Ascilab C6B Speaker Review

[Purité Audio]

Revel make fine measuring loudspeakers, but no loudspeaker is ever ‘perfect’.
Keith

 

[holbob]

I have been following this thread with interest, but for all the advanced technology employed I'm sure that most people, listening to music in their own home, would not be able to distinguish this speaker from the excellent Revel M106 released 13 years ago and about which Amirm concluded his review by saying "The Revel M106 is one of the most perfect bookshelf speakers I have heard."

Revel M106 Bookshelf Speaker Review

This is a review and detailed measurements of the Revel M106 bookshelf speaker. It was kindly purchased and drop shipped to me. It is not a new sample but came to me with full packaging and protective wrapper. The M106 costs US $1,000 each or $2,000 for a pair. It is only sold through dealer...

www.audiosciencereview.com

I know this speaker is no longer made but my main point is that we already reached perfection 13 years ago.

I've had both. I prefer the ascilab as the M106 had something grating or harsh in the higher frequencies that I couldn't get rid of.

On the subject of subwoofers with the C6B, it would be helpful if members spoke about room size in terms of actually needing sub(s)—especially in small spaces like mine (3.6m x 4.1m / 34 m³)—as FOMO can hit hard unnecessarily. Erin does this as well, apparently everyone needs subs in all situations. I have never seen the need after comparing a 10" THX against speakers years ago: the extra excursion was not audible in 99% of music and the distortion was no lower

 

[Davey2156]

I have been following this thread with interest, but for all the advanced technology employed I'm sure that most people, listening to music in their own home, would not be able to distinguish this speaker from the excellent Revel M106 released 13 years ago and about which Amirm concluded his review by saying "The Revel M106 is one of the most perfect bookshelf speakers I have heard."

Revel M106 Bookshelf Speaker Review

This is a review and detailed measurements of the Revel M106 bookshelf speaker. It was kindly purchased and drop shipped to me. It is not a new sample but came to me with full packaging and protective wrapper. The M106 costs US $1,000 each or $2,000 for a pair. It is only sold through dealer...

www.audiosciencereview.com

I know this speaker is no longer made but my main point is that we already reached perfection 13 years ago.

It might be close to perfection for a 'bookshelf' speaker. But that leaves it way short of perfection.....and even well short of larger non-bookshelf speakers like the Salon2.
Small, two-way box speakers are highly limited by their very nature. This Ascilab speaker is entry-level, at best.

 

[RickS]

I have been following this thread with interest, but for all the advanced technology employed I'm sure that most people, listening to music in their own home, would not be able to distinguish this speaker from the excellent Revel M106 released 13 years ago and about which Amirm concluded his review by saying "The Revel M106 is one of the most perfect bookshelf speakers I have heard."

Revel M106 Bookshelf Speaker Review

This is a review and detailed measurements of the Revel M106 bookshelf speaker. It was kindly purchased and drop shipped to me. It is not a new sample but came to me with full packaging and protective wrapper. The M106 costs US $1,000 each or $2,000 for a pair. It is only sold through dealer...

www.audiosciencereview.com

I know this speaker is no longer made but my main point is that we already reached perfection 13 years ago.

Point taken, but there is a matter of value as well. Revel’s successor to the M106 is a M146. They are $3000 a pair currently. The review speakers are less than half that price.

 

[Bernd]

If they sound as good as the measurements suggest then these loudspeakers are a real deal not to say a bargain.

 

[RPG]

If they sound as good as the measurements suggest then these loudspeakers are a real deal not to say a bargain.

With all the usual caveats, they do. Note that I also have two well-integrated/optimized SVS PC2000 Pro subs low passed at 50hz along with some eq's particular to my irregularly shaped room.

 

[Karlinamillion]

Excuse potentially daft question, but how close could the C6B's back (ie the back of the cabinet) to the wall behind it?

 

[Purité Audio]

I don’t believe the PR makes any difference to the usual between 10-60cm reccomendation.
Keith

 

[YouDontHaveEnoughBass]

Couple of centimetres to ensure the cone never touches the wall and there’s a small air gap is all you need

 

[Karlinamillion]

Excellent, thank you Keith and Mr Bass

 

[Matt_Holland]

Excellent, thank you Keith and Mr Bass

But which one of them is right?

 

[YouDontHaveEnoughBass]

We can work it out

To not mess with a port tuning you need the area the air will be going out to to be greater than the area of the port

Typically ports are ~5cm across meaning ~20cm area - this port will have a circumference of ~16cm meaning you only need ~1.25 cm clearance to not mess with port tuning; this is why bottom ported speakers get away with surprisingly slim 'slots' going around the base

Going back to the passive radiator for the C6B, we've got a much greater perimeter of ~50cm meaning you only need half a centimeter of air gap to avoid messing with tuning frequency; by having a couple centimeters gap to ensure the cone never touches the wall you've comfortably given it plenty of breathing room to behave as it should

 

[Matt_Holland]

We can work it out

To not mess with a port tuning you need the area the air will be going out to to be greater than the area of the port

Typically ports are ~5cm across meaning ~20cm area - this port will have a circumference of ~16cm meaning you only need ~1.25 cm clearance to not mess with port tuning; this is why bottom ported speakers get away with surprisingly slim 'slots' going around the base

Going back to the passive radiator for the C6B, we've got a much greater perimeter of ~50cm meaning you only need half a centimeter of air gap to avoid messing with tuning frequency; by having a couple centimeters gap to ensure the cone never touches the wall you've comfortably given it plenty of breathing room to behave as it should

I agree that PR can be closer to a boundary than a port. Could you show your working out though please.

 

[YouDontHaveEnoughBass]

I did hash over some things to get to the conclusion faster to be fair, anyone just looking for practical advice can skim through my original comment as a TLDR, with this going more into the maths

Area of port is easy; it's the cross-section of the cylinder:

So for a fairly standard ~5cm port we get ~20cm area (radius being half the diameter):

For the area behind the port where the sound escapes out the side, it's best to visualise that same cylinder we have above only now we care about the area of the pink wall of the cylinder:

So here h would be the distance between the back of the speaker and the wall; to get the width of this rectangle we need the circumference of the port:

This means that, for a distance of 1.25cm from the wall, we get a pink wall area of 1.25 * 15.71 = 19.64cm so just enough to beat the area of the port

Now if we switch our conventional ported speaker to the C6B, we still have the yellow and pink cylinder above only now the yellow cross sectional circle is the large race track shape of the PR (5 × 8 inches) so lets work out how big a circumference this will be:
5 inches = 12.7cm
8 inches = 20.32cm

The shape is two half-circles 12.7 across plus the straight sides between them which are 20.32 - 12.7 = 7.62cm long each, there's two of those straight lines so we're just working out the circumference of a 12.7cm circle and adding on 7.62 x 2

39.9 + 7.62 + 7.62 = 55.14cm

Okay! So now we know the perimeter of the PR is 55.14cm we can go back to our yellow and pink cylinder above to work out area

If we have a 0.5cm gap between speaker and wall, the area would be 0.5 x 55.14 = 27.57 which is already plenty bigger than the area of an equivalent port

By giving 2cm space, the cone of the PR can move out by 15mm (already past its rated max excursion of 11mm) and still give good clearance

 

[LiveTek]

already past its rated max excursion of 11mm

SB also lists their xmax in peak to peak for some reason, most manufacturers list one way excursion. So it's really only around 5.5mm of cone travel that needs to be cleared.

 

[YouDontHaveEnoughBass]

Yeah I tried to give conservative estimates where possible; realistically in a small-medium room where they're placed close to a wall they won't have enough watts pumped through them to come close to that anyway it'd be deafeningly loud in there + distortion would be horrendous

 

[Matt_Holland]

I did hash over some things to get to the conclusion faster to be fair, anyone just looking for practical advice can skim through my original comment as a TLDR, with this going more into the maths

Area of port is easy; it's the cross-section of the cylinder:
View attachment 551871
So for a fairly standard ~5cm port we get ~20cm area (radius being half the diameter):
View attachment 551874

For the area behind the port where the sound escapes out the side, it's best to visualise that same cylinder we have above only now we care about the area of the pink wall of the cylinder:
View attachment 551876
So here h would be the distance between the back of the speaker and the wall; to get the width of this rectangle we need the circumference of the port:
View attachment 551877

This means that, for a distance of 1.25cm from the wall, we get a pink wall area of 1.25 * 15.71 = 19.64cm so just enough to beat the area of the port

Now if we switch our conventional ported speaker to the C6B, we still have the yellow and pink cylinder above only now the yellow cross sectional circle is the large race track shape of the PR (5 × 8 inches) so lets work out how big a circumference this will be:
5 inches = 12.7cm
8 inches = 20.32cm

The shape is two half-circles 12.7 across plus the straight sides between them which are 20.32 - 12.7 = 7.62cm long each, there's two of those straight lines so we're just working out the circumference of a 12.7cm circle and adding on 7.62 x 2

View attachment 551885

39.9 + 7.62 + 7.62 = 55.14cm

Okay! So now we know the perimeter of the PR is 55.14cm we can go back to our yellow and pink cylinder above to work out area

If we have a 0.5cm gap between speaker and wall, the area would be 0.5 x 55.14 = 27.57 which is already plenty bigger than the area of an equivalent port

By giving 2cm space, the cone of the PR can move out by 15mm (already past its rated max excursion of 11mm) and still give good clearance

Thanks for taking the time to expand n this further. I understand the area calculations but I still don’t understand your reasoning. I would have thought that the size of the cabinet is also a factor as this defines the overall extension of the port effect.

Also what is the thinking/maths behind:

“To not mess with a port tuning you need the area the air will be going out to to be greater than the area of the port”

 

[YouDontHaveEnoughBass]

I wouldn't worry about cabinet size too much; as the waves travel further away from the port across the wall the radius of the circle grows with distance and therefore so does circumference and so area, below shows the worst-case example I gave for a 5cm port speaker only 1.25cm from the wall (looking onto the back of the speaker):

At double area of port it's really not acting as much of a port extension any more, and by the time you get to 3x or 4x the area it's doing negligible stuff (think of it like a rapidly flaring out port extension rather than a tubular one)

I gave worst-case figures in my calcs in the comment above; realistically the PR isn't gonna be moving more than a few mm so we can safely assume at least 1.5cm of distance cone to wall - plug in the numbers from above and we get 1.5 x 55.14 = 82.71 which is already more than 4x the area of the equivalent port at the worst spot right at the edge of the PR; as the waves travel away from the PR that area grows and grows

Any tiny changes to tuning frequency that might happen would be more than offset by the boundary gain from the wall and can be considered free bass extension

 

[Nopiano]

Any tiny changes to tuning frequency that might happen would be more than offset by the boundary gain from the wall and can be considered free bass extension

Is that another way of saying that the boominess arising from close placement to a wall will mean in practice you’ll never place a port close enough to the front wall for it to affect the tuning?

 

[YouDontHaveEnoughBass]

Nah, see my username

Jokes aside, it *might* activate a room mode more than pulled-out placement but that's a far easier problem to fix than issues from having them pulled out such as SBIR cancellations or overall deficient bass

These speakers are over a grand; an extra hundred for a calibrated mic to identify and cut any big peaks in bass is a small cost in comparison that'll yield fantastic benefits in response