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[zenmastering]

Dave,

Your experience with the 'break-in' of the S300 mirrors my own with the Ref1000. Same actually with the Hafler 9505 on the Lipinskis.

I noticed quite a difference in the sound of the Ref1000 between day one and two of my tests, less so as the week went on. Originally the top end was quite 'pinched' sounding (kinda like a  small high-Q boost at 12k). Having the Pass Labs amps there to refer back to, helped in noticing the changing character over time.  

I find that equipment break-in is a two way street: The gear is changing and I'm also adapting to it. This isn't alswys the easiest process to track.

Jaakko, the Hypex modules are easily available in small quantities, but I haven't found a similar source for the ICE Power modules yet. (Nor have I looked all that hard.)

Best,

Graemme

[chrisj]

Viitalahde wrote on Thu, 17 August 2006 11:48

One thing, it's often said that the first Watts are the best in Class A amps. How about Class D? I can't imagine the sound to really change much with 10w or 100w output, from the technical POV.

The D100s don't come with a lot of extra space and lushness. It's like the sonic 'space' can be very small and detailed, or outlandishly big and dry. Large transient spikes and sonic events poke out without any restriction. One result of this is that ITB digital mixes can sound awfully digital- the stuff without any 'glue' totally sounds fragmented and discrete, extraneous sounds which aren't blended very well sticking out like a shard of glass sticking out of water- nothing specially wrong with the transparency, but the lack of cohesiveness can be rendered with jarring incongruity.

I like that a lot better than what I had (which 'hung together' better), and it seems to correspond with your expectation. It does make you work harder though.

[Rivendell61]

Jaakko,
You asked about the Class D 'first watt'.  Here is a link to the data sheet on the Hypex UcD 400:
http://www.hypex.nl/docs/UcD400_datasheet.pdf

If you scroll down to the AP2 plots and look at the THD vs Power at sub one watt it is quite nice (c. .0005).  Also note the THD vs Frequency: flat (and note which usage Bruno puts first under 'Applications'....).

The 400's are the modules used in the CIAudio D-100 which Chris has.  But you can also buy the bits (modules, power supply, etc) right from the Hypex web site and put your own together.

Mark

[maxdimario]

class d amps with a digital input would make more sense, since they are PWM amps.. right?..

are there any around?

[ammitsboel]

maxdimario wrote on Fri, 18 August 2006 11:09

class d amps with a digital input would make more sense, since they are PWM amps.. right?.. are there any around?

Not necessarily.
The PCM to PWM conversion can be very bad.
The Analog to PWM seems like a simpler way to do it.

Viitalahde wrote on Thu, 17 August 2006 11:48

One thing, it's often said that the first Watts are the best in Class A amps. How about Class D? I can't imagine the sound to really change much with 10w or 100w output, from the technical POV.

That's right, in class D all the watts are useless and they don't change much from the first to the last.
-sorry couldn't resist

H

[JGreenslade]

Viitalahde wrote on Thu, 17 August 2006 16:48

One thing, it's often said that the first Watts are the best in Class A amps. How about Class D? I can't imagine the sound to really change much with 10w or 100w output, from the technical POV.

I wonder if you're confusing Class A/B amps with Pure Class A here?

A typical Class A/B amp may have 15-30 watts worth of bias before it strays into Class B operation; unless you master at loud volumes in a large room, you should be in the Class A region most of the time.

A pure Class A amp is an environmental tragedy, and I can't think of any amp that has more than around 30 watts of Pure Class A in the current marketplace (a typical 30 watts Class A amp will likely yield 300+ in Class A/B).

Over the years, OEMs have implemented many systems to try and extend Class A performance, without the efficiency concerns (Class S and "Current Dumping" being examples).

The maximum theoretical efficiency of a Class A output stage is around 19% - with real-world programme material, this is likely to drop to single figures. If you then factor in the PSU efficiency (unlikely to be above 60%), you'll realise that to get 30 watts of Class A, you'll probably have to burn 175-250 watts of power - permanently - per channel...  

Even Krell's "Master Reference" (cost around $150USD) isn't "Pure Class A"; it uses Krell's "Plateau Bias" system, which is marketing speak for a sliding bias system that analyses incoming peaks and biases accordingly.

Looking at your efforts with the DIY Sontec, Jaakko, I would suggest you're in a prime position to build a DIY amp to your own 'spec if you want to save expenditure over commercial offerings. The www.diyaudio.com group *could* be helpful (note the use of asterisks...).


Justin

[bblackwood]

thermionic wrote on Fri, 18 August 2006 07:30

A pure Class A amp is an environmental tragedy, and I can't think of any amp that has more than around 30 watts of Pure Class A in the current marketplace (a typical 30 watts Class A amp will likely yield 300+ in Class A/B).

The Pass Labs X250 does about 75 watts class A before rolling over into A/B. It's definitely not an efficient amp, but it sure sounds good! The old Aragon Palladiums did about 125 watts class A, and you could warm a nice sized home with them...

The environmental issue regarding class A power amps is worse than just the constant draw of 500 watts - it's the fact that that power is dissipated as heat most of the time, increasing your AC run time. The actual power wasted is far greater than just idle power draw...

But again, it sure sounds good!

[JGreenslade]

I fitted bias switches on my power amps and performed blind tests with musicians. Although it was blind, it wasn't forensic, but each time I upped the bias, the musicians came out with the Class A cliches: "it's more silky, bass has more punch" etc.

Brad, are you sure the Pass is constantly biased for 75 watts Class A? I thought they were around 30 watts, and Nelson implemented a clever biasing system along the Krell lines? (I may well be wrong).

I could never change my Class A/B amps, so I try and keep my conscience clean by being efficient elsewhere and recycling etc (my dear old 18Mpg Lancia hasn't left the garage for a while now...)

Justin

edit: According to this review, the Pass X250 is good for around 25 watts before going A/B:

Quote:

All of this comes at a high price, but Pass has never been anything but a high performance manufacturer. The power supply is the most expensive part of an amplifier, and the power supply in the X250 is massive, having a 1.2 kVA toroidal transformer, and twenty 10,000 Audio is a vocational affliction "there is no "homeopathic" effect in bits and bytes." - HansP bblackwood Hero Member Offline Posts: 7036 Re: Anyone have experience with Class D amps? thermionic wrote on Fri, 18 August 2006 07:56 Brad, are you sure the Pass is constantly biased for 75 watts Class A? I thought they were around 30 watts, and Nelson implemented a clever biasing system along the Krell lines? (I may well be wrong). IIRC, that's what Nelson told me when I purchased it. But I have been wrong before... Brad Blackwood euphonic masters dcollins Hero Member Offline Posts: 2815 Re: Anyone have experience with Class D amps? bblackwood wrote on Fri, 18 August 2006 07:03 thermionic wrote on Fri, 18 August 2006 07:56 Brad, are you sure the Pass is constantly biased for 75 watts Class A? I thought they were around 30 watts, and Nelson implemented a clever biasing system along the Krell lines? (I may well be wrong). IIRC, that's what Nelson told me when I purchased it. But I have been wrong before... Your amp doesn't have "sliding bias," and I think the class A range is more like 100W. DC Dave Collins Mastering Pulse Techniques LLC Viitalahde Hero Member Offline Posts: 1069 Re: Anyone have experience with Class D amps? zenmastering wrote on Thu, 17 August 2006 22:38 Jaakko, the Hypex modules are easily available in small quantities, but I haven't found a similar source for the ICE Power modules yet. (Nor have I looked all that hard.) Yeah, I have a good Finnish source for the Hypex modules too. I'll need to check those ICE modules also, maybe they have a distributor somewhere. I am pretty convinced I'll be building my amps from these modules, most likely UcD. I get a feeling you can't really go wrong with these and anything above that is really just a taste thing. thermionic wrote on Fri, 18 August 2006 13:30 I wonder if you're confusing Class A/B amps with Pure Class A here? I don't think so, but maybe I've been reading too much audiophile bullshit lately. I quess the "first Watt is the best" comes from the high efficiency speaker circles. Good input here, people. Jaakko Viitalähde Virtalähde Mastering, Kuhmoinen/Finland http://www.virtalahde.com    http://www.facebook.com/pages/Helsinki-Finland/Virtalahde-Ma stering/278311633180 JGreenslade Hero Member Offline Posts: 824 Re: Anyone have experience with Class D amps? According to most of the Dealer Adverts, the X250 has 75 watts pure class A, so it looks as if Brad may have been right. I should dig out my books and do the math really, not that a Pass design will conform to conventional methodology... The only accurate way to find out (you can’t believe everything hi-fi reviewers / dealers tell you…) will be to hook it to a dummy load, driven by an oscillator with an ammeter across a power rail, noting at which point the power demand becomes dynamic. I guess Brad could try out the above procedure...or, he could just enjoy his amp... Jaakko – I’m struggling to figure out a physical justification for the “first watt’s the best” ethic. The only plausible explanation can be for a class A/B amp, where the amp runs into cross-over distortion abruptly after exceeding its biased region – what other explanation can there be? Issues away from biasing such as poor PSU design? Anyone who’s experimented with bias whilst the amp is connected to a distortion analyser will know that – sometimes – only a few ma extra bias can be needed to move the changeover point away from a particularly nasty switching region. Designing any class A/B amp is a juggling act where you want to find the best “compromise”, i.e. biasing away from the worst regions of switching distortion, but without the amp enticing your dog to curl around it instead of the hearth. Justin Audio is a vocational affliction "there is no "homeopathic" effect in bits and bytes." - HansP vile_ator Newbie Offline Posts: 3 Re: Anyone have experience with Class D amps? Ive been using a Spectron Musician II into into my Dunlavy Alethas for about 4 years.  Love it.  Huge power and headroom.  Never heard distortion from the monitoring chain ever.  Response is incredibly smooth with no fatigue at all.  Many hi-fi amps give you a bit of extra presence to make mixes exciting and the Spectron does not do that.  Flat, flat.  John Dunlavy recommended it. Colin Davis Print Pages: 1 [2]  All   Go Up « previous next » R/E/P Community > R/E/P > R/E/P Archives > Brad Blackwood > Anyone have experience with Class D amps?   SMF 2.0.19 | SMF © 2021, Simple Machines | Terms and Policies XHTML RSS WAP2 Site Hosted By Ashdown Technologies, Inc. Page created in 0.105 seconds with 19 queries.

[bblackwood]

thermionic wrote on Fri, 18 August 2006 07:56

Brad, are you sure the Pass is constantly biased for 75 watts Class A? I thought they were around 30 watts, and Nelson implemented a clever biasing system along the Krell lines? (I may well be wrong).

IIRC, that's what Nelson told me when I purchased it.

But I have been wrong before...

[dcollins]

bblackwood wrote on Fri, 18 August 2006 07:03

thermionic wrote on Fri, 18 August 2006 07:56 Brad, are you sure the Pass is constantly biased for 75 watts Class A? I thought they were around 30 watts, and Nelson implemented a clever biasing system along the Krell lines? (I may well be wrong). IIRC, that's what Nelson told me when I purchased it. But I have been wrong before...

Your amp doesn't have "sliding bias," and I think the class A range is more like 100W.


DC

[Viitalahde]

zenmastering wrote on Thu, 17 August 2006 22:38

Jaakko, the Hypex modules are easily available in small quantities, but I haven't found a similar source for the ICE Power modules yet. (Nor have I looked all that hard.)

Yeah, I have a good Finnish source for the Hypex modules too. I'll need to check those ICE modules also, maybe they have a distributor somewhere.

I am pretty convinced I'll be building my amps from these modules, most likely UcD. I get a feeling you can't really go wrong with these and anything above that is really just a taste thing.

thermionic wrote on Fri, 18 August 2006 13:30

I wonder if you're confusing Class A/B amps with Pure Class A here?

I don't think so, but maybe I've been reading too much audiophile bullshit lately. I quess the "first Watt is the best" comes from the high efficiency speaker circles.

Good input here, people.

[JGreenslade]

According to most of the Dealer Adverts, the X250 has 75 watts pure class A, so it looks as if Brad may have been right. I should dig out my books and do the math really, not that a Pass design will conform to conventional methodology...

The only accurate way to find out (you can’t believe everything hi-fi reviewers / dealers tell you…) will be to hook it to a dummy load, driven by an oscillator with an ammeter across a power rail, noting at which point the power demand becomes dynamic.

I guess Brad could try out the above procedure...or, he could just enjoy his amp...

Jaakko – I’m struggling to figure out a physical justification for the “first watt’s the best” ethic. The only plausible explanation can be for a class A/B amp, where the amp runs into cross-over distortion abruptly after exceeding its biased region – what other explanation can there be? Issues away from biasing such as poor PSU design?

Anyone who’s experimented with bias whilst the amp is connected to a distortion analyser will know that – sometimes – only a few ma extra bias can be needed to move the changeover point away from a particularly nasty switching region. Designing any class A/B amp is a juggling act where you want to find the best “compromise”, i.e. biasing away from the worst regions of switching distortion, but without the amp enticing your dog to curl around it instead of the hearth.


Justin

[vile_ator]

Ive been using a Spectron Musician II into into my Dunlavy Alethas for about 4 years.  Love it.  Huge power and headroom.  Never heard distortion from the monitoring chain ever.  Response is incredibly smooth with no fatigue at all.  Many hi-fi amps give you a bit of extra presence to make mixes exciting and the Spectron does not do that.  Flat, flat.  John Dunlavy recommended it.

Colin Davis