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Inexpensive mini-amplifiers: Discussion of power ratings and distortion

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#41
Yes it requires modifying the board, specifically removing and soldering surface mount resistors, which are really tiny. I've done it myself a couple of times. But yes, it's not fun to mess with stuff that small.
Following a phase of fascination with those "new" amps, I'm growing more and more disgusted by them, and the wild claims made about them by some resellers. A gain setting issue? That's unacceptable. The PA3 ain't exactly cheap either. For instance Yamaha amps start at about $150, new. You would never get an issue like this on a mainstream cheap amp.
 
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#42
To be honest on PA3 is not a particular problem. For me is just annoying as i usually stand very close to my speakers, but for others this is something irrelevant. Plus is different from amp to amp, i plugged my backup smsl sa-50 and it has a lower noise but the sounds is less dynamic and detailed.

Then if we want to pair with entry level AB amps you have to consider dimensions, weight, heat production and price. Most of these amps are pretty much cheaper and on the other hand there must be similarities in sound for a direct comparison
 

JJB70

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#43
There is no shortage of second hand very good stereo amplifiers with years of life left in them and which are in a different world from these things in terms of build quality. And you can buy entry level amplifiers from Yamaha, Onkyo, Marantz etc for not that much more and have a bit more confidence in after sales service.
 
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#44
To be honest on PA3 is not a particular problem. For me is just annoying as i usually stand very close to my speakers, but for others this is something irrelevant. Plus is different from amp to amp, i plugged my backup smsl sa-50 and it has a lower noise but the sounds is less dynamic and detailed.

Then if we want to pair with entry level AB amps you have to consider dimensions, weight, heat production and price. Most of these amps are pretty much cheaper and on the other hand there must be similarities in sound for a direct comparison
Maybe but mainstream manufacturers have started to get into switching amps and combo dac/amps. There's an Onkyo model that looks excellent around $550 with tons of features , Yamaha had a small class D unit for around $200 that's also available with a DAC. The new iteration is DAC /amp only. IMO if the mainstream manufacturers decide to get into that market they can do so at comparable prices or just slightly higher, and crush the competition, with the added benefits of no bad surprises due to iffy QC and/or engineering, and a full worldwide warranty. The comparatively low price should be no excuse. I have a dysfunctional FX AUDIO unit that's just been a waste of money, however little money, and I'm almost reluctant to sell it, knowing the buyer will get a bad sounding unit.
 
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#45
the market is definitely leaning towards units that can handle multimedial purposes without great dimensions and prices.

that's why i'm looking to replace my unit with something that feels more premium to complete my desktop setup. I have lots of cheap options: SMSL, FX-audio, DIY boards, etc. but i'll leave them as material for future experiments, or maybe as a backup unit.
 
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#46
Been looking for a good budget amp, I have a decent set of speakers I think in a pair of Monitor Audio Radius 45 bookshelf speakers (correct me if I'm wrong, I can invest in a new pair of speakers if there are better for not too much more) for nearfield listening at my desktop. Going to by a separate dac and amp, but not sure what amp to get. I got a cheap 50x2w amp that sounded WAYYY worse than my old lepai 15x2w amp so I went and refunded that. Scared to buy a crap amp again. I am a college student and don't have too much cash on hand, so I'd prefer something under $100. I dont care about stuff like tone control, etc, or even volume if the sound is going to be fine just being controlled from my pc or a DAC. What's the best amp under $100?
 
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#47
Maybe but mainstream manufacturers have started to get into switching amps and combo dac/amps. There's an Onkyo model that looks excellent around $550 with tons of features , Yamaha had a small class D unit for around $200 that's also available with a DAC. The new iteration is DAC /amp only. IMO if the mainstream manufacturers decide to get into that market they can do so at comparable prices or just slightly higher, and crush the competition, with the added benefits of no bad surprises due to iffy QC and/or engineering, and a full worldwide warranty. The comparatively low price should be no excuse. I have a dysfunctional FX AUDIO unit that's just been a waste of money, however little money, and I'm almost reluctant to sell it, knowing the buyer will get a bad sounding unit.
Looks like the budget Class D Yamaha would be the PA2030: https://asia-latinamerica-mea.yamaha.com/en/products/proaudio/power_amps/ma_pa/index.html. Would be interesting to see how that performs.

I don't want to spend thousands, but I'm more interested in Class D for space on my desk than for cost, so I wouldn't mind paying a bit of a premium for something well made.
 

bigx5murf

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#48
Been looking for a good budget amp, I have a decent set of speakers I think in a pair of Monitor Audio Radius 45 bookshelf speakers (correct me if I'm wrong, I can invest in a new pair of speakers if there are better for not too much more) for nearfield listening at my desktop. Going to by a separate dac and amp, but not sure what amp to get. I got a cheap 50x2w amp that sounded WAYYY worse than my old lepai 15x2w amp so I went and refunded that. Scared to buy a crap amp again. I am a college student and don't have too much cash on hand, so I'd prefer something under $100. I dont care about stuff like tone control, etc, or even volume if the sound is going to be fine just being controlled from my pc or a DAC. What's the best amp under $100?
Not to be rude, but I've owned the MA Radius 90, 200, and the old bottom firing subwoofer. In terms of build quality, these were excellent speakers (mine were bamboo finish, and it was gorgeous). But they are by virtue of their size, "lifestyle speakers", and performance is very limited by their size. They were inefficient, really needed a subwoofer, and needed to be crossed over quite high.

I see the link for your speakers, and notice they have the tweeter on the rear. This means they're a dipole design, they're really meant more for ambient effect in a home theater setting as surround channels. Trying to bounce high frequency sounds off the rear wall isn't going to give you very good imaging performance there's no way around that. Using them on a desk is far from ideal. On a desk you'd want a 2 way with the woofer and tweeter as close together as possible, or even better a coaxial design.
 

bigx5murf

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#49
Following a phase of fascination with those "new" amps, I'm growing more and more disgusted by them, and the wild claims made about them by some resellers. A gain setting issue? That's unacceptable. The PA3 ain't exactly cheap either. For instance Yamaha amps start at about $150, new. You would never get an issue like this on a mainstream cheap amp.
https://www.audiosciencereview.com/...asurements-of-nuforce-sta-200-power-amp.5039/

Amir found the nuforce sta-200 to suffer from the same issue. At least there was a way to correct it on the cheap tpa3116 amp.
 
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#50
Speaking with a friend of mine which is an experienced reviewer he said that nuforce is made of incompetents that can't make a project right and when you make them notice their engineering mistakes they ban you from their forum. This just verify suspect i had, their products never convinced me.

Btw after buying it i suggest the allo+d. It surely has the premium feeling other class d are lacking
 
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#52
I think he had 1-2 piece of gear to review and what made him do these allegations is the fact that when he addressed the issues as a feedback he was kicked by every nuforce board without warning.
I mean this sound fishy. Like he exposed something the manifacfurer knows well but he doesn't want it to be shown. Maybe they lowered quality on purpose to raise profit.

It reminded me the same situation where nwavguy got banned from headfi for doing the same thing for schiit products, and since schiit is sponsoring that community, they banned him right away
 
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#53
I decided to sell the Topping PA3 afterall. I am now on the lookout for another option to fill my need of a stereo amp for the garage to drive a pair of Elac B6.2 speakers for winter spin classes etc.. I mention the class because output levels need to adjust up a bit to compensate for the collective sound of the bike trainers etc.. Garage is ~700 sq ft, finished in drywall and mostly empty. In the past I've used an SMSL SA98e amp (claimed 160wpc), and I may go that route again but I'm taking the opportunity to consider the other options. The SMSL is plenty loud with the volume never needing to exceed 50%. The other options that I'm considering are below:

Fosi TDA7498E - "160" wpc into 4ohm
Fosi BT20A. - "100" wpc into 4 ohm
Dayton APA150- "75. wpc into 4 ohm
Russound P75. - "75" wpc into 4 ohm.

My speakers are 6 ohm.

The first two I believe are claimed at 10% THD, which I wouldn't want to put my speakers through.

The Russound is larger and I believe has an internal power supply, and I only stumbled upon it this evening and the reviews seem very favorable. Does anyone here know anything about it? Is it a class D amp?

Also, the Dayton being an A/B amp, will it drive the speakers better and louder than a class D 75wpc amp? How should I make sense of wattage specs when many of these companies grossly over claim power?

The Topping PA3 had barely adequate power. My reason for selling was that the sound profile wasn't my favorite and in order to make it loud I was up near 90% on the dial. Also, another member asked about a dual input mini amp and I took the chance to pass it on and try to find a better fit.

-Jeremy
 
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#54
I just read that the Russound is in fact an A/B amp, so it may compare more directly with the Dayton apa150. Still hard to know how to compare class D exaggerated power to likely more realistic claims from the A/B options.

If the 80wpc Topping was barely adequate, are these two 75wpc A/B amp options not worth considering? Or is this an apples/oranges situation?

-Jeremy
 
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#55
Now I feel silly. One site said that the Russound was an A/B amp, but others say that it's a class D. And the amazon reviews aren't nearly as kind as the crutchfield reviews. Too bad if it's just a repackaged cheapo amp like the others. It was looking like a great option for a minute.

*edited to add:

Crutchfield's site also says A/B, and the manual states some amp clearances and heat concerns that would support this. Odd though because on another discussion forum someone was discussing how they bought a dead one and opened it up to repair the two "TDA72.." amp boards inside that had fried. That combined with the amazon reviews that call this a class D has me confused. Makes me wonder if there are multiple versions of this amp.

-Jeremy
 
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#56
I ended up with the Russound P75 from crutchfield in the end. It was cheaper than the Dayton at $130, and I figured buying from a US store would mean easier support during the warranty period if needed.

It showed up yesterday and it sounds really good to me. I first tested it on my Elac B6.2's and it didn't seem to be altering the sound in any bothersome ways. The bass seems less boomy than the Topping PA3, and the highs seemed similarly as crisp as on my pioneer AVR. Also the amp played significantly louder at 50% on the dial, as compared to the little PA3. The gain level was one of my concerns with the Topping, and I was very happy to find that I won't have to run this thing at redline ever. More than enough volume.

I then moved it to the garage where my BS22's are. Similar results there. It just sounded normal, as it should. My initial impression of the PA3 had been underwhelming compared with the SMSL amp I use out there, but the P75 sounded at least as good as the SMSL to me. All in all, I'm happy with the purchase and think that when I do hook this thing up permanently to the B6.2's, I won't have any regrets.

I know this is a thread about mini class D amps, and the russound is neither miniature, class D, nor an audiophile grade stereo amp.
Since one of the first reasons people buy class D amps is the low price, this P75 cost me all of $25 more than amazon's price for the Topping and at least to my ear it sounds significantly better.

Had it not been priced at $130, but rather the $200+ that it's selling for at BB, I would never have considered it. At $130, It's close enough to the 'higher wattage' class D amps that it was worth a look, and comparing it in that arena seems to be no contest.

-Jeremy
 
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JohnBooty

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#57
PA3(4ohm):
NA, because PA3 overheat before THD+N reach 1%
Huh, that note from Topping is a little concerning. Wanted to add some anecdotal testimony here about my experiences involving these amps and 4ohm speakers.

Last May, I gave my brother-in-law one of these Topping PA3 amps along with a set of these DIY speakers (the S2000 MTM kit) I built for him. Incidentally, those speakers are fantastic -- really an insane value. https://www.diysoundgroup.com/s2000-mtm-kit.html

Also, for the last few weeks I've been running my own PA3 with a set of desktop speakers the manufacturer rates as "4-8ohm" which I'm guessing means they're essentially 8ohm with a few big 4ohm impedance dips.

The good anecdotal news is that neither of us has experienced any sort of shutdown or overheating issues.

I'm guessing you'd have to run the amp near max output at 4ohm to trigger that. If I have time this weekend I'll see if I can make it happen and share my findings.

I'd also note that the color and dimensions of the PA3 case are identical to AudioScienceReview's favorite problematic darling DAC & headphone amp combo, the Topping DX3 Pro. They make a very attractive little stack together. :cool:

The PA3 has similar "marketing ratings" but uses an external brick power supply, which I think is witching, not linear
A witching power supply... ah, that explains the enchanting sound!
 

JohnBooty

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#58
In the past I've used an SMSL SA98e amp (claimed 160wpc), and I may go that route again but I'm taking the opportunity to consider the other options. The SMSL is plenty loud with the volume never needing to exceed 50%.

[...]

The Topping PA3 had barely adequate power. My reason for selling was that the sound profile wasn't my favorite and in order to make it loud I was up near 90% on the dial.
Definitely puzzling to hear since the PA3 uses a TDA7498E, just like the SMSL SA98. Did you compare the Topping PA3 and SMSL SA98 in identical conditions? In my experience Topping products are at least as well engineered as SMSL products, and usually much more so.

I've got a SMSL SA98 here too. I'll try and compare it head to head with the PA3 at some point, though I don't really have the tools for an objective measurement other than an SPL meter.

FWIW, the PA3 + S2000 MTM speaker combo put out loads of volume and strong bass for me. However, the S2000 MTM is a high efficiency design and puts out some strong bass even with weaker Class D amps, so maybe that was sort of a best case scenario.

Following a phase of fascination with those "new" amps, I'm growing more and more disgusted by them, and the wild claims made about them by some resellers. A gain setting issue? That's unacceptable. The PA3 ain't exactly cheap either. For instance Yamaha amps start at about $150, new. You would never get an issue like this on a mainstream cheap amp.
Cheap class D amps can be a great value as long as you understand what you're getting.

Yes, you trade off some maximum output in favor of compact form factor and blessed simplicity.

Yes, the power ratings are a pure marketing fantasy since they're given at 10% distortion. Rule of thumb is to simply divide them by 2 to get a power rating that is remotely comparable to an FTC-compliant rating on a good old fashioned Class AB amp. This is only a 3dB difference in headroom however so I don't think it's the biggest deal in the world.

For small rooms, modest amps like the SMSL SA50 provide more than enough clean power unless using hard to drive speakers. For medium rooms, I'd say the same of higher-powered cheap Class D amps like the SA98 and PA3.

The PA3 ain't exactly cheap either. For instance Yamaha amps start at about $150, new. You would never get an issue like this on a mainstream cheap amp.
I spent some time with the Yamaha S201 (or was it the 202?) which has an MSRP of around $150 and it's not great. I mean, it's totally adequate, and gives you features like an AM/FM tuner. It's also suspiciously lightweight compared to AB amps of yore, so we can be fairly certain this thing is not exactly a juggernaut when it comes to power delivery.

IMO really nice Class AB amps start well above $150. I'd take my Emotiva A-100 over any of my cheap class D amps, but that has an MSRP of $229. These Class D amps fill a niche well below that price point.
 
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#59
Hi, just joined after a friend who got me to buy a Topping D30 told me about this site!
I needed an office Dac/Amp, and was hoping that some under 300 CDN combo like discussed in this thread would have worked (for just-purchased Q Acoustics 3010s), but alas! Really still need the small form factor, though, so sprung for a used NAD d3020 v1. I have liked NAD stuff in the past alright (going back to my 3140 in 1981!), so hopefully it will be better than the Topping/SMSL amps, and includes a DAC for not that much more money. I also have a Bantam Gold for another small system, and like the sound of it a lot (it replaced a horrible Topping amp from years ago whose model I forget, as I gave it away), but it is limited to one input. Would like to see more development small form factor amps if getting decent sound out of them is possible at a reasonable price—the NAD and Bantam Gold werenn't cheap cheap :)

Cheers and thanks for all the work. This site is amazing, and threatens to steal my whole day away going down rabbit holes!
Bill in Ontario, Canada
 

somebodyelse

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#60
Really still need the small form factor, though, so sprung for a used NAD d3020 v1. I have liked NAD stuff in the past alright (going back to my 3140 in 1981!), so hopefully it will be better than the Topping/SMSL amps, and includes a DAC for not that much more money.
NAD used a 30W Hypex UcD amp in the d3020 according to press around release, so it probably measures pretty close to ucd32-oem. Unfortunately the plots in their datasheet aren't directly comparable with those on this site, or as extensive as the more expensive models. It's clearly not up to the level of the UcD180, let alone the nCore amps, but that's hardly a surprise given the price.
 
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