Class D is just Dandy!

lalitk,

Ive been using my set of 600m's for 14 months paired with a canto pre3 which I have had much longer.

I used the nc400 for 4yrs before I got the 600 and I have a red dragon s-500 that only has 100 hrs on it.

I have always been a fan of higher pwr amps even with higher efficient speakers,I started 30 yrs ago in this hobby with Khorns and a Mac 275.

I don't really know for sure and haven't seen any documentation yet that says higher pwr Class d amps don't sound as good as lower power class d amps.

Maybe someone with more knowledge and experience with class d amps only  than me could chime in.

Kenny.

I'm playing catch-up on the posts but thanks for the recommendation on the Wtred gear Scott. That STI has been on my short list as well, most likely the v1 since the used prices sre
mire in my budget. I just haven't been lucky enough to snag one on the forum yet....

Todd, thanks for the reply. Please pardon my ignorance but I'm  not sure what you mean by different input impedance. I'm still a bit of a rookie at the terms and what they mean towards the resultant sound. 

If I may throw in my thoughts on the sound quality of class D amps, I can sum it up in 3 words: I'm a fan!

@autre I won't pretend to be smarter than I am.. I don't understand why it matters either, but preamps have a characteristic output impedance and amps have a characteristic input impedance. If memory serves me right, the amp input imp should be 10x higher (or more) than the preamp output imp. Having them too close can apparently cause the system to sound off or cause an increase in noise.

Anyone with more detailed knowledge, PLEASE addend or add!

Hi Guys,

The biggest issue with input/output impedance is the change in frequency response. This is especially bad with tube pres as they usually have a high output impedance. Driving a low impedance input amp can affect the overall response and deviate from ideal. With purist tube pre's even the volume control setting can affect things because they lack additional buffer stages that would prevent this.

Good ways to see this is to look through the Stereophile archives and look at tube preamps. In the measurements section you will see the frequency response driving different simulated amps. Here is a link:

http://www.stereophile.com/category/tube-preamp-reviews

If you look at this particular preamp, youll see the FR changes a great deal when driving a 100k load vs. 600 Ohms.

http://www.stereophile.com/content/vtl-tl65-series-ii-signature-line-preamplifier-measurements#aVQTI...

High impedance inputs also tend to be noisier (I think).

Solid state preamps or op amp based preamps can easily be completely flat down to 600 Ohms.

So, wanted to make things a little more full.

One of the spec’s commonly sited is S/N (signal to noise) or related THD+n (Total Harmonic Distortion + noise). The problem with Signal to Noise is that it is often cited at full power, and not at a more reasonable amount, like 1 watt.

So, a 1000 watt amplifier can claim 10 dB more S/N than say a 100 Watt amplifier that sounds exactly as noisy. The full power S/N ratio becomes useless for comparing amps and how quiet they are. What I wish reviewers and manufacturers did more consistently is rate the S/N at 1 watt or 10 watts. Something small so we can compare what we’ll actually hear.

Distortion is also something that tends to go down as power goes up until the limit of the amp is reached. This is why these figures can be misleading. This is something stereophile does a little better, in showing graphs of THD vs. power output. Now we can at least look at charts to compare noise and distortion as more usable power outputs.

The other thing, I think that the amplifier community is having a hard time keeping it’s prices up to make boutique manufacturing possible. This makes it necessary to have big differentiation. For instance, having a 1,400 watt amplifier is cool and all, but in my living room, at my listening levels does it mean my sound is better than my 250 W amps?

I don’t really know all the answers to these questions at all. I’m just sharing where I start to scratch my head. :)

Best,

E