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Harbeth Monitor 30 Speaker Review

amirm

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#1
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):

Harbeth Monitor 30 Speaker Review.jpg

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:

Harbeth Monitor 30 Speaker Back Panel Connectors Review.jpg

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:
Harbeth Monitor 30 Speaker CEA 234 Spinorama Dashboard Audio Measurements.png


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:

Harbeth Monitor 30 Speaker BBC dip 3 kHz balloon plot Audio Measurements.png

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:
Harbeth Monitor 30 Speaker Directivity Audio Measurements.png


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:

Harbeth Monitor 30 Speaker Predictived In Room Response Audio Measurements.png


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:
Harbeth Monitor 30 Speaker Impedance and Phase Audio Measurements.png


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:

Harbeth Monitor 30 Speaker Sensitivity Audio Measurements.png


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:"

Harbeth Monitor 30 Speaker Waterfall Cumulative Spectral Decay CSD Audio Measurements.png


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:

Harbeth Monitor 30 Speaker Step Response Audio Measurements.png


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:
Harbeth Monitor 30 Speaker Horizontal and Vertical Reflections Audio Measurements.png



Harbeth Monitor 30 Speaker Early Reflections Audio Measurements.png


Harbeth Monitor 30 Speaker Full Horizontal and Vertical Reflections Audio Measurements.png


Harbeth Monitor 30 Speaker Horizontal Contour Audio Measurements.png


Harbeth Monitor 30 Speaker Vertical Contour Audio Measurements.png

Full spin data is enclosed.

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



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):

Harbeth Monitor 30 Speaker CEA 234 Spinorama Dashboard Audio Measurements.png


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/
 

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digititus

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#2
I have a set of Compact 7's sat in storage for the last 5 years. Need to dig them out eventually. I did like them with an all vinyl setup
 

amirm

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"good supply of bear"? It's England, not Canada… :)
I used to have an R&D group in UK (in Redding). I would land at 6:00am there all jetlagged. Drag myself to work, have all day meeting than dinner with the team until 9:00 pm where they would down every bottle of wine they could drink. Then on the way back one or two would always ask, "so how about we go to the pub for a few bears now???"
 

Thomas savage

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#7
I used to have an R&D group in UK (in Redding). I would land at 6:00am there all jetlagged. Drag myself to work, have all day meeting than dinner with the team until 9:00 pm where they would down every bottle of wine they could drink. Then on the way back one or two would always ask, "so how about we go to the pub for a few bears now???"
Amirm , Chief party pooper .

Maybe they thought the only way to get through working with you was to ' drink through it ' , iv had many family christmases like that.
 

GaryMnz

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Pretty much what I would expect the Harbeths to measure like. If you've ever sat and listened to them, well set up in a good system, you will know that they are very satisfying. Your measurements, while useful, don't pickup the subtler stuff... Cone materials? How do they change the sound? Etc etc...
 

RayDunzl

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#10
Personal Data Point:

Harbeth was about the only speaker that made me take notice (in a good way) at the Audio show last year, and are on my "try again" list for next month's show*. I didn't even like the Martin Logans as displayed.

The room was crowded, listened off axis for only a (literal) minute, but thought I liked what I thought I heard.

*this was without any conscious preconceived notion about Harbeth's products, basically, had never heard of them at the time. I don't get out much.
 
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direstraitsfan98

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I wish I was local (and still had) my Harbeth 30.2 to have sent you in for measurement back when I had them. Hopefully more Harbeth speakers are sent your way. I never realized that the Stereophile measurements were so lacking. Based on my experience owning Harbeth speakers and comparing the sound to other speakers I have owned, the BBC dip is certainly very audible and it is something that some people may like. I think it makes music easier to listen to, at the expense you have to turn it up a bit louder to hear things better. Combined with the rather low sensitivity, it does mean you have to turn your volume knob up a bit higher then you'd like.

They are also completely incapable speakers of playing at loud SPL's. I found trying to play Rush, or Daft Punk at sustained SPL's of 90dB average with 95dB peaks was making the speaker strain, the bass defintely sounded distorted to my ears. Would be really nice to see THD measurements added to this at some point if you can manage it.
 
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mitchco

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#14
Thanks @amirm Re: "The tweeter is always "faster" so it generates a response first." I am not sure what you are saying there. I presume you mean that the tweeter arrives first because it is closer to the mic than the woofer. i.e. the acoustical centres are offset with the tweeter arriving first then the woofer. This is typical of most systems that are not "time aligned" (and can't be fixed with eq).

Personally, I hated monitors with the BBC dip as mixing in the studio on those, one compensates for the dip in the mix. Then listening on speakers with no BBC dip, would sound like a "drill in your ears" with too much energy in the frequency range our ears are the most sensitive to (which I believe is the raison d'être for the so called BBC dip, but not good for mixing music on...).

As fyi, JA's measures are highly smoothed.
 
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Juhazi

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#15
Thank You Amir!

Just some comments and a question,
- google didn't give reasonable results to standard ITC-2025 - typo or joke?
- CSD looks believable, Harbeths have very thin boxes which resonate
- step response is typical for a well done Linkwitz-Riley 2nd order xo, just a small hickup at 2,7ms
- vertical off-axis is typical for a 2-way crossed high
- Stereophile's response is averaged above 300Hz, nearfield below https://www.stereophile.com/content...-anniversary-edition-loudspeaker-measurements
Fig.3 Harbeth Monitor 30.2, anechoic response on tweeter axis at 50", averaged across 30° horizontal window and corrected for microphone response, with nearfield responses of woofer (blue), port (red), and their complex sum, respectively plotted in the ratios of the square roots of their radiating areas below 300Hz, 600Hz, and 300Hz.

Atkinson uses accelometer taped on the wall of enclosure and he measured these vibrations of Harbeth 30.2

Photo of model 30 without grilles
 
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LTig

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#17
Those results are more or less just what I had expected, and what you get without wave guides or other means to control dispersion.

I had a DIY speaker similar to the LS3/5a (Kef B110A and Audax HD25, later extended to 3-way with a separate Housing with a B139B) for a few years, and they sure were better than the shrill sounding Heco 3-way bookshelfs I had before. They were not built to BBC standards of course, but the falling FR as seen in the plots reminds me how mine did sound.

EDIT: Last year I sold the 2-ways to an audiophile DIYer who needed a pair of B110As to build an LS3/5a. All chassis were still in perfect working order despite being 31 years old!
 

amirm

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Thanks @amirm Re: "The tweeter is always "faster" so it generates a response first." I am not sure what you are saying there.
Tweeter is playing higher frequencies so its rise time is naturally much faster.
 
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