HEDD Type 20 MK2 Monitor Review

[ctrl]

With the port closed, the Type 20 MK2 brings a delightful experience to the party. Not only is it tonally accurate, it also sounds "pretty" and "hi fi" for lack of a better word. There is extra resolution, detail and openness that I can't explain but enjoyed having.

The version with the closed BR port shows a more balanced frequency response and significantly more low-end bass (that could shift the listening impression with the CB version to favorable):

To better see the differences, here is the diagram normalized to the CB version.
The CB version has less bass boost around 50Hz and significantly more low-end bass below 40Hz***:


*** Keep in mind that in this frequency range temperature differences and noise can have a large influence on the measurement.

 

[unpluggged]

There is fairly little data on the woofer as well

Most probably they use some variants of Eton Symphony II drivers, so we can at least guess their parameters: https://www.eton-gmbh.com/en/home/

 

[Zvu]

Xmax is peak to peak.

 

[tuga]

With respect to distortion, performance is very good at 86 dBSPL but suffers some at 96:

Is it at all possible to look at the Closed Port harmonic distortion measurements for comparison?

 

[F1308]

Thanks for the review.

I nevertheless think hissing should be mentioned when testing studio monitors.

It is so important I cannot understand there is no mention to it.

Hissing frequency and loudness at one meter should be included in the specifications and not doing so refrains me from buying.

Consider the typical "a bit if you place the ear very close" one gets after asking and let it be placed elsewhere...
Distortion ? A bit if you go high on the volume.
Directivity? It depends a bit on where and how you sit.
Detail? It will depend a bit on the composer, the performance and the mixing.

A pity.

 

[Jerico]

Awesome! Been waiting for a Hedd product to get reviewed as I am a owner of the Type 07 MK1. Looks like a solid offering, just wish measurements were taken without the Lineriser/LF ext. voodoo . I understand though that it must be reviewed at its highest spec. Cheers and appreciate all your work!

 

[617]

I'm not trying to be funny, but many are taking Amir's word that these distort from his subjective impressions. I'm not doubting his impressions, but are we all subjectivists now?

If the distortion tests don't seem to show which speakers sound distorted on playback, though look fine on measurements vs those that look iffy on the chart, but sound fine on playback, what are we supposed to be looking for/getting from distortion measurements?

I'd love some guidance on this, as it seems to be considered the 2nd most important measurement on this site for speakers (FR, then distortion, then directivity).

Distortion does not correlate in any meaningful way to sound quality. Harmonic distortion is not a useful metric in audio.

It's easy to measure, but it simply does not mean anything from a perceptual standpoint.

 

[RobL]

(Harmonic) Distortion does not correlate in any meaningful way to sound quality. Harmonic distortion is not a useful metric in audio.

It's easy to measure, but it simply does not mean anything from a perceptual standpoint.

^ I added the above in parenthesis to your quote. I wouldn’t say the same of IMD…much harder to quantify and MUCH more offensive to the ear.

 

[ctrl]

Just as a small note about the comparison of the harmonic distortion of the KH150 and 20mk2.

Please keep in mind that the HD measurements do not refer to a standardized frequency response. The frequency response of two LS can differ significantly in the low frequency, which influences HD FR.

Below 70Hz, the 20mk2 delivers higher sound pressure (up to 5dB@30Hz), which leads to significantly higher HD***:
on-axis FR of KH150 and 20mk2, difference of 20mk2 to normalized KH150

If the frequency response of the 20mk2 were equalized to that of the KH150, in the low frequency range the difference in HD would be smaller.
The KH150 will still show less HD in the low end than the 20mk2, but not to such a dramatic extent.

*** Provided that the measurements have been carried out at comparable temperatures.

 

[Digby]

Distortion does not correlate in any meaningful way to sound quality. Harmonic distortion is not a useful metric in audio.

It's easy to measure, but it simply does not mean anything from a perceptual standpoint.

So what is it we are hearing when we hear 'distortion' then? IMD or what....you can see how someone new to all this would be confused. I know I am, and I'll have you know I'm no longer new, I've been promoted to major contributor recently! Though, I may still try being addicted to fun, learning hmm....not so much.

Also, if it means nothing perceptually, why bother measuring it?

 

[Spocko]

It's a great time to be shopping for professional/active monitors with the variety of selection, budget and brands out there now!

 

[Spocko]

Also, if it means nothing perceptually, why bother measuring it?

BINGO - you've arrived at the heart of where we're at today. Let's say 35% harmonic distortion is audible and it make sense when comparing 35% to 5% distortion, but with any modern premium equipment being sold today, we're talking about distortion far below the audible threshhold. It would be better just to say "less than 0.1% but companies want to show off their engineering accomplishment (aka what you're paying for) by showing that the extra $500 has pushed distortion even farther below audible threshhold by another decimal point or two!

Maybe it's like knowing your 911 can take the 'Ring faster than your friend's M3, but neither of you would ever drive it beyond the suburbs and yet, just knowing...

 

[GWolfman]

I should say the support from the company has been incredible. They reached out to me to offer the speaker for testing -- something that I have yet to see other companies do. And I was give full access to designer and other staff. I couldn't have asked for more.

That’s fantastic! I wish we had this as the norm.

 

[Allank]

It's a great time to be shopping for professional/active monitors with the variety of selection, budget and brands out there now!

Yes..
With the marginal differences here, unless you have a really well designed and treated room, your room will most likely play into the final sound more than the speakers themselves.

 

[amirm]

Is it at all possible to look at the Closed Port harmonic distortion measurements for comparison?

Sure, I added it to the review:

 

[617]

BINGO - you've arrived at the heart of where we're at today. Let's say 35% harmonic distortion is audible and it make sense when comparing 35% to 5% distortion, but with any modern premium equipment being sold today, we're talking about distortion far below the audible threshhold. It would be better just to say "less than 0.1% but companies want to show off their engineering accomplishment (aka what you're paying for) by showing that the extra $500 has pushed distortion even farther below audible threshhold by another decimal point or two!

Maybe it's like knowing your 911 can take the 'Ring faster than your friend's M3, but neither of you would ever drive it beyond the suburbs and yet, just knowing...

Closer to 100% at bass frequencies. It's a totally meaningless metric. Why would it be noticeable? Musical instruments generate even and odd order harmonics anyway, why should we expect a subtle emphasis of a harmonic, which is completely correlated to the signal (loud when signal is loud, quiet when signal is quiet) noticeable?

I don't know anything about the history of HD analyzers but I suspect the metric was originally developed to characterize the behavior of electronics working at RF frequencies. We didn't invent 'harmonic distortion' to describe something we heard. It's not a perceptual metric and, surprise surprise, it doesn't correlate in any meaningful way to perception.

At best it is a diagnostic tool for speaker designers, and it's also one which is relatively easy to manage. Want low HD? Horns, big woofers.

 

[617]

Sure, I added it to the review:

Amirm has anyone asked you to test the linearizer yet? I think we're all curious what it does.

 

[617]

^ I added the above in parenthesis to your quote. I wouldn’t say the same of IMD…much harder to quantify and MUCH more offensive to the ear.

Do you have a link to a study correlating IMD to perception? I'm not aware of one.

 

[ctrl]

So what is it we are hearing when we hear 'distortion' then? IMD or what....you can see how someone new to all this would be confused. I know I am, and I'll have you know I'm no longer new, I've been promoted to major contributor recently! Though, I may still try being addicted to fun, learning hmm....not so much.

First of all, HD measurements are not completely useless, you just have to be careful when interpreting them.

If we focus only on harmonic distortion, then we can give a theoretical lowest listening threshold given by masking.
The masking limits are mean values and can be individual different.

So we are not asking how harmonic distortion affecting the sound (which has not really been clarified), but below which threshold we can exclude that they affect the sound.
Any speaker whose HD is (well) below the masking curve is virtually perfect (in terms of HD) and produces no audible HD.

The following is a hypothetical assessment:

There are many ways in which tones or HD can be masked: The masker can be white noise, music, a wide or narrow band noise or just a single tone (ordered from best to worst masker).

The worst masker is a single tone (or very narrow-band noise). This could be a piano keystroke, for example (this still has harmonics, of course, but this would complicate our theoretical assessment considerably, so we ignore them***).

Here in the example spectrum of a piano keystroke at C6 1kHz (it's Heather Pierson - When You Wish Upon A Star) you can see that it occurs almost as a pure tone (first and second overtones are already heavily damped, about -40dB and -45dB, no other overtones).


So next we consider how much a single tone (our masker) at 1kHz masks the nearby frequencies. It is important to note that masking is dependent on the sound pressure level (the higher the sound pressure level, the better the masking):

Source: Zwicker, Fastl - Psychoacoustics

In our case, the test tones to be masked from the 1kHz piano stroke is the generated HD2 (at 2kHz), HD3 (at 3kHz), ... HD5 (at 5kHz)... by the speaker.

The gray lines show to which limit HD2 is masked at a masker sound pressure level of 80dB (e.g. piano keystroke at 80dB):
up to -37dB attenuation, i.e. about 1.4% HD2

The blue lines show to which limit HD5 is masked at a masker sound pressure level of 80dB:
up to -60dB attenuation, i.e. about 0.1% HD5

This is the reason why it is said as a rule of thumb that the higher the order of the HD, the more problematic they are.


If one now carries out these "considerations" for different frequencies, one obtains the following for the masking limits for HD2 at different sound pressure levels:

This is the reason why it is said that HD is much less audible at low (and very high) frequencies than around 1kHz.
Any loudspeaker whose HD2 remains below these audibility limits is very unlikely to have any audible effect (but see ***). Now repeat this for HD3...HD7...

In case it's not entirely clear what I mean by that, I've babbled about it before:

Post research here that casts doubt on ASR objectivism

In an interview with Earl Geddes, @hardisj uncovered this notable insight on how masking completely renders THD nearly pointless at higher SPLs as high listening volume significantly masks distortion to where it's inaudible (I've linked this specific segment below). This is significant because...

www.audiosciencereview.com

Buchardt S400 Speaker Review

I'm not sure ... but masking thresholds are well-researched and documented in the field of psychoacoustics (which fwiw I am not in). There's not a lot of mystery left. So, the mystery to me is simply that us should rely on a hobbyists attempt to derive the said thresholds from somewhere else...

www.audiosciencereview.com

So we now have a speaker with >5% distortion which isn't audible subjectively. Is a SINAD of 96dB poor?

Might be why tweeters still seem to sound fine even with relatively high levels of 2nd-order distortion, f1+f2 is high enough that we don't care too much and f1-f2 is more or less outside their reproduction range. Agree wholeheartedly with your post, bar this point :p E.g: 2kHz + 3kHz = 5kHz...

www.audiosciencereview.com

*** Since HD2 corresponds to the first overtone, HD3 to the second overtone, and so on, it is clear why these greatly complicate our hypothetical assessment. One might ask at what HD portion "added" to the harmonics a tonal change is perceptible.

 

[Somafunk]

Amirm has anyone asked you to test the linearizer yet? I think we're all curious what it does.

Here’s what Hedd say about the lineariser ,