29 August, 2011

Review: Rotel RB-870BX Amplifier

The day before last, in anticipation of removal, I took out my borrowed pair of JBL 4312A and tested it with the LFD integrated amp. I haven't used it in 6 years, yet it sounded simply wonderful. Before I write my LFD review, I'd like to tell you about my previous experience with this wonderful and under-rated loudspeaker. But first, let me introduce you to of this unassuming vintage stereo amplifier, life of the party.

pic of the innards from the internet (here). pic at the bottom of the article is from audioreview (here)

Review: Rotel RB-870BX amp (official literature here)
The RB-870BX is a 100 wpc stereo amp that doubles the power into 4 ohms (2 ohm not rated). It can be bridged via a small switch at the back (though you have to be careful about the speaker cable connection), and rated at 300 wpc into 8 ohm. Look at the impressive power transformer and bank of lytic caps, of good quality. My friend 300B123 once commented on the excellent components inside, deeming it a great candidate for DIY mods to take it to another level. While it may not be an absolute paradigm of high-current amplifier, it is no slouch and phenomenal value for money. I am sure its many cousins are similarly worthwhile.

One thing, the manuals used to be all available on Rotel's website, but doesn't seem so now (model is listed, but clicking it draws a blank), so download asap from other sources or cached copies if you are interested.

Rotel History
A diversion. Despite the internet, the true history of Rotel the company has been buried almost beyond excavation. The current official website, inferior to the old one, says nothing about the company's history, and reflects the superficiality of our age.

Here's something from the internet (2002): "...According to the Rotel site, the company was formed in 1961 by the "elder" Tachikowa and currently run by the son, Bob Tachikowa (one slight variation that I did come across was an audio site that listed the company as being founded in 1961 "by a Japanese audiophile" and then adopted by the Tachikowa family in 1979)...Tachikowa's address is listed as the Rotel offices in Japan but all research and design are driven out of the UK (and mfg out of Hong Kong)....So while Rotel could ceremonially be called a Japanese company, operationally its a UK company..."

A note from Taiwan's Audio Art magazine: "...
談 起Rotel的歷史,它原本 是六○年時期的英國製造廠商,成立初期就建立了良好的名聲,不過在七○年代末期一度瀕臨倒閉,幸好有了日本資金以及繼任總裁兼工程師Tony Mills加入,Rotel這個品牌才得以起死回生。1982年對Rotel來說非常重要,因為他們藉由一系列不同於以往的產品設計,開始受到市場的注 意,並且慢慢的穩住經營腳步。雖然Rotel已非昔日的純英資公司,但是其設計理念並不因為日資進入而有所改變,反而在品質控管上更加嚴謹,造就了 Rotel在保持傳統英國味道之外,還使得品質更加提昇;再加上合宜的價格,使得Rotel在中低價位市場上佔有一定的地位。..." Basically, the author implies the company was originally UK, but received infusion of Japanese capital in the 70's.

From another Chinese site: "...Rotel成立於1961年7月1日,但剛開始並非以Rotel為品牌,直到1969年才開始正式以Rotel為商標推出音響製品。由於早期 Rotel的英國經銷商推廣產品十分成功,許多人以為Rotel是英國品牌,但實際上Rotel總部位於日本東京。Rotel早期產品以擴大機與CD唱盤 等兩聲道音響為主,外觀平實但性能出眾,是公認「物超所值」的音響首選之一。目前Rotel的產品線已拓展到家庭劇院的領域。.."

It took a search of "Rotel + Tony Mills" to uncover what I think is the Definitive Rotel History as related in the website of Lyric HiFi USA, and I quote: "...The only Japanese electronics firm anywhere near its age still owned by its founding family and run by a family member, Rotel has operated continuously since the late 1950s, when it was Sylvania’s TV distributor in Japan.

By the 1960s, founder Tomiko Tachikawa was focusing on audio and building products for blue-chip U.S. hi-fi companies, including Harman-Kardon, H.H. Scott and Marantz, all of which had found Japan a cost-efficient source for reliable products.

The first Rotel-branded units appeared in 1969, but for various business considerations the firm continued manufacturing for other companies. As a result, when Consumer Reports magazine awarded an early Rotel-badged receiver a Best Buy rating back in 1973, it also gave high marks to two American-branded units that few people knew had been built in the same factory.

!!!Rotel maintained an especially long and fruitful relationship with Adcom and manufactured that firm’s GFP-400 tuner/preamp, its GFP-555/565 preamps and its GFA-535/545/555 power amp series. High end aficionados today consider those units classics.!!! I didn't know that!

When the first Rotel-branded hi-fi products came to market, Western consumers were reluctant to buy any gear identifiable as Japanese, but Mike Bartlett, now the firm’s vice president and general manager, had a solution for that problem. Mike, a fervent hi-fi fan since boyhood, joined Rotel in his native England in 1979. He was soon collaborating with a fellow British audiophile on an amplifier design project that would make Rotel a recognized high end brand.

That effort made perfect sense to Bob Tachikawa, the company founder’s son and Rotel’s current president, who is also a high fidelity enthusiast. Though born and bred in Japan, Bob had an in-depth understanding of the American audiophile market, gained during his student days at the University of Virginia, where he earned an engineering degree, and afterward during a four year stint at Rotel’s New York office. The muscle car he owned back then underscores his love of high-performance products: a Dodge Charger R/T, the vehicle used by the assassins who pursue Steve McQueen’s Mustang during the movie Bullitt’s classic chase scene.

As for Mike Bartlett’s design collaborator, Tony Mills, he had modified a mainstream Japanese receiver, the performance of which stunned Mike. If Tony could make a mass market unit sound so good, what could he do with a Rotel amp?

The audiophile pair decided to find out and, with Bob Tachikawa’s blessing, worked many a late night before completing a prototype for what would become the Rotel 820B amplifier, a unit that raised eyebrows when it was introduced three decades ago.

Tony Mills spent the next 15 years developing highly successful CD players for Rotel before retiring. At that point, another UK designer, Robert Burn, took up the torch and has since been refining the company’s audiophile units from his base in England.

I highly commend Lyric HiFi for this article, showing, despite their hi-end image, they care about even the details of the smaller guys. In comparison, the official website has completely cleansed itself of anything that smacks of the Japanese, in the interest of prestige and sales perhaps? Shame!

My Units
For a pittance, I got my first RB-870BX bundled together with its matching preamp, the RC-870BX (official literature here). While the preamp is quite nice, it really is not the match of a decent tube preamp (what is!). It does have a decent MM/MC phono section that should be the equal of many of today's cheaper outboard phonoamps.

It is the RB-870BX amp that is the star. It is rather modern sounding: fast and detailed. I noticed the mono bridging feature and decided to get a second one to try it out, and am I glad I did!

In the coming article on the JBL 4312A there would be some description of the amp used in both stereo and bridged modes.


  1. What a fun article. I have had the RB-870BX partnered with the RC preamp for the past 22 years. Bought them new in my home town of Nottingham and when I immigrated to the states, they came with me, one under each arm. They have served me so well, they are my friends - always puts me in the right mood with music that is clear and detailed. And, they can rock and roll fast. Nice imaging - just straight up nice two pieces of kit that I will never let go of. Kind of funny though, when I first got to the States, I paired them up with JBL 4412C's which sounded great to me at the time but, not knowing JBL moniters, I found out I had been sold 2 left speakers. After 10 years and too many moves, I let JBL's go. Replaced them with some Linn Katans plus the stands. Great little stereo. Sounds Incredible.
    I would like a bit of advice from you. These pieces have been flawless but I have been thinking of replacing them. After reading the article about upgrading them, is this a valid option over a new purchase?
    The two contenders if I go the route of new amps are:
    continuing with Rotel RC1580/RB1582 or, the Naim Nait XS integrated amp. I am leaning towards brand loyalty with Rotel however, the price seems a bit out of line. I do like that the Nait is made in the UK.
    So what do you think? Any thoughts would be appreciated no rush to reply. Thanks,

  2. Hi Rich:

    If anything, the older Rotel amps are better built than current ones, and I'd not advise changing to a new Rotel amp. Period.

    Neither do I think the Nait XS an upgrade. Since you have UK connections, if you want to try out Naim, I'd rather buy an old Naim unit and have someone ship to you.

    The way I'd go is to upgrade the preamp. A tube preamp, even a relatively cheap one, makes a tremendous difference! In the US, get an MFA Magus (getting hard to find) or a Counterpoint 3.1 or 7.1 and you would be in heaven. These even have built-in phono!

    From the UK, the rave reviewed Croft Micro 25 comes in 2 versions, the regular one at 700GBP and the Basic version at only 400GBP. And that includes phono too! I'd love to try one! If you get one of the internet venders, the VAT reduction should cover postage.

    You can keep the RC preamp and use its phono section if you are still into vinyl.

  3. Hey Dr. John,

    Yes, I am very much into vinyl. I have a Thorens 321TD with an SME 3009 Mark II tonearm and an entry level Audio Technics cartridge which I am thinking of upgrading. My research has me considering the Denon DL-103R. What is your opinion of that? Any other recommendations would be kindly appreciated.

    Thanks for your thoughts on the new Rotels and Nait gear. I will definitely take your advice.

    I did have a quick look at the tube preamps that you recommended. The UK ones were more visually appealing to me but bottom line, it does come down to sound. Are the MFA Magus and Counterpoints American amps? I am going to do some reading about these.

    Looking forward to the upcoming article with the 4312A JBLs.

    I have the original brochures of the Rotel RB/RC 870BX with specs and reviews. I can scan them and email to you if you would be interested.

    What are your thoughts about speaker cable? What I have now are the Monster MCX-IS which I am bi-wiring.

    Nice talking to you Dr. John. Looking forward to hearing from you again.


    1. i 'd be interested in the brochures.

  4. Upgrading the cartridge is something you should have done a long time ago, and there is nothing really better than the Denon 103 or 103R at least up to US$1000. They are low output MCs; not sure if the Rotel MC section is up to it. If not, get a step-up transformer, something like Bob's Device or if you can DIY, a kit from K&K.

    MFA and Counterpoints are old American brands. There is great choice of older tube preamp with phono out there. Another worthwhile pick for a few hundred dollars is the Audio research SP-9. Start browsing Audiogon! :-)

    Speaker cables? Simple. Nothing better than Gotham; they work with everything. The fellow in Gotham USA is a super nice guy. The coaxial 50150 is very good, as is the softer 2 conductor 50025. You should get their interconnects too, if you can terminate yourself.

    Where are you in the US?

    BTW, the JBL post was right after the Rotel post!


    The stacked pair is simply awesome! Most cost-effective!

  5. I am in PA just 20 miles away from Gotham Cable. Not many reviews on the cables, the one I did find was on the interconnect cable which was rated pretty badly. The prices seem to be very reasonable on the speaker cable - I will definitely give them a try. The interconnect cables that I am using now are the Monster M 1000i. A pair from the cd player to the preamp and another pair running from the preamp to the power amp. They have been there for about 10 years and I am very happy with them.

    Yes, you are absolutely right about the cartridge update but...... Priorities.

    Actually, I made a mistake with the model of JBL's I had. Mine were the 4312c - looks the same as the ones you tested. Looking at the picture, the tweeters are both on the same side so....I am wondering if I had 2 lefts after all. I think I paid around $600 for mine new. The Rotel chewed them up. I must have gone through 3 tweeters and 2 woofers in the time I had them. Led Zepplin I sounded amazing on there, like the album was actually produced on them. Vivaldi's Four Seasons sounded very nice too but, the Linn Kanters put Vivaldi into a different league, gorgeous sound.

    I love the name Counterpoint and the history of the company. Yes, I do go to Audiogon.

    Thank you for all the info. I will continue to read your blog, it is fun and interesting. Keep up the good work.



  6. Hi Richard,
    I have 2 x RB870BX matched with the RC850.
    I woul love to get a copy of reviews you have of the 870.

    Great article, I truly enjoyed reading it.

    Thank you,

  7. Hi Golanr,

    I would be happy to get the review to you. I have tried posting a picture to the blog but it would not take it so, if you get me your email I can scan and send to you there.
    It is a good article, 2 pages with lab reports, sound quality and specs printed from Hi Fi News and Record Review, January 1988.

    Doctor John,

    Referring to your post about upgrading your SME tonearm and the Denon cartridge, just curious, why do you feel it is not versatile enough?

    Where abouts are you located?

    Best Rich

  8. This comment has been removed by the author.

  9. Hi Rich,
    Sorry, I provided the wrong email.
    It is rotel870bx@hotmail.co.il

    Thank you,

    1. Hi gents! i bought Rotel RC-870BX pre-amp & RB-870BX power amp for 200 british pounds.. did i get a good deal? cheers!

    2. Well, that is always relative. If you forgo sleep and lurk 24/7 on Ebay I am sure you can have them for much less! :-) But if they are in great shape and you see the real items I'd always pay a little more.

      In the end, the real question is are they worth that much. Yes, they are.

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  12. AnonymousJuly 21, 2013

    I bought a second hand Rotel 870BX amp & preamp on my 18th birthday for €450
    Now I'm 37 and I still listen to this setup everyday. I will never part with my rotels!

  13. Hey this is a great blog. I have a question for you. I have an option to buy the power amp but no pre amp with it. Can you suggest any other pre amp to match?

  14. As i mentioned in my article, nothing beats a tube preamp.

  15. Hi, I have two Rotel Rb 870 bx, i thing connect in bridge mode for speakers B&W CM7, what do you thing about this?. anybody can send me reviews for this amli?, thank you.

  16. I did try the bridged mode later, as I wrote in this JBL4312 article:


    Basically, the sound coarsens a little, but reasonably so. If you need power it is a good way to go. The CM7 should be not too difficult to drive and relatively easy load, so by all means give it a try!

    1. Thank you,

      The principal problem Is The minimun impedance of b&w cm7 are 3 ohm, The minimun impedance of ampli rb 870bx in bridge mode Is 8 ohm. This aspect Is dangerous, you know The minimun impedance of The jbl 4312a speaker? Doyou Think about this?. Thank you.

  17. Perhaps. Indeed I know in bridged mode impedance handling is weakened. It all depends on heavy you use the amp (how loud you play etc). Cannot advise you further.

  18. Hi,

    My 1st post here to know if the Change from a Sansui BA2000 for a Rotel RB1582 is a good move or not?
    Thank you.

  19. I'd GUESS it would be more of a lateral move than dramatic improvement. The Rotel likely will have more power and be more modern sounding; the Sansui warmer and more enticing with the right speakers. I'd save up to upgrade to something even better.

  20. I unfortunately parted with my RB870bx back in 2002, and my PROTON AP-1000 pre. amp. Possibly the single one stupid thing I ever did ... Still miss them both, especially the control of the RB870bx when it comes to difficult speakers...

    1. Nothing to fret about. You can always get a Rotel amp of that era for a reasonable price on Ebay whenever you want.

  21. hi there, i have a question i need a new amp for jbl 4312 mk2. do you have anny suggestions ? i like your blogs always read it, srry for my bad english.
    thanks best regards

    1. Ah...the 4312, like most JBL's can be driven well by either solid state or tube. Any quality amp will do well, but higher powered ones do better than lower powered ones.

  22. thanks for answere me, anny suggestions ?

    1. What are the rest of your equipment, and how big is your room?

  23. hi,i have a arcam dac room is 4 x 9 meters speaker cable western electric, interlink belden 4402.

    1. That's a long and narrow room, a bit of a challenge. You must find the best way to put your speakers. There's no end to good gears: for best effect, get a tubed preamp and a good amp. But a good integrated will do. Can't advise more.

  24. Hi thanks, i can buy a nad c272, annybody know if this is a good amp ?

    1. Later NAD's are good amps, but they do not have the magic of the original 3020.

  25. Yes i know, i still have a nad 1020 series 20 preamp, its the preamp from the nad 3020.

    1. Good then, any amp will do as it is the 1020 that does its magic.

  26. Hi Doc,
    I have had this amp since new and I love it. Because of space requirements I wanted to get something smaller so I ended up buying two Rotel RMB 100 monoblocks. I thought they would be an improvement, however, I feel like they sound a little muddy and don't have any separation. Maybe it is a bit of buyers remorse but I have listened to 4-5 songs I know well back to back alternating between amplifiers and it just doesn't have the same clarity. Is the design of the amp simply inferior, or could it be something else? I was honestly expecting them to sound as good or better than the 870BX and I'm a little disappointed. My speakers are Sonus Faber Concertos.

    1. Ah, the vagaries of audio! When this kind of thing happens, it is indeed frustrating! We have all experienced it!

      Despite what many believe, monoblocks are frequently not as good as stereo amps. A technician once commented that the separate power supplies are not as synchronous as in a stereo setup. I believe this. Take McIntosh tube amps - the monoblocks MC-40 and MC-75 are widely regarded as inferior sounding to their stereo progenitors, the MC-240 and MC-275, respectively.

      You can experiment with connections. You can try to forego bi-wiring: Use quality jumpers (like a short strand of professional speaker cable) for your SF Concerto and use single wire speaker cable and just one set of outputs of the monoblock; you have the option of connecting the red to either the tweeter or bass red, and the black to either the tweeter or bass black. All 4 permutations will sound different, see which one you like.

      I am not familiar with the RMB100, but it is my belief that later Rotels are not as good as earlier ones.

      If u still have the 870 BX, and if space permits, get another unit and use them either as monoblocks or bi-amping.

  27. I've had a pair of these RB870BX as a monobloc pair for the past ten years or so. Rotel 960RSP pre amplification and Mordaunt Short 908 speakers. Great set up. Plenty of power of course but what I really like is the huge easy sound at low volume which is of course the primary listening mode.