100% agree!
The same about vinyl and RIAA preamps.
Who cares about the THD and SNR of the RIAA preamp when they are many times worse on the disc?
(Who cares about this vinyl anyway, if not for nostalgia?! SQ? Don't make me laugh.)
But people want it and buy it.
Alex.
It's all about marketing, profit etc.
Marketing needs references to compare products. THD, power, S/N and others are used for that.
It's easy to build electronics with very low distortion, but below some levels, it's pointless.
Let's think from the point of view of math and engineering.
Let's assume electromechanical devices have distortion around 0.5%, and when I say "around", it's because it varies a lot from 0.1% to 1% or even 2%.
If I sum 0.05% (just an example, it can be a bit less a bit more) on top of something that varies from 0.1% to 2%, it makes no difference in the final result, right?
Building any electronic apparatus with 0.05% such as pre-amp, power amp, DAC's etc, it's very easy and cheap.
So, there is no point of spending money, material, weight, special components etc on building electronics with much less that 0.05% if electromechanical devices are involved in the chain.
Now, let's think from commercial point of view.
The question is: how do I sell a RIAA pre-amp that costs US$40.00 for US$1000.00?
I start from what I want to profit and then I go find the numbers to position the product.
The main question is - why if speakers have X% THD, there is a difference between amplifiers with 0.X% or 0.0X%?
Alex.
Commercial reason. You can charge more for a 0.0X% than a 0.X% amplifier.
And there is nothing wrong with that. A THD 0.0X% amp is better than a THD 0.X%.
The point is: do you need that?
So, there is no sense to make THD in amplifiers and other things lower than that of speakers ?
Alex.
Alex.
You tell me.
See the chart below.
This is an actual THD of the lastest 3-way speaker I've built last year - it sounds great, by the way, beating some known brands in the market (opinion from other people on A/B comparison).
The chart has the original speaker THD (Blue line) plus 0.05% (RED line) and plus 0.001% (Green line).
0.001% is not even possible to see - it gets perfectly superposed on the original.
Would you pay good money to have the green line instead of the red line?
See the chart below.
This is an actual THD of the lastest 3-way speaker I've built last year - it sounds great, by the way, beating some known brands in the market (opinion from other people on A/B comparison).
The chart has the original speaker THD (Blue line) plus 0.05% (RED line) and plus 0.001% (Green line).
0.001% is not even possible to see - it gets perfectly superposed on the original.
Would you pay good money to have the green line instead of the red line?
I'll pay for what sounds better.
But I meant another aspect - why is there a difference in the sound of amplifiers/pre-amps,/DACs/etc., if their THD is 10-100-1000 times lower than that of speakers?
Alex.
But I meant another aspect - why is there a difference in the sound of amplifiers/pre-amps,/DACs/etc., if their THD is 10-100-1000 times lower than that of speakers?
Alex.
Is there a sound difference?
Do you perform statiscal double blind tests when comparing devices?
Two different amps A (THD 0.05%) and B (THD 0.001%) are blindly switched for you 20 times and you don't know which is A or B.
Can you detect 100% of 20 times that B sounds better than A?
Yes.
Many times, and not only me.
I didn't said "better", i said "differently".
If all amplifiers/DAC/etc. sounds the same - what we are doing here?
Alex.
If you have 2 amps that sound different make a recording with an ADC of amp speaker outputs and compare the recordings with DeltaWave. If you hear a difference you most likely will see a difference in DeltaWave. Then you can better analyze why there is a difference.
I didn't mention that all amplifiers/DAC/etc sounds the same. Check my posts.
What I've mentioned, is that when you have an electromechanical device that has THD around 0.5%, it makes no sense to build electronic devices with super low THD such as 0.001%, 0.0001%. If your electronics have, let's say, 1/10th of the THD of the weakest element in the chain, the final result will not be much different when you sum all and I've shown it in the chart. So there is a THD level good enough and below that will not make much difference.
There are bad amplifiers in the market, with slow slew rate, high THD (>0.5%), very noisy etc, and this makes a difference in the sound.
You said something like: "all amplifiers with THD lower than speaker's THD, should sounds the same".
I already agreed above. 🙂
Alex.
Lower enough, such as 1/10th of the weakest element in the chain in my examples, from the point of view of THD only.
There are other parameters to look at, such as frequency response, phase response, S/N etc.
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Of course, but it was meant "all other things being equal".
There is an even more important parameter than THD - IMD.
Alex.
There is an even more important parameter than THD - IMD.
Alex.
Your speaker is not that good compared to this:
https://www.diyaudio.com/community/threads/virtual-audition-of-very-simple-quasi-mosfet-amp.295286/
Yes, this other speaker is better than mine in terms of THD (around avg 0.3% and max 1%)
Mine has THD around avg 0.5% and max 2% to 3.5% on the room peak/null resonances (the measurement was taken indoor).
Since I had this real data on hand, I took it just an example to comment how electromechanical typical THD (>0.1% in general) compares to electronic low typical THD. The discussion focussed on how the small THD electronics influences the final THD sum of whole chain (vinyl, RIAA, amp and speakers) and how low should we push the electronics THD.
Can you hear the sound different of amplifier with THD about 0.1% and 0.001% with same speaker?
If you cannot, any amplifier will suit to your need.
As an engineer, I will compromise the cost and technical aspect. Example, in phono pre-amplifier I will prioritize lower noise rather than lower THD. But if I can achieve all with relative low cost then why not? And if I design for many people, I do not assume other people have same capability of my listening skill. I will assume other people have better listening skill than me. In real life I met a person who have better listening skill than me. He can know the sound different very fast, but I need several times to listen it to know the sound different.
If you cannot, any amplifier will suit to your need.
As an engineer, I will compromise the cost and technical aspect. Example, in phono pre-amplifier I will prioritize lower noise rather than lower THD. But if I can achieve all with relative low cost then why not? And if I design for many people, I do not assume other people have same capability of my listening skill. I will assume other people have better listening skill than me. In real life I met a person who have better listening skill than me. He can know the sound different very fast, but I need several times to listen it to know the sound different.