What is that impression based on?
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Review and Measurements of Purifi 1ET400A Amplifier
- Thread starter amirm
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What is that impression based on?
maty
Major Contributor
That some of us like a certain type of sound does not imply that we should despise who appreciates a different one. I limit myself to post the information and there each one how he spends his money.
For me, the ideal would be a switch that allows switching between two types of harmonic profiles. Better yet, a VSTplugin. Having two systems complicates and makes more expensive ALL.
For me, the ideal would be a switch that allows switching between two types of harmonic profiles. Better yet, a VSTplugin. Having two systems complicates and makes more expensive ALL.
maty
Major Contributor
English: https://www.audiophonics.fr/en/powe...ass-d-stereo-purifi-2x400w-4-ohm-p-14393.html
Rotated, clarified and optimized
Audiophonics Interface Card
[ Both modules are driven in opposite phase, to cancel out the «Power-Supply Pumping» effect. This allows greater stability in the power supply by alternately distributing current draws on each rail, thus increasing its overall capacities.
We opted for a regulation with two voltage levels in order to optimize the power supply to the PDOs and the auxiliary voltage supplied to the modules. This allows the OPAs to be powered with a high voltage (18V) for better overall performance, and allows them in turn to provide the voltage needed to reach the amplifier's maximum output level. While still maintaining the auxiliary voltage required by the modules.
Each channel uses its own Analog Devices OP275 AOP. They are based on a hybrid Bipolar / JFET technology. Bringing precision and musicality. They are mounted on a socket allowing their possible replacement.
To suit all uses we opted for 3 gain settings, adjustable by jumper on the interface card:
Rotated, clarified and optimized
Audiophonics Interface Card
[ Both modules are driven in opposite phase, to cancel out the «Power-Supply Pumping» effect. This allows greater stability in the power supply by alternately distributing current draws on each rail, thus increasing its overall capacities.
We opted for a regulation with two voltage levels in order to optimize the power supply to the PDOs and the auxiliary voltage supplied to the modules. This allows the OPAs to be powered with a high voltage (18V) for better overall performance, and allows them in turn to provide the voltage needed to reach the amplifier's maximum output level. While still maintaining the auxiliary voltage required by the modules.
Each channel uses its own Analog Devices OP275 AOP. They are based on a hybrid Bipolar / JFET technology. Bringing precision and musicality. They are mounted on a socket allowing their possible replacement.
To suit all uses we opted for 3 gain settings, adjustable by jumper on the interface card:
- Gain of + 9.5dB, for a total of 22.3dB (default) Maximum power reached with a signal of ~ 3.2V RMS
- Gain of + 15.5dB, for a total of 28.3dB Maximum power reached with a signal of ~ 1.6V RMS
- Bypass: in this case the signal passes directly from the inputs to the modules, allowing the lowest possible gain of 12.8dB. This mode can be interesting when using a powerful preamplifier, capable of driving a load of 2 to 4kOhm and reaching a voltage of ~ 10V RMS ]
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Just reports and impressions I have read, posted by others who have built or bought systems using them.
Also, when you consider the small fraction of a high voltage triode's curves you actually use for small signal amplification. and the inherent linearity because it is only a small fraction, and the headroom, because you just can't ever drive to the rails with a small signal, then when you compare that to the poorer performance and sound of those same tubes working on starved plate voltages, as they do in these many tube "buffer" devices being peddled, that only run from HT well under 100V. sometimes as low as 12 or 24V. Even allowing the Nutube dimensions and design try to allow good performance on low voltages, I still have a doubt that they will sound as good.
I really must build one myself one day soon. I might be pleasantly surprised (or not).
I really must build one myself one day soon. I might be pleasantly surprised (or not).
Indeed. You won't know until you try.
D
Deleted member 65
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An examination of the device characteristics. The NuTube is clearly made to cause distortion, and has insufficient gain and transconductance to correct this. And, of course, it is indeed microphonic.
A properly designed 12AX7 or 12AT7 circuit will have vastly lower distortion, lower microphonics, and higher bandwidth.
The NuTube is also extremely microphonic even more so than regular tubes probably due to less mass. Measurements using dummy load maybe isn't good enough due to that property. The sound is going in there.
This is affordable.
That depends on one's design goals and esthetic constraints. Personally, I enjoy getting high performance out of anachronistic technologies.
Wow! I want one. Glad there's no boutique opamps. Interesting how their buffer performs vs EVAL1 board?
It as a resistance of 100 ohms in series
Fair enough, "subjectivity" was a poor choice of word.
I get why ASR exists! I feel good too when I see a spinorama that looks like a monkey tried surgery with a tail-held jigsaw, for a bookshelf the industry wants me to believe sounds "clear and clean" given "six hours of transformative use".
That said, it's strange to see new people coming here and this conversation happening:
Noob: Hi, I'm new, I like measurements but I'm observing phenomenon <x> in product <y>, which doesn't seem to line up with conclusions drawn. Could anything account for this?
Forumite: Yes, what accounts for it is that your observation is useless. Go learn what a double-blind test is.
The conversation now usually hits a fork, between:Noob, left path: Well, <expletive>, I'm <credentials>, I speak math! All I'm saying is that <y> sounds like dying cats, not violins!
Noob, right path: Well, <expletive>, and <lots of nonsense>, and your double-blind tests are a sham! You're a cult!
I get why the right-path folks are shunned/banned. It's the replies to the left-pathians that surprise me. I'd expect...Forumite: That's interesting, math-claiming noob. Do you have any working theories for what could account for this difference? Is there any way you can quantify phenomenon <x>, perhaps so we can reproduce it in an experience we have confidence in? Then we could explore, because science!
...instead, I usually see:Forumite: Sighted perception! Auditory memory! Instantaneous AB comparisons! Your impressions and your entire line of inquiry are without merit, because science!
To me, the tone seems mean-spirited, and the conclusions a priori seem, well, unscientific. But I suppose you're right, the definition of "meaningful" matters for convos like these.Edit: found the DIY thread, my bad.
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Don't worry, you can swap the original opamp to your boutique DIP8 opamp later.
"One Analog Devices OP275 AOP per channel is used, they are based on a hybrid Bipolar / JFET technology. bringing precision and musicality. They are mounted on a socket allowing their replacement if necessary."
The price for this Audiophonics is very impressive!
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