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In Reply to: RE: My quote was accurate. And it explains well why he makes a variety of amps... posted by kuribo on September 21, 2015 at 05:43:51
Let's (correctly) attribute his comments, shall we?
These quotes are from Audio Distortion and Feedback
" Negative feedback can reduce the total quantity of distortion, but it adds new components on its own, and tempts the designer to use more cascaded gain stages in search of better numbers, accompanied by greater feedback frequency stability issues.
The resulting complexity creates distortion which is unlike the simple harmonics associated with musical instruments, and we see that these complex waves can gather to create the occasional tsunami of distortion, peaking at values far above those imagined by the distortion specifications."
Follow Ups:
nt
try it! you know you want to!
He uses feedback...
Not surprisingly, nuance eludes you in multiple areas.
What he uses is "small" amounts for stability. There is quite a difference between small amounts and heroic (80 db) used by your hero. Let's follow more of his thinking, shall we?
This is from the Xs brochure . (Yes, Virginia that is another link!)
" They found the sound of the [zero feedback] SIT to have truly remarkable properties and it was quickly decided 'Whatever this is, we need a way to bottle it'. Not only did we need to bottle it, but we needed to put it around a much bigger bottle.
In a subjective area where engineering has limitations , it is extremely useful if you can recognize what you want when you hear it. It you have an example of the sound you are looking for, there is great advantage.
Because the sonic quality was so striking , it became easier to discover what modifications to the circuit would make it go away, and by the process of varying the design and listening to the result ...A small amount of feedback was employed around the output stage
nt
try it! you know you want to!
and have done so several times in the past month or so - I'll leave you with his take on switching amps . BTW, the pic is one he built. :)
As with my previous four posts, I'm linking to the source to eliminate confusion (on your part). Let's review his thoughts:
" Class D amplifiers are switches with tons of feedback.
It's amazing they work as well as they do. "
But nice straw man.....we already know he believes in feedback and that amp choice is subjective....
The ncore will be there when you tire of your distortion....
try it! you know you want to!
I don't know about that one Kirby, Putzeys hasn't done anything besides switching amps since he got out of school.Pass on the other hand has a much more diverse and successful background. He is a cult legend for a reason.
Class D isn't black magic, heck, even I could cobble one together, as mentioned before it is nothing new or exotic.
It is challenging, in the sense that it sucks for audio.Back on topic, which believe it or not is not Kirby's class D amp...
Here are some interesting quotes from Pass's wikpedia page:"The SIT chip combines a square-law input character with a low impedance output to form the only solid-state gain device, which Pass claims, "behaves like a triode tube.""
"The point of the SIT is that it behaves like a triode but at lower voltages and higher currents, so it doesn't need a matching transformer to deliver power to 8 Ohms. "
"SITs have a curve which looks a lot like a triode vacuum tube; low at first and climbs steadily. The distortion curve is similar, a steady rise instead of a valley with high distortion at both ends." (Which is what Morricab stated when he said SS made more distortion at low volumes.)
So, I would consider Pass's SIT amps as "SOTA", not to be confused however with the "pinnacle" which was developed by De Forest over 100 years ago.
Everything since then, has been a compromise in one way or another.
△ᴉʇɐuᴉɯnllI oᴉpn∀△
Edits: 09/22/15
Putseys started designing and building tube amps. He has moved on with spectacular success.
Pass' products are all ss as far as I know. He once tried a class d amp but couldn't get it to perform well.
And yes, building a class d amp is not hard. Building a good one is. Just ask those who have tried.
try it! you know you want to!
Well maybe you know more about Putseys then is public record?"Early life
He graduated cum laude at the National Technical School for Radio and Film on the subject of power stages for switching audio amplifiers. Worked for 10 years at the Philips Applied Technologies Lab in Leuven, Belgium, where he developed various digitally and analogue controlled class D amplifiers, noise shapers and modulation methods, and invented among others the "UcD" class D circuit."
"Career
In 2005 he left Philips to divide his time between Grimm Audio and Hypex. Current activities include designing high-performance discrete AD/DA converters and analogue signal processing circuits, DSP algorithms, class D power amplifiers and switch-mode power supplies. He holds several patents in the fields of digital audio and power conversion and has published extensively in these and related domains."
It doesn't say anything about tube amps...
△ᴉʇɐuᴉɯnllI oᴉpn∀△
Edits: 09/22/15
Here's one
He dabbled briefly as a teenager.
Well, you got me.
I guess Putzey has the same pedigree as hundreds of others over at DIYAudio after-all.
△ᴉʇɐuᴉɯnllI oᴉpn∀△
the section about his music collection:
"Along another wall in the living room are shelves with an eclectic mix of a couple of hundred CDs..."
Makes perfect sense that analog and high resolution are absent.
How many CD's in your collection ..... ?
along with another 600 vinyl and several dozen high rez albums.
I have heard the Grimm active speaker system now several times here in Switzerland and each time it is totally clear and precise and STERILE and UNmusical like hell. I can't stand more than a few minutes in the room with such an utterly unmusical "mr. Spock" like sound. Grimm indeed...
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