Sansui AU-111, 907 NRA, Alpha 907 Review

[Sansui77]

Sansui AU-111, 907 NRA, Alpha 907 - Review 2019

 

Sansui Nutters!!!!!

 

I have the pleasure in owning the following amplifiers from Sansui. Most of my collection is pre 1980's but i have started to get into the Alpha line from when the first Alpha's were released in the mid 1980's . This review is not biased towards any particular decade of the Sansui lineup but just my thoughts (opinion) on how they compare, but more importantly where Sansui as a company were heading towards it's sound signature before the end days when they closed in 2001 - 2002. BTW, I'll do my best to explain how they compare in their sound signatures.

 

1. The famous AU-111 tube amplifier (1966)

This has been restored with all tubes, caps & some resistors replaced as needed. Still has the original main filter caps fitted.

 

Specs

 

Power output: 40 watts per channel into 8Ω (stereo)

Frequency response: 20Hz to 50kHz

Total harmonic distortion: 0.8%

Damping factor: 15

Input sensitivity: 220mV (line)

Signal to noise ratio: 70dB (MM), 80dB (line)

Channel separation: 45dB (MM), 50dB (line)

Output: 2.1V (Pre out)

Speaker load impedance: 8Ω to 16Ω

Dimensions: 460 x 170 x 345mm

Weight: 24.5kg

 

 

2. Sansui Alpha 907 NRA (1998)

All factory original. No repairs or mods have been done to this. 

 

Effective output (10Hz - 20kHz) Both channel simultaneous operation	190W+190W (6ohm) 160W+160W (8ohm)
THD (at the time of an effective output)	0.003% or less (8ohm)
Cross modulation distortion	0.003% or less (8ohm)
Dumping factor	150 (8ohm)
Frequency characteristic (1W)	DC-300kHz+0 -3dB
Input sensitivity/impedance	1V / 10kohm (1kHz)
SN ratio (A network)	120dB or more
Dynamic power	580W (2ohm) 390W (4ohm) 310W (6ohm)
TIM distortion (SAWTOOTH)	Below a limit-of-measurement value
Slew rate	200v/microsec
Rise time	0.5microsec
Input sensitivity/impedance (1kHz)	Phono man month: 2.5mV / 47kohm Phono MC: 300 microvolts/100 ohm compact disk, Tuner, Line, micro disk/Tape1, Tape2:150mV/20kohm
Phono maximum permissible input	MM(THD 0.01%):210mV MC(THD 0.1%):21mV
the frequency characteristic (1W)	Phono man month: 20Hz-20kHz�}0.2dB compact disk, Tuner, Line, micro disk/Tape-1, Tape-2:DC - 300kHz+0 -3 dB
SN ratio (A network)	Phono man month: 90dB or more Phono MC: 75dB or more compact disk, Tuner, Line, micro disk/Tape-1, and more than Tape2:110dB
Tone control	The Bass maximum variation: �}6dB (50Hz) The Treble maximum variation: �}6dB (15kHz)
Subsonic Filter	16Hz (-3dB), 6dB / oct
Loudness	+4dB(50Hz) +3dB(10kHz)
Power dissipation	400W
Dimensions	Width 462x height 165x depth of 448mm
Weight	33.0kg

 

3. Sansui AU-Alpha 907 (1986)

 

Same as the NRA, all factory original. No repairs or mods have been done to this. 

Effective output (10 Hz to 20 kHz, both channels driven)	190 W + 190 W (6 Ω) 180 W + 180 W (8 Ω)
Total harmonic distortion (at effective output)	0.003% or less (8 Ω)
Intermodulation distortion factor	0.003% or less (8 Ω)
Dumping factor	100 (6 Ω)
Frequency characteristic (1 W)	DC to 300 kHz + 0-3 dB
Input sensitivity / impedance (1 kHz)	Normal: 1V / 5kΩ Balance: 1V / 5kΩ
SN ratio (A network)	120 dB or more
TIM distortion (SAWTOOTH)	Below the measurement limit
Slew rate	± 200 V / μsec
Rise time	0.5 μsec
Input sensitivity / impedance (1 kHz)	Phono MM: 2.5mV / 47kΩ Phono MC: 300 μV / 100 Ω CD, Tuner, Line, Processor: 150mV / 47kΩ Tape play / DAT-1, 2, 3: 150mV / 47kΩ
Phono maximum allowable input (New IHF, THD 0.01%)	MM: 210mV MC: 21mV
Frequency characteristic (at 1 W)	Phono MM: 20 Hz to 20 kHz ± 0.2 dB CD, Line, Tape play / DAT-1, 2, 3: 1 Hz to 300 kHz + 0-3 dB
SN ratio (at 1 W)	Phono MM: 88 dB or more Phono MC: 70 dB or more Tuner, Line, CD: 110 dB or more Tape play / DAT-1, 2, 3: 110 dB or more
Tone control	Bass: ± 5 dB (50 Hz) Treble: ± 5 dB (15 kHz)
Turnover frequency	75Hz, 150Hz, 7kHz
Sub sonic filter	16 Hz (-3 dB, 6 dB / oct)
loudness	+8 dB (50 Hz), +6 dB (10 kHz)
Rated power consumption (Electrics Control Act)	370W
External dimensions	Width 448 x height 160 x depth 441 mm
weight	28.0 kg

 

 

Setup:

Source: Asus mini laptop (optical out) using foobar 2000 through Matrix DAC.

Speakers: Spendor BC1 (Recapped x-overs) on open stands angled inwards but slightly angled outwards of listening position. Ear level position set between the Celestion HF1300 mid-range & Coles 4001G super tweeter. Distance 4 Meters from speakers to listening position.

Carpet room 7 x 3.5 meters.

 

"Let the product speak for themselves"

I had a good listen to both the first generation 907 and the NRA yesterday through my Spendor BC1's which I've decided to keep. I just couldn't sell them as they are such a great listen, very detailed speakers with a beautiful mid-range. The mid band /mid-range is the most important aspect of a great sounding system imo. The 907 was played in the morning then the NRA at night, same source same speakers.

 

First of all I must say the older first generation Alpha 907 is a damn good listen [emoji54]WOW!!!!! The 907 is not as detailed and polished like it's newer brother NRA but is the most powerful of them all @ 180Wrms per channel. It still a lovely listen and I could easily be happy to just own this and be done with it but I need to explore where Sansui was heading. Comparing to the NRA's sound, I would say the NRA comes across more finetuned a more polished sound with greater detail compared to the Alpha 907. It's not a huge difference but you can tell. The NRA settings @ flat are absolutely perfect. I was really surprised at whatever music I was feeding it, it just didn't require additional adjustments where both the Alpha 907 & AU-111 at flat are more bass heavy. Actually, the AU-111 is the most heavy on the bottom end and I had to back it off from 12 to the 9 o'clock position. I played all types of music yesterday and decided to put Madonna's immaculate collection on as I think it's a beautifully recorded & produced album, plus I remember listening to it through the AU-111 a while back and couldn't stop smiling. The NRA & the AU-111 are closer than I had thought from what I remember listening to the AU-111. They both have a beautifully rich smooth detailed accurate sound and both seem to do really well giving a 3D image with an amazing sound stage, it's that good. I would give the upper hand to the AU-111 in this department only because I feel it gives you a little more seperation in the sound stage. Apart from the 111's bottom end slam, they're almost identical in how they voice in the mid-range to the silky top end. The NRA i feel is a little cleaner - clearer in the SQ department but not by much and that also depends on what type of music is played at the time. Studio albums suits the NRA to a T for it's beautiful even control throughout the audio spectrum where's the AU-111 for it's bottom end would suits live performances. I feel that both are very close with little differences and Sansui may have tried to use the AU-111 as a reference standard but improving on making the sound even more detail with great success. The NRA and any Alpha for that matter are just beautifully built - sounding masterpieces. At the moment the AU-111 has a magical sound with an amazing sound stage that would make anyone listening to it smile and say, how does a 50+ year old tube amplifier sound so good.

 

Next is to get a couple more Alphas to the list and we'll see what happens with that.

 

 

 

 

 

 

 

 

Edited July 15, 2019 by Sansui77

[BLAH BLAH]

Very nice review Mark...

Glad you did'nt sell those Speakers!

 

[blakey72]

Good work Mark, looking forward to more from you. Ahhh I'd love a 111, you're a lucky man. I haven't heard the other Alpha 907's except one of Jeff's newer ones on his Lenehan's. I could hear more detail in his as you said. I think the standard 907 isn't as detailed but is excellent for rock/metal/hip hop. It just has ample power sounds big. 

 

I tend to use my Plinius/Exposure for slower stuff with more detail. I haven't heard a 111 however it's on my bucket list. Do you think you could tell the 111 is a valve compared to the NRA or are they just too close?

[blakey72]

6 minutes ago, BLAH BLAH said:

Very nice review Mark...

Glad you did'nt sell those Speakers!

 

Glad you didn't sell that amp!

[Sansui77]

Good work Mark, looking forward to more from you. Ahhh I'd love a 111, you're a lucky man. I haven't heard the other Alpha 907's except one of Jeff's newer ones on his Lenehan's. I could hear more detail in his as you said. I think the standard 907 isn't as detailed but is excellent for rock/metal/hip hop. It just has ample power sounds big.    I tend to use my Plinius/Exposure for slower stuff with more detail. I haven't heard a 111 however it's on my bucket list. Do you think you could tell the 111 is a valve compared to the NRA or are they just too close?

 

 

Value wise, about the same mate. Both cost about the same for me anyway. AU-111 from Japan and the NRA was a local purchase. 

I love the AU-111 for its imaging and sound stage it throws out but the NRA is just so well built, quality components for what you pay for them. It's a credit to Sansui for making these masterpieces before they shut shop.

 

 

 

 

 

[Sansui77]

Looks like this is about to happen early next year. I'm so excited. New review coming in 2020

907 NRA vs AU-111 vs 907 Limited

Edited December 17, 2019 by Sansui77

[Sansui77]

 

 

 

[Cafad]

Any updates to this thread for the new year?

[Sansui77]

On 21/04/2020 at 7:48 PM, Cafad said:

Any updates to this thread for the new year?

Mid year update... certainly. I have a 907 Limited to add plus another surprise coming up. My system has completely changed, new source, Dt diy custom reference speakers as well. I'm just find tuning then let's let it rip.

Edited June 12, 2020 by Sansui77

[Sansui77]

[Sansui77]

I will put up a completely new seperate review comparison on the following, AU-111, Alpha 907 NRA, Alpha 907 Limited plus another backbreaker?????

Edited June 19, 2020 by Sansui77

[Sansui77]

Might have another contender to the list.

[Cafad]

And that would be...???

[Sansui77]

On 19/06/2020 at 6:18 PM, Cafad said:

And that would be...???

Here it is.

Edited June 21, 2020 by Sansui77

[Cafad]

Damn that's a good looking amp!

[Sansui77]

2 hours ago, Cafad said:

Damn that's a good looking amp!

She certainly is Jeff. A real good looker. Out of all the Alphas I have now, she's the heaviest. 

 

It's a shame yourself & @pete_mac are both in different states. Imagine the Sansui gfg that we could have, probably the best Sansui gtg in the world 

[Luc]

Mark that is just a beautiful beautiful thing. Well done. People can keep their ME amps and vintage Jap brands from this era and a whole host of others.

 

These are holy grail amps.

 

Simply superb mate and it's great to see one of these rarities in a home that it'll be well loved.

 

You should come up to the Gold Coast for a holiday and bring a few of your pride and joys to @TerryO 's place and have an ultimate Sansui GTG.

 

 

[Sansui77]

38 minutes ago, Luc said:

Mark that is just a beautiful beautiful thing. Well done. People can keep their ME amps and vintage Jap brands from this era and a whole host of others.

 

These are holy grail amps.

 

Simply superb mate and it's great to see one of these rarities in a home that it'll be well loved.

 

You should come up to the Gold Coast for a holiday and bring a few of your pride and joys to @TerryO 's place and have an ultimate Sansui GTG.

 

 

Would love to come up to a Sansui gtg and meet all you guys in person at some stage when this con19 is all done and dusted. 

 

So what list do we currently have between us all? It's a great list 

 

 

AU-111

907 NRA 

907 Limited 

AU-1111 MOS Vintage

 

@Cafad @pete_mac 

B/C2302

907 DR

907 MR

907 XR

607 NRA II 

 

Did I miss a model?

 

Anyone with a AU-X1 or II?

 

 

Edited June 21, 2020 by Sansui77

[Cafad]

Don't forget Terry's 907 Limited and my 911DG and 907 EXTRA.

 

Also, I know a guy (... who knows a guy, you know the drill) who could add another 3, 907NRA, AU-07 anniversary and one of the 607 mosfets (shame on me, not remembering the model).

 

That potential GTG would last for days, we wouldn't be able to fit in listening time to all the amps otherwise.

[rantan]

Just now, Cafad said:

That potential GTG would last for days, we wouldn't be able to fit in listening time to all the amps otherwise

...and don't forget ,you would need to have a rotating roster of attendees, so that there was always one person at the front door or in the front yard, yelling "Sansui forever"  at passing strangers.

[Cafad]

40 minutes ago, rantan said:

...and don't forget ,you would need to have a rotating roster of attendees, so that there was always one person at the front door or in the front yard, yelling "Sansui forever"  at passing strangers.

I was thinking of a large banner but I'm open to suggestions.

[Sansui77]

1 hour ago, Cafad said:

607 mosfets (shame on me, not remembering the model).

AU-a607 MOS Limited? 

 

[Misternavi]

would be GTG require a BYO step down transformer?

[Cafad]

11 hours ago, Sansui77 said:

AU-a607 MOS Limited? 

 

I believe so yes.

 

6 hours ago, misternavi said:

would be GTG require a BYO step down transformer?

I don't think there would be any need for that, I'm sure some sort of "Step-Down Transformer Menu" could be put together.

[Southie Adam]

On 21/06/2020 at 3:46 PM, Sansui77 said:

Here it is.

Does this have the Tamura transformer?