6802 Mods

  • Thread starter Thread starter Marik
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dgatwood said:
I assume these capsules would be the same situation as an MK-012 capsule, i.e. disassemble it, pull out the bare capsule, and sub it into the housing on the 310?
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I would machine an adapter. I don't see a good reason of changing anything in MBHO capsule, also the 310 housing will have completely different acoustical properties.
 
OK, time for some blind tracks--comparison of the modified 6802 and Brauner VM1 ($6000). For now male and female speech. I edited the tracks to cut all aaaa, mmmmmm, etc.
For testing I use modded and remachined 797 Audio capsule, which sound I know very well. About 10" from the mics:






And just for fun two special guests--stock Stellar RM3 and modified ACM3 ribbon mics, which are basically the same, but rebranded mics. Pay attention to the noise difference. Because of proximity effect I was 2' from the mics:




Which is witch? :eek::eek::eek:
 
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Thanks Marik for these clips.

I don't know which is which, but I like sound of your voice in male1 as far as color, but male2 has less sibilance. I notice it even more on the female voice.

Ribbon1 sounds much better to me so I guess that would be the modified ACM-3.

You mentioned that one was phantom powered? Can you explain?

Thanks again!

Earl
 
I'm with Earl on this one. Microphone 1 sounds a lot clearer, although it does pick up the sibilance more. I'd imagine 1 is the Brauner, since it sounds more natural - but I've never had experience with one, so thats just a guess!

If my 6802 sounds like either, I'd be pretty happy.

Ribbon 1 sounds a lot better and less noisy.

Gareth

[Edit]: Marik. When you say the capsule is a modded 797 capsule... is this the "M7" you were speaking of earlier in the thread, or something different. I notice you are also going to try a PK47 capsule - How do you expect this will change the sound compared to the 797? What about a CEK12 style Peulso capsule? Just rough guesses would be good - can't wait to have a go at mine when they arrive after this buy:D

Good Work - Wouldn't have a clue where to start myself, so thank you for sharing this information and experience!
 
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I agree that ribbon #1 is much better than ribbon #2.

for the condensers, #2 has more room noise and less sibilance, and #1 sounds closer and clearer.

I imagine that the 6802 sounds significantly different from when I sent it off to Marik, but I have to say that #1 has some qualities that reminded me of the sound - despite being really high output, it seemed to reject room noise in a weird (but welcome) way.

Is that the same GE tube? I noticed more sibilance in the 6802 before I changed the tube, and the sibilance in #1 seems less like the GE tube, but the [unmodified] 797 capsules I've heard have been more sibilant, so maybe that would explain it.
 
Marik said:
I would machine an adapter. I don't see a good reason of changing anything in MBHO capsule, also the 310 housing will have completely different acoustical properties.
Click to expand...

So I opened up a 310 capsule today and now I understand why you must think I'm on crack. Having only worked with LDCs and PCB-mount SDC capsules, I was under the (I thought fairly natural) assumption that SDC capsule heads would contain a self-contained capsule that would be removable as a unit like LDC capsules and PCB-mount SDC electret capsules. They don't, or at least this one doesn't.

Inside the 310, you have:

  • metal plate that screws in and holds everything together.
  • done-shaped plastic piece that takes up space.
  • plastic piece with metal pin sticking out the bottom that contains electrical contacts and the backplate
  • two very thin plastic washers that serve as spacers
  • a tensioned, gold-plated mylar disk stuck to what amounts to a washer, give or take.

all simply placed together in a sandwich, held only by the metal screw plate and the outside of the capsule enclosure.

Guess that pretty much precludes any sort of capsule swap short of buying a CNC mill. Not that I'd mind owning one or anything, but where the heck would I put it? :D Okay, these seem tempting...

Before I go off the deep end and spend three grand on a CNC mill, I don't suppose I could convince you to get into the adapter manufacturing business, could I? :D
 
earlwgreen said:
You mentioned that one was phantom powered? Can you explain?
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Besides a usual transformer it has an electronic circuit inside.

gareth.h.rees said:
When you say the capsule is a modded 797 capsule... is this the "M7" you were speaking of earlier in the thread, or something different. I notice you are also going to try a PK47 capsule - How do you expect this will change the sound compared to the 797? What about a CEK12 style Peulso capsule?
Click to expand...

No, it is not M7, but K67/87 style. The reason is I know the sound of this capsule very well, so it is much easier for me to fine tune the circuit. Also, since the comparison is with Brauner, which has that style of capsule it would be meaningless to test it against the M7/K47 style--kinda apples vs. oranges.
I will post later the PK47 vs. Gefell UM70/MV672 with original M7.
I never heard CEK12, but since it has a K67/87 style backplates the fact it is advertised as AKG CK12 (which is a 5 chamber design) style is misleading.

I will leave the opportunity to guess for another day or two and then reveal the "who is who".

dgatwood said:
Before I go off the deep end and spend three grand on a CNC mill, I don't suppose I could convince you to get into the adapter manufacturing business, could I? :D
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You bet!
It takes so much time to set all the machinery up and is such a tedious work that I hate doing it even for myself, esp. considering different thread pitch and diameter. It would be just way too expensive for such limited quantities.

The best I can do is to remachine the stock capsule.

Best, M
 
Perhaps I missed this info somewhere along the way, but can someone recommend a good tube to replace the stock one? Links to items on ebay or online stores would be greatly appreciated.

Thanks,
Ryan
 
I had good luck with a NOS GE 12AT7 that I got from a shop down the street (which, as far as I know, doesn't sell over the internet). Replacing the stock tube with that one made for a mellower sound that I preferred.

I can't personally recommend a seller (unless, despite your "location", you live in Houston, TX, USA in which case, PM me), but a web search shows a bunch of sources, ranging from around $10 to $40 or so.

Marik modified the 6802T in a way that preserved its compatibility with the 12AT7 (thanks again!!!!! btw - I know that must have made it a bigger project than it could have been). Both Marik and Oliver Archut (the maker of the replacement transformer) recommend a 6072a tube now, but I'm not 100% sure that will work the same way with the stock 6802T microphone. I was able to get a plain old 6072 (without the "a"), from that same store and will try it out when I get the mic back.
 
i have a NOS GE JAN 6072a in my 6802T and it sounds awesome.
 
OK, I think it is time to reveal things.
On both, male and female recordings the #1 is the 6802 with my modified 797 Audio capsule and # 2 is the Brauner.
I think it is important to notice, I voiced this 797 capsule for instrumental use, particularly to make it suite the classical piano recording, which requires a deep bass and crispy high end--the reason it gives little more sibilance with voice. There would be no problem to voice it any other way.

Of course, Gus, who I believe owns the Brauner and knows the AMI transformer sound could immediately spot "which is witch" :).

With the mic as it is (with that particular capsule and that particular transformer) I like the 12AT7 better, as it is more lively and gives more spark. The GE 5star 6072 on the other hand, is mellower and more subdued, and might take care of that extra sibilance. I will try to make a clip with it.

Best, M

Edit: Oh, and the #1 ribbon is the modified one.
 
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Marik.

WOW!:eek:

VERY nice work! Maybe its just my amateurism, but I prefer the modded 6802 to the Brauner..! I can guess that the Brauner would make things sit less forward in a mix so obviously this would be a useful characteristic, but just WOW, the modded 6802 sounds great.

Which do you find to be the most "accurate" representation of you and your wife's voices?

Also, may I ask how much this mod has cost so far? I understand that your capsule is not directly purchaseable (or is it?;)), but if you could give a rough estimate of how much "extra" you've put into this mic that would be great.

Do you have any other "commercial" mics to which this mic compares to in terms of sound character?

Can't wait to hear the M7 style capsule in this mic - it will be a nice educational process listening to the different verieties!

Thanks for all the hard work you're putting in to this - expect lots of questions when I get my hands on mine:D:D

Thanks
Gareth
 
Marik,

I am super impressed with the 6802. Can you tell us how much the mod would cost for another 6802? Also, would these mods work on the ACM1200?

Just curious.

Earl
 
Thanks for the responses on my tube question. Anyone have a preferred vendor for purchasing both a GE 5star 6072 and a 12AT7? I'd like to try them both out, but don't know where to buy them.
 
gareth.h.rees said:
Also, may I ask how much this mod has cost so far? I understand that your capsule is not directly purchaseable (or is it?;)), but if you could give a rough estimate of how much "extra" you've put into this mic that would be great.
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From my side, the parts I had shipped to Marik so far were ~260 for the PK47 capsule and ~180 for the BV314 transformer. Photos indicate that he put some other parts in there (wima capacitors, certainly). There's there's the inescapable issue of skill and tools :D, but I'm not sure if you're asking for a quantification of that.
 
Marik said:
The PSU top:
http://home.comcast.net/~markfuksman/TNC6802_PSU.JPG
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Marik, this is the same supply as the "fake" Oktava one which came with the MKL2500!

The connectors are poor quality. Also, check the earth tag which is screwed onto the mains transformer lug. My transformer is laquer coated, so the earth tag was insulated from the case!

I still have a very slight resisdual hum issue with mine, but I'm not sure if it is to so with the grounding. Pin1 and the chassis earth are connected at the XLR on mine.
 
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