miktek cv4 diy mod?

arnesl · Jan 28, 2016

Hi
Have anyone done a successful diy mod to the cv4?
I know I could send it away, but it's a long way to send it.

I am thinking change capsule and maybe turn down compression.

the mic in real good condition so an alternative might be to sell and build/buy a new mic.

Any opinions on this?
Thanks.
Asl

Khron · Jan 28, 2016

According to RecordingHacks,

http://recordinghacks.com/microphones/Miktek/CV4

it has a K67-type capsule, so replacing that would / should indeed alter the character of the mic. Either a K47-type or a CK12-type ought to work fine, i'd guess

Can't guarantee it'll sound "better" (because that ultimately depends on the source AND the placement), but it would/will definitely sound different

rodaffleck · Jan 28, 2016

I love modding and diy (because you know, why else would I be here

) but taking a scalpel to a microphone that costs $1600 to begin with, appears to have some quality components inside it, and was designed in part with someone--presumably Oliver--at AMI doesn't strike me as an ideal project. I'd be more inclined to sell it as-is if it's not making you happy.

That being said, given the mic's lineage and the fact that it has an EF800 and an AMI transformer, I'd be curious to know how close the circuit is to Oliver's U47 alternate tube schematic (found here: http://www.tab-funkenwerk.com/id68.html ) If it's actually the same circuit or at least close to it, then swapping out the stock tube for an mk47 style might actually make sense. At the very least I suppose it would be a mod that you could easily reverse. I can find very little information on the BT4 transformer that the CV4 uses so I have no idea if it's a BV8 derivative or something else completely.

kidvybes · Jan 28, 2016

rodaffleck said:
I can find very little information on the BT4 transformer that the CV4 uses so I have no idea if it's a BV8 derivative or something else completely.

...just a different model # (for Miktek) applied to one of Oliver's standard BV8 transformers...I had discussed this mic with him...Shannon Rhoades of Mic Rehab in Nashville has also had some input on those mics and does a wonderful modification...here's a thread link dealing with the modded CV4:
http://realgearonline.com/thread/5/new-miktek-cv4-mod-soundfiles

arnesl · Jan 29, 2016

>>but taking a scalpel to a microphone that costs $1600 to begin with

rodaffleck said:
I love modding and diy (because you know, why else would I be here ) but taking a scalpel to a microphone that costs $1600 to begin with, appears to have some quality components inside it, and was designed in part with someone--presumably Oliver--at AMI doesn't strike me as an ideal project. I'd be more inclined to sell it as-is if it's not making you happy.

Yes, you might be right about this, if I can get what I want for it I might sell it,.
on the other hand the curious part of my want to mod it

change the capsule I wound not think twice about testing if I decide not to sell it, but moding the circuit is something else.

Khron said:
According to RecordingHacks,

http://recordinghacks.com/microphones/Miktek/CV4

it has a K67-type capsule, so replacing that would / should indeed alter the character of the mic. Either a K47-type or a CK12-type ought to work fine, i'd guess Can't guarantee it'll sound "better" (because that ultimately depends on the source AND the placement), but it would/will definitely sound different

So do you mean/think/know that this is also a flat circuit used with a K67 capsule, and does not have HF compensation for the K67 type? could almost sound that way.

kidvybes said:
rodaffleck said:

I can find very little information on the BT4 transformer that the CV4 uses so I have no idea if it's a BV8 derivative or something else completely.

Click to expand...

...just a different model # (for Miktek) applied to one of Oliver's standard BV8 transformers...I had discussed this mic with him...Shannon Rhoades of Mic Rehab in Nashville has also had some input on those mics and does a wonderful modification...here's a thread link dealing with the modded CV4:
http://realgearonline.com/thread/5/new-miktek-cv4-mod-soundfiles

I know about this mod and it sounds good, have considered, but it is a long way to send it for starters.

Khron · Jan 29, 2016

Between "All the chinese zing - gone", and "trying to replicate a certain 251 that they were in love with", you can bet your bottom dollar they started with the capsule

Can't have a 251 without a CK12 now, can you?

Add to that this post: http://realgearonline.com/post/53/thread

ln76d · Jan 30, 2016

Few things!

What is wrong with your cv4?
What effect you want to achieve?
What is "compression" in microphone, from your point of view?
Did you considered first to try mod the elctronics inside the mic?

According to the frequency response graphs, in my opinion, it isn't flat amplifier if it use k67.

arnesl · Jan 30, 2016

All good questions.
The shot answer might be that it is not the right mic for me.
But it has some qualities I like especial on softer vocal.
I would never buy this mic with the purpose to mod it, I liked when I got it but I have sort of gone of the sound over time.
I think it true what some say, that sound quality must be evaluated over time.

>>compression
Maybe head room is more correct , but am not quit sure what is causing the effect that i do not like in some cases.
Some kind if HF saturation that is too much for me. or might this be what is refereed to as "chinese zing"
It seems when you push a bit on vocals it sort of defaults to one type of sound that is a bit annoying.
I maybe a combination of things.

I was not considering modding the circuit, without changing the capsule.

Frequency response graphs
that is probably true it has some kind of HF compensation.

One interesting thought is how it would sound with better K67 capsule
(i mean something the Sennheiser/Neuman K67).

But, I am still looking in to selling it. actually a I have 2 and will probably keep one.

ln76d · Jan 30, 2016

With better k67 it would probably sound similar.
If you need darker mic, you could try m7.
I think it is worth to try tweak circuit first, especially if it had hf attenuation circuit in it.
You could try, for test, connect between plate (after plate resistor) and ground - capacitor from 300-600pf range.
What preamp you are using?

Bowie · Jan 30, 2016

arnesl said:
The shot answer might be that it is not the right mic for me.

Consider the fact that with mid-priced production mics, any mods you perform yourself are unlikely to increase the value of the mic by much and may possibly hurt re-sale. This is because potential buyers trust the companies that make the mics, not individual owners who alter them.
If you don't like the mic now, do you really want to sink $$$ into it, only to end up losing money and time if/when you go to sell it? I always recommend that people start with something they like and make it into something they love.

ln76d · Jan 30, 2016

Buying microphones like miktek, from the start isn't good move if you consider sell it on second hand market.
If you have a head on your shoulders, you can restore original circuit without any problem, so why not to try?
I believe that miktek is decent microphone, so possible modifications could be minimal.
It isn't chinese microphone, where in most cases, best modification is using only the body and possibly the capsule

I think if the autor of the topic want to try different capsule, first should know the circuit, especially if there's LPF in it.
Even find only LPF part.

arnesl · Jan 30, 2016

Just to be clear, if I choose to start to mod it, I have no intent of try to selling it any time soon, my thinking was that it is one or the other, not mod it and then sell it.

It is more like: i will see what i can get for it and if not what i want i might try to mod it.

Yes, I should probably go trough and draw up the circuit before i do anything to the mic.

Khron · Jan 30, 2016

I have certain doubts it's anything overly complicated. I wouldn't be surprised if it were one of the "standard" circuits - a 12A_7, with the second triode not used, or employed as a plate- or cathode-follower, or perhaps a pentode.

ln76d · Jan 30, 2016

12a_7 (except 12ay7) are mostly chinese standard

Here it's EF800 pentode and since it use AMI transformer, there's possibility that Olivier Archut had something to do with the circuit.
Since it is midprice range mike i believe it has common cathode circuit.
If you look on many classic microphones schematic, they share similar topology - both mentioned, cathode follower is less common.
Most important is what (and where) values of components were used.
What are the additional parts of the circuit like LPF or some possibly feedback patches.
How the circuit is "tuned" and what could improve the sound or could show real response of potential new capsule (like removing lpf for example).
Without knowing where's LPF and how it can be disabled, every new capsule (especially with "darker" response) can sound like sh**t

ln76d · Jan 30, 2016

arnesl said:
Just to be clear, if I choose to start to mod it, I have no intent of try to selling it any time soon, my thinking was that it is one or the other, not mod it and then sell it.

It is more like: i will see what i can get for it and if not what i want i might try to mod it.

Yes, I should probably go trough and draw up the circuit before i do anything to the mic.

Could you share what preamp (or preamps) mostly you are using with miktek?

arnesl · Feb 1, 2016

I have one tube preamp (hamptone) , and the rest pretty far to the clean /transparent end of the scale. I would like the mic to work well with "clean" preamps. I do not want to start any discussion about that.but has a little bit to do with freedom/portability.
I understand there are different view on this and even within transformer less pres there are differences. but Id rather change the mic.

I have currently lent a cv4 away in return for testing a Violet Globe standard, mostly out of curiosity as it kind of strange mic (to me), i knew little about. But has generally got good reviews.

arnesl · Feb 2, 2016

Have to take the one cv4 apart anyway it seems, the soldering/ wires between tube socket and pcb are really bad.

Khron · Feb 2, 2016

Might as well lift the circuit then, hmm?

arnesl · Feb 2, 2016

I know what you are saying, I will see, first priority is to fix it now, then might just get rid of both cv4s, and stick more to building from scratch. I have some nice (i think ) capsules ordered so I need some circuits, but I think I will stick more to fets

arnesl · Feb 4, 2016

Turns out also one cap in the power supply is seriously blown the right one (bottom), it seems the top of both of these caps are bending a bit upward (looks a bit unsettling), but I guess either they blow or they are ok there nothing in between, like warmed up thin can

I will probably order 4-5 just to be sure. The caps are jacek the 10000uF and the others rubycon, 22uF should i consider replacing all those caps with something else while a am at it? they do not pass audio as such, i think it is only about powersupply noise?

(this is not related some much to the initial mod question, i have not tried anything yet other than fixing, the mic i thought was in mint condition turned out had some issues, still do not know how that happened. but it now works fine with the other power supply is seems.)

Thanks

A

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