• WANTED: Happy members who like to discuss audio and other topics related to our interest. Desire to learn and share knowledge of science required as is 20 years of participation in forums (not all true). Come here to have fun, be ready to be teased and not take online life too seriously. We now measure and review equipment for free! Click here for details.

layered distortions

Joined
Aug 30, 2018
Messages
51
Likes
105
Location
NorCal
#1
This may have been addressed before but I've been wondering if any tests on chains of equipment have been done before. For example what is the end result if one takes a DAC that tests poorly and connects it to a preamp that tests poorly and then connects it to an amp that also has poor numbers and looks at the end result of the signal? How bad does the final output look in comparison to a chain of equipment that all tests well?
I'll admit I'm a bit of a tube guy but I've always been confused by people that use a DAC with tubes and a preamp with tubes and a tube amp together because it seems like at that point even if you like the sound of tubes the layered on effect would be too much.
 

Cosmik

Major Contributor
Joined
Apr 24, 2016
Messages
2,467
Likes
1,162
Location
UK
#3
This may have been addressed before but I've been wondering if any tests on chains of equipment have been done before. For example what is the end result if one takes a DAC that tests poorly and connects it to a preamp that tests poorly and then connects it to an amp that also has poor numbers and looks at the end result of the signal? How bad does the final output look in comparison to a chain of equipment that all tests well?
I'll admit I'm a bit of a tube guy but I've always been confused by people that use a DAC with tubes and a preamp with tubes and a tube amp together because it seems like at that point even if you like the sound of tubes the layered on effect would be too much.
A bigger question would be: why does anyone bother with equipment that measures poorly, when equipment that measures well is available so cheaply?
 

Blumlein 88

Major Contributor
Joined
Feb 23, 2016
Messages
4,693
Likes
3,117
#4
I've run identical tube amps in series. Loaded the first with power resistors then tapped it to reduce level and feed to the second amp. With music you hardly notice. With test tones it's more obvious.

I've also done DA/AD loops. Distortion is so low there's essentially no difference. Measured distortion works like you'd expect. .1% becomes .2% becomes .3% etc. Noise levels go up 3db per trip through. With dacs being so quiet that isn't a problem until many loops through.

Now tube amps will alter the signal differently than a tube pre amp so that might be more noticeable depending upon the particular unit.
 
Joined
Aug 30, 2018
Messages
51
Likes
105
Location
NorCal
#7
A bigger question would be: why does anyone bother with equipment that measures poorly, when equipment that measures well is available so cheaply?
A lot of people don't realize that there are even sites like this with the measurements listed and a lot of products that test poorly get really stellar reviews. And many just buy what the salesperson says is good.

I guess it would vary from one combination to the next if the spikes overlapped and added to each other which would drive the distortion more into the audible range or were next to each other and just added more overall distortions.
 

DonH56

Major Contributor
Technical Expert
Patreon Donor
Joined
Mar 15, 2016
Messages
2,307
Likes
2,045
Location
Monument, CO
#8
In general it will RSS (root-sum-square -- add up the sum of the squares of the noise/distortion terms, then take the square root) but for harmonic and intermodulation distortion may be closer to additive (phase differences cause amplitudes to vary). Of course you need to account for the gain through the chain. We do this all the time for RF systems; there is a trade among gain, noise, distortion, and power that can get gnarly at the system level with lots of elements cascaded. I used to have a spreadsheet for basic what-if trades but used a simulator and then measured for better accuracy.

FWIW, the rule of thumb is that a source 10 dB lower contributes "negligibly". I have a chart, somewhere, showing the relative contributions to the net output for various distortion/noise levels.
 

Cosmik

Major Contributor
Joined
Apr 24, 2016
Messages
2,467
Likes
1,162
Location
UK
#9

Blumlein 88

Major Contributor
Joined
Feb 23, 2016
Messages
4,693
Likes
3,117
#11
In general it will RSS (root-sum-square -- add up the sum of the squares of the noise/distortion terms, then take the square root) but for harmonic and intermodulation distortion may be closer to additive (phase differences cause amplitudes to vary). Of course you need to account for the gain through the chain. We do this all the time for RF systems; there is a trade among gain, noise, distortion, and power that can get gnarly at the system level with lots of elements cascaded. I used to have a spreadsheet for basic what-if trades but used a simulator and then measured for better accuracy.

FWIW, the rule of thumb is that a source 10 dB lower contributes "negligibly". I have a chart, somewhere, showing the relative contributions to the net output for various distortion/noise levels.
In my example I was doing repetitive loopbacks so each time thru distortion was in the same place and magnitude so it just added up. Which isn't the same situation where different levels of distortion are adding up like adding distortion from a preamp and the following power amp and the following speaker. RMS would likely be that. Yeah I always didn't worry if some source if 15 db lower.
 

gvl

Addicted to Fun and Learning
Joined
Mar 16, 2018
Messages
670
Likes
293
Location
SoCal
#12
Gives them golden ear cred to say it measures poorly, but sounds better. Or if it measures bad and sounds good you are measuring the wrong thing. :cool:
Here's my Khadas board story. Realistically it produces the cleanest sound I heard in my system, the level of details, clarify, and dynamism is mind blowing as it should be considering the measurements. Do I like it? Yes, in a "wow" kind of sense, but I find that this is not what I need to just kick back and enjoy my time with music after I come home from work, the softer R2R DAC I use has a magnitude worse techical performance but does a much better job at that. I'm a technical enough person to make an educated assessment of what things really are, but subjectively this is where I'm at.
 
Last edited:

Blumlein 88

Major Contributor
Joined
Feb 23, 2016
Messages
4,693
Likes
3,117
#13
Here's my Khadas board story. Realistically it produces the cleanest sound I heard in my system, the level of details, clarify, and dynamism is mind blowing as it should be considering the measurements. Do I like it? Yes, in a "wow" kind of sense, but I find that this is not what I need to just kick back and enjoy my time with music after I come home from work, the softer R2R DAC I use has a magnitude worse techical performance but does a much better job at that. I'm a technical enough person to make an educated assessment of what things really are, but subjectively this is where I'm at.
That is perfectly okay. I'm a sucker for push-pull triode amps. I know they aren't accurate, but I find on the great majority of recordings that kind of inaccuracy is a benefit.

On the other hand on recordings I do myself, and which are very lightly processed or not processed at all, it is the straight wire with gain transparency that gives me the best result. Most recordings are effectively garbage unfortunately. Enjoying music is more important than some purity of playback.
 

Cosmik

Major Contributor
Joined
Apr 24, 2016
Messages
2,467
Likes
1,162
Location
UK
#15
I'm a sucker for push-pull triode amps. I know they aren't accurate, but I find on the great majority of recordings that kind of inaccuracy is a benefit.
A shame that the record producers haven't realised they could be improving their recordings so easily.
 

JJB70

Addicted to Fun and Learning
Joined
Aug 17, 2018
Messages
684
Likes
1,043
Location
Milton Keynes, England
#16
Something that I think gets lost sometimes is that it doesn't matter how well hi-fi equipment measures if the quality of recordings is rubbish as no amount of hi-fi brilliance will compensate for a crap recording. All you will get is very accurate and transparent playback of rubbish.
 

Cosmik

Major Contributor
Joined
Apr 24, 2016
Messages
2,467
Likes
1,162
Location
UK
#17
Something that I think gets lost sometimes is that it doesn't matter how well hi-fi equipment measures if the quality of recordings is rubbish as no amount of hi-fi brilliance will compensate for a crap recording. All you will get is very accurate and transparent playback of rubbish.
But there is a fundamental difference between a recording made as a composite of layers, each of which has undergone some distortion, and the application of blanket distortion to the composite recording such as the would-be amateur record-producer-using-archaic-audio-equipment might be able to provide.

In the former case, there may be a delicious delineation between a clear, pure voice, and some grungy processed bass. In the latter, there is just an overall grunginess, intermodulating the voice with the bass to produce offensive mush. (And let's remember what we mean by 'distortion'. Not some sophisticated signal analyser and harmonic synthesiser, but a bent transfer function. Nothing more sophisticated than that).

One thing I have realised since hearing a reasonable system is that many recordings can comprise these contrasting layers and that even though it seems like a grungy recording on the surface, there may be more to it, and a good system can reveal it.
 
Joined
Oct 23, 2018
Messages
52
Likes
81
Location
Bjerringbro, Denmark.
#18
Something that I think gets lost sometimes is that it doesn't matter how well hi-fi equipment measures if the quality of recordings is rubbish as no amount of hi-fi brilliance will compensate for a crap recording. All you will get is very accurate and transparent playback of rubbish.
I remember at one point talking to an 'audiophile' who told me he was getting sick and tired of the hobby. He had come to the state where he would only buy recordings that he believed was made masterfully in a technical sense, but none of the music was something he enjoyed listening to. That was a real eye-opener for me (I was in my late teens/early 20's). Most of the music I listen to is rubbish, but I still like the idea of having a reasonable amount of versatility to my system/setup, and I feel that aming at transparency is the best way to get that.

One thing I have realised since hearing a reasonable system is that many recordings can comprise these contrasting layers and that even though it seems like a grungy recording on the surface, there may be more to it, and a good system can reveal it.
That's why I like both Hi-fi and Metal :D
 

Veri

Addicted to Fun and Learning
Joined
Feb 6, 2018
Messages
924
Likes
722
#19
Here's my Khadas board story. Realistically it produces the cleanest sound I heard in my system, the level of details, clarify, and dynamism is mind blowing as it should be considering the measurements. Do I like it? Yes, in a "wow" kind of sense, but I find that this is not what I need to just kick back and enjoy my time with music after I come home from work, the softer R2R DAC I use has a magnitude worse techical performance but does a much better job at that. I'm a technical enough person to make an educated assessment of what things really are, but subjectively this is where I'm at.
What R2R DAC :) ?
 

JJB70

Addicted to Fun and Learning
Joined
Aug 17, 2018
Messages
684
Likes
1,043
Location
Milton Keynes, England
#20
On recording music, that is another mature discipline, it is an interesting one as it is part art and part science. The technical aspects are about engineering but a good recording engineer also needs musical and artistic sensibilities. Good recordings aren't necessarily technically perfect. A lot of my classical recordings date to the 60's (and many are older). These recordings tend to have audible hiss and some technical imperfections but in many cases the recording engineers achieved outstanding results and the resulting recordings still cut the mustard. Mic placement, venue acoustics, recording levels etc were done extremely well even though the technology was primitive compared to that which is easily accessible to amateurs today. On the other hand I sometimes listen to opera recordings where it is like the orchestra and singers are in different venues and with vocals far too forward. And classical music also has issues with remastered music even if it avoided the excesses of the noise war. When I listen to pop things have really gone backwards, I hoped equalising techniques would end the noise war but as that happened a market transition to BT speakers meant material was still compressed so it could be played loudly on BT speakers, car stereos etc.
That said I do think that a mediocre recording of great music is to be preferred over an audiophile recording of music that does nothing for me.
 
Thread starter Similar threads Forum Replies Date
amirm Audio Reference Library 16

Similar threads

Top Bottom