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Amber Series 70

Stereo Power Amplifier (1978-85)

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Amber Series 70


Power output: 70 watts per channel into 8Ω (stereo), 200W into 8Ω (mono)

Frequency response: 20Hz to 20kHz

Speaker load impedance: 4Ω (minimum)

Year: 1978



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Reviewed Mar 09th, 2019 by Will Wilkin

I bought my Amber Series 70 power amplifier used, in 1988, and it served me very well until February 2019, when it went completely dead. The only time I ever had any service to this amp was in the 1990s when I listened to very loud rock music: I lost a channel and replaced a burnt fuse myself, located on the side of the amp, in between the heat sink fins. Mostly now I use it for classical and opera CDs, but since that includes some pipe organ music it still gets some pretty hard use, not to mention occasional old Aerosmith or Who albums (on CD).

I think the amp was made in 1977 or 1978. It has the silver faceplate, no stripe. The guy I bought it from recommended I always leave it on so it would be warmed up for optimal sound. And so I have probably turned it on and off only around 100 times in the past 30 years, mostly during electrical storms or to move it. The seller actually had a pair of these amps, modified either by him or the factory, with a switch in back to select stereo or mono input when it was switched to mono output. He ran them mono, one for each of his 2 speakers. I would have bought both but, even at his bargain $190 each, I could only afford one of them at the time, so I've always run it as stereo input and stereo output. He loved Amber so much I saw he had just replaced them with a nearly identical pair of amps, he said the reason was his new ones had a stripe across the front panel (to match his new Amber preamplifier, if I recall correctly). This is the only truly hi-fi amplifier I've ever owned, and I have always loved it though I don't have experience with other amps to make any comparative judgements.

Finally last month it went completely dead, no light comes on when switched on. I had serious electrical problems at my house, when my 1949 utility meter housing began arcing and crackling and soon left me with only one of the 2 lines coming in from the street. It took me a few days to locate the problem, during which time only some 120VAC circuits worked EXCEPT when the stove was turned on, when the burners wouldn't get hot but then my other lights would come on, dimly. Sometimes erratically those circuits would come on dimly even with the stove off. No doubt a day or two passed in this situation before I noticed the problem, due to my being away from home a lot.

Reflecting now on what it all meant, it must be that the 120V circuits on the dead line would get reduced voltage (around 60-80) when the stove was on (or when the failing meter housing was still passing arcing unstable current on that line). So my theory is the amplifier drew erratic and higher current when it was getting erratic and reduced voltage, since even though I never played any music during that time it was still idling on.

Also I should mention that in the past few months I think the amp had developed a quiet hum that, when the stereo was silent, I could detect coming through the speakers. I wonder what caused that?

My system also includes a Rotel RC-9808X preamplifier (bought new for about $500 in the 1990s), and a pair of Mirage M-895is speakers bought around 1997. Never had any problems with any of that. I'm assuming those all still work, since the Rotel power light comes on. But until I have a working amplifier, I will have a little anxiety over the condition of my preamplifier that I also always leave on.

Reviewed Feb 07th, 2019 by theaudiohiffle

I currently have an early S-70 in my second system, driving Thiel 2.2 speakers, and fed by a Carver C-2 preamplifier. This combo punches way, way above its weight class, sounding very similar to my main system of Audio Research SP6 (refurbed) feeding Outlaw M200 monoblocks into Thiel 3.5 speakers.

This is my second Amber .... I bought one way back in the 80's after its glowing review in the Abso!ute Sound and used it in my system for several years. I then sold it (for a song) along with a Citation 11 to my best friends who are classical musicians. Those two pieces still work flawlessly and sound great in their system.

A S-70 in good working condition is one of the best bargains in hi-fi, in my opinion. I rate it only 3-1/2 starts simply because equipment this old does not use modern and more transparent passive devices in the signal path. Accordingly, while neutral musically it has a slightly old fashion high-end sound.

Reviewed Feb 16th, 2016 by ecb015

I worked at Amber in 1980 in exchange for parts to build my own amp. The LM391 were hand selected to not need offset adjustments. All amps were burnt in at half power both channels better than FTC specifications. Output transistors were still being matched in those days. The owners were UVa students, one EE and the other a business major. The name Amber is based on the color of the LED, which was new then.

Reviewed Jan 21st, 2015 by TBroosteRR

I've been messing around with Amber amplifiers since 1983. I have 3 series 70 amps that I have hooked up as monoblocks. I had them upgraded by a guy in town and they are just great. Good separation, base response, power output and highs are clear and beat seems to be right on with no delays. The distortion is very small and they are very quiet solid state amps. They have been reliable. Only regret is, that I bought these from people used and not new. Each amp has a switch that will make them monoblock or stereo. So, you actually only need one for your stereo. I've never used them on anything but audiophile speakers and pre-amps. They should be able to preform in any situation. They don't smell when heated up. They don't get to hot, because of the cooling fins on each side. They are heavy and I guess weigh about +/- 27 pounds each.



re: Series 70

I just added another Amber Series 70, this one a very late model with all the tech changes. It sounds even better than the one I reviewed above. It is now in the main system. Whether it stays there time will tell, but I find it amazing that this 40 year old amp can still compete!

re: Series 70

Hi I have an Amber Series 50C on the bench undergoing repair. I'm rebuilding the entire left channel on one side on discovering a number of charred parts. Fortunately, all the tracks are in good nick, so I got the go ahead for repair.

Thing is, some of the resistors are unidentifiable, and a meter will not help here. In the absence of any schematic diagrams or service manuals, can anyone help me out?
Rhea Bonsey

re: Series 70

re: Series 70

Thanks for thew great info on the s-70. Could you possibly tell us what upgrades you had made to the amp?


Bob Cham

re: Series 70

High end amplifiers intentionally didn't have output protection relays. Keep the contacts clean on the PCB. When mine failed many years later it took out my speaker too. So fuse to the lower rating of the speaker and use with a passive subwoofer. At least use the high pass caps from the subwoofer crossovers to protect you book self speakers. Believe it or not, high end speakers like the old Infinity Kappa towers have DC blocking caps on all of their speakers including the woofer. The higher ones are called crossovers.

This website is not affiliated with or sponsored by Amber. To purchase Series 70 spares or accessories, please contact the company via their website or visit an authorised retailer.