DiY AMI U47

[Matador]

They are both cardioid. The main difference ends up being S/N. The U-47 and all of the other mics that use this type of pattern switching have a lower noise floor due to the fact that the back diaphragm isn't adding additional noise to the circuit in cardioid. The pattern switching is not exclusive to the U-47.

-James-

Do you have a source for this, or can point me to some measurement data?  I would be curious to see what the measured differences were.

 

[scott_humphrey]

[/quote]

Do you have a source for this, or can point me to some measurement data?  I would be curious to see what the measured differences were.
[/quote]

From the Lawson website: "The MK II features both a multi-pattern mode and a cardioid-only mode that increases sensitivity by 3 dB and lowers the noise floor of the microphone by the same amount…."

On my U47-style mic if you switch from cardioid to omni the signal level definitely drops and I have to turn up the gain on the mic pre to match levels. Assuming that you have a good, clean build the noise level isn't much of an issue in my experience, even though theoretically there is less self noise with the back of the capsule disengaged.

 

[Melodeath00]

I got the chance to test out the ADK T-FET Berlin 47 for a few minutes last night, so I decided to compare it to my hand-built DiY U47 since they should be int he same family. As you know if you've read this thread, my DiY U47 features a BeesNeez K7 capsule, AMI BV8, and Telefunken EF800 tube, built point to point by yours truly. The ADK is a FET, not a tube mic, but it also features a transformer and 47-family voicing. The ADK FET is designed for soft-saturation like a tube, from what I understand. Unfortunately I had a very busy night, so I did this shootout in probably 10 minutes total, so it's just for fun. Voice, strummed acoustic, and fingerpicked acoustic. Feel free to listen and comment, and make a guess if you so wish. As for which sounds "closer" to a U47, I have no idea, as I have never used the genuine article.

Each test is its own; meaning mic "A" is not necessarily the same mic in each test.

Voice
https://www.dropbox.com/s/j3ze3mrmmcu4bap/Voice%20A.mp3
https://www.dropbox.com/s/2r8asw9yt1hzn5r/Voice%20B.mp3

Strummed
https://www.dropbox.com/s/y3plr4k12ir6gey/Strumming%20A.mp3
https://www.dropbox.com/s/lmgotpdsswld1bm/Strumming%20B.mp3

Finger-style
https://www.dropbox.com/s/lad9iwd4geb6tz0/Fingerpick%20A.mp3
https://www.dropbox.com/s/266a61a1zzbkblf/Fingerpick%20B.mp3

 

[Aaronrash]

I preferred mic A for voice, some extra mojo going on. I hope it's the diy build because I am planning on building one of these. What the results for voice!?

For guitar I preferred B for both takes

 

[o3misha]

A  is ADK? Its much quieter than B.  A files have bigger low end, but lower middle a little boring. B files are full of harmonics,  bigger lower mid  but not enough bottom. The guitar will suit both depending on the situation. On the voiceover A noticeably easier to further processing than B.

 

[Melodeath00]

I preferred mic A for voice, some extra mojo going on. I hope it's the diy build because I am planning on building one of these. What the results for voice!?

For guitar I preferred B for both takes

Hi Aaron, you have good ears and are in luck. For voice, A is the Diy, and for both guitar, B is the DiY. So you preferred the DiY in all three tests.

A  is ADK? Its much quieter than B.  A files have bigger low end, but lower middle a little boring. B files are full of harmonics,  bigger lower mid  but not enough bottom. The guitar will suit both depending on the situation. On the voiceover A noticeably easier to further processing than B.

Hi o3misha - A is quiter than B? Do you mean noise-wise, or level? I made sure all the files were volume matched by dB RMS. It sounds like you prefer A on voice, but I wasn't sure what else you were saying because A on voice is not necessarily the same mic as A on the guitar.

 

[Moby]

I prefer A for voice but for the guitars I can't say because I have a feeling that mic's are not in same axes.
Also, the background noise is aful

 

[Melodeath00]

Can you please tell me where you are hearing noise? Neither mic sounds noisy to me. Do you mean the room sound possibly? Is it at the end of the fingerpick example? If so, you're probably hearing the fans of my laptop at full speed, as opposed to mic noise.

The mics were aligned vertically and I played with the soundhole as close to between the mics as possible. But again, I did this shootout very quickly. The differences in the voice seem to match the differences in the guitar, IMHO.


BTW: I'm still planning to try out some more EF800 tubes and see how they affect the response of the mic, as well as doing some definitive frequency response sweeps to discover the objective differences. The ADK definitely has more 5kHz than the DiY, which seems to have more lows, and more "air."

 

[Aaronrash]

Awesome!

What tube and capsule did you use for your build? It really does sound good. Congrats man

Edit: oops I read your full post and got my answer

Do you know what voltage the capsule is being biased at? Maybe 60V like the original?

 

[Aaronrash]

Ok so I'm not trying to hijack the thread but I figured this would be a good place to post before I start my quest to building my U47. Now I know allot of purist believe that it's not a 47 without a VF14, I have to say... I had the chance to hear a Flea U47 with a EF12 against a vintage U47 with a VF14 and to be honest I preferred the Flea with the EF12 tube. It sounded absolutely amazing and I told myself I have to have this sound.

So my plans are to use Oliver's schematic with the alternate power supply. A Flea F7 capsule and the AMI transformer as well as kit of course. The only problem is, I have not been able to find much technical information on the EF12 and I'm not even sure if it will work with Oliver's circuit. But I know Flea has figured it out and that's how they sell their mics so I know it's possible

Aaron

 

[melodeath]

Awesome!

What tube and capsule did you use for your build? It really does sound good. Congrats man

Edit: oops I read your full post and got my answer

Do you know what voltage the capsule is being biased at? Maybe 60V like the original?

Yes, the capsule polarization is 60V. Actually a tiny bit less if I recall correctly based on my multimeter. Maybe 57 or 59V.

Also of note, I am using remote pattern switching, so if I disconnected the rear diaphragm, perhaps the sound would be a bit different. They say the s/n ratio improves, although I am not displeased at all with my noise performance. I'm shocked it's so quiet, especially considering my inexperience.

Ok so I'm not trying to hijack the thread but I figured this would be a good place to post before I start my quest to building my U47. Now I know allot of purist believe that it's not a 47 without a VF14, I have to say... I had the chance to hear a Flea U47 with a EF12 against a vintage U47 with a VF14 and to be honest I preferred the Flea with the EF12 tube. It sounded absolutely amazing and I told myself I have to have this sound.

So my plans are to use Oliver's schematic with the alternate power supply. A Flea F7 capsule and the AMI transformer as well as kit of course. The only problem is, I have not been able to find much technical information on the EF12 and I'm not even sure if it will work with Oliver's circuit. But I know Flea has figured it out and that's how they sell their mics so I know it's possible

Aaron

Can you describe the difference between the Flea and U47?

You might want to check this thread - http://groupdiy.com/index.php?topic=42566.0
I have not read the entire thing, so I do not know if the answer lies within, but it seems like the perfect place to start. Definitely keep us updated on your progress.

I know that ultimately I decided the EF12 was too big of a project for a guy like me. This U47 was my first mic build ever, and I decided that the EF800 was a "safer" choice considering the Pearlman, Wunder GT, Oliver's schematic, and other builds I've seen online all use it. It's also cheaper than the EF14 or EF12, and I read that a 47 clone w/ EF800 supposedly fared well against a real U47 in a shootout. I figured that the EF800 being the glass tube descendent of the VF14 was good enough for me.


Does anyone know where I can buy tested EF800 tubes? To recap, I started this project with 2 EF800 tubes. One of them you can hear in my samples. The other had a very different frequency response, but was also much noisier. I don't know if the sound difference was a result of tube age/use/condition, or if these EF800 tubes vary a lot. If anyone has any info, that would be great. Being able to try a tube with a similar freq response as the noisy tube, but without the noise, would be very interesting.

 

[maq3396]

I'm sure there are a number of vendors for that tube but Christian Whitmore at [email protected] is very meticulous about ensuring the tubes are of the best quality

 

[Aaronrash]

I actually already spoke with Christian about this. He said he doesn't test his EF800 stock, he said most of them sound good and he would feel comfortable selling them as is.

 

[Aaronrash]

So Mello,

I have a couple questions for you.

1.) did you end up changing anything on the power supply besides switching the wires around like Robert instructed?

2.) did you use the pre-sent parts that Oliver sent you or did you deviate and choose different values etc... I read earlier in this thread that the parts sent do not match the schematic so I was just wondering if I need to buy other components. I will probably do my build without pattern switching (cardioid only).

Upon further reading it looks like using the EF12 is just gonna be too hard for me and I need a working mic to record vocals with. I'll save for the Flea but in the meantime would love to build the exact mic you just built. It really sounds awesome and I'm thankful for this thread. I just built 2 EZ 1073s so this mic should be a good match.

 

[Melodeath00]

I'm sure there are a number of vendors for that tube but Christian Whitmore at [email protected] is very meticulous about ensuring the tubes are of the best quality

I actually already spoke with Christian about this. He said he doesn't test his EF800 stock, he said most of them sound good and he would feel comfortable selling them as is.

Yes, this is exactly why I asked. I see "low-noise tested" EF800s on ebay, but I'm a bit wary about buying tubes on ebay. I may just buy from Christian anyway, but I would hate to spend $35 or whatever they are on a tube that ends up being noisy.

So Mello,

I have a couple questions for you.

1.) did you end up changing anything on the power supply besides switching the wires around like Robert instructed?

2.) did you use the pre-sent parts that Oliver sent you or did you deviate and choose different values etc... I read earlier in this thread that the parts sent do not match the schematic so I was just wondering if I need to buy other components. I will probably do my build without pattern switching (cardioid only).

Upon further reading it looks like using the EF12 is just gonna be too hard for me and I need a working mic to record vocals with. I'll save for the Flea but in the meantime would love to build the exact mic you just built. It really sounds awesome and I'm thankful for this thread. I just built 2 EZ 1073s so this mic should be a good match.

1) I did not change anything in the PSU other than the wiring on the Binder connector. The PSU shoots out the correct voltages, just not on the pins you expect. I also had to reverse the hot and cold wires for the audio path to get the right polarity.

2) I used Oliver's parts, although I had to go buy one resistor from Radioshack that was missing from my baggy of parts. Oliver's parts work with the PSU he sends you. His schematic on his website is designed for a PSU with a different voltage (105V I think).

Don't let me discourage you about the EF12; I just don't know much about biasing tubes, and there seemed to be much less info online about the EF12 than the EF800 and EF14. Then again, maybe you read that entire thread and came to this conclusion.

I am happy with how my mic sounds, although I am hoping a different EF800 can get me a little more upper midrange.

 

[o3misha]

I am happy with how my mic sounds, although I am hoping a different EF800 can get me a little more upper midrange.

EF12k tube is the best for U47, IMO (if you have not got good VF14M, of course). It was produced specially for microphone and preamp usage. It is  more quiet than any tube from Telefunken steel tube's family. Thats why Flea and mr.Wagner use EF12 for  theirs microphones.EF12k has very sweet upper midrange and  silky hi end. But you can not use Oliver's PSU for that tube,  because of different biasing method.

 

[Aaronrash]

Christian also told me if people are selling "tested EF800" tubes they are most likely lying. I'm not sure why but he was saying these are very complex to test. I'm not sure why but you could always send him an email. Luckily they're not very expensive.

I think the midrange on your build sounds really good. Much thicker midrange than the ADK, this is why I chose your mic as sounding better btw... It had that extra bite without the harsh high end. The high end on the ADK was very nice too but lacking the mid push of the 47.

I read the entire thread about the EF12 and people were talking about a ton of problems of why it can't be done easily. But upon further investigation it looks like the heater voltage on the EF12 is the same as the EF800. Oliver gave me a number to contact him when I'm ready to build so I'll ask him about it and see. Either way the EF800 or EF12 will get you a 47ish vibe without a doubt IMO

I think as long as I go with the BV8 transformer, Thiersch M7 capsule, U47 body/grill and any nice tube the mic will have a sonic sound of a 47. I'm sure the VF14 makes a difference but I'm not sure if $2000 on a tube justifies that. Like all things audio I've learned over the years is people over hype things, especially a U47 and the tubes inside it. The Flea smashed the vintage 47 IMO and that's with a EF12. I'm gonna rent a vintage 47 when I finish my build just to compare the two for piece of mind of course.

 

[AusTex64]

Hi Aaron,

My first build was Oliver's U47 kit, and I'm grateful for that. Everything came with it, even the tube. I found the supplied components produced a mic that sounds great. FYI Oliver uses many of the exact same parts in the Lucas mics. Look at pics online of the Lucas CS4, you'll see the same coupling caps and other parts. He also can supply the Theirsch capsule without having to import it yourself from Germany. Search for the CS4 schematic, it's on the Lucas website. This is much closer to the mic you'll actually be building. Oliver is a super guy, but way overworked. He really needs to change out the U47 alt tube schematic to mirror what he's shipping, I'll mention it to him again. Once you get the kit built, you can always go back and experiment with fancy caps, different tubes, etc. If you haven't built a mic before, the AMI kit sure makes it a hell of a lot easier.

Robert

 

[Melodeath00]

Christian also told me if people are selling "tested EF800" tubes they are most likely lying. I'm not sure why but he was saying these are very complex to test. I'm not sure why but you could always send him an email. Luckily they're not very expensive.

I think the midrange on your build sounds really good. Much thicker midrange than the ADK, this is why I chose your mic as sounding better btw... It had that extra bite without the harsh high end. The high end on the ADK was very nice too but lacking the mid push of the 47.

I read the entire thread about the EF12 and people were talking about a ton of problems of why it can't be done easily. But upon further investigation it looks like the heater voltage on the EF12 is the same as the EF800. Oliver gave me a number to contact him when I'm ready to build so I'll ask him about it and see. Either way the EF800 or EF12 will get you a 47ish vibe without a doubt IMO

I think as long as I go with the BV8 transformer, Thiersch M7 capsule, U47 body/grill and any nice tube the mic will have a sonic sound of a 47. I'm sure the VF14 makes a difference but I'm not sure if $2000 on a tube justifies that. Like all things audio I've learned over the years is people over hype things, especially a U47 and the tubes inside it. The Flea smashed the vintage 47 IMO and that's with a EF12. I'm gonna rent a vintage 47 when I finish my build just to compare the two for piece of mind of course.

I read through the EF12 thread now, and it didn't seem that hard. I think what happened is soapfoot got advice to run the EF12 out of its ordinary range, which caused an issue with the PSU he designed. That was the reason he switched to EF800. I could be wrong, but maybe an EF12 build is feasible. Actually, I realized I have a conversion PDF for EF12, but I don't know how you would do a PSU for it.

I used to think the tube didn't really matter. This was because I was told by sources who know more than I do that tube type doesn't really matter. Maybe they meant as long as the circuit itself was designed around it. Either way, I found it to not really be true once I built this mic, as even my two EF800 tubes had very different frequency responses. Granted, maybe one of them was so different due to age/use?

Hi Aaron,

My first build was Oliver's U47 kit, and I'm grateful for that. Everything came with it, even the tube. I found the supplied components produced a mic that sounds great. FYI Oliver uses many of the exact same parts in the Lucas mics. Look at pics online of the Lucas CS4, you'll see the same coupling caps and other parts. He also can supply the Theirsch capsule without having to import it yourself from Germany. Search for the CS4 schematic, it's on the Lucas website. This is much closer to the mic you'll actually be building. Oliver is a super guy, but way overworked. He really needs to change out the U47 alt tube schematic to mirror what he's shipping, I'll mention it to him again. Once you get the kit built, you can always go back and experiment with fancy caps, different tubes, etc. If you haven't built a mic before, the AMI kit sure makes it a hell of a lot easier.

Robert

Hi Robert, do you happen to have that CS-4 schematic saved? I can only see a small, blurry image on google, and when I click it for full size, I get a 404 error. Maybe the Lucas forum is just down right now, but I'd love to see it.

 

[melodeath]

Regarding EF800 age/use, check this out. It's a comparison of my two EF800 tubes.

I did one recording with the "good," quiet tube in the 47 versus my Manley Reference Cardioid on voice. I used CurveEQ to analyze the frequency response and "apply" the 47 curve to the Manley, so it show the freq response difference. As you can see, the 47 has about 1 to 2dB more energy from the sub bass all the way up to 3k or 4kHz, and then the Manley has a lot more top end.

The graph below that is the same two mics against each other, also on voice, but probably a day or so later, after I had tried to noisy tube, and then put the good tube back in. You can see it follows the same pattern - from 60Hz all the way to 4kHz, there's about 2dB more energy. I think this proves that the influence of my particular spot in the room doesn't have much affect on this basic comparison of frequency response.

The third graph is a comparison of the 47 with the noisy EF800 to the Manley. You can see here that between 3k and 6k, the 47 has more energy, and less energy between 700Hz and 3kHz. It's just much different in the mids and upper mids compared to the other EF800. A similar rise in the treble of the Manley is apparent, although this EF800 appears to be even darker. Again, this tube is unusable in the mic - it's too noisy. It's not insanely noisy, but it's noticeably more noisy than the Manley, whereas the other EF800 is not.

Do you think I'm being too unscientific, or does this basically show the different responses of the two EF800 tubes? I could do a more scientific test with pink noise or volume sweeps, but it seems pointless since that third graph is with an unusable, noisy tube anyway.

I found it fascinating.