What would be the 'best' Sansui amplifier for sound quality?

[JimEGR]

At the risk of going further off topic here, yes, these servo subs are pretty amazing. They don't just have a drive signal, they also have a sense signal that can tell what the position of the driver is and apply an electrical brake to slow it. Because it can be slowed so much faster, it can also be accelerated faster without risk of over excursion. Typically you can't accelerate a sub driver too hard because all that mass will have a lot of inertia and you'll lose control of the driver, but this tech solves that. Truly a paradigm shift in subwoofers imo.

And yes, you've hit the reason why I want an AU-X1. Also thanks for the link. The B-2302 is faster but that's even rarer and multiple times more expensive so I'll settle for the "only" 260v/us AU-X1. The maggies are exceptionally fast with a spectral decay that disappears very quickly, I feel an AU-X1 would be a great pair. The Alphas are no slouch either, many of those like the 907MR and 907 Limited are rated at 200v/us, so 77% as fast as the AU-X1. For reference if I went and bought a new pair of $7k Parasound A21+ monoblocks, they would only do 120v/us.

I was also looking at AU-X11 since many say it's an improved AU-X1 but I disagree at least on paper. Unfortunately they added more feedback to that amp, which slows it down since it has to go through that feedback loop before stabilizing. By doing this they dropped distortion from 0.007% to 0.004% but since 0.007% distortion is already so low, I believe this was a poor tradeoff. Sansui themselves even listed the detriments of feedback in the marketing for AU-X1 so I find it strange they backpedaled on that for the AU-X11. I've attached that marketing material.

Great article and information. The AU-X1 vs AU-X11 comparisons and opinions are very interesting to read. Both exquisite machines. I also admire the omission of the tone controls from these units - all business and intended to be listened to as perfectly as is from the engineers ears to ours.

 

[DB-7]

No Tone Controls here, and it sounds incredible:

 

[DB-7]

I also believe the AU-X11 is better than the AU-X1 in terms of sound quality.
Yes, I have several of each and have done comparisons.
The Sansui guys nailed it spot on with the AU-X11

 

[JimEGR]

Her Mighty Majesty!



Anxious for updates on @Bumpalump “cost no object” AU-X1 restoration -

Sansui AU-X1 cost no object project

Waiting for the second X1 arriwal, the goal is to make the restoration using the best components like 1% resistors (maybe Rikens) u-con film capacitors and so on. While it till be winter project non limited with time, this thread will also be full of the information why, how, with full...

audiokarma.org

 

[gammi]

I also believe the AU-X11 is better than the AU-X1 in terms of sound quality.
Yes, I have several of each and have done comparisons.
The Sansui guys nailed it spot on with the AU-X11

As someone considering buying an AU-X1, could you please expand on why you like the AU-X11 better? Sell me and maybe I'll make the switch

Oh and regarding slew rate, it only matters up to a point, in other words if it's fast enough to replicate a 20KHz signal perfectly, making it faster doesn't really do anything. So while the AU-X1 might be faster than the AU-X11, it's possible it doesn't matter.

 

[DB-7]

This is just my opinion and what my ears like, and if I had to choose one over the other, the AU-X11 would be the one.
Both the AU-X1 and the AU-X11 have incredible depth. Even with the volume down low there is the sound of deep power that is hard to explain. Those that have these amps know what I am talking about.

They both are crystal clear, and bring out all the details in the music. The X11 seems a little more dynamic than the X1 at doing it.
The X-11 is also much more balanced in my opinion. What I mean about that is, the bass is just right. Nice and tight , very deep, not too much, not too little, mid range is full, crisp, and detailed. The highs are true to the music and not too bright, and not too dull. The range of sound is only limited to the source.

The AU-X11 offers no fatigue what so ever, because it seems so well balanced musically.
The AU-X1 is a great amp, but if I have to sum it up, seems a bit flat compared to the X11.

MY comparisons were done with my two best unrestored units of the X1 and X11.
Both are in as good condition as one could get.

I recently had one of my X11's exstensively restored and upgraded. That machine is now on a whole different level. Which I wont explain in this thread
I am sure doing the same type of restoration and mods to the X1 would yield similar results. (Which will happen soon)

Best factory sound between the two, in my opinion is the AU-X11.
Maybe @ARGOU will give you his impressions, as he is a big fan of the AU-X11 as well.

 

[gammi]

Konnichiwa! My 907MR just landed from Tokyo. Will be testing with the Holo Audio Cyan 2 DAC in the picture and also trying to bypass the pre-amp and using my Holo Audio Bliss as a pre. Will be comparing to the Van Alstine M225 monoblocks that are also in the picture.

Initial impression just looking at this beast is WOW. What a well built piece of electronics, the knobs look and feel great.

As for the very rough looking circuit on top of the Sansui, that's a converter I built so I can run my STAX SR-X9000 on speaker amps. Haven't made it pretty yet, the circuit is still very "breadboardy"

Edit: Apparently I was mistaken about what the "source power direct" switch does. I had thought this would bypass the pre-amp and make it behave like a power amp, but the volume knob still works no matter what the setting. What is that selector doing?

 

[DB-7]

This is from an old post by @pete_mac , I remember reading when I got my first alpha a907
I dont know if it is basically what your asking, but if anyone would know the answer to your question it's @pete_mac

The power amp direct inputs allow you to use an external preamp or volume controlled source (CD player, DAC etc), with the power amp section of the Sansui.

You can't use the preamp section of the Sansui with an external power amp.

An acquaintance here in Australia mistakenly bought a mint AU-alpha 907 limited as he wanted the option of using it as a preamp to control his active speakers. The design doesn't allow this.

 

[gammi]

This is from an old post by @pete_mac , I remember reading when I got my first alpha a907
I dont know if it is basically what your asking, but if anyone would know the answer to your question it's @pete_mac

Hmm, that's exactly what I thought it would do, let me use an external pre-amp. Yet when I turn it on it's clearly not bypassing the internal pre-amp because the volume knob works on it still. I am using the balanced input, perhaps this only works on RCA?

Anyway, some sound impressions. Something strange is happening I can't recall any amp I've ever had before doing, the timing in some songs feels different. I'll be listening to a song I know very well and suddenly there's a jarring moment where it feels like a note is just slightly shifted in time vs what I normally hear... Some notes hit a little sooner, some hang in the air a little longer, etc. Guess you would call that attack and decay. I'm thinking what the Alpha is presenting is more accurate than what I've heard before.

I was using this song to test for example:

And the sense of presence I got was unmatched, I really feel like I'm standing there in front of her as she sings, more so than with the different timing on other amps, which inclines me to believe the timing on the Alpha is the more correct one. Things like little lip smacks and breaths she does sound unlike I have ever heard before, the timing of them is surreal. I feel like I can almost hear her forming the note before she actually sings it if that makes sense. Like that little bit of pressure build up as she's about to start singing a new line.

Actually thinking about it some more I think it's the differences in timing on the live version vs the studio version, like when she hangs onto a note just a millisecond longer, etc. It's just that I never really was able to pick up on all that so clearly before but the timing on this Alpha is bang on and it stands out now.

 

[pete_mac]

Konnichiwa! My 907MR just landed from Tokyo. Will be testing with the Holo Audio Cyan 2 DAC in the picture and also trying to bypass the pre-amp and using my Holo Audio Bliss as a pre. Will be comparing to the Van Alstine M225 monoblocks that are also in the picture.

Initial impression just looking at this beast is WOW. What a well built piece of electronics, the knobs look and feel great.

As for the very rough looking circuit on top of the Sansui, that's a converter I built so I can run my STAX SR-X9000 on speaker amps. Haven't made it pretty yet, the circuit is still very "breadboardy"

Edit: Apparently I was mistaken about what the "source power direct" switch does. I had thought this would bypass the pre-amp and make it behave like a power amp, but the volume knob still works no matter what the setting. What is that selector doing?

The power amp direct inputs bypass the preamp circuitry but NOT the volume pot - it remains in circuit. If you intend using an external preamp, I’d set the volume control of the Sansui at maximum and go from there. Just be careful if you connect a different source to the amp via a normal line-level input without winding the volume control back down, as serious damage could result!

 

[JimEGR]

Konnichiwa! My 907MR just landed from Tokyo. Will be testing with the Holo Audio Cyan 2 DAC in the picture and also trying to bypass the pre-amp and using my Holo Audio Bliss as a pre. Will be comparing to the Van Alstine M225 monoblocks that are also in the picture.

Initial impression just looking at this beast is WOW. What a well built piece of electronics, the knobs look and feel great.

As for the very rough looking circuit on top of the Sansui, that's a converter I built so I can run my STAX SR-X9000 on speaker amps. Haven't made it pretty yet, the circuit is still very "breadboardy"

Edit: Apparently I was mistaken about what the "source power direct" switch does. I had thought this would bypass the pre-amp and make it behave like a power amp, but the volume knob still works no matter what the setting. What is that selector doing?

Nice! And as you likely already know, comparisons and "good" or "better" SQ is very subjective - ears, room, inputs, speakers etc. And if you are like us, and it sounds like you are, you will need to acquire and hear as many of these rare beauties for yourself as you can - which is the most fun of all. Exploring the Sansui Sound Arc is a fun fun journey to share. Keep sharing!

 

[Sui-Yogi]

This is just my opinion and what my ears like, and if I had to choose one over the other, the AU-X11 would be the one.
Both the AU-X1 and the AU-X11 have incredible depth. Even with the volume down low there is the sound of deep power that is hard to explain. Those that have these amps know what I am talking about.

They both are crystal clear, and bring out all the details in the music. The X11 seems a little more dynamic than the X1 at doing it.
The X-11 is also much more balanced in my opinion. What I mean about that is, the bass is just right. Nice and tight , very deep, not too much, not too little, mid range is full, crisp, and detailed. The highs are true to the music and not too bright, and not too dull. The range of sound is only limited to the source.

The AU-X11 offers no fatigue what so ever, because it seems so well balanced musically.
The AU-X1 is a great amp, but if I have to sum it up, seems a bit flat compared to the X11.

MY comparisons were done with my two best unrestored units of the X1 and X11.
Both are in as good condition as one could get.

I recently had one of my X11's exstensively restored and upgraded. That machine is now on a whole different level. Which I wont explain in this thread
I am sure doing the same type of restoration and mods to the X1 would yield similar results. (Which will happen soon)

Best factory sound between the two, in my opinion is the AU-X11.
Maybe @ARGOU will give you his impressions, as he is a big fan of the AU-X11 as well.

I’m a huge fan of that beast, it’s a gift that keeps on giving from every perspective!
I think DB-7 , Hyperion or Bumpalump is the only people that can form an opinion comparing the two models
AU-X1 Vs AU-X11 , as are the only ones that I know of having seen ,restore and hear both. I haven’t heard the AU-X1 .
For me , if one is going to use a
step-down/up transformer to power up the amp then I can’t see why not having the AU-X11 ,since Sansui claims that it is the upgrade and “problem free” version of the
AU-X1 .

Edit: I don’t think that Sansui ever claimed that the AU-X11 is the upgrade or “problem free” of the AU-X1 , better say that this is an assumption of techs in this forum . Enough for me to call the AU-X11 an upgrade.

 

[Copanel]

Hello, Sansui AU-9500 is the best for me. I really like his sound signature, exactly the fat bass at low volume I was looking for. I use it with Canton karat 200 and Canton CT-1000 speakers.

 

[gammi]

The power amp direct inputs bypass the preamp circuitry but NOT the volume pot - it remains in circuit. If you intend using an external preamp, I’d set the volume control of the Sansui at maximum and go from there. Just be careful if you connect a different source to the amp via a normal line-level input without winding the volume control back down, as serious damage could result!

Ah, this is what I was missing. I assumed since the volume pot still worked, the pre wasn't being bypassed. But it turns out the volume pot is in the path whether the pre is bypassed or not. Thanks!

Nice! And as you likely already know, comparisons and "good" or "better" SQ is very subjective - ears, room, inputs, speakers etc. And if you are like us, and it sounds like you are, you will need to acquire and hear as many of these rare beauties for yourself as you can - which is the most fun of all. Exploring the Sansui Sound arc is a fun fun journey to share. Keep sharing!

Well, I have my 907MR, a 907 Limited I bought will arrive in a few days and I think I'm picking up an AU-X11 this weekend. It seems I dove right into the deep end with these Sansuis!

I’m a huge fan of that beast, it’s a gift that keeps on giving from every perspective!
I think DB-7 , Hyperion or Bumpalump is the only people that can form an opinion comparing the two models
AU-X1 Vs AU-X11 , as are the only ones that I know of having seen ,restore and hear both. I haven’t heard the AU-X1 .

I may be able to count myself among these few eventually. Trying to get an AU-X11 and also a broken AU-X1 to repair. Yeah, I know they're a beast to fix but worst case it can provide some spare parts for the X11.

Enjoying my 907MR a bunch so far btw. Hoping to check the bias on it tomorrow, I just ran it right out of the box since it was listed as working fine, but of course I want to make sure it's within spec.

 

[skippy124]

@gammi the user manual for the 907MR is available on hifiengine if you are currently registered there (they aren’t taking and new memberships). The service manual is also available.

Sansui AU-A907MR Stereo Integrated Amplifier Manual | HiFi Engine

www.hifiengine.com

If you aren’t a member there and want a copy send me a message with your email address and I’ll email a copy.

Cheers
John

 

[Sui-Yogi]

@gammi I have the AU-X11 SM too but I can’t upload to hi fi engine, if you need it, same as above , send me a text with your email and I will forward it to you .

 

[JimEGR]

.....
Anyway, some sound impressions. Something strange is happening I can't recall any amp I've ever had before doing, the timing in some songs feels different. I'll be listening to a song I know very well and suddenly there's a jarring moment where it feels like a note is just slightly shifted in time vs what I normally hear... Some notes hit a little sooner, some hang in the air a little longer, etc. Guess you would call that attack and decay. I'm thinking what the Alpha is presenting is more accurate than what I've heard before.

And the sense of presence I got was unmatched, I really feel like I'm standing there in front of her as she sings, more so than with the different timing on other amps, which inclines me to believe the timing on the Alpha is the more correct one. Things like little lip smacks and breaths she does sound unlike I have ever heard before, the timing of them is surreal. I feel like I can almost hear her forming the note before she actually sings it if that makes sense. Like that little bit of pressure build up as she's about to start singing a new line.

Actually thinking about it some more I think it's the differences in timing on the live version vs the studio version, like when she hangs onto a note just a millisecond longer, etc. It's just that I never really was able to pick up on all that so clearly before but the timing on this Alpha is bang on and it stands out now.

That is THE ALPHA EXPERIENCE. I could feel that Alpha sound just reading your description. Well said. Supernatural. Same music, but on another dimension of articulation. That being said, all the Sansui generations present desirable sound qualities. Not to mention the looks of these works of art. Most "sound" like Valhalla just passively sitting there radiating industrial beauty on the shelf. Desirable attributes on multiple sensory levels!

A few more gems for you to consider -

AU-D11 II -
The highly regarded, first X-Balanced integrated amplifier, which was the foundation for the later Alpha series topology
Nice photos and discussion from @MIJ_Pioneer here -

AU-D11 II

Got a new one in the family :) This one came up for sale locally and seems to be a pretty rare model (at least in USA). Nice copper chassis, toroidal, 130w, loudness, gold RCAs, and some really neat lighting for the input selectors. Came with the matching tuner too! This unit has been...

audiokarma.org

AU-a607 NRA II -
One of the last Alphas. While not as powerful as the 907's, has a refined topology and a dedicated toroidal on the front end.

SANSUI AU - α 607 NRAII Specifications

A great thread from @fojica discussing the evolution and this generation -

Sansui Alpha - debunking NRA series

Ok, so let's say that I'm still in the Christmas giving mood, so this would be a second "gift" :) To start with a bit of history as this seems unclear for some people, Sansui Alpha's were actually born in 1982, with B-2301 power amplifier. Indeed, not named "Alpha" back then, but "X-Balanced"...

audiokarma.org

Some interesting history on the *607* line which seems to be where Sansui launched many design step change campaigns.


And the very last Alpha ever made AU-a607 MOS Limited -

Specifications of SANSUI AU - α 607 MOS Limited

Some good late Alpha discussion here -

Alpha Penultimate / Ultimate : Sansui AU-a607NRA II / Sansui AU-a607 MOS Limited

1999/2000 - The last solid state offerings from Sansui AU-a607 NRA II 80 watts (JDM) (January 1999 - October 1999) 24 registered in the ESAK database AU-a607 MOS Limited 50 watts (JDM) (December 1999 - August 2000) 25 registered in the ESAK database Does anyone know what the final production...

audiokarma.org

 

[gammi]

Thanks for the warm welcome and all the good info everyone.
I just tore open my "new" 907MR to clean it out and bias it. Bias was off pretty significantly, almost double. And there was also a couple hundred mV of DC offset. All fixed now and I would say it made the sound more "effortless". It just flows so easy and smooth now. Idle power dropped about 30W as well.

Went back and listened to the same test track and yeah, the sensation of being there is just unmatched, the timbre is perfect, hand claps sound like hand claps, I can hear the pick on the bass guitar, I can feel the sensation of the brushes on the drum skin, her voice sounds more delicate etc.

Oh and I polished the copper case screws while they were out

 

[peterott]

Yes, an incredible machine. I am still in complete love with my 907MRX. The sound is absolutely stunning. Even if I rotate in the AU-111 soon into my setup in the living room, the 907MRX will stay on "hot standby"

 

[gammi]

Look whose older brother just arrived, 907 Limited. This thing is stunning, I mean polished copper on the underside even? How wonderfully excessive.
Bias was a lot closer on this one, all four were about 35mV and the spec is 28mV. Now drawing about 100W at idle vs the 45W of the 907MR. Those MOSFETS are hungry.

As for sound? I'm struggling to put the difference into words. I feel like the way it presents itself is different. Like it stages a little differently and feels fuller perhaps? That was on headphones (Susvara), on my speakers the thing I noticed was it felt more 3D. I'm not sure which I like better yet.