miktek cv4 diy mod?

[McIrish]

The CV4 has the front at 0v, the backplate at 60v and the back side varies from 0-120vdc.
Does that tell you anything?

Yes, many things
For example:
- voltage value is decent  and usable for most capsules, rather you would not stress the capsule or destroy it.
- For M7 or K47 type capsules you could try go little higher like 65V if PSU let you do that - usual it's a change of two resistors, one inside microphone, other in PSU

What does changing the voltage due to the sound? More headroom? Sorry for the noob questions.

 

[ln76d]

What does changing the voltage due to the sound? More headroom? Sorry for the noob questions.

No, rather hedroom is worse, but these are small differences. With higher polarisation voltage you will get a little bit better sensitivity, so the lower noise, but this is not the case here. Different polarisation voltage have impact on diaphragm stiffness.
It change sensitivity for several frequencies - same capule can sound little bit different with different voltage values. In some capsules it could by minor difference, in some bigger.
From some time on every mike which i build or mod am setting polarisation voltage which gives me best audible result.
Simple option for test is use of potentiometer.
For your microphone you will have to disconnect C1, set omni on PSU (yes - the same procedure as before) and change two resistors R4 and R8 for potentiometer.  After setting new voltage (it can be also lower if the effect is better for your ears) you will have to measure both halfs of petentiometer and replace it with similar values resistors (or leave pot in place) and set new polarisation of back diaphragm voltage in PSU (usual change of one resistor).
Really worth to try.

 

[McIrish]

Just a recap on this thread.
Ben Sneesby sent me out a K7 to replace the M7. Something didn't sound right at all with the M7. It had no high end or low end; just midrange and the polar patterns didn't seem to work correctly when it was in the CV4. Well, the K7 is a GREAT capsule. It sounds big and warm without any sibilance issue at all. On the alto voice I tried it on, it was the perfect fit. I was really feeling like I'd never get the CV4 to sound like I wanted it to. After drawing out the schematics, the basic design of the CV4 was so close to one of Oliver's U47 designs that I knew it had to sound better than it did. The original MikTek capsule is a bit bright and a bit harsh. The K7 capsule completely makes it a new microphone. I'm very pleased with how this turned out. It took a while to get it all sorted out with Ben due to he being in Australia and me in Chicago but the wait was completely worth it. Ben was more than fair about replacing the M7 with a K7.

Thank you to everyone who chimed in to help me get the CV4 sounding like I felt it should.

 

[micaddict]

Just a recap on this thread.
Ben Sneesby sent me out a K7 to replace the M7. Something didn't sound right at all with the M7. It had no high end or low end; just midrange and the polar patterns didn't seem to work correctly when it was in the CV4. Well, the K7 is a GREAT capsule. It sounds big and warm without any sibilance issue at all. On the alto voice I tried it on, it was the perfect fit. I was really feeling like I'd never get the CV4 to sound like I wanted it to. After drawing out the schematics, the basic design of the CV4 was so close to one of Oliver's U47 designs that I knew it had to sound better than it did. The original MikTek capsule is a bit bright and a bit harsh. The K7 capsule completely makes it a new microphone. I'm very pleased with how this turned out. It took a while to get it all sorted out with Ben due to he being in Australia and me in Chicago but the wait was completely worth it. Ben was more than fair about replacing the M7 with a K7.

Thank you to everyone who chimed in to help me get the CV4 sounding like I felt it should.

 

[Coronargakon]

Just a recap on this thread.
Ben Sneesby sent me out a K7 to replace the M7. Something didn't sound right at all with the M7. It had no high end or low end; just midrange and the polar patterns didn't seem to work correctly when it was in the CV4. Well, the K7 is a GREAT capsule. It sounds big and warm without any sibilance issue at all. On the alto voice I tried it on, it was the perfect fit. I was really feeling like I'd never get the CV4 to sound like I wanted it to. After drawing out the schematics, the basic design of the CV4 was so close to one of Oliver's U47 designs that I knew it had to sound better than it did. The original MikTek capsule is a bit bright and a bit harsh. The K7 capsule completely makes it a new microphone. I'm very pleased with how this turned out. It took a while to get it all sorted out with Ben due to he being in Australia and me in Chicago but the wait was completely worth it. Ben was more than fair about replacing the M7 with a K7.

Thank you to everyone who chimed in to help me get the CV4 sounding like I felt it should.

Hi there,
Happy New Year 2024..
Although it is an old thread I would really appreciate if you could share your experience with the BN K7 moded CV4 after passing so long time. Do you still believe that K47 type shines on this mic? I am asking because I am about to make the same step ordering this capsule from Ben..

Thanking you in advance,
Christos

 

[McIrish]

Yep. I use that CV4/BNK7 very often. It's still the favorite on alto vocals. I have a second CV4 that I may try one of Ben's CK12 capsules in that. I currently have one of Ari's Flat 47 capsules in it. It does sound good but it's never won a shootout, so maybe I will try something different. Note, I'm super picky on matching mics to voices and instruments. In all honesty, I could make any of my main tube mics work in most situations, but I have the luxury of being able to compare often.

 

[Coronargakon]

Yep. I use that CV4/BNK7 very often. It's still the favorite on alto vocals. I have a second CV4 that I may try one of Ben's CK12 capsules in that. I currently have one of Ari's Flat 47 capsules in it. It does sound good but it's never won a shootout, so maybe I will try something different. Note, I'm super picky on matching mics to voices and instruments. In all honesty, I could make any of my main tube mics work in most situations, but I have the luxury of being able to compare often.

Thanks for your reply. Really appreciate. I will give a try Beesneez’s K7. Does BNK7’s saddle need any modification in order to be fitted in CV4’s basket? After the fitting the new capsule is centralized inside the basket or it’s top part is covered by basket’s chrome ring… (as intentionally happens to a well respected neumann classic model..)

 

[McIrish]

The original pedestal is a single screw. The K7 is two small screws. I removed the top plate and drilled the holes to use the holder and pedastal that Ben sent.

 

[Coronargakon]

Hi there,

At first I would like to express my deep appreciation to anyone participating to this thread. Their experience and the related enthusiasm for sharing this experience is so helpful especially for persons that create music but their technical knowledge is limited.

I got a used Miktek CV4 a couple of years ago and found as many other owners that the highs are a little bit annoying. I have swapped the stock capsule to a new Beesneez K47 (thanks to the member McIrish) and to my surprise not only the CV4 is having now a very well balanced highs but also the low mids is now more healthy/dominant too. Highly recommend the swapping to K47 from the stock capsule.



An issue that I really need your valuable technical knowledge:

I am getting from the stock PSU a very weak hum which is obvious only when in silent / arming the recording process. This hum was there before swapping the capsule. Measuring the voltage on pin 2 of the 7 pin cable with mic unplugged it provides 6.76V (!). This isn’t outside the 6.3V specs that EF800 accepts for the heating voltage?



I made use of another PSU (Beesneez) that provides 6V via the pin 2 and the CV4 works ok. No hum at all! Dead silent. However after many recording tests of my voice using the Beesneez PSU and carefully comparing the results to the stock PSU I could definitively say that using the stock PSU I am getting more pronounced low mids.



My question is:

Is it normal for the stock PSU to provide 6.76V heating voltage to EF800? If no, is this a point that can be examined by technician for that weak hum I am getting from the stock CV4’s PSU? Using more heating voltage can affecting the low mids behavior of the mic?



Your reply will be highly appreciated.



Christos

 

[Coronargakon]

The original pedestal is a single screw. The K7 is two small screws. I removed the top plate and drilled the holes to use the holder and pedastal that Ben sent.

Thanks McIrish. I have managed to swap the stock capsule and my experience is appearing in the comment #69