HEDD Type 20 - studio monitor

[Zvu]

Here are some measurements of it:



Source:

It would be good to see how would it look in Amir's setup. Preferably with and without HEDD Lineariser.

 

[Purité Audio]

Here’s a photograph this pair currently in eldest son’s bedroom , haven’t measured them but they sound pretty decent in their ‘stuffed where they will fit’ placement.


Keith

 

[tomtoo]

If i would have the money i would sleep with them. I love them.

 

[Purité Audio]

Is it the soft rubbery coating?
Keith

 

[Zvu]

Is it the soft rubbery coating?
Keith

Few days ago, while browsing through your website, i've noticed that on Hedd Tower Mains page there is a link to D&D. I guess that shouldn't be there.

 

[Purité Audio]

I will amend, thanks.
Keith

 

[tomtoo]

Is it the soft rubbery coating?
Keith

You shouldnt tell me this.

 

[AnalogSteph]

Reading soft rubbery coating is giving me nightmares of sticky Thinkpads, Dell palmrests and Eton radios. Some 2000s car dashboards had issues as well. "Soft touch" plastics were the new hot thing in Chinese manufacturing in the 2000s, but by the looks of it they are easy to get wrong, making them start to disintegrated after a short amount of time. I'd guess that this is not the same stuff though.

 

[Blumlein 88]

Nextel coating. I rather liked it until it turns sticky.

 

[AnalogSteph]

Nextel coating. I rather liked it until it turns sticky.

Big issue for '70s Revox components. AFAIK, they later switched to a different process that no longer exhibited this problem (1K vs. 2K or something?).

 

[Zvu]

I presume that after all this time that rubbery stuff degradation prolem has been solved and new stuff covered with that thing is solid. I've seen it in cars as well. I'm guessing that if it holds up in that conditions, it will be good enough at home exposed to much less UV radiation and temperature swings.

If we put the looks to side (looks great in my book but that is individual), what i like about this little fella are its characteristics. It is very compact for a three way - front is big enough to mount the drivers and port and that's it. It has a front mounted port, it is a fully active analog three way with possibility to use Lineariser plug in (that corrects the phase and frequency response to dead flat). So, actually good for analog zealots/vinyl guys and for the ones that are more open to digital processing that will squeeze a bit more performance out of it that way. It comes with perks of classic studio monitor gear (bass, highs settings). It's electronics is separated in its own chamber and i really like to see that and while it is a bit deeper because of it, front port allows mounting close to front wall. Price of 3000 euros/pair (regular price is around 3300 euros/pair) is not low but might actually be good if it measures properly.

 

[q3cpma]

I presume that after all this time that rubbery stuff degradation prolem has been solved and new stuff covered with that thing is solid. I've seen it in cars as well. I'm guessing that if it holds up in that conditions, it will be good enough at home exposed to much less UV radiation and temperature swings.

If we put the looks to side (looks is great in my book but that is individual), what i like about this little fella are its characteristics. It is very compact for a three way - front is big enough to mount the drivers and port and that's it. It has a front mounted port, it is a fully active analog three way with possibility to use Lineariser plug in (than corrects the phase and frequency response to dead flat). So, actually good for analog zealots/vinyl guys and for the ones that are more open to digital processing that will squeeze a bit more performance out of it that way. It comes with perks of classic studio monitor gear (bass, highs settings). It's electronics is separated in its own chamber and i really like to see that and while it is a bit deeper because of it, front port allows mounting close to front wall. Price of 3000 euros/pair (regular price is arround 3300 euros/pair) is not low but might actually be good if it measures properly.

Sadly, it stands no chance against the KH310A if the linearizer plugin isn't available, like on POSIX platforms. Even with the plugin, I'd probably still choose the Neumann if only for its publicly available and exhaustive measurements.

 

[ctrl]

Its big brother, the Hedd Type 30, was tested in Sound&Recording 02-2017.
An excerpt from the test report was shown by @pozz here in the forum.

The sound pressure ripple was 5.3dB and the maximum pair deviation 1.6dB, both measured in the frequency range 0.1-10 kHz. The maximum pair deviation is somewhat high (<1dB would be good) for the price segment of the studio monitor.

The measurements should apply similarly to the Type 20 model - However, the horizontal directivity of the Type 20 model will of course no longer be symmetrical.

 

[Zvu]

Sadly, it stands no chance against the KH310A if the linearizer plugin isn't available, like on POSIX platforms. Even with the plugin, I'd probably still choose the Neumann if only for its publicly available and exhaustive measurements.

There is obvious directivity error in KH310 which is mainly due to type of midrange and crossover point both upper and lower. I don't like AD conversion for analog input. Unlike KH310, Type 20 midrange works with 7" woofer with much lower crossover point (250Hz), and with very stiff cone material that has good internal damping. That means that breakup will be high and visible in raw measurements but unlike metal cones it will be lower in level and with less after ringing. HEDD 4" composite cone midrange uses steep filter with tweeter and less steep with woofer. 7" woofer and 4" midrange in HEDD look very good regarding cone surface area relation and crossover point. KH310 has 8.25" woofer with 3" soft dome midrange with high crossover point (650Hz) but no waveguide for midrange so it spells disaster in horizontal directivity. Even 4th order slopes didn't help much. KH420 is much better executed but at a price, of course.

So, that's precisely why i'd like to see detailed measurements of Type 20 with Lineariser because i think there is a good chance it is better executed than KH310. KH310 can play much louder, i'll give it that.

 

[Frank Dernie]

Nextel coating. I rather liked it until it turns sticky.

Most of the interior of my oldish car has gone sticky. I got the doorhandles stripped and repainted, doing everything properly would cost thousands.
I have other things which went sticky never again

 

[ctrl]

There is obvious directivity error in KH310 which is mainly due to type of midrange and crossover point both upper and lower.

Yep, due to the chassis arrangement and the high crossover frequency, the KH310 is at a disadvantage in horizontal radiation in the range 400-1000Hz, compared to the Hepp Type 20/30, but between 400-700Hz the Hepp Type 30 also shows abnormalities (and therefore most likely also the Type 20).

KH310 has 8.25" woofer with 3" soft dome midrange with high crossover point (650Hz) but no waveguide for midrange so it spells disaster in horizontal directivity. Even 4th order slopes didn't help much.

The midrange driver of the KH310 also has a small waveguide, which is not helpful in the transition to the woofer, but is helpful in the transition to the tweeter.

When looking at the horizontal radiation as a whole, the KH310 shows a much more uniform radiation compared to the Hepp Type 30 (and thus very probably also in comparison to Type 20).

In addition, there are great differences in the consistency of the series.
KH310: The sound pressure ripple was 2.2dB and the maximum pair deviation 0.45dB, both measured in the frequency range 0.1-10 kHz.
Type 20 30: The sound pressure ripple was 5.3dB and the maximum pair deviation 1.6dB, both measured in the frequency range 0.1-10 kHz.
As already mentioned, in terms of quality, I do not like the pair deviation of the two tested Hepp Type 30 speakers with a maximum of 1.6dB in this price category of studio monitors.


If you look at the measurement of the horizontal FR with deg 0, 15, 30, 45 of the Hepp Type 20 shown by you, you can already see the significant widening of the radiation in the range of 2-4kHz.
This discontinuity in the horizontal radiation could be even more pronounced than with the Hepp Type 30 (shown above).

The extremely sounding tuning (with an extremely wide 6-7dB dip in the range 0.1-10Khz) of the speaker may sound pleasant (if the measurements shown are reliable), but certainly have no place in an audio studio.

 

[Zvu]

I tend to agree with you @ctrl but there are few things i'd like to add.

1. S&R dispersion measurements are normalised to on axis frequency response, not on LW. Since Type 20 is made to compensate for diffraction products on axis, of course it looks worse.
2. Measurements in S&R are done without Lineariser so i think there is no point talking about frequency response ripple untill we see what is it capable of at its best.

Although Herr Klaus Heinz claims that Lineariser works mainly as a phase corrector, there is (in my opinion significant) influence on frequency response curve. It can be seen here.

Type 20 without Lineariser


Type 20 with Lineariser


And at the end there is even a hint of correction for Type 30, with Lineariser:


Source:

Grid is the same but measurements differ quite a bit, in my opinion. Those measurements in first post are more of a teaser for me than something i could rely upon. That off axis measurements posted looks to me like it is done on the woofer side and that dip is a product of diffraction that will not exist when measuring to the other (empty/non woofer) side. When that is put into the equation of measuring it without Lineariser and S&R normalising horizontal dispersion plot based on onaxis response - well, i'm really craving for more detailed measurements now since the concept of a such a compact loudspeaker with that drivers and crossover frequencies looks bulletproof to me.

 

[ctrl]

1. S&R dispersion measurements are normalised to on axis frequency response, not on LW. Since Type 20 is made to compensate for diffraction, of course it looks worse.

The normalized spectrogram gives information about how good the directivity of a loudspeaker is. This directivity can no longer be changed by any "normal" measure. To change it, the crossover or the cabinet would have to be changed.

Therefore, the normalized spectrogram gives information about how much effort has been put into the design, selection of the drivers, design of the waveguide/horn (if available) and the tuning of a loudspeaker.

Here is an example of a loudspeaker with bad horizontal directivity (I'm ashamed of it) and how this bad directivity has to be compensated during crossover and tuning of the speaker to not sound like sh..t.


If you do everything right and, for example, compensate the strong expansion of the radiation in the range of 1.5-4kHz by lowering the on-axis FR (create an wide dip between 1.5-4kHz), you will get a loudspeaker that, all in all (non-normalized spectrogram), radiates quite balanced.



So if you write Hepp Type 20 "compensate for diffraction" this is just a desperate attempt to compensate for a non-optimal radiation by adjusting the on-axis FR.
Don't get me wrong, this can still sound great in a normal listening room, but as a working tool in an audio studio you would want something more neutral.

Compared to the KH310 I would expect that the LW is more balanced there than with the Hepp Type 20, because for example the vertical radiation of the KH310 should be more linear at the transition from midrange to tweeter.
Maybe Amir will get both speakers to measure, then we will have certainty.

2. Measurements in S&R are done without Lineariser.

As written above, it is not possible to correct the errors in the radiation, they can only be compensated by changing the on-axis FR.

When the "Lineariser" linearizes the frequency response on axis, it gets exactly the radiation that the normalized spectrogram shows.

 

[Zvu]

Very nice example and exactly what i was aiming at. I really like your compensated (second) hd graph.

EDIT: i don't see that narrow/wide aberation in KH310A from 500 to 2000Hz as neutral so i couldn't actually say which would sound more natural/neutral. Ideally, both would have flawless horizontal directivity but they don't. One that is obviously better is KH420 but i already mentioned that.

 

[Zvu]

I like comparisons and subjective impressions of this guy: