[noseallinit]

any design that is moving forward in using less of our resources and being energy efficient has me interest.

I read once about a lot of high end audio manufacturers getting together as a group to design audio equipment using less resources and conserving energy. anyone know anything about who they are?

how much less resources and energy does a class d amp use over a tube amp?

 

[krmathis]

* Why aren't all amps tube-amps?
* Why aren't all headphones electrostatics?
* Why aren't all cables made of virgin silver?
* ...

 

[unoab]

Quote:

Originally Posted by krmathis /img/forum/go_quote.gif * Why aren't all amps tube-amps?

...maybe because some people like an amp with low distortion, decent amounts of headroom, and an output impedance that is not in the double digits and is flat across the audible frequency spectrum...

 

[nikongod]

Quote:

Originally Posted by unoab /img/forum/go_quote.gif ...maybe because some people like an amp with low distortion, decent amounts of headroom, and an output impedance that is not in the double digits and is flat across the audible frequency spectrum...

yes, but some of us also like amps that dont produce RF too.

transformer coupled amps easily achieve low output impedances. nobody said it had to be OTL...

it is worth note that a class-d amp relies HEAVILY on the load impedance being predictable. when you start to mess around with that you loose the filter... good luck serving everything from 32 to 600 ohms on one amp.

 

[unoab]

Well my statement was meant to cover both solid state and digital amp designs, but was more so meant to poke a little fun at the tube people... so im guilty in that case

...

I'll agree that transformer coupled amps are really nice too, who can argue against the crown macrotec amps, heard you can weld with them if you so pleased..

And for the digital amps the impedance dependent part of the amp is the output filter, which again is probably the most problematic part of the design. There are alot of different implementations/topologies, some much much better than others, some actually are load independent, despite what you say, by incorporating the filter into the feedback loop of the amplifier, but they are slow coming to market (I'm singling out one company in particular here).

Overall the technology is improving very quickly.

Also I was more so referring to power amps to be used with speakers, not so much headphones, so hopefully you will rarely see impedance peaks over 32 Ohms in a speaker.
And proper circuit design and filter placement can/will remove all radiated RF that may be from the transistors switching.

 

[diff_lock2]

Quote:

Originally Posted by terrymx /img/forum/go_quote.gif i have also wondered. why aren't all cars honda, 1.6liters and does 40mp/gallon.

Wrong.

Why aren't all cars powered by the two litter 9k rpm honda engines.

Or those 1000hp 2.0L F1 engines from back then.

 

[fran]

all manufacturers making class D/T - heavens forbid!!!

Its enough for do-gooders talking about not using a valve amp because they aren't "green". If that kind of talk grabs a hold we are all in trouble. One kind of amp, one kind of sound, one kind of colour, one kind of music will be next.

Vive la difference!

Fran

 

[DrBenway]

Quote:

Originally Posted by trains are bad /img/forum/go_quote.gif What's keeping the class T amps from taking over? I've never heard anything bad.

I don't know what has happened in the meantime, but this might have something to do with it:

(From the Tripath Wikipedia article) Despite superlative performance at low cost from the Class T approach, financial difficulties have caused Tripath to file for Chapter 11 bankruptcy protection on 8 February 2007.

I've got an original T-Amp driving my PSB Stratus Minis. They are very inefficient (87db 1watt/1meter, 4 Ohms), so the T struggles when I turn up the volume. I've popped the T's circuit breaker numerous times.

I would dearly love to find an amp with the same sound sig with maybe 50 watts a side at a reasonable price. The Bel Cantos are not in my price range. When I got the T, I was sure that I would soon have a variety of mid-priced options. Not so far, unless I'm missing something.

 

[jung]

Quote:

Originally Posted by DrBenway /img/forum/go_quote.gif I've got an original T-Amp driving my PSB Stratus Minis. They are very inefficient (87db 1watt/1meter, 4 Ohms), so the T struggles when I turn up the volume. I've popped the T's circuit breaker numerous times. I would dearly love to find an amp with the same sound sig with maybe 50 watts a side at a reasonable price. The Bel Cantos are not in my price range. When I got the T, I was sure that I would soon have a variety of mid-priced options. Not so far, unless I'm missing something.

Winsome Mouse
Little Dot T100
Panasonic SA-XR55
Onkyo A-9555
http://stereo.50webs.com/

 

[nikongod]

Quote:

Originally Posted by unoab /img/forum/go_quote.gif Overall the technology is improving very quickly. And proper circuit design and filter placement can/will remove all radiated RF that may be from the transistors switching.

you cant remove ALL noise under all conditions with a passive filter.

T-amps work with speakers because the load is predictable (8 ohms) and the filter can be designed around that.

it is virtually impossible to design a filter with low output impedance that will work for a 32 and 300 ohm headphone.

 

[mencargo]

Class-T are here to stay, $50 for hi-fi amp
I just ordered a Amp4 from 41Hz! wish me luck!

 

[unoab]

Quote:

Originally Posted by nikongod /img/forum/go_quote.gif you cant remove ALL noise under all conditions with a passive filter.

Of course you cant remove ALL noise (bad choice of absolutes on my part), but how low do you need to reduce it before people realize that the cellphone in their pocket is emitting more RF than their amp?

Quote:

Originally Posted by nikongod /img/forum/go_quote.gif it is virtually impossible to design a filter with low output impedance that will work for a 32 and 300 ohm headphone.

"impossible" in this case is only relative to the determination and ingenuity of the engineer (well and the right design constraints to start out with).



mencargo, the 41Hz amps are really good kits, I have an amp6 myself that is nice (a bit underpowered though), but it was easy to put together and Jan is very helpful if you have any questions or problems at all.

 

[fran]

Don't take my earlier post as t-amp bashing either. In fact I once heard a Charlize amp from DIYparadise.com and thought it was the bee knees. Beautiful sound very refined and bass response was very good. That'd be the one I'd buy if I was to get one. Must go and do just that in fact!

Fran