• WANTED: Happy members who like to discuss audio and other topics related to our interest. Desire to learn and share knowledge of science required as is 20 years of participation in forums (not all true). Come here to have fun, be ready to be teased and not take online life too seriously. We now measure and review equipment for free! Click here for details.

Inexpensive mini-amplifiers: Discussion of power ratings and distortion

Xulonn

Senior Member
Patreon Donor
Joined
Jun 27, 2018
Messages
451
Likes
987
Location
Boquete, Chiriqui, Panama
#1
I am attempting to start this (hopefully) civil discussion in a non-confrontational manner, because I want to take a practical approach to evaluating internet-marketed mini-amplifiers, and not encourage rants or put-downs of purveyors of cheap audio gear and their products - although many of them deserve such a reaction. It is nearly impossible to find "honest" power ratings for many of the new breed of chip-amps compared to offerings from more "traditional" high-end and so-called "mid-fi" audio manufacturers. Respected mainstream and audiophile high-end niche manufacturers have historically been pretty good about publishing the details of the output of their products, but many "cheap" amplifier manufacturers have published misleading ratings for many decades. The current deluge of cheap Chinese-made amps continues that tradition of deception. What is marketed as an 80w amplifier by many vendors in that sector is most often not even in the same league as an 80w amplifier from a respectable amplifier manufacturer.

This is the $200 (Amazon price) Topping TP60 "80wpc" amplifier (11.95lbs shipping weight)...
Topping TP60.JPG Topping TP60 2.JPG
... which has an internal linear power supply with two toroidal transformers. One of these amps is on its way to Amir and I assume will be thoroughly tested. On the surface, it appears as though it might be one of the better options in the mini-amp field. Amir's testing should confirm or disconfirm that entirely subjective opinion.

And the $105 Topping PA3 "80w" amp (2.73 lb shipping weight)...
Topping PA3.JPG

...is on the way to me in Panama. The PA3 normally sells for $105 on Amazon, but I was able to buy one for $84 on a "one-day special" discount. Like the TP60, the PA3 also has an 80w rating, but uses an external "brick" style switching power supply. As you will see from the below response I got from Topping, the design is apparently is not as "robust" as that of the TP60. It seems that at 4Ω, the PA3 will overheat and cannot operate continously at 1% or less THD & noise, the generally accepted minimum distortion level to qualify as a "high fidelity" amplifier.

Topping appears to be one of the best manufacturers of inexpensive DACs based on Amir's testing and reporting on the Topping D10, D30 and D50 and their DAC/headphone amps. In their amplifier marketing, however, I assume that Topping needs to play the "watts game," because that is a necessity to survive in a market segment with a large percentage of unsophisticated mass-market customers/consumers. I just wanted to find out a bit more detail about the "proper" power ratings, which are seldom if ever, published in the advertising of this market segment. The fact that Topping even responded, considering that the answer contains a big negative, is surprising and much appreciated.

So it appears that currently, Topping is not ahead of the pack with mini-Class-D amp like they are with their DACs. But who knows - they might respond to criticism and "do the right thing." I do not regret my decision to buy a PA3, and will place it in my system and play with it when it gets here - probably in one week, and report on my experiences. Although I expect the PA3 to drive my 8Ω Paradigm Atom monitors adequately in my small, low-ceiling living/kitchen room, I will still probably upgrade to a Hypex Ncore amp eventually - if and when I can afford it. I would then keep the Topping PA3 for desktop use and backup duty.

Below is the email exchange that prompted me to start this thread, and I did tell Topping that I would discuss their response here at ASR. But I didn't wait to buy the PA3 as indicated in my email message because of the one day sale I stumbled upon at Amazon.

---------------------------------------------------------

On 7/18/2018 13:09,David Van Harn wrote to Topping:
Topping has an excellent reputation, and your DACs have tested very well at AudioScienceReview.com. Your products are described as being very well made with high quality components and hardware. However, "Maximum power at 10% distortion" is not a very useful specification for amplifiers, and does not allow a fair comparison with traditional audio amplifiers from established manufacturers.​
I am an audio enthusiast with over 50 years experience, and I would like to know the RMS power ratings for continuous output at 1% or less harmonic distortion for the PA3 and TP60 amplifiers. Then I will decide if I want to buy one of those products and a Topping D50 DAC via Amazon and have it shipped to me in Panama, where I live as a retired American expatriate.​
I will discuss your response at the AudioScienceReview.com forums, and I hope that you can provide me with honest and accurate information. Soon, the owner of that website will be testing the TP60 amplifier that he has recently ordered. This is an opportunity for you to confirm your company's reputation for clear and honest communication about specifications.​
David van Harn
Boquete, Chiriqui, Panama

-------------------
Response from Topping:

Dear David

Here's test results. We use resistance as load and test.

PA3(8ohm):
L: 56.51W(RMS), THD+N 0.99%
R: 56.58W(RMS), THD+N 1.01%

PA3(4ohm):
NA, because PA3 overheat before THD+N reach 1%

TP60(8ohm):
L: 68.30W(RMS), THD+N 1.01%
R: 68.70W(RMS), THD+N 1.06%

TP60(4ohm):
L: 54.54W(RMS), THD+N 1.02%
R: 55.08W(RMS), THD+N 1.05%

Due to individual differences, another product should be different from my test, but it will not be much different.

Best Regards!

Hailin Huang
TOPPING sales manager
26th Jiaomen Road
Huangge Town, Nansha, Guangzhou, China
Zip code: 511455
 

amirm

Founder/Admin
Staff Member
CFO (Chief Fun Officer)
Joined
Feb 13, 2016
Messages
20,566
Likes
25,244
Location
Seattle Area
#2
That is pretty good information you got from them. Interesting that the power output at 4 ohm is lower than 8 ohm though! There must be some kind of current limiting going on.
 

tomelex

Addicted to Fun and Learning
Patreon Donor
Joined
Feb 29, 2016
Messages
759
Likes
276
Location
So called Midwest, USA
#3
I look forward also to Amirs test at 100 milliwatts or whatever low output he standardized on, that's where we really find out how well the amp really is as well.
 

restorer-john

Major Contributor
Joined
Mar 1, 2018
Messages
2,354
Likes
3,737
Location
Gold Coast, Queensland, Australia
#4
There must be some kind of current limiting going on
The rails will simply be sagging under almost double the current draw based on those 4ohm numbers. By the interior shot, there are only two rail caps, so the unit is likely running the two transformers in parallel or one per rail- not one per channel.

Also, confirm with Topping those figures are both channels driven, from 20-20Khz, not just a single channel at 1KHz...
 

restorer-john

Major Contributor
Joined
Mar 1, 2018
Messages
2,354
Likes
3,737
Location
Gold Coast, Queensland, Australia
#5
I look forward also to Amirs test at 100 milliwatts or whatever low output he standardized on
The old standard for FTC ratings was pretty much this:

"with 8 ohm loads, both channels driven from 20Hz to 20KHz XXX watts per channel minimum RMS power with no more than 0.xxx% total harmonic distortion from 250mW to rated output"

Same for 4 ohm loads.

100mW is too low. Residual noise will always dominate and give erroneous results IMO.

This was with the caveat of a pre-conditioning rule of 1/3 power for 1 hour into 8 ohms- both channels driven. Note, the pre-conditioning rule and other parts have been watered down for multichannel AVRs.

Personally, I believe 1 watt is a decent number. It's where a lot of our listening is done and it's a nice arbitrary number that has been used for FR plots for 60+ years. Same for low level square wave testing and impulse testing.
 

Krunok

Major Contributor
Joined
Mar 25, 2018
Messages
3,844
Likes
1,977
Location
Zg, Cro
#6
That is pretty good information you got from them. Interesting that the power output at 4 ohm is lower than 8 ohm though! There must be some kind of current limiting going on.
My guess is that probably overheat protection circuit jumps in limiting the current.
 

Timbo2

Senior Member
Joined
Feb 27, 2018
Messages
312
Likes
168
Location
USA
#8
Parts Express on TP60

Specifications: • Power output: 2 x 80W (into 4Ω @ 10% THD), 2 x 48W (into 4Ω @ 0.1% THD), 2 x 50W (into 8Ω @ 10% THD), 2 x 27W (into 8Ω @ 0.1% THD) • Dynamic range: 102 dB • Signal-to-noise ratio: 98 dB • Power efficiency: 81% @ 80W into 4Ω, 88% @ 50W into 8Ω • Input sensitivity: 200 mV • Input voltage: 110 VAC, 60 Hz • Weight: 11 lbs. • Dimensions: 11.375" (288.9 mm) L x 6.625" (168.28 mm) W x 3.375" (85.73 mm) H.
 

Xulonn

Senior Member
Patreon Donor
Joined
Jun 27, 2018
Messages
451
Likes
987
Location
Boquete, Chiriqui, Panama
#9
Topping publishes a bit more information for the TP-60, which is based on the old Tripath TA2022 "Class-T" chip. The PA3 has similar "marketing ratings" but uses an external brick power supply, which I think is witching, not linear. Those two amps represent different approaches to moderately priced chip-amps based on their power supplies, with the more traditional TP60 being quite a bit larger, and about three times heavier because of its dual internal toroidal power supply transformers. Both amps certainly have more power than the original $30 ($40 list) Tripath-based Sonic Impact amplifier, and the TA2024 chip was rated at 6 [email protected]Ω.

I am confident that the PA3 will be a good match for my little system in my casita - my small rental house with a single main room - a tiny living room / kitchen, plus a couple of bedrooms. Rated at [email protected]Ω with a 19v power supply (but more likely 15wpc), the SMSL Q5 Pro DAC/Amp that I am using temporarily is o.k. However, with a built-in DAC, remote control, sub out and 7 EQ modes, is more complex than I like. But since I live in a remote region, I like to have a backup, and the SMSL will be perfect for that purpose.

I like having separate components that are as simple as possible with no features or controls that I will never use. I plan to use the SMSL Q5 as a DAC when the Topping PA3 arrives, but I buy a Topping D50 DAC via the next MassDrop to drive the PA3 amplifier.
 

trl

Addicted to Fun and Learning
King of Mods
Joined
Feb 28, 2018
Messages
669
Likes
432
Location
Iasi, RO
#10
That is pretty good information you got from them. Interesting that the power output at 4 ohm is lower than 8 ohm though! There must be some kind of current limiting going on.
From my understanding, the initial request was to measure the power on outputs until THD gets to 1%, this is why PA3 was not even tested for 4 Ohms ("NA, because PA3 overheat before THD+N reach 1%") and the TP60 has a THD of about 10% when gets to 80W @ 4Ohms.

However, quite a potent amplifier there, for such a decent price. It would be interesting to see some close-ups with the PCB and components inside, but also how square-waves look like. Also, SNR, dynamics etc. will be interesting too, of course.
 

trl

Addicted to Fun and Learning
King of Mods
Joined
Feb 28, 2018
Messages
669
Likes
432
Location
Iasi, RO
#11
A very good measurement setup of similar Class-D chips here: https://quantasylum.com/blogs/news/first-look-evaluating-class-d-power-amps-with-the-qa401 or here: https://quantasylum.com/blogs/news/quick-look-a-no-name-tpa3255-design

Also, some discussions here: https://www.audiocircle.com/index.php?topic=152869.0

Seems that with a good design and good PCB this amplifier can actually deliver very good amount of power with low distortions and very low noise. Given the Class-D efficiency, I understand why so many manufacturers are including Class-D amplifiers into their amplified subwoofers (even SVS does).
 

Sal1950

Major Contributor
The Chicago Crusher
Joined
Mar 1, 2016
Messages
5,725
Likes
3,212
Location
Central Fl
#12
t is nearly impossible to find "honest" power ratings for many of the new breed of chip-amps compared to offerings from more "traditional" high-end and so-called "mid-fi" audio manufacturers. Respected mainstream and audiophile high-end niche manufacturers have historically been pretty good about publishing the details of the output of their products, but many "cheap" amplifier manufacturers have published misleading ratings for many decades.
Not sure I would agree with that too strongly. Since the beginning of time manufacturers have been playing fast and loose with amplifier power ratings and measurements. The current Slick Willie approach to multich receiver ratings is yet another excellent example of finding ways to overstate a power rating..
https://www.audioholics.com/audio-amplifier/product-managing-receiver-platforms-power-ratings
https://www.audioholics.com/audio-amplifier/power-manipulation-in-av-receivers
 
Last edited:

Xulonn

Senior Member
Patreon Donor
Joined
Jun 27, 2018
Messages
451
Likes
987
Location
Boquete, Chiriqui, Panama
#13
Since the beginning of time manufacturers have been playing fast and loose with amplifier power ratings and measurements.
Thank you very much for your spot-on reply, Sal. That two year-old video is exactly what I was looking for in trying to better understand what an honest and accurate amplifier power rating looks like. I also better understand now - after all of these years - why a robust PS is so important.

One personal choice for me in audio is to utilize separate components. Now that I have retired to a "developing" nation (Panama) in the tropics where voltage surges and sags, power outages and lightning are common, electronic equipment can easily be damaged. I lost the Teac after a nearby lightning strike that hit a utility pole ~100 meters away right in front of my eyes - in spite of having a $200 Tripplite surge protector/UPS/AVR unit in use.

After losing the Teac a-H01, an Ice-Power DAC/Amp, I bought an SMSL Q5-Pro DAC/Amp/EQ with lots of features, for use as a temporary replacement and future backup unit. I an retired and living on a limited income, but over a few months managed to finally purchase the above mentioned Topping PA3 amp. When I got it, I didn't have a DAC, so I used the front audio/headphone output on my Intel NUC/Kodi HTPC, and the sound was terrible. When I finally received my new DAC last week - the SMSL Sanskrit 6th - I switched to the Toslink optical S/PDIF on the NUC to feed the new DAC, with a pair of old Audioquest RCA interconnects connecting it to the Topping PA3, and good sound quality returned. I haven't done any "critical listening" tests yet, I just enjoyed my digital format music and movies.

I now own four chip-based mini-amps:

Trends Audio 10.1 - $150 (Tripath TA2024 - [email protected]Ω for 0.1THD w/12v PS- probably the best implementation ever of the TA2024 which was made famous by the original Sonic Impact T-Amp) I bought this keeper about 10 years ago - and it is still going strong in my "portable audio system" powered by a 12v SLA battery, and fed by my Cayin DAP at our weekly artisan food, arts and crafts market where I sell my artisan woodturnings.

Lepai LP-2020A+ $27 (Tripath TA2020 - rated at [email protected]Ω, tests at 9wpc for 1.0%THD w/ 12v PS) I keep it as an emergency backup for the Trends amp.

SMSL Q5-Pro - $140 (Texas Instruments TAS-5342 - [email protected]Ω w/24v PS) This is now my backup for the SMSL/Topping DAC/Amp pair.

Topping PA3 - $105 (ST Microelectronics TDA7498E - [email protected]Ω, 1% Distortion w/ 32v PS) Paired with the Intel NUC HTPC, Synology NAS, SMSL Sanskrit 6th DAC and a pair of Paradigm Atom v6 monitors, and Samsung 40" TV, it is part of the main system in the little three-room house that I rent.

Maybe I'll save up and get a USB/PC oscilloscope kit just to compare these four amps! (And then again, maybe I won't.) :cool:
 

trl

Addicted to Fun and Learning
King of Mods
Joined
Feb 28, 2018
Messages
669
Likes
432
Location
Iasi, RO
#14
You could also use RMAA with a good soundcard (ADC), but also sine-waves and square-waves from audiocheck.net.

However, I’ve seen cheap scopes on Banggood & Alibaba, unless you want to go “higher”.
 

BillG

Addicted to Fun and Learning
Joined
Sep 12, 2018
Messages
816
Likes
734
Location
Auckland, New Zealand
#15
I've been using a Texas Instruments chip based integrated amplifier for several months now and am quite impressed with it. While it's not particularly beautiful, and its operating system is basic, it does a more than adequate job for a PC and streaming based bedroom system I built recently to drive some Infinity Reference 152 speakers.

http://averagejoeaudiophile.blogspot.com/2015/12/infinity-reference-r152-infinitys-high.html

Here's the device:

https://www.aliexpress.com/item/I-A...-150W-2-CM6631A-24Bit-192KHz/32594479261.html

I'm driving it with a low noise 32v 5a switching power supply.

Here are some of distortion and frequency response measurements an associate from another forum ran on it:

v200d.png v200r.png

Kind regards...
 
Last edited:
Joined
Sep 27, 2018
Messages
12
Likes
3
#16
I just registered here so that I could join this conversation. Like many I enjoy nice sound but don't have the time, expertise, or money to think about going down the full audiophile path.

A couple of years ago I decided to put a basic system into our garage, and needed it to be powerful enough for accompanying a small spin class that we host with local cyclist friends. After some basic research, I ended up with a set of the Pioneer BS22 bookshelf speakers and the SMSL SA-98E amp. I'm typically running the amp directly off of my phone using spotify, and more recently have added a chromecast audio to it that makes it even more convenient. For a garage setup, I think it sounds excellent. I've been extremely happy with the setup for it's use, but have always felt that the SMSL amp was a bit of a liability, as it pushes the speakers to a painful volume at about the halfway mark. Others usually lead the spin class and thus control the amp/volume, and I've worried that a thoughtless bump could blow out my speakers. With this in mind, I decided to try a slightly lower powered amp and recently bought the Topping PA3 as discussed above. The two amps are similar in size (actually the SMSL is slightly smaller) and to my understanding use the same TDA7498e chip. For this reason I expected them to sound reasonably similar despite the significant difference in claimed power.

I've had only limited time to compare the two, not enough time to truly compare quality of sound, but if the gain setting at similar volume levels is any indication, the relative wattage output seems to be about right, with the Topping requiring about double the volume setting for the same speaker volume. I should have expected this, but I now realize that I'll occasionally be running the amp at 90% or above on the volume dial, and have wondered if this is simply not the right tool for the job in that size of room with those particular speakers. If the amp is generating significant THD at this volume level, other than slightly degraded sound, are there any risks to my speakers? My guess is that more sensitive speakers would be better suited, but I don't see comparably priced and performing speakers as the BS22's that offer higher sensitivity, so I may be stuck either running the amp often near max volume or sending it back and buying another SMSL SA98e.

I want to keep the Topping if I can, if for no other reason that I always prefer not to return things I've chosen to buy. Also, I like the power/input button (no LED while powered off, gives the impression that it might actually be turning the amp off, rather than simply going into standby) and the slightly higher friction volume dial. The SMSL knob rotates too easily in my opinion, and makes me nervous because I don't want to damage the speakers.

Very early impressions also give me the impression that the SMSL might sound better to me, but part of that might be that I didn't have the gain calibrated to the same level during my initial comparison. I'll try to spend some more time with it and will plan to share my thoughts here.

-Jeremy
 
Last edited:

amirm

Founder/Admin
Staff Member
CFO (Chief Fun Officer)
Joined
Feb 13, 2016
Messages
20,566
Likes
25,244
Location
Seattle Area
#17
If the amp is generating significant THD at this volume level, other than slightly degraded sound, are there any risks to my speakers?
There can be but you would hear the distortion readily in that case. If the sound is not getting distorted or shrill, then you are OK running it that way.

I will be measuring it soon and we will get more insight into what it is doing at those volume levels.
 

Arnandsway

Active Member
Joined
Sep 13, 2018
Messages
205
Likes
144
#19
I would like to add the SMSL AD18 into the mix. Being an fully digital 80W amplifier, that retails for €129.
 
Top Bottom