Enchilada's Mic Builds - U47 /U47FET Comparison!!!

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Enchilada

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Latest thing:
See my most recent post for a comparison between my U47 with a Beeznees M7 and my U47FET with a Cathedral Pipes M7!!!
http://www.groupdiy.com/index.php?topic=50171.msg681289#msg681289

Also ordered one an M7 capsule from the white market. Been waiting for ages for these to become available and can't wait for it to arrive. When it does, I'll build identical circuits and shoot it out against the RK47 and the Beeznees M7  8)

I'm planning on building a few mics over the next couple of months so I thought I might start documenting them in a thread as opposed to my usual style of starting a new thread for each build. Next up I'll be building a U47 using Oliver Archut's schematic using an Alctron GT-2B as a donor and I'll try do document that build better as opposed to just posting the end result. At the moment, the mic is working although I haven't recorded anything with it just yet. I'm not much of a singer but I might head out to the studio and record something just to get some feedback on how it's sounding so far.

Here's a pic:
DSC_0004531x800.jpg


Hopefully this thread doesn't annoy people, I always like seeing what others are building so I though I would share what I've been up to.

Ench.
 

letterbeacon

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Enchilada said:
Next up I'll be building a U47 using Oliver Archut's schematic using an Alctron GT-2B as a donor and I'll try do document that build better as opposed to just posting the end result.

I'm thinking of doing this too at some stage -let us know how you get on!
 

Blue Jinn

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Cool. The BV8 is something like 6.5:1 isn't it? The stock circuit specifies a 12:1 or so. How does it sound? (I have one of those BV8's from Dave Thomas as well, was thinking of using it for a G7'sh type without feedback.
 

Enchilada

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Stock is but I think the 6.5:1 works because the output capacitor is 2.2uF as opposed to the original value of 1uF.

That was my understanding, I may be wrong.
 

Enchilada

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Next project: U47 Inspired mic.

I once tried and failed to build a U47 inspired mic using a 5693 tube. I'm going to resurrect the project to see if I can get it sounding nice. I've ordered myself an AMI T47 transformer, a Beez Neez M7 capsule and a couple more tubes for testing (EF12, EF14, EF80 and EF800).

This time, instead of trying to re-invent the wheel, I'll be starting with Oliver's U47 schematic and tweaking it to taste.

I have a different donor body this time. An Alctron GT-2B on which I'll be using longer rails and a new body tube so it will all fit.
 

Enchilada

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Okie dokie, here's some more pics from my Royer build. I'll be testing it out next week with my good old friend Lauren  ;D.

PCB
DSC_0007800x531.jpg


2.2uF polypropylene output cap.
DSC_0009800x531.jpg


AA BV8 style transformer.
DSC_0011800x531.jpg


PSU PCB
DSC_0014800x531.jpg


Don't know if this was the best idea but it worked. Marking out where to cut with my Dremel.
DSC_0020800x531.jpg


Hole cut.
DSC_0021800x531.jpg


PSU Back.
DSC_0022531x800.jpg


PSU Front
DSC_0024531x800.jpg


PSU Inside.
DSC_0025800x531.jpg



I mentioned earlier that I used a 5-pin connector so I didn't have enough pins for remote pattern selection.  I used a voltage divider in a DP3T switch to give me omni, cardioid and figure-8. The switch in on the back of the mic so it's not too bad. I might have to figure out a way to paint the washer and the nut black though because they really stand out on an all black mic.
DSC_0027531x800.jpg
 

Enchilada

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Also as promised, pics of my C12. It's a fairly rough build but it works. I originally built it for a different donor mic so it was transplanted into this Alctron HST-11A because I prefer it looks wise for a C12 style mic. I couldn't drill holes to screw it on because it would have went right through the ground and I couldn't have been bothered re-doing the PCB layout so I just taped it in. Taped in the tube socket too. I might etch a new PCB one day but for now, it works.

This mic has Tim Campbell's CT12 capsule, a Cinemag CM-2480 transformer and a NOS Mullard 6072.

Again, I'll be recording Lauren with this mic next week and I'll upload it to SoundCloud for all to hear.

DSC_0005800x531.jpg
 

micaddict

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Cool!

Hey, that picture above the last reminds me of this one from the Gearslutz forum (MCA SP-1 mods):

SP1.jpg


Both seem to be in the mood.  ;)

In all seriousness now. Thanks for sharing.
 

Blue Jinn

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Can you tell us how you wired the voltage divider for the pattern switching? I have a general idea of how to do that, but curious about yours.

When I get my donor body from Chunger, I'm thinking of doing another Royerish circuit, with 5 pin (as I have a lot of those) except with a full size tube (6AK5 which is supposed to be similar to 5840)

 

Enchilada

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Blue Jinn said:
Can you tell us how you wired the voltage divider for the pattern switching?

No problem, see the attached diagram. In case any noobs a viewing, a resistive divider is where you connect a voltage to two resistors in series and then to ground. If the two resistors are of equal value then the voltage will be halved between the two resistors.

Resistive_divider.png


Here's where I learnt all about dividers http://en.wikipedia.org/wiki/Voltage_divider
 

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Enchilada

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Here's the body I'll be using for my U47 inspired mic, I'll post a better picture later. It started life as an Alctron GT-2B but I've used longer rails and had a body tube machined  ;D ;D ;D

The body is just raw steel for now which I think looks pretty cool but I'll probably end up having it painted. Just not sure what colour. It will have to match the colour of the headbasket and bottom as I wouldn't be painting them. Any suggestions?

I'm still waiting for my tubes, transformer and to pay-off my Beez Neez M7 capsule for this bad boy but because I'm so impatient I think I'll quickly chuck a royer circuit in there.

EDIT: Here's a better photo as promised.

DSC_0002531x800.jpg
 

micaddict

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+1

I've used longer rails and had a body tube machined  ;D ;D ;D

Good lookin' fer sure.

The body is just raw steel for now which I think looks pretty cool but I'll probably end up having it painted.

Do you have to? I mean, would there be another -practical- way to stop it from oxidizing? One that will keep the look pretty much as is?
 

Enchilada

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Not really. The best options are to have it powder coated, prime it with a cold gal primer and then paint it or to have it hot dipped. Hot dipping probably offers the best protection against corrosion but I'm not a big fan of the finish. I've powder coated a mic body before but it's a bit too high gloss for me.

I think I'm going to give it a lick of paint and see how it turns out. worst case scenario I can take to it with a wire brush and try something else.

It does look pretty good in that photo although in person it looks a bit funny because the original painted parts have a slight gold tinge to them so it kind of clashes with the bare steel.
 

Enchilada

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I couldn't help myself. I put a few spare parts into this mic body to get it going. I've used one of Bigugly's Royer PCBs, an Apex 460 transformer, an RK47 capsule and a CK5784 tube. Heater is running at 5.6V and the B+ is sitting at 108.6V (both under load). It's sounding quite good but not amazing. It will be amazing later  :p.

I also tried it with 5840 and 5693 tubes. The 5693 still had a fair 1KHz bump and the 5840 was more aggressive sounding than the 5748. I settled on it because it sounded very smooth overall.
 

HellfireStudios

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Is the body tube steel or stainless steel? Stainless will have chromium on its surface that will make it more difficult to paint/powdercoat. I intend to use a stainless tube for my next mic build, and will have to sand it well to allow the self-etching primer to bond to the surface.

Powder coating that body a Telefunken Buttercream would give it a 251 vibe. Nickle-plating the tube would probably make it resemble the rest of the mic, and look similar the the U-47 you're soon to emulate.

-James-
 

Enchilada

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It was galvanised pipe but when it was machined they took off the gal. Not stainless though. I thought about nickel but there's nobody locally who can do it and I don't want to have to send it away.
 

Dylan W

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Looks awesome. +1 on the buttercream powdercoat, but that's just personal preference.  ;)

Could you post an interior shot? Curious to see how you extended the rails.

Dylan
 

Enchilada

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I kind of improvised when extending the rails. I had two damaged CAD Trion 6000 mics and I used those 4 rails to male 2 longer rails.
 

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