US. Free shipping and worldwide service!

www.buckeyeamp.com

Or, maybe not by very much...

If you want to drive this speaker to its max rated power handling capacity, you'll need an amp that can provide 53 V output, which means the amp needs to have an 8 ohm power output rating of 53^2/8 = 351 W. The Hypex NCx500 is rated to 380 W @ 8 ohm, which just makes it.

 

[375HP2482]

Anyone guess what they did to get this performance? I would guess that internally there is a TPA per channel to make this fully balanced internally and after the output filter they are using the final signal to feed an opamp to form a composite amp and get the load invariance, high gain and high SINAD.

It's all about feedback implementation -- more complex, sophisticated feedback compensation schemes allowing higher open-loop gain at audio frequencies yet with adequate closed-loop phase margin for stability. Texas Instruments shows how PFFB alone can improve SINAD 4-6 dB over its stock 325x Eval Board. For the rest one can look to Mr. Putzeys' analyses and/or advanced studies in control systems analysis.

During earlier years when solid-state amplifiers were relatively young, somebody (likely tube-o-philes) appropriated the term TIM (Transient Intermodulation Distortion) from communications theory. This was likely meant to showcase the wider bandwidth and better open-loop linearity that tube amplifiers exhibit relative to their SS brothers -- which is now being revived to critique the lower bandwidth of Class-D amplifiers like these versus mature SS designs.

They concluded that the ringing observed from, say, a squarewave or tone-burst stimulus is an expression of deleteriously-excessive feedback, which is a somewhat misguided interpretation of what is widely regarded as phase margin/stability. The term "TIM" is simply another descriptor for a bandwidth-limited system (known to earlier generations as the Gibbs phenomenon). While it is true that many Class-D amplifiers express significant ringing near the output filter's resonant frequency (especially under no-load conditions), it is still within the margins of stability and, crucially, outside the audio passband.

Whenever something new and significantly different appears there is usually reaction, often negative (or, if you are RCA's David Sarnoff, lawsuits.) It happened with FM radio, CDs, mp3s, and Class-D power amplifiers which have now matured enough to displace the earlier, less-efficient ways.

 

[ernestcarl]

That speaker appears to be for public address applications, and it's specified as 16ohm. So I would be aiming for a public address amplifier, rather than a hifi amplifier.
I suggest you email Fulcrum Acoustic for their advice - give them full details about your intended use of the speaker/amp.

I might just do that as well. The speaker distance would be anywhere between 1 to well over 4 meters -- application will vary for indoors and outdoors as I'm treating this now more as an "experiment" of sorts.

 

[voodooless]

I'm new to the world of external amplification as all my speakers have been internally powered...

Suppose I wanted to provide power to this PA speaker up to its rated 112dB continuous spec: https://www.fulcrum-acoustic.com/product/rx699-6-coaxial-loudspeaker/

You’ll need about 160W to do that.

Would something like the ff. be way overkill?

Buckeye Amps

Buckeye Amps utilizes the most advanced audio amplifier technologies available. Authorized seller for Hypex and Purifi Class D amplifiers. Based in the US. Free shipping and worldwide service!

www.buckeyeamp.com

Or, maybe not by very much...

The main issue is that the speaker is 16 Ohm. That doesn’t leave modern amps with a lot of power because they are optimized for low impedance operation.

 

[ernestcarl]

You’ll need about 160W to do that.

The main issue is that the speaker is 16 Ohm. That doesn’t leave modern amps with a lot of power because they are optimized for low impedance operation.

I have been looking at some PA amps as well, but just about all of them have internal fans or have more channels than I care for...

 

[Elitzur–Vaidman]

You’ll need about 160W to do that.

The main issue is that the speaker is 16 Ohm. That doesn’t leave modern amps with a lot of power because they are optimized for low impedance operation.

Shouldn't any amp that can do 320W @ 8Ohm be fine?

 

[voodooless]

Shouldn't any amp that can do 320W @ 8Ohm be fine?

Possibly.. you need at least a 51V power supply to get 160W into 16R.

 

[Sokel]

I have been looking at some PA amps as well, but just about all of them have internal fans or have more channels than I care for...

Why not have a look at icePower 1200as2 based one?
After all the company's description is this:

Order the SoundImpress ICE1200-2CH Stereo Amplifier | Powered by ICEpower

Buy the ICE1200-2CH online at SoundImports ✓ Same day shipping ✓ Low shipping rates

www.soundimports.eu

AS1200 ICEPOWER Based CLASS D Amplifier | Apollon Audio Hypex Purifi Premium Amplifiers

apollonaudio.com

Nord Two ICE1200AS2 Stereo Power Amplifier - Nord Acoustics Ltd

The Nord Two using the brand new ICE Power 1200AS2 module incorporating the new highly advanced ASIC based ICE Edge Chipset technology. Not only does this bring a wide range of built in features but offers superb sound that gets close to our NC500 SE at an incredible price. In standard spec the...

nordacoustics.co.uk

I would e-mail them.