Phantom Power Capacitors

[john12ax7]

Italian cuisine

Ital is its own thing, it's not Italian

 

[abbey road d enfer]

Really, I get the opposite feeling. Maybe our relative definitions of BS are at odds,? Same for braggarts?

Probably. If I'm guilty of BS or bragging, give me an example. I'm ready to have my nose rubbed.

As it seems that in your mind a schematic is required, have one.

This is a basic Cohen. Is it your definitive answer?

This circuit from a THAT presentation is suitable to be DC coupled to the input, including phantom power, with a few very minor adjustments and the addition of relevant servo's. How to should be blindingly obvious.

It's these "few very minor adjustments" that I would like to see. They're so blindingly obvious that I don't see them.

To get rid of these polarised coupling capacitors, their distortion, the required protection circuitry etc., the associated board space, cost and whatsnots is trivial.
It can be done using minor adjustments of existing circuitry decades old with minimum added complications.

We all know the devil is in the details. These minor adjustments usually turn out to be major PITA's.

It could also easily made into an IC including power supplies from a single 5V rail.

In essence, the concept is a diff amp with a CM voltage range of about 55-60V. I believe it requires at least one rail of similar voltage. Maybe I'm wrong. Educate me.

 

[k brown]

To dumb this waaay down to my level, I guess I just see that virtually all mics have DC block caps on their outputs; is putting the signal through just a single additional cap at the input of the preamp really going to be audible?

i.e.: With all the caps in a recording chain from mic internal to A/D converter (not to mention the post-production chain), is eliminating just the DC phantom block cap at the input of a pre going to reduce distortion audibly?

 

[abbey road d enfer]

In my view you are just not thinking things through, because you don't want to solve the problem posited, which would be trivial.

Instead you want to assert that:

This just shows you don't understand. I don't want to assert anything, I'm just asking down-to-earth questions.

I believe we all recognize the issue with capacitors. However, this issue must be put in perspective with its real practical consequences, and thus an evaluation of the benefit-to-cost ratio must be made. I believe you are completely underestimating the difficulties in producing a practical, cost-effective working product.

Instead of lecturing us about our lack of determination, why don't you produce a working prototype, with real-life measurements?
When it works, endeavour to convince Yamaha, Digico, Midas, et al, to use your circuit.

BTW, there is enoug evidence that biasing some capacitors influence distortion; you can't just dismiss it for the reason it generated an "old wife's tale". This is worth analyzing. I agree that previous attemps at this have not been thorough enough and have resulted in precipitated conclusions.
More of a reason to dig deeper.

 

[CJ]

I wish people who owned live music venues were as picky as you guys.

 

[MicUlli]

0xDEADBEEF

 

[JohnRoberts]

Abbey is the kinder, gentler mod around here....

Let's all be a little kinder and gentler.

JR

 

[abbey road d enfer]

Hmmm, how many practical, cost-effective working products did you design and introduce to the market? Me, probably easily over 50, not counting minor variations.

I see. Now is time for dick contests.

Well, do you know NIH syndrome?

Very well.

"Influence" yes.

But with the exception of one specific product (Black Gate Audiophile Capacitors - long discontinued) the influence is negative.



Oh no, it IS an old wives tale, because it has been disproven for decades.

You have just agreed that polarisation influences distortion. Read again. I've never advocated the fact that polarisation improved distortion on a general basis. I just said it changes it, and as such is worth investigating.

I agree no such thing. It is really well documented.

I see flaws in scientifid method in all the tests I've seen, including Bateman's.

These were fairly large tests to see if the extra cost for "BS Snakeoil Parts" can actually be justified in production or if it's just BS. Conclusion, not BS and in mass production definitly worth it.

I'm not categorical. Some are worth it and some are BS. that's why investigating is necessary.

 

[sahib]

Anyway, phantom powered Microphones are last Millennium, nobody is really interested in much to do with it.

Thor, this is an unqualified statement and you are wrong.

 

[sahib]

Word "nobody" Thor, word "nobody".

 

[Mr. Moscode]

Totally transparent pro audio gear is a waste of time as nothing really sounds as good in person as it can be made to sound after recording with hot & fat gear, punchy or smooth as needed,....with the exception of some instruments used to make classical music and the like especially when there is a desire to hear how good that instrument is...a multi-million dollar violin for example....but then the loudspeakers' coloration will swamp out a lot of micpre and recording chain differences.

So fake sound is better?

There is a winning sound but people not into winning often fail to notice.

Sounds like you're a grad of Trump University.

 

[abbey road d enfer]

Thor, some of your posts are pure nonsense.
As I said earlier; read again. You misunderstand many things and get confrontational.
I'm out. Wasting my time with someone who ALWAYS want to have the last word is insane.

 

[JohnRoberts]

This thread jumped the shark long ago, IMO.

JR

 

[k brown]

They do? Transformer's too in some cases.

In other cases they do not have DC Blocking Capacitors and Transformers on the output and use film capacitors for coupling.

View attachment 130566



Potentially yes.



Why do presume there are these capacitors?

Here a modern ADC Input:

View attachment 130567

Here a version with the PGA2500 Microphone Preamp:

View attachment 130568

Look mama! No coupling capacitors.

If it was not for those pesky phantom power blocking input capacitors, we would be "no capacitor" from Microphone to ADC.

So where do you see the "Many Capacitors"?



Depends what sort of capacitors you use and how.

If you use a pair of ~10uF FKP Capacitors they will not add distortion that is appreciable, even though even they will show increased distortion.

Now let's say 10uF FKP are a bit big and expensive, you could use Nichicon Muse ES series "Audio Grade". But they are much bigger and more expensive then generic electrolytic capacitors.

So instead you put generic polarised Capacitors (RVT from Honor). But now we have audible distortion and they still COST MORE than a wire or PCB trace.

So if we had a PGA2500 with my suggested of frontend with ADC, a Microphone based on the Schoeps design we would have literally a pair of Film Capacitors and the capsule as the sole capacitors between air pressure changes and ADC.

Thor

Perhaps I was unclear.

I meant in a typical real-world use case, there WILL be many capacitors in the entire chain between a mic capsule and an ADC (not that such a path couldn't be concieved of with few or no caps in it). And in such typical chain, would the elimination (or even just upgrade) of only one cap, really be audible?

Just think how many caps are in the signal path of the average analog mixer alone (many still use them, you know ).

 

[abbey road d enfer]

You don't need to do text explanation. I believe Thor is fluent enough in English to understand subtleties.
But he's devious enough to edit citations and put them out of context or at an extreme limit.
One never gains (note: I'm not saying "wins) at palavering with someone whose intention is to demonstrate that they are smarter, know more and have a better understanding than you.

 

[kags]

Interested in people's thoughts on what to use for phantom power blocking capacitors in the audio path. There are basically 3 options

1) Polar electrolytic
2) Bi-polar electrolytic
3) Film, if allowed by space and cost

I'm well aware of things like Cyril Bateman's articles. Looking more for any other measurements or listening tests people have done and specific cap suggestions to try.

Thought the Nicicon MUSE ES might be a good choice, but they only go up to 50V. In the Forssell pre, which sounds amazing, seems to be polar Nichicon "audio" electrolytics in parallel with film caps. (The Nichicon have been discontinued).

So, what caps do you use?

We started back here, with this question and somehow wound up discussing USB outputs from podcasting and consumer gaming products. I'm sure USB microphones outsell professional studio microphones in 2024, but the question wasn't about that.

I'm interested in the original question. At my facility, we record around 1,000 vocal sessions per year, mostly for pop/R&B/urban records, and I've yet to see an artist or producer come in with a USB microphone. I'm sure it will happen, and I'm sure it will happen soon and often. For now, Neumann, Sony, AKG, Shure, and Telefunken, get the lion share of the sessions, with Shoeps, Sennheiser, sE, and some boutique brands following behind. Artists and producers who bring in their own microphones usually bring a model that we already have several examples of, but they prefer their specific unit for sonic or superstitious reasons.

Same goes with our preamps, which are the standard Neve, API, SSL, Avalon, Chandler, Summit, Tube-Tech, Martech, and Amek. I've yet to see anyone record directly into their audio interface without going first into a traditional (XLR) preamp and then line into their interface. I'm sure at home artists use USB mics and built-in interface preamps, but given the choice, they opt for traditional gear that they trust and of which they prefer the sonics.

When repairing/restoring gear, I would love to have a greater understanding of how different blocking caps might affect a particular circuit. We can all do the testing given the time and energy, but that's not always practical or efficient, so crowdsourcing info and opinions is kind of the point of this forum, right?

I'm super interested in modern designs that don't rely on traditional paradigms. I'm excited for plugin developers to stop cloning old gear and get on with developing new ideas for dynamic controllers and tonal processors that we haven't seen 100 versions of previously. Thor seems to be on the cutting edge of amplifier design, which is awesome, but we also have to keep a foot in the everyday world around us.

This thread is exhausting!

 

[JohnRoberts]

Perhaps I was unclear.

I meant in a typical real-world use case, there WILL be many capacitors in the entire chain between a mic capsule and an ADC (not that such a path couldn't be concieved of with few or no caps in it). And in such typical chain, would the elimination (or even just upgrade) of only one cap, really be audible?

Just think how many caps are in the signal path of the average analog mixer alone (many still use them, you know ).

Yup... I recall back in the 80s listening to audiophools complain about how many switch contacts were in a given audio path.

They would lose their (little) minds if they realized how many switch contacts are in a typical console audio path. This is all about perspective.

[edit- my answer from back then remains unchanged. If you can hear a switch (or capacitor) in your audio path, it may be a dodgy part. /edit]

JR

 

[kags]

Lots of interesting stuff there - thanks!

 

[Mr. Moscode]

I see. Now is time for dick contests.

Very well.

You have just agreed that polarisation influences distortion. Read again. I've never advocated the fact that polarisation improved distortion on a general basis. I just said it changes it, and as such is worth investigating.

I see flaws in scientifid method in all the tests I've seen, including Bateman's.

I'm not categorical. Some are worth it and some are BS. that's why investigating is necessary.

Hey Abbey Road. You're a moderator on a DIY forum yet you feel the need to personally attack Thor and others, including me one time. Quite frankly if you can't keep your comments civil you don't deserve the title of moderator.

When I run into these personal attacks on any one they are neither funny or of value and quite frankly it makes me not want to participate. Every one is here because of a common interest.

If you can't keep a civil point of view walk away from the keyboard until you can.

 

[JohnRoberts]

Remind me which wildly successful 1980's british mixer maker replaced pretty much ALL mechanical switches with J-Fet's and together with some other minor changes to the old style circuitry revolutionised recording, dominated the serious market for the next decade plus and defined the "sound" of music for Gen X?

And yes, their Mixers sounded SO MUCH cleaner than the old stuff.

Thor

Sorry I can't...

If their JFET switched design sounded better than mechanical switches those were either some pretty crappy mechanical switches or there was something else wrong with their previous design.
===

Hey Abbey Road. You're a moderator on a DIY forum yet you feel the need to personally attack Thor and others, including me one time. Quite frankly if you can't keep your comments civil you don't deserve the title of moderator.

When I run into these personal attacks on any one they are neither funny or of value and quite frankly it makes me not want to participate. Every one is here because of a common interest.

If you can't keep a civil point of view walk away from the keyboard until you can.

Seriously?

JR