[Jaytor]

I replaced my Terminator II with a Lampizator Golden Atlantic TRP. The T2 is ultra-precise and an exceptional DAC, but the Lampizator is more dynamic, has a bigger soundstage, and it's more musical. The T2 is the professional pianist who reads music, and the Lampi is the jazz musician who plays from the heart. If you prefer the sound of tube amps/preamps over solid-state, you'll get more of what you like with a decent tube DAC. 

I think if I was going to replace my Terminator Plus (and not build something myself), it would probably be a Lampizator DAC. I've really enjoyed the ones I've heard. The Lampizator Poseidon DAC I heard in the Songer room at CAF sounded sublime.

[jmimac351]

I just like hearing what people have and like.

I've owned a lot of tube stuff (still tube) and how found certain solid state that gets me the musicality I like from tubes, along with the bass impact / ease of use / lack of noise. 

Tubes
Around 20 years ago I heard Joule Electra VZN OTL amps at the CES show with Merlin VSM speakers. I already owned the Merlin VSMs, and they were picky about gear... an aside... the reason WHY they are picky about gear is know to me now, and Danny is getting ready to fix it.  So, the Joule VZN amps are just magic.  OTL... the tube is connected to the driver.  The midrange bloom is incredible.  There was another feature... dialing in the amount of feedback.  The magic happened with overall feedback was dial as low as possible.  The other features of the amp is that is would heat a gymnasium, and starting it up as like firing up a steam driven locomotive... coal fired furnace and all.  It doesn't have a "power switch", but a Variac... you turn a big dial to start applying current to the tubes and what the levels come up on the meter.  It is an "enthusiast" thing... but again... MAGIC.

Here is my Joule Electra VZN-80 OTL amp with the hood off...



For front end I have (not in use) Joule LAP 150 preamp.  Dual box unit, point to point wired... all tubes.

Joule Electra LAP150



I have also played with some hybrid stuff, including an (unobtainable) Joule Electra VAMP integrated.  Tube front end, Mosfet output.  Point to point wired. Very little overall feedback... Damping Factor 13. Sounds so sweet!

Joule Electra VAMP









Along the way, I'd played with various solid state stuff, CODA, Marantz, Krell... some other tube gear.  Nothing remarkable about the solid state stuff (yet), and just because something had tubes in it was no guarantee it sounded good. Not like my Joule Electra stuff.

So... as my willingness and ability to put more money into stuff I wanted, I really started looking at "why" certain things I liked sounded better.  And one thing I have hit on that has lead me to buy a particular set of gear is this:

Zero Global Negative Feedback

Year before last, I took a flyer on buying an Ayre Acoustics VX-5 Twenty amp.  I had been reading a lot of the thoughts of Charlie Hansen, founder of Ayre.  Charlie was a "tube guy", but he didn't like the hassle of tubes.  His quest was to get the reliability of solid state and the magic of tubes.  He started hitting on 2 things, and it's fundamental to Ayre gear: 

• Zero Negative Feedback
• Fully Differentially Balanced

He became convinced that he'd just about gotten "there"...i.e., solid state reliability / ease of use with the musicality of tubes.  Charlie was a very opinionated guy (he passed years ago from complications from a cycling accident).  He couldn't explain exactly "Why" he thought the secret was in Zero Negative Feedback, but he thought it may have had to do with "Time Alignment" of the signal.  "Timing being smeared".  Now, where else have we heard commentary about "Timing and Smearing"?  I believe Danny has hit on this?

So, finding that the Ayre VX-5 Twenty sounded "right" and "musical" to me, I then acquired an Ayre KX-5 Twenty preamp.  Then an Ayre QB-9 Twenty DAC.  Things got better and better.  The KX-5 Twenty preamp is AWESOME.  Everything I run is via balanced connections.

So, my current, preferred setup is this:

• Ayre QB-9 Twenty DAC
• Ayre KX-5 Twenty Preamp
• Ayre VX-5 Twenty Amp

I ABSOLUTELY LOVE IT.  The retail pricing on this stuff is up there... but I buy stuff "used and right". Remember, what something actually costs you is the difference between what you buy it for and what you sell it for.  This financial strategy is fully "Audiophile Approved".  (Plus, it's true - notwithstanding the opportunity costs of earning on the money).  But this stuff adds enjoying to my life every day... put a number on that.

In fact, I've picked up some other Ayre gear that is "secret stuff"... "secret, really good stuff that doesn't cost a fortune". 

1) AX-7e Integrated.  It can be an integrated, but also has a "Pass Thru" function, so it can "just be an amp".  Plus, with the way it's designed, the volume "wakes up" to make an adjustment, then "goes back to sleep".  And, any inputs not being used are "put to sleep".  So, it's SUPER quiet... as is all Ayre gear.  $1,250 used.  60w/Ch 8ohms / 120wCh 4ohms.  And... it "punches above its weight".

2) K5xe MP preamp.  This is less than half price (used) of my KX-5 Twenty preamp.  But is REALLY good.  It is reference quality... ~$2100 used. This is a "classic" piece.

So, that's what I use and why I use it.  The thing is, "Zero Negative Feedback" in solid state stuff is not common.  I also happen to think that it's a big reason why a lot of other solid state gear sounds "pretty much the same".  I wanted something different and designed differently, for a reason.

A thing about lack of negative feedback... it may not measure as well / it's harder to get it to measure well.  So, if something doesn't measure as well when there isn't as much feedback being employed, why do it?  Why even bother with it?  Why argue with people are are convinced that "measurements are the only thing that matter and if you think otherwise, you are just kidding yourself".  In other words, why argue with the crowd at ASR (I don't bother).

Well, the reason is, many people think gear with less global negative feedback SOUNDS BETTER. And I completely agree with that. 

And here's the thing... even if it "doesn't sound better"... it doesn't matter.  I think it DOES sound better... it is a visceral reaction.  When something I hear is "right"... I just "know it's right".  When something is missing... I quickly get bored with it... something is missing... this is boring me. 

Some will say, but the measurements!  You're just mentally kidding yourself!  To that I would ask:

How do you know you're measuring the right thing?  In fact, I think the full commitment to "measurement above all else" is actually not "the intellectual approach" to this (although certainly could be the arrogant approach).  I think it is the less enlightened approach because it ignores the fact that of "the unknown unknowns..."  How do you know you know everything about what is being measured, what is / isn't being account for?  They don't.

Another issue with a lot of Feedback / High Damping factor... I have found it can sap the "magic" from the presentation. Some may think, "but isn't it a great idea to control the drivers with a lot of dampening factor?"  Well, why isn't "Servo Control amp" an idea being pushed for Midrange / Tweeter drivers?  I would suggest it's because it's not needed... I want the midrange to bloom.  Yet, it can be argued to use it to control the higher moving mass of a heavier woofer cone.  So, higher feedback / higher damping factor... can lead to a "thinner sound"... less feedback / lower damping factor... more "bloom", more "magic"... more like "tubes".

But here's another thing... I am not closed minded about my current approach.  The guy who bought my Magnepan 3.7i INSISTED that I listen to a DAC he brought me when he picked up the speakers.  He left it with me.  It was a Gustard X16.  Well, it was soft and lifeless... and when I looked it up on the ASR "Master List", it ranked as one of their top DACs.  Go Figure. Measurements aren't everything, for me.

Another thing I am playing with... it's a piece of "studio" gear - RME ADI-2 DAC FS.  REALLY COOL!  It's a DAC, it's a Preamp, it's a 5 band PEQ.  It's a ton of fun to play with and so versatile. I've got it in and out of "The Big Rig".  I don't see it going anywhere because it's just so flexible (and I like how it sounds too).  The one I have is a "pre fire" unit with AKM4493 DAC chip.

Another example of being "open to new things"... and something I am very interested in trying.  Something that you may even like to try with your NX-Otica, given the sensitivity.  Have a look at the upcoming Schiit Audio Aegir 2.  Why?  Well... Jason Stoddard is playing with the "controversial" topic of less negative feedback.  The new Aegir 2 will have a Damping Factor of 10!.  Output Impedance of .8ohm!  (Damping Factor = 8ohm / Output Impedance) Find another solid state amp with that kind of low damping factor... for $899!  As soon as it's available, I am ordering one.  I want to try it... see if I like it... learn a bit more about "the path" I'm on.  Here's my hunch about the Aegir 2... I think it is going to be crazy good.  It will be 25w/ch into 8ohm, 50w/ch into 4ohm. They can be run as a pair of mono at 100w/ch. It just seams like a potentially very high sound quality option for the higher sensitivity NX speakers, for (relatively) very little money.

Another interesting thing about the topic of Negative Feedback / Schiit / Jason Stoddard.  I shared quite a bit about this "zero negative feedback thing" on his forum thread... and he became VERY annoyed with me... saying that "it wasn't the one truth"... and then a few weeks later announced an amp in Aegir 2 that had the qualities I was touting!!!  HA!  In the description of the amp / negative feedback, he refers to it as "controversial" - which I found very odd.  But I think I understand why he said that... it's because he has to "play the measurement game" and straddle the fence with the pitchfork measurement crowd over at ASR.  But why would Jason Stoddard take this potential criticism on?  Why deal with that potential hassle with the original Aegir is already said to sound pretty good.  Well, he said it himself regarding Aegir 2 and it's key "Halo Feedback" feature:

"It sounds better." (Evidently something sounding better is "Controversial").  Imagine having to placate this stuff when trying to design gear that sounds better? 

So, those are my brief thoughts on this matter.  Hopefully it helps.

[BrandonB]

I've owned a lot of tube stuff (still tube) and how found certain solid state that gets me the musicality I like from tubes, along with the bass impact / ease of use / lack of noise. 

Tubes
Around 20 years ago I heard Joule Electra VZN OTL amps at the CES show with Merlin VSM speakers. I already owned the Merlin VSMs, and they were picky about gear... an aside... the reason WHY they are picky about gear is know to me now, and Danny is getting ready to fix it.  So, the Joule VZN amps are just magic.  OTL... the tube is connected to the driver.  The midrange bloom is incredible.  There was another feature... dialing in the amount of feedback.  The magic happened with overall feedback was dial as low as possible.  The other features of the amp is that is would heat a gymnasium, and starting it up as like firing up a steam driven locomotive... coal fired furnace and all.  It doesn't have a "power switch", but a Variac... you turn a big dial to start applying current to the tubes and what the levels come up on the meter.  It is an "enthusiast" thing... but again... MAGIC.

Here is my Joule Electra VZN-80 OTL amp with the hood off...



For front end I have (not in use) Joule LAP 150 preamp.  Dual box unit, point to point wired... all tubes.

Joule Electra LAP150



I have also played with some hybrid stuff, including an (unobtainable) Joule Electra VAMP integrated.  Tube front end, Mosfet output.  Point to point wired. Very little overall feedback... Damping Factor 13. Sounds so sweet!

Joule Electra VAMP









Along the way, I'd played with various solid state stuff, CODA, Marantz, Krell... some other tube gear.  Nothing remarkable about the solid state stuff (yet), and just because something had tubes in it was no guarantee it sounded good. Not like my Joule Electra stuff.

So... as my willingness and ability to put more money into stuff I wanted, I really started looking at "why" certain things I liked sounded better.  And one thing I have hit on that has lead me to buy a particular set of gear is this:

Zero Global Negative Feedback

Year before last, I took a flyer on buying an Ayre Acoustics VX-5 Twenty amp.  I had been reading a lot of the thoughts of Charlie Hansen, founder of Ayre.  Charlie was a "tube guy", but he didn't like the hassle of tubes.  His quest was to get the reliability of solid state and the magic of tubes.  He started hitting on 2 things, and it's fundamental to Ayre gear: 

• Zero Negative Feedback
• Fully Differentially Balanced

He became convinced that he'd just about gotten "there"...i.e., solid state reliability / ease of use with the musicality of tubes.  Charlie was a very opinionated guy (he passed years ago from complications from a cycling accident).  He couldn't explain exactly "Why" he thought the secret was in Zero Negative Feedback, but he thought it may have had to do with "Time Alignment" of the signal.  "Timing being smeared".  Now, where else have we heard commentary about "Timing and Smearing"?  I believe Danny has hit on this?

So, finding that the Ayre VX-5 Twenty sounded "right" and "musical" to me, I then acquired an Ayre KX-5 Twenty preamp.  Then an Ayre QB-9 Twenty DAC.  Things got better and better.  The KX-5 Twenty preamp is AWESOME.  Everything I run is via balanced connections.

So, my current, preferred setup is this:

• Ayre QB-9 Twenty DAC
• Ayre KX-5 Twenty Preamp
• Ayre VX-5 Twenty Amp

I ABSOLUTELY LOVE IT.  The retail pricing on this stuff is up there... but I buy stuff "used and right". Remember, what something actually costs you is the difference between what you buy it for and what you sell it for.  This financial strategy is fully "Audiophile Approved".  (Plus, it's true - notwithstanding the opportunity costs of earning on the money).  But this stuff adds enjoying to my life every day... put a number on that.

In fact, I've picked up some other Ayre gear that is "secret stuff"... "secret, really good stuff that doesn't cost a fortune". 

1) AX-7e Integrated.  It can be an integrated, but also has a "Pass Thru" function, so it can "just be an amp".  Plus, with the way it's designed, the volume "wakes up" to make an adjustment, then "goes back to sleep".  And, any inputs not being used are "put to sleep".  So, it's SUPER quiet... as is all Ayre gear.  $1,250 used.  60w/Ch 8ohms / 120wCh 4ohms.  And... it "punches above its weight".

2) K5xe MP preamp.  This is less than half price (used) of my KX-5 Twenty preamp.  But is REALLY good.  It is reference quality... ~$2100 used. This is a "classic" piece.

So, that's what I use and why I use it.  The thing is, "Zero Negative Feedback" in solid state stuff is not common.  I also happen to think that it's a big reason why a lot of other solid state gear sounds "pretty much the same".  I wanted something different and designed differently, for a reason.

A thing about lack of negative feedback... it may not measure as well / it's harder to get it to measure well.  So, if something doesn't measure as well when there isn't as much feedback being employed, why do it?  Why even bother with it?  Why argue with people are are convinced that "measurements are the only thing that matter and if you think otherwise, you are just kidding yourself".  In other words, why argue with the crowd at ASR (I don't bother).

Well, the reason is, many people think gear with less global negative feedback SOUNDS BETTER. And I completely agree with that. 

And here's the thing... even if it "doesn't sound better"... it doesn't matter.  I think it DOES sound better... it is a visceral reaction.  When something I hear is "right"... I just "know it's right".  When something is missing... I quickly get bored with it... something is missing... this is boring me. 

Some will say, but the measurements!  You're just mentally kidding yourself!  To that I would ask:

How do you know you're measuring the right thing?  In fact, I think the full commitment to "measurement above all else" is actually not "the intellectual approach" to this (although certainly could be the arrogant approach).  I think it is the less enlightened approach because it ignores the fact that of "the unknown unknowns..."  How do you know you know everything about what is being measured, what is / isn't being account for?  They don't.

Another issue with a lot of Feedback / High Damping factor... I have found it can sap the "magic" from the presentation. Some may think, "but isn't it a great idea to control the drivers with a lot of dampening factor?"  Well, why isn't "Servo Control amp" an idea being pushed for Midrange / Tweeter drivers?  I would suggest it's because it's not needed... I want the midrange to bloom.  Yet, it can be argued to use it to control the higher moving mass of a heavier woofer cone.  So, higher feedback / higher damping factor... can lead to a "thinner sound"... less feedback / lower damping factor... more "bloom", more "magic"... more like "tubes".

But here's another thing... I am not closed minded about my current approach.  The guy who bought my Magnepan 3.7i INSISTED that I listen to a DAC he brought me when he picked up the speakers.  He left it with me.  It was a Gustard X16.  Well, it was soft and lifeless... and when I looked it up on the ASR "Master List", it ranked as one of their top DACs.  Go Figure. Measurements aren't everything, for me.

Another thing I am playing with... it's a piece of "studio" gear - RME ADI-2 DAC FS.  REALLY COOL!  It's a DAC, it's a Preamp, it's a 5 band PEQ.  It's a ton of fun to play with and so versatile. I've got it in and out of "The Big Rig".  I don't see it going anywhere because it's just so flexible (and I like how it sounds too).  The one I have is a "pre fire" unit with AKM4493 DAC chip.

Another example of being "open to new things"... and something I am very interested in trying.  Something that you may even like to try with your NX-Otica, given the sensitivity.  Have a look at the upcoming Schiit Audio Aegir 2.  Why?  Well... Jason Stoddard is playing with the "controversial" topic of less negative feedback.  The new Aegir 2 will have a Damping Factor of 10!.  Output Impedance of .8ohm!  (Damping Factor = 8ohm / Output Impedance) Find another solid state amp with that kind of low damping factor... for $899!  As soon as it's available, I am ordering one.  I want to try it... see if I like it... learn a bit more about "the path" I'm on.  Here's my hunch about the Aegir 2... I think it is going to be crazy good.  It will be 25w/ch into 8ohm, 50w/ch into 4ohm. They can be run as a pair of mono at 100w/ch. It just seams like a potentially very high sound quality option for the higher sensitivity NX speakers, for (relatively) very little money.

Another interesting thing about the topic of Negative Feedback / Schiit / Jason Stoddard.  I shared quite a bit about this "zero negative feedback thing" on his forum thread... and he became VERY annoyed with me... saying that "it wasn't the one truth"... and then a few weeks later announced an amp in Aegir 2 that had the qualities I was touting!!!  HA!  In the description of the amp / negative feedback, he refers to it as "controversial" - which I found very odd.  But I think I understand why he said that... it's because he has to "play the measurement game" and straddle the fence with the pitchfork measurement crowd over at ASR.  But why would Jason Stoddard take this potential criticism on?  Why deal with that potential hassle with the original Aegir is already said to sound pretty good.  Well, he said it himself regarding Aegir 2 and it's key "Halo Feedback" feature:

"It sounds better." (Evidently something sounding better is "Controversial").  Imagine having to placate this stuff when trying to design gear that sounds better? 

So, those are my brief thoughts on this matter.  Hopefully it helps.

I had to read this a few times to absorb.  This is very interesting and something to think about. Reading the specs of an amplifier you would look at damping factor to determine negative feedback? 

[Glady86]

In my limited experiences, tube gear gives a more live or you’re there experience. Don’t know why, is it the extra distortion measurement geeks complain about. 

Note: This statement was from a certified “audiophool”

[jmimac351]

I had to read this a few times to absorb.  This is very interesting and something to think about. Reading the specs of an amplifier you would look at damping factor to determine negative feedback?

That's what I've found. Yes.  Damping Factor can be determined by looking at the Output Impedance of the amp.  It's not common for that to be stated.  It's very common for the INPUT impedance to be stated.  You take 8ohms (that's the standard used) and divide it by the OUTPUT impedance.  That gives you the Damping Factor.  So, that new Schiit Aegir 2 amp... Jason Stoddard has noted specifically about this number, and stated it is .8ohm.  So, 8ohm / .8ohm = 10 Damping Factor. 

10 Damping Factor is NOT common... it is different... it is something worth trying.  That's my point.

If someone keeps buying amps in different cases with different names on them and they're all pretty much designed the same way... is it any wonder people buy and sell gear all the time because they can't seem to find what sounds "Right"?

Here's the thing in my mind... what process does someone go thru to pick "Amplifier A" vs "Amplifier B".  Is it what they read other people say about it (be careful).  Is it the marketing?  Or is a good way to do it, to look at whether it is fundamentally different in a relevant way compared to what they are already using? 

For instance, if we look at an "AV Receiver"... I would just be looking for "Inputs / Outputs / Functionality".  How a Denon vs Pioneer vs Yamaha vs whatever is going to sound... well, from that standpoint I think they are all pretty similar.

What I have found is that Zero Overall Negative Feedback actually correlates to a difference in sound.  And for me, it's a very positive difference.  It's just more "musical".  I can't measure it.  I can't prove it.  Both things that some will point at as proof that I am kidding myself.  Well, if I like the way an amp sounds because I put a Twinky on it, and I'm convinced the Twinky makes it sound better... well the friggin' Twinky is going on the amp!  This is about MY enjoyment and what I like. 

The truth is, the application of Negative Feedback is important.  It's done to make stuff measure better... but, again, it begs the question... if measuring better is "always better" why does a company bother being committed to "Zero Negative Feedback"? 

I suggest to all to seek out something "different" from what you already have as it relates to this specific measurement.  I have found it's MAGIC, and a lightbulb goes off. Others who have heard stuff like this feel the same way.

[Stercom]

There is a lot of Schiit around.

[Stercom]

I just like hearing what people have and like.  I am building out my system as we speak.  I have some NX-otica's that I am about complete in a few weeks.  I had fredrick build my crossovers and speaker cables.  He does a great job.  Just picked up the crossovers wiring for the speakers and speaker wire at Danny's from being cryo'd.  I have an SMC audio DNA.5 amplifier and ran it on Danny's system and it sounded really good.  I was able to compare it to Danny's reference mono blocks and it held its own.  SMC audio customizes all their equipment.  Now I am going to pick up a DAC and some subs. It's kinda like eating an elephant.

SMC is great equipment. My suggestion is continue to use the SMC. Like others have said perhaps try a NOS R2R DAC from Denafrips or Lampizator. I would also suggest Audio-GD and Border Patrol DACs. The Border Patrol is very reasonably priced, uses Jupiter caps and has a EZ80 tube rectifier and choke input filtering to give you just enough of that tube quality.

[BrandonB]

That's what I've found. Yes.  Damping Factor can be determined by looking at the Output Impedance of the amp.  It's not common for that to be stated.  It's very common for the INPUT impedance to be stated.  You take 8ohms (that's the standard used) and divide it by the OUTPUT impedance.  That gives you the Damping Factor.  So, that new Schiit Aegir 2 amp... Jason Stoddard has noted specifically about this number, and stated it is .8ohm.  So, 8ohm / .8ohm = 10 Damping Factor. 

10 Damping Factor is NOT common... it is different... it is something worth trying.  That's my point.

If someone keeps buying amps in different cases with different names on them and they're all pretty much designed the same way... is it any wonder people buy and sell gear all the time because they can't seem to find what sounds "Right"?

Here's the thing in my mind... what process does someone go thru to pick "Amplifier A" vs "Amplifier B".  Is it what they read other people say about it (be careful).  Is it the marketing?  Or is a good way to do it, to look at whether it is fundamentally different in a relevant way compared to what they are already using? 

For instance, if we look at an "AV Receiver"... I would just be looking for "Inputs / Outputs / Functionality".  How a Denon vs Pioneer vs Yamaha vs whatever is going to sound... well, from that standpoint I think they are all pretty similar.

What I have found is that Zero Overall Negative Feedback actually correlates to a difference in sound.  And for me, it's a very positive difference.  It's just more "musical".  I can't measure it.  I can't prove it.  Both things that some will point at as proof that I am kidding myself.  Well, if I like the way an amp sounds because I put a Twinky on it, and I'm convinced the Twinky makes it sound better... well the friggin' Twinky is going on the amp!  This is about MY enjoyment and what I like. 

The truth is, the application of Negative Feedback is important.  It's done to make stuff measure better... but, again, it begs the question... if measuring better is "always better" why does a company bother being committed to "Zero Negative Feedback"? 

I suggest to all to seek out something "different" from what you already have as it relates to this specific measurement.  I have found it's MAGIC, and a lightbulb goes off. Others who have heard stuff like this feel the same way.

What you are saying makes sense.  What measures well doesn't necessarily make it sound better.  I don't have a very good understanding about electronics although I am interested and I want to learn.  Let me ask you this.  I have heard and read that equipment that uses chokes in the power supply sound better.  I know tube equipment uses chokes and some higher end solid state equipment use chokes.  The guy that builds the mystique DACs says his sauce is based on Chokes and R2R chips but it isn't a tube DAC and they get great reviews from people comparing against several other DACs that aren't reviewers.  Danny has said the Schiit Tyre amp sounded suprisingly good and it has chokes in the power supply.  Do they affect the negative feedback in any way?

[BrandonB]

SMC is great equipment. My suggestion is continue to use the SMC. Like others have said perhaps try a NOS R2R DAC from Denafrips or Lampizator. I would also suggest Audio-GD and Border Patrol DACs. The Border Patrol is very reasonably priced, uses Jupiter caps and has a EZ80 tube rectifier and choke input filtering to give you just enough of that tube quality.

That is exactly what I was thinking.  I am looking at all these DAC's including the Mojo Mystique.  The reviews by individuals who have owned them are great.  The used prices are just a hair out of price range but they are intriguing.

[Jaytor]

What you are saying makes sense.  What measures well doesn't necessarily make it sound better.  I don't have a very good understanding about electronics although I am interested and I want to learn.  Let me ask you this.  I have heard and read that equipment that uses chokes in the power supply sound better.  I know tube equipment uses chokes and some higher end solid state equipment use chokes.  The guy that builds the mystique DACs says his sauce is based on Chokes and R2R chips but it isn't a tube DAC and they get great reviews from people comparing against several other DACs that aren't reviewers.  Danny has said the Schiit Tyre amp sounded suprisingly good and it has chokes in the power supply.  Do they affect the negative feedback in any way?

Chokes, coupled with good capacitors, in the power supply do an excellent job of filtering out power supply noise and hum, including noise generated by the rectifier switching and transformer resonances. Most  amplifiers do not use active regulation, so a power supply employing chokes can do a nice job cleaning up the signal.

SET amps have fairly poor power supply noise rejection, so good quality power supply filtering is key. Push pull amps, can cancel out a fair amount of the power supply noise, so it's a little less important here, but still helpful.

Global negative feedback will improve the power supply rejection, so is often used with lower cost amplifiers which can't afford the components necessary to do good quality filtering. Global negative feedback will also improve the amplifiers ability to maintain the correct output voltage under varying load conditions, lowering the output impedance and making the amplifier more of a voltage source instead of a current source.

But global negative feedback also introduces its own problems. This is mostly because it is much more effective at lower frequencies than higher frequencies, so it will reduce the lower order harmonics more than the higher order harmonics. This tends to make the amp sound brighter and harsher. This may sound like it is providing more detail, but it is primarily emphasizing the higher harmonics.

Low order harmonics (particularly second and third) do an excellent job of masking the higher order harmonics, so reducing their dominance will result in worse sound (in my opinion) but will also reduce the measured THD.

Many have attributed higher second and third order distortion to a more natural and spacious sound and a deeper sound stage. This is why so many audiophiles love their SET amps with no feedback (I'm one of them).

As noted above, the big downside of no global feedback with tube amps is the output impedance can be quite high (and thus low damping factor). This can make the bass sound bloated and sloppy, depending on the speakers used. Some people are ok with this, or even prefer it.

Personally, I think the best of both worlds is to use a zero-global-feedback SET amp for the upper bass on up and use an amp with a high damping factor for the lower bass.

It is possible to measure the effects of global negative feedback and it's influence on the distribution of harmonics. The best sounding amps, in my opinion, are those that have a steadily decreasing prominence of harmonics in the distortion profile (e.g. 2nd is higher than 3rd, 3rd is higher than 4th, etc.). But again, if the amplifiers damping factor is low, the speakers impedance vs frequency can greatly affect the tonal balance, and the bass is likely to be less well controlled.

[BrandonB]

Chokes, coupled with good capacitors, in the power supply do an excellent job of filtering out power supply noise and hum, including noise generated by the rectifier switching and transformer resonances. Most  amplifiers do not use active regulation, so a power supply employing chokes can do a nice job cleaning up the signal.

SET amps have fairly poor power supply noise rejection, so good quality power supply filtering is key. Push pull amps, can cancel out a fair amount of the power supply noise, so it's a little less important here, but still helpful.

Global negative feedback will improve the power supply rejection, so is often used with lower cost amplifiers which can't afford the components necessary to do good quality filtering. Global negative feedback will also improve the amplifiers ability to maintain the correct output voltage under varying load conditions, lowering the output impedance and making the amplifier more of a voltage source instead of a current source.

But global negative feedback also introduces its own problems. This is mostly because it is much more effective at lower frequencies than higher frequencies, so it will reduce the lower order harmonics more than the higher order harmonics. This tends to make the amp sound brighter and harsher. This may sound like it is providing more detail, but it is primarily emphasizing the higher harmonics.

Low order harmonics (particularly second and third) do an excellent job of masking the higher order harmonics, so reducing their dominance will result in worse sound (in my opinion) but will also reduce the measured THD.

Many have attributed higher second and third order distortion to a more natural and spacious sound and a deeper sound stage. This is why so many audiophiles love their SET amps with no feedback (I'm one of them).

As noted above, the big downside of no global feedback with tube amps is the output impedance can be quite high (and thus low damping factor). This can make the bass sound bloated and sloppy, depending on the speakers used. Some people are ok with this, or even prefer it.

Personally, I think the best of both worlds is to use a zero-global-feedback SET amp for the upper bass on up and use an amp with a high damping factor for the lower bass.

It is possible to measure the effects of global negative feedback and it's influence on the distribution of harmonics. The best sounding amps, in my opinion, are those that have a steadily decreasing prominence of harmonics in the distortion profile (e.g. 2nd is higher than 3rd, 3rd is higher than 4th, etc.). But again, if the amplifiers damping factor is low, the speakers impedance vs frequency can greatly affect the tonal balance, and the bass is likely to be less well controlled.

Does an amplifier create negative feedback with op amps?  I assume using a high pass filter with servo subs is a good idea with amps with no negative feedback.

[Jaytor]

Does an amplifier create negative feedback with op amps?  I assume using a high pass filter with servo subs is a good idea with amps with no negative feedback.

An amplifier implements global negative feedback by taking the a portion of the output and feeding it into a point at the input that is the opposite phase as the output. If the amplifier is inverting, this can just be summing a portion of the output with the input. By portion, I mean that a resistor divider network that reduces the level of the output based on the amount of feedback desired.

Using feedback will reduce the effective overall gain of the amplifier. So if the "open-loop" gain of an amplifier is 30db, and 10db of negative feedback is applied, then this will reduce the output by 10db. So the amplifier must be designed to have higher open loop gain to compensate. Open loop gain refers to the gain of the amp without any feedback applied.

OpAmps are designed to almost always work with negative feedback. Opamps have very high open loop gain (typically 160db or even higher), but that gain falls rapidly with frequency. The only way to get flat response is to employ a significant amount of negative feedback. But this high open loop gain makes them very effective for use in filters since their response is determined by how the feedback network is constructed, so they are often used for crossovers, phono amplifiers, brick-wall filters in DACs, etc. The term "opamp" comes from Operational Amplifier because these were originally designed for use in analog computers.

Audio equipment employing modern opamps can sound quite good, but if you are going after a warmer sound with higher amounts of low-order harmonics, a discrete circuit (either tube or solid state) is probably a better choice. Although employing opamps for filters as part of the audio chain can be very effective.

If you are using a servo sub then using a high-pass filter before your main amp will reduce the amount of low frequency information it has to handle. But this will also cause phase shifts in the audio signal at frequencies well above the -3db point of the high-pass filter (particularly a simple first order filter). So it's a bit of a compromise. If you are worried about the main amplifier's headroom (i.e., your main speaker's sensitivity is such that you are ever likely to be pushing the amplifier to near clipping), then I think using a high-pass filter is a good idea. If you have plenty of power, it's a tougher call but still might be worth doing since it will reduce the excess power that your low-frequency driver (in your main speakers) must handle.

Also, keep in mind, that no analog filter is perfect. In addition to phase shifts, at a minimum you'll be passing the signal through another capacitor with its own imperfections.

[jmimac351]

What you are saying makes sense.  What measures well doesn't necessarily make it sound better.  I don't have a very good understanding about electronics although I am interested and I want to learn.  Let me ask you this.  I have heard and read that equipment that uses chokes in the power supply sound better.  I know tube equipment uses chokes and some higher end solid state equipment use chokes.  The guy that builds the mystique DACs says his sauce is based on Chokes and R2R chips but it isn't a tube DAC and they get great reviews from people comparing against several other DACs that aren't reviewers.  Danny has said the Schiit Tyre amp sounded suprisingly good and it has chokes in the power supply.  Do they affect the negative feedback in any way?

I know very little about electronics as well, but I'm not bad at connecting dots.  I listen, then connect more dots. If I still had my Magnepan 3.7i speakers, I wouldn't hesitate to try the Tyr amps.  In fact, I almost did.  The choke input helps with dynamics as it's an extra transformer, instead of power supply caps.  It's an "old school" way of doing it, and more costly.  I would not buy Tyr amps for use with NX-Otica or NX-Treme.

I am going to buy an Aegir 2 when it's released, and I don't need it.  I think it's very different and I want to try it.  If I had a pair of NX-Otica and were starting from scratch, I would buy one of those and let the subs take care of themselves. If I liked the Aegir 2 sound quality (which is the ONLY reason I am buying one... I think it's going to be excellent) and wanted more power, I'd buy a second one and run them as mono blocks.  100w/ch into NX-Otica would be good enough for most people.  If I still wanted more power, I would sell the NX-Otica, buy The Bully, Tyr, and admit to myself that I want an AC/DC concert in my living room. 

Actually, you still wouldn't need to buy Tyr amps with The Bully... you've still got the high sensitivity advantage and just running the MTM, and you've got a servo sub built in.

I'm drifting away from speakers that "need" a bunch of power to drive them. I don't listen at high levels... but the stuff I have right now will still JAM and put on a show...

[KTS]

Brandon,
I am not nearly as advanced as the majority of the extremely helpful members, but I like the DIY Audio amps. So far I like both the F3 and the Aleph J amps in the process of building an M2X. I also use the Schiit Vidar (a nice amp). I like what the Aleph J does to the sound overall currently. It has a good soundstage with loads of imo accurate detail. My pre is the Schiit Freya + and my DAC is the Denafreps Aries.

Thank you for asking this question, I am learning for everyone’s responses.

Kelly

[nlitworld]

Thank you for asking this question, I am learning for everyone’s responses.

This forum is great. I've learned more on this thread in 3 days than 3 months of frequenting the other forums.  This topic and the fine print details that make the differences in components are really super interesting to read about. I haven't heard every type of amp listed here but with reading through this thread and knowing where I have liked my system's sound qualities changing over time, it makes for very useful info on making educated decisions on future purchases.

Now I did have a question since negative feedback is such a big part of this discussion. If an amp currently employed some db of negative feedback, could it be modified to be less or none at all without having a Chernobyl meltdown? I guess that's probably an amp specific try it and 🤞 situation though.

[Jaytor]

This forum is great. I've learned more on this thread in 3 days than 3 months of frequenting the other forums.  This topic and the fine print details that make the differences in components are really super interesting to read about. I haven't heard every type of amp listed here but with reading through this thread and knowing where I have liked my system's sound qualities changing over time, it makes for very useful info on making educated decisions on future purchases.

Now I did have a question since negative feedback is such a big part of this discussion. If an amp currently employed some db of negative feedback, could it be modified to be less or none at all without having a Chernobyl meltdown? I guess that's probably an amp specific try it and 🤞 situation though.

A lot of amplifiers, particularly direct couple solid state amps, rely on global negative feedback to achieve stability and maintain the DC operating point. You might be able to get away with it on a tube amp with an output transformer, but even in this case you should be careful. Unless you really understand how the amplifier works, I would strongly discourage this. You could do serious damage to your speakers.

[BrandonB]

Brandon,
I am not nearly as advanced as the majority of the extremely helpful members, but I like the DIY Audio amps. So far I like both the F3 and the Aleph J amps in the process of building an M2X. I also use the Schiit Vidar (a nice amp). I like what the Aleph J does to the sound overall currently. It has a good soundstage with loads of imo accurate detail. My pre is the Schiit Freya + and my DAC is the Denafreps Aries.

Thank you for asking this question, I am learning for everyone’s responses.

Kelly

I know Tyson is a big fan of the Aleph J and I have heard great things about it.  I too am attracted to the DIY and boutique market.  I am learning a bunch from this thread, just wish I had a stronger background in electronics. 

[mkrawcz]

I know Tyson is a big fan of the Aleph J and I have heard great things about it.  I too am attracted to the DIY and boutique market.  I am learning a bunch from this thread, just wish I had a stronger background in electronics.

The AlephJ is definitely up there in sound quality for SS amps.

[Jaytor]

Nelson Pass introduced a new design variant of the F5 at Burning Amp last year. He calls it the F5m, I think the m standing for "minimum cost" or something like that. It is a very simple circuit that is more second harmonic prominent, and has no capacitors in the circuit. Here's the schematic of the basic circuit.



There will be a kit available on diyaudiostore.com, expected in the next week. This would be a great design to start with.

I am working on a build based on this design, using my own custom PCBs. My design adds some additional features including a DC Servo circuit, an optically coupled speaker protection circuit, and a balanced input. I'm building two stereo amps to try biamping my Line Forces.

[Tyson]

I know Tyson is a big fan of the Aleph J and I have heard great things about it.  I too am attracted to the DIY and boutique market.  I am learning a bunch from this thread, just wish I had a stronger background in electronics. 

Look for them on the used market and you can find some really good deals on the Aleph J.