Rotel RB-1092 vs. RB-1572

[Wolfenstein 2k2]

Hi!

I need your advice: I have the chance to get a brandnew RB-1092 (1500 Euros incl. VAT). Another, even cheaper option would be to buy a brandnew RB-1572 although I prefer the looks of the RB-1092 (I currently own a RSP-1098 + RMB-1075).

Both amps will certainly deliver more than enough power to drive my Monitor Audio RX8 floorstanders. The question is: Are there any significant sound differences between those two generations of Rotel class D amps? I mean, have e.g. the ICE-modules improved over the past years?

I´ve read a lot of articles and threads. Some people claim that the 15 series class D amps sound "better" (tighter, warmer bass like most class A or A/B amps, less "annyoing" high frequency performance etc.). Others say that there are basically no big differences.

I know that the best case scenario would be to do a side by side comparison, but I don´t have the money to buy two amps (RB-1092 + RB-1572). I also have no dealer in my vicinity that could lend me one of those amps. That´s why I´m asking you: Have you had the chance to compare both amps at the same time? Are there any considerable tonal differences?

[Mikael]

Hi
Yes there are some sounds differents from the RB1092 to the RB1572. The 1092 has a more cold/controlled sound a little thin/hard in sound and the 1572 has a more warm/naturel sound. And I must say that I was blow away by the sound of the RB1572, it is that good. I myself did an AB test between the two amps today, because i wanted to hear the difference from the old ICEPower to the new modules.

But go and have a listen your self.

[Wolfenstein 2k2]

Monitor Audio uses ceramic-coated magnesium and alloy for their tweeters and cones. If I had to characterize the sound in combination with my RMB-1075, I would use the terms "detailed", "clearly defined bass", "analytic", "dynamic", "rather cold than warm", and "slightly emphasized high frequencies that are rather hard than soft".

So, in case you`re right, I´m not sure whether the RB-1092 would be a good match for my Monitor Audio speakers.

EDIT:
Will borrow an unused RB-1092 at the weekend. My dealer told me to "break-in" the amp approx. 50-100 hours 8O

[Carrotman]

Hi
<snip>And I must say that I was blow away by the sound of the RB1572, it is that good. I myself did an AB test between the two amps today, because i wanted to hear the difference from the old ICEPower to the new modules.

The 1572 isn't using the new ICEpower modules (the ASX-series) it is using the old A-series so you are actually comparing "old" vs. "older" - not that you should let that stop you .
However, I completely agree with your evaluation of the sound. To me, the 1000ASPs in the 1092 plays "hi-fi" whereas the 500As in the 1572 play "music".


/U.

[Wolfenstein 2k2]

Correct.

The RB-1092 is using one B&O ICEpower 1000ASP module with built-in power supply for each channel.

http://www.icepower.bang-olufsen.com/en/solutions/speaker/ASP_SERIES

The RB-1572 however is using one B&O ICEpower 500A module without built-in power supply for each channel. In this case the power supplies were developed by Rotel as far as I know.

http://www.icepower.bang-olufsen.com/en/solutions/speaker/A_SERIES

The newer ASX2 series comprises modules offering two-channel or bridgeable speaker drive. The "flagship" module (B&O ICEPower 250ASX2) is rated at 630W @ 8ohms in bridged mode or can deliver 2x 250W @ 4ohms. Maybe Rotel`s alleged successor to the RB-1091 / RB-1092 is going to use this module (?) provided that they´re actually planning to throw something bigger on the market than the RB-1572.

[Mikael]

Ok I thought that they used newer ones in the 15 series vs the 10 series. but anyway they are different, and I like the old ones best(1572)

What about the RB1562 vs RB1072, does the 1562 use older modules to like the 1572 compared to the 1072?

And where do you get the tech info about the Ice modules?

[mjb]

And where do you get the tech info about the Ice modules?

http://www.icepower.bang-olufsen.com/

[Mikael]

Thanks Mjb

But I meant what kind of modules that are inside the Rotel amps?

[Wolfenstein 2k2]

http://www.htguide.com/forum/showpost.php4?p=388072&postcount=10

Or simply read the following thread. Maybe you´ll find out which modules are used in the 15 series class D amps: http://www.htguide.com/forum/showthread.php4?t=29020

BTW: I´m really looking forward to tomorrow :T Can´t wait to hear the RB-1092

EDIT:

Rotel RB-1572:

http://img210.imageshack.us/img210/8171/dsc9593.jpg

http://img60.imageshack.us/img60/7590/dsc9592.jpg

http://img148.imageshack.us/img148/3734/dsc9596.jpg

As stated before, the RB-1572 is using two 500A modules + custom Rotel power supplies.

Rotel RMB-1575:

http://lh3.ggpht.com/_ZkDgli45Rys/SdniBFiNXUI/AAAAAAAAADQ/nzSaauVoPHg/s800/IMG_0191.JPG

http://lh6.ggpht.com/_ZkDgli45Rys/Sdnh8Qgv0JI/AAAAAAAAADM/xgvQCDwbUnY/s800/IMG_0189.JPG

Looks like two ICEpower500ASP modules (front left + front right channel) to me which power three additional ICEpower500A modules (according to the ICEpower website, the built-in power supply of each ASP series module can also power ICEpower A series amplifiers) that in turn power the center and the two surround channels.

[Carrotman]

What about the RB1562 vs RB1072, does the 1562 use older modules to like the 1572 compared to the 1072?

Based purely on the specs and the price, I would guess that the 1562 are using the same 200ASC's as the 1072 altough the input buffer may be different. The 1565 would then be a 200ASC/200AC-based design.

/U.

[Wolfenstein 2k2]

Picked up the brandnew RB-1092 today.

At home I unpacked the unit and put it into my rack. Then I made sure that all RCA and speaker cables were correctly connected. Finally, I attempted to plug in the included power cord and was very surprised. Why?

Well, I could not plug the end of the power cord into the AC connector on the back of the amp. At closer inspection I saw the problem. The amp`s AC connector had a third "pin" for ground connection! The power cord only had two "holes" such that it did not fit mechanically.

I was quite "pissed" at that moment - not because of the useless power cord that Rotel had included, but rather because I knew that in the past I`ve always had an audible ground loop problem (cable TV + higher current appliances with extra ground connection = humming / buzzing). For instance the RB-1080 and RB-1090 are grounded via the power cord and thus produced unmistakeably a humming / buzzing in my system. That is why I ultimately bought an RMB-1075 which is not grounded via the power cord.

Up to today I was absolutely convinced that the RB-1092 is NOT grounded via the power connector. Look here:

http://www.rotel.com/content/backpaneldrawings/rb1092-bk.pdf

http://www.florian-wopfner.com/pictures/homehifi/homehifi_91.jpg

http://www.hometheaterhifi.com/volume_14_1/images/rotel-rb-1092-amplifier-rear-panel.jpg

Obviously Rotel changed this issue over time, or maybe all European models need an extra grounding due to some restrictions / directives? The drawings in my RB-1092 manual clearly show that the AC connector has a third "pin", so this is different from the back panel drawing(s) provided by the international Rotel website.

Nevertheless, I powered up the amp using a PC power supply cord and guess what?!? No buzzing, no humming at all! What is going on here? I have no explanation for that. But believe me, I´m very glad to have no humming / buzzing at all, even if I crank up the volume to insane levels. Any ideas?

Maybe during the manufacturing process Rotel simply used parts that were currently available - in this case an AC connector with a third "pin" for grounding. Unfortunately I cannot see whether there actually is an electrical connection / wire / etc. going from the AC connector´s ground "pin" to another section of the amp...

[Carrotman]

The 1000ASP on which the 1092 is based normally requires an earth connection (at least in Europe, US regulations might be different) so I would expect the unit to have a 3-pin IEC with all three pins connected internally. However, I believe there is an on-board ground loop breaker circuit on the 1000ASP which may be why you are not having any problems.

/U.

EDIT: Any first impressions on the sound?

[Wolfenstein 2k2]

@ Carrotman

I just hooked-up my PC to the RSP-1098 and the humming / buzzing was back, however I had to crank up the volume to 50 and above to hear the humming / buzzing at my listening position. Hence the actual problem still exists.

Maybe your´re right and the RB-1092 has an onboard ground loop breaker circuitry. Anyway, all that matters to me is the fact that the RB-1092 is free from humming / buzzing despite the grounding.

Concerning the sound, I have to admit that the changes are not as obvious as expected. After two or three hours of listening to the same tracks I switched back to the RMB-1075. My current conclusion is that the RMB-1075 and the RB-1092 sound different, but I still need some time to find out what these differences are and to come to a final conclusion. As for the time being, the RB-1092 seems to have a tighter, more defined bass than the RB-1075 as well as a better resolution as for the mids and high frequencies. I don´t know yet how to describe my first overall impression, let´s say "fast" and "awesome timing"?

EDIT:
By the way, when I power up the RB-1092 I can hear a silent "plopp" coming from the speakers` woofers as well as a silent "hiss" from the tweeters the moment when the relays are clicking. I don´t even have to switch on the RSP-1098 for that. Nothing to be worried about I assume? I mean, the RMB-1075 does the same, but it´s almost inaudible.

[Carrotman]

@ Carrotman
I just hooked-up my PC to the RSP-1098 and the humming / buzzing was back although I had to crank up the volume to 50 and above to hear the humming / buzzing at my listening position. Hence the actual problem still exists.

PC power supplies are usually noisy and can have odd grounding, so if your source is a PC I am not surprised you may have experienced ground loops.

By the way, when I power up the RB-1092 I can hear a silent "plopp" coming from the speakers` woofers as well as a silent "hiss" from the tweeters the moment when the relays are clicking. I don´t even have to switch on the RSP-1098 for that. Nothing to be worried about I assume? I mean, the RMB-1075 does the same, but it´s almost inaudible.

That's perfectly normal (and perfectly harmless). In the class-AB amps there's probably a relay on the output to reduce the "thump" you get, but the ICEpower modules don't have that so it will be a little louder.


/U.

[Wolfenstein 2k2]

PC power supplies are usually noisy and can have odd grounding, so if your source is a PC I am not surprised you may have experienced ground loops.

Uups, in my previous post I wanted to say: "I just hooked-up my PC to the RSP-1098 and the humming / buzzing was audible, however I first had to crank up the volume to 50 and above to be able to hear the humming / buzzing at my listening position."

Anyways, no, my main source is a Pioneer DV-LX50 DVD/CD/SACD Player. I deliberately hooked-up the PC because I knew it would cause ground loops humming / buzzing.

As stated before, I experienced similar humming / buzzing when I tested the RB-1080 and RB-1090 some years ago. Does this mean that those amps probably have an odd grounding, too? Maybe the cable system in my home is (still) the real cause, but I had it checked some time ago, and the aerial wiring was properly grounded accoring to the repairman.

This is the RB-1572 without the top cover: http://img148.imageshack.us/img148/3734/dsc9596.jpg
As you can see, the grounding is nothing more than a single wire connected to the base plate. The same is true for the RB-1092.

That's perfectly normal (and perfectly harmless). In the class-AB amps there's probably a relay on the output to reduce the "thump" you get, but the ICEpower modules don't have that so it will be a little louder.
/U.

I have to correct my previous statement a little bit. When I press the power button on the RB-1092, you have to wait approximately 1 second until the relays are audible. Immediately afterwards this "thump" occurs. But if that's perfectly normal and perfectly harmless, I don´t care :T

[mjb]

This is the RB-1572 without the top cover: http://img148.imageshack.us/img148/3734/dsc9596.jpg
As you can see, the grounding is nothing more than a single wire connected to the base plate. The same is true for the RB-1092.

Which means the RCA (phono) input shields are therefore connected to your house ground, unless they're isolated from the case. If not, it probably also earths the rest of your equipment too, possibly creating a ground loop.

If the ground is just a single wire connected to the base plate, its a safety earth, and can be lifted if you're having ground loop problems.

[Wolfenstein 2k2]

Fortunately, I don´t have any ground loop problems with the RB-1092 against first expectations (*knock on wood*). However using an RB-1080 / RB-1090 in my system, or connecting the PC to the pre-amp creates an audible ground loop noise as stated before.

I´m not an electrician, so I´m asking again for clarification:

1) The grounding in the RB-1092 "merely" seems to be a safety earth. That is, the single wire going from the base plate to the AC connector on the back of the amp is physically connected to the grounding pins of my wall socket which in turn is connected to my house ground, right? Consequently, the amp´s case should be properly earthed right now.

2) In case my assumptions made in 1) are correct + the fact that I do not experience any hum / buzz suggests that the RCA inputs must be isolated somehow from the case, or not?

Anyways, all that counts is the absence of ground loop hum / buzz ;x(

EDIT:
To come back to the sound of the RB-1092 vs. the RMB-1075:

I´ve spent the whole day listening to some of my favorite tracks and switching forth and back between those two amps. First of all, both my friend and I came to the conclusion that the RB-1092 has softer highs and more detailed mids and highs. I prefer this softness in the upper frequency band since my tweeters in combination with the RMB-1075 occasionally show a certain tendency of "hissing" , especially as to the reproduction of voices when there´s a word beginning with "s", "sh", "ch", or "z". All in all, the RB-1092 thus sounds more pleasant in my ears. Concerning the increased level of detail in the mids and higher frequencies, well, I welcome this improvement as well. I´m not sure yet what to say about the lower end of the frequency band...still need some time...and it´s Sunday, cannot crank up the volume to extreme levels :W

[mjb]

I´m not an electrician, so I´m asking again for clarification:

1) Correct
2) Not necessarily, you'd have to check with an ohm meter.

Anyways, all that counts is the absence of ground loop hum / buzz ;x(

Yes, be happy :T

[SkyDover]

I own alot of different kind of amps. In the past 3 homes I have lived in, I get a bit of hum in all my analog amps. My digital amps are silent and my class D amps are near silent. I own a Rotel RB-1090 and RC-1090 and have always had a slight hum to them and I blamed it on Rotel. It wasn't until this year when I moved into a new home that has a home theater room that has a dedicated outlet that is shared with nothing else, for the first time I've heard how silent the Rotel RB-1090 and RC-1090 can be. So now I know it wasn't Rotel's fault.... it was the homes ground-loop problem but I was told I had no ground loop problem but the dedicated outlet solved the hum problem! If I plug the amp into another outlet in the house, the hum is back. It is only silent in the dedicated outlet. Just a lesson that I learned.... that is isn't Rotel's fault for the hum.

[Wolfenstein 2k2]

I don´t blame Rotel either, according to the cable guy it´s rather a matter of different grounding potentials (house grounding vs. grounding of the cable TV wiring) or something.

Both the RB-1080 and RB-1090 were perfectly silent and did not cause any 50-60Hz (AC) humm / buzz in my speakers and subwoofer when I pulled out the coaxial TV cable from the wall socket (the coaxial cable goes into the DVB-C receiver which in turn is connected to my preamp thus causing humm / buzz). I´m really happy that the RB-1092 has not caused any problems (yet).

[SkyDover]

It would be very interesting to me to hear the differences from the RB-1092 and RB-1572. I had the RB-1092 and have a RB-1090 and after listening to them side by side, I quickly realized I preferred the RB-1090 with it's fuller, rounded, and smoother sound. It just sounded better to me overall. The RB-1092 sounded flatter and more horizontal to me without the rounder fuller sound..... I guess they may call that the airiness? Have Rotel really changed the RB-1572 to sound more rounded and fuller than the RB-1092? Does it get near the sound of the RB-1090 now?

[wettou]

It would be very interesting to me to hear the differences from the RB-1092 and RB-1572. I had the RB-1092 and have a RB-1090 and after listening to them side by side, I quickly realized I preferred the RB-1090 with it's fuller, rounded, and smoother sound. It just sounded better to me overall. The RB-1092 sounded flatter and more horizontal to me without the rounder fuller sound..... I guess they may call that the airiness? Have Rotel really changed the RB-1572 to sound more rounded and fuller than the RB-1092? Does it get near the sound of the RB-1090 now?

Class D vs Class A/B?

Class A/B will always sound better ....

[SkyDover]

Yes, Class D vs Class A/B.

Ok, then nothings changed. I found the RB-1090 (Class A/B) to be better than my RB-1092 (Class D). Just was curios if Rotel had things different with the RB-1572 by chance.

Wow, I see Rotel has really upped the price of the RB-1080 from $1000.00 to $1500.00 with the RB-1582 which is all RB-1080 inside just a new silver case. That's quite a jump in price!! I'm shocked!

[Wolfenstein 2k2]

Interesting, 1000$? Here in Germany the RB-1582 (MSRP 1349 Euros incl. 19% VAT) has actually become cheaper than the older RB-1080 (MSRP 1579 Euros incl. 19% VAT). Yep, Europe - the world´s cash cow, but that´s another story...

[eelco74]

Yes, Class D vs Class A/B.

Ok, then nothings changed. I found the RB-1090 (Class A/B) to be better than my RB-1092 (Class D). Just was curios if Rotel had things different with the RB-1572 by chance.

Wow, I see Rotel has really upped the price of the RB-1080 from $1000.00 to $1500.00 with the RB-1582 which is all RB-1080 inside just a new silver case. That's quite a jump in price!! I'm shocked!

The 1582 is no where near the 1080 as far as design. The 1080 had severval revisions, version 4 beiing te latest. So you cannot compare just any 1080 with the 1582.

The 1582 is different in selected components, however the setup and design is based around the 991/1080 design.

[mjb]

Yep, Europe - the world´s cash cow, but that´s another story...

lol, sad isn't it. A CA-2200 costs about 8.5K USD in Germany, so a RB-1582 is quite a bargin ;-)

[Wolfenstein 2k2]

I´ve never had the chance to get my hands on those two amps. Whether the CA-2200 is worth the extra charge over the RB-1582 or RB-1092, well, it depends on many things, I guess...

[SkyDover]

>The 1582 is no where near the 1080 as far as design.

I looked at pictures of a guy who has the RB-1080 and RB-1582 and he says they are practically identical. I remember looking at the pictures...... they sure look near identical to me! Here's a picture of the RB-1080 and RB-1582. I'll let you decide for yourself, but sure looks more alike in design than not, near identical.....if you don't mind me saying so! Sorry.

Ok..... let me see if I can figure out how to upload the pictures now......

[SkyDover]

RB-1080

RB-1582

[SkyDover]

I'm aware Rotel had revisions for the RB-1080 and RB-1090. Most were revisions to solve the blowing fuse problems some people had. Luckily I didn't get any of those versions, mine are the latest versions. The RB-1582 is more like the latest version RB-1080.

[SkyDover]

>19% VAT). Yep, Europe - the world´s cash cow, but that´s another story...

Wow, and I thought ours were bad here......you're 10% more, but the way politicians are going at it here......they are trying to change it like there! They're all just a bunch of cash cows! Sad!

[SkyDover]

Ok, I just got off the phone with my Rotel Dealer, he said there is no benefit going from a Rotel RB-1080 to RB-1582 because sound is the same and basically the same inside but that the RB-1582 does not have balanced inputs, where as the RB-1080 does have balanced inputs. He says it's no new design but heavily based on the RB-1080 which has always been a great seller for Rotel. Just wanted to let you know what he said.

[Wolfenstein 2k2]

>19% VAT). Yep, Europe - the world´s cash cow, but that´s another story...

Wow, and I thought ours were bad here......you're 10% more, but the way politicians are going at it here......they are trying to change it like there! They're all just a bunch of cash cows! Sad!

Don´t get me wrong, I´m not really complaining about the 19% VAT here in Germany. As compared with other European countries, 19% VAT is even slightly below average: http://www.evz.de/UNIQ126782826929543/doc424A.html

I was rather indirectly complaining about the fact that for some time past Dollars are almost always converted into Euros one-on-one - independent of the current exchange rate.

Moreover, I mentioned the VAT because all manufacturer's suggested retail prices in Germany have to include VAT which is different in other countries.

Off-topic off

[ronning]

Based purely on the specs and the price, I would guess that the 1562 are using the same 200ASC's as the 1072 altough the input buffer may be different. The 1565 would then be a 200ASC/200AC-based design.

/U.

I just peeked inside a 1562 and a 1565 recently (it's really hard to see through all the caging on the 1562) but can confirm that BOTH these units are using the 200AC modules. I think (but can't confirm) that the 1565 is using the ASC (with built in power supply) for the fronts, and AC in line for the rears/center.

However, the 1562 is using a custom power supply that appears to be created by Rotel (the 1562 is using the "unpowered" 200AC modules).

Actually, today I'm A/B testing the 1562 to the 1572. The 1562 really sucked at first, but i think i reversed polarity. It's really starting to sing now (or maybe it was break-in?)

Anyway, I'd love to keep the 1572 but it's picking all kinds of noise and hum from my home theater PC (the '72 has a grounded 3-prong plug). So that's out of my options for the moment (at least until I figure out how to clean up the ground noise - and I'm already using a high end power filter/conditioner)

The '72 is definitely fuller/fatter/warmer than the '62. However, the '62 is very detailed and nice. But not good enough for me to buy it. I was REALLY hoping the '62 would be great, then i could buy the 1565 but it appears to not be that way.

My understanding is that the "AC" series of ICE modules are far inferior to the "A" or "ASP" series. For example, the older 1077 which garnered rave reviews used the 250ASP. Whereas these newer, cheaper 100w amps are the "AC" models and probably not as good as the older 1077 (although the 1077 doesn't benefit from a custom Rotel power supply).

At least, that's where my thinking is at today.. (trying to figure it all out!)

[Carrotman]

My understanding is that the "AC" series of ICE modules are far inferior to the "A" or "ASP" series. For example, the older 1077 which garnered rave reviews used the 250ASP. Whereas these newer, cheaper 100w amps are the "AC" models and probably not as good as the older 1077 (although the 1077 doesn't benefit from a custom Rotel power supply).

Well, the AC/ASC's are cheaper than the others, which alone is enough to equal "inferior" for some people. If at all possible, try listening to the amps instead of just relying on the (more or less) "informed" opinion of others.

As I think I have mentioned earlier, I generally prefer the sound of the 500ASP-module to that of the 1000ASP. However, as I am now using "bright" speakers (Elac), I have actually switched to 200ASC-based amplifiers because their slightly darker signature compliments the bright speakers. So, while I have technically been "downgrading" all along, the smile on my face when I listen to my system has been getting steadily wider :B


/U.

EDIT: So, long story short - "different" isn't necessary = "inferior".

[n visser]

Hi
Yes there are some sounds differents from the RB1092 to the RB1572. The 1092 has a more cold/controlled sound a little thin/hard in sound and the 1572 has a more warm/naturel sound. And I must say that I was blow away by the sound of the RB1572, it is that good. I myself did an AB test between the two amps today, because i wanted to hear the difference from the old ICEPower to the new modules.

But go and have a listen your self.

Hi guys my name is Noel i just joined the club.

Reading the post above was something i accidentily came across
while looking for fuse problems with my rb 1080.

I read the story about cold/controlled and warmer sounds from the amps
you mentioned.

While experimenting with my amp something got my attention.

With the new fuses i placed T 6.3 a/250v Conquer ute fuses. (Normal glas tube fuses)

The rb 1080 almost sounds exactly the same as his younger brother the rb 1582.

the sound was still very controlled but somehow softer/easyer with friendy trebles with full and a warmer bass.

Experimenting with other glas tubed fuses also 6,3 a /250v fuses.

Just the same but lac fuses instead of ute fuses with nickel caps and a copper wire somehow freshed up the amp.

More detail at all frequenties but with a fresher/and comforting sound not colder in any way.

Experimenting with fuses can tweak your system just so that it works.

Thats what i experienced a fuse can do the trick instead of a new amp.

Hope this was helpful to you guys.

Greetings.

Noël.