# Topping LA90 Review (Integrated Amplifier)

## Rate this amplifier:

• ### 4. Great (golfing panther)

• Total voters
631

#### peng

##### Major Contributor
Forum Donor
Nonsense, you do not know what you speak about. See output coils at the posted photos.

Ignoring capacitive reactance, take a look of the formula

or take capacitive reactance into account, though for amps that probably wouldn't be significant:

By the way, you are the one who posted a formula to begin with. I never challenged that at all, just wanted to be clear on the terminology part, i.e. resistance vs impedance. So can we have a discussion without being rude anyway?

Okay if someone posted photos of some output coils for the LA90 then I obviously missed. Still, my point simply is, impedance includes the effects/contribution of the inductive reactance anyway so the specified output impedance should be the total. The only thing is, Topping should have included the frequency at which it was calculated, and/or measured as we all know DF is not constant over the 20-20,000 Hz range.

If Topping output impedance spec include the resistive components only then they should have called it output resistance.

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#### Vini darko

##### Major Contributor
Here's Wolf's measurment of output impedance. So the speculation can stop.

#### KSTR

##### Major Contributor
As expected, @pma's guesstimate of ~22uH coil was spot on:
|Z| = 2pi * f * L ==> L = 0.04 / (6.28 * 20000) = 32uH. I discarded the small R contribution here (will be less than few %). You can go full Pythagoras if you want on your own ;-)

#### tritopia

##### Member
How I feel about the PA5 and LA90. Short feeling for a short period of time.

* PA5 - "It's a sound that is possessed by recording and mixing engineers. It's refined, smooth, balanced and accurate."

* LA90 - "It's a sound that is possessed by the performer. It's emotional and deep. It's a sound that doesn't lose its balance and precision."

#### Talisman

##### Active Member
Forum Donor
How I feel about the PA5 and LA90. Short feeling for a short period of time.

* PA5 - "It's a sound that is possessed by recording and mixing engineers. It's refined, smooth, balanced and accurate."

* LA90 - "It's a sound that is possessed by the performer. It's emotional and deep. It's a sound that doesn't lose its balance and precision."

View attachment 206917
Yet the measurements say they should sound exactly the same. Without terms of fantasy.
They amplify the input signal perfectly. Stop

#### tritopia

##### Member
Yet the measurements say they should sound exactly the same. Without terms of fantasy.
They amplify the input signal perfectly. Stop
I agree. It's just a short feeling.

#### daniboun

##### Addicted to Fun and Learning
Yet the measurements say they should sound exactly the same. Without terms of fantasy.
They amplify the input signal perfectly. Stop

Do you own the PA5 ? do you own the LA90 ? I have both in addition to the Purifi and many other class D....
The measurements highlight their ability to transmit a "clean" and "transparent" signal, however, they absolutely do not have the same sound signature.

#### VintageFlanker

##### Major Contributor
Forum Donor
The measurements highlight their ability to transmit a "clean" and "transparent" signal, however, they absolutely do not have the same sound signature.
Because you say so?

How on Earth two units being able to "transmit a transparent signal" would have different sound signature?

#### daniboun

##### Addicted to Fun and Learning
Because you say so?

How on Earth two units being able to "transmit a transparent signal" would have different sound signature?

Simple question : do own both amp ? "signature" is probably not the best word but the PA5 and LA90 do not sound the same way !

I'm going to do something cool, I am going to ask Amir to listen to his LA90 + Revel F226BE speakers and let him come back to us)

#### Talisman

##### Active Member
Forum Donor
Do you own the PA5 ? do you own the LA90 ? I have both in addition to the Purifi and many other class D....
The measurements highlight their ability to transmit a "clean" and "transparent" signal, however, they absolutely do not have the same sound signature.
If they have a different "sonic signature" then they are NOT transparent.
If two amplifiers give recognizably different sounds, obviously one of the two is not perfectly amplifying the input signal.
These two amplifiers according to all measurements, given an equal input signal, have a threshold of transparency well beyond the audibility limit and show no variance to the load, so they cannot sound differently, if they do something wrong, in the samples or in the measurements.
Let's stop playing these myths

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#### VintageFlanker

##### Major Contributor
Forum Donor
I'm going to do something cool, I am going to ask Amir to listen to his LA90 + Revel F226BE speakers and let him come back to us)
Amir doesn't own F226BE, or I missed something.
Simple question : do own both amp ?
I do not. None are powerful enough to be anywhere on my radar to be honest... But I tested, like you did, many, many, class-leading D amps and found no audible difference, apart from their abilities to drive difficult speakers depending on SPL required.

#### Selkirks

##### Member
The LA90 and PA5 certainly don't sound the exact same, but I found the PA5 almost indistinguishable from the Aiyima A07.

#### tritopia

##### Member
Because you say so?

How on Earth two units being able to "transmit a transparent signal" would have different sound signature?
ASR reported that the performance indicators of both amplifiers were very good. Yes. I agree.
However, the two amps sound quite different.

Is this result strange? Is it impossible to reconcile these two results?

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#### Sokel

##### Addicted to Fun and Learning
The first thing I did when I tested my amps on my active set-up was switch them over.
Yes,the 300a2 looks much better on paper in terms of SINAD,etc but any difference between this and to 1200as2 occurred only when I cranked up the volume to the point no sane person would do.
If two amps that on paper seem transparent sound different I would search for the defective unit or the defective condition.

#### Talisman

##### Active Member
Forum Donor
The LA90 and PA5 certainly don't sound the exact same, but I found the PA5 almost indistinguishable from the Aiyima A07.
This is paradoxically stranger, as the Aiyima A07 admittedly suffers from load dependence, which is why it is more likely to be "different".
If you don't hear a difference between pa5 and A07 you should hear even less between pa5 and LA90

#### JSmith

##### Major Contributor
This is ASR... if members claim they can hear a difference between two transparent devices, it is encouraged that said members conduct reasonable blind testing and post some solid results to support their assertion. Otherwise it is nothing to anyone else apart from potential hearsay and opinion.

JSmith

#### pma

##### Major Contributor
This is ASR... if members claim they can hear a difference between two transparent devices, it is encouraged that said members conduct reasonable blind testing and post some solid results to support their assertion. Otherwise it is nothing to anyone else apart from potential hearsay and opinion.

JSmith
Basically I agree, but how do you define and evaluate the "two transparent devices"? I hope not based on 5W/1kHz/4ohm SINAD number.

#### daniboun

##### Addicted to Fun and Learning
This is ASR... if members claim they can hear a difference between two transparent devices, it is encouraged that said members conduct reasonable blind testing and post some solid results to support their assertion. Otherwise it is nothing to anyone else apart from potential hearsay and opinion.

JSmith

This is a Cartesian and almost peremptory answer in the sense that if we rely on ASR measurements, there would be almost no point in buying the LA90 and even less an AHB2.... If measurements take precedence over emotions, you might as well buy a PA5 without asking questions....

I realize that many people who have never owned the PA5, or even the LA90 or the Purifi manage to give an objective opinion by taking into account a measurement test as an absolute basis for reasoning...

I could be wrong but that's my way of looking at things )

#### daniboun

##### Addicted to Fun and Learning
Basically I agree, but how do you define and evaluate the "two transparent devices"? I hope not based on 5W/1kHz/4ohm SINAD number.

Very good question ! I asked Amir to give me his feelings on a practical listening PA5 + Revel F226BE + Topping D90SE VS LA90 + Revel F226BE + Topping D90SE. If in theory the two setups are almost as transparent, there should be practically no difference in listening for purists.

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#### Talisman

##### Active Member
Forum Donor
This is a Cartesian and almost peremptory answer in the sense that if we rely on ASR measurements, there would be almost no point in buying the LA90 and even less an AHB2.... If measurements take precedence over emotions, you might as well buy a PA5 without asking questions....
Exactly, and this is precisely the basis of my dispute with the product (in the initial pages)

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