Rotel RB-1070 Amplifier Review

[Pio]

In 2000, I had the 5 channel version: 1075 I believe was the model, loved it, sold it to a friend in 2011 and he still has / uses it.

 

[Ageve]

Maybe someday a Rotel class-D amplifier will find the way to Amir

A review of the RB-1092 would be very interesting. I've always wondered if there was something wrong with the measurements by Secrets of Home Theater. I know Class D amps were less than stellar back then, but this bad?

RB-1092 (Class D)

100W, 4 ohms = 1% THD+N @ 10 kHz (-40dB).

RB-1080 (Class AB)

100W, 4 ohms = 0.015% THD+N @ 10 kHz (-76.5 dB)

RB-1092, 100W, 4 ohms, 10 kHz + 11 kHz:

RB-1080, 234W, 4 ohms, 19 kHz + 20 kHz:

https://hometheaterhifi.com/volume_14_1/rotel-rb-1092-amplifier-1-2007-part-3.html

Rotel RB 1080 power amplifier Measurements

Sidebar 3: Measurements After the usual one-hour preconditioning at one-third power into 8 ohms, the Rotel RB 1080's chassis was pleasantly hot. However, the shrouded internal heatsinks (not those on the front panel) were way too hot to touch, which I assume is why they're protected from prying...

www.stereophile.com

 

[HarmonicTHD]

I guess its not easy . One way is to put the toroidal transformer in another box far away from other electronics. A better way is to use a modern switched power supply . Read this from the audio company Benchmark, 2016.

Audio Myth - "Switching Power Supplies are Noisy"

This Myth Goes Something Like This: "Switching supplies are noisy." "Linear power supplies are best for audio." We disagree!

benchmarkmedia.com

As much I respect Benchmark but that generalization is pure BS. Plenty of well engineered amps with no main hum and a linear supply with a toroidal transformer.

(Sorry for the OT)

 

[dtaylo1066]

I've always like the design aesthetics of most Rotel products. Good to see and old one perform decently on the bench.

 

[Hugo9000]

Many thanks to @amirm and the kind member who sent this in for testing! I bought an RB-1070 18 years ago, and it's still going strong. So is the RC-1070 companion control amp/preamp I purchased at the same time.

I almost didn't buy it due to Rotel not specifying output into 4 ohms, since my speakers are KEFs with a minimum at 3.2 ohms. Seeing Amir's test results at 4 ohms (206 watts, both channels driven), with max power into 4 ohms at 250+ and peak over 300 watts, I wonder why they didn't even state a conservative 4-ohm rating. Anyway, glad I got over my initial reluctance, since the amp has served me well for nearly two decades, delivering countless hours of beautiful music. Can't say I ever noticed a noise problem, but I try not to look for trouble and focus on the good and the beautiful with my music listening haha! If I owned a Benchmark or other amp of similar power but superior test results, it would be interesting to try to test if I could tell the difference or not with music.

 

[fordiebianco]

Just sold mine.

Darn.

 

[AndyBeckett]

This was a treat Amir, I own the RMB-1075 5 channel version as well as the RB-1080 200 watt version for the mains. Great performance for a 20 year old. That power on spike has tripped my electrics on occasion.

Always found my 10 series kit to get a bit harsh at high volume, any idea why?

 

[Thomas_A]

I’ve owned several Rotel integrated and have one power amp that has survived for many years. Rotel has always had good stuff, IMO.

 

[Ajax]

In 2005 I purchased a 1066 AV preamp with a 1075 5 channel power amp. I added an 12" tannoy active sub and used the system for both music and home theatre. It sounded very good to my ears with plenty of power and would most likely give today's all in one AV systems a run for their money.

Rotel enjoyed a reputation in Aus for good quality electronics and performance without the price tag.

 

[sarumbear]

This is however very good compared to many amps tested on ASR:

But does it matter if it’s flat or curved if distortion is much lower? Look at this modern amplifier, not only it has less distortion at any power but has 30dB less distortion at average listening levels.

 

[ReinhardS]

Warning: this device doesn't have a relais to disconnect your expensive speakers in the case of an DC-error or a short-circuit in the output-stage! It has an over-temperature protection. In the case of over-current from an output, fuses will blown. But thats a risk for getting DC on an output.

I have to say i don't like Rotel in general. The cases may be good, but i don't like to see schematics, where the component count was reduced to an extreme level. Here are even protective base resistors missing. Such parts costs just a few cents?!

 

[pma]

Test of Rotel RB 1080 in Stereophile, 2002, has shown similar distortion plots as @amirm new measurements of RB 1070. So it will be the topology feature.

Rotel RB 1080 power amplifier Measurements

Sidebar 3: Measurements After the usual one-hour preconditioning at one-third power into 8 ohms, the Rotel RB 1080's chassis was pleasantly hot. However, the shrouded internal heatsinks (not those on the front panel) were way too hot to touch, which I assume is why they're protected from prying...

www.stereophile.com

I agree with post #91 and I have to say this amp is nothing especially good.

 

[nick-v]

The RB-1070 was my first ever separate power amp. I bought it new way back in the day for around $1,000 CAD if I remember correctly. I was using it to power a pair of Paradigm Monitor 11v2 speakers via the preouts from a Yamaha RX-V1200 AVR with a Panasonic DVD-RP91 DVD-Audio/Video player as the source.

Nice to see that its performance is respectable at least.

 

[laudio]

When you can snag an Hypex NC252MP amp (with 12v trigger), for US$625 the Rotel for $500 looks lackluster for sure -- much higher noise and distortion.

For those that admit the sonic differences can exist between amplifiers, the distortion + noise spectrum for Rotel suggests that won't sound "harsh" but that it won't sound as detail or transparent as, say, a Hypex, and that it might sound a bit "grainy" -- granted, that will only be evident of one's associated equipment is very good quality.

Probably closer to mid 300 USD range these days in the used market.

 

[laudio]

I’ve owned several Rotel integrated and have one power amp that has survived for many years. Rotel has always had good stuff, IMO.

My first amp was a Rotel RA-210, 6.5 watts of musical bliss Wish I still had it.

 

[Thomas_A]

But does it matter if it’s flat or curved if distortion is much lower? Look at this modern amplifier, not only it has less distortion at any power but has 30dB less distortion at average listening levels.

View attachment 258910

It is predictable vs not. Audible difference?

 

[dshreter]

Just a good, reasonably priced and reasonably engineered commercial home audio product, nothing more.

You say that like it’s a bad thing. Is there a product contemporary to this one that you think represents substantially better value for money?

 

[PeteL]

It is predictable vs not. Audible difference?

I has predictably Higher noise and distortion at any frequencies. The fact that SINAD stays put as voltage increase is a bit of a concern no? It requires more digging. Does it means that the noise floor increase at the same rate as the volume? That would be a bit odd and not a good thing, If not it would mean that distortion start to increase as soon as you increase level, from zero. Also odd.

 

[Ageve]

Warning: this device doesn't have a relais to disconnect your expensive speakers in the case of an DC-error or a short-circuit in the output-stage! It has an over-temperature protection. In the case of over-current from an output, fuses will blown. But thats a risk for getting DC on an output.

I have to say i don't like Rotel in general. The cases may be good, but i don't like to see schematics, where the component count was reduced to an extreme level. Here are even protective base resistors missing. Such parts costs just a few cents?!

The idea was that a powerful amplifier should be able to handle a 2 ohm and even 1 ohm load. It's not useful with 99.9% of speakers of course, but you could get "impressive" current measurements using a short impulse at a very low impedance (look at the last image in my previous post, 242 Amps...). I have no idea why, but it was a thing back then.

Halfway through the RB-1090 product cycle (~20 years ago), current limiting was implemented, and it's been used since. I'm not sure about when or if it was implemented on the old RB-1070 and RB-1080. The service manuals found online are most likely for the first versions.

All modern Rotel amps have current limiting.

 

[DMill]

My first ”audiophile“ purchase was a Rotel 985 integrated. Quite an upgrade from my Bose Lifestyle 3. Previous generation to this one. It was a tank. I still miss that amp sometimes. Had the same on/off pop Amir noticed with this one which bothered me, but really not a big deal in hindsight. Back then, Rotel used to make a big deal about their damping factor >400. @amirm thanks for the review of Rotel from this era. Brings back some great memories.