Rotel integrated amp “house sound”?

[Ramsay]

I am returning to the stereo/hi fi world after a considerable period of Bluetooth streaming to Sonos speakers. In assembling my components, I am considering Rotel integrated amps, in particular the A12 MKII or A14 MKII. I have done research, listened to YouTube reviews, etc.A recent review I heard made the statement that Rotel has changed/improved the “house sound” of their amps with the MKIi series. Can someone help me understand what the Rotel house sound was with the previous model amps and what the differences are with the MKII series? Thank-you

 

[NiagaraPete]

Amps should be transparent. Any hint of "house sound" should be a red flag.

Budget? What are you planning to use as speakers? Speakers are where you should start not amps.

 

[REK2575]

I am returning to the stereo/hi fi world after a considerable period of Bluetooth streaming to Sonos speakers. In assembling my components, I am considering Rotel integrated amps, in particular the A12 MKII or A14 MKII. I have done research, listened to YouTube reviews, etc.A recent review I heard made the statement that Rotel has changed/improved the “house sound” of their amps with the MKIi series. Can someone help me understand what the Rotel house sound was with the previous model amps and what the differences are with the MKII series? Thank-you

I recently purchased the Rotel RC-1572 mkii preamp and RB-1552 mkii power amp, replacing a Denon AVR I've used for over 20 years. I'll be d*%!*d if I can hear anything I'd characterize as a distinct 'sound.' Nor is that my aim -- I want as transparent as possible, and I feel that's what the Rotel components are delivering.

If you want transparent, you can purchase the Rotel amps with peace of mind.

 

[MarkS]

A recent review I heard made the statement that Rotel has changed/improved the “house sound” of their amps with the MKIi series. Can someone help me understand what the Rotel house sound was with the previous model amps and what the differences are with the MKII series? Thank-you

Pure placebo effect in the mind of the "reviewer".

 

[airgas1998]

I am returning to the stereo/hi fi world after a considerable period of Bluetooth streaming to Sonos speakers. In assembling my components, I am considering Rotel integrated amps, in particular the A12 MKII or A14 MKII. I have done research, listened to YouTube reviews, etc.A recent review I heard made the statement that Rotel has changed/improved the “house sound” of their amps with the MKIi series. Can someone help me understand what the Rotel house sound was with the previous model amps and what the differences are with the MKII series? Thank-you

sorry man wherever you heard of this "house sound" from is a bafoon...

 

[Ramsay]

Intuitively, it didn't make sense that different amps would make the same speakers sound differently, but many of the so-called expert reviewers will say that brand X amps produce a warmer sound and are better for a certain type speaker and brand Y amps produce a different sound and are best paired with a speaker with similar sound characteristics. Are you saying that sound measurements simply don't substantiate this?

 

[MaxBuck]

Intuitively, it didn't make sense that different amps would make the same speakers sound differently, but many of the so-called expert reviewers will say that brand X amps produce a warmer sound and are better for a certain type speaker and brand Y amps produce a different sound and are best paired with a speaker with similar sound characteristics. Are you saying that sound measurements simply don't substantiate this?

What do you claim these "so-called expert reviewers" to be expert in, aside from self-promotion?

 

[BDWoody]

...so-called expert reviewers will say that brand X amps produce a warmer sound...

When any of them can demonstrate this while doing the listening with some basic controls (starting with no peeking to know what's playing), that might be worth something.

Here is a video done by our host that goes into this a little bit.

 

[MarkS]

Intuitively, it didn't make sense that different amps would make the same speakers sound differently, but many of the so-called expert reviewers will say that brand X amps produce a warmer sound and are better for a certain type speaker and brand Y amps produce a different sound and are best paired with a speaker with similar sound characteristics. Are you saying that sound measurements simply don't substantiate this?

Correct. Not only measurements, but also properly controlled listening tests.

 

[restorer-john]

Rotel have always had a 'house sound'. From day one in the 1970s.

Their amplifiers (and preamplifiers) roll off in the bottom octaves and also tend to be bandwidth limited somewhat in the top octaves. They are not, nor ever have been, DC- daylight response designs. It is deliberate.

 

[polmuaddib]

Rotel have always had a 'house sound'. From day one in the 1970s.

Their amplifiers (and preamplifiers) roll off in the bottom octaves and also tend to be bandwidth limited somewhat in the top octaves. They are not, nor ever have been, DC- daylight response designs. It is deliberate.

Really?
With such a flat audioband response, it is no surprise that a 1kHz squarewave was reproduced with an excellently square shape - said John Atkinson in Stereophile review of Rotel RB 1080.
And just to check, I looked at several FR graphs of different power amps on Stereophile for comparison and they all look very similar.
Some amps, including Rotel, do exhibit couple of dBs roll off below 20hz, but are all fully flat from 20hz to 20khz.
How many passive speakers exist that are flat 0db down to 15hz that would suffer audibly form this slight roll off?

 

[HarmonicTHD]

Keep your options open and don’t set your sights on a particular brand. Rather see where independently verified measurements exist (see amp review table here in the forum) and start by looking at the top ten to top 20 and see which ones meet your other requirements eg power, convenience features, budget or even optics.

The Rotel, even according to the manufacturer data (0.018% THD ca 74dB) is about a factor 10 to 100 off by what is nowadays considered state of the art amp engineering. Even the jack of all trades AVRs nowadays deliver solid THD+N in the 90ties to 100redth dB.
This link gives a good perspective what these measures mean, what is possible and what is audible.

Audibility thresholds of amp and DAC measurements

Introduction A recurring theme on ASR is whether or not the various measured qualities of the devices are audible. In this post, I'll present some clear and visual thresholds for when those imperfections can be considered a potentially audible concern. I will not explain the basics of amp/DAC...

www.audiosciencereview.com

Also remember spent 90% or more on speakers and Room EQ. Amps and DAC are among the least contributing components to sound quality (against often other common but erroneous belief).

 

[restorer-john]

With such a flat audioband response, it is no surprise that a 1kHz squarewave was reproduced with an excellently square shape - said John Atkinson in Stereophile review of Rotel RB 1080.
And just to check, I looked at several FR graphs of different power amps on Stereophile for comparison and they all look very similar.
Some amps, including Rotel, do exhibit couple of dBs roll off below 20hz, but are all fully flat from 20hz to 20khz.
How many passive speakers exist that are flat 0db down to 15hz that would suffer audibly form this slight roll off?

A 1kHz square at very low amplitude (as JA does) shows little about the low end. A 100Hz square will.

All the Rotels I have (probably about 6 or 8 of various vintages) plus every Rotel I've ever worked on, have (some would say sensibly) agressive LF roll-offs.

Just peruse any random Rotel schematic, do the math, calculate the F3s on the coupling RCs and the NFB loop RC values.

But to the funny part of the review you quoted, where JA blew the amplifier up on a 2R load. He says this:

"The Rotel has sophisticated output protection, in addition to 6.3A fuses in the positive and negative voltage rails for each channel. Nevertheless, during the high-power testing, I blew the rail fuses when I was testing the amplifier's continuous output into 2 ohms. Even after I'd replaced these fuses, the amplifier would not turn on again—even after I'd let it cool down and had reset it with the front-panel Power button."

When he tested the RB-1080 in 2002, it only had 6.3A fuses and nothing to prevent overcurrent, overdrive, DC etc. Hardly sophisticated. The unit has a simple turn on delay/thermal function which merely shorts the inputs.

Here is the October 2007 revision where they upgraded the fuses to 8A, but still no sophisticated protection...

Finally in the revision 5 of the RB-1080, in January 2008, 6 years after JA reviewed it, it gets some form of semi 'sophisticated' protection in the form of the ubiquitous UPC-1237HA protector IC and output relay. This IC can sense overcurrent, DC, short circuit, overdrive etc.

Bottom line? Don't listen to a thing reviewers say because, mostly they are regurgitating company provided BS.

And Rotel is a stand up company. Their product has always been decent, good value and solid as a rock.

 

[polmuaddib]

I have no technical knowledge to compare circuits and I believe that Rotels are not SOTA amps. Very scary fact about protection circuit you showed, John. Or lack of…
But, can you show some graphs where there is a low end roll off?
I have not seen any major FR issues in amps Amir tested, if I remember right. Maybe some.

 

[Vacceo]

Intuitively, it didn't make sense that different amps would make the same speakers sound differently, but many of the so-called expert reviewers will say that brand X amps produce a warmer sound and are better for a certain type speaker and brand Y amps produce a different sound and are best paired with a speaker with similar sound characteristics. Are you saying that sound measurements simply don't substantiate this?

Those claimed changes in sound are quite, quite easy to point out on a test bench: does the amp alteer any frequency? If so, what frequency does it change?

That aside, electronics generate noise (it can be measured; if the device is well-designed, it will be low and not audible) and harmonic distortion (that again, should be so low that could only be noticed at intolerable volume levels, so you´d need measuring devices to notice it).

It is super easy for a specialist to test these elements with the right equipment. If the changes can be noticed "by ear", the amp is a complete dissaster.

 

[billyjoebob]

Loved my Rotel amp. Still have it.
Just not in service at the moment.
Be careful what advice you recieve and do your homework.
Those (especially older) amps absolutely sound different than some of the modern sterile amps.
And this is coming from a current Marantz user.

 

[restorer-john]

But, can you show some graphs where there is a low end roll off?

I am talking about Rotel's design philosphy from the 70s onwards. They continue, to this day of following a bandwidth limited design in all but their most expensive power amplifiers, where, even then, they are not as ruler flat as other designers choose to be.

Their 'giant-killing' UK favourite integrated amplifiers are almost always lacking in the deep bass and rolled-off in the lowest octaves. I do have a quite a few Rotel integrated and power amps here, and even a relatively recent silver A-something in a box I could pull out and test. Put it this way, I love their gear, and even use a classic 90s RA-930ax for TV duty but they aren't ruler flat or accurate pieces of gear.

 

[Ageve]

They continue, to this day of following a bandwidth limited design in all but their most expensive power amplifiers, where, even then, they are not as ruler flat as other designers choose to be.

Hifi-News, RB-1590:
-0.03dB at 20 kHz, -0.3dB at 100 kHz

Hifi-News, RC-1590:
20 Hz - 100 kHz +/- 0.05dB

Stereophile, RB-1080:
Flat from 20 Hz to 20 kHz. -3dB at 110 kHz

Stereophile, RB-1090:
Flat from 20 Hz to 20 kHz, -0.5dB at 50 kHz

Stereophile, RB-960BX:
Flat from 20 Hz to 20 kHz, -0.1dB at 50 kHz

Stereophile, RMB-1095:
20 Hz - 20 kHz +/- 0.15dB

Stereophile, RMB-1075:
-0.39dB at 10 Hz
-0.11dB at 20 kHz
-0.66dB at 50 kHz

Hifi-Choice, RA-1570:
20 Hz - 100 kHz +/- 0.2dB

Australian Hifi, RA-12:
7 Hz - 550 kHz +/- 1dB

Soundstage, RA-1572 MKII:
10 Hz - 100 kHz +/- 0.5dB

 

[AmadeusMozart]

Tube amplifier do sound different from each other. This is due to the different implementations (or not) of global negative feedback and the amount of damping factor. Speakers react differently to different damping factors and some are a better match than others.

Solid state normally has a very high global negative feedback and a high damping factor (unless you have a "current feedback amp", IIRC there was a Marantz amp with that, there might be others) and that means most power amps will sounds the same.

However if using tone controls there has been a considerable change from the "old" (cheap?) tube (derived) tone controls and the modern computer derived ones. The tube ones introduce phase shift, some will say it is inaudible others will tell you it is audible. The modern tone controls (if implemented properly) are capable of having no, or hardly any, phase shift.

I'm sticking to a solid state preamp and a tube power amp - I had a mega expensive computer controlled solid state amplifier that went full rail one night taking the expensive speakers with it (unrepairable). I do not hear much difference between a real good tube amplifier and a solid state amp (when adjusted). And with the speakers being several factors more expensive than the amplifier I rather make sure that the speakers keep going. If the amp is a write off, too bad.

 

[SirPaulGerman]

Rotel have always had a 'house sound'. From day one in the 1970s.

Their amplifiers (and preamplifiers) roll off in the bottom octaves and also tend to be bandwidth limited somewhat in the top octaves. They are not, nor ever have been, DC- daylight response designs. It is deliberate.

What do you make of the Rotel RC-2000 preamp and RA-2000 amp ?
I have both pieces, when I got those they were broken, so I am on the face about a full restoration

Rotel RC-2000 Stereo Control Amplifier Manual | HiFi Engine

www.hifiengine.com

Rotel RB-2000 Stereo Power Amplifier Manual | HiFi Engine

www.hifiengine.com