Confused regarding Harbeth speakers and sensitivity

[Puma Cat]

Originally Posted by BuffaloBill

You and I can respectfully agree to disagree.

Yep, and that's fine.

Cheers.

[BuffaloBill]

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.

[Puma Cat]

Originally Posted by BuffaloBill

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.



A 3-dimensional, surface response plot the impact of Sub crossover and gain on a 155 Hz peak mode.


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.

[Tie_breaker]

Originally Posted by Puma Cat

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

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.

[Puma Cat]

Originally Posted by Tie_breaker

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.

[W9TR]

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

[Puma Cat]

Originally Posted by W9TR

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.

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

[GeAllan70]

Originally Posted by Puma Cat

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

Cheers,
Stephen

^^^

+1

[W9TR]

Originally Posted by Puma Cat

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

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

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.

[Puma Cat]

Originally Posted by W9TR

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.