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

[graz_lag]

I like the current way, it encourages you to look at the graph and not a single number.

Yeah, exactly as Mr. Lyngdorf looks at the graph of his business's sales and not to the single measurement numbers of this broken unit of his ...

 

[graz_lag]

I agree with your point as to the value of the name brand and what it represents. Also, features, cosmetic appeal, etc. all have a value that may be out of synch with the price for many, and that's fine if there continues to be a market for that.

But I think the main point is what this website has shown us is it's not all that expensive to make a well measuring and performing product. Surely within that $6500 price there is room and resources available to apply basic engineering principles to achieve good/great measurements in addition to everything else?

If I splurge on a Ferrari, I know I have a beautiful car. But, I don't want to get beat at a light by the Corolla next to me (not that I race cars at stoplights, but you get the point). Amir's measurements are bringing this out into the light for all to see wheras it wasn't really obvious before.

You are breaking into somebody's open door ... (this is how we say it here in France ...)

 

[Samoyed]

Uh, what would Jerry Lewis say?

 

[graz_lag]

Uh, what would Jerry Lewis say?

Simply laughing ...

 

[restorer-john]

Clipping isn’t the actual issue, it’s audible distortion.

You are missing my point. The onset of visible waveform clipping has been used for generations to determine the maximum power an amplifier can produce.

The hockey stick by definition rises quickly over a sample or two.

The power output samples are too few, and far apart to determine accurate available power at the point of clipping.

I would have to hugely increase the resolution here to have more points which makes the test much slower and also keeps the amplifier in clipping region much longer which may damage it.

Anyway, if there is strong feeling about this I will create the correct test and run it.

In 40 years I've never damaged an amplifier from having it sit right on the edge of clipping. Wind it up to the limits, view the trace and back it off until you see no flat topping or rail modulation on the waveform. At the same time, look at your FFT in real time, take some THD readings and a calculated maximum power value.

Then back it down to rated power and do THD testing to confirm manufacturer's specifications.

 

[Sander_web]

I can understand your disappointment given the good reputation Lyngdorf has, however this is the first independent measurement I've come across of their equipment. Since this is a user driven community and considering your questions whether the DUT was faulty or not I suggest you offer your unit being measured @ASR, of course @amirm needs to agree.

Unfortunately, I live in the Netherlands, so this would be a very costly exercise. May be curious US-owners feel for this. And if I understood it right, Amir's company is a Lyngdorf dealer. If so, it won't be difficult for him to get his hands on a demo unit.

 

[Sander_web]

I test a lot of products that don't do well. Some manufacturers like Benchmark contact me, send me a second unit and help resolve the issue. Some don't care or don't know. In latter cases, it is assumed it is not an issue for them.

The least costly path by the way is for the manufacturer to run the same tests and publish them. Since my analyzer is industry standard, there is good chance they have similar units and we can help resolve differences. Unlike magazine reviews, my tests are interactive and I am happy to continue to test and help get to final answer. That is what I say at the end of every review.

Until then, yes, it is a sample of one. It is the nature of reviews of expensive products that we test only a single sample. If you or someone else owns the same unit, feel free to send it to me and I will test that.

Finally, I want to make sure you know that this is not "abnormal results." What is there is switching amplifier noise that is too close to audible band. This is the nature of the design. It is alarming to people maybe because until now, they did not know this since no one had measured any units. I consider the results disappointing but not abnormal.

Don't get me wrong, I think it is very good that these kind of reviews are performed. I am only questioning some aspects of the approach. You expected a certain outcome - based on years of experience as you say - got opposite results but didn't dive deeper in possible causes before publishing and possibly do unjustified damage to a brand.

You didn't answer one of my questions. Repeated below. I am interested in your answer.

"I have another question: how serious are you investigating the product at hand before you start your measurements? I ask because of before-mentioned ICC function. But I also like to know if you checked if you had the latest firmware version and - more important - checked if you disabled the Wifi and Bluetooth modules. These modules are build in for convenience (to create the ultimate all-in-one) but they are heavy noise injectors when enabled so not advisable for critical listening."

 

[MZKM]

You are missing my point. The onset of visible waveform clipping has been used for generations to determine the maximum power an amplifier can produce.

Not in the specs of most modern amps; 0.05%, 0.08%, 0.1%, and 1% THD make up around 80% of the specs I see.

All I want to know is how much wattage I can get for my music/movies without audible distortion, and 0.1% is a somewhat arbitrary, but semi-common spec that would be inaudible even if it was mostly higher order distortion.

 

[amirm]

"I have another question: how serious are you investigating the product at hand before you start your measurements? I ask because of before-mentioned ICC function. But I also like to know if you checked if you had the latest firmware version and - more important - checked if you disabled the Wifi and Bluetooth modules. These modules are build in for convenience (to create the ultimate all-in-one) but they are heavy noise injectors when enabled so not advisable for critical listening."

Honest answer is that "not a ton." I test devices as members are using them. In this case knowing there were potentially DSP curves in there, I did a reset. Usually this all works well but if it doesn't, members ask me and I remeasure.

As to firmware, I dread changing firmware on member units. Sometimes the machine can get bricked, or not be downgradable should the member like it better with previous firmware. But again, I have made exceptions and upgraded devices as I did recently with an NAD unit.

As to bluetooth, etc. they better not be bleeding into the rest of the unit in devices this expensive.

 

[amirm]

Not in the specs of most modern amps, 0.05%, 0.08%, 0.1%, and 1% THD make up around 80% of the specs I see.

That's because manufacturers don't want you to know the onset of clipping point as that always produces less power than numbers they use.

 

[Samoyed]

You are doing a real service for consumers. Reasonable people can and will disagree on the meaning of your data, but I, for one, had misgivings about the value of this product. While it was mere suspicion, for me that has been corroborated.

 

[Deleted member 65]

Unfortunately, I live in the Netherlands, so this would be a very costly exercise. May be curious US-owners feel for this. And if I understood it right, Amir's company is a Lyngdorf dealer. If so, it won't be difficult for him to get his hands on a demo unit.

I support @amirm keeping a firewall between ASR and his private business, mixing the two is not a good idea.

 

[Deleted member 2348]

amirm: Did you or could you please measure phase response and/or group delay from 20Hz to 20kHz on the speaker outputs? Does RoomPerfect still have the "bump" in group delay around 500Hz?

Edit: Group delay of the Lyngdorf DPA-1:

 

[BYRTT]

@paschulke2,

Nothing wrong with that bumb its standard behavour for textbook slope minimum phase filters, in your plot it looks something close to say 4th order high pass at 20Hz and a 16th order low or high pass at 500Hz and guess you asked unit set those filters yourself. That standard textbook filter slope set into unit will change to some other slope when summed with whatever acoustic response is of a real world transducer, and if you don't like the bumb and overall delay then use linear phase filters.

 

[MZKM]

@paschulke2,

Nothing wrong with that bumb its standard behavour for textbook slope minimum phase filters, in your plot it looks something close to say 4th order high pass at 20Hz and a 16th order low or high pass at 500Hz and guess you asked unit set those filters yourself. That standard textbook filter slope set into unit will change to some other slope when summed with whatever acoustic response is of a real world transducer, and if you don't like the bumb and overall delay then use linear phase filters.

Also, it’s within 7ms, so it won’t have an audible effect.

 

[amirm]

amirm: Did you or could you please measure phase response and/or group delay from 20Hz to 20kHz on the speaker outputs? Does RoomPerfect still have the "bump" in group delay around 500Hz?

I am performing listening tests right now so can't run any measurements. From what I can tell, it uses two different sweeps and most likely filtering schemes for low to mid and mid to highs. The stitching of the two may create some anomalies in the overlapped region.

 

[amirm]

Testing of RoomPerfect is complete. See: https://www.audiosciencereview.com/...measurements-of-lyngdorf-roomperfect-eq.6799/

 

[JJB70]

Hey, it's $6,500, it must be good!

 

[Deleted member 2348]

@paschulke2,

Nothing wrong with that bumb its standard behavour for textbook slope minimum phase filters, in your plot it looks something close to say 4th order high pass at 20Hz and a 16th order low or high pass at 500Hz and guess you asked unit set those filters yourself.

No. This was measured with a DPA-1 without any correction or tone control. The increase at low frequencies is caused by a low-frequency high pass (which can not be switched off) – that's correct.

The bump at 500Hz is caused by the fact that the DPA-1 splits the signal in two bands (<500Hz and ≥500Hz), reduces the sample rate for the lower band to reduce the DSP load for the EQ (e.g. for high-Q room modes), then performs the RoomPerfect EQ for both bands, samples the lower band up and joins the two bands again. This is (was?) done with minimum phase (IIR) filters and causes the bump. For the DPA-1 this is true even if RoomPerfect is off. The bump is always present. It can even be easily seen with a 100Hz square wave and a scope.

Also, it’s within 7ms, so it won’t have an audible effect.

If you run a speaker with a minimum phase (analog) cross over in the same range the two "bumps" will add up and might be higher than the threshold of audibility.

 

[JohnPM]

AES17 uses THD+N of -40 dB (1%) as the limit to establish the maximum input level and maximum output level of digital devices that can be expected to exhibit hard clipping. A similar approach can be used for power amplifiers (Crown do it, calling it the "Maximum average power" test) but more commonly amps are specified with a THD figure at their rated power, like the specs for the old 250MR I posted a while back: