D-EF47 Tribute To Oliver Archut U47 Build Thread.

[Purplenoise]

I ordered them on the 15th, and I'll still probably be waiting another month for them to show up. I'll probably wait until then to test other things like the EF184. I hate how annoying it is to take apart the U47 body, and I love how it sounds anyway with the EF80...so laziness wins.

Haha I hear you...I have opened the mic so many times to try out stuff that I might need new screws soon. For the ef184 I have replaced the 100k plate resistor with 51k and went back to 100M grid resistors. First session tomorrow with this configuration so we’ll see how it behaves.

 

[JMPGuitars]

Haha I hear you...I have opened the mic so many times to try out stuff that I might need new screws soon. For the ef184 I have replaced the 100k plate resistor with 51k and went back to 100M grid resistors. First session tomorrow with this configuration so we’ll see how it behaves.

Let us know how it goes. Post a demo if you can.

 

[Purplenoise]

Let us know how it goes. Post a demo if you can.

Unfortunately I don’t have permission to post samples from the session but here are my findings:
-Ef184 amperex sounds a little “dryer” and a little less 3D than the tfk ef802. Ef184 has more highs than 802 but the quality of the high end is a little different. 802 is smoother and 184 a little “papery”. 184 definitely a touch more sibilant. 802 has a little more emphasis around 2k and 184 seems to be smoother there with an emphasis a little higher up around 4K. Both tubes sound big in a different way. 184 seems to have more bass but 802 more upper bass “body”.
I would say that the 802 sounds more modern...higher fidelity and 184 more vintage.
Both tubes sound really good and maybe one might compliment a certain capsule more than the other. Also the 184 has a little more gain and is a touch “crunchier” and more compressed.
H+ 5.05 and B+105 for both tubes.
100k resistor replaced by 51k for both tubes.
Grid resistors 100M for 184 and 1G for 802.
Of course this is very subjective and not scientific so you might feel very differently about those tubes.

 

[JMPGuitars]

Unfortunately I don’t have permission to post samples from the session but here are my findings:
-Ef184 amperex sounds a little “dryer” and a little less 3D than the tfk ef802. Ef184 has more highs than 802 but the quality of the high end is a little different. 802 is smoother and 184 a little “papery”. 184 definitely a touch more sibilant. 802 has a little more emphasis around 2k and 184 seems to be smoother there with an emphasis a little higher up around 4K. Both tubes sound big in a different way. 184 seems to have more bass but 802 more upper bass “body”.
I would say that the 802 sounds more modern...higher fidelity and 184 more vintage.
Both tubes sound really good and maybe one might compliment a certain capsule more than the other. Also the 184 has a little more gain and is a touch “crunchier” and more compressed.
H+ 5.05 and B+105 for both tubes.
100k resistor replaced by 51k for both tubes.
Grid resistors 100M for 184 and 1G for 802.
Of course this is very subjective and not scientific so you might feel very differently about those tubes.

Very interesting. Why did you change the grid resistor between the two tubes?

Why did you drop the 100K value?

Things about both of those sound either appealing or like tradeoffs. I hope those capacitors get here soon, or my procrastination of other work might make me experiment with this sooner than later.

Thanks,
Josh

 

[Purplenoise]

Very interesting. Why did you change the grid resistor between the two tubes?

Why did you drop the 100K value?

Things about both of those sound either appealing or like tradeoffs. I hope those resistors get here soon, or my procrastination of other work might make me experiment with this sooner than later.

Thanks,
Josh

The plate resistor was changed to increase the plate current for the ef184 as it’s running a little cold with the 100k after the recommendation of some very knowledgeable members. Also AMI suggested this when using ef802. With ef802 I did 68k to bring the plate current closer to 0.5mA and it sounds good.
For the grid resistors I just thought those values sounded better with each tube. The value of the grid resistors affect not only the low end but the high end as well. Since ef184 was brighter I used 100M.
The new experiment is a Moby bv08 with same ratio but more windings for higher inductance...maybe a better match for ef800 and ef802. Just installed and first tests are very promising. Running an 802 with 68k instead of 100k and H+ at 5.2v

 

[Purplenoise]

So I went back to the original Oliver’s specs ( ef800, 100k plate resistor) and installed a Moby bv08 with extra windings but same ratio. I raised the b+ to 110v and kept h+ at 5.05v. The mic sounds fuller and really smooth with this configuration and the closest so far to the u47 I compared it too. The low end is really wonderful...big and tight.

 

[JMPGuitars]

So I went back to the original Oliver’s specs ( ef800, 100k plate resistor) and installed a Moby bv08 with extra windings but same ratio. I raised the b+ to 110v and kept h+ at 5.05v. The mic sounds fuller and really smooth with this configuration and the closest so far to the u47 I compared it too. The low end is really wonderful...big and tight.

I finally got those .47µF caps you recommended. I put one in C2, and swapped the EF80 for an EF800. I know, I should do one mod at a time, but nah, I hate opening the mic. lol

Anyway, it sounds great. Both ways sound very good, but this I think is more musical, a little more open, and less heavy on the lows (I assume changing the value of C2 shifted the EQ curve). I think the mic definitely cuts through better this way. I may get some better screws (the heads are already stripping, and I barely touched them), and then consider more tube swapping if I get bored or unhappy with the sound. I think this might be my favorite mic.

Thanks,
Josh

 

[Purplenoise]

I finally got those .47µF caps you recommended. I put one in C2, and swapped the EF80 for an EF800. I know, I should do one mod at a time, but nah, I hate opening the mic. lol

Anyway, it sounds great. Both ways sound very good, but this I think is more musical, a little more open, and less heavy on the lows (I assume changing the value of C2 shifted the EQ curve). I think the mic definitely cuts through better this way. I may get some better screws (the heads are already stripping, and I barely touched them), and then consider more tube swapping if I get bored or unhappy with the sound. I think this might be my favorite mic.

Thanks,
Josh

I am glad. The rft mp caps have a nice color in the mids/upper mids. As the cap burns in it will sound even better. Just have the mic on when you are mixing or play some music for a couple of days.

 

[JMPGuitars]

I am glad. The rft mp caps have a nice color in the mids/upper mids. As the cap burns in it will sound even better. Just have the mic on when you are mixing or play some music for a couple of days.

I dunno if a couple days will be enough, but I'll give it a shot. SoZo caps take 100 hours to burn in, in higher voltage, and not metal casing. I guess if you hear an improvement after a couple days, that's cool. But I would expect to hear more change a year or two from now.

 

[Purplenoise]

I dunno if a couple days will be enough, but I'll give it a shot. SoZo caps take 100 hours to burn in, in higher voltage, and not metal casing. I guess if you hear an improvement after a couple days, that's cool. But I would expect to hear more change a year or two from now.

I think the major change is probably after a couple of days. When I build a mic it always sounds kinda off the first couple of days until the components “settle”. Then it starts to smooth out. Of course after a few months it sounds even better.

 

[JMPGuitars]

I think the major change is probably after a couple of days. When I build a mic it always sounds kinda off the first couple of days until the components “settle”. Then it starts to smooth out. Of course after a few months it sounds even better.

Yeah, it's basically the same with speakers. The initial break in makes the biggest (noticeable) difference, but over time they usually get better too.  At least to a certain point anyway.

 

[Purplenoise]

After trying a V-cap OIMP in my m49 build ( coupling cap) and liking the results so much I tried it out in the u47 build. I got to say it sounds really good and the results are similar as in the m49. Smoother more defined tone, more 3D, in a very natural and transparent way but very musical and not clinical at all. I know there is an ongoing debate about “exotic” caps but in this case it made a very positive change to my ears. It feels different...more natural and less “processed” but at the same time not taking anything away from the u47 character. I am very impressed. It still probably needs many hours to brake in but even like this it sounds awesome.

 

[innercityman]

After trying a V-cap OIMP in my m49 build ( coupling cap) and liking the results so much I tried it out in the u47 build.

What kind of caps are you talking about ?

 

[Purplenoise]

What kind of caps are you talking about ?

Mostly nos MP caps. Siemens, Cornell dubilier, sprague etc
The V-cap OIMP is a 1uf 250v in the output

 

[innercityman]

Mostly nos MP caps. Siemens, Cornell dubilier, sprague etc
The V-cap OIMP is a 1uf 250v in the output

Okaaaay... like the one I have in my MK-47...

So fi I follow you, not only the tube and transformer, but also the output cap can improve the sound ?

 

[Purplenoise]

Okaaaay... like the one I have in my MK-47...

So fi I follow you, not only the tube and transformer, but also the output cap can improve the sound ?

Every component changes the sound to a degree. Improve is a strong word to describe something subjective...unless there is something wrong with the component.
Capsule, tube, transformer is the biggest influence...then the output cap. I have found that different types and manufacturers have an audible effect. I happen to like the v-cap a lot and prefer it to other caps in this build ( and the m49) as of now.

 

[Delta Sigma]

Okaaaay... like the one I have in my MK-47...

So fi I follow you, not only the tube and transformer, but also the output cap can improve the sound ?

Your PCB washer is quite close to that resistor leg.

 

[innercityman]

Your PCB washer is quite close to that resistor leg.

You're right, thanks for notifying me. And even if it works like a charm, I'll change that.

 

[dasnevestheo]

Hi there, been using my DIY U47 for a few weeks now and the sound is almost perfect to me

However, I get quite a bit of sibilance and find the 7kHz area quite strong compared to other 47 style mics.
Any advices on how to tame this beast ?

Body : Alctron
Capsule : Beesneez K7b (wired in cardio only, no switch or relay)
PCB : acrylic board / point to point
Tube : Siemens EF80
Transformer : AMI BV08c
Output caps : 2x K42Y-2 PIO Capacitor
PSU : Dany's PCB, set to 105V / 5.05V

Cheers !

 

[Delta Sigma]

Hi there, been using my DIY U47 for a few weeks now and the sound is almost perfect to me

However, I get quite a bit of sibilance and find the 7kHz area quite strong compared to other 47 style mics.
Any advices on how to tame this beast ?

Body : Alctron
Capsule : Beesneez K7b (wired in cardio only, no switch or relay)
PCB : acrylic board / point to point
Tube : Siemens EF80
Transformer : AMI BV08c
Output caps : 2x K42Y-2 PIO Capacitor
PSU : Dany's PCB, set to 105V / 5.05V

Cheers !

When you assemble it, is there a gap between the capsule mounting plate and the mic body?

I'm using a Beesneez K7 (not sure what 'b' is) in one of Dany's bodies. I have no sibilance issues. I did have a 4kHz resonance in my M49. I followed advice from someone in the U47 FET thread and filled that gap with foam. Fixed my 4kHz problem. I used closed cell foam used for paddlesports.