Behringer B1 condenser mic schematics anyone?

[rodabod]

[quote author="Moby"]
Then, if conclusion is that capsule is guilty for HF it's time to give up....is that conclusion :wink:[/quote]

But if I gave you a real K87 you surely wouldn't give up, would you? Go on, try and make a filter for it.

http://www.groupdiy.com/index.php?topic=20652&highlight=capsule++filter

 

[Rossi]

Just noticed a couple of things:

- the Behringer B1 is very similar but not identical with the Studio Projects B1 circuit (both are manufactured at 797 audio). The Behringer has an additional transistor on the rear PCB.

- the output of the SP B1 is impedance balanced.

- looking at the components on my SP B1, I get the impression that it is based on the TLM103 circuit. Nobody here has fully traced that one so far, but Dale once did a rough draft. http://www.groupdiy.com/index.php?topic=2336
Dale's draft is gone, but there is a re-arranged version in PRR's posting.

 

[Moby]

So,you think that TLM's electronics will work better with B1 capsule?

 

[Rossi]

???
No. As I just said, it already has a TLM-style circuit.

 

[Moby]

Sorry I misunderstood you. I still can't figure way to improve electronics :evil:

 

[mrc]

http://www.pelusomicrophonelab.com/capsnmnts.html one of the 89's would probably be the ticket. I think ssomebody has an M7 in the blackmarket, too.
mrc

 

[Moby]

Thanks, yes I'm familiar with Peluso capsules but I don't want to go with capsule upgrade. Well, upgrading 100$ mic with 139$ capsule... I will appreciate if someone can point me to the hf compensation in the B1 circuit. I will try to trace the schemo... :shock:

 

[clintrubber]

[quote author="Rossi"]I suppose the overall character is in the capsule, which, since it is a K87/K103 knock-off, has a substantial treble boost. In the U87 this treble boost is compensated by a filter circuit.[/quote]

Just wondering in general about those capsule boosts on one hand and the filter-counteracting in the mic-electronics on the other hand:

If we assume that despite the capsule-lift there's still enough headroom everywhere (and on the other side noise isn't an issue either), how important is it that the mic-electronics equalize everything ?

It's sure convenient: self contained package (= the mic), no hassle to compensate further down the chain.

But sonically, why not tweak/filter/EQ further down the line until stuff sounds fine ? It may not be the perfect compensation, but even that could be done: measure that specific mic under controlled conditions (impractical but possible) and use whatever 'real' or inside-DAW EQ is suited.


The reason to do it inside the mic might probably very well lie in the invalidy of the made assumptions about headroom or noise, but if these weren't hampering.... ?

So in other words, what's so special about an internal 'linear' filter that it can't be done further down the chain instead ?

I didn't look at the Neumann-circuits again but IIRC there isn't some kind of inherent cancelling trick ongoing; it's just capsule vs filter-circuit.

Bye,

Peter

 

[rodabod]

[quote author="clintrubber"]
If we assume that despite the capsule-lift there's still enough headroom everywhere (and on the other side noise isn't an issue either), how important is it that the mic-electronics equalize everything ?[/quote]

Peter, I've had a few too many Budvars to find the information just now, but it has been mentioned before that the implementation of filtering in the mic circuit does affect the sound. I don't think we have to worry about noise leveles since this is a de-emphasis filter which we are using. I'll see if I can find a text which describes this theory.

On the other hand though, I can't see why not, other than it being a hassle.

 

[Moby]

But sonically, why not tweak/filter/EQ further down the line until stuff sounds fine ? It may not be the perfect compensation, but even that could be done: measure that specific mic under controlled conditions (impractical but possible) and use whatever 'real' or inside-DAW EQ is suited.

Heh , I tried but simply mic sounds poor that way... I have an impression that some hf distortion happen in the mic electronics. BTW I tried to trace PCB but without success

 

[Rossi]

The beauty of filtering in the mic is that the designer knows how, where and how much. Of course, we're not talking about an absolutely linear response. The mic will be optimized for something that sounds good and can be used in many applications. So you may not need any external EQ in many applications, but if you do, the mic is likely to respond well to EQ, because you have a fairly smooth and even response to begin with.

 

[clintrubber]

[quote author="rodabod"][quote author="clintrubber"]
If we assume that despite the capsule-lift there's still enough headroom everywhere (and on the other side noise isn't an issue either), how important is it that the mic-electronics equalize everything ?[/quote]

Peter, I've had a few too many Budvars to find the information just now, but it has been mentioned before that the implementation of filtering in the mic circuit does affect the sound.[/quote]
Hope the Budvar-recovery went smooth :wink:

Sure, it must change the sound, it is filtering - but that might not be what you meant here.

I don't think we have to worry about noise leveles since this is a de-emphasis filter which we are using.

If one had to come up with a potential noise-then-becomes-a-problem mechanism then one could try along these lines, although I don't think it'll really adds up: "More headroom needed to accomodate the HF-peak, so gain must be kept a bit lower in the path up to the filter that we 'want' to place further down the chain. As a consequence the micpre-stage (which is the guy best suited for low-noise amplification) can't do the full job and noise from other stages enters." A poor attempt I'd say, again I don't think it makes much sense...

How much peaking in those capsules are we actually talking about ?

I'll see if I can find a text which describes this theory.

Nice, thanks already.

On the other hand though, I can't see why not, other than it being a hassle.

It would mean that the 'nasty Chinese-capsule-peak' people are complaining about could more or less simply be corrected... for fun we even might design an optimized/adjustable/dedicated EQ for it, eBay may get flooded by correct-your-mic-investment add-on boxes etc etc...

So if this indeed would be true/feasible then I don't understand all the fuzz. More hassle indeed with an add-on, but apart from that...

So we're wondering....


Bye,

Peter

 

[clintrubber]

[quote author="Moby"]

But sonically, why not tweak/filter/EQ further down the line until stuff sounds fine ? It may not be the perfect compensation, but even that could be done: measure that specific mic under controlled conditions (impractical but possible) and use whatever 'real' or inside-DAW EQ is suited.

Heh , I tried but simply mic sounds poor that way... I have an impression that some hf distortion happen in the mic electronics. BTW I tried to trace PCB but without success [/quote]
If levels are such that you touch the corners then it's indeed a problem. But did you try for lower levels as well ? And what kind of EQ ?

Regards,

Peter

 

[clintrubber]

[quote author="Rossi"]The beauty of filtering in the mic is that the designer knows how, where and how much.[/quote]
Sure, that's a big advantage, the cook itself knows best how to add the required things... someone else trying to determine what's needed will likely be more off.

Of course, we're not talking about an absolutely linear response. The mic will be optimized for something that sounds good and can be used in many applications. So you may not need any external EQ in many applications, but if you do, the mic is likely to respond well to EQ, because you have a fairly smooth and even response to begin with.

You sure have a point there; aspiring correction-makers might set up measuring-systems, equalize everything to more or less ruler-flat results (if at all possible) and might end up with a boring sound. The mic-maker will better be able to see & make the whiole picture. Others (the users) might still be able to come up with a decent correction I guess when they skip the ruler.

As I understood (and unsurprisingly) there's an alike thing for speakers: designs that stop after 'having done the Thiele&Small-parameters' and don't tweak further aren't the best ones.

And apart from all this, when the correction is done outside the mic then obviously that filter (the 'hassle add-on' :wink: ) needs to be as quickly in the chain as possible, before subsequent processing.

Bye,

Peter

 

[Moby]

If levels are such that you touch the corners then it's indeed a problem. But did you try for lower levels as well ? And what kind of EQ ?

Don't get me wrong Peter but you went far away from subject. Of course that problem is bigger with louder signal, but can you tel to the singer to sing just the smooth parts on this mic and then for the louder part to change the mic? Simply electronics saturates on the sibilance and after that there is no way to fix the damned thing. About EQ I have Waves SSL, Duende, BT, and lot of other plug eq's...about hardware , Soundcraft Europa desk, Pultec and Focusrite. I hope enough for smoothing Behringer mike ;-)
But to be more precise...does somebody knows where is hf compensation on the damned B1 PCB :green:

 

[clintrubber]

[quote author="Moby"]Don't get me wrong Peter but you went far away from subject. [/quote]
Related I'd say, but sure, nothing B1-specific, I was just wondering in general about this kind of peaking.

Cheers,

Peter

 

[Moby]

He,he, sorry if I was rough but I just try to help my friend. I'm not lazy to experiment with R&C's but don't have a clue where to start :grin:

 

[clintrubber]

[quote author="Moby"]He,he, sorry if I was rough but I just try to help my friend. I'm not lazy to experiment with R&C's but don't have a clue where to start :grin:[/quote]

Hey no problem, you weren't, just determined - and that's OK of course, it's your thread :wink: . Your question just triggered me to bring up something related I've been wondering about.

What I think to have understood so far though is that for peaky capsules like yours might be there's no magic trick 'by adding R&C'. Maybe it improves a bit, but if it won't make a decent jump then another mic or capsule might be a wiser spending of time, money & effort ?

Good luck!

Peter

 

[Moby]

I don't expect miracles from 100$ mic. Just to smooth a sound a bit :grin:

 

[rodabod]

[quote author="clintrubber"][quote author="rodabod"] it has been mentioned before that the implementation of filtering in the mic circuit does affect the sound.[/quote]

Hope the Budvar-recovery went smooth :wink:

Sure, it must change the sound, it is filtering - but that might not be what you meant here.[/quote]

I should have put the word "implementation" in italics. There are different ways we could approach this filtering.

See here: http://recforums.prosoundweb.com/index.php/mv/msg/3157/0/0/13216/

I don't think we have to worry about noise leveles since this is a de-emphasis filter which we are using.

If one had to come up with a potential noise-then-becomes-a-problem mechanism then one could try along these lines, although I don't think it'll really adds up: "More headroom needed to accomodate the HF-peak, so gain must be kept a bit lower in the path up to the filter that we 'want' to place further down the chain. As a consequence the micpre-stage (which is the guy best suited for low-noise amplification) can't do the full job and noise from other stages enters." A poor attempt I'd say, again I don't think it makes much sense...

Peter, do you really think it is such a bad idea? Pre-emphasis is a standard noise reduction technique. Ok, so we might lose the equivalent of say 6dB headroom, but that's only in the top band, and we've saved ourselves noise which could be an issue for some. My only question is regarding where we are filtering - I'm not so sure that say 10KHz and upwards is such an impairment noise-wise. Something following a noise-weighting curve would be more succesful in that respect.

How much peaking in those capsules are we actually talking about ?

At an ill-educated guess (since I don't have response plots for any... maybe JP has some on his site), something maybe in the range of 4-10dB?

Roddy