• 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). There are daily reviews of audio hardware and expert members to help answer your questions. Click here to have your audio equipment measured for free!

Topping PA5 Review (Amplifier)

Crosstalk

Senior Member
Joined
Dec 13, 2021
Messages
416
Likes
207
Well, I do not know any class D chip amp that can drive lower than 2ohm. We know this one is a class D chip amp and it is bridged. So it does not driver lower than 4ohm.



I did not imply that. However the power that the AHB2 can deliver is even underestimated a bit. The power delivered by the PA5 is a bit overestimated, just because the power supply cannot deliver 250W (2 x 125W in 4ohm).



Nope. Hard loads are usually when you drop quite low (lower than 4ohm, way lower than that) in the bass register. Then you need a lot of current. Many sweet sounding amps just sag, then. Those situations need muscle. The Infinity Reference 253 just need an amp with a response that does not depend on the impedance at a given frequency, not a muscular amp.
Isn’t the powersupply bundled 300w?
 

Moosi

Active Member
Joined
Feb 5, 2021
Messages
201
Likes
99
MA12070 can go down to 1.6 ohm in PBTL. No problem driving LS50 Meta with a SabajA20a.
 

jlesterp

Active Member
Manufacturer
Forum Donor
Joined
Jan 16, 2021
Messages
117
Likes
172
Location
Philippines
Oh, then I stand corrected, there is indeed one case where you can hit 3ohm in BTL!
You can load 2 ohms in TPA325X in BTL mode, but the output stage is current limited so you'll get less power (it will clip / protect with less voltage swing in 2 ohms)

Which means if you are just listening in a small room with moderate sound levels, you don't need to worry from impedance dips with some speakers. The case will be different in loud listening sessions since peak power in 2 ohms can be easily hit by some music transients.
 
Last edited:

BoredErica

Addicted to Fun and Learning
Joined
Jan 15, 2019
Messages
564
Likes
783
Location
USA
Well, I do not know any class D chip amp that can drive lower than 2ohm. We know this one is a class D chip amp and it is bridged. So it does not driver lower than 4ohm.
Nope. Hard loads are usually when you drop quite low (lower than 4ohm, way lower than that) in the bass register. Then you need a lot of current. Many sweet sounding amps just sag, then. Those situations need muscle. The Infinity Reference 253 just need an amp with a response that does not depend on the impedance at a given frequency, not a muscular amp.
Okay, I think I see now. I think in your original post then you were only talking about impedance and how difficult speakers may be to drive. I had FR variance on my mind.

I'm not sure what 'doesn't drive lower than 4ohm' means. That wording is black and white. If I get a pa5 and I hook up LS50 Meta, the amp clips no matter no matter what? Because if it cannot drive lower than 4ohm you're basically saying this product is trash because plenty of speakers dip a bit below that.
 
Last edited:

mocenigo

Major Contributor
Joined
Dec 8, 2018
Messages
1,004
Likes
761
Okay. I think in your original post then you were only talking about impedance and how difficult speakers may be to drive?

I'm not sure what 'doesn't drive lower than 4ohm' means. That wording is black and white. If I get a pa5 and I hook up LS50 Meta, the amp clips no matter no matter what? Because if it cannot drive lower than 4ohm you're basically saying this product is trash because plenty of speakers dip a bit below that.

I also don't know what way lower than 4ohms is. 3? 3.5? 3.75? 2.5?

Correction: it may be 3ohms depending on the chip.

It may mean various things: that protections trip, or that available power decreases because of current limitations. The result is that it will lack dynamics- esp in the bass - and/or distort considerably, or will shut down earlier that one could expect.

It is not a SQ matter, but it restricts the type of speakers it can drive.
 

BoredErica

Addicted to Fun and Learning
Joined
Jan 15, 2019
Messages
564
Likes
783
Location
USA
It may mean various things: that protections trip, or that available power decreases because of current limitations. The result is that it will lack dynamics- esp in the bass - and/or distort considerably, or will shut down earlier that one could expect.
With no clipping indicator I would rather clipping be hard and obvious personally. Then from your POV, are you scratching your head on why people aren't testing amps at 3ohms?

Meta hits 3.7ohms and I am crossing over with a sub to relieve it somewhat. R3 closer to 3 but has higher efficiency.
 

mocenigo

Major Contributor
Joined
Dec 8, 2018
Messages
1,004
Likes
761
With no clipping indicator I would rather clipping be hard and obvious personally. Then from your POV, are you scratching your head on why people aren't testing amps at 3ohms?

Oh, they do. Often you read reviews of amps driving speakers that go very very low and with reactive loads. I expect Amir to have enough money to afford more than one pair of speakers, so I scratch my head on why he does not!
 

BoredErica

Addicted to Fun and Learning
Joined
Jan 15, 2019
Messages
564
Likes
783
Location
USA
Oh, they do. Often you read reviews of amps driving speakers that go very very low and with reactive loads. I expect Amir to have enough money to afford more than one pair of speakers, so I scratch my head on why he does not!
Same for wolf guy at L7Audiolab, the same 4/8ohm tests.
 

DanielT

Major Contributor
Joined
Oct 10, 2020
Messages
3,493
Likes
3,019
Location
Sweden - Слава Україні
Nope. Hard loads are usually when you drop quite low (lower than 4ohm, way lower than that) in the bass register. Then you need a lot of current. Many sweet sounding amps just sag, then. Those situations need muscle. The Infinity Reference 253 just need an amp with a response that does not depend on the impedance at a given frequency, not a muscular amp.
Hm but maybe a powerful PA amp at the bottom with a lot of current, which takes care of sub bass? Which is built like a tank to withstand tough battles (live, on the dance floor and so on). Which has a high damping factor, a lot of power, which can handle low ohms and so on. Okay, it may not be "nice" home hi-fi, but more about brutal power, but it's perfect for the lowest frequencies. In addition, it relieves the other amplifier then.:)

The crux is probably these damn fans, but if you can throw such a war horse into a closet (if you can solve it with cables) then the fan sound should be gone...maybe .... Just a thought.:)

It is possible, if they fit with power and efficiency, install quieter fans.

Edit:
By the way, this is the solution I am building together now. I am not the first to get a solution, rig based on it. PA amp plus subwoffers and maybe, maybe PA5 in the top speakers. I have to think about that.PA5 does not have the same quality in the highest frequencies as a well-built AB, but for me it does not matter. I have a built-in LP filter in me. As by the way, it also changes gradually year by year. :)

When it comes to subwoofers, it's more about NAF. Neighbor Acceptance Factor.

Edit:
Nothing new under the sun. Billy Gibbons explains how to combine two, 1:00 into the video. How the response, the answer should be in a sensible way 1:35 ..


Sorry, could not help but get a little silly.:)
 
Last edited:

Holmz

Major Contributor
Joined
Oct 3, 2021
Messages
1,512
Likes
879
Location
Australia

I did not imply that. However the power that the AHB2 can deliver is even underestimated a bit. The power delivered by the PA5 is a bit overestimated, just because the power supply cannot deliver 250W (2 x 125W in 4ohm).

Unless one is playing tones, most music has a crest factor of ~13 (maybe 5-6 with the loudness wars.)
So musically we can have 4W RMS, and 125W peaks… and not be clipping the peaks.

With loudness wars it is more like 30W RMS and 125W peaks.
 

AudioArchitech

Senior Member
Joined
Jul 10, 2021
Messages
307
Likes
225
Location
Canada
I find it hard to pick between a PA5 and Hypex NC252NP amp. It's not much more $ to get a Buckeye or Audiophonics... and there's way more power. SINAD, close enough. Also the new IcePower 200AS2 board looks interesting.
 

AudioArchitech

Senior Member
Joined
Jul 10, 2021
Messages
307
Likes
225
Location
Canada
Will I hear that noise? Not sure? Will the NC252MP give me more dynamics, bass slam... ? likely will. Could filter the lows out of the PA5, then the Pa5 likely wins in performance. splitting hair I know. When the volume is cranked, which one is going to be silent in between tracks. Has that been figured out and confirmed subjectively too?
 

Sudin

Member
Joined
Jun 20, 2021
Messages
7
Likes
5
That’s a little different—it’s a kit and the farts at Stereophile want to relive their memories of building Heathkit and Dynakit amplifiers in the 60’s.
There is fully-assembled version of AkitikA GT-102 ($499), not only kit version.
And AkitikA GT-102 is recommended in Stereophile's "Recommended Components 2021 Edition Two-Channel Power Amplifiers"
 

DanielT

Major Contributor
Joined
Oct 10, 2020
Messages
3,493
Likes
3,019
Location
Sweden - Слава Україні
There is fully-assembled version of AkitikA GT-102 ($499), not only kit version.
And AkitikA GT-102 is recommended in Stereophile's "Recommended Components 2021 Edition Two-Channel Power Amplifiers"
Speaking of kits and DIY.Here is an alternative if you want to fix, DIY. Service and recap on one like this and it will be really good.


It should be pointed out that the Amir test measures well but it may have to do with (full tuning before the rally track):

The work that Peter has done is exemplary. The inside looks brand new! I have repaired hundreds of amplifiers but never seen one this clean! So not only have the inside components been updated / replaced, but a lot of care has gone to cosmetically clean the unit. Peter sent me a long list of parts he has upgraded including reservoir capacitors and such. As a result, I do not know how representative of measurements are of stock units although probably not too far off. Used 2200 go for about US $ 530 on ebay.
 

Attachments

  • shot_2021-12-15_10-25-25.png
    shot_2021-12-15_10-25-25.png
    295.6 KB · Views: 55
Last edited:

nagster

Active Member
Joined
Jan 24, 2021
Messages
250
Likes
401
It is a 38V (not dual) 4A power supply. This makes it 152W. What am I missing?
According to JohnYang1997, practical (short term?) Is about 8A.
The AC adapter official specification 4A may be a continuous output guarantee value including strict conditions such as industrial use. Especially the temperature.
Of course, I think it is better to avoid continuous output for several hours at 4A or higher.
Perhaps the temperature of the amplifier will be the first limit.
 

tonycollinet

Major Contributor
Joined
Sep 4, 2021
Messages
3,221
Likes
4,780
Location
UK/Cheshire
It is a 38V (not dual) 4A power supply. This makes it 152W. What am I missing?
That @JohnYang1997 has said it is capable of delivering 300W. I think for a couple of minutes or so (but I'm sure he can correct me if I've got that wrong). At least more than enough for delivering peaks and crescendos in music.
 
Top Bottom