U87 circuit, and HF roll-off curve

[tomas.borgstrom]

Or is it after all about the person who knows what they are doing even if you give them vocal take made on two diametrically different mics?

I'm not surprised that Tom Elmhirst managed to match the sound of the two microphones. He's one of the absolute top mixing engineers and still it seems like he had to spend a lot of time and effort to succeed. His mix of Bowie's Lazarus is one of my absolute favorites of all time. Great musicians and Visconti being the producer does help.

Or am i crazy to chase Classic 2's sound for 15 years without knowing what it was?

I can't figure out if this is a sarcasm. How come that you with your knowledge and skills can't figure it out? I've never heard Røde Classic 1 or 2 but I have the schematics of Classic 1. It's basically the circuit of AKG C24 (in mono) with their edge terminated K67 type capsule. Is the transformer produced in house? Does the body contribute in a certain way? Surprising to find a NOS GE6072 in a microphone in that price range.

 

[kingkorg]

I can't figure out if this is a sarcasm.

Not sarcasm, but i'm not best with English tenses. My vocal was recorded with a Classic 2 in 2005 when i knew little about condenser mics, and i lost contact with the engineer who made the recording. Chased info on my own recording session for years, only to find out couple years ago it was Classic 2. However i also figured out the magic of the take, and mix for that matter was about the engineer, not the mic...

Classic 2 circuit is quite unique, sadly i'm not allowed to share the schematic. Uses two halves of 6072 in paralel, plate out to bipolar, to transformer. Very interesting biasing.

 

[tomas.borgstrom]

Classic 2 circuit is quite unique, sadly i'm not allowed to share the schematic. Uses two halves of 6072 in paralel, plate out to bipolar, to transformer. Very interesting biasing.

Makes me think of the Lucas CS-1 designed by Oliver Archut. It has a "secret tube" wired in parallel. Theres a thumbnail of the schematics on the recording hacks site. But it's not possible to enlarge it so the values of some components also remain a secret. I hope that I will come across a Classic 2 so that I can reverse engineer it.

 

[abbey road d enfer]

I'm not surprised that Tom Elmhirst managed to match the sound of the two microphones

Neither am I. I can do that in a matter of minutes with the help of Samplitude's FFT Filter Analyzer.
In case you're not familiar with it, check

 

[rock soderstrom]

Makes me think of the Lucas CS-1 designed by Oliver Archut. It has a "secret tube" wired in parallel. Theres a thumbnail of the schematics on the recording hacks site. But it's not possible to enlarge it so the values of some components also remain a secret. I hope that I will come across a Classic 2 so that I can reverse engineer it.

What is the consensus regarding the parallel connection of the two triode systems in microphones? The reasons for this are given on the linked page, but what are the arguments against it? I'm wondering because you hardly ever see it, not in the past and not today...the designers of the AKG C12 did not use the second triode system, for example.I assume that they were aware of the advantages but did not do it anyway. Why?

 

[abbey road d enfer]

but what are the arguments against it?

The main argument is the increase in parasitic (Cgk and Miller) capacitance that significantly attenuates the capsule signal.
In practice, the theoretical 3dB improvement (not 6dB as suggested by Oliver Archut) in S/N due to paralleling tubes is seldom achieved. If the attenuation due to parasitic capacitance is close to 3dB, the net practical benefit is nil.
Of course, paralleling offers more tolerance to the design of the transformer, but using the second half of the tube in CF mode allows even better improvement.

 

[abbey road d enfer]

I should add that the CF option makes the xfmr more "transparent", at least in terms of frequency response and LF distortion, so whatever "colour" is imparted by the xfmr when connected as an anode load is lost in CF.

 

[Matador]

These essential conditions are self-evident, but "just about anything" has to be interpreted as nothing but an impactful phrase. The difference between the Berlin Philharmonic recorded with DPA compared to SM57s (or should I say a mobile phone) will not feel like 10-15%.

Of course, I was being a bit reductive. However I would still prefer to take an iPhone into a great room with a great talent than a U87 into an API console in a subway bathroom with a terrible singer.

A good friend of mine recorded an entire album with SM57's (and SM58's as well) into a 8 channel mic pre I designed based on the INA163, and overall it the album sounded fantastic, once I convinced him to invest in some proper room treatment in his live room (bass trapping in the corners, diffusion on the walls, etc). We even mocked up a temporary vocal booth using heavy moving blankets arranged in a trapezoid.

Obviously rock albums are one thing, where you are (mostly) close miking really loud sources in a controlled space, but I stand by the idea that, at least in my experience, the recording space, the signal source, and microphone placement dominate what is heard in the recorded signal.

I've never tried to record a symphony in a large space, so I can imagine that special considerations are warranted, however I find it hard to wrap my head around the idea that success is solely limited to what kind of EQ curve is in the mike, versus applying EQ curves to the multitrack. It seems akin to saying that one can never eat any food that has been salted.

 

[Cqwet Dbdfte]

I would add that the audience of various genres of music have different expectations. You could close mike a symphony orchestra with 60 odd mikes, but that is not what is expected, nor needed as the performers can handle a live performance without "retakes", while pop & rock close miking would make room acoustics less of an issue, and multi track recording from isolated booths perhaps a necessity. Its audience do not typically expect an acoustic environment from the mostly synthetic sound sources, lacking an acoustic analog. The whole stereo image is a scrap-book construction here, and "everybody" is happy, almost.
The acoustic environment would be more challenging, and as you say have a dominant effect over the possibly minor differences between pieces of equipment and some mike EQ curve. Too reverberant a recording room, or too damped can both be sub-optimal. Finding good recordings in this aspect sadly presents a challenge. I'm not sure what, or who decides what the preferred outcome would be.

 

[Paul W]

Neither am I. I can do that in a matter of minutes with the help of Samplitude's FFT Filter Analyzer.
In case you're not familiar with it, check

It's unclear to me from the video what's actually going on there. Is it just matching the spectrum, for which you'd need very similar performances, or is it trying something cleverer, actually inferring an EQ curve (as distinct from an inferred spectrum of the source)?

 

[tomas.borgstrom]

A good friend of mine recorded an entire album with SM57's

Many good albums are recorded with the same dynamic microphone on all sources.

I would still prefer to take an iPhone into a great room with a great talent than a U87 into an API console in a subway bathroom with a terrible singer.

Me too, but I would like to make it more complicated. If you have a bad artist with a bad song a luxurious chain with a large detailed sound will probably make things even worse. An SM57 into a stompbox will often make more sense in those situations. It's when you have a great artist and a great song with a great arrangement that you have the chance to really enhance the recording with optimizing the recording technique and the recording chain.

I find it hard to wrap my head around the idea that success is solely limited to what kind of EQ curve is in the mike

I can't see that me or anybody else in this thread have made such a statement.

 

[abbey road d enfer]

It's unclear to me from the video what's actually going on there. Is it just matching the spectrum, for which you'd need very similar performances,

That's correct, however it works well at analyzing a full song and acquiring a sonic signature that it applies to a different one.
I never use it that way, because I like tracks to be very distinct.

or is it trying something cleverer, actually inferring an EQ curve (as distinct from an inferred spectrum of the source)?

Both. It modifies the spectrum by applying dynamic EQ.

 

[kingkorg]

I love how this thread didn't turn into $#|t show even though there are quite a few opposing opinions.

 

[ubxf]

It seems like everyone is saying essentially the same thing but looking at it from polar opposites

 

[garp]

Well, i arrived here to maybe learn how to tame HF overbright response of the u87 i have (at least compared to my U67!), thinking that maybe maybe someone can (like in the AKG perception mod) claim that increasing or decreasing a certain cap in the circuit could tune my mics more in a U67 response ... but 4 pages of post later, still no answer ! Can anyone help ? Kingkorg ? (sorry but C6 in the U87 schematics is not 220 pf but 0,1 uf instead and has obviously nothing to do with frequency response of the circuit IMHO, i am confused !).

 

[Khron]

Well, i arrived here to maybe learn how to tame HF overbright response of the u87 i have (at least compared to my U67!), thinking that maybe maybe someone can (like in the AKG perception mod) claim that increasing or decreasing a certain cap in the circuit could tune my mics more in a U67 response ... but 4 pages of post later, still no answer ! Can anyone help ? Kingkorg ? (sorry but C6 in the U87 schematics is not 220 pf but 0,1 uf instead and has obviously nothing to do with frequency response of the circuit IMHO, i am confused !).

Do the components in your (genuine?) U87 have visible component designators?

 

[garp]

Yes they have, i was just asking which capacitor is employed to achieve hf roll off in the schematic, C107 ? C104 ? and yes they are genuine (some 87Ai and some U397 french radio transformerless version) as one of my U67 (the other one is U397 modified with ioaudio guts)

 

[Khron]

in the schematic

Which one? Is it a U87i or U87Ai? Spoilers - there are several versions of schematics for each...

(It's kinda like asking "what brake pads do i need for my red Volvo?")

 

[garp]

As said in my post ... Ai version but U397 shares a lot of similarities with the U87

PS: My Volvo is grey

 

[Khron]

As said in my post ... Ai version

Which one? Is it a U87i or U87Ai? Spoilers - there are several versions of schematics for each...

I was hinting at "maybe try linking a schematic that matches your mic, so we all know what we're talking about / so we're all talking about the same thing..?" But sorry for not being able to read minds...