[StefanJK]

 
ayre, audio-gd, bakoon and a few other companies make audio products that have no feedback of any kind
and therefore have no TIM. All are based on multiple Wilson current mirrors.

Is TIM (Transient InterModulation distortion) an issue for low feedback amps nowadays?  Any measurements?  I've heard the theory, to stay on the thread topic, that the Rag is 'good' since it has low TIM.  Any measurements on this (relative to other amps, including Wilson current mirrors)?  

 

[45longcolt]

   
There's no such thing as too much excess!

 
My old English teacher would have something to say about that sentence, though I'm sure your tongue was in your cheek. But, as the Grateful Dead once sang, "Too much of everything is just enough." Or Oscar Wilde - "Nothing succeeds like excess." So you're in "good" company...or at least fun company! 

 

[jacal01]

  ayre, audio-gd, bakoon and a few other companies make audio products that have no feedback of any kind and therefore have no TIM. All are based on multiple Wilson current mirrors.
 
now getting something like this into a portable is going to be tough.

 
Do you happen to know what kind of gain current mirrors Krell and Questyle employ?  Also Wilson?
 
Also, would a transconductance or transimpedance opamp qualify as some type of current mirror/controlled gain circuit for portable amp design?  Just asking.

 

[Chris J]

absolutely not true.

ayre, audio-gd, bakoon and a few other companies make audio products that have no feedback of any kind
and therefore have no TIM. All are based on multiple Wilson current mirrors.

now getting something like this into a portable is going to be tough.

Don't go crazy on us, big guy.

The parasitic collector to base capacitance would be considered a source of local feedback in a simple BJT gain stage.

 

[jcx]

...audio products that have no feedback of any kind and therefore have no TIM...

false statement, false correlation
 
every active circuit in a amp will have a hard slew limit from device, bias and supply limitations - feedback or no and will distort for some value of "Transient" input
 
"soft" slew limiting, gain/phase changing with dynamic signal cause FM Intermodulation products and are also usually lumped in "TIM" too
 
"no feedback" amps have "TIM" distortion mechanisms, measureable "FM" Intermodulation Products
 
any nonlinear C, modulating gain working into a complex load will
 
 
and global feedback can be used without increasing "TIM" - just use a linear front end, attend to stage bias current demand, use 2-pole compensation
 
 
Bob Cordell clearly refuted Mati Otala's "high feedback amp" TIM analysis, prescriptions 30+ years ago - building a custom quadrature resolving IMD distortion analyzer and measuring "TIM" distortions down to 10s picoseconds in his high feedback, global loop gain  http://www.cordellaudio.com/poweramp/mosfet.shtml
 
more recently in AES conference papers Ron Quan has been revisiting TIM in audio op amps with different 3-tone test derived from RF amp practice and his own purpose built analyzer hardware - he had to look at generic 30 year old monolithic op amps, worse than the TL072 to get result above his instrument's noise floor
http://www.aes.org/e-lib/online/search.cfm

 

[jcx]

absolutely not true.
 
ayre, audio-gd, bakoon and a few other companies make audio products that have no feedback of any kind
and therefore have no TIM. All are based on multiple Wilson current mirrors.
 
now getting something like this into a portable is going to be tough.
 

I see kevin's on a roll here
 
only audiophile marketing types don't recognize emitter/source/cathode followers, degeneration as examples of local negative feedback - you will fail your Uni EE analog design courses if you don't use feedback formulas, Blackman's Theorem in analyzing these circuits

 

[anetode]

 
Well, you already have a Ragnarok, which many would consider the best amp in the world for the HE-6. You could get what some — myself included — would say is the best overall headphone/amp combo in the world, even better than the SR-009, for $1300 more (and likely sell your HD 800 for most of that).

 
How's your high frequency hearing? HE-6 definitely has the bass and lower mids covered, but the 009 beats it handily in treble smoothness and extension and both the HD800 and 009 beat it in resolution/detail retrieval. Not to mention soundstage, where most good open dynamics have the upper hand by default.
 
edit to relate this at least somewhat to the thread: I tried the Rag beta at a meet earlier this year and while it is a very good solution for power-hungry orthos, it doesn't exactly fix the HE6s issues as much as accentuate its strengths when presented with the extra headroom.

 

[Chris J]

false statement, false correlation

every active circuit in a amp will have a hard slew limit from device, bias and supply limitations - feedback or no and will distort for some value of "Transient" input

"soft" slew limiting, gain/phase changing with dynamic signal cause FM Intermodulation products and are also usually lumped in "TIM" too

"no feedback" amps have "TIM" distortion mechanisms, measureable "FM" Intermodulation Products

any nonlinear C, modulating gain working into a complex load will


and global feedback can be used without increasing "TIM" - just use a linear front end, attend to stage bias current demand, use 2-pole compensation


Bob Cordell clearly refuted Mati Otala's "high feedback amp" TIM analysis, prescriptions 30+ years ago - building a custom quadrature resolving IMD distortion analyzer and measuring "TIM" distortions down to 10s picoseconds in his high feedback, global loop gain  http://www.cordellaudio.com/poweramp/mosfet.shtml

more recently in AES conference papers Ron Quan has been revisiting TIM in audio op amps with different 3-tone test derived from RF amp practice and his own purpose built analyzer hardware - he had to look at generic 30 year old monolithic op amps, worse than the TL072 to get result above his instrument's noise floor
http://www.aes.org/e-lib/online/search.cfm

I see kevin's on a roll here

only audiophile marketing types don't recognize emitter/source/cathode followers, degeneration as examples of local negative feedback - you will fail your Uni EE analog design courses if you don't use feedback formulas, Blackman's Theorem in analyzing these circuits

Thank you,
My thoughts exactly.

 

[marcoarment]

   
How's your high frequency hearing? HE-6 definitely has the bass and lower mids covered, but the 009 beats it handily in treble smoothness and extension and both the HD800 and 009 beat it in resolution/detail retrieval. Not to mention soundstage, where most good open dynamics have the upper hand by default.

 
I have average hearing for my age of 32 — I can hear 15 kHz loud and clear, 16 kHz at reduced volume, and not 17+ kHz. My wife has a similar pattern shifted about 2 kHz higher, and she had the same opinions of these three headphones.
 
All I can say is all I did say — this is what I heard from spending a lot of time with each of these three headphones, and this is my opinion of them, which differs substantially from yours. I agree on soundstage — HD 800 is king there, with 009 and HE-6 being below it (and similar to each other). But I'd never say that the 009 and 800 are smoother or substantially better in high-frequency extension and detail — in those areas, I found the 800 to be above-average (but not excellent) and the 009 and HE-6 to be excellent (and nearly indistinguishable). Where I hear the HE-6 beating the 009 handily is in achieving that detail without harshness — the 009 is quite harsh, which is probably why everyone keeps trying to throw tubes at it to make it sound the way they think it should.
 
Looking at the gear in your profile and seeing the LCD-3, 800, and 009, but no HE-6, is it safe to assume that you haven't spent a lot of time with the HE-6 at home? I don't ask to be inflammatory, just as I'll give you the benefit of the doubt that asking about my hearing wasn't meant to be. The reason I ask is that the qualities and relative strengths and weaknesses you're attributing to the HE-6 sound a lot like how I'd judge the LCD-3 relative to the 009, with its silky-smooth and detailed "bass and lower mids" but rolled-off high end that reduces perceived "resolution/detail retrieval".
 
But as I was agonizing over whether I should sell my very expensive 009 setup (at a substantial loss) after discovering the HE-6, I spent a lot of time testing them back to back, trying to justify keeping the 009. I, too, thought that the 009 should offer better high-end and detail, since that's what electrostatics are supposed to offer. But that simply didn't match what I heard — I thought the HE-6 matched the 009's strengths toe-to-toe, and surpassed it in a few areas such as bass, midrange smoothness, and adaptability to more music.

 

[preproman]

   
I have average hearing for my age of 32 — I can hear 15 kHz loud and clear, 16 kHz at reduced volume, and not 17+ kHz. My wife has a similar pattern shifted about 2 kHz higher, and she had the same opinions of these three headphones.
 
All I can say is all I did say — this is what I heard from spending a lot of time with each of these three headphones, and this is my opinion of them, which differs substantially from yours. I agree on soundstage — HD 800 is king there, with 009 and HE-6 being below it (and similar to each other). But I'd never say that the 009 and 800 are smoother or substantially better in high-frequency extension and detail — in those areas, I found the 800 to be above-average (but not excellent) and the 009 and HE-6 to be excellent (and nearly indistinguishable). Where I hear the HE-6 beating the 009 handily is in achieving that detail without harshness — the 009 is quite harsh, which is probably why everyone keeps trying to throw tubes at it to make it sound the way they think it should.
 
Looking at the gear in your profile and seeing the LCD-3, 800, and 009, but no HE-6, is it safe to assume that you haven't spent a lot of time with the HE-6 at home? I don't ask to be inflammatory, just as I'll give you the benefit of the doubt that asking about my hearing wasn't meant to be. The reason I ask is that the qualities and relative strengths and weaknesses you're attributing to the HE-6 sound a lot like how I'd judge the LCD-3 relative to the 009, with its silky-smooth and detailed "bass and lower mids" but rolled-off high end that reduces perceived "resolution/detail retrieval".
 
But as I was agonizing over whether I should sell my very expensive 009 setup (at a substantial loss) after discovering the HE-6, I spent a lot of time testing them back to back, trying to justify keeping the 009. I, too, thought that the 009 should offer better high-end and detail, since that's what electrostatics are supposed to offer. But that simply didn't match what I heard — I thought the HE-6 matched the 009's strengths toe-to-toe, and surpassed it in a few areas such as bass, midrange smoothness, and adaptability to more music.

WOW someone who I can relate to. 

 
But seriously.  All three headphones are great on their best matching amps (what ever those amps are for that individual).  In saying that I can't for the life of me see where the HD800 beats the HE-6 in resolution or detail retrieval.  Soundstage height, width and depth (yes but maybe not all three) and imaging maybe so.  However, from sub Bass to lower Mids on up to the lower treble, the overall weight of the music the HE-6 beats both the 009s and the HD800 IMO..  I like the 009s for it's utmost crystal clear clarity - that's about it.
 
Still, I will never sell my HD800s again - because the HD800s on the EC 445 is something very special.  

 

[commtrd]

Well my beloved Ragnarok has bit the dust. RA 4257 to send it back for diagnosis and repair. Just died for no apparent reason. Bummer. It was a really sweet three weeks I spent with her... Quite the tempestuous love affair!  ;0)
 
Good thing I still have my Mjolnir. Would be freaking out with no music at all.

 

[Duncical]

  Well my beloved Ragnarok has bit the dust. RA 4257 to send it back for diagnosis and repair. Just died for no apparent reason. Bummer. It was a really sweet three weeks I spent with her... Quite the tempestuous love affair!  ;0)
 
Good thing I still have my Mjolnir. Would be freaking out with no music at all.

Damn that sucks dude.

 

[commtrd]

Well it happens. Hopefully get the rok back quickly and totally functional.

 

[goldendarko]

  Well it happens. Hopefully get the rok back quickly and totally functional.

Dang, sucks to hear, mine stopped working a few weeks after i got it too, hopefully there's nothing going on that will affect the long term viability of this great amp. Let us know what the diagnosis is when they get it back, I'm curious to hear.

 

[cizx]

Two failures.  Schiit's over.
 

 
Seriously, though, I hope it's nothing systemic.  Two bad amps out of all the people here who've reported getting them isn't horrible, but it isn't grand either.