Preamp suggestions for Atma-Sphere Class D Monoblocks

Great points @atmasphere

I have very short RCA cables & my Mojo 2 source is set to 3 Volts...if I set the Mojo DAC to 1 Volt, the sound softens...so having a source with some balls & a short RCA run could be why I’m not getting the thin lean sound.

Passive has no sound....so when a person says passive sounds like X....X = the natural sound of the power amp & DAC  

@seanheis1 This has not been my experience. Sometimes you can get passives to work great and sometimes you can't. One of the bigger variables are the cables in use. With the higher output impedance passives cause the source to have, there is less control of the cable so its more likely to impart a sound.

The opposite of that is the balanced line system that was developed mostly in the 1950s. This was long before exotic interconnect cables existed yet many of the recordings from this era are spectacular! Obviously the interconnects weren't an issue.

We tried a passive balanced line volume control and found it was not any better than single-ended. Yet when we had a buffer system that drove the balanced lines properly, not only did the system sound better but the differences we were hearing between cables vanished.

To my way of thinking not having to worry about what cable sounds best is a huge boon. That is not available with a passive device.

The other aspect of passive volume controls is the value of the control itself. It will have the least impact on the sound if its a low value, for example 10KOhms, except for the problem of sources not being able to drive such a load properly. So depending on the source, you may have to have a passive that has a much higher value. I find the best place for them is inside an existing amp where the output of the control can be controlled by the designer while insuring that the input is something any source can drive.

 

 

John Stronczer is an absolutely brilliant engineer. Bel Canto just hold back on performance to compete in different market segments. JA stated in Stereophile that the E1x was basically as good as it gets from a measurements perspective. I’ve had other BC DACs in the past and they all have the ability to retrieve detail without being in your face. The other aspect of their Dac/preamps I like is their ability to sound great even at very low volumes.

As I wait for the Atma-Sphere MP-3, I am using a Bel Canto Dac2.8 as a preamp and the sound is nothing short of spectacular - without a doubt the best my system has ever sounded.

Funny you say that.  I demoed a DAC3.5VB in my system (great DAC BTW), and when I used it as a preamp not expecting much I couldn’t tell the difference between it and my Bryston BP6 preamp and was pretty damn shocked by that.  Still, I bet the MP3 is gonna take you to another level entirely and look forward to your thoughts. 

As far as I can tell as a lay person, the advantage of a passive preamp is transparency. With a preamp like the HPA-4 whose performance lies at the limits of measurement devices, this issue is moot.

At any rate, one learns over time that there are no absolutes. Statements like “passives” are better than “actives”, or “Class A” sounds better than “A/AB” are gross simplifications that don’t take into account the complexities of how various pieces in the chain interact with one another, the room and the listener.

After years of searching, I feel I have reached a breakthrough with my current system and I am grateful for that. 

Passive has no sound....so when a person says passive sounds like X....X = the natural sound of the power amp & DAC  

@seanheis1

I’m not a fan of passive preamps. And yes, I’ve had the Freya + in my system with a different power amp. I have also had a full Benchmark stack - dac3b, HPA-4 and AHB2. A quick look at my feedback history here and at USAM will reveal the insane number of pieces I have gone through in the last few years. As I wait for the Atma-Sphere MP-3, I am using a Bel Canto Dac2.8 as a preamp and the sound is nothing short of spectacular - without a doubt the best my system has ever sounded. To my mind, the A-S electronics are my destination. I can see changing my digital source  or speakers down the road but not the amps. That’s how strongly I feel about them.

Seanheis1

I have used two different passive pres in the past, and always felt that something was missing, usually body and dimension. I understand why you might like them, but like everything else, there are trade-offs.

@roxy54 hopefully others get a chance to hear their power amps for what they are...before deciding whether or not to change the sound. 

I love my solid state Van Alstine power amp with a passive pre. The distortion profile of the power amp is just right for me.   

@seanheis1

He already bought Ralph's pre.

1. First, you must hear Ralph's amp with no active preamp to see if you like the sound or if color is needed. 
2. You can do this with the passive Schiit Sys for $50. 
3. If you like what you hear, you can buy a proper pre such as the Benchmark HPA & get the features that you need. 
4. If you are not happy with the sound, then you can start experimenting with active preamps that add second & third harmonic distortion. 

@bcsy

Thanks for your offer to chat! I have already ordered the Atma-Sphere MP-3.

After having experienced just how good Ralph’s class d Mono Blocks are, it was a no-brainer to pair them with a preamplifier of his design .

 

Greetings,  I’ve had the Aesthetix preamp for a couple years with an Aesthetix amp.  Currently have a Supratek Cabernet under evaluation.  Happy to chat if you like.  Thanks. 
Brian

Congrats.  You’re in for a real treat.  I use a MP-3 with both an A-S S30 and Class D amps.  It’s a wonderful combination that you would be hard pressed to better unless spending considerably more $$$.  Your Totems (which I also have owned) will really shine.

@soix, @vthokie83. Thank you, I will try and update my experience here once its all settled in.

@hifinut, thanks for sharing your experience. I am glad I arrived at the right decision eventually!

 

To quote from @acresverde:

The fact that you will simultaneously establish a relationship with one of the most knowledgeable, caring and responsive bunch of guys in all of audio and will be buying American is just the cherry on top.

As my daughters might say - Word.

I did this in reverse order.  I bought an Atma-sphere MP3 Mk 3.3 first.

Then I replaced my push pull tube amp with Atma-sphere Class D mono amps.

The combo is fabulous .  I am very happy!!

My favorite preamp is Burmester! All amazing quality. 
I also like ones made by The Gryphon 

srama

Congratulations on the new purchase, let us know how it goes when you get it all set up and going

Congrats and enjoy!

@acresverde 

High praise indeed! I value your personal experience hearing the MP-3 in your friend’s system. I just placed an order for an MP-3 with the V-CAP and chassis damping upgrades - to say I’m delirious with anticipation is understating it!

 

@  srama    I have owned the A-S MP-1 for 20 years and just got it back from being upgraded to 3.3 status. Ralph finally got me to agree to it after 10 years of subtle persuasion. All this time it has been paired with his M60s. A friend of mine has the MP-3 (not upgraded) paired with MA-1s and I have been listening to it routinely for at least 10 years and have had it in my system a few times. I am here to tell you that the MP-3 is fully 90% (maybe more) of what my preamp is sonically and requires only about half the tube complement mine requires. It is truly balanced and  represents one of THE great hifi bargains in preamps. Buy it and don't look back. The fact that you will simultaneously establish a relationship with one of the most knowledgeable, caring and responsive bunch of guys in all of audio and will be buying American is just the cherry on top. Enjoy!

@ddgtt, thanks for your suggestion. Going by their reputation alone, I have no doubt about its brilliance - unfortunately, it is more than twice my budget :)

Thanks everyone for your suggestions and engaging discussion. I have decided to go with the Atma-Sphere MP3. I received my A-S class D mono blocks yesterday and I am so smitten by them that it is, in my mind, a no-brainer to pair it with a preamp from the same designer. You can see my gushing impression of the Class D’s here:

https://forum.audiogon.com/discussions/atma-sphere-class-d-amazing?page=15

 

The best pre-amp I've heard for use with the Atma-Sphere class D monoblocks or any class D amplifier is the Mola Mola Makua.  You can get it as just a line-stage type preamp or you can get with a built-in DAC (same as the famous Tambaqui) and/or a built-in phono stage (same as the Lupe).

@srama Yes, for some reason Jensen does not list a 'XLR in, RCA out' subwoofer transformer, but they will provide them!

@atmasphere

Thank you, so it sounds like I can hook up my existing phono preamp to the Monitor 1 or 2 input on the "basic" line stage version.

Understood, connecting a sub will require a Jensen transformer - a quick search did not reveal any xlr in /rca out versions either at the Jensen website or at resellers, but I will look for it when the time comes. Of course, if you have a known source for this item, please do share!

I currently have a single REL S/10 with speaker level connections; however, I won’t be able to do that with the new Class D monos, since the single connector cable will not reach the two sides of the cabinet the amps will be placed in.

BTW, FedEx informs me that the amps were just delivered! Excited to hook them up as soon as I have a few minutes off from my endless day of meetings :)

I just realized that the MP-3 comes with ONLY balanced inputs. My external phono stage only has single ended outputs - can I use a simple rca to xlr cable or do I have to select the version with optional single ended inputs?

Also, does the preamp support connection of a subwoofer through one of its outputs?

@srama The MP-3 like the MP-1 has two single-ended inputs, Monitor 1 and Monitor 2.

You can also order it as a line stage only or with its balanced phono section which works with LOMC cartridges. So the phono input is balanced and the EQ is handled in the differential domain so as tubes age the EQ stays rock solid on the curve.

There are dual balanced outputs. I use the second set to drive a set of Jensen subwoofer transformers that convert from balanced to single-ended for my subwoofer amp. The Jensen transformers are optimized for low frequency operation so unlike most transformers, do not rob the bottom end of any impact or extension.

@atmasphere, I just realized that the MP-3 comes with ONLY balanced inputs. My external phono stage only has single ended outputs - can I use a simple rca to xlr cable or do I have to select the version with optional single ended inputs?

Also, does the preamp support connection of a subwoofer through one of its outputs?

 

 

 

 

I second the Audio GD HE-1 XLR....10 tubes...it’s own regenerative power supply to optimize the current from the wall plug...nothing under 10K can touch it for soundstage....musicality...life like imaging and just plain sweet with my Class D Amps. Aavik and Peachtree. Call wally @ underwood hi-fi. $4500...a steal in Hi End!

The MP-3 has no problem driving the class D to clipping, if that's what you mean. It supports +4dBm which is far more Voltage than most power amps need.

Thank you, that's all I needed to know!

@srama The MP-3 has no problem driving the class D to clipping, if that's what you mean. It supports +4dBm which is far more Voltage than most power amps need.

In practice the 6SN7s of the line stage hold up quite well- we rarely replace them in warranty (which is a year on tubes).

@atmasphere, Thank you, that is good to know.

To reference @avanti1960’s post above, I assume there will be sufficient gain between the MP-3 and the Class D to power my speakers (Totem Acoustic Forest Signatures)? I certainly don't want to end up with restrained dynamics or the sense that the music is somehow being strangled.

 

 

One thing I noticed in comparison to the other two amps under discussion is the significantly larger number of tubes in the MP-3 - is this because it is the only truly balanced preamplifier is this set? Does this have any implications on maintenance, require more frequent changes to an entire complement of tubes, etc.?

@srama The tube complement depends on whether the phono section is included or not- the line stage uses four tubes. There are more tubes because its fully differential. In practice the 6SN7s of the line stage hold up quite well- we rarely replace them in warranty (which is a year on tubes). The phono section works with LOMC.

@srama, of course but to me more gain does improve the energy and dynamics. no need for the ultimate upgrade, just get some nos sylvania down the road.

The SLP 05 is now on sale at cary direct for $5997 !

 

https://carydirect.com/shop-now/preamplifiers/slp-05.html 

 

@avanti1960, thanks for your comment. I did notice the low gain on the A-S class D (compared to the 27 dB on my Bel Canto Ref501S). I can see how the high gain in the Cary can help offset the low gain in the A-S. I would think, however, that the MP-3 would drive the class Ds effectively given they are both from the same designer?

That said, the SLP-05 is hugely attractive - both aesthetically as well as based on the specs. I just don't want to spend close to $8K at its current sale price for the ultimate version, and I'm not crazy about purchasing tube gear that is several years old.

 

@srama

The atma sphere monos have unusually low gain for an amplifier (22db)  compared to most that typically have 29 or 30 db gain.  

much like my Pass Labs XA 25 amp that has 20 db gain, they really match well with preamps that have higher than typical gain.  
My Cary SLP 05 has that with a 24 db low noise gain stage with balanced connections.  It matched amazingly well with the Pass amp and should do just as well with the atma spheres.  The SLP 05 does create a smooth holographic atmo sphere of its own in addition to be excitingly dynamic.  Get the 05. 

@atmasphere, thank you so much for your detailed response. I cannot claim to understand all the details, but I think I'm following in broad strokes. One thing I noticed in comparison to the other two amps under discussion is the significantly larger number of tubes in the MP-3 - is this because it is the only truly balanced preamplifier is this set? Does this have any implications on maintenance, require more frequent changes to an entire complement of tubes, etc.?

Just to clarify, I don't intend to  jump into the rabbit hole of constant tube rolling - my limited experience with doing this in the past caused more stress than anything else! I'm only concerned with long-term reliability and cost of ownership. 

+1 Aric Audio Motherlode XL. I have used this combination in my refernce system and it sounded superb.

I understand if you would rather not do so in a public forum, but it would be great to hear your engineer’s perspective on the Spatial Raven and the Backert Labs Rhumba, and how the MP3 differs from these designs (or provide some links if you have already discussed this).

@srama There are two main differences. The first you already know about- the MP-1 and MP-3 employ a balanced direct-coupled tube output, which allows it to be very transparent. Usually in most preamps the output coupling cap defines the low frequency cutoff and also causes the output impedance to increase as the frequency goes down. When you direct-couple, the low frequency cutoff is defined by coupling caps prior to the output and so are much smaller in value (typically by 2 orders of magnitude) which allows them to be more transparent and the output impedance with respect to frequency is a ruler flat line across the audio band, something you can't do with coupling caps and very hard to do with output transformers.

To my understanding the Spatial uses an output transformer. Personally I think if you can eliminate the transformer the circuit will be lower distortion and wider bandwidth. Transformers unavoidably introduce distortion due to the hysteresis loop that is always present (although minimized in good designs).

As best I can make out, the other difference is that in addition to being fully balanced, the MP-1 and MP-3 are also fully differential. This allows a lower parts count, lower noise (in theory up to 6dB per stage of gain) and lower distortion although the distortion difference as opposed to a non-differential balanced circuit is fairly small.

Not having heard the Spatial or Rhumba I can’t comment on the sound (which by all accounts is excellent), but what I would expect (as this has played out in other comparisons over the last 35 years) is the use of the direct coupled output is immediately obvious in terms of transparency and bandwidth (the latter best heard in the bass region- the deeper your speakers go, the more obvious this becomes).

Not having an output transformer also means the preamp is less critical of the interconnect cable used between it and the amplifier. Transformers are inductors and cables have capacitance, put the two together and there will be a resonance at some (usually ultrasonic) frequency. Not having the numbers available (such as the inductance of the transformer presented to the cable) its hard to know what frequency, but I noticed that the designer recommends avoiding higher capacitance interconnect, so I’m sure he’s aware of this issue.

Srama,

Between the LS-100 and the MP-3 I thought soundstage and realism were roughly equal, but I definitely preferred the tonality of the MP-3, which is likely due to the reasons Ralph outlines above. One other variable is that the LS-100 is tube rectified and the rectifier has a definite effect on the sonics. I ended up liking the 5U4GB much more than the stock 5AR4. The MP-3 is solid state rectified and eliminates that variable.

I failed to mention before that I also owned a Don Sachs DS2, sort of the forerunner to the Raven. It was terrific in its own right but more romantic than the LS100. I owned them at the same time and slightly preferred the LS-100, but if the Raven is as much better than the DS2 as most (including Don Sachs himself, who should know) are saying, that probably changes the equation.

@atmasphere, thank you for clarifying regarding the remote as well as the additional insight into the design.

I understand if you would rather not do so in a public forum, but it would be great to hear your engineer’s perspective on the Spatial Raven and the Backert Labs Rhumba, and how the MP3 differs from these designs (or provide some links if you have already discussed this).

It is definitely on my short list, as long as remote capability is available.

@srama The remote is an option (no charge); scroll down and you'll see it.

http://www.atma-sphere.com/en/mp-3.html

Decades ago when we developed the MP-1, part of that was figuring out how to do a balanced direct-coupled output which had to support the balanced line standard. We did that and have obtained two patents on the process. Before that, there were only two ways to support the standard; one is to use and output transformer and the other is a solid state circuit that can float and sink current at the same time (today there are semiconductor companies that make chips for this purpose). We patented a 3rd method.

In a traditional tube preamp, the biggest impediment to transparency and bandwidth (which includes the ability to cast a proper soundstage) is often the output coupling capacitor, which has to be large enough in value to allow the preamp to play bass when driving the lower input impedances of a solid state amp. That all goes away when you direct-couple and its the sort of thing that's immediately apparent.

 

 

I own a CarySLP 05 with ultimate upgrade. Bought it used a few years ago in pristine condition for $4300. It has a decent headphone amp. I’ve had great fun tube rolling and my current setup uses Raytheon VT231’s in the gain stages and CBS Hytron 5692’s in the buffer positions. I have a variety of VT231 and 5692 tubes to play with and it is fun to optimize certain characteristics (for example, Ken-Rad VT-231’s seem to have the most solid bass while still being creamy in the highs, while Sylvania seem to have a bit of sparkle in the highs, with this being heard from VT-231’s to NOS 6SN7 GTB’s from the 1960’s. 
 

Tube rolling doesn’t have to be expensive- I really like the NOS Sylvania GTB’s from the 1960’s that I bought at $35 matched each from Brent Jessee, enjoying them far more New Sensor Electroharmonix tubes.

 

 I have really enjoyed this preamp. Tremendous imaging with well-resolved holographic instrument placement, very quiet with black backgrounds, tremendous sense of dynamics and inner detail. Make sure to use a high quality rectifier tube!

 

So many great suggestions, thank you all! 

As @acman3, @armstrod and others have mentioned, the A-S MP-3 is a recurring theme, which is understandable, given the amp it will be paired with. It is definitely on my short list, as long as remote capability is available. Does anyone have comments on their ability to cast a holographic soundstage, realism and tonality?

Backert Labs gets a lot of love here on AudioGon forums as well. Interestingly, I met Bob Backert many years ago (at that time he lived about 25 minutes from where I am, in PA) when the seller of a Musical Fidelity preamp I bought on AudioGon recommended him to fix a problem with it. He impressed me as highly knowledgeable and as a modest, soft-spoken gentleman. I have no doubt that his products are outstanding. However, all except for the "base" Rhumba 1.4 are outside what I want to spend at the moment. Which, of course, may be all I need.

The LTA microzotl sounds great on paper, but probably not the best match for the A-S monos as it does not have balanced outputs. 

@osiris369, I am a fan of the BluOS platform as well and have owned many of their offerings - M10, C389(?) and was initially considering a comprehensive solution such as the M66 or the Bryston BR-20. I have decided ultimately to keep streaming and dac functions separate (as they change the most often) and focus on purchasing a pure analog preamp which is capable of sprinkling a little "magic" into the system.

@rmdmoore, thanks for the +1 for the Modwright LS100 - it is very appealing, especially at used prices. If I understand correctly, however, it is not a true balanced design so I don't know whether I will be losing something with the A-S monos?

As it stands, the A-S MP-3 and the Spatial Raven are tied at the top. It's great to have multiple options! Thanks again to everyone for your much valued opinions. 

A bit off-topic but I thought it important to mention that running a single REL sub with monoblocks and, separately, class D amps takes special care. I could not successfully configure a single REL sub with my BAT monoblocks. Had to use 2 subs. I was using the Speakon connector. 

Audio Mirror Wave. Vlad is very easy to work with and he just added sub out. This may suit your needs.

https://www.stereotimes.com/post/audio-mirror-wave-tube-preamplifier-by-terry-london/

https://forum.audiogon.com/discussions/audio-mirror-wave-tube-based-line-stage-is-one-of-stereotimes-2023-most

As a general fan of the BluOS platform, I'd lean toward the NAD M66 (assuming streaming will be a routine). 

But I also say proceed with caution and do a lot of research before hand. NAD failed spectacularly with the initial release of the C658 streaming preamp. It has most of the same bells & whistles as the M66. But the integration of DIRAC did not go so well. I'm not sure if it was a software problem or hardware problem. Looking at recent reviews it still has not been 100% resolved. The annoying part is that NAD & Bluesound both blamed the other and took no responsibility to make things right with the customer.

 

So again - proceed with caution. Only purchase from a retailer that has stellar customer service, and doesn't hassle you if you want to make a return.  

 

As others have mentioned, you'd surely do well with a matching Atma-Sphere preamp. But as others have mentioned, there are other options also. I have a pair of MA-1s and use a ModWright LS100 and it sounds sublime. It's not fully balanced but does have xlr outputs. I've spoken with Dan at ModWright and he is willing to add a balanced transformer which I'll probably do at some point. The ls100 can usually be found on the used market for a song. I feel like the ModWright gear is under appreciated for sure and it pairs beautifully with Atma-Sphere 

I have the Atma-Sphere Class Ds and run them with Ralph's MP-3 3.3, a great combo as you would expect. I bought mine without remote and Ralph was able to retrofit it with no problem.

I previously owned a Modwright LS-100 and ran it with a pair of Atma-Sphere M-60s, but sold it before the M-60s were replaced by the Class Ds. It's a terrific preamp and sounded great with a lot of amps, but I thought the MP-3 had better inner detail and benefitted from being fully balanced.

The preamp I've kept as my one spare is an LTA MZ2, which I believe is an incredible bargain. I can only imagine the LTA MicroZotl is even better, just as the Atma MP-1 is likely better than the MP-3. It all depends on how much money you want to spend.   :-)

Srama, I  have the Atma-Sphere Mp-3 with the Atma-Sphere D amplifiers. Very good together.  I like the phono amp a lot. I have not heard any of the preamps on your list.

Good Luck!

+1  Backert Rhumba Extreme or Rhythm. All of the Backert preamps are sensational. The sound is neutral but absolutely magical. I have the Rhythm (flagship model) and I use 300B mono blocks or a Pass Labs XA 30.8. In either case the Backert preamp has proven to be an end game pre for me. I would suggest going to their website and reading all of the information about them. Great company and a superlative piece of gear.