AsciLab C5B Review.

[Matt_Holland]

Hello guys. Thanks for watching our tiny son. and Thanks to @Nuyes.

I've seen some of you concern about very low impedance at midbass range and steep phase at bass range.
It was also my concern too while designing crossover. It is 2-way and has LR4 XO at 1.1kHz. To get exactly matched phase each drivers at XO point and not to suck out midbass, We had to use quite large cap and low DCR air core coil. That's the main factor for the C5B having that low impedance.

We had another way to use 8ohm version woofer.
But then it must has -3dB lowered sensitivity. It is 80dB/2.83V@1M. We didn't want to design that low sensitivity.
And also bass alignment of 8ohm version doesn't fit to our purpose size.

So we chose 4ohm version though it has quite low minimum impedance.
Actually we don't concern about that now. Because it is only 5", 50W Power handling driver.
Even though it has hard to drive impedance, you don't really need much power.
If your amp is lack of power to drive this speaker, Please. There are a lot of great amps these days.

I want to share a practical result by 2 different amps. One is Topping PA5ii, and the other one is NAD C298(Purifi amp).
I measured with STEP Sine Sweep from 1V to 20V, 1V step.
20V is 100W at 4 ohm. Yes, I didn't regard about crest factor. but only 20V is pretty high level for this speaker, about 101dB @ 1M.



View attachment 409668View attachment 409669

Now, you can see almost no difference between the two results.
NAD C298 has much high headroom to drive 20V. and PA5ii has Maximum 120W output @ 1%.
Though PA5ii was driven almost max level. There is no significant compression.




View attachment 409670View attachment 409671


And here is distortion at 20V.
It would be more important to concern speaker output capability before Amp output.

So, Yes. I also concerned about low impedance to while designing.
But in practical situation, don't have to worry about that.
You only need to worry about something like 2ohm 1000W subwoofer. And yes again, We won't do that when we design subwoofer.


C5B is our entry model. There will be some reviews of our bigger models C6B and A6B using Purifi woofer.
Please stay tuned. Nuyes is preparing a lot of datas. Thanks for watching us again.

I just wanted to say I applaud your efforts in interacting with this community (and presumably the wider one). It’s a breath of fresh air, just like the other manufacturers who communicate in a similar, detailed and honest way on these forums.

You deserve much success.

 

[thewas]

The EPDR dips to 1 ohm and it spends a wide area below 2 ohms. A class AB amp will probably get very hot.

Seriously now, an EPDR lower than 2 Ohm between 80 and 800 Hz isn't really an easy load for many middle class amps.

 

[Chr1]

Apologies for my ignorance, but is it not just a case of over-specing on the amplifier power required? Or is there more to it?
Surely amp topology is irrelevant?

 

[Scgorg]

Apologies for my ignorance, but is it not just a case of over-specing on the amplifier power required? Or is there more to it?
Surely amp topology is irrelevant?

Amp topology is in fact relevant in this case. The calculation of EDPR is specifically one that applies to class AB and B amps. Jack Oclee-Brown of KEF shared a concise writeup of how it is derived on this forum. His comment and file in this link: https://audiosciencereview.com/foru...as-started-calculating-epdr.15497/post-584683

 

[AdamG]

Even Hypex NC500 monoblocks which I use with 80v rails, they don't like Wilson Alexia type of loads you loose a lot of bass grunt). I use a linear BJT amp on those and you can hear it even though it's less than half the 8ohm wattage than the Hypex's are. The linear BJT amps can just give more constant current drive into those low loadings. As @DanielT said that limits the type of amp to get the best out of them
https://www.audiosciencereview.com/forum/index.php?threads/ascilab-c5b-review.58753/post-2148188
Cheers George

Well that explains why almost the entire supply of Powered Subwoofers on the market employ “Class D” plate amps.

 

[Chr1]

Thanks. Begs the question : What about class G and H then?

 

[dfuller]

View attachment 409706
Seriously now, an EPDR lower than 2 Ohm between 80 and 800 Hz isn't really an easy load for many middle class amps.

Especially because there's a fair amount of energy in most program material in that region. That could get dicey without a surprisingly beefy amp.

Thanks. Begs the question : What about class G and H then?

Most are rail switching/tracking AB, so I'm going to guess it still has some relevance.

 

[Jim Taylor]

So you think between 2 similar wattage amps driving the Wilson Alexia's which has a .9ohm low bass loading.
Fosi V3 and the Gryphon Antilleon, your going to be hard pressed to pick the differences between them even at medium listening level, good luck with that.
These C5B's have quite an nasty load, -phase angle & impedance between 80hz to 400hz
Cheers George

This thread may be of benefit:

Stereophile has started calculating EPDR.

https://www.stereophile.com/content/goldenear-brx-bookshelf-reference-x-loudspeaker-measurements And he is going back to previous reviews and adding this in. EPDR (Equivalent Peak Dissipation Resistance) takes the impedance and phase data and computes a new impedance that shows what equivalent...

www.audiosciencereview.com

I believe page 3 delves into the applicability to Class D.

 

[thewas]

Especially because there's a fair amount of energy in most program material in that region. That could get dicey without a surprisingly beefy amp.

Exactly, if it would be above 800 Hz I wouldn't be as worried.

 

[Purité Audio]

Not generally a fan of passive designs but obviously you have to consider speakers and power amp as ‘one’.
Keith

 

[Chr1]

So is it really the case that a quality, high/over powered class A/B, H would not be sufficient to power these.
These are pretty small speakers.
Seems weird.

 

[dfuller]

So is it really the case that a quality, high/over powered class A/B, H would not be sufficient to power these.
These are pretty small speakers.
Seems weird.

Enough power should be OK. It may just be well in excess of what you think you'd need.

 

[Chr1]

Surely this is always the case with difficult speakers tho?
Judicious use of the volume control being the order of the day. Consequent SINAD will doubtless be a consideration then too presumably.
Given Watts are cheap, these seem like very good speakers to me. I am now curious as to what, and therefore how much it costs to drive them properly...
Bring on the testing!
(Controlled obviously.)

 

[Matt_Holland]

View attachment 409706
Seriously now, an EPDR lower than 2 Ohm between 80 and 800 Hz isn't really an easy load for many middle class amps.

I know a really good website for finding amplifiers that are not middle class…

 

[Chr1]

(Cue: Vintage Monty Python sketch adapted to amplifiers)

 

[Matt_Holland]

(Cue: Vintage Monty Python sketch adapted to amplifiers)

This amplifier is DEAD.

 

[Matt_Holland]

(Cue: Vintage Monty Python sketch adapted to amplifiers)

If an amp can’t drive the new Ascilab it must have been designed by the ministry of silly amplifiers…

[I’m here all week]

 

[Chr1]

Indeed. Tho thinking of the one where they are lined up according to "class" and hence pecking order.

Question is : is it the same with amps tho?

All good. Got a mixture of A, A/B, H and D here, so quite happy to kick back and observe and learn from the ongoing awkward passive speaker amp class wars.
Splendid.

 

[DanielT]

These nice helpful sales people may be able to help with the type of amplifier that is suitable.

The bit about amps starts 1:01 into the video:

 

[AdamG]

These nice helpful sales people may be able to help with the type of amplifier that is suitable.

The bit about amps starts 1:01 into the video:

The reason this is so funny is because it’s bloody accurate and true.