Confused regarding Harbeth speakers and sensitivity
 

Are Harbeth speakers difficult to drive, or not? For example, the Harbeth Super HL 5+ 40th Anniversary Model speakers are rated at 86 dB for sensitivity. However, they're also rated at 6 ohms and not the usual 8 ohms. Are they considered an inefficient speaker or difficult to drive? Is there more to it than dBs/sensitivity?

I used to own the Harbeth SHL 5 35th Anniversary edition. They were paired with a Pass XA 30.8. My 30 watt Pass amp had no difficulty at all with the Harbeth’s. The speakers were a fairly easy load for my amp.

MC252 off the 8ohm taps into my C-7es3's.... Effortless... :thumbsup:

:yes:

Every 3db increase in SPL requires a doubling of power. Combine that with a mid-bass driver with a wide frequency range and that spells potential problems with modulation distortion.

Respectfully, Bill, that doesn't apply with respect to Harbeths. The Radial mid-bass drivers are made from a unique material that is proprietary within the industry and has been in rigorous R&D development for over 40 years by Alan Shaw with respect to to producing superb audio characteristics with very, very low distortion (and that ameliorates this distortion mode).

So, with Harbeths, don't let "specs" mislead you. They are very easy to drive....just ask the dealers that sell them with a very wide variety of amplification compenents, from "mid-fi" to high-end.

I've seen Harbeth C7s driven beautifully with an 8-watt Viva SET as well as mid-power and high-power tube and solid-state amps. Harbeth speakers are probably the most amplifier-agnostic I can think of.

Link to a video of C7s being driven by an 8-watt SET:
https://youtu.be/MytKtPXsfLQ

I drive my 30.2s to levels that will drive folks from the room with an 70 Wpc tube amp. Absoslutely no worries. And they sound amazing and the mid-range is absolutely gorgeous.

Bottom-line: Get the amp you want, get your Harbeths, sit back and enjoy some really beautiful music.

Job done.

Yup...that's 'Beths for you.

Yeah, they're a piece of cake to drive. I'd love to hear mine with a low-power SET or a Pass XA25.

Also, the listening space is important. Smaller speakers in larger rooms will often struggle, regardless of power fed them.

No, they are easy to drive. No worries.

Yes. The Harbeth line of speakers have been in continual research and development for over 40 years by Alan Shaw, regarded as one of the best loudspeaker designers in the world. I would put Alan on the same level as Andrew Jones.

Harbeth don't excel in all areas of high-fi loudspeaker tech specs and "audiophile-geekery" based numbers, nor do they need to be made from X-material, concrete, or aluminum. They are manufactured and voiced like a fine classical music instrument, think of a Guarnerius violin. Each pair is also individually voiced by and matched by hand. Harbeth keeps meticulous records on each pair, and if they ever need to be repaired or refurbished, they can be return to their original specification of performance.

But...they play music better than most any other speaker I can think of.

So...just get 'em, pair 'em with your favorite amp, and call it a day. Sit back and bask in beautiful, natural, and engaging music.

You'll be able to live with these speakers for the rest of your life.

You and I can respectfully agree to disagree.

Yep, and that's fine. :thumbsup:

Cheers.

A low sensitivity speaker comprised of a relatively small mid-bass driver in a small cabinet is not going to overcome the laws of physics. Even if Harbeth uses Houdini cloth for their diaphragm material when the same driver tries to reproduce a 45Hz and 1.5kHz signal at the same time there is going to be problems with transient response, frequency and amplitude modulation distortion, and thermal compression, especially if you want to listen to music at realistic sound levels.

It's not a matter of physics so much that it's a matter of engineering. And, from a sytems engineering perspective, its a potentially a situation of conflicting and possibly interacting set of input, control, and noise factors that drive the functional reponse(s).

And, conflicting functional response(s) can frequently be attenuated, mitigated, and occasionally, not only removed, but improved upon.

The conceptual understanding of this forms the basis of TRIZ (Teoriya Resheniya Izobretatelskikh Zadatch) developed by Altschuler.

The problem many engineers face is they try to solve functional conflicts with a One-Factor-At-A-Time approach and never understand the nature, degree and direction of confllicting interactions between factors. Moreover, they don't develop an understanding of the degree of leverage the factors exert, their direction, the possible interactions, and the degree of statistical impact these factors have on the functional responses, including surface responses.

There well-established ways to get around this, however.

Once the key foundations for this is that the functional responses are identified and can measured with qualified and statistically robust measurement systems (based on MSA). Furthermore, the impact, direction, degree and any interactions between these factors can be characterized with statistically robust analysis platforms, e.g. DOE (Design of Experiments).

Many times functional response conflicts can be attenuated, mitigated, resolved, and in some cases, the functional response(s) can actually improved upon.

By way of example, a DOE I performed to optimize the integration of my REL sub into my 2-channel system to mitigate nulls and peak room modes in my listening room.

http://photos.imageevent.com/puma_ca...Grab%20cap.jpg

A 3-dimensional, surface response plot the impact of Sub crossover and gain on a 155 Hz peak mode.
http://photos.imageevent.com/puma_ca...ponse%20II.jpg

So, while I agree the "physics" will always play a role, I don't believe for a moment that there is no possibility for the potential for functional response conflicts to be attenuated, mitigated, resolved, or improved upon.

Cheers.

I currently have a Line Magnetic 845 Premium integrated SET amp. It's 2x30w and works very well with either 30.2 or SHL5 plus. Sweet sound, especially the mids. I don't feel the need to turn my volume above 11 o'clock. My music preferences are jazz, vocals, instrumental, and classical. My room size is 18x12.

I would LOVE to have a Line Magnetic 845 for my Harbeths. Those sound wonderful. :thumbsup:

Confused regarding Harbeth speakers and sensitivity
 

Bill is referring to Doppler distortion.

If you have a loudspeaker driver reproducing a high frequency tone at the same time as the cone is moving in and out to accommodate a low frequency tone, the pitch of the high tone increases as the cone moves toward the listener with the bass note, and then falls as the cone moves away from the listener.

The level of modulation of the high frequency tone is proportional to the excursion of the cone as it reproduces the low frequency tone.

This generates a form of intermodulation distortion where the high frequency tone is modulated by the low frequency tone.

The result is a set of sidebands around the high frequency tone displaced by +/- the frequency of the low tone.

Loudspeakers drivers with smaller cones are more impacted as they need larger excursions to produce the same audio output as a larger loudspeaker driver. Doppler distortion is proportional to the square of the decrease in cone diameter.

Tom

Thank you, Tom. This was very helpful and informative. :thumbsup:

In the case of the SHL 5+, as this is a 3-way speaker with a dedicated midrange driver and a separate woofer, wouldn't the Doppler distortion be less of a problem or moot?

Cheers,
Stephen

^^^

+1

:thumbsup:

Yes. The issue is ameliorated by limiting the frequency range the midrange driver needs to cover. Having a separate woofer and dropping the tweeter-midrange crossover frequency all help.

Cool, thank you very much, Tom.

Cheers and Happy New Year.

Lower, yes, but you still have a problem with low sensitivity speakers. They require much more power to produce a desired SPL which results in more excursion and therefore more distortion. What Paul W Klipsch described as the "mud factor".

:laughin:

Audiofound, I’m curious of what amp are you planning on using with the Harbeth ?
I’m going to try to keep it simple, we all have an understanding of what a speaker sensitivity means, so I think it comes down on what you wish to achieve. If you listen at high levels then you may want more power/current with a low sensitivity speaker. If not then it’s not necessary. My Harbeth do not play as loud as my 91db speakers but they sound so much better. Don’t get me wrong I enjoy pushing components just to see what “it’s got to give” but just for occasional fun not the norm. One thing I’m convinced of is that they are very good sounding speakers and it would be worth finding an amp that gives you the results you’ll be happy with.

I have a Pass int 250 on order along with an MSB Discrete DAC with additional power supply, and a Roon Nucleus. Just for the record, I have Harbeth Super HL 5+ 40th Anniversary Model speakers at home waiting for the amp.

That is going to sound...wonderful. Very nice system.

Congrats and please post your impressions when you get your Pass Int 250.

Cheers and happy new year.

Wow..! Congrats, I believe you have put together a very nice system, great way to start a year. Like PumaCat says let us know how you’re system sounds, I’m also curious...
Happy New Years everyone...

Thanks guys for the kind, encouraging words. This coming Thursday I’ll make it official. I pay for the system and get it on it’s way to me. I’ll definitely let you know what I think of it. I’m pumped!

Congrats on what will most certainly be an amazingly great sounding system!

We're all excited for you, too! :thumbsup:

Since I've had my Harbeths 40th Anniv. 30.2s since July, I spend more and more evenings where I can't tear myself away from the stereo.

Most importantly, I'm spending that time immersed and engaged in listening to music, and not focusing on audio equipment.

Very cool, that’s a great system you’re putting together.

.

I have Harbeth 30.2 with Accuphase e650. The 30 watt with Harbeth more than enough!
Before this I had nuvista 600 with focal Sopra 2 more watts with higher efficiency speakers I could not reach same spl level as with Harbeth. Don’t know why, can’t be bothered neither. But the 30 watt class a is more than enough for my ears! Very happy music lover again!

Agreed regarding your statement the 40s. More power certainly helped in my case.

Audiofound, what are your impressions on your system? You didn’t come back with an update. If your like me you may still be moving your speakers around unless you dialed them in already. Honestly it took me a a couple of months. Hope your enjoying it...

Sorry for reviving an old post, but the SHL5+ does not have a dedicated midrange or separate woofer. It has a super tweeter, tweeter, and 8 inch mid/woofer that handles both midrange and bass. Am I missing something?

-Scott

Stephen, you make some excellent points. Obviously, the Harbeths aren't going to do 20 Hz notes and will have some dynamic limitations. But your observation that they are tuned like a fine musical instrument as opposed to wringing out every bit of resonance is valid. It's a different and cost effective approach. I'm sure your system sounds amazing.:yes:

Best

Charles