• WANTED: Happy members who like to discuss audio and other topics related to our interest. Desire to learn and share knowledge of science required. There are many reviews of audio hardware and expert members to help answer your questions. Click here to have your audio equipment measured for free!

Rotel RB-1070 Amplifier Review

Rate this amplifier:

  • 1. Poor (headless panther)

    Votes: 3 1.1%
  • 2. Not terrible (postman panther)

    Votes: 46 17.2%
  • 3. Fine (happy panther)

    Votes: 183 68.3%
  • 4. Great (golfing panther)

    Votes: 36 13.4%

  • Total voters
    268

laudio

Active Member
Joined
Dec 30, 2019
Messages
291
Likes
294
Sometimes meters are overrated

pa7.jpg
 

Dmitri

Senior Member
Forum Donor
Joined
Jul 25, 2020
Messages
432
Likes
1,057
Sometimes meters are overrated

View attachment 262052
The PA-7 was originally a Darth Vader “ArtHaus” design. Fun fact…Nakamichi turned the on power led from Vader’s proprietary ”Sinister Red” to the less controversial green shown here to avoid confusion and PTSD flashbacks amongst their customers. ; )

That is one gorgeous piece of eye candy….
 

pieterv1

Member
Joined
May 6, 2021
Messages
41
Likes
14
I recently picked up a Rotel RB-06 to match my RC-06 preamp.

I noticed that the amplifier board actually has 4 spots for the large output transistors that are not populated (so it has 4 per channel instead of 6). The same board is probably used in a different model with more power, even though the RB-06 with its release didn't have a heavier sibling. Maybe the RB-1552 which came out 2 years later? Unfortunately I can't find a service manual of that one.

The topology is very similar to many other Rotels, including this RB-1070 so I'm wondering if maybe I could add these additional transistors. Not sure if it'll just add power or also just better performance/precision, some change in sound...

And maybe the power supply might not be able to handle the extra power. Just veeeeery curious
 
Last edited:

Martin_320

Active Member
Joined
Feb 14, 2020
Messages
106
Likes
93
Definitely not normal. Whether it is the house wiring or the amp is hard to say.
Maybe that's a characteristic of Rotel high-current amps. My 5-channel RMB-1075 (pictured in post 194 above) makes the lights in my room 'blip' momentarily when I turn that on.
 
Last edited:

restorer-john

Grand Contributor
Joined
Mar 1, 2018
Messages
12,579
Likes
38,278
Location
Gold Coast, Queensland, Australia
I recently picked up a Rotel RB-06 to match my RC-06 preamp.

I noticed that the amplifier board actually has 4 spots for the large output transistors that are not populated (so it has 4 per channel instead of 6). The same board is probably used in a different model with more power, even though the RB-06 with its release didn't have a heavier sibling. Maybe the RB-1552 which came out 2 years later? Unfortunately I can't find a service manual of that one.

The topology is very similar to many other Rotels, including this RB-1070 so I'm wondering if maybe I could add these additional transistors. Not sure if it'll just add power or also just better performance/precision, some change in sound...

And maybe the power supply might not be able to handle the extra power. Just veeeeery curious

It's common with many brands to share the power amp board through a few models in a range. Yamaha have done it for decades.

The differences are not just a few extra OPTs. The transformer/s are more capable, higher voltages, the rectifiers are upgraded as are the filter capacitors, along with changes to bias currents and sometimes driver transistors as well. And, the protection circuit values all change as well.

So, just leave the RB-06 the way it is, is my suggestion.
 

RenSong

Member
Joined
Dec 5, 2021
Messages
31
Likes
31
Location
Lake Stevens, WA
Maybe that's a characteristic of Rotel high-current amps. My 5-channel RMB-1075 (pictured in post 194 above) makes the lights in my room 'blip' momentarily when I turn that on.
It's super quick but my room light will do it. Hasn't tripped the breaker in months though
 

AnalogSteph

Major Contributor
Joined
Nov 6, 2018
Messages
3,334
Likes
3,278
Location
.de
I always hate it when people whack in these huge crossover film caps in places where they clearly don't belong. It looks silly, not to mention the parasitics - you can even make an amplifier oscillate in some cases. If you must use a film cap, please, get some decent WIMAs or something. MKP4 4.7µ/100V are not outrageously large at least (13 x 24 x 31.5 mm, lead spacing 27.5 mm).
 

restorer-john

Grand Contributor
Joined
Mar 1, 2018
Messages
12,579
Likes
38,278
Location
Gold Coast, Queensland, Australia
I always hate it when people whack in these huge crossover film caps in places where they clearly don't belong.

And mucking around with bridge rectifiers. (look at that bodge with the matrix board)
 

pieterv1

Member
Joined
May 6, 2021
Messages
41
Likes
14
And mucking around with bridge rectifiers. (look at that bodge with the matrix board)
Maybe some extra context is necessary :)

I only got this amp 2 weeks ago and most of the mods had already been done by the previous owner, including those rectifier bridges.. Many of the mods I would've never thought of and some I have reverted in the meantime. The diodes are definitely not cheap and they do the job so I'm just going to leave them be. At least the aluminum piece offers some decent cooling. He also had added 2 AC line filters which didn't make any sense to me. One was sticking out at the back and he had also completely changed the wiring around the transformer/power switch...

As for the film caps: he had installed some cheap 600V LCR monsters (see pic). His reasoning was that this capacitor position was in the signal path. I did consider Wima's, but can't install them at this position with their short leads. The smaller 160V Mundorfs, for audio use, seemed like a good compromise. They're not much larger than the 100v Wima's and they have long leads which made them easy to solder (with the necessary isolation on the leads of course)

I must say, when I just received the amp, I was a little disappointed compared to my Quad 405-2 which I had just sold. The Rotel sounded pretty harsh.

I only just finished working on it yesterday. I got rid of the outboard ac filter, did a full recap - this time including the power filter caps and reverted all the wiring to original, according to the service manual.

This is going to sound very cliché, but after all the work it does sound in fact sound remarkably better. It has more body and the harshness has been reduced into nice presence & sparkle. All in all I'm very happy with the way it sounds now so no regrets about the Quad anymore. :)

I'm still thinking about replacing the small orange pp caps with polystyrenes. Any other suggestions welcome!

!! Old picture of the state I received it in ;)

s-l1600 (4).jpg
 
Last edited:

pieterv1

Member
Joined
May 6, 2021
Messages
41
Likes
14
I always hate it when people whack in these huge crossover film caps
I see where you're coming from. :)
See previous comment!

Is there really a disadvantage to using axial PP caps (used mostly in speaker crossovers) instead of PP Wima's apart from physical aspect? I don't hear/measure any oscillation. The caps sit right after the rca input, in the audio path. I can always just revert it to the original electrolytic, but also at work, my colleagues told me it doesn't hurt to have a filmcap at this position.
 
Last edited:

Joffy1780

Addicted to Fun and Learning
Joined
Jul 31, 2022
Messages
655
Likes
517
Always loved the look of these big Rotels :cool: Brilliant review and, as others have said, Amir has just increased the value of these, no doubt!!
 

restorer-john

Grand Contributor
Joined
Mar 1, 2018
Messages
12,579
Likes
38,278
Location
Gold Coast, Queensland, Australia
Is there really a disadvantage to using axial PP caps (used mostly in speaker crossovers) instead of PP Wima's apart from physical aspect?

Due to their size and placement, they can actually pick up noise- moreso than a physically tiny cap mounted on the PCB. The left channel axial PP is sitting right up against the PSU filter cap- I would expect some coupling of ripple noise under load.

Personally, I would return the entire amplifier to stock, measure and determine what, if anything, is on the table for improvement.
 

pieterv1

Member
Joined
May 6, 2021
Messages
41
Likes
14
Due to their size and placement, they can actually pick up noise- moreso than a physically tiny cap mounted on the PCB.
Interesting! Thanks for the info!
The left channel axial PP is sitting right up against the PSU filter cap- I would expect some coupling of ripple noise under load.
Are you talking about the picture with the white Mundorfs or the one with the big black film caps standing upright? The mundorfs I got instead, are substantially smaller already.
When I install the polystyrene capacitors, I'll put back a 4,7uF electrolytic cap as well and try to hear if there's any difference.
 

cybernaut667

Member
Joined
Feb 29, 2020
Messages
74
Likes
46
I got the pre amp RC-995
and I would like to match it with class D purifi through XLR.
Nice phono stage .
It would be good to see some measurements of this;)




There was some concern about these Rotel models being made in China, however a friend of mine has the RB-991, a more powerful predecessor of this, it still works very well after 20+ years now.
 

notsodeadlizard

Senior Member
Joined
Feb 18, 2023
Messages
403
Likes
362
In the FFT, odd harmonics are much smaller and a beautiful monotonous decline in amplitudes is visible.
If someone is interested in “tube sound”, then this is a completely tube sound, the main thing is not to drive the amplifier into clipping.
It's the right amp.
 

JktHifi

Senior Member
Joined
Mar 9, 2023
Messages
387
Likes
195
I like this amp because no sub-out.

Everything Should Be Made as Simple as Possible, But Not Simpler​

 

Beave

Major Contributor
Joined
May 10, 2020
Messages
1,329
Likes
2,728
I like this amp because no sub-out.

Everything Should Be Made as Simple as Possible, But Not Simpler​


Are there *any* stand-alone two-channel power amplifiers that have subwoofer outputs?
 
Top Bottom