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

[Vincia]

Que signifie « dynamique » ? Un amplificateur se définit essentiellement par sa puissance de sortie (quelle que soit l'impédance de charge), son bruit de fond et la linéarité de sa réponse. Quant au facteur d'amortissement, tous les amplificateurs modernes offrent des performances satisfaisantes à cet égard. Si votre ancien Rotel présente un défaut (ce qui n'est pas certain), il s'agit probablement d'un problème d'alimentation.

Puisque vous ne pouvez pas mesurer l'amplificateur vous-même, vous pourriez en emprunter un à un ami pour le testeur, ou en acheter un neuf, le testeur, puis le retourner ou revendre le Rotel. Votre Rotel pourrait se vendre environ 400 €. Par exemple, voici un amplificateur nettement plus puissant que votre Rotel et offrant d'excellentes performances. D'autres modèles affichent de meilleures performances, mais les différences sont inaudibles. https://www.audiosciencereview.com/forum/index.php?threads/audiophonics-mpa-s250nc-amp-review.45306/ 471 € 250 W

By dynamics, I meant the ability to respond easily to transients. This may be a technically incorrect term. We young people in the 1980s were careful to buy amplifiers with high current reserves! Perhaps today, with Class D, this problem can be considered overcome.

 

[melomane13]

By dynamics, I meant the ability to respond easily to transients. This may be a technically incorrect term. We young people in the 1980s were careful to buy amplifiers with high current reserves! Perhaps today, with Class D, this problem can be considered overcome.

high current reserves is the capacity to deliver power on low impedency ... so it is power capabilitys. this can be mesured, for exemple:

 

[Cote Dazur]

By dynamics, I meant the ability to respond easily to transients. This may be a technically incorrect term. We young people in the 1980s were careful to buy amplifiers with high current reserves! Perhaps today, with Class D, this problem can be considered overcome.

The “problem” was never there.
If you had an issue with the Rotel it would be apparent on all music, not just the music that is the most difficult to reproduce.
Since you have a fix set up, you might have to accept the compromise and enjoy what you have, you could be amazed what your brain can do to what you hear f you decide to enjoy instead of thinking your amplifier is at fault.

 

[peng]

high current reserves is the capacity to deliver power on low impedency ... so it is power capabilitys. this can be mesured, for exemple: View attachment 556749

I would say technically, it is more about current capability, literally, than “power”. Higher current does not always imply higher power, though the 2 are related. I wish that chart had used the term VA instead of Watts.

 

[Ruediger]

I would have the speaker crossovers checked out and possibly re-made. Depending on someone available to do so. Good speakers are expensive and the crossover could be sent somewhere. It's worth the time and work.

I would replace the Rotel with a Vibelink, IOM, Hypex or whatever. That's rather inexpensive.

 

[Matt_Holland]

Does anyone know if the PMC GB1 was related to the stand-mount DB1? They look very similar and are of similar vintage. I had a pair of DB1 for a while (second hand but barely used) and they were terrible. No bass (what was there was resonant annd annoying) and a very uneven mid and treble. There was plenty of detail and Imaging was good because any pair of speakers can image well (one reason we should never judge a speaker seriously when listening to a pair in stereo), but they were so inconsistent and really fell apart as soon as you played something with a lot going on.

 

[mglobe]

Here are measurements on the PMC GB1. Looking at the frequency response makes me think the best bang for the buck would be a speaker change.

https://www.soundstagenetwork.com/measurements/pmc_gb1/

I’m assuming the OP is somewhere in the EU, but that’s not clear to me. It would help us to know location so that we can make suggestions that are available, room size & distance from listening position to speakers, and preferred listening volume.

 

[Matt_Holland]

Here are measurements on the PMC GB1. Looking at the frequency response makes me think the best bang for the buck would be a speaker change.

https://www.soundstagenetwork.com/measurements/pmc_gb1/

I’m assuming the OP is somewhere in the EU, but that’s not clear to me. It would help us to know location so that we can make suggestions that are available, room size & distance from listening position to speakers, and preferred listening volume.

Those transmission lines are horrible! Has the cancellation that PMC always claimed they avoided with their ATL. The only good thing about the data shown is the off-axis curves look consistent so there’s a chance the speaker could be EQ’d successfully.

 

[mglobe]

Those transmission lines are horrible! Has the cancellation that PMC always claimed they avoided with their ATL. The only good thing about the data shown is the off-axis curves look consistent so there’s a chance the speaker could be EQ’d successfully.

I’d move on to other speakers rather than try to “fix” those.

 

[Vincia]

Here are measurements on the PMC GB1. Looking at the frequency response makes me think the best bang for the buck would be a speaker change.

https://www.soundstagenetwork.com/measurements/pmc_gb1/

I’m assuming the OP is somewhere in the EU, but that’s not clear to me. It would help us to know location so that we can make suggestions that are available, room size & distance from listening position to speakers, and preferred listening volume.

Yes, EU. Other information in the op.

 

[Vincia]

I’d move on to other speakers rather than try to “fix” those.

Please, suggest a passive speaker with the same foootprint and To position near the wall.

 

[Vincia]

Those transmission lines are horrible! Has the cancellation that PMC always claimed they avoided with their ATL. The only good thing about the data shown is the off-axis curves look consistent so there’s a chance the speaker could be EQ’d successfully.

I attended about 700 symphonic music concerts in many different concert halls in my life. I know what the live sound of an orchestra is. I am quite satisfied with what my system gives me. The latest changes (see op) allow me a satisfying home listening. I was wondering if a modern amplifier could make me improve something else. I will also do some room correction tests. Anyway, thanks to everyone for the advice you give me.

 

[melomane13]

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.

 

[mglobe]

Please, suggest a passive speaker with the same foootprint and To position near the wall.

Not sure about the footprints, nor the availability in the EU, but:

Floorstanders
Polk Reserve R500
Arendal 1961 Tower
Elac Debut 3.0 DF62
Revel F35

Bookshelves -- Will need stands but similar footprint.
Ascend Acoustics Sierra 1 V2
Ascilab C6B
Revel M105
Dynaudio LYD 5

 

[Vincia]

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.

Good. I'll try asap.

 

[DanielT]

Since the speakers are the most important part of the chain (along with EQ, room acoustics treatments, and good music recordings), perhaps new speakers? If you want floor-standing speakers: Heco Aurora 1000. They are right at the limit of your budget.
I can say with high confidence that they are better than your current PMC GB1.

HECO Aurora 1000 Floorstanding Loudspeaker Review

The German made Heco Aurora 1000 floor-standing speakers ($799/ea) were put through the wringer with our in depth measurement testing and yielded surprising results. Are these the speakers to get?

www.audioholics.com

 

[Matt_Holland]

KEF R5 Meta
Measurements

 

[mglobe]

KEF R5 Meta
Measurements

View attachment 557224

THIS!

 

[DanielT]

KEF R5 Meta
Measurements

View attachment 557224

R5 Meta; £3,200/ Pair

But:
TS , @Vincia : The budget should be no more than €1,000-1,500, staying below that if possible.

Used ones might come close to the TS's budget, though.

 

[Vincia]

KEF R5 Meta
Measurements

View attachment 557224

Based on the answers received so far, I can make three considerations:
1. - Everyone considers the replacement of the Rotel with more modern class D amps unconvincing. My question then is: what advantages have brought more than thirty years of technology development on amplifiers? Maybe it only served to keep production costs low? Are the improvements in measurements not appreciable by the human ear?
2. - Many suggest changing the speakers. What should I pay attention to by looking at the charts? For example: what are the significant differences between the PMC GB1 (https://www.soundstagenetwork.com/measurements/pmc_gb1/) and those of KEF R5 Meta (https://www.spinorama.org/speakers/KEF R5 Meta/ErinsAudioCorner/index_eac.html)?
3. - In post #33 @melomane13 suggests to put the crossover frequency (speakers x subwoofer) between 100 and 200 Hz. Could this improve the response considering that the curve of GB1 PMCs (https://www.soundstagenetwork.com/measurements/pmc_gb1/) at about 165 Hz has a reduction of 10 dB?