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Topping LA90 Review (Integrated Amplifier)

Rate this amplifier:

  • 1. Poor (headless panther)

    Votes: 35 4.4%
  • 2. Not terrible (postman panther)

    Votes: 50 6.2%
  • 3. Fine (happy panther)

    Votes: 193 24.1%
  • 4. Great (golfing panther)

    Votes: 524 65.3%

  • Total voters
    802

tomchris

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Well its got a separate DC power supply so no need for a many hundred Watt transformer and large reservoir caps.
Well, there is some merit in keeping the power supplies separate, I will give you that.
While the overall usefulness of large linear transformers and large reservoir caps can be disputed to some extent, I am certain that most users find these qualities both desirable and useful.
 

DualTriode

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So far this Topping amplifier is everything that I asked for. I use it for JBL D2 M2 Compression Driver / Wave guides crossed over at 2.2 kHz in a tri-amped system.

Even with my ear stuck in the throat of the horn I do not hear any hiss.

I much prefer the sound of a 3-way speaker with cone mid range driver.

Thanks DT

Related thoughts:

I am glad to see the voltage and current limiting parts of this design done outside of the power amp-chip. Overpower/heat limiting done by the typical power amp-chip sounds really bad.
 

daniboun

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System SINAD matters, individual DAC / amp doesn't mean that much. In this case DAC was the same but the amplifier with higher gain resulted in more noise which is not surprising. If a lower noise but lower output level DAC was used with the Purifi there would be less noise. The PA5 / LA90 need a higher output DAC as they have low gain. It's all about proper gain staging of components.

Michael

The LA90 has two-level gain settings with +6.7dB in low-gain and +19dB in high-gain mode.
 

Chrise36

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VS my Purifi (Kayamb OPA2210 buffers) VS my PA5: I wanted to know how well an AB amp mounted in the rules of the art could sound compared to a Class D amp mounted in the same rules of the art.
In all honesty I find the same "grain" that I had on my MOS-120 (MOSFET IRFP240 / IRFP9240) but with the surgery and righteousness of PA5 and Purifi.

What I noticed, I nitpick but I share it all the same: when I put my ears on my Seas Beryllium tweeter, the PA5 and the LA90 are absolutely silent, so that we have the impression that the amps are totally off. With my two Purifis, there is a very slight hiss, almost inaudible, but with your ears glued together you can hear it.

Now on the overall listening, the LA90 provides a lot of pleasure, I find it generally softer but that does not surprise me. Like I said, that's the feeling I've always had with Class AB amps.
Exactly the same noise issues with ncore dissapeared when i used an old Technics SU VX500 on my tweeters. Also felt softer drive with the speakers due to lower damping factor probably
 

DualTriode

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Weaker bass mainly and a feeling of less "intense" presentation.The Technics has very low DF vs the ncore btw.

This makes me scratch my butt and wonder if and how people think.

Damping factor is in the realm of damping resonance of woofers or other wobbly things.

Resonance in combination with reduced damping factor makes bass louder. Imagine that?

DT
 

Chrise36

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It seems Benchmark has proved this wrong:
This means that the amplifier output will decrease by 2.3 dB at 119 Hz when loaded by the speaker impedance.

But, near 3 kHz, our speaker input impedance is 18 Ohms.

  • The signal reduction at the 18-Ohm point will be 18/(18+0.8) = 0.957.
  • Converting to dB: 20*Log(0.957) = -0.3 dB
At a damping factor of 10, 119 Hz was attenuated by 2.3 dB while 3 kHz was attenuated by just 0.3 dB. The difference is 2.3 dB - 0.3 dB = 2 dB.

This means that there will be a 2 dB change in the overall shape of the frequency response curve when this set of speakers is driven from an amplifier with a damping factor of 10. The 2.3 dB loss of bass near 119 Hz is significant and should be noticeable under certain circumstances.
Btw
 

IPunchCholla

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Given the LA90 has a DF of well above 1500 what does that have to do with this thread? I'm loosing track what you all are talking about.
 

Bleib

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Given the LA90 has a DF of well above 1500 what does that have to do with this thread? I'm loosing track what you all are talking about.
Is this info available somewhere in these tests?
 

KSTR

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Is this info available somewhere in these tests?
Topping specifies 3mOhm which is reasonable for the topology used... at least for low frequencies where it matters. At high frequencies the series coil (for stability with capacitive cables/loads) increases output resistance as intended.
 

peng

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It seems Benchmark has proved this wrong:
This means that the amplifier output will decrease by 2.3 dB at 119 Hz when loaded by the speaker impedance.

But, near 3 kHz, our speaker input impedance is 18 Ohms.

  • The signal reduction at the 18-Ohm point will be 18/(18+0.8) = 0.957.
  • Converting to dB: 20*Log(0.957) = -0.3 dB
At a damping factor of 10, 119 Hz was attenuated by 2.3 dB while 3 kHz was attenuated by just 0.3 dB. The difference is 2.3 dB - 0.3 dB = 2 dB.

This means that there will be a 2 dB change in the overall shape of the frequency response curve when this set of speakers is driven from an amplifier with a damping factor of 10. The 2.3 dB loss of bass near 119 Hz is significant and should be noticeable under certain circumstances.
Btw

John Sian did not really prove anything wrong about the papers he quoted in that article. He simply highlighted some myths about DF as follow:

Myth - "Damping Factor Isn't Much of a Factor"

Myth - "A Damping Factor of 10 is High Enough"

Myth - "All Amplifiers Have a High-Enough Damping Factor"

Here's one of the paper he referenced, if you read the whole thing, you probably wouldn't hold Dick Pierce responsible for the myths JS cited, as JS himself said "READ THE PAPERS MORE CLOSELY!"


It seems to me it's a case when people, including Mr. Siau, tried to make their cases by emphasizing certain points. Mr. Pierce mentioned the benefits of higher DF, without identifying the details, probably because he wanted to debunk the one myth, that DF was such as major factor, and Mr. Siau appeared to be critical of Mr. Pierce paper, because he might have been trying to debunk the other myth that DF wasn't much of a factor. To me, both could have done better by reminding their readers not to jump to their own conclusion, unless and until they read the papers/articles in their entirety and understood the contents fully.
 

Chrise36

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John Sian did not really prove anything wrong about the papers he quoted in that article. He simply highlighted some myths about DF as follow:



Here's one of the paper he referenced, if you read the whole thing, you probably wouldn't hold Dick Pierce responsible for the myths JS cited, as JS himself said "READ THE PAPERS MORE CLOSELY!"


It seems to me it's a case when people, including Mr. Siau, tried to make their cases by emphasizing certain points. Mr. Pierce mentioned the benefits of higher DF, without identifying the details, probably because he wanted to debunk the one myth, that DF was such as major factor, and Mr. Siau appeared to be critical of Mr. Pierce paper, because he might have been trying to debunk the other myth that DF wasn't much of a factor. To me, both could have done better by reminding their readers not to jump to their own conclusion, unless and until they read the papers/articles in their entirety and understood the contents fully.
Have a read:
 

peng

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Have a read:

I read that more than once, to make sure I didn't miss anything in that article. The "myths" JS cited, and I quoted in my post were from that exact article.:D
 

restorer-john

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John Sian did not really prove anything wrong about the papers he quoted in that article. He simply highlighted some myths about DF as follow:



Here's one of the paper he referenced, if you read the whole thing, you probably wouldn't hold Dick Pierce responsible for the myths JS cited, as JS himself said "READ THE PAPERS MORE CLOSELY!"


It seems to me it's a case when people, including Mr. Siau, tried to make their cases by emphasizing certain points. Mr. Pierce mentioned the benefits of higher DF, without identifying the details, probably because he wanted to debunk the one myth, that DF was such as major factor, and Mr. Siau appeared to be critical of Mr. Pierce paper, because he might have been trying to debunk the other myth that DF wasn't much of a factor. To me, both could have done better by reminding their readers not to jump to their own conclusion, unless and until they read the papers/articles in their entirety and understood the contents fully.

None of Siau's 'papers' are anything more than self-serving marketing drivel. The crossover distortion article is arguably the most deceptive piece I have ever seen from any HiFi manufacturer, even in the bad old days. Thing is, they didn't need to resort to blatant deception to sell their amplifier- it was already good enough to sell on its own numbers. :facepalm:
 

IPunchCholla

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Is this info available somewhere in these tests?
Nope. Just from what Topping specs their output impedance. Given that at a DF of 10 we’re only talking about 2ish dB on speakers cherry picked to show an issue, I wouldn’t expect Topping to be off by the two orders of magnitude that would make this an issue.
 
Last edited:

pma

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We may expect Zout = 0.003 ohm + jwL
L = 2uH, w = 2 x pi x f
 

peng

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We may expect Zout = 0.003 ohm + jwL
L = 2uH, w = 2 x pi x f
Did Topping specify the 0.003 ohm as impedance? If they did, then 0.003 ohm would be it, no need to add jwl and/or j/wc because impedance includes inductive and capacitive reactances already.
 

pma

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Did Topping specify the 0.003 ohm as impedance? If they did, then 0.003 ohm would be it, no need to add jwl and/or j/wc because impedance includes inductive and capacitive reactances already.
Nonsense, you do not know what you speak about. See output coils at the posted photos.
 
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