Another G7 (sigh!) IKEA design

Here is my Gyraf G7, the IKEA version.
Bodytube is IKEA Vika Curry leg. The topbase where I mounted the capsule is the foot of the curry-leg. The pcb is mounted on IKEA Metrik kitchen-handle.
The body is painted with a "neumannish" silver/gold metallic car-laquer. I am using AKG ck-12 capsule, Lundahl trafo and NOS Siemens tube.
Had some troubles with hum and hiss but after calibrating the heater voltage it is now fine.

I have one question though. How much can one expect noise-wise from this project? My G7 is pretty quiet, but my Neumann TLM 103 and my Peluso 2247LE is defenetly quieter. I had to tweak my trimpot in the PSU for the best noise-ratio but I could not get it totally quiet.

Lovely project nevertheless!!!

Henrik

Pictures:

And the background colours are even yellow/blue!  ;D

Looks nice!

Grattis!

Nice, I like this kind of DIY!

What comes to noise I think it's possible to get to the same ballpark with other "inspired by classics" tube mics, like the Peluso. I've read that it's hard to find a quiet EF86 these days so that could be a issue, or something else. But what the heck, noise is trendy, they make even plugins noisy these days

pasarski said:

Nice, I like this kind of DIY!

What comes to noise I think it's possible to get to the same ballpark with other "inspired by classics" tube mics, like the Peluso. I've read that it's hard to find a quiet EF86 these days so that could be a issue, or something else. But what the heck, noise is trendy, they make even plugins noisy these days

Click to expand...

Hehe! You are right, I read about all these tapesimulators with noise-buttons.  ;D
I would like to be able to choose though.
Henrik

Great look and good style.  How did you cut the leg?  Could you write a bit about that?  That might be a good option for me.

Thanks!
min

Make sure you clean the high-z area VERY thoroughly with flux cleaner - this can have a large effect on noise.

Best, Ben

plumsolly said:

Make sure you clean the high-z area VERY thoroughly with flux cleaner - this can have a large effect on noise.

Best, Ben

Click to expand...

Thanks Ben! I have tried to clean the pcb with iso-alcohol. Maybe I should try harder.
I will try to specify the noise:
It´s the "wind"-noise. When I turn my trimpot in the psu I get from a midrange-hiss and hum to a hi-freq-hiss. In the middle it is the best noise-ratio and no hum.
I will try to post some samples when I get to the studio.

Henrik

mista min said:

Great look and good style.  How did you cut the leg?  Could you write a bit about that?  That might be a good option for me.

Thanks!
min

Click to expand...

Thank you min!
I missed out on Skylars nice microphone-bodys. So I decided to make my own. Living in Sweden I dont have mcmaster-carr right around the corner. So I searched quite a while for a good tube. Finally I found the IKEA one. It has a nice finish and is dead cheap.

I took my crosscut-saw and changed the blade to a metalcutter one. It did not fit my saw perfectly but I was able to tighten it enough. Then I cut the leg to the right length and cut out the capsule-holes. The capsule-holes were a bit tricky. I could not cut all the way so I had to bang a screwdriver to it to get them out.
Then quite alot of filing and sanding.  
After handfiling the whole body I found out that I could actually use the crosscut saw as a filing machine. I.e you can trim the bottom of the tube by pressing it gently to the side of the blade. That would have saved me a couple of hours.
The pcb-mount (kitchen-handle) I cut to right length and drilled holes for the pcb and bodymount. I threaded all the holes to be "nut-less".

The design is pretty much the one found on Gyraf´s site.
I don´t know if I would recomend this to anyone when it was a big pita to build. But then I really do not like the metalwork.
It is a very cheap option (something like 12$) and if you are in to metalwork, go for it!
My next microphone will be in a pre-made body.

Henrik

Hmm. "Wind"-noise sounds like a tube problem. Do you have "popping" or "frying" noise as well?

Witch trimpot in the PSU do you mean, the one for setting the heater voltage or the negative feedback trimmer?

The heater voltage should be about 6,3 Volts.

Hi

Beautiful mic body... I got a old IKEA table I wanna throw away... you got me thinking of saving the legs....

What material is the mic body made of? steel? How did you ground the body? Could you solder a ground cable onto the body? Could you solder the grill to the body? Could that be the reason for the noise?

I hope you sort out your noise problems.
All the best
JD

There are a few noise in a tube microphone threads here

How many tubes did you try?  You might need to try a few

How long have you had the microphone powered up?

What are the tube voltages and heater voltage?

Next you can sub in a 50pf to 100pf cap for the capsule and test the noise again, what does the noise sound like?

You need to divide up the circuit to find the noise

capsule, capsule connections to circuit, circuit, power supply, cable

Sredna said:

Hmm. "Wind"-noise sounds like a tube problem. Do you have "popping" or "frying" noise as well?

Witch trimpot in the PSU do you mean, the one for setting the heater voltage or the negative feedback trimmer?

The heater voltage should be about 6,3 Volts.

Click to expand...

No popping or frying noise. Just a little bit of sssshhhh.
The optional trimpot for the heater voltage in the psu.I actually didn´t measure the voltage just put it to the lowest noise.
It might be a tube problem, I will try some tubes when I get the chance. (I caught a fever today so no studio for me today)  :-\
It might be such a small noise that it is acceptable. I just noticed that both my neumann and peluso were more quiet.

Best
Henrik

Matthew Jacobs said:

Hi

Beautiful mic body... I got a old IKEA table I wanna throw away... you got me thinking of saving the legs....

What material is the mic body made of? steel? How did you ground the body? Could you solder a ground cable onto the body? Could you solder the grill to the body? Could that be the reason for the noise?

I hope you sort out your noise problems.
All the best
JD

Click to expand...

Thank you very much!
I belive the legs are made of steel. They were pretty darn hard to saw through. After painting the body I filed away all the color on the inside. The mesh/net is stainless so I could not solder but I glued it all together and had no problem with continuity. There is no hum in the mic so i do not think that is my problem. (if there is a problem)

Henrik

Gus said:

There are a few noise in a tube microphone threads here

How many tubes did you try?   You might need to try a few

How long have you had the microphone powered up?

What are the tube voltages and heater voltage?

Next you can sub in a 50pf to 100pf cap for the capsule and test the noise again, what does the noise sound like?

You need to divide up the circuit to find the noise

capsule, capsule connections to circuit, circuit, power supply, cable

Click to expand...

Yes and I belive I have read them all.
I have five tubes to try, but have not done it yet. Will do though!
I had my mic powered up for about four hours yesterday when comparing to other mics.
Have not measured voltages yet. Will do.
Might try the cap-test. But it seemes to me more like a noisy tube.
I tried to change to my Peluso cable. No differense.

I really apreciate all your answers!
Maybe I am overreacting on this noise issue. It IS a working noisefloor but you always want to improve, don´t you.  

I will try to post some samples when i get rid of this anoying fever.

Henrik

Just a little bit of sssshhhh.

Click to expand...

Is it continous or is it coming and going? (like the wind)

As Gus said, you´d probably have to try out a couple of tubes.

Tubes of the same brand could  have remarkable differencies in noise floor.

Even an expensive NOS "Brand" tube could be useless for microphone use.

Buy a couple of different tubes (even used) on ebay and try them out.

I once bought a quartet of selected (red dot) Telefunken EF86 (diamond, Ulm factory blah blah) witch sounded pretty good but where
useless because of microphonics!  

Sredna said:

Just a little bit of sssshhhh.

Click to expand...

Is it continous or is it coming and going? (like the wind)

As Gus said, you´d probably have to try out a couple of tubes.

Tubes of the same brand could  have remarkable differencies in noise floor.

Even an expensive NOS "Brand" tube could be useless for microphone use.

Buy a couple of different tubes (even used) on ebay and try them out.


I once bought a quartet of selected (red dot) Telefunken EF86 (diamond, Ulm factory blah blah) witch sounded pretty good but where
useless because of microphonics!  

Click to expand...

It is continous.
I will try my 5 NOS tubes. I have to see if there is one that is quieter.

Thanks
Henrik

Nice, I like your IKEA approach! 


You should measure your voltages. Heater voltage for is a very sensitive area; too high or too low voltages can ruin your tube.

EF86 tubes are designed for 6.3 V. A higher voltage is likely to shorten the life of your tube. You shouldn't go too low, either. Not all tubes take underheating well; in the long run, a too low voltage can contaminate the electrodes within the tube. So it's basically down to nominal voltage or slight underheating. Hence, the usual range for EF86 tubes is about 6.0 to 6.3 V.

didnt read the entire thread so if this has been mentioned please ignore. burn the tube in.i had a pretty drastic hiss in my ioaudio mk7 build that disapeared after i kept the mic plugged in for  a few days. dont remember exactly how long.

seavote said:

didnt read the entire thread so if this has been mentionede please ignore. burn the tubein.i had a pretty drastic hiss in my ioaudio mk7 build that disapeared after i kept the mic plugged in for  a few days. dont remember exactly how long.

Click to expand...

Good advice!  Usually burn in should be 72 hours from what I've read and been explained

I will think about the IKEA body... because honestly it's a pretty cheap option, but may not be my first choice.  Get well soon!

Dude, that mic is so cool! You would never know that it was Ikea. Although you should be honest. You got frustrated with the instructions while putting the table together right? I mean, your mic is a much better use for it.  ;D