The Headcase Stax thread

[kevin gilmore]

I was referring to audio transformers in the audio path. And i'm sure you know this. I have tested a number of lundahl input transformers, and besides being very sensitive to even the slightest amounts of dc, they have 2nd harmonic greater than the .05% you state, just by themselves. I like transformers in power supplies, and rf isolation. At work, lots and lots of 400mhz,500mhz, 600mhz and 5,10 and 35 ghz where striplines turn into transformers real easily without any ferrite.

Take a look at that picture again, the hanging electrolytic and flying resistor at the left side. Is this the kind of quality that MSB produces, if I was a customer and bought something in this price range that looked like that I would be mighty pissed.  OH wait someone did it for me and sent me a MSB platinum dac. with lots of hidden cuts and jumps and hanging parts on the bottom sides of the dac modules. I posted the pictures, but i'm too lazy to look for them.

At this price range the audio jewelry has to be absolutely perfect inside and out. D'Agostino power amps pass the test, Boulder, not so much. Krell has fallen very far in the last few years. Whats going to happen to levinson and revel now that Samsung owns them is going to be really horrible.

I'm clearly not the target customer for msb products, I absolutely have the money to write a check for the pair, but would never do so. Even if I had 100 times as much money as I do now, I would still not buy the msb pair. Nor would I buy the sennheiser Orpheus 2, or the hifiman.

On the other hand a 2019 Z06,ZR1, or C8 as my retirement vehicle (complete with tennis balls) is a done deal.

Back to numbers, 440 VRMS.  is that stator to stator, or stator to ground.  seems like stator to stator to me. So 600v peak to peak stator to ground. maybe that is why you don't want it clipping? A number of people I know listen at more than 440 VRMS. Even though they should not. These are the same people who hate srm323 because they clip so easily.

 

 

Edited November 26, 2016 by kevin gilmore

[JimL]

On November 24, 2016 at 0:19 PM, Dusty Chalk said:

 

17 hours ago, DJS said:

The frequency spec should read 5Hz-20Khz +-0.8dB driving one Stax SR-009 at 100Vrms. This is mostly due to the amps 6500 Ohm output impedance driving the low Q capacitor of the headphones.

Um, hang on.  The SR-009 is specified as 110 pf capacitative load.  With an output impedance of 6500 ohms, the high frequency -3 dB roll-off should be around 222 kHz, and -0.8 dB should be around 100 kHz, not 20 kHz.  

[kevin gilmore]

its a numbers game.  the output of the amplifier is balanced, so is it 6500 ohms per output, or 6500 ohms total

if its 6500 ohms per output then the rolloff just due to the resistance and the load makes it -3db at 103khz which is -.167db at 20khz

so the amplifier would be rolling off faster than that.

all of my amplifiers have 5.1k output resistors on each stator driver. and before those resistors the amps have a much wider frequency range than that.

AND is that 6500 ohms include the required 5.1k safety resistors to prevent the headphones from sudden death, or is that the real output impedance of the amplifier. Because if its the later, its as bad as another product we know of around here

Edited November 26, 2016 by kevin gilmore

[JimL]

Either way I'm thinking that the input transformer could be contributing to the HF roll-off as well to get -0.8 dB at 20 kHz.  I'm just not clear on the benefits of an input transformer in the first place, unless it's to filter out HF crap from the DAC (NB, totally uninformed wild ass speculation).

Edited November 26, 2016 by JimL

[kevin gilmore]

a transformer doing that?  completely unheard of 

but an amp without any feedback of any kind is going to contribute to this. Even at 15 watts per stator driver

 

[mypasswordis]

I was going to write a long response, but it boils down to this: we need pics of the underside where you claim most of the semiconductors are, along with the heat pipes. All I see in the power supply are diodes, electrolytic caps, zener diode strings, bleeder resistors, and whatever those things are in between the caps. Also, since you are eager to share your measurements, you should be willing to send your amp to an independent third party for measurement verification. Some of these numbers seem on the iffy side, especially given what we can see. You certainly don't like excessive costs, as all the components are the cheapest you can find on Mouser. Even those trimpots don't look like real Bourns. If they are, I stand corrected. If your heatsink is dissipating 60W (it doesn't look like the one on the other side is connected to anything because only the main power transformer, low voltage supply, and empty module slot is there) why put the HV caps right next to them and then wedge your wiring right in between?

[kevin gilmore]

I can't find the power supply pics, but here are some of them.  sloppy evidently going all the way back to 2007, looks like djs designed much of this too. definitely like the hand drilled hole on the preamp boards.

 

Edited November 26, 2016 by kevin gilmore

[DJS]

3 hours ago, kevin gilmore said:

I can't find the power supply pics, but here are some of them.  sloppy evidently going all the way back to 2007, looks like djs designed much of this too. definitely like the hand drilled hole on the preamp boards.

 

Yes you have me on the ropes... everything shown are customer requested retrofits, not part of the original design of that DAC model.... A USB input and latter model volume modules added to a previous generation DAC as a retrofit, the dac shown has at least three generations of modules in it indicating a long upgrade process for that customer... That particular DAC shown even needed a retrofit to the motherboard power bus (wires in lower left corner and to the left of the blue board) to support the excess power required for the late model DSP (blue board). So lets see its a 2007 motherboard with 2008 volume module in it, 2009 DSP module  and about a 2011-12 model USB input. Most companies would tell the customer "sorry you can't stick this new hot input or that newer model volume control in your old outdated model, buy this years model instead." We have always tried to make customers happy by retrofiting old product if it was possible.  In fact the previous owner made it company policy, if we could upgrade a product then we would upgrade it no matter how difficult or hacked the upgrades were. I used to strongly disagree with him about these messy "hacked" upgrades but after he forced me to talk with our customers directly about what they wanted I did learn an important lesson. Yes one offs and retrofits require hand work and "mess" but they make customers happy (as long as they work well, which with some of the mandated "upgrades" wasn't always the case and definitely results in angy customers) because they get what they want without having to re-buy a product every time the fast moving technology changes. I have learned the lesson that customers want a long life span out of their products so well that at this point that all of our lattest products contain obscenely flexible hardware to keep all the hand retrofits to a minimum wherever the technoloy wind may blow. For example the lattest DAC modules are built of software defined analog blocks so that they can be configured on the fly as multibit, multibit delta-sigma (8-2bit) or single bit delta-sigma and support sample rates from 44.1khz to 98Mhz. Another example is an input module design that supports any digital format up to 300Mbps (for example 12 channels of 32 bit/768Khz pcm) with an electrical and thermal design to 12W per module to support most any interface from simple s/pdif to the latest full blown multichannel network computer endpoint. All of this is probably overkill but may tun out to be necessary 5 years from now. I will also say that all of my designs have also much improved with time. My first product design was the MSB Link DAC and even tho most customers loved it I now view that design as naive, overly complex, underperforming and formulaic. When I had the chance to redo that design years latter I did it on a busness card sized PCB with a total build cost of $4 and we gave it away as "swag" at a couple of trade shows. The recipients may not have realized it at the time but that silly "buisness card" DAC was much superior to the Link DACs they may have already owned. However my lattest designs, for example the Select DAC, I find satisfingly divergent and polished with circuit design maximally refined, simplified and unique.

And now I'm tired and feeling antisocial after such flames so I won't be continuing this argument. I respond much better to direct questions rather than sarcastic inuendo like that above. I thought that maybe there was some open minded people out there that might be curious to know what is really going on with a product that none of them will ever be able to afford (myself included, I only get to have temporary loan of prototypes for testing). It seems if I design something that breaks established convention (with specs, design whatever) established designers feel that I stepped on their toes or invaded their private domain and require a "whipping." I learned my lesson this time, I don't think I will ever try post any useful information again, I will just let the flames roar in the vacuum.

[kevin gilmore]

I almost forgot the most important bit.

djs welcome to headcase!

where the woman are strong, all the men are good-looking and the children are above average

were you going to say something or just repost my pictures?

edit: needed to get the quote correct

Edited November 26, 2016 by kevin gilmore

[astrostar59]

23 hours ago, Bjorn said:

That's some funny ass shit coming from the guy who uses a tube dac to make his 009 sound right. 

Oh my, tubes sound so bad they are used in the T2 and BHSE. Not accurate at all then?

[kevin gilmore]

so what function do tubes do in a dac?

unless you plan on building a modern version of an eniac, the answer has to be the output buffer. Everything up to that buffer has to be solid state. So you get your choice of a tube cathode follower, or a tube driving an output transformer. The cathode follower is going to have a fairly high output impedance, something like 10k ohms so it might have trouble driving some cables, and the transformer output will have a low output impedance, and a bit more second harmonic distortion.

your other choice is a solid state buffer of some kind.

all 3 are going to sound different, some people are going to definitely like one over the other.

the solid state buffer is likely to have less thd and more ability to drive long cables.

if you have a solid state dac, and want some tube goodness add one of these

http://schiit.com/products/saga

Edited November 26, 2016 by kevin gilmore

[mypasswordis]

2 hours ago, DJS said:

I will also say that all of my designs have also much improved with time. My first product design was the MSB Link DAC and even tho most customers loved it I now view that design as naive, overly complex, underperforming and formulaic. When I had the chance to redo that design years latter I did it on a busness card sized PCB with a total build cost of $4 and we gave it away as "swag" at a couple of trade shows. The recipients may not have realized it at the time but that silly "buisness card" DAC was much superior to the Link DACs they may have already owned. However my lattest designs, for example the Select DAC, I find satisfingly divergent and polished with circuit design maximally refined, simplified and unique.

And now I'm tired and feeling antisocial after such flames so I won't be continuing this argument. I respond much better to direct questions rather than sarcastic inuendo like that above. I thought that maybe there was some open minded people out there that might be curious to know what is really going on with a product that none of them will ever be able to afford (myself included, I only get to have temporary loan of prototypes for testing). It seems if I design something that breaks established convention (with specs, design whatever) established designers feel that I stepped on their toes or invaded their private domain and require a "whipping." I learned my lesson this time, I don't think I will ever try post any useful information again, I will just let the flames roar in the vacuum.

 

You don't know the people here if you think a large number of us can't afford stuff like MSB. We simply choose not to because your amp looks, at first glance, to be a somewhat questionably built $300 box of parts (not including the casing or main power transformer), for $37k. If you truly wanted to share with us "what is really going on" you would have posted pics of the underside of the PCB instead of ranting and telling everyone you're not going to post anymore about enlightening us. Given that you yourself have mentioned you have built something that was better than what you sold people, for $4, there seems to be a trend. Some of us used stronger rhetoric than others, but we gave you a chance to tell us what was really going on and verify your measurements from an independent party, and you decided to run instead.

Best of luck in your future endeavors.

[JimL]

5 hours ago, kevin gilmore said:

A number of people I know listen at more than 440 VRMS. Even though they should not. These are the same people who hate srm323 because they clip so easily.

 

 

WOW!  That's 113 dB SPL.  Definitely won't like my SRX Plus either.  It'll be a clipping machine at those levels.  As someone said, "That ringing in your ears is the scream of a dying nerve cell."

[astrostar59]

8 hours ago, kevin gilmore said:

so what function do tubes do in a dac?

unless you plan on building a modern version of an eniac, the answer has to be the output buffer. Everything up to that buffer has to be solid state. So you get your choice of a tube cathode follower, or a tube driving an output transformer. The cathode follower is going to have a fairly high output impedance, something like 10k ohms so it might have trouble driving some cables, and the transformer output will have a low output impedance, and a bit more second harmonic distortion.

your other choice is a solid state buffer of some kind.

all 3 are going to sound different, some people are going to definitely like one over the other.

the solid state buffer is likely to have less thd and more ability to drive long cables.

if you have a solid state dac, and want some tube goodness add one of these

http://schiit.com/products/saga

Hi Kevin

I don't know all the technicalities. But looking at a good tubed pre-amplifier design, a tube regulated power supply and tube line stage can sound very good I found. Some very nice pre-amps with this topology. I may be wrong, but I am thinking a DAC is basically a pre-amp with a digital board (hugely simplified analogy). Lampizator use tubed regulated PS and output for example. The Golden Gate sounds very good. I am not saying tubed DACs are better, only can sound great as does solid state.

[Voltron]

Oh brother.

[sorenb]

[astrostar59]

2 hours ago, sorenb said:

You heard the Lampizator Golden Gate? Thought not. Come on this forum is supposed to avoid the review without hearing thing that HF gets accused of 100% of the time. I see folk over there who comment on gear they actually own, same on here. But I ignore ones that say stuff and haven't heard it.

Ok MSB amp is a freak as the price is insane, so up for flack. 

Edited November 27, 2016 by astrostar59

[wink]

Astro, perhaps, if you took the time to know somewhat of the topic you were posting about, and before you took it upon yourself to sarcastically call out those far more knowledgeable posters contributing in the various threads in this forum, you may not be the continual equivalent of soylent green and comic relief that seems to be your undeniable forte whilst you attempt to add to the tenor of this forum and this thread in particular, but sadly, it is my melancholy duty to inform you that your postings are comical at best, and asinine in general thus resulting in the many negatory replies to your posts, and, adding to the status quo, your total inability to, or perhaps complete disregard for the rebuttals your posts receive, you continue to chronically suffer from the proverbial foot-in-mouth disease, and contrary to popular belief, this post is not a diatribe against you but a rather belated attempt by myself to attempt, perhaps, not futilely, to educate and admonish you with the intention of rescuing you from further displays by yourself of your penchant to display your ignorance of the subject matter and it's context which is so necessary to the understanding of the postings herein contained, plus it also has the added benefit of ameliorating the comical content of the ever present contrarians who just love to point out your fallacious understandings which are so frequently proffered in your posts for their amusement and delectation but to the detraction of your personal prestige within these hallowed portals of knowledge and dissemination thereof, which has contributed massively to those here with the right attitude and resulting in their elevation of worth, knowledge and skills in DIY as well as other areas of social interaction as can be readily seen and recognized within this forum, and so I hope that this slight rebuke is taken in it's proper context as an educational expose which will no doubt be seen as negatively impacting on the fun factor by those who are awaiting every post of yours to ascertain what mileage may be derived from your ignorance which is overtly expressed in you posts and to be butt of ridicule and demeaning jesting from the more astute and enlightened denizens with a greater than modicum of humour and irony.

[Torpedo]

It was Martin L. King Jr who said "Nothing in all the world is more dangerous than sincere ignorance and conscientious stupidity". Now Astrowhatever, you're beyond dangerous and becoming nauseating.

[astrostar59]

3 minutes ago, wink said:

Astro, perhaps, if you took the time to know somewhat of the topic you were posting about, and before you took it upon yourself to sarcastically call out those far more knowledgeable posters contributing in the various threads in this forum, you may not be the continual equivalent of soylent green and comic relief that seems to be your undeniable forte whilst you attempt to add to the tenor of this forum and this thread in particular, but sadly, it is my melancholy duty to inform you that your postings are comical at best, and asinine in general thus resulting in the many negatory replies to your posts, and, adding to the status quo, your total inability to, or perhaps complete disregard for the rebuttals your posts receive, you continue to chronically suffer from the proverbial foot-in-mouth disease, and contrary to popular belief, this post is not a diatribe against you but a rather belated attempt by myself to attempt, perhaps, not futilely, to educate and admonish you with the intention of rescuing you from further displays by yourself of your penchant to display your ignorance of the subject matter and it's context which is so necessary to the understanding of the postings herein contained, plus it also has the added benefit of ameliorating the comical content of the ever present contrarians who just love to point out your fallacious understandings which are so frequently proffered in your posts for their amusement and delectation but to the detraction of your personal prestige within these hallowed portals of knowledge and dissemination thereof, which has contributed massively to those here with the right attitude and resulting in their elevation of worth, knowledge and skills in DIY as well as other areas of social interaction as can be readily seen and recognized within this forum, and so I hope that this slight rebuke is taken in it's proper context as an educational expose which will no doubt be seen as negatively impacting on the fun factor by those who are awaiting every post of yours to ascertain what mileage may be derived from your ignorance which is overtly expressed in you posts and to be butt of ridicule and demeaning jesting from the more astute and enlightened denizens with a greater than modicum of humour and irony.

Wow, a lot of time to write that. Impressed. Hmm, I post about stuff I have either owned, or heard. I don't say anything is garbage unless I hear it first. I understand there are others more knowledgable in technical matters who can do that. Respect. But I post as an audiophile who likes decent sounding gear. Simple. I don't join in the bully club. Now if you enjoy that sort of thing, maybe you need help.

[sorenb]

 

[kevin gilmore]

10 hours ago, JimL said:

WOW!  That's 113 dB SPL.  Definitely won't like my SRX Plus either.  It'll be a clipping machine at those levels.  As someone said, "That ringing in your ears is the scream of a dying nerve cell."

pabbi1 at canjam2010 drove my T2 into clipping. you could hear it across the room. He was very happy. Everyone else was scared

there were others that stopped by my office and roughly the same thing.

[swt61]

Why are you still here Astrolube69? No one agrees with anything you say, your opinions are ridiculous, you're constantly berated, you have no fashion sense (OK I guessed on that one), and you're just generally not welcome here...

So what keeps you coming back?

Oh, wait. I've known guys like you...

[Bjorn]

2 hours ago, wink said:

Astro, perhaps, if you took the time to know somewhat of the topic you were posting about, and before you took it upon yourself to sarcastically call out those far more knowledgeable posters contributing in the various threads in this forum, you may not be the continual equivalent of soylent green and comic relief that seems to be your undeniable forte whilst you attempt to add to the tenor of this forum and this thread in particular, but sadly, it is my melancholy duty to inform you that your postings are comical at best, and asinine in general thus resulting in the many negatory replies to your posts, and, adding to the status quo, your total inability to, or perhaps complete disregard for the rebuttals your posts receive, you continue to chronically suffer from the proverbial foot-in-mouth disease, and contrary to popular belief, this post is not a diatribe against you but a rather belated attempt by myself to attempt, perhaps, not futilely, to educate and admonish you with the intention of rescuing you from further displays by yourself of your penchant to display your ignorance of the subject matter and it's context which is so necessary to the understanding of the postings herein contained, plus it also has the added benefit of ameliorating the comical content of the ever present contrarians who just love to point out your fallacious understandings which are so frequently proffered in your posts for their amusement and delectation but to the detraction of your personal prestige within these hallowed portals of knowledge and dissemination thereof, which has contributed massively to those here with the right attitude and resulting in their elevation of worth, knowledge and skills in DIY as well as other areas of social interaction as can be readily seen and recognized within this forum, and so I hope that this slight rebuke is taken in it's proper context as an educational expose which will no doubt be seen as negatively impacting on the fun factor by those who are awaiting every post of yours to ascertain what mileage may be derived from your ignorance which is overtly expressed in you posts and to be butt of ridicule and demeaning jesting from the more astute and enlightened denizens with a greater than modicum of humour and irony.

I have to admit I fell asleep reading that, but the amount of commitment on display here definitely deserves a LIKE 

[nopants]

i imagine astroturf endures being berated because people still give him information that he can regurgitate over at headfi, even if he doesn't understand it. it lines up if you consider how he's also reviving dead threads.

or maybe it's just some weird martyr complex, either way the discussion takes a nosedive pretty consistently