Topic: MXL 990, 991 and Oktava 319 Mods

[Chuck]

Those cheap capsules on eBay are meant for this style mic:

http://www.mxlmics.com/products/900_series/993/993%20.html

I have not done much research on these.

[kirk97132]

Electret capsules, I looked at mouser and digikey  options but I don't think that there is a drop in replacement.  I don't know if I want to get into retro fitting one into the head assembly. 

I do know that the ADK SC bodies will fit their own Zigma capsules but those capsules will not fit the MXL mic bodies.  And I guess not all of the capsules interchange due to center pin lengths head mounting styles and thread pitch. 


797 makes a crap load of stuff for a crap load of manufacturers.  From what I have gather some of the products them make have better QC due to the manufacturers requiring it from them.  At one point I had contacted them regarding buying a 414 clone but they will not sell some of there stuff in the US...imagine that  

I am assuming that list of mics are all true condensers?  And then there would be a list of Electret capsule mics?

Here is a a question, what about the Karma K-10? 

[illconditioned]

797 makes a crap load of stuff for a crap load of manufacturers.  From what I have gather some of the products them make have better QC due to the manufacturers requiring it from them. 

That is exactly it.  I've heard bad things about Apex mics, for example.  And I tried one (a stereo USB mic) and it had all kinds of hissing/popping noises in it.  I'm guessing a MXL or similar mic is the place to start.  Those will have decent QC.  Oh yeah, I'm guessing a lot of the QC is in the capsules themselves.


  Richard

[Chuck]

I am assuming that list of mics are all true condensers?  And then there would be a list of Electret capsule mics?
Here is a a question, what about the Karma K-10?

I've been doing some research on this. That list is all condensers that start out as the basic China 797 Schoeps circuit mic. There are some differences. Some of the capsules have that heavy metal front grill. Some of the bodies have more or different vent openings. Some of the circuits have different component values. Some use better quality components, etc...

Like Richard, I've investigated most of the low cost electrets, but they don't appeal to me as much as the gold sputtered condensers mentioned here.

As far as the Karma mic... I excluded it from the list, even though it uses the same capsules, because it's got a transformer in it and the others do not. It also has surface mount components, which are not user friendly for typical mic moders.

I'm getting to the point where I can hardly work on through-hole circuits anymore because of my eyes and arthritis. So, SMT is definitely not for me. 

[bugg100]

the apex 185 card caps have the grill with screen behind. the omnis are a screen front style cap. the busman caps are all screen front as far as i can tell.

i wouldn't be suprised that one of these low cost usb mics sucked, but i don't feel tbat either of my pair of apex 185s suffer for lack of qc. ( or at least any more than any of the others in this class!)

the 993 mxl's are the same topology as the 603 clones but different case.... the question becomes whether the pins meet for electrical contact and how the extra vents would affect performance.

$8 is  certainly cheap enough to experiment with if they do contact.... maybe micheal will chime in soon about the 993 caps soon!

Joe

[Chuck]

I cross posted over at GearSlutz

http://www.gearslutz.com/board/low-end-theory/395643-best-budget-mics-my-recommendations-19.html#post5993278

and Michael responded with this:

The 993 has the same pronounced HF peak (8dB@8khz or so) as the 603, CM-90, 1200 etc mics due to a combination of the capsule diaphragm tension, backplate design and acoustic chambers in front and behind the diaphragm. It takes a comprehensive modification of the capsule system to remove the narrow-band HF peak from these mics without attenuating the 16kHz air.

It's seems strange to me that they made the bodies longer, and they added vents to the capsules, but the same capsule frequency anomalies persist  Why didn't they address some of the frequency issues of the earlier production runs and improve them in the next runs?

One good thing is that there is plenty of information to be found online for this type of microphone for moders.
I didn't have a good understanding of the issues involved in making quality microphones when I first started digging into these. Now, I'm starting to realize that it's just not that easy to make great sounding mics.

[chris319]

Here is my DIY frequency response curve for an MXL 991 with a cardioid capsule, after having replaced the stock ceramic capacitors.

[OOK]

Here is the stock curve for the 991 from the MXL site for comparison...........The card pattern is more wide card than card...



 

[kirk97132]

I know you said it is a DIY graph.  But wow, that seems like a sharp valley at ~6.3K and quite the hump between 9K & 16K.  Does the 2dB or so opposites give a flat type of sound?  After reading that back to myself it doesn't make a lot of sense so I guess what I'm wondering is how different does it sound?   How accurate do you think your readings are? 

[chris319]

There is one caveat in the fine print of my curve: it is a 1/12 octave curve. Generally in mic measurement 1/3 octave curves are used. My curve has less smoothing because measurements are taken at a narrower spacing of frequencies than a 1/3-octave curve (assuming the manufacturer has put out an honest curve which hasn't been "embellished").

I do not have an anechoic chamber, but reflections can be neutralized in today's software using a Fast Fourier Transform -- you just have to know how to manage them. I am pretty certain about that 6 kHz notch. Other mics I have tested do not exhibit this notch, so I have ruled out the room, the setup, etc. I have a pair of AKG Perception 150s which I have measured; one has a notch just before the presence peak and the other doesn't. This makes me think that the reason a $100 mic sells for $100 is that the manufacturer does not do much in the way of quality control, such as discarding capsules that are way out of spec.

[chris319]

You're making a lot of assumptions about my setup without first having it explained to you.

I use an omnidirectional (no proximity effect) reference mic which has been calibrated by an acoustical laboratory. The distance from sound source to mic is kept constant at 24". When mics are changed they are moved to maintain this distance. The FFT resolution is on the order of 3 Hz. I have measured several dynamic mics and some of them have a great deal of low-end roll-off, so if a mic doesn't have low-end response it will show up in the curve.

I actually own two calibrated omnidirectional reference mics. When measured one against the other the frequency response curves cancel at 0 dB plus or minus one dB or so from 20 Hz to 20 kHz, close enough for me.

[chris319]

Attached is a curve for an omnidirectional E-V RE85 showing very little low-end response. All you have to do is listen to this mic to hear the lack of low end. Also attached is a curve for a cardioid E-V N/D 367s measured at 24". If proximity effect were an issue it would likely show up in this curve.

[dogmusic]

This search: http://shop.ebay.com/?_from=R40&_trksid=m570&_nkw=MXL+capsules
brings up a Hong Kong vendor selling $7.49 capsules on eBay. But it's my understanding that the center pin connector does not make contact with the center pin on the 603 style mics. Also, the cardioid version and hyper-cardioid version have the venting on the capsule, if you look closely.

I was looking at buying the omni version of those capsules for my 603's. Where did you learn that the center pin connector does not make contact with the center pin on the 603 style mics?

Phillip

[Chuck]

This search: http://shop.ebay.com/?_from=R40&_trksid=m570&_nkw=MXL+capsules
brings up a Hong Kong vendor selling $7.49 capsules on eBay. But it's my understanding that the center pin connector does not make contact with the center pin on the 603 style mics. Also, the cardioid version and hyper-cardioid version have the venting on the capsule, if you look closely.

I was looking at buying the omni version of those capsules for my 603's. Where did you learn that the center pin connector does not make contact with the center pin on the 603 style mics?

Phillip

Through reading various threads on the Gearslutz and Prodigy-pro message boards.
I have not tried putting those caps on my mics. So, I do not have first hand knowledge.

[bugg100]

jim jacobsen responeded as such on gearslutz recently.... 

frontendaudio sells them seperate and in the past they have been on ebay. chris busman, a member here sells them also. and he is one of the few with hypers.....

joe