[eric343]

Again, I think that "swing" as it is referred to in reviews and "slew rate"/"bandwidth" as referred to in datasheets are two different things.

 

[kelly]

Quote:

Originally posted by eric343 Again, I think that "swing" as it is referred to in reviews and "slew rate"/"bandwidth" as referred to in datasheets are two different things.

Eric
So what then do you think other people mean when they say "swing"?

 

[tangent]

Quote:

I think it's because you're reading reviews, not datasheets

You can get fooled by reading datasheets, too. You quoted two 350 nS settling time numbers there, but they aren't equivalent: one is for a 2V step, and the other for a 4V step. Also, the AD823 test was done with the chip in inverting configuration, which gives a faster slew rate than noninverting configuration. You can't compare these numbers without adding fudge factors.

Quote:

The Max, to me, ranks well below a handful of other amplifiers in terms of texture and ambient detail. Don't get me wrong, the Max has other traits that make it worthy but that's just not one of them in my experience. So then, where is the inconsistency? Does the Max really not have "good swing"/"high slew rate" compared to other amps?

The Max uses the OPA627 op-amp, which has a 55 V/us with settling time after a 10V step to 0.01% in 550 ns. The AD843, which I think sounds better, has a 250 V/us slew rate with settling from a 10V step to 0.01% in 135 ns.

 

[kelly]

tangent
So are you saying that the roughly 4x faster slew rate of the AD843 is why the META42 would yield better texture and ambient detail than the Headroom Max?

That aspect owes so much to just the opamp?

 

[tangent]

You'll have to make that judgement on your own, kelly, when you get the amp back. Sorry, I'm just not in a position to tell you more. I haven't even listened to a Max, so I'm really out on a limb here. (I did listen indirectly to some MOH's at the Headroom road show, but I was listening for differences in headphones, not amps -- as you can imagine, I'm not in the market for a Headroom amp.

)

Quote:

That aspect owes so much to just the opamp?

The op-amp is the amplifier. Everything else is support circuitry.

 

[kelly]

tangent
Your amp was more of a "f'rinstance" cos I figured that's what you knew. It's not the only amp I feel this way about but almost all of the amps I can think of that do have better texture and ambience than the Max run in Class A. Even the McCoramck does and it uses opamps that Steve McCoramck "upgrades to opa627" if you purchase his upgrades. (Not sure which opamp is in there now.)

 

[Www]

Quote:

No, accurate is when you put in 20-20000 Hz in, you get 20-20000 Hz out, with no rolloff or humps or dips. Transparency is a different thing entirely. It has more to do with having a fast slew rate than anything else. Slew rate is a measure of how fast an amplifier can "swing" from 0V to a full signal level. The faster it swings, the more accurate

Ok then maybe transparency is a 'kind' of accuracy ?

Ok then i'll say "accuracy" first, then transparency.
Power, less important.

Under $200.

 

[Www]

Does a crossfeed circuit affect the quality of the output ?

 

[Www]

Quote:

By the way, some people have reportedly gotten ultra-reference transparency using DSL line drivers - opamps with slew rates in excess of 470V/uS, bandwidth of 350MHz (gain = 10), and settling time of 145nS.

Any amps with this on board ?

Can u put one in a meta42 ?

Is it practical ?

Is there an audible difference ?

 

[Www]

Anyone ?

 

[tangent]

Quote:

Under $200.

You should ask individual builders when it comes to pricing. That's not a matter for the non-profit sections of this site. Hint: there's a for-profit section of the site, and there's a builder advertising his services there.

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Does a crossfeed circuit affect the quality of the output ?

Of course -- anything in the signal path degrades the sound. Of course we strive to make the impact of the crossfeed circuit as small as is practical, but we are not 100% successful.

Quote:

Any amps with [high-spec op-amps] on board?

Personally I avoid such chips. They tend to be very difficult to use. The fastest chip I've ever used and enjoyed is 80 MHz. I've also used a 100 MHz chip once, but it was a pain to use. This isn't to say that all 100 MHz chips are a pain -- I'm only talking about that one chip in particular. It's a moot point anyway: I generally only use 8-34 MHz chips. These can be quite accurate. I find little advantage in using super-exotic chips.

 

[Possum]

Quote:

I find little advantage in using super-exotic chips.

You never know until you try. I believe Tomo built his DSL chip-based amp on an evaluation board that cost $50, then add in power supply and typical input/output components, etc.

http://headwize.powerpill.org/ubb/sh...me=0&srch=dsl;
http://headwize.powerpill.org/ubb/sh...&srch=ths4022;
http://headwize.powerpill.org/ubb/sh...&srch=ths4022;
http://headwize.powerpill.org/ubb/sh...&srch=ths4022;

There's more info, just search for THS4022 within the DIY forums of HeadWize.