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Harbeth Monitor 30 Speaker Review

AudioTodd

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This is a review and detailed measurements of the Harbeth Monitor 30 25th anniversary speaker. It is on kind loan from a local member. This specific speaker came out around 2002 I think and cost US $3,200 around that time. Being patterned after the famous BBC LS 5/9 speakers, I imagine the design is still the same to this day. The latest model seems to go by 30.1 designation.

The Harbeth logo was in danger of coming off so the owner pulled it off. Here is what it looks like (I know, very bland):


It barely fit in my little photo booth so not very large. The grill is tricky to remove so I did not attempt to do so. I am told the recommendation is to use it with the grill so that is how I measured it.

The back panel shows ability for bi-wiring:


Love the bit about the speaker being in their log book. Well, its measurements are now in our log book as well. :)

Let's get into measurements. Since this is a passive monitor, I followed the CEA 2034 recommendation of feeding it 2.83 volts. Temperature was a balmy 57 degrees. Altitude was 13 feet above sea level. Acoustic center of the speaker was determined following ITC-2025 Part B standard (I used my Mitutoyo micrometer). Any wind in the lab was self-generated due to previous meal.

CEA-2034 Spinorama Measurements
As usual we start with our master dashboard of the speaker which is its "spin" data:
View attachment 47514

I have gotten requests for "clean" versions of this picture so I have avoided making notations on it. Let me know if that is a good or bad idea.

There is a lot of controversy around the so called "BBC dip" where around the crossover frequency the on-axis response drops fair bit. Tom Holman of the T in THX recommended that the same dip be implemented in Audessey Room EQ! A mistake in my opinion. Anyway, we see the dip starting around 3 kHz. Getting a 3-D plot of that region gives us this complex sound intensity:


I don't think this is what you want in a speaker. Put another way, it is the classic engineering work of calling a defect a feature. :) We can see the havoc it plays on our early window (and sound power) directivity:
View attachment 47516

Why would I want to have a suck out in that region of audible spectrum? I let you google forever to read the fights back and forth.

Taking into account the direct and early window reflections to predict the in-room response, we get:

View attachment 47517

The dip is there of course around the crossover frequency. And general unevenness. The overall tilt is quite exaggerated so perhaps good for people with high sensitivity to high frequencies, it would tame the harshness in that region in the recording.

Basic Speaker Measurements
Let's start with impedance and phase measurements:
View attachment 47519

Specification is 6 ohms. Standard requires staying about 80% (?) of this value which would be 4.8 ohm. If you cheat a bit it gets there. Worst case phase is around 100 Hz which impedance around 9 ohms. This make the effect load to be much lower (i.e. the difficulty that the amplifier sees).

Sensitivity ("efficiency") is almost always given as a single number by the manufacturer but it varies based on frequency:

View attachment 47520

In most of the frequency range the actual sensitivity is better than specified 85 dB which is good.

You all seem to like colorful 3-D graphs so here is the so called "waterfall:"

View attachment 47521

I don't trust this graph much. For one thing, these graphs can be manipulated to show any and all things. More importantly though, the Klippel NFS system I use is great for measuring frequency response but on tests like this, its structure can resonate with the speaker, which would show up as its own slices above. Maybe after I test more speakers I get confidence on reliability of this (rather useless) measurement.

Finally, step function seems to be a popular item so here it is, zoomed properly now to show the step response of each driver:

View attachment 47522

The tweeter is always "faster" so it generates a response first. It is swinging negative which means it is out of phase with the woofer which takes its time to generate its response to the right of it at opposite phase. There is discontinuity between the two (around 2.8 milliseconds).

Advanced Speaker Measurements
Here is the rest of the bits for those interested:
View attachment 47524


View attachment 47525

View attachment 47526

Full spin data is enclosed.

Correlation With Other Measurements
Stereophile measured a much more recent version and reported this for frequency response:

318harbeth.H302fig3.jpg


Focus on the black line only. It looks a heck of a lot better than our graph. Almost flat and smooth on Axis! Well, that is not what is really going on.

First the easy part, it has the same bass hump as we do (although their measurements usually exaggerates this due to their close-in measurement technique):

View attachment 47514

We show a dip post our peak in low frequency but they don't. The reason is that they are using gated measurements to eliminate echos and that hugely reduces resolution in a few hundred hertz (to one or two data points). Past that, they do have the dip but they show such a low resolution compressed graph that it is not nearly as visible. We both show the couple of peaks close to 10 kHz.

Overall, given the radically different measurement setups, I say the correlation is very good. Our data is much higher resolution than theirs.

Listening Tests
No time or setup yet for listening tests. Will do some and report back later.

Conclusions
It is interesting to measure these "classic" speakers to finally put some hard data behind their objective performance. As expected the halo is more positive than the objective data indicates. The cost of these speakers is way up there. I appreciate being built in England and needing to have good supply of bear for works after hours but it is a lot of money for this kind of measured performance.


------------
As always, questions, comments, recommendations, etc. are welcome.

Had some great sushi at my favorite spot when I went to pick this and other speakers. It was over US $60 for lunch! While I feel satisfied, I also feel poor. So please help lift my spirits by donating using: https://www.audiosciencereview.com/forum/index.php?threads/how-to-support-audio-science-review.8150/
Thanks for the wind joke - your best I’ve seen - BUT my sense of humor has been said to have stopped developing in middle school...
 

Blake Klondike

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So excited to see these measured! It makes total sense to me, as a layman, that digital gear measurements show exactly what the device is outputting, and therefore what it objectively sounds like. Total beginner speaker question: Are there audible qualities these speakers might have that the measurements can't reflect? Am I correct that these charts show how much/what type of coloration the speakers apply vs. "flat" reproduction?
 

617

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@amirm what the heck is going on with the impedance plot? Specifically showing the bass resonance region? Never seen an impedance sweep that ragged.
 

Koeitje

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I kinda dig the retro look, but not the retro performance :D. Hard to find a high performance loudspeaker with a nice classical look (just a wooden box with high quality wood finish).
 

napilopez

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Thanks Amir! Loved this review.

A few thoughts:
  • I like seeing the "clean" spinorama, and you can always repost the image with comments. Alternatively, you can make your comments on the spin and attach a "clean" spin to the post at the bottom.
  • Seems to me basically like a decent speaker with too much of a tilt and that's quite expensive. Tone controls to the rescue! Can't fix the directivity issues but it's not a terrible PIR I think.
  • The different scaling within and throughout reviews is throwing me off, especially when comparing between reviews. For example, the estimated in room response is in a 30dB scale vs 50dB in others, so the tilt looks worse than it is - although still too much.
  • The Stereophile measurements and gated measurements in general should have enough resolution at around 3KHz. Any differences are likely due to the difference speaker models and the fact that Stereophile's listening window doesn't include vertical data. I believe JA uses a 5 Ms window, which gives a resolution of 200Hz. So roughly 15 data points around 3Khz. The klippel uses windows measurements in the higher frequency range no?
  • The 3D balloon, once again, is awesome.
 
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amirm

amirm

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Are there audible qualities these speakers might have that the measurements can't reflect?
Certainly power capabilities. You can cause severe distortion in speakers when you exceed how much power they can generate. Distortion is another factor but I don't yet have confidence in the measurements to publish them.
 
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amirm

amirm

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@amirm what the heck is going on with the impedance plot? Specifically showing the bass resonance region? Never seen an impedance sweep that ragged.
It is a very high resolution sweep (0.73 Hz). The typical published ones are likely at much lower resolution. Do you want me to go in that direction?
 

Absolute

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This is just pure porn! I'm loving these speaker measurements, it'll be a new dawn for many things. Quality of speakers first and foremost I hope.
That said, I'd imagine this speaker to sound very comfortable and nice for whatever that's worth.
 

phoenixdogfan

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I'm quite certain many consumers prefer that infamous dip. Not accurate, of course, but when speaker designers first implemented it, consumers had limited availability to sophisticated eq systems to filter shoddy recordings (which is to say most recordings), so the "BBC dip" became a thing. Now it's a thing whose usefulness is at an end since consumers who can roll their own digital eq's for their harsher sounding recordings if they so choose.
 

Soniclife

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Is this model new enough to have their newest cone material? I've forgotten the name they use for it. I'm sure the crossover has been improved in newer versions as well, but how much I've no idea.
 

Absolute

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I'm quite certain many consumers prefer that infamous dip. Not accurate, of course, but when speaker designers first implemented it, consumers had limited availability to sophisticated eq systems to filter shoddy recordings (which is to say most recordings), so the "BBC dip" became a thing. Now it's a thing whose usefulness is at an end since consumers who can roll their own digital eq's for their harsher sounding recordings if they so choose.
Yes, even the fantastic Devialet Phantom Gold has the same dip;

phantom gold.gif



https://www.soundstagenetwork.com/i...&catid=77:loudspeaker-measurements&Itemid=153

To my ears it pulls back the soundstage too much, but it's certainly forgiving for most music.
 

LTig

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@amirm what the heck is going on with the impedance plot? Specifically showing the bass resonance region? Never seen an impedance sweep that ragged.

It is a very high resolution sweep (0.73 Hz). The typical published ones are likely at much lower resolution. Do you want me to go in that direction?
No, always measure as precise as your tools allow.

There are two small sidebands left (~83 Hz) and right (~88 Hz) of the resonance peak (80 Hz) of the woofer. Just guessing what could be the cause:
  • It's a sealed bass reflex enclosure. Leakage? Some port related resoncance?
  • Resonances of the enclosure? JA's impedance plots also show irregularities which often correspond to resonances of the enclosure.
  • Resonances of the stand or the Klippel structure?
How much voltage do you use to measure the impedance? How long does the sweep take (if it is a sweep at all)?

EDIT: just saw that the enclosure is not sealed - fixed the first bullet point.
 

napilopez

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@amirm Actually soundstage network measured the older versions of the speaker too. Very close correlation in the listening window :) (soundstage does 15 degree horizontal and vertical, as opposed to 30 degrees horizontal and 10 degrees vertical in the spin). I think it's more likely that Harbeth retuned the speaker for its newer model, but we can't know for sure without two measurements from the same source.

https://www.soundstagenetwork.com/measurements/speakers/harbeth_30_domestic/

1580078279919.png


Overlayed:
1580078493390.png


Pretty close considering the difference in listening window technique etc.
 
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