Neumann U67 Clone : D-U67 Tube Microphone Build Thread.

[kaguenpituak]

Both...

 

[dmp]

I have a problem , I have a lot of interferences around 6-8k .. with the u87 and u47 (diy) not have. How I can remove? thanks

Sounds like poor grounding / shielding

 

[kaguenpituak]

I have a problem , I have a lot of interferences around 6-8k .. with the u87 and u47 (diy) not have. How I can remove? thanks

Sounds like poor grounding / shielding

Yes, I've already checked grounding. I have also tried wrapping in foil microphone and psu. I tried to put ferrite filters. Can it be more sensitive to interference circuit? I have found that the interference creates a lift (elevator). The beep lasts between 3 seconds and 20 seconds,it is between 6khz and 8 kHz and it is intermittent. Thanks ;D

 

[stitch-o]

Hello all!

I have completed a D67 build - Beezknees capsule, Max's IO transformer and NOS Valvo EF86.
Recently had the mic into a studio to test against a pair of immaculate and very-well conditioned
original U67s. The U67s sounded almost matched in their sound.
First the good - the mic sounds really good in general. Very low noise floor and big sounding.

The D67 had 3 differences -
1) roughly 6dB more of gain - I have emailed studio owner to confirm that the originals are
wired for 30/50 Ohm output as opposed to IO's 250. This would account for the gain discrepancy.
2) Very bassy with a pronounced proximity effect - I am using the Chinese S body suggested.
It definitely rings. I will felt the internal vertical bars and possibly silicone the bottom piece.
Would adding felt to the bottom of the headbasket also possibly help this issue?

3) Biggest thing - Noticeably dull in comparison with the originals. Both originals had the characteristic
"air" and highend articulation U67s are well known for. The D67 seemed veiled and dull, as said.

I have been studying this build thread for possible tweaks but it doesn't seem like anyone has
resolved this dullness issue....or am I missing something....

Cheers and thanks for everyone (especially Dany, what a great catalog of work!!) and their time!

-s

 

[Dylan W]

Did you confirm that the U 67s have the filter intact and have not had the capsules modded (Stephen Paul mod, etc)?

Did you try swapping tubes between the DU-67 and U 67? In my testing, different models of EF86 seem to make a subtle, though noticable, difference in the "tonal balance" of the mic, especially up top.

Hello all!

I have completed a D67 build - Beezknees capsule, Max's IO transformer and NOS Valvo EF86.
Recently had the mic into a studio to test against a pair of immaculate and very-well conditioned
original U67s. The U67s sounded almost matched in their sound.
First the good - the mic sounds really good in general. Very low noise floor and big sounding.

The D67 had 3 differences -
1) roughly 6dB more of gain - I have emailed studio owner to confirm that the originals are
wired for 30/50 Ohm output as opposed to IO's 250. This would account for the gain discrepancy.
2) Very bassy with a pronounced proximity effect - I am using the Chinese S body suggested.
It definitely rings. I will felt the internal vertical bars and possibly silicone the bottom piece.
Would adding felt to the bottom of the headbasket also possibly help this issue?

3) Biggest thing - Noticeably dull in comparison with the originals. Both originals had the characteristic
"air" and highend articulation U67s are well known for. The D67 seemed veiled and dull, as said.

I have been studying this build thread for possible tweaks but it doesn't seem like anyone has
resolved this dullness issue....or am I missing something....

Cheers and thanks for everyone (especially Dany, what a great catalog of work!!) and their time!

-s

 

[stitch-o]

Hi Dylan
Thanks for the reply.
The Capsule is a new BeezKneez U67 repro capsule unmolested.
I am looking at getting a few more EF86s when I can afford it.
Of course the ones Im looking at (GEC, Telefunken) are pricey...
FWIW: From my research, the valvo are the original models in the early U67s.
Dont think my friend would take kindly to me pulling apart his U67s...

The dullness of topend seems like it might be a combination of tweaking C17 value and tube?
But other here have expressed the same results.

Did you confirm that the U 67s have the filter intact and have not had the capsules modded (Stephen Paul mod, etc)?

Did you try swapping tubes between the DU-67 and U 67? In my testing, different models of EF86 seem to make a subtle, though noticable, difference in the "tonal balance" of the mic, especially up top.

Hello all!

I have completed a D67 build - Beezknees capsule, Max's IO transformer and NOS Valvo EF86.
Recently had the mic into a studio to test against a pair of immaculate and very-well conditioned
original U67s. The U67s sounded almost matched in their sound.
First the good - the mic sounds really good in general. Very low noise floor and big sounding.

The D67 had 3 differences -
1) roughly 6dB more of gain - I have emailed studio owner to confirm that the originals are
wired for 30/50 Ohm output as opposed to IO's 250. This would account for the gain discrepancy.
2) Very bassy with a pronounced proximity effect - I am using the Chinese S body suggested.
It definitely rings. I will felt the internal vertical bars and possibly silicone the bottom piece.
Would adding felt to the bottom of the headbasket also possibly help this issue?

3) Biggest thing - Noticeably dull in comparison with the originals. Both originals had the characteristic
"air" and highend articulation U67s are well known for. The D67 seemed veiled and dull, as said.

I have been studying this build thread for possible tweaks but it doesn't seem like anyone has
resolved this dullness issue....or am I missing something....

Cheers and thanks for everyone (especially Dany, what a great catalog of work!!) and their time!

-s

 

[Dylan W]

I was thinking more about the capsules in your friend's U 67s. There are a lot of modded mics out there... some U 67s have had capsules rediaphragmed with thinner material, which significantly affects the top end response. Some have had the filters disabled or modified. Not that this is necessarily the case with your friend's mic, but I don't think you can make an accurate comparison until you know you're working 1:1.

You should also swap the same tubes back and forth if you can, or at least find out what's in your friend's mics.

Hi Dylan
Thanks for the reply.
The Capsule is a new BeezKneez U67 repro capsule unmolested.
I am looking at getting a few more EF86s when I can afford it.
Of course the ones Im looking at (GEC, Telefunken) are pricey...
FWIW: From my research, the valvo are the original models in the early U67s.
Dont think my friend would take kindly to me pulling apart his U67s...

The dullness of topend seems like it might be a combination of tweaking C17 value and tube?
But other here have expressed the same results.

 

[micaddict]

Both originals had the characteristic
"air" and highend articulation U67s are well known for.

It's sooner the opposite, actually. U67s are "known" for being dark sounding microphones, especially by modern standards. Although I personally wouldn't call them dark, airy they are not. (They do take EQ exceptionally well.)
Many (!) U67s have been altered (filters removed), though, to make them sound brighter or more "modern". Pairs included.

As for the added bass in the D67, check if S6 is jumpered. This is a key feature of the U67. Most originals have the 40 Hz roll off activated. It makes the mic less prone to proximity, popping and booming.
This is not the roll off switch (200 Hz) on the body.


Henk

 

[stitch-o]

Hi guys, thanks for the replies,
-Yes the mics are unmolested and in original condition.

-This Jumper?

 

[mickdundee63]

The capsule will of course make the most significant difference. I wouldn't think that a beesneez capsule would sound "dull" in comparison to the original but it will not sound exactly the same as a neumann.

 

[0dbfs]

You could use the CAL input and run plots on all of the mic's to determine whether the head-amp or the capsule is suspect.

Cheers,
jb

 

[poctop]

Important Info

Hi All,  I had a lot of "feedback" regarding the IOaudio transformer configuration for this build and all reported that they had a rather dark microphone ,
this weekend i reskinned some vintage original neumann capsule and finished wrapping up the a D-U67 i have also at home with tele ef86 and IOaudio transformer
and it sounded pretty dark as well,  all reported the same thing with this transformer and i can assure that the De-emphasis is working 100% on this one , in comparaison with what i had handy IE a D-M269c with AMI T67 corrected wiring and a vintage neumann capsule that i reskinned , and it was night and day, i will post sample here soon when i have some time , but it was just awesomely airy and sweet in comparaison with the IOaudio config,  So at this point in time I stronlgy beleive that the resulting sound of the D-67 with IOaudio transformer will sound pretty dark in comparaison with the AMI transformer Since IOaudio transfomer is also pretty lowd end ish it contributes to a more present proximity effect,.  all thing beeing equals i have gathered this feedback for a long time now and there is nothing wrong with those mic , .... it is the way this transformer (IOaudio) sounds afterall in this mic, and there is nothing negative about that dont get me wrong,  those who prefer the darker sound just need to install an IOaudio trannie and those who would like to have the airy thing of the original U67 goes with AMI,
i have heard of no one complaining about a dark mic with the AMI and with the wiring correction for the feedback to work properly the air is just right where it supposed to be,  tweaking the C17 wont affect much the sound of the IOaudio transformer its just the way it sounds.

i would invite anyone here to comment on this topics .

Best To All,
Dany,




 

 

[Jim50hertz]

Isn't the M269 an inherently brighter microphone than a U67?

Thanks for your work on this Dany.

Peace

Jim

 

[stitch-o]

Hi Dan,
Thanks for the astounding amount of dedication to this project!
And to be fair: YES, the mic as is sounds VERY good.
My bar is just a bit more finicky as this mic was being built for a client who want
an exact (as possible) reproduction of a U67 and has used and had access to the best conditioned ones. The IO transformer obviously doesn't quite deliver that sound.

So two questions: is this a matter of tuning of parts around the IO transformer to
tweak the response or should I look to replace the transformer with an AMI brand?
Second - if I do go with the AMI transformer, but already have PCBs for the IO,
is there any way to make the AMI transformer work in this configuration?

CHEERS and many many thanks!!

-s

 

[poctop]

Isn't the M269 an inherently brighter microphone than a U67?

Thanks for your work on this Dany.

Peace

Jim

yes indeed it is but from my experience with both D-67 at some time conclusion is the same + plus i never had a comment on AMI transformer setup that sounded dark
only a tad too bright before with the help of this community we figured out that the  transformer was wired wrong. after that it was perfect
, in this case with the M269c the evidence is just multiplied by a factor 2.
Best,
DAn,

Dan,

 

[poctop]

Hi Dan,
Thanks for the astounding amount of dedication to this project!
And to be fair: YES, the mic as is sounds VERY good.
My bar is just a bit more finicky as this mic was being built for a client who want
an exact (as possible) reproduction of a U67 and has used and had access to the best conditioned ones. The IO transformer obviously doesn't quite deliver that sound.

So two questions: is this a matter of tuning of parts around the IO transformer to
tweak the response or should I look to replace the transformer with an AMI brand?
Second - if I do go with the AMI transformer, but already have PCBs for the IO,
is there any way to make the AMI transformer work in this configuration?

CHEERS and many many thanks!!

-s

IMHO you will need an AMI PCB and then you will be able to reach what you were hoping and  need,
Best,
Dan,

Thanks To dandeurloo a  sound sample with the AMI T67 corrected wiring,
this is what you can expect with this ,

https://cdn.groupbuilder.com/groupdiy/u/39511/58d02819941dd.wav

Best,
Dan,

 

[micaddict]

Isn't the M269 an inherently brighter microphone than a U67?

-c version, yes (self bias); -b version, no (fixed bias, like the U67).
From what I know.
But an AC710 tube doesn't sound exactly like an EF86, of course.

They all have the de-emphasis circuit, mind. That includes the M269c.

 

[stitch-o]

DANY RAWKS!!!

Thank you again for all your amazing attention to detail and work.
I hope to make a pair of ELAMs if the money tree starts flowering... ;D ;D

Cheers!

-s

Hi Dan,
Thanks for the astounding amount of dedication to this project!
And to be fair: YES, the mic as is sounds VERY good.
My bar is just a bit more finicky as this mic was being built for a client who want
an exact (as possible) reproduction of a U67 and has used and had access to the best conditioned ones. The IO transformer obviously doesn't quite deliver that sound.

So two questions: is this a matter of tuning of parts around the IO transformer to
tweak the response or should I look to replace the transformer with an AMI brand?
Second - if I do go with the AMI transformer, but already have PCBs for the IO,
is there any way to make the AMI transformer work in this configuration?

CHEERS and many many thanks!!

-s

IMHO you will need an AMI PCB and then you will be able to reach what you were hoping and  need,
Best,
Dan,

Thanks To dandeurloo a  sound sample with the AMI T67 corrected wiring,
this is what you can expect with this ,

https://dl.dropboxusercontent.com/u/43869772/U67/Feedback%20winding%20Correction/Corrected.wav

Best,
Dan,

 

[ruairioflaherty]

I don't have a horse in the AMI vs IOAudio transformer race but I've owned a U67 for years and used quite a few, both original and the early 90s re-issue.  U67s are not known for being bright or airy, they are also not know for being dark.  A working u67 is wonderfully balanced and has great mid range body and detail, it can take eq really well and if you want airy you just open it up with eq.

I just wanted to point that out for those that have never used one or heard and original.

 

[stitch-o]

Because of the semantic nature of many of these recent response/posts, I'll say I too have used a few U67s.
They have a defined and articulated high end.
I used the word airy because in direct comparison to the two immaculate original U67s -
the IO audio D67 sounded dark and the U67s sounded like there was a distinct high end extension and articulation not present in the IO audio fitted D67, confirmed by two other engineers beside myself.
I called it 'airy'. Guess that word stuck in some jowls... :-X (see tag)