[alota]

Quote:

And I totally agree that people spend too much time reading about their gear. There's a certain kind of person who will believe anything they're told and buy from anyone who is friendly to them. Insane. They'll wade through pages of reviews but not make the least effort to learn about electronics or figure things out. I've seen five year-olds that are more inquisitive.

in the past, i was one of those people.
today(and i thank head-fi for this),i understand many more things

 

[Jh8cw]

Uncle Erik,
 
Alright. I did some research on my own. So basically you are most concerned about this bit:  "the use of two aerospace designed switching power supply ( followed by a redundancy of traditional capacitance)  ensure high current, highest reliability, no EMI or any kind of emission and the cleanest output current..."  
 
It's not possible for the switching supply to be designed with proper shielding? 

 

[audiogamma]

Rudi's "research"
 
http://www.audiores-all.com/audiories-all.com/Home.html
 
http://www.amazon.com/gp/help/seller/at-a-glance.html?ie=UTF8&isAmazonFulfilled=1&seller=A1QIZTZUF2N75K

 

[visualguy]

Quote:

They'll wade through pages of reviews but not make the least effort to learn about electronics or figure things out. I've seen five year-olds that are more inquisitive.

Admitting ignorance and relying on experts beats gaining some superficial knowledge that's just enough to be dangerous. I don't have any good reason to believe that designers like Jeff Rowland don't know what they're doing. I can't gain the needed knowledge and experience to evaluate their design choices from some crash course in electronics, unfortunately... All I know is that the audio electronics that I own with switching power supplies sound perfectly fine to me.
 

 

[visualguy]

 
Quote:

So JR goes from multi hundred watt power amps biased high into class A to being all about green energy suddenly?  Sounds like a gimmick to me.

He mentions other good qualities: low heat, quiet operation under all AC line conditions (no hum), compact size, etc.
 

 

[khaos974]

Well, considering that his D class amp are ICE Power modules without much customization done to the electronics side, I'd said their R&D for D class amps is non existent.

 

[visualguy]

     Quote:

Well, considering that his D class amp are ICE Power modules without much customization done to the electronics side, I'd said their R&D for D class amps is non existent.

He isn't in the business of building better class D amp modules than B&O - they already put a huge investment in this R&D, and their modules are excellent. Not sure what your point is...
 

 
 

 

[khaos974]

     Quote:

He isn't in the business of building better class D amp modules than B&O - they already put a huge investment in this R&D, and their modules are excellent. Not sure what your point is...
 

 
 

The same modules can be found in much less expensive amps, not to mention that they can be bought for less than $500 for DIY purposes.

 

[visualguy]

 
Quote:

The same modules can be found in much less expensive amps, not to mention that they can be bought for less than $500 for DIY purposes.

The JR class D amps aren't the best value for the money unless you're really into the cosmetics and build quality which are superb (again, I'm not saying it's worth the money.)
 
Value-for-money isn't really there in my personal opinion in high-price audio electronics in general regardless of whether the modules and power supplies are off-the-shelf or designed in-house.
 
It's not just diminishing returns - there are basically no returns beyond a certain level, and this level is typically reachable at the low-to-mid 4 figures at the most... Only speakers are worth spending more money than that for in my experience.
 
Anyway, this is a different discussion.
 

 

[khaos974]

 

The JR class D amps aren't the best value for the money unless you're really into the cosmetics and build quality which are superb (again, I'm not saying it's worth the money.)
 
Value-for-money isn't really there in my personal opinion in high-price audio electronics in general regardless of whether the modules and power supplies are off-the-shelf or designed in-house.
 
It's not just diminishing returns - there are basically no returns beyond a certain level, and this level is typically reachable at the low-to-mid 4 figures at the most... Only speakers are worth spending more money than that for in my experience.
 
Anyway, this is a different discussion.
 

Actually, for the price JF charges, he could have had an much more innovative and better product, like the Devialet D-Premier. It costs $15000 and possibly doesn't sound better than a good $2000 amp but it measures better on every possible parameter than the JF D class amp except power.

 

[visualguy]

Quote:

Actually, for the price JF charges, he could have had an much more innovative and better product, like the Devialet D-Premier. It costs $15000 and possibly doesn't sound better than a good $2000 amp but it measures better on every possible parameter than the JF D class amp except power.

ICEpower measurements look really good:
 
http://www.icepower.bang-olufsen.com/files/solutions/icepower250asx2_datasheet_1_1.pdf
 
What am I missing?
 
They also sound great - I have a couple of amps based on these modules.
 

 

[khaos974]

I'm not saying that The ICE modules are bad, I'm saying that JF provides no added value beyond a nice faceplate.

 

[DaveBSC]

 
He mentions other good qualities: low heat, quiet operation under all AC line conditions (no hum), compact size, etc.
 

Rowland sells chip amps in $7500 boxes. As far as I'm concerned his credibility is near zero. The only Class D amp I think is remotely good is the Spectron, which has a big old linear transformer in it. The refinement of the B&O amps, particularly in the treble region is pretty bad.

 

[visualguy]

 
Quote:

The only Class D amp I think is remotely good is the Spectron, which has a big old linear transformer in it. The refinement of the B&O amps, particularly in the treble region is pretty bad.
 

Any idea why this treble problem isn't showing up in measurements? The datasheet shows awesome performance throughout the audible frequency range and beyond...
 

 

[DaveBSC]

 
Any idea why this treble problem isn't showing up in measurements? The datasheet shows awesome performance throughout the audible frequency range and beyond...
 

Measurements can't tell you everything. A while back when reading a review of the new Levinson flagship amplifier which is sort of a digital amp, there was an explanation of how ordinary Class D amps work, why they don't sound that good, and what Levinson did to fix the issue. IIRC, it was something to do with the way the transistors switch on and off. I'm not talking about the UHF noise problem, I think that's been at least mostly dealt with. It was something to do with the switching process itself, leaving gaps when the transistors are OFF-OFF, which leads to the dull, unrefined highs of Class D amps, and the mediocre soundstage.