Dutch & Dutch 8c Review

[Martijn Mensink]

I think it has poor distortion for the price.

As others have noted, the 8c uses a cardioid midrange. The 8" driver is a high-performance midwoofer operating from 100 Hz to 1250 Hz. At the low end of that range, it has to work harder than it would in a sealed box because of the nature of a cardioid system, which relies on a front source and a rear source to cancel rearward energy, the latter of which is inverted and delayed. That the out-of-phase rear-wave cancels rear output, but it also slightly reduces forward output, meaning more excursion is required for the same SPL. This explains the increase in distortion just above the crossover when you really crank them. That said, it’s a very robust driver with excellent power handling, as shown by its low power compression even at much higher levels (see Erin's and SoundStage's measurements). As others have pointed out, this distortion isn't audible at typical listening levels. You'd have to push them quite far before it becomes noticeable.

In the deep bass, distortion is actually very low, especially when you consider the size of the speaker and the fact that it uses "only" two 8" subwoofers. These are OEM variants of the Wavecor SW223, which are actually of very quality. Published distortion figures of the 8c come from free-field measurements, where the woofers work about 6 dB harder than they would in a typical rooms. When placed near the front wall, as intended, the 8c benefits from Boundary Coupled Bass, which significantly eases the load on the woofers. The 8c also extends very low in frequency, so the drivers need to move more air at the lowest octaves, which naturally increases distortion. Some manufacturers reduce bass output at higher playback levels to keep distortion in check. While that approach can be effective, it also alters the tonality. We chose not to go that route. What goes in is what comes out, with no surprises.

 

[dfuller]

As others have noted, the 8c uses a cardioid midrange. The 8" driver is a high-performance midwoofer operating from 100 Hz to 1250 Hz. At the low end of that range, it has to work harder than it would in a sealed box because of the nature of a cardioid system, which relies on a front source and a rear source to cancel rearward energy, the latter of which is inverted and delayed. That the out-of-phase rear-wave cancels rear output, but it also slightly reduces forward output, meaning more excursion is required for the same SPL. This explains the increase in distortion just above the crossover when you really crank them. That said, it’s a very robust driver with excellent power handling, as shown by its low power compression even at much higher levels (see Erin's and SoundStage's measurements). As others have pointed out, this distortion isn't audible at typical listening levels. You'd have to push them quite far before it becomes noticeable.

In the deep bass, distortion is actually very low, especially when you consider the size of the speaker and the fact that it uses "only" two 8" subwoofers. These are OEM variants of the Wavecor SW223, which are actually of very quality. Published distortion figures of the 8c come from free-field measurements, where the woofers work about 6 dB harder than they would in a typical rooms. When placed near the front wall, as intended, the 8c benefits from Boundary Coupled Bass, which significantly eases the load on the woofers. The 8c also extends very low in frequency, so the drivers need to move more air at the lowest octaves, which naturally increases distortion. Some manufacturers reduce bass output at higher playback levels to keep distortion in check. While that approach can be effective, it also alters the tonality. We chose not to go that route. What goes in is what comes out, with no surprises.

Could a higher performance driver (e.g. Purifi) improve that distortion behavior? I'm sure it would drive BOM through the roof, but certainly an interesting thought.

 

[Martijn Mensink]

+3db in output when configured correctly. Basically when the delay is set correctly for each frequency, the sound waves used to cancel excess dispersion pattern meets with the direct sound which results a +3db boost.

That's a common misunderstanding. A properly implemented active cardioid does not deliver a +3 dB boost in output compared to a passive cardioid. When both are correctly configured, their forward output and rearward cancellation are essentially the same. The real difference is in the difficulty of implementation. Passive cardioids are much harder to get right, and most designs fall short of the performance achieved by active systems. Ours doesn't.

 

[sigbergaudio]

In the deep bass, distortion is actually very low, especially when you consider the size of the speaker and the fact that it uses "only" two 8" subwoofers. These are OEM variants of the Wavecor SW223, which are actually of very quality.

Same bass driver we use in the Sigberg Audio Saranna (though in a ported configuration), very impressive driver that extends deep and with high linear excursion.

 

[Martijn Mensink]

Could a higher performance driver (e.g. Purifi) improve that distortion behavior? I'm sure it would drive BOM through the roof, but certainly an interesting thought.

Purifi drivers are very low distortion. Therefore, the short answer is yes. However, the benefit would be relatively small. If you want more output from a speaker like this, there are more effective ways.

 

[Blockader]

That's a common misunderstanding. A properly implemented active cardioid does not deliver a +3 dB boost in output compared to a passive cardioid. When both are correctly configured, their forward output and rearward cancellation are essentially the same. The real difference is in the difficulty of implementation. Passive cardioids are much harder to get right, and most designs fall short of the performance achieved by active systems. Ours doesn't.

Since we've got you here, would you care to explain then why active cardioid designs are preferred over passive cardioid setups in PA applications, where maximum SPL and lower sensitivity have the highest priorities? Could this be related to the roll-off below the tuning frequency of the cardioid slots?

 

[sigbergaudio]

Since we've got you here, would you care to explain then why active cardioid designs are preferred over passive cardioid setups in PA applications, where maximum SPL and lower sensitivity have the highest priorities? Could this be related to the roll-off below the tuning frequency of the cardioid slots?

PA cardioid systems are (to my knowledge) primarily cardioid bass systems, rather than cardioid speakers, so essentially subwoofers. And bass is more effectively produced by a sealed or ported system rather than a passive cardioid chamber.

Put differently; The cardioid effect itself can be just as effective in a passive system. But creating cardioid slots in a bass speaker / subwoofer isn't a great idea because it ruins the efficiency of the primary / forward sound.

 

[sigbergaudio]

@Blockader And this is also a tradeoff in capacity. What you'd typically see is a stack where you get two forward facing subwoofers and one facing rearwards. Which means you're in theory trading 33% of the capacity to create the cardioid pattern.

 

[MKR]

That's a common misunderstanding. A properly implemented active cardioid does not deliver a +3 dB boost in output compared to a passive cardioid. When both are correctly configured, their forward output and rearward cancellation are essentially the same. The real difference is in the difficulty of implementation. Passive cardioids are much harder to get right, and most designs fall short of the performance achieved by active systems. Ours doesn't.

Thank you Martijn for chiming in here! So if passive cardioid more difficult to implement, then why even go passive over active? There must be some benefit?

 

[Robocop]

Has anyone used subwoofers with the 8c's?

It seems no one has or admits to this. Nothing on the web regarding this.

 

[Purité Audio]

A few customers do, the 8Cs have a ‘sub’ out.
Keith

 

[MatrixS2000]

A few customers do, the 8Cs have a ‘sub’ out.
Keith

Is that functioning now? I thought it was still only a placeholder for future use.

 

[Purité Audio]

It’s always been functioning, I believe D&D are working to include filtering options high pass/low pass etc.
Keith

 

[MatrixS2000]

It’s always been functioning, I believe D&D are working to include filtering options high pass/low pass etc.
Keith

Right sorry, I should have worded it better. So we are still waiting...

 

[Sal1950]

Right sorry, I should have worded it better. So we are still waiting...

There's always so many options for subwoofer filtering either at the preamp or the subwoofer, more. I
don't imagine there's too much pressure on D & D to get it finalized in development. ?

 

[muslhead]

Has anyone used subwoofers with the 8c's?

It seems no one has or admits to this. Nothing on the web regarding this.

I have but the final result for me was it sounds better without. Could have been my integration was poor

 

[Robocop]

I suspected that muslhead, actually that its been designed optimally as a complete package. Adding subs would be tricky.

I run a minidsp Flex so would use this as crossover. One would need very good subs to match the 8c's for a start. I do have these in the JLAudio F112's.

The crossover point is another one. One would only be augmenting the 10 to 30hz region. So perhaps around 40 to 50hz. If I didn't have the subs I wouldn't bother.

I can't hear the 8c's in NZ as far as I know there are none here. This doesn't bother me as the last speakers I bought was the same situation.

Optimally would be connecting them direct to the 8c's with filters.

 

[muslhead]

I suspected that muslhead, actually that its been designed optimally as a complete package. Adding subs would be tricky.

I run a minidsp Flex so would use this as crossover. One would need very good subs to match the 8c's for a start. I do have these in the JLAudio F112's.

The crossover point is another one. One would only be augmenting the 10 to 30hz region. So perhaps around 40 to 50hz. If I didn't have the subs I wouldn't bother.

I can't hear the 8c's in NZ as far as I know there are none here. This doesn't bother me as the last speakers I bought was the same situation.

Optimally would be connecting them direct to the 8c's with filters.

you hit it on the nose.
I had great subwoofers, used a minidsp but no matter where i set the xover i couldnt get them dialed in.
I tried from 30 up to 80 and eventually gave up, sold the subs and got the 8c's perfected for my room (thanks to Martijn) and was happy as a clam with the final result.

 

[Sal1950]

I would imagine the 8C's would be very difficult to integrate with a sub since they go down so low. Unless you have a very large room and roll off the bass in the 8Cs, what your libel to end up with could be very muddy bass.

 

[markstein]

I could Imagine that the 8C would benefit from 1-2 closed subs at the back of the listening position (similar to the Welti 4 sub setup), with the 8C operated full range, to make the bass more even across more than one listening positions. Optimization can be done with MSO. Positive effect, you will need to shelf down the bass due to the additional subs, reducing the 8C distortion in this area.