Rotel 1520 amp enough to drive 2 pairs of speakers B&W CM9s & B&W CM5s?

[brody]

I purchased a Rotel 1520 integrated amp. I'm using it to drive 2 pair of speakers - B&W CM9's & B&W CM5's. Twice now it has gone into protection mode when playing at about the 10:30 position on the volume control. The dealer claims the amp is more than adequate. I am beginning to question this.
What are your thoughts on this?

Thank you.

[stuofsci02]

Yeah.. I am not surprised that this happened. When you run A/B speakers at the same time, for the amp it looks like it is running a single pair of speakers with half the impedance. So your 8 ohm speakers now look like a pair of 4 ohm speakers to the amp..

To further complicate matters, at some frequencies the CM9s are rated at 3 ohms and the CM5's are rated 3.7 ohms.... So to the amp these will look like a pair of 1.7 ohm speakers at those frequencies..

This would make a lot of amps unstable, especially as volumes go up.. Since this amps power is not huge I am not surprised it faulted...

[brody]

Would a rotel rb-1552 or rb-1562 be an appropriate amp for the speakers

Ok. I listened to the dealer and he said the integrated amp was plenty powerful enough to drive the 2 pair of speakers (which I figured would be correct since B&W and Rotel are apparently owned by the same parent company). I figured any Rotel amp should be able to drive the B&Ws since both speakers supposedly only needed 40 watts minimum.

The 1552 & 1562 amps are rated at 120 and 100 watts respectively. The 1562 is a class D amp which supposedly runs cooler and delivers 200 watts at 4 ohms. The Rotel site does not specifiy the 1552 amps 4 ohm rating. Will, either of the amps have plenty of power to drive both pairs of B&Ws simultaneously? If so, which amp is the better choice? After reading info on the Magneplanar website, Magneplanar does NOT appear to be a fan of the class D amps.

Thanks for your advice.

[stuofsci02]

Last I heard Rotel is now pushing it's class D amps only towards HT use. Assuming music is your priority I would stick to the A/B amps.

Driving two speakers at the same time really is hell for an amp. While this amp might be able to do it with two pairs of B&W 686 (which have 5.1 ohm min impedance) to a higher volume, at some point the power runs out.

Hypothetically speaking, if you are running into 4 ohms, you are asking the amp to provide twice the amperage/current at the same power level. If you are at those minimum impedance frequencies (which are typically lower frequencies) then the amp might need to put out 4+ times the amount of current it would into an 8 ohm load..

The only way to do it is if the volume is low, because it runs out of juice one you ask for more...

I do not believe you have an equipment problem. I think the amp cannot run those two pairs of speakers at the same time with the volume level you want..

[madmac]

Rotel's do not like 4 ohm loads and they are not recommended for those loads either. They like nice generic 8 ohm loads!!. Although, I am surprised that it's pooping out at 10:30 volume setting. Like mentioned above, you must be going even lower than 4 ohms on occasion which the Rotel will most certainly complain about!!!.

[stuofsci02]

brody,

Is this a new integrated? Could you return it for something else?

[Mikael]

You are wrong Madmac
Rotels do work fine with loads down to 4 ohms, infact it is one of very few not very high end brands, that has a perfect power measuring cube stable down 3 or so ohms.

In other words Rotel can handle B&W speakers very well, and they can go as low as 3,2 ohms. In the smaller Rotel amps like the intergrated 1520 the bass of the speaker will not have the same full body sound as if you use the RB 1552 or RB 1582.

If Rotel amps has a problem with B&W speakers I would say it has to be in the treble end of the frequency some of the Rotel amps can sound a bit bright with B&W speakers.

Just my 2 cents

[stuofsci02]

You are wrong Madmac
Rotels do work fine with loads down to 4 ohms, infact it is one of very few not very high end brands, that has a perfect power measuring cube stable down 3 or so ohms.

In other words Rotel can handle B&W speakers very well, and they can go as low as 3,2 ohms. In the smaller Rotel amps like the intergrated 1520 the bass of the speaker will not have the same full body sound as if you use the RB 1552 or RB 1582.

If Rotel amps has a problem with B&W speakers I would say it has to be in the treble end of the frequency some of the Rotel amps can sound a bit bright with B&W speakers.

Just my 2 cents

Yes, but what is your take trying to run two fairly difficult loads of off one little RA-1520...

[brody]

customer support says to hook an rb 1552 into the ra 1520

Rotel support guy said to get a 120 watt 1552 amp, plug that amp into the 60 watt 1520's preouts, hook the CM9's into the 1552, the CM5's into the 1520.
He thinks even the 1552 isn't enough to adequately drive both pairs of speakers.
My concern on this setup is - won't the CM9's be considerably louder than the CM5's since I'd be using the 1520 as the preamp for both?

I would expect a 120 watt rotel amp to be considerably louder than a 60 watt rotel amp at the same volumne position...

Customer support person said his rule is take the max wattage a speaker can accept and give it an amp with at least 1/2 that wattage.

CM9's max is 200 watts => 100 watt minimum amp
CM5's max is 120 watts => 60 watt minimum amp
That's why he's saying the 120 watt rotel 1552 is not enough to drive both pair.

WOW...

[stuofsci02]

Rotel support guy said to get a 120 watt 1552 amp, plug that amp into the 60 watt 1520's preouts, hook the CM9's into the 1552, the CM5's into the 1520.
He thinks even the 1552 isn't enough to adequately drive both pairs of speakers.
My concern on this setup is - won't the CM9's be considerably louder than the CM5's since I'd be using the 1520 as the preamp for both?

No.. As long as the gain of the 1552 is the same as the 1520's amp stage then it will be the same as it is now.. Right now you will have a small amount of volume difference because of the different sensitivities of the speakers.. Probably not really noticeable.. Especially if the speakers are in different rooms..

Just because an amp is more power it does not mean the speakers will automatically be louder.. It just means you will have the ability to go louder with the bigger amp without clipping the amp (going into protection mode).

[stuofsci02]

Customer support person said his rule is take the max wattage a speaker can accept and give it an amp with at least 1/2 that wattage.

CM9's max is 200 watts => 100 watt minimum amp
CM5's max is 120 watts => 60 watt minimum amp
That's why he's saying the 120 watt rotel 1552 is not enough to drive both pair.
WOW...

There is no hard and fast rule for this.. A lot of people like amps that have a higher output rating then their speakers can handle..

Speakers are rarely damaged because of over power. More frequently they are damaged from under power.. That is because when an amp runs out of steam it starts to clip and make strange distortions the speakers don't like...

So by having a bigger amp then your speakers can handle will mean you should never clip the speakers... The drivers will cook before the amp clips and you will notice the speakers are unhappy long before this happens.

[brody]

So would you agree with the customer support suggestion that the 120 watt amp by itself is NOT enough to power both the CM9's & CM5's in unison?

I could also try to get the sales guy to take back the 1520 (i'm guessing it's gonna cost me something) and go with the 120 watt amp and an associated preamp

or

the full 200 watt rotel rb 1582 and an associated preamp

[stuofsci02]

So would you agree with the customer support suggestion that the 120 watt amp by itself is NOT enough to power both the CM9's & CM5's in unison?

I could also try to get the sales guy to take back the 1520 (i'm guessing it's gonna cost me something) and go with the 120 watt amp and an associated preamp

or

the full 200 watt rotel rb 1582 and an associated preamp

I can't really say about the 120 watt being enough, because I don't know how loud you want to run these speakers at the same time.

In general I think you will be very safe adding on the 100 watt power amp.

Your other option is to go for a more powerful integrated amp from another manufacturer that is rated for low impedance..

[Mikael]

Hi stuofsci02

My take on your problem is this: Return your RA 1520 and get an RC 1550 and 2 RB 1552, one amp pr. speaker set, this would be the best way to go for you. The RC 1550 has 2 sets of preouts so it would be the way to go.

Why do you want it to drive to sets of speakers?

And Again I haven't heard of any power amp that is happy of driving 2 sets of speakers with different loads, and even not 2 with the same load.

[brody]

Interesting thought Mikael. Obviously I'm not an audiophile - this is by far and away the best system I've ever owned. The reason for the 2 sets of speakers is a have one rather large area to cover - kitchen, dining, living (no walls between the areas). The area is approx 40' X 22'. The CM5s are on top the kitchen cabinets, the CM9s are on the opposite side of the room on the floor. I simply figured since the amp has outputs for 2 pair of speakers, it could handle it. The sales guy said it could, but now he's wavering after I tell him what you guys and BW/Rotel support say.

I'm starting to learn a lot here and from BW support. Obviously I need more power, now the question is which way to go:

Hook a 1552 into the 1520, let the 1552 drive the CM9s, the 1520 drive the CM5s

or

Get a 200 watt 1582 with a 1550 or 1580 preamp and let it drive both pair

or

Take your suggestion (2 1552 amps / 1 1550 preamp) ie: 1 amp for each pair of speakers.

[Mikael]

Hi

You could keep the RA 1520 and use the knop on the front and choose the a speaker and just drive the set of speakers you connect to the the a speaker on the the back, say the cm 5 in the kitchen, and the cm 9 in the main room on the b speaker, and turn the knop on the front to only B speaker and just listen to cm 9 in the main room.
That way you will keep the load down to a acceptable level for the amp, but again if you want to play loud in that big a room, I would go with one RC 1550 and two power amps(RB 1552 or RB 1582)

If you go with the one RB 1582 and RC 1580 you will still get the though loads around 1.7 ohms, the RB 1582 will have more power tha the RA 1520 and RB 1552, but it's not recommended.

[stuofsci02]

Brody,

Since you already have an RA-1520, I think the idea of adding the external 1552 is a good idea.. Just check and make sure that the 1520 alone is enough for your CM5. I think it probably is, but it never hurts to check.

If the cost is too high to add on the other amp and the 1520 can go back to the store, there are other integrateds on the market that would be able to handle your needs in a single box (like what you are trying to do with your RA-1520).

[brody]

ok guys, thanks for all your help on this. bw/rotel support pretty much agrees with you guys - either the
1520 -> CM5, 1552-> CM9
OR
2 1552s (1 for each pair) with a 1550 preamp OR
250 Watt class D 1572 which can drive BOTH pair (new option).

The guy says the class D's bass would be tighter & quicker, but more up in your chest rather than floor pounding. He did say it will deliver 500 watts at 4 ohms which could overpower the speakers.

Any thoughts on that class D amp (good idea or bad)? I will make a decision after your input... Thanks again for all your help on this.

He said don't try the 200 watt 1582 to drive both pair of speakers, only the class D would be the way to go if i want to power 2 pair with 1 rotel amp

[stuofsci02]

I auditioned a RB-1572 Class-D a couple of year back when I was looking for an amp.. I did not much care for it to be honest. I also had a RMB-1565 as a loaner for a couple of months in October of 2011, and again it wasn't my cup of tea..

But as always your mileage will vary..

[brody]

the sales guy has been pretty cool and said he'd refund the purchase price of the 1052 if i wanted to swap it completely out (even though i don't have the box and it's 2 months old). tonight i will run the cm5s hard by themselves driven by the 1052. if it seems capable of running for several hours hard, i'll simply buy the 120watt 1552 and run the cm9s off it, the cm5s off the 1052, and use the 1052 as the preamp for both. it seems like everyone thinks the 1052 is easily capable of driving the cm5s solo.

thanks again!

[brody]

I am sending the 1052 integrated back - dealer will refund full price. Getting seperates - the 1550 pre and 1552 amp. Will try running both pair of speakers off the 1 amp and if i notice a sound degredation when running both pair vs just the CM9s solo on the amp, I will purchase a 2nd 1552 amp for the system.

[stuofsci02]

I am sending the 1052 integrated back - dealer will refund full price. Getting seperates - the 1550 pre and 1552 amp. Will try running both pair of speakers off the 1 amp and if i notice a sound degredation when running both pair vs just the CM9s solo on the amp, I will purchase a 2nd 1552 amp for the system.

Also a good idea...

[brody]

Basically given to me by you guys. Thanks again for all your help on this. I can see now the 1052 was no way capable enough of powering those CM9s.

[brody]

Just hooked up the 1552 and 1550 to the CM9s. OMG! What a difference. These things sound awesome now. Will bring the CM5s into the system on the same amp soon and see if CM9 performance goes down. If so, will get that 2nd 1552...

[Mikael]

that is good news.
I know the sound of the Rotel's and the sound of the CM9's, but not put together, where I live we can't hear Rotel and B&W at the same stores.
Could you try to describe the sound this combo makes?(warm, thin, full body bass, in your face treble and midrange or???)

Mikael

[brody]

I'll give the CM9s on the Rotel 1552 a much longer listen this Friday and try and decribe the sound the best I can. I can tell you way more bass, way fuller, lush sound for sure than when running the CM9s on the Rotel 1052 integrated. The difference was IMMEDIATELY noticable. So far I have listened only to Santana, Sade, and America on the 1552 (was looking for songs with nice bass, guitars, piano mainly during initial testing).

I also have a NAD 356 integrated (80 watts) that I compared against the Rotel 1052 integrated (60 watts). In my opinion, the Rotel clearly sounded better than the NAD running the CM9s. The NAD was REALLY harsh on some songs - Bob Seger (horizontal bop), Stones (respectable) for example. I had the NAD 1st and when I found it very harsh on some rock, that's when I decided to demo it against the Rotel 1052.

I have heard others say the same when comparing NAD vs Rotel running B&W speakers. As for how these amps sound driving other speakers, that may not be the case (the NAD may pair better with others).

[brody]

Again, I'm not an audiophile but I think the Rotel 1552 amp does an excellent job driving the CM9s. The amp has lots of punch. As mentioned before, I noticed a definite sound improvement over the Rotel 1520 integrated, which I though sounded very nice, but have since learned simply doesn't not have the power to properly drive the CM9s, let alone them paired with the CM5s. The 1552/CM9 combo has very deep, quick, and well defined bass without being overpowering. All instruments come through very clearly. Rather than warm, I would call it crisp (perhaps slightly bright) on the CM9s. Its has lots of punch. If there were an area I would tone down slightly it would be the midrange (but this is rather nit-picky and the amp has not been through it's burn in period). I'm very happy with the purchase and feel it's the right amp (considering price of course) for the CM9s. Pretty sure I will purchase a 2nd Rotel 1552 in order to drive the CM5s on a seperate amp. I see your guys' point now.

As an FYI in case anyone else may be interested:
The amps I considered originally were all integrated: Marantz PM8004, Nad 356, and Rotel 1520. I bought the Rotel because I thought it was the best all around performer of the three. The Marantz was nice (warmest), but least powerful and I felt lacked a little punch. The Nad was simply too harsh sounding but had lots of punch. The Rotel's punch was comparable to the Nad.

I would have gone 1. Rotel, 2. Marantz, 3. Nad.
The Rotel 1552 clearly smokes all three, as it should.

[Venom]

Hi guys,

I have a similar issue but driving a pair of B&W cm9s only, Amp is 2 months old and sitting on top of my Tv unit. Air circulation is not restricted.

Found that the problem is temperature related. As you can see on the video below volume knob is less then half.

Room temp is around 27 C degrees. Just to confirm that this is temperature related used a fan and plays for hours with no problems.

In your experience, Is this normal or should I start calling the shop for an RMA? I don't want to have a fan next to it running!

Cheers,

[madmac]

Again, I'm not an audiophile but I think the Rotel 1552 amp does an excellent job driving the CM9s. The amp has lots of punch. As mentioned before, I noticed a definite sound improvement over the Rotel 1520 integrated, which I though sounded very nice, but have since learned simply doesn't not have the power to properly drive the CM9s, let alone them paired with the CM5s. The 1552/CM9 combo has very deep, quick, and well defined bass without being overpowering. All instruments come through very clearly. Rather than warm, I would call it crisp (perhaps slightly bright) on the CM9s. Its has lots of punch. If there were an area I would tone down slightly it would be the midrange (but this is rather nit-picky and the amp has not been through it's burn in period). I'm very happy with the purchase and feel it's the right amp (considering price of course) for the CM9s. Pretty sure I will purchase a 2nd Rotel 1552 in order to drive the CM5s on a seperate amp. I see your guys' point now.

As an FYI in case anyone else may be interested:
The amps I considered originally were all integrated: Marantz PM8004, Nad 356, and Rotel 1520. I bought the Rotel because I thought it was the best all around performer of the three. The Marantz was nice (warmest), but least powerful and I felt lacked a little punch. The Nad was simply too harsh sounding but had lots of punch. The Rotel's punch was comparable to the Nad.

I would have gone 1. Rotel, 2. Marantz, 3. Nad.
The Rotel 1552 clearly smokes all three, as it should.

Nothing you've said here surprises me at all. The Rotel should 'smoke' all the amps listed here. Enjoy !!