Rotel RB-870BX vs class D (hypex/Purifi…)

[DanielT]

the Ascend Sierra-1 V2 are nice, but:
What motivates the Vincia is a lack of clarity in the fortissimo passages, so more emissive surface area is needed.
Since the woofer in the Ascend is identical to the one in the PMC, compared to the 7.5-inch woofer of the Buchardts,
which represents an emissive surface 2.25 times larger, the choice is obvious.

Perhaps, but Vincia does have subwoofers.

Something played or sung very loudly, with high dynamics, especially if you crank up the volume, that in itself demands a lot from your hi-fi system. You really ought to check if the setup—amp and speakers—can handle high SPL (while maintaining reasonably low distortion).

Buchardts 7.5-inch woofer might have slightly higher sensitivity then the Sierra-1 V2 woofer but it’s hardly an SPL monster. That woofer—albeit a really good one— is rated for 70 watts of power handling:

7½″ SATORI MW19P-8 / Paper - Sbacoustics

Vented aerodynamic cast aluminium chassis for optimum strength and low compression, proprietary cone material with EGYPTIAN PAPYRUS™ fibres made in-house.

sbacoustics.com

If you like playing highly dynamic music at deafening volumes, you should look into high-power-handling PA bass drivers/woofers paired with compression drivers.
Maybe high-sensitivity horn speakers, and so on. I know that’s not an option for the Vincia, but I thought I’d mention it anyway.
By the way, horn speakers the size of a refrigerator (or larger) aren't for everyone. These are the compromises one is forced to make—including regarding one's wallet.
(In my case, I also have to consider the neighbors in the apartment complex.)

 

[Ruediger]

"The €4,000 budget is substantial, but the rather limited dimensions severely restrict the possibilities. I also suspect that the 'industrial' look of pro speakers wouldn't go down well with the rest of the family. I would therefore stick to passive bookshelf speakers, keeping the subwoofer and amplifier." Kef R3 meta 2400€ in blue / white / black / wood. The bass-reflex port is in the back, but foam bu

I think those KEF would be a good choice. In that price area around 2.5k I would also look at the Dali Rubikore 2.

It depends a bit where the OP is and if all recommended speakers are available to him.

A while back I looked into Ascend speakers and IIRC that whould have meant shipping over the big pond.

 

[melomane13]

Perhaps, but Vincia does have subwoofers.

One only for the moment , and the sub is actually filtred at 80hz. the problem isn't here, but at 80/200 hz... this is the reason i have proposed to set the sub crossover more high, for testing.

Buchardts 7.5-inch woofer might have slightly higher sensitivity then the Sierra-1 V2 woofer but it’s hardly an SPL monster. That woofer—albeit a really good one— is rated for 70 watts of power handling:
View attachment 557676

7½″ SATORI MW19P-8 / Paper - Sbacoustics

Vented aerodynamic cast aluminium chassis for optimum strength and low compression, proprietary cone material with EGYPTIAN PAPYRUS™ fibres made in-house.

sbacoustics.com

70w IEC 268-5 , so they are more on peak. with highpass filter at 100hz, they can get 280W peak ( music) , so near 114db/m

 

[Vincia]

Good. I'll try asap

Here’s a slightly different piece of advice. Given the room volume and the small 14 cm woofer, I think what you’re hearing as muddy or congested during full orchestral passages is simply the driver hitting its Xmax limits.

First, I’d try crossing over the sub and satellites higher—around 100 Hz 120 hz or even 200 Hz— to relieve as much strain as possible from the 14 cm driver. I’d also try plugging the port to eliminate any resonance, since the bass is now handled entirely by the subwoofer, making the transmission line redundant. However, this approach has its limits due to the high crossover frequency, which could make the subwoofer localized. Room correction would still be helpful.

I ran some initial tests with WiiM RoomFit—without closing the transmission line (TL)—using various crossover frequencies:
P0C: No Sub
P1C: 80 Hz
P2C: 100 Hz
P3C: 120 Hz
In some earlier attempts, I had set the WiiM crossover to 80 Hz, while the KEF Kube 12b was set to half volume and 100 Hz crossover frequency. Also—perhaps mistakenly—I had enabled the "no-boost" function in the WiiM correction settings. Now, the KEF’s low-pass frequency is at its maximum setting and the volume is at two-thirds; the "no-boost" function on WiiM is disabled.
I can't really interpret these curves, but to my ears, things have improved significantly, especially in the low-end range. Jazz and pop tracks now have much more substantial and defined bass. With symphonic music, there is still some muddiness during orchestral climaxes, but the music is very enjoyable: the orchestra is spread out before me from right to left, and the various sections are clearly distinguishable.
P2C (100 Hz crossover) seems preferable to me, though the differences are minimal.
What are your observations from a technical standpoint? What would you suggest?
The dip at 150 Hz is gone (https://www.soundstagenetwork.com/measurements/pmc_gb1/).

 

[melomane13]

I find that the correction (automatic?) made to the peak at 1kHz and to the dip centered at 2.5kHz is very well linked to the anechoic measurement from soundstagenetwork, should perfectly refine the timbre.
there are no particular differences between 100Hz and 120Hz, use whichever you prefer.
I wouldn't do anything more, except possibly change the speakers if the small remaining imprecision in the fortissimo remains difficult to bear.
for that you necessarily need more radiating surface, because symphonic music is very demanding in the 100Hz/500Hz band.
your small 14cm speakers do what they can. to have better you need a 7 or 8 inch, the Buchardt seems to be ideal, or the KEF R3 Meta (but too large), maybe there are other speakers that could do the job.

 

[DanielT]

I hadn't intended to replace the speakers, but it is an option worth considering. I have a few constraints. The footprint—including the base and spikes—must be no larger than 20 cm (W) by 26 cm (D). The bass reflex port needs to be front-facing because the speaker will be placed against the wall. I don't think it will be easy to find a high-quality tower speaker that meets these constraints—the very same ones that led me to buy the PMC GB1s back in 2004. Do you have any speakers of this type in mind?

I’m curious. Is it not possible for you to rearrange the furniture in your room so you could fit in slightly larger speakers?

 

[Cote Dazur]

With symphonic music, there is still some muddiness during orchestral climaxes, but the music is very enjoyable: the orchestra is spread out before me from right to left, and the various sections are clearly distinguishable.

As I was reading this, I was wondering if, since you are in evolution and comparison mode, you are always listening to the same piece of "symphonic music". If it is the case, is it possible that you are evaluating a recording where you noticed "some muddiness", frequent in symphonic recordings.
We have a tendency to do that when evaluting/compairing.
Maybe it is a good idea, at this time, to just play different symphonic recordings to check that you are not chasing your tail.

 

[melomane13]

Maybe it is a good idea, at this time, to just play different symphonic recordings to check that you are not chasing your tail.

also check with good hearphones...

 

[Vincia]

As I was reading this, I was wondering if, since you are in evolution and comparison mode, you are always listening to the same piece of "symphonic music". If it is the case, is it possible that you are evaluating a recording where you noticed "some muddiness", frequent in symphonic recordings.
We have a tendency to do that when evaluting/compairing.
Maybe it is a good idea, at this time, to just play different symphonic recordings to check that you are not chasing your tail.

Fair point. I'll try with other recordings.

 

[Vincia]

I find that the correction (automatic?) made to the peak at 1kHz and to the dip centered at 2.5kHz is very well linked to the anechoic measurement from soundstagenetwork, should perfectly refine the timbre.
there are no particular differences between 100Hz and 120Hz, use whichever you prefer.
I wouldn't do anything more, except possibly change the speakers if the small remaining imprecision in the fortissimo remains difficult to bear.
for that you necessarily need more radiating surface, because symphonic music is very demanding in the 100Hz/500Hz band.
your small 14cm speakers do what they can. to have better you need a 7 or 8 inch, the Buchardt seems to be ideal, or the KEF R3 Meta (but too large), maybe there are other speakers that could do the job.

I agree with you: this is the best my system can give. And I am quite satisfied, as I already enjoy listening to a lot of music (classical, pop, jazz).
Thank you for the suggestions you gave me, but I have one last question: how should the response curves in my room be evaluated from a technical pov?

 

[melomane13]

how should the response curves in my room be evaluated from a technical pov?

From a technical standpoint, a single measurement of frequency response at the listening position is not enough: you need to use REW (Room EQ Wizard) to analyze the full set of key curves—frequency response (SPL), time decay (Waterfall), phase, distortion and compression.
Of course, you could still improve it further—especially with speakers offering higher dynamic capability—but you're stuck with their dimensions and having to place them against the wall...

If you're happy with the sound right now, just stop tweaking and enjoy the music!