ack's system - end of round 1

Are exposed tonearm wires susceptible to noise pick up?

In a recent post elsewhere here, bare tonearm wires were shown going from the cartridge over the armwand, somewhere out back, and I contended that this runs the risk of exposing them to noise pick up. In fact, in my own VPI arm, the tail end of the wires is also out in the wild, before ending up up in a junction box, and so are Basis' own Super Arm's (see below). The difference between my wires and Basis' is that I have a single cable with 5 wires in it, which means the ground wraps the others to some degree, and in Basis' case, there are separate in a 2+2+1 configuration, which tells me the signal wires are more exposed than mine.

Is this a problem? Well, simply squeezing my exposed wires with my hand picks up hum (not just touching, but squeezing the entire cable). So would anyone believe that the concoction below with the copper shield actually yielded quite significant improvements? There have always been certain piano and violin treble notes which sounded a bit more pronounced than others, and I couldn't figure out why (keep in mind my panel's frequency response is virtually flat); the problem was really evident with many instruments in the same region, so I had to accept it as a fault... this shield has ameliorated this problem and improved the overall sound quite a bit; and it also strengthens my aversion for non-metallic armwands of any kind, or any arm that exposes wires more than necessary...

I am curious what others think and what their experiences have been.

Here's my experimental concoction to shield the cable underneath it (cable not touching the shield), while I am looking for ways to turn it into a proper copper (pipe?) conduit...



And here's Basis' own Super Arm :

0.42 ohms - or why crossover tuning is a fine art

First of all, a few weeks ago I thanked quite a few people for helping out in this thread, and I grossly missed two important members, LL21 and anrdomedaaudio. Sorry guys, and indeed, my most sincerest thanks!

So in this segment, perhaps I can also help by raising an important issue in speaker design, that of fine tuning the crossover. As I've said in the past, I have the deepest respect for designers like Wilson who enable users to do their own fine-tuning of tonal balance and phase, regardless of potentially opening up a Pandora's box for them.

So... 0.42 ohms... does this really mean anything??? For the last 5+ years, I've been tinkering with the bass part of my crossover, with the last 6 months being really intense and tiring. I got to the point of being able to pinpoint differences down to 0.1ohm increments, and to make a long story short, I experimented with various values from 0.0 to 2.0 ohms in the woofer section (and I have two woofers); eventually, I nailed it down to between 0.40 to 0.45 ohms in the last couple of weeks, settling on 0.42 in series with both woofers for best results, while adding another 1.8ohms to the rear woofer (it's a 4-ohm nominal impedance). To complicate things even more, I have a sub to blend in as well. The numbers mean nothing to any one of you, but the painstaking process of getting there and results achieved should.

It has been a torturous, arduous, frustrating and rather insane process - and I must have spent over 1000 hours on it - but at the same time, I now have great appreciation for those few speaker manufacturers who spend months simulating, listening, adjusting, and sweating all the small stuff for better sound, as well as all of us who make similar efforts to adjust our speakers in our rooms. The whole thing is really an art in itself.

Here's the end result: when the bass is as best as it can be, timpani, bass drums and other similar percussion are quite significantly clearer and more articulate and impactful; bass strings, like contrabass and cellos, have more texture and better microdynamics; a piano's lower registers take on that important metallic nature as well... etc. Depending on the crossover slope, the effect can be heard all the way into the treble - crazy! To get to this point, one must either have nerves of steel, or be on Prozac, so you've been forewarned. If I were to do it all over again, I would simply start and focus on human voice first.

Finally, I would not be able to do any of that without these incredibly neutral, ultra-clean and accurate Spectral amplification electronics - the Spectral Lab, as I have called it before... Such enviable ears and engineering prowess some people have!

Thanks again!

The 30SV's balanced input module, for digital components

The last few years have been eye opening for me with all the modifications and tweaks I've been making, which I intend to summarize in a few weeks. Meantime, here comes another eye popping experience with digital. I like the heights to which I have taken my Alpha DAC, but I've felt lately it came at a cost in somewhat hotter treble than I wanted, and perhaps higher resolution came together with higher distortion in the midrange and treble area or even ultra high frequency noise, evident at crescendos and loud passages, with a sound that would be best described as somewhat shriek or slightly etched... or even an accentuated leading edge.

After having spent 8 hours today sitting within a full youth symphonic orchestra, the overwhelming sound all around me got me thinking. So, as I was about to sit down and design a filter between the DAC and the preamp, it dawned on me that the 30SV has a balanced input claimed to be designed specifically for digital components. I had to try it... but first, here's their language from the bulletin http://spectralaudio.com/bulletins/NL-0115.pdf:

The Missing Link

With the widespread use of integrated circuit op-amp topologies in current high-end digital processors and digital source components, the role of the preamplifier to optimize the component interface has never been more critical to final system performance. Todays digital converters have a challenging task delivering precision conversions of music files and downloads while also driving complex cables and low-impedance input loads utilizing rudimentary analog circuits and basic power supplies. Without the benefits of discrete,high-bias analog amplifiers, digital processors struggleto provide optimal drive and load isolation when facedwith the full dynamics of high-resolution recordings.In addition to these output drive limitations, IC baseddigital processors require balanced output operation toavoid higher distortion levels which occur when usedsingle-ended. It is also important to recognize thatdigital audio processors are not equipped to performthe role of preamplifier in high-end audio componentsystems. Power amplifiers require robust drive cap-abilities from the best discrete class Apreamplifierline sections to avoid impedance mismatching, currentlimiting and cable reflection problems associated withlow bias IC op-amp output sections.

The Model 304 Balanced Input Amplifier

To address the shortcomings inherent in the outputsections of todays high-end digital processors, Spectralengineers have developed the model 304 balanced inputamplifier. The model 304 is a discrete, high-speedclass A unity gain buffer operating on unusually highvoltage rails. This fully push-pull topology is derivedfrom our innovative SDR-4000 I/V balanced amplifierand features superior performance to any IC buffer.The model 304 is design optimized as a discretebuffer amplifier unlike conventional IC input buffers.Custom discrete buffers are a rarity in audio todaybut still are found in the best ultra-premium recordingconsoles. Although difficult to design and hugelyexpensive compared to op-amps, the optimized discreteinput buffer is the only uncompromised solution forinterfacing digital audio components and amplifiers.Spectral engineers have taken the discrete input bufferto the next level in the 304 balanced input amplifier.Custom matched J-fet transistors are employed in the cascode front-end. Built to Spectral specifications forlow gain applications, the handbuilt devices lowercrossover distortion, noise and improve common moderejection. Bandwidth, slew rate and distortion are allvastly superior to conventional buffers. The speed andresolution of the 304 balanced input buffer are exem-plary and perfectly compliment the superlative perfor-mance of the new G3 line section of the DMC-30SV.

Click to expand...

I would read the above very carefully, because some beautiful mind(s) spent a lot of time thinking about all this and came up with a solution. I was at first apprehensive, thinking that resolution would drop, but alas, resolution and clarity actually increased, as if the noise floor dropped yet again and the sound became even clearer. Moreover, the typical missing body from digital that I hear just about everywhere came right at me, at least to the degree that these speakers can project.

When I dropped my usual Mahler 2nd with the BSO/Ozawa, my jaw dropped at the clarity of the subtle triangles I've talked about before, the added orchestral weight, and overall clearer timbre. WHY THE F* DID I NOT DO THIS BEFORE. Distortion from this digital is now so low that I can max out the preamp, where I used to never go above 80% or so. This is serious stuff, and the reason why I am usually glowing when I write about Spectral. These are REALLY serious electronics from the beautiful mind of Keith Johnson and everyone else involved. More than ever, I want to get those DMA-500 amps.

Now here's the real kicker - I was using this balanced input for my phono for years, and it wasn't working well; in fact, resolution went up when I switched to a true RCA in for my phono. With the Alpha, I am getting the exact opposite result. (Unfortunately, I've told a couple of people before not to use the XLR-in, based on my experience with the phono - my apologies). Timbre is so much closer to what I heard today sitting with the orchestra, and this is a good place to be. I happened to be sitting next to the timpani and French horns, and though I have yet to hear such clear timpani in any system as the real thing, I am in a better position at home than before. Regarding the overall treble output from the symphonic orchestra itself today, it was a rehearsal in a very large room, and the treated walls plus sheer body count absorbed a lot of it. One thing is for sure: what the musicians and conductor hear is NOT what we hear as spectators in a hall, any hall. And rehearsals do sound different than the actual performance in a large open hall.

High end audio is a fascinating hobby as we all know, and this is just one more item in the pantheon of beautiful sounds. Hats off yet again to Spectral! We now have a preamp that fixes digital, if you can believe that. This in itself raises some interesting questions... to be continued...

Day 2 with the youth symphony orchestra - the “real” thing

Performance day and sitting balcony front row and orchestra 10 rows back in the concert hall, the sound is quite different than on stage with the orchestra during rehearsals. Gone is the timpani presence and impact, the bells barely audible, snare drum quite soft, more string presence and body, the cellos resonating the same way. The sound has a lot of body and is very midrangy.

This is all proves to me yet again that what we spectators hear is not the same as what the musicians hear, or what the microphones may pick up. Or as we’ve said before, which version of a live performance are we using as a reference?

Therefore, all we have is the recording and memories of what each instrument should sound like. The rest is all relative. From this point of view, all I care to reproduce is the recording, and for the real thing, I know where to go. And to reproduce a recording I need timbre and articulation - and that’s why I use that as the goal of this system, on post #1. It’s more important to enjoy the music than to get bogged down in endless debates...

The point I was making is all about how the sound changes on-stage vs off-stage (and where off-stage), and that one cannot predict what the mic will pick up which usually sits on-stage (so how can one predictably shape a system to sound the way one perceives sound off-stage, and do so for every recording with a fixed system configuration). To give you another example, after my son's own participation in the orchestra was over, he got to listen to Part 2 from the balcony next to me. Untrained he is yet for sure, but nonetheless, he turns to me and says: "your recordings sound better" [he was commenting on the Carmen piece they were playing]. Asked to elaborate, he could not stand the lack of treble information - practically what I also wrote above. When I told him that we have nowhere near the body of the orchestra at home, he agreed and added: "but this is not what I hear on stage." Well, I know what he meant

Sitting with the orchestra - a mini video documentary

Here's a video from sitting with the youth symphony orchestra during the rehearsals the other day, to get a feel of what it sounds like. As I am sitting next to the French horns and close to percussion, notice how their sound overpowers everything else; then, when the contrabasses (in the opposite side) play solo, they can be very easily heard, but when the orchestra goes full bore, I hear less of them; ditto later on with the cellos (not shown). I believe I have another video of solo timpani, and may post it later on.

The sound is not very clear, but the violins in front of me have a lot of treble energy, but I suspect the iPhone cannot capture that correctly. These soundrooms, just like concert halls, are voiced like everything else, and they are designed to absorb treble energy, otherwise, all this energy would be overwhelming. One of the things that makes the Boston Symphony Hall so great sounding is how it's been itself voiced, and it actually preserves a lot of the treble energy (other halls I've been to are downright plain dead.) Still, the differences between an open rehearsal (very few people in the audience) and a regular performance (room filled, more absorption) - while sitting in the same place - is quite noticeable.

Finally, since Ron started a thread about what a conductor does, here's an excellent example of how she plays the musicians, telling them how to interpret/play the score, and where to put the emphases on.

Enjoy

Al M. said:

Very cool to watch! Thanks, Ack. What is the piece that they are playing?

Click to expand...

Aethelinda [Welsh for Dragon] by Jeffrey Bishop https://www.youtube.com/watch?v=RVjrwIggSGQ

The conductor was SO much into it, a real star, and she came from the Lexington public school. One of those subtle things a conductor, like her, will do is even pick the mallets for the gong (went through three kinds), and surprisingly, she even chose real hammers for the metallic xylophone, like you'll hear in this video

MadFloyd said:

That was VERY cool. What instrument does your son play?

Click to expand...

He plays the euphonium, aka baritone horn, in the orchestra; and also guitar and piano here and there. His friend across the street plays the violin and sometimes we have both give us demos in here. The euphonium easily overpowers my room

The 30SV's balanced input module, for digital components - PART 2

I am starting this segment with a teaser: are we ever going to see that rumored Spectral (two-chassis?) super preamp???? And what about that phono.

Regarding this balanced input module: I am still gathering all my thoughts and observations, so that'll have to wait a bit, but this digital sounds even more detailed than ever, without etch, and all the treble energy that I am looking for, only cleaner. More than that, the level of vividness and clarity has gone up a number of notches, to the point that the Proteus7 Dorian CD - aka James Bond, as we call it over there - is SCARY to listen to; the dynamics from CD are unlike anything I've had in here before. Bottom end to die for. Presence, oh...

I don't know what they have done with this module and what they know about digital, but I don't really care, though I have to admit I am really curious. The interesting thing is that I am only running the DAC with RCA-to-XLR adapters to the preamp, as I have not modified the separate balanced-out section of the Alpha. So it's not common-mode rejection type of sonic improvement.

At first, I thought this module might be an equalizer of sorts, but no, everything just sounds clearer, more vivid and in control, with more detail, rhythm, three-dimensionality body and dynamics, and no etch - nothing euphonic. I don't think I have used the word 'Wow' ever before for digital, and I think I am getting there. Meantime, I am more convinced than ever before that, not only DACs cannot _properly_ drive amps directly, the DAC-preamp interface appears to be fairly critical, at least in my context.

Perhaps equally important is that it's easy to demonstrate in an A/B the differences between connecting the DAC into any other input and then to this balanced module, with the same cables, while compensating for gain differences (the balanced module has less gain).

The 30SV's balanced input module, for digital components - The Verdict

Thanks Dan. Well, it surely is a good thing to be away from one's system for some time, to only come back and instantly verify things one more time, as I am about to describe.

To start, this balanced module is one hell of an engineering marvel - a must-try for 30SV owners. As I wrote before, at first, I was apprehensive about what it does - an equalizer perhaps - but no, this is really serious engineering.

Next, some interesting data points:

a) There is a ~9-10dB drop in gain when I plug my DAC into the module (measured with a 1kHz tone); that surely got me suspicious... but just today, I plugged in my tuner whose preamp input is already attenuated internally by ~10dB through a dedicated switch inside the preamp. So I kept one channel in the existing input and plugged the other in the balanced-in module - the gain difference was roughly 0.5dB or less

b) then, with the mono switch on the tuner turned on, I flipped between inputs. Hardly a noticeable difference, though the balanced-in was ever so slightly better, and nowhere near the drastic differences I hear with the DAC going through this balanced module - how cool is that! That had me thinking, this is no equalizer module... great. I still cannot explain why the phono plugged into that module didn't work well in the long past, but I may be not remembering correctly; and didn't care to experiment again

c) the bass region seems a little diminished with the DAC plugged into the module, but this only enabled me to turn up the subwoofer, which both the phono and tuner also needed - another win

So what is this module??? A current amplifier? The DAC certainly has plenty of voltage output but only 1mA at max gain. The tuner has a discrete output section. I don't know what it is, but I can tell what it does, and it's a sensational result. While away from the system, it dawned on me that this module gives me everything I ever wanted while experimenting with the DAC's built-in volume control for months on end, as I have written in these pages before. Certain volume settings on the DAC would offer smoother sound, but less resolving and perhaps a little polite; others would provide the brio, but also be aggressive. I struggled for a long time to find a good compromise, but a compromise it was. My local friends grew tired and confused about which volume setting I had "finally" settled on in the DAC...

Another problem I struggled with the DAC was lack of 3D dimensionality, offering instead more of a 2D presentation than anything else; and the last issue was some treble harshness with certain volume settings. So once more, to hell with built-in digital volume controls in DACs, they are one of the worst things that ever happened to digital, and bravo to those who eschew it (MBL being the latest, as I read in the Stereophile review of the N31 player/DAC).

The sonic impact of running this DAC through this balanced-in module is as I have written before: more vividness, even more resolution, a totally 3D soundstage, no treble harshness, and overall, a sound that is smooth and in total control, with body, brio and presence, assuming the DAC is up to all that. And oh, the human voices! Incredible, if you ask me. This DAC/module combination fit like a glove. Our friend Al M introduced us to a Stockhausen CD with sensational piano piano pieces, and one of the tracks is a chromatic scale for testing - well, now THIS sounds more like a real piano than ever before, with all the power and presence. Really impressive. Thanks Al! And after settling on a digital volume setting of 53.5 on the DAC, there isn't a single CD that hasn't caused me to jump up with excitement. Given all this, I cannot fault those who write that digital lacks body and sounds thin; but it appears it's all in the DAC's implementation including the analog output section.

Just to give another interesting data point, I've demonstrated a Paganini Dorian CD for strings and guitar to folks who have visited me, and we all agreed that the violin sounded rather weird, if not downright fake, and it's been like that for as long I can remember, over two decades. Well, it now sounds oh so right - how do you explain that. I also noticed how much better castanets sound, something that has bothered me in the past with just too much of a leading edge and unnatural treble information.

Next, now having a smoother treble from the DAC, I was wondering if I can do something about my analog as well. So I dropped the arm by 2mm, something I've been meaning to do for a long time, and re-set VTF and alignment. Et voila, another significant gain in smoothness. Effectively, SRA/VTA must have been off, and the higher the system resolution went, the easier it became to pick up faults with this analog.

To close this little chapter, this balanced-in module is something to be reckoned with. I strongly suspect it compensates for lack of current in source components to properly drive even a preamp with a typical 15K input impedance, and/or perhaps it removes UHF noise, but I could be totally wrong. However it does it, I can only say to other 30SV owners, just plug in your own DAC is see what you think. I have a feeling your jaw will drop. I've personally never been so excited about digital.

Is there ever enough resolution? The DMA-500AR & Magico M3 again

So I am actually really disappointed... apparently, our recordings have an exceptionally high level of detail captured, so why can't we have equipment of equal quality as the recording studios' to reproduce that, that doesn't cost an arm and a leg?

Case in point, my latest, loooong audition of the latest all-SV Spectral system driving the Magico M3s. I may not have liked the euphonic midrange and lack of deep bass as I wrote elsewhere, but in terms of resolution of detail, I have not heard anything like that to date. While playing my Mahler 2nd, I clearly noticed succinct low-level sounds when the going got tough, that I have never heard before anywhere. I came home worried, and sure enough, the sounds are there but indistinct, inarticulate. However, they are clearly audible - both CD and LP - through the cheap Grado headphones on the Revox, which go through a tape loop in the preamp, then Hero interconnects to the Revox, and through more electronics and a volume control in there... so the sources are not the problem, and the preamp isn't either. And considering that the interconnects are the same from the DAC/phono to the preamp and then to the amps, they are not the problem either. That leaves the 400s, possibly the speaker cables, and perhaps the electrostatic panels and their crossover. I strongly suspect it's the 400s, which raises the anticipation to get those 500s in here... this is going to be a lot of fun.

Meantime, I begin to wonder, where does this really end? And what a great thing to know that there is so much incredible information in those grooves and digital pits... captured decades ago. What have we been doing wrong on the reproductive side?

Thanks micro - this begs another WTH.

Meantime, this balanced-in module in the preamp has proven to be a god-send for my digital. It amplifies the signal from the DAC so well, adding quite a bit of bottom end oomph and control that was really missing before. At the same time, it's amplifying distortions, and primarily IMD. It is simply fascinating to play with the digital volume control on the DAC and notice how dramatically the sound can change. And when I thought that lowering the volume would always improve things, I am finding out that certain midrange notes are then ringing, depending on the volume level. So the hunt for a perfect setting has become an obsession. Whereas I was running it at 53.5 (ringing) to 54.0 (noticeable IMD) before, I have now settled on 53.0 and things are so smooth, and believe it or not, a tiny bit more dynamic. It's simply fascinating to witness the change in character, and all the more reason I hate digital volume controls - they really show their ugly face in a high resolution system. Ugh!

IMD is such an incredibly nasty distortion, and hard to train your ear on it. But it's quite apparent with large-scale choral music, where the chorus can sound really distorted. I was able to hone in on that on my analog side, and drop the arm quite a bit while also re-setting all other parameters. Then, using that as a reference while playing RR LPs, I was able to adjust the DAC's volume control with the equivalent HDCD versions, to the point that an A/B between them with the same material renders a virtually identical picture, which is a great place to be.

But what a freaking ride it has been.