And you say there is no settling time at all other than if you changed something, or do you listen for settling time if nothing has changed?
In that case where I bought the wrong wire and not realizing it until I had removed the wire that was to be replaced then put the same one I took off back on......still noticed this settling once turned back on (although not as pronounced as if I had actually changed something...it was still noticeable)
Is there a static build up or a capacitive charge that speaker wires hold that might get upset for a bit?
Not really. More likely you amp needs to warm up or something else is going on. Maybe you listen more intently right at turn on if you know you have changed something?
Well that was kinda the point......I hadn’t changed anything.(besides taking wires off then same ones back on)
It may have took 10 minutes between warmed up on/off/back on again.
I can’t see it cooling off that much in 10 min......but, yes it does take a good 30-45 minutes to get up to speed from dead cold.
It may have took 10 minutes between warmed up on/off/back on again.
I can’t see it cooling off that much in 10 min......but, yes it does take a good 30-45 minutes to get up to speed from dead cold.
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Not that it matters (or that I disagree), but the AHB2 is Class AB with some kind of Class H rail tracking scheme.
Cool, some Lundahl SUT's and 8-legs. We had a term at work SOP salary/performance.
Well that seems like a plausible explanation for the ‘settling’ .... and now that it’s mentioned the sound during the settling period is much the same as that of not being warmed up sufficiently.
But there’s still the differences in other wire types after that fact
But it has so many fancy looking caps. Big array of black electrolytics, big red Wima film caps, presumably audiophile axial caps. Everyone knows you can't have good sound without at least 0.5F of electrolytics to fill the empty space in your pre-amp.
It uses FF error correction (Hawksford). There is no rail switching in ABH2 AFAIK.
"The AHB2 makes use of THX Corporation's Achromatic Audio Amplifier (AAA) technology, in which a low-power feed-forward amplifier drives a low-bias class-AB output section, the latter energized by a system of class-H power-supply rails that deliver power in response to demand - resulting in an extremely efficient amplifier capable of robust power output."
AHB2 Award - "Class A Recommended Component", Stereophile - Benchmark Media Systems
So went back to what I usually use in that position; a big, over rated Dale RN65.
Midrange came back
Two important things to notice (1) It's a feedback path (2) Resistance is very high. I will use no less than a Dale resistor.
Ok, thanks Robert.It is a circuit like the one attached except ground the loose end of the 10k resistor and signal input is put into the non-inverting node. I have different resistor values.
The resistor I had to change is the one labled 2M2 (221k in my circuit though). My version has 40db of gain so everything is magnified. At that kind of gain the 2M2 position plays a much bigger part in the quality of the high frequencies than one would think. This is in spite the corner frequency being at about 200hz!
I had initially used a pretty nice thin film SMD resistor and that is what sounded bright and scooped. Could have been useful for a mic preamp or some such but for LP playback it wasn't my cup of tea.
So went back to what I usually use in that position; a big, over rated Dale RN65.
Midrange came back
Anybody have theories of the reasons for these observations ?.
Two physically different sizes, no doubt with differing noise values and temperature dependence, perhaps different chemistries ?.
Dan.
If there is thin midrange and over emphasized highs, that sounds like a distortion symptom to me. So, maybe check things like:
Different power ratings?
What is the voltage across the part? Maybe try more small value parts in series to see if that makes a difference.
Board cleaned properly after soldering?
If it sounds different, keep looking to find a normal engineering explanation, that is the main thing.
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How about a headphone driver that draws 100W quiescent? The efficiency card plays well into the 7 channels in a small TV chassis.
Who doesn't want a 50 lb space heater for their headphones?
I don't know how efficient the THX-AAA schemes are (there appear to be several variants), but I suspect they would have trouble beating the newer Class D chip amps out there. Wonder if they will or have gotten any design wins in the high end AV receiver space.
Mark beat me to it, but I'm pretty sure there is, since their own product spec page says:
"The feed-forward error correction also allows the use of class-H tracking power supply rails without the usual distortion-performance penalty. These tracking rails significantly improve the overall efficiency of the amplifier while the error correction keeps distortion nearly nonexistent. The AHB2 rivals the efficiency of class-D amplifiers while exceeding the sonic performance of power-hungry class-A designs. Green never sounded so good!"
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That is the basic fight, get conventional amplifier technology to beat the class D onslaught. This falls under my first rule of business, patching old tech to beat new tech is a guaranteed losing proposition. The silly numbers game, mine is -130dB and yours is -120dB will fade away.
There will always be a place for Son of Zen just there on the margin burning away.
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AHB2 power amp has very low distortion even at 100mw of power due to the class-A feedforward. I doubt high wattage class-D designs can do that at this point. It matters to me because I like to be able to operate the amp over a wide range of volume levels.
For the bulk of the market class-D seems likely the way to go. Probably be awhile before the best of what Bruno can do today filters down to commodity products however.
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