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What's my boggle with phono preamps?

wyn palmer said:
The Pyxi is not a "Lipshitz style" implementation (...)
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My post wasn't intended to imply that, anyway. But I'd assume, that you already were aware of that - so that your reply probably was merely intended for clarification, just in case someone wouldn't yet know, I'd guess.

And to make that clear: My post also wasn't intended to imply, that I'd deem using opamps a bad thing. And it also wasn't intended to imply, that I'd deem a decently implemented "Lipshitz style" phono stage such a bad thing.

Greetings from Munich!

Manfred / lini
 
Mr Boochie said:
What is "Lipshitz style" implementation in phono pre-amps?
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That would be "your usual" single-stage, (dual-)opamp-based implementation, with the RIAA (re-)equalisation being done in the feedback loop - as found in a very large number of integrated amps and receivers, but also in quite a lot of separate phono stages. See for example there: https://www.hifi-archiv.info/Dual/cv450s/450-04.jpg

Greetings from Munich!

Manfred / lini
 
lini said:
My post wasn't intended to imply that, anyway. But I'd assume, that you already were aware of that - so that your reply probably was merely intended for clarification, just in case someone wouldn't yet know, I'd guess.

And to make that clear: My post also wasn't intended to imply, that I'd deem using opamps a bad thing. And it also wasn't intended to imply, that I'd deem a decently implemented "Lipshitz style" phono stage such a bad thing.

Greetings from Munich!

Manfred / lini
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Actually, I do believe that a "decently implemented Lipshitz style" design is often a bad thing as the definition of "decently" is open to considerable interpretation. However, that's neither here nor there.
I also did not imply that you considered opamps necessarily a bad thing, although many do (The designer of the Darlington Labs units, for one, although their ranks are legion).
This was, as you stated, purely for clarification.
Indeed, I would assume that many do not know as the details of implementation is something that many care not a whit about, and rightly so, although the use of "passive RIAA equalization" seems to be a point of pride for many designs, and many audiophiles have an explicit bias against certain design approaches due to many years of, what, propaganda? (Too strong a word I know).
 
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lini said:
That would be "your usual" single-stage, (dual-)opamp-based implementation, with the RIAA (re-)equalisation being done in the feedback loop - as found in a very large number of integrated amps and receivers, but also in quite a lot of separate phono stages. See for example there: https://www.hifi-archiv.info/Dual/cv450s/450-04.jpg

Greetings from Munich!

Manfred / lini
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Many non opamp based phono stages, either discrete semiconductor or tube, use essentially the same "topology". The feedback network can be implemented in more than one way, but the result is topologically identical.
 
wyn palmer said:
Many non opamp based phono stages, either discrete semiconductor or tube, use essentially the same "topology". (...)
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Sure, but that would already be different from what I'd call "your usual Lipshitz style" implementation - just like the variants, that use an additional discrete transistor mirror in front (be that just for MC or also for MM...).

Greetings from Munich!

Manfred / lini
 
lini said:
Often enough not even that, unless one would already count minor differences (in passive component values, board layouts as well as opamp and operation voltage choices...) as doing it differently. Which is foremost supposed to refer to the large number of more or less bog standard "Lipshitz style" implementations, both integrated and separate.

Greetings from Munich!

Manfred / lini
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That's kind of what I was referring to. A lot of inexpensive phono preamps sound very similar, because they're using simple, proven topologies, and offer very similar specs, as well. I think the latter has more to do with the power supplies than any real circuit designs. RIAA equalization is a known quantity, that part is easy. I've used discrete designs, and I've used op-amp designs. The poorer ones I've used still sound decent, but they don't tend to keep you listening. Good ones sound good, regardless of the architecture. In most cases, I prefer a simpler design, with fewer features. It only has to do one thing well.....
 
justjed2 said:
That's kind of what I was referring to. A lot of inexpensive phono preamps sound very similar, because they're using simple, proven topologies, and offer very similar specs, as well. I think the latter has more to do with the power supplies than any real circuit designs. RIAA equalization is a known quantity, that part is easy. I've used discrete designs, and I've used op-amp designs. The poorer ones I've used still sound decent, but they don't tend to keep you listening. Good ones sound good, regardless of the architecture. In most cases, I prefer a simpler design, with fewer features. It only has to do one thing well.....
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The Pyxi is inexpensive and has stellar specs in an industry where specs, if present at all, are usually merely suggestions, and that is a strong function of the "architecture" as you define it.
People criticize it for lacking multiple gain settings (beyond the two), for not having a "mono" switch, or balance control, or a "rumble filter" etc. etc.
It was designed explicitly to satisfy what you claim is your preference.
Accurate RIAA post-equalization- at least accurate enough to satisfy psychoacoustic limits- is not as easy as you state, which is why very, very, few units actually have production limits that meet psychoacoustic goals for neutrality. The Pyxi does this without component matching being required. It uses automated assembly, and every single unit meets spec...
 
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I've worked in electronics for more than 40 years, working my way up from stuffing boards to being a DOD/aerospace grade QC specialist with 3 IPC instructor's ratings. What I 'claim' is my preference is based on a decent working knowledge of electronics, along with personal preferences based on my own experiences.

I seriously considered the Pyxi. Very seriously. And, for all the reasons you've mentioned. I've no doubt that it's as good as everyone says. I simply chose a different product, don't take it as a slight. I'm kind of picky. That I chose to consider the Pyxi at all, and that it was one of two contenders, could be considered a compliment!
 
justjed2 said:
I've worked in electronics for more than 40 years, working my way up from stuffing boards to being a DOD/aerospace grade QC specialist with 3 IPC instructor's ratings. What I 'claim' is my preference is based on a decent working knowledge of electronics, along with personal preferences based on my own experiences.

I seriously considered the Pyxi. Very seriously. And, for all the reasons you've mentioned. I've no doubt that it's as good as everyone says. I simply chose a different product, don't take it as a slight. I'm kind of picky. That I chose to consider the Pyxi at all, and that it was one of two contenders, could be considered a compliment!
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I don't take it as a slight. Why should I? This is merely an exchange of information as far as I'm concerned.
I really don't care whether you buy it or not. I do care how you react to it if you do buy it.
Somehow you seem to be reading more into my use of the word "claim" than I intended.
Hey, I'm a Brit. I still write the English language in a somewhat more formal way than many Americans.
Definition of claim in the sense that I used it:
"A claim is when you express your right to something that belongs to you, like your medical records or the deed to your home. When you make a claim or claim something, you're demanding it or saying it’s true".
 
It's all good. I tend to write in generalities, except for when a specific is needed, thus why I didn't mention any particular products.

People these days tend to be somewhat defensive, at least on this side of the pond, and it would appear that I am guilty of this,
as well. Carry on......
 
@wyn palmer - Mr. Palmer, do you have involvement in the design of the other phono stage that Sota mentions on their site, the “Acrux”? If so, can you talk about or tell us how it differs from the Pyxi?

Duane
 
MisterDK said:
@wyn palmer - Mr. Palmer, do you have involvement in the design of the other phono stage that Sota mentions on their site, the “Acrux”? If so, can you talk about or tell us how it differs from the Pyxi?

Duane
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Yes. There were two prototypes built, I believe. I have one at home- and that's what I use as my phono stage.
The unit has MC and MM inputs- two separate channels, optimized for each kind of cartridge. The noise is c.3dB better for MC than the Pyxi and the MM is c. 10-12dB better for real MM cartridges than the Pyxi. There is a "warp" filter. It's a second order filter that eliminates stereo (vertically modulated) content below 130Hz and has >31dB of channel separation for 1kHz and above. Laterally modulated content is essentially unaffected. There is a stepped gain stage of 0-10dB by 2dB steps, and the output is balanced or SE with a 6dB difference in gain. The balanced outputs are group delay matched and stable/well behaved into any loads.
The power supply is external and regulated then routed via an umbilical to the main unit where each channel has its own filtering/regulation. The hum level is even lower than the Pyxi.
There are more cap/R load choices using the same DIP switches as the Pyxi.
The MC gain is 64dB SE, 70dB balanced, with the gain set at 0dB. The MM gain is presently at 44dB, but that will likely change.
The pseudo instrumentation input configuration that works with actual cartridges so well with the Pyxi but so poorly in ASRs test rig, will continue to be used- no balanced inputs.
The distortion is a tad better than the Pyxi, especially in the MM mode, and the RIAA compliance is within 100mdB p-p 20Hz-20kHz- guaranteed by design but also factory tested.
The signal sockets are high grade types.
SoTa may eventually bring it to market- at least that was the plan. If so, some changes will likely occur to improve distortion further, based on learning from the Pyxi, to change the cosmetics and possibly incorporate the DC supply fully into the box, possibly with an external wall wart.
 
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I leave both the MP-7 and the Pyxi on 24/7 and I could swear they sound better today than they did yesterday. I gotta talk Sota into doing a silver front panel for the Pyxi:)

Mike
 
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