Dutch & Dutch 8Cs

[graz_lag]

True, but you can do it with a lot less displacement than that. Requires very large woofers though. I'm not sure why you'd want to do it in the first place, anyway, especially in a domestic context where sub-audible frequencies are likely to cause audible rattling. Or any context for that matter...

Hmm ... My REL sub-bass system (10" drive) vibrates much less (or practically doesn't @svart-hvitt) than my Klipsch subwoofer with 12" drive ...

 

[Sal1950]

Either you have a large box with large diameter drivers, or you have a smaller box with smaller drivers with a large linear range of motion.
Displacement is displacement, however it is achieved.

True but you have to factor in efficiency of design. Sealed, ported, horn loaded, tunnel, all introduce a variable.

 

[andreasmaaan]

Hmm ... My REL sub-bass system (10" drive) vibrates much less (or practically doesn't @svart-hvitt) than my Klipsch subwoofer with 12" drive ...

What are the models? I’m sure if you look at all the variables involved and match SPL levels at a given frequency the reasons for this will become apparent.

 

[andreasmaaan]

Either you have a large box with large diameter drivers, or you have a smaller box with smaller drivers with a large linear range of motion.
Displacement is displacement, however it is achieved.

Besides, this clip is just showing off capability. Practicality has little (if anything) to do with the demonstration, IMO.
Just thought it was a visual treat.

I think we were at cross-purposes actually. When it comes to air, displacement is displacement, but not when it comes to voice coil displacement (vs SPL).

And yeh, the video is nice to watch

 

[mitchco]

All that movement with no sound.

If you scroll 3/4 the way down in this article, you can see similar... with sound
https://www.computeraudiophile.com/ca/reviews/dutch-dutch-8c-loudspeaker-review-r739/

 

[Soniclife]

However, assuming you want to reproduce a 15Hz sinewave, better that you do it with a lot of displacement than that you don't do it at all, I guess.

Much better to hear a frequency with distortion that not at all, lots of the time. But what happens when you cannot hear the frequency because it's so low, can we feel distortion?

My guesstimate is that a pair of 8c which have 4 x 8" drivers is similar to 1 x 13.5" driver, so they will be similar to a sealed 13.5" sub for output. Ignoring all the other variables around amp power, drive unit efficiency, box volume etc.

 

[andreasmaaan]

Much better to hear a frequency with distortion that not at all, lots of the time. But what happens when you cannot hear the frequency because it's so low, can we feel distortion?

My guesstimate is that a pair of 8c which have 4 x 8" drivers is similar to 1 x 13.5" driver, so they will be similar to a sealed 13.5" sub for output. Ignoring all the other variables around amp power, drive unit efficiency, box volume etc.

I would have said more like 11" based on surface area, but otherwise agree in principle.

And I'd say you'd feel the 15Hz sinewave and hear the distortion it generates.

 

[Soniclife]

And I'd say you'd feel the 15Hz sinewave and hear the distortion it generates.

Good point. What about a 7hz fundamental with 14hz 2nd order distortion, how would that work?

 

[Purité Audio]

Have you heard the, yet sonic?
Keith

 

[Soniclife]

Have you heard the, yet sonic?
Keith

No, I intend to sometime, as well as the Kii 3, they might be perfect for my room.

 

[andreasmaaan]

Good point. What about a 7hz fundamental with 14hz 2nd order distortion, how would that work?

Then you'd feel the fundamental and 2nd harmonic, and hear (and feel) the 3rd and higher order harmonics, plus all the resultant IM distortion if a complex signal is being reproduced

At some point though I think two realities need to be acknowledged:

• In most rooms, sub-audible frequencies may well cause more harm than good because they will be likely to induce rattling in the furnishings and maybe even the structure
• The stress these frequencies place on woofers, especially if below the resonant frequency (if sealed) or tuning frequency (if ported), will tend to radically interfere with the reproduction of audio frequencies, resulting in lots of unnecessary nonlinearity (especially IMD) in the audio band.

OTOH, most recordings don't contain very much below 25 or 30Hz in the first place anyway.

 

[Soniclife]

I would have said more like 11" based on surface area, but otherwise agree in principle.

There is a lot of guessing here, but this is my maths.

8" = 203.4mm diameter, allow 50mm for bits that don't move = 18482mm2 area, so 4 = 73928mm2
13.5" with the same logic = 67380mm2.

Real measurements will change the numbers, probably a lot.

 

[svart-hvitt]

Then you'd feel the fundamental and 2nd harmonic, and hear (and feel) the 3rd and higher order harmonics, plus all the resultant IM distortion if a complex signal is being reproduced

At some point though I think two realities need to be acknowledged:

• In most rooms, sub-audible frequencies may well cause more harm than good because they will be likely to induce rattling in the furnishings and maybe even the structure
• The stress these frequencies place on woofers, especially if below the resonant frequency (if sealed) or tuning frequency (if ported), will tend to radically interfere with the reproduction of audio frequencies, resulting in lots of unnecessary nonlinearity (especially IMD) in the audio band.

OTOH, most recordings don't contain very much below 25 or 30Hz in the first place anyway.

I think really low frequencies are needed in films where rattling may even be part of the fun.

 

[Soniclife]

Then you'd feel the fundamental and 2nd harmonic, and hear (and feel) the 3rd and higher order harmonics, plus all the resultant IM distortion if a complex signal is being reproduced

At some point though I think two realities need to be acknowledged:

• In most rooms, sub-audible frequencies may well cause more harm than good because they will be likely to induce rattling in the furnishings and maybe even the structure
• The stress these frequencies place on woofers, especially if below the resonant frequency (if sealed) or tuning frequency (if ported), will tend to radically interfere with the reproduction of audio frequencies, resulting in lots of unnecessary nonlinearity (especially IMD) in the audio band.

OTOH, most recordings don't contain very much below 25 or 30Hz in the first place anyway.

I agree on all the sensible reality based stuff.

I'd just never thought about how sensitive we might be to distortion below the hearing threshold, and was interesting in the theoretical idea of it, it intrigued me.

 

[andreasmaaan]

There is a lot of guessing here, but this is my maths.

8" = 203.4mm diameter, allow 50mm for bits that don't move = 18482mm2 area, so 4 = 73928mm2
13.5" with the same logic = 67380mm2.

Real measurements will change the numbers, probably a lot.

Yes @Soniclife, I was just posting to say I'd realised our misunderstanding over this earlier.

To my knowledge, each 8c contains only 2 x 8 bass woofers, so that's where I got my estimate from. And yeh, I wasn't making calculations for effective surface area, which would change things somewhat as you suggest.

 

[andreasmaaan]

I think really low frequencies are needed in films where rattling may even be part of the fun.

Had totally forgotten there was a whole species of human out there interested in stuff other than music

 

[Soniclife]

To my knowledge, each 8c contains only 2 x 8 bass woofers, so that's where I got my estimate from.

I was basing it on a stereo pair, and the understanding that low bass is usually mono on recordings, so they all contribute to output. So as a system they should be very capable, more so than most large three way passive speakers.

 

[andreasmaaan]

I was basing it on a stereo pair, and the understanding that low bass is usually mono on recordings, so they all contribute to output. So as a system they should be very capable, more so than most large three way passive speakers.

Ok fair enough. Based on the surface area or effective surface area, these speakers should be about as capable in the sub-bass range as a pair of stereo speakers with one 10" or 11" woofer per side, all else being equal - which of course it won't be necessarily

 

[Purité Audio]

No, I intend to sometime, as well as the Kii 3, they might be perfect for my room.

They are both really good, and their design makes them very room friendly.
Keith

 

[andrew]

Has anyone tried a single ended (RCA) input (using an adapter) to the 8c? The manual has a recommendation for balanced input but I’m interested in using a reasonably priced AV Pre Pro that just has RCA line level outputs. Thanks in advance