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Review and Measurements of Lyngdorf TDAI-3400 Amp & EQ (Part 1)

amirm

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As you were not familiar with Peter's audio empire, you may like to know that in addition to the companies he owns, he also is a co-owner of Purifi ApS along with Bruno Putzeys and Lars Risbo.
Wonder what Bruno thinks of the amplification in Lyngdorf.....
 

amirm

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March Audio

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That maybe made sense 20 years ago. Today, people have high-resolution content and they like to think what they get above 20 kHz is what is in the music, not a heap of ultrasonic noise. Here is the fact sheet from Lyngdorf on TDAI-3400:

View attachment 22154

Over USB it supports sampling rates up to 384 kHz. That would give us a bandwidth of 384/2 = 192 kHz. Yes, usually that is more limited in practice so let's round that down to 100 khz. You are telling me that I am not entitled to any of that between 20 kHz and 100 kHz?

The notion that I should put filters in measurements to produce conditions that do not match what users have is just wrong in my book. I am not here to bend to what the product limitations are. I have tested many other switching amplifiers without the condition you mention.

In this day and age, high-end products must be able to reproduce high-resolution content. There is no reason to make excuses for it because the designer chose an architecture that doesn't work right there.

Even if I were to do as you say, there better be documentation to this effect. It needs to say that this product produces tons of ultrasonic distortion above 20 kHz so it is not suitable for high-resolution audio and such. If we are going to hide this, then the consequences are that reviews like mine come out and people are shocked to read it for the first time. As it seems to have happened.
Whilst I understand the reasoning for your view that amps should be able to reproduce high resolution content, the reality is that few recordings have any ultrasonic content, few speakers have any ultrasonic output and of course we can't hear it anyway.

It's interesting to look from an engineering perspective, we want to see clean but what's the real world consequence if it isn't?

If it is a dac then I'm concerned with ultrasonic garbage as it can negatively affect the following amp. However an amp far less concerned. The speaker is an electrical and mechanical filter.

Not condoning or defending this amps poor performance BTW, the US garbage is too close to the audio band. It's just a more general point.
 
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amirm

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Whilst I understand the reasoning for your view that amps should be able to reproduce high resolution content, the reality is that few recordings have any ultrasonic content, few speakers have any ultrasonic output and of course we can't hear it anyway.
This is a high-end product. Its target market believes and expects it to faithfully reproduce high-resolution content. I have a ton of content with valid response above 20 kHz. The TDAI-3400 says it can play up to 384 kHz sampling rate. If it can't do that properly, then it needs to be known to its customer base as they make their purchase decisions. That is what my review does.

Another point is why? Why should the customer settle for this after spending so much when alternatives don't impose the same?
 

March Audio

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This is a high-end product. Its target market believes and expects it to faithfully reproduce high-resolution content. I have a ton of content with valid response above 20 kHz. The TDAI-3400 says it can play up to 384 kHz sampling rate. If it can't do that properly, then it needs to be known to its customer base as they make their purchase decisions. That is what my review does.

Another point is why? Why should the customer settle for this after spending so much when alternatives don't impose the same?
Totally agree with the premise that if the product says it does then it should.

However we both know that most hi rez content has little useful musical information into the ultrasonic range. So I disagree with you there.

Anyway, the point was wider than that, and it certainly wasn't a criticism of the review. It's more about the fallacy of high rez (high bandwidth) content and the simple point that you can't reproduce it or hear it even if it is there.
 
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Tip

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I don't write books or lengthy paid reviews. My reviews are brief and follow similar measurements and techniques across same class of products. So regular readers can follow what is being done. I realize you are new so not as familiar with them. The answer to that would be to ask clarifying questions, and not assuming I don't know what a switching amplifier is and how to measure it.
For example, instead of writing "Audio Precision software decided to just show a DC measurement in the scope graph and would refuse to give me a reliable power measurement. I was going crazy until I realized there was fair bit of DC leakage out of the unit. So I told the AP to use AC measurement and that all of a sudden cured the problem..." and posting graphs, you could have just written, "Each channel of the TDIA-3400 operates in bridged mode." More information, less writing. (Sounds like a beer commercial ;))
 

levimax

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Totally agree with the premise that if the product says it does then it should.

However we both know that most hi rez content has little useful musical information into the ultrasonic range. So I disagree with you there.

Anyway, the point was wider than that, and it certainly wasn't a criticism of the review. It's more about the fallacy of high rez (high bandwidth) content and the simple point that you can't reproduce it or hear it even if it is there.
I am not worried if I hear the US noise it's self but wonder how it effects the tweeters performance in the audible range... all that energy is doing something... what I don't know. Amir can you do some testing of something like a tweeter being fed a 12 KHz tone with and without US noise and see if there is any measurable difference?
 

amirm

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For example, instead of writing "Audio Precision software decided to just show a DC measurement in the scope graph and would refuse to give me a reliable power measurement. I was going crazy until I realized there was fair bit of DC leakage out of the unit. So I told the AP to use AC measurement and that all of a sudden cured the problem..." and posting graphs, you could have just written, "Each channel of the TDIA-3400 operates in bridged mode." More information, less writing. (Sounds like a beer commercial ;))
I could if the two statements were equivalent but they are not. There is no requirement for AC coupling with differential inputs.
 

amirm

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Amir can you do some testing of something like a tweeter being fed a 12 KHz tone with and without US noise and see if there is any measurable difference?
Sure but can't do it right now. Acoustic tests are hard because my lab is above our living room so no isolation of noise, etc.
 

Tip

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I own a TCS MK ii. It started to have problems after being upgraded for $5,000 to Mark ii. This was on top of original $10,000 purchase price (total $15,000). I downloaded new firmware from Tact website which bricked the unit. Contacted Boz and he told me to get lost because the unit was discontinued and I had no business upgrading its firmware.

I also tested an RCS 2.0 my chief designer has (see: https://www.audiosciencereview.com/...s/a-deep-dive-into-hdmi-audio-performance.56/). So my familiarity with their technology goes way back. Sadly though it is not a positive one outside of the room equalization.
Sorry to hear about your TCS mkII. Boz could be a real jerk some days -- you had to catch him on a good day. Are you a member of the TacTAudioUsersGroup (I'm a moderator) on Yahoo Groups? We may be able to help you get it working (that's practically all I do anymore.) I've created a library of the latest valid TacT software/firmware files and manuals on my personal cloud storage (they're too big to store on the group.) Unfortunately our TacT hardware expert isn't participating anymore.

Thanks for the link to the RCS 2.0 jitter test. You do know that the RCS is still doing room correction even in Bypass Mode -- it just loads a flat correction filter and performs the convolution on the input through the DSPs. Plus the clock is powered directly by the 5V of the SMPS instead of the output of the voltage regulator. (P.S. I was a little surprised that you with your background in software didn't mention that the samples are in 2's Complement format.;))
 

Blumlein 88

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Sure but can't do it right now. Acoustic tests are hard because my lab is above our living room so no isolation of noise, etc.
If you do this at high enough level long enough you'll get no noise from the tweeter. Be careful there.
 

amirm

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amirm

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If you do this at high enough level long enough you'll get no noise from the tweeter. Be careful there.
Yeh, was not planning to use my main system.
 

svart-hvitt

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Well, correctly specified THD for amplifiers (since the 1974 FTC guidelines) is from 250mW to rated power, 20Hz-20KHz.

A single THD at rated power is meaningless and deceptive.

Typical examples of correctly rated gear (headline number service manual):

View attachment 22083

Notice the FTC rating on this example below has a slightly higher THD than the full power number as THD starts off higher at low powers and decreases towards maximum.

View attachment 22084

View attachment 22085

Below are typical preamplifier THD ratings:

View attachment 22086

View attachment 22089

Phono stage:

View attachment 22087

Line stages:

View attachment 22088

View attachment 22090

View attachment 22091
View attachment 22092

View attachment 22094

Notice the DIN power in the above examples at 1%THD at 1KHz and 4ohms. Nobody ever considered the EU DIN (or the IEC) ratings as anything useful back in the day. The only serious rating was the FTC and all the respectable manufacturers who wanted to sell gear in the US had to adhere to it. Now we have a global marketplace, with little impediment to importing gear directly. Stuff without c-tick, UL listings, etc. It's a nightmare.

Standards have lapsed to the point where specifications are a sad joke, and not to be trusted, and in many cases, blatantly deceptive and designed to paint their products in the best light as opposed to the old way, which was a worst case scenario.

The random examples above are from Denon, Yamaha, Pioneer and Sony and all those pieces are in my collection. They go to show that standards have not only lapsed across the board, but gone backwards a long way. All those pieces above are >20-30 years old...
@restorer-john , seems like your remark on the state of amplifiers going backwards is reflected in industry groups as well:

https://www.ceoutlook.com/2019/01/30/stricter-amplifier-ratings-proposed/

It remains to be seen if stricter standards are really on its way.
 
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