DiY AMI U47

[Pip]

Wow that thing looks crazy haha. I just checked ebay and they're still way out of my league. This is baby's first soldering iron haha

It's probably between the $40 WLC100 and the $90 WES51 Analog. Just depends on if people think I need the temperature control or not.

So the local RadioShack has some 62/36 solder at 0.015". Is that too thin in your experience? I was planning to get some 63/37 at 0.032, but it's expensive and a huge 1 lb spool, which I don't need. Thanks!

Its not that you need a really expensive tool. It's you need the right tool. Not trying to come off elitist or putdownish. These are not expensive ones by any means. They are just the right tool for working with the components you encounter when doing this kind of work. The chords are much more supple so you are not fighting them all the time and they are lighter as well. I have had my Weller for 25yrs with zero failures.

I would say this if you get a non temp adjusting iron start with a 25 watt, as a 40 watt unadjustable is a little rough going. Solder is just about what size you want to work with and make sure it is rosincore. Sadly again good solder is not a oh by the way I need some solder, solder. I use silver solder because it is good for this kind of work and when it oxidises it still conducts as well. That stuff is pricey. I would also suggest some solderwick and a desoldering tool.

If you want to enjoy this journey get into some comfy gear. It's like trying to practice on an instrument with bad action.

Lastly this build is a real commitment to qualitative realities the more quality you commit to in component choice the more quality you get out of it!

Come on in the waters fine.

 

[Melodeath00]

Wow that thing looks crazy haha. I just checked ebay and they're still way out of my league. This is baby's first soldering iron haha

It's probably between the $40 WLC100 and the $90 WES51 Analog. Just depends on if people think I need the temperature control or not.

So the local RadioShack has some 62/36 solder at 0.015". Is that too thin in your experience? I was planning to get some 63/37 at 0.032, but it's expensive and a huge 1 lb spool, which I don't need. Thanks!

Its not that you need a really expensive tool. It's you need the right tool. Not trying to come off elitist or putdownish. These are not expensive ones by any means. They are just the right tool for working with the components you encounter when doing this kind of work. The chords are much more supple so you are not fighting them all the time and they are lighter as well. I have had my Weller for 25yrs with zero failures.

I would say this if you get a non temp adjusting iron start with a 25 watt, as a 40 watt unadjustable is a little rough going. Solder is just about what size you want to work with and make sure it is rosincore. Sadly again good solder is not a oh by the way I need some solder, solder. I use silver solder because it is good for this kind of work and when it oxidises it still conducts as well. That stuff is pricey. I would also suggest some solderwick and a desoldering tool.

If you want to enjoy this journey get into some comfey gear. It's like trying to practice on an instrument with bad action.

Lastly this build is a real commitment to qualitative realities the more quality you commit to in component choice the more quality you get out of it!

Come on in the waters fine.

No, it's not putdown-ish or elitist. But we're talking about a $600 soldering iron here! Or maybe we're talking about different things? I'm sure it works great, but I think it's probably just excessive for my needs. And it's way too much money for me currently. I already committed to quality by buying the best capsule, transformer, and mic body possible, so I think I'm already on track with what you're talking about.

Thanks for the advice about the iron. I think I may just get the WES51 Analog so I have the temperature control. It sounds somewhat useful and I should be able to keep it for years and years. I don't have much of any soldering experience, that's why I was asking about solder size to see what other people here like to work with in their experience. My original plan was 63/37 at .032" based on some recommendations here.

 

[Pip]

Yes I agree $600.00 is a lot for someone who is hobbying but I believe my two suggestions topped out at about $150.00. Yes I agree also you have commited to a good build component wise. All I was saying is go the extra yard you will be glad you did. I will go out on a limb and say that anyone who ventures into these forums will find a channel and outlet for any possible OCD issues ;D ;D ;D.

Also since this is your first soldering experience at this level maybe practice on something a little first to build your chops up. I just finished several builds that are offered in this forum one of which IOAUDIOS MK47 and I have been soldering for years. It was challenging at times to maintain a clean concise build that is going to be reliable. Also not to become Captain Daunting but there is a fair amount of machining and fabrication in your future.

Best of luck it is so worth it.

 

[Melodeath00]

Ok guys, slowly acquiring parts still. I have my soldering iron (I got the Weller WES51 Analog), solder, and multimeter now, so it's time to get moving. Really all I'm missing is some hook-up wire, and a cap and some resistors (some of the resistors I got sent are not the right values, and some I cannot measure - these are probably the 1G).

I have what I need to wire up the tube mic cable with the Binder connectors, so I decided to start taking a close look at it. Looking at the schematic, I got a little confused as to whether the 7-pin connector is from the viewpoint of the front or the back. In other words, the side where you plug in the male ends, or is it a view from the back, where I will be soldering? The back of the Binder connector has numbers, so I figured it was probably this numbering system I should use, but before I go to the trouble of soldering up the cable, the only way to be sure is to check the voltages from the PSU.

Pin 4 is supposed to be ground, so I've got my black COM probe on pin 4. Pin 3 is supposed to be putting out 105V, but I'm putting the red probe on it and I'm getting 0V. However, I'm getting 116V on pin 5. That's relatively close, but it's not the right pin. Pin 6 is supposed to put out 5.05V, but I'm getting 47V from the PSU. Am I doing something incorrectly? I didn't expect to be at a roadblock so quickly. I get 0V on all the other pins (except Pin 7 which is supposed to be for polar pattern switching).

Thanks

 

[Pip]

Ok guys, slowly acquiring parts still. I have my soldering iron (I got the Weller WES51 Analog), solder, and multimeter now, so it's time to get moving. Really all I'm missing is some hook-up wire, and a cap and some resistors (some of the resistors I got sent are not the right values, and some I cannot measure - these are probably the 1G).

I have what I need to wire up the tube mic cable with the Binder connectors, so I decided to start taking a close look at it. Looking at the schematic, I got a little confused as to whether the 7-pin connector is from the viewpoint of the front or the back. In other words, the side where you plug in the male ends, or is it a view from the back, where I will be soldering? The back of the Binder connector has numbers, so I figured it was probably this numbering system I should use, but before I go to the trouble of soldering up the cable, the only way to be sure is to check the voltages from the PSU.

Pin 4 is supposed to be ground, so I've got my black COM probe on pin 4. Pin 3 is supposed to be putting out 105V, but I'm putting the red probe on it and I'm getting 0V. However, I'm getting 116V on pin 5. That's relatively close, but it's not the right pin. Pin 6 is supposed to put out 5.05V, but I'm getting 47V from the PSU. Am I doing something incorrectly? I didn't expect to be at a roadblock so quickly. I get 0V on all the other pins (except Pin 7 which is supposed to be for polar pattern switching).

Thanks

All those voltages are without load of mic circuit on them so they are not going to reflect true working values in some instances. Yes the Binder connector numbers are on the inside but that means the pin marked seven is seven. Also Olivers supply is probably wired for U47 original unless you are using remote switching then things get different. Make sure you have right supply from AMI. Olivers remote switching mic schematic has 1=mic out, 2=mic out, 3=105VDC, 4=GROUND, 5=filament supply return, 6= filament voltage 5.05VDC, 7=remote switching connection.

 

[Melodeath00]

All those voltages are without load of mic circuit on them so they are not going to reflect true working values in some instances. Yes the Binder connector numbers are on the inside but that means the pin marked seven is seven. Also Olivers supply is probably wired for U47 original unless you are using remote switching then things get different. Make sure you have right supply from AMI. Olivers remote switching mic schematic has 1=mic out, 2=mic out, 3=105VDC, 4=GROUND, 5=filament supply return, 6= filament voltage 5.05VDC, 7=remote switching connection.

I supposed you are right that it is totally unloaded. Still, I would expect that 116V to be on Pin 3, not 5. Ok, I will use the number system on the back of the Binder connectors and hope it works out. The PSU is from Oliver and it has Remote polarity switching. It should be correct, but I guess we wont know for sure until the mic is built.

The 7-wire cable I received seems to have 2 thicker wires in it. Should I use those two for the filament voltage and filament supply return? or something else?

 

[Pip]

All those voltages are without load of mic circuit on them so they are not going to reflect true working values in some instances. Yes the Binder connector numbers are on the inside but that means the pin marked seven is seven. Also Olivers supply is probably wired for U47 original unless you are using remote switching then things get different. Make sure you have right supply from AMI. Olivers remote switching mic schematic has 1=mic out, 2=mic out, 3=105VDC, 4=GROUND, 5=filament supply return, 6= filament voltage 5.05VDC, 7=remote switching connection.

I supposed you are right that it is totally unloaded. Still, I would expect that 116V to be on Pin 3, not 5. Ok, I will use the number system on the back of the Binder connectors and hope it works out. The PSU is from Oliver and it has Remote polarity switching. It should be correct, but I guess we wont know for sure until the mic is built.

The 7-wire cable I received seems to have 2 thicker wires in it. Should I use those two for the filament voltage and filament supply return? or something else?

http://www.groupdiy.com/index.php?topic=41379.msg662630#msg662630

 

[Melodeath00]

All those voltages are without load of mic circuit on them so they are not going to reflect true working values in some instances. Yes the Binder connector numbers are on the inside but that means the pin marked seven is seven. Also Olivers supply is probably wired for U47 original unless you are using remote switching then things get different. Make sure you have right supply from AMI. Olivers remote switching mic schematic has 1=mic out, 2=mic out, 3=105VDC, 4=GROUND, 5=filament supply return, 6= filament voltage 5.05VDC, 7=remote switching connection.

I supposed you are right that it is totally unloaded. Still, I would expect that 116V to be on Pin 3, not 5. Ok, I will use the number system on the back of the Binder connectors and hope it works out. The PSU is from Oliver and it has Remote polarity switching. It should be correct, but I guess we wont know for sure until the mic is built.

The 7-wire cable I received seems to have 2 thicker wires in it. Should I use those two for the filament voltage and filament supply return? or something else?

http://www.groupdiy.com/index.php?topic=41379.msg662630#msg662630

Hi Pip, thanks for that link! However, it doesn't seem to apply directly because it advises to cut the grey wire, and I need all 7 connectors according to the schematic. I'm also a bit confused as to whether the 0V filament return is sometimes referred to as a sort of "ground," or if they mean the blue wire should go to Pin 4 Ground. This is also going to come up again when dealing with Pin 6 shield of the tube, which I have read can be hooked to ground, and I don't know if they mean ground of the circuit, or the Pin 5 0V filament return.

I already wired up the male end of my Binder cable, but considering it was my first soldering experience (and 7 small pins!) it was a nightmare and doesn't look too pretty. I'll probably have to redo it.

 

[Melodeath00]

Sorry to double post, but I have come across some more info, which has lead to another question. So I have 2 main questions.

1) The shielding (braided strands of copper) of the cable - I was planning to simply connect this to a screw inside of the Binder connector sleeve. Am I also supposed to connect it to Pin 4 ground? I have read this posted by Neumann and Klaus, but I'm not sure if I'm misunderstanding.

2) Is the 0V coming from pin 5 of the tube considered "ground" even though there is a separate connection for all other ground connections and it goes to Pin 4 of the Binder? Looking at the G7 mic schematic, I see the shield of the EF86 is connected to the 0V as opposed to ground of the circuit.

I need to know if I connect EF800 Pin 6 shield to circuit ground, or to 0V pin 5 of the tube. I also need to know if I should use the thick blue wire in the 7-wire cable for circuit ground connection (Pin 4 of Binder) or for 0V from tube (Pin 5 of Binder). I'm getting pretty confused, unfortunately.

 

[Melodeath00]

I finished wiring up the Gotham/Binder cable. I hope the rest of the mic is easier, because soldering those 7 pins was not easy for a newbie. I also received my hookup wire. Just waiting on my K47 mount now, and some mouser parts that I'm about to order.

During the process of wiring up the cable, I realized my new $35 Mastech multimeter is defective. I will be returning it, but before I order another of the same and hope it's not defective, does anyone have any multimeter suggestions? I know Fluke is a respected brand, but they appear to be about $130 on Amazon and don't seem to have the ability to measure capacitance, which the Mastech could. I'm willing to spend more than $35, but $130 seems like more than I need. Thanks!

 

[Pip]

I finished wiring up the Gotham/Binder cable. I hope the rest of the mic is easier, because soldering those 7 pins was not easy for a newbie. I also received my hookup wire. Just waiting on my K47 mount now, and some mouser parts that I'm about to order.

During the process of wiring up the cable, I realized my new $35 Mastech multimeter is defective. I will be returning it, but before I order another of the same and hope it's not defective, does anyone have any multimeter suggestions? I know Fluke is a respected brand, but they appear to be about $130 on Amazon and don't seem to have the ability to measure capacitance, which the Mastech could. I'm willing to spend more than $35, but $130 seems like more than I need. Thanks!

http://www.testequipmentdepot.com/ideal/multimeters/61-312.htm

 

[Pip]

Hey MDeath how is it going? Would like some progress reports as I too will walk this path soon.

 

[Melodeath00]

I got my new multimeter, and my cable is working correctly based on a continuity test. Unfortunately, that's as far as I've gotten. I still need to order most of the resistors and a cap in order to start the build. I got so hung up on all the different types and options I could buy, that I sort of fell off the "train," and lost some enthusiasm. But I WILL finish this mic ASAP.

I also received my K47 mount, so some circuit parts is truly all I still need.

 

[Pip]

I got my new multimeter, and my cable is working correctly based on a continuity test. Unfortunately, that's as far as I've gotten. I still need to order most of the resistors and a cap in order to start the build. I got so hung up on all the different types and options I could buy, that I sort of fell off the "train," and lost some enthusiasm. But I WILL finish this mic ASAP.

I also received my K47 mount, so some circuit parts is truly all I still need.

If you are still looking for C1 and C3 of the build I have some 1UF PIO caps that might work for you. PM me.

 

[AusTex64]

Hello MDeath,

I just finished an AMI U47 kit based on Oliver's alternate tube with remote pattern switching schematic. My Dad taught me how to solder at about age 10, and I've been working on guitars, amps, audio and lighting equipment since. Building super high impedance mics are another animal. Things I would have never cared about or noticed on a guitar amp make a big difference on a device as sensitive as a mic. So, if you just started soldering, I suggest practicing on something besides the mic before you even start putting it together.

Here are some things I learned the hard way:

1. The AMI U47 alternate tube with remote pattern switching schematic is not correct. Oliver is a SUPER nice guy and has been very helpful with me, and this is IN NO WAY meant to throw him under the bus. But you need to be aware. Look at the UM75/92/92.1 mod schematic located here http://www.tab-funkenwerk.com/id71.html The voltage divider layout is what you're gonna want to use with that PSU. Also, unless he has changed the PSU, you're gonna have to move a couple of wires around on the Binder connector in the PSU to make it work right. I'm sure he'll get around to updating the drawings on his site soon (we discussed it), but I get the impression this poor guy works way too much and has too many guys like us asking him questions!

2. You'll need Teflon jacket hookup wire inside the mic. A lot of people (including Oliver I think) use silver coated copper wire with Teflon jacket.  I looked at a great build thread written by Brad here http://www.offsetguitars.com/forums//viewtopic.php?f=27&t=42991&sid=16c2f9742629e25934a59796b1268cf9 He used solid silver with PTFE coating for
the audio connections. I did as well and was happy with the results. The high impedance and sensitivity of these mics benefit from wire like this.

3. I spent a week figuring out the component layout and drew it 4 times before I got it right. You'll find lots of schematics and discussions, but I could not find a published layout for this mic anywhere. Not like a guitar amp or 1176 kit where you get a schematic and layout of components.

4. With 1G ohm and higher impedances in the mic, skin oil will act as a conductor if you touch certain components with bare hands. I assembled the upper deck and capsule wearing nitrile gloves my nurse wife got for me. Even then, I had to go back and clean everything again with alcohol to get rid of noises. Ditto for the capsule - it's really easy to touch it, graze it etc with your hand. I did it to a Thierch M7 PVC capsule, got skin oil on it. I cannot emphasize enough how careful you have to be with the items on the upper deck.

5. Wrap blue tape around the head cover where the screws go in, and on the mic body below. Odds are you'll have the mic apart a few times before everything is right if this is your first build of anything. This will help keep the chrome from getting scratched.

6. Don't over tighten any screws on the acrylic upper deck, it's easy to crack. Believe me...

7. Drill the holes the EXACT right size for the posts used to mount the resistors and cap on the upper deck. Do not force them into the holes, or the deck will crack. Also, don't use too much heat on the iron while soldering to these, or you'll deform the acrylic with heat.

8. Use the exact size ultra tiny screwdriver for attaching the capsule to the holder. And be ultra careful and slow, do not rush ANYTHING when working with the capsule. It would be very easy for the screwdriver to slip off and whack the capsule diaphragm.

Watch this video of a U87 being built, especially assembly. Note the tools, work surface, etc. http://www.youtube.com/watch?v=jCO95wBAIt0&feature=youtube_gdata_player

Hope I didn't scare ya too bad! But I'm not gonna lie - you picked a doozy for a first electronic project. I looked at the schematic and thought "this doesn't look too complicated", but there really is an art to building tube mics correctly - cleanly, low circuit noise, low tube noise, no buzzes or crackles, etc. It's an unbelievably sensitive circuit.

Best of luck on your build, let us know how it goes.

 

[micaddict]

Quite an opening post.

Welcome and thanks.

 

[AusTex64]

Thanks MicAddict. I'm a long time lurker. Figured it was time to give something back....

 

[AusTex64]

I'm gonna add info as I dig it up to this thread with the hope it will help other builders....

I bought my 22AWG FEP jacketed solid silver wire from Homegrown Audio. Here is a link: http://www.homegrownaudio.com/22-awg-silver-wire-fep-solid-core-speaker-wire/

These people have excellent customer service. I wanted this wire quickly and they came through, shipped it same day and I ordered late in the day.

 

[0dbfs]

Just my thoughts but if you're going to buy a test capsule / trafo, why not go ahead and make it an M7 style capsule and make a second mic out of them later.



Cheers,
j

 

[Melodeath00]

Hello MDeath,

I just finished an AMI U47 kit based on Oliver's alternate tube with remote pattern switching schematic. My Dad taught me how to solder at about age 10, and I've been working on guitars, amps, audio and lighting equipment since. Building super high impedance mics are another animal. Things I would have never cared about or noticed on a guitar amp make a big difference on a device as sensitive as a mic. So, if you just started soldering, I suggest practicing on something besides the mic before you even start putting it together.

Here are some things I learned the hard way:

1. The AMI U47 alternate tube with remote pattern switching schematic is not correct. Oliver is a SUPER nice guy and has been very helpful with me, and this is IN NO WAY meant to throw him under the bus. But you need to be aware. Look at the UM75/92/92.1 mod schematic located here http://www.tab-funkenwerk.com/id71.html The voltage divider layout is what you're gonna want to use with that PSU. Also, unless he has changed the PSU, you're gonna have to move a couple of wires around on the Binder connector in the PSU to make it work right. I'm sure he'll get around to updating the drawings on his site soon (we discussed it), but I get the impression this poor guy works way too much and has too many guys like us asking him questions!

2. You'll need Teflon jacket hookup wire inside the mic. A lot of people (including Oliver I think) use silver coated copper wire with Teflon jacket.  I looked at a great build thread written by Brad here http://www.offsetguitars.com/forums//viewtopic.php?f=27&t=42991&sid=16c2f9742629e25934a59796b1268cf9 He used solid silver with PTFE coating for
the audio connections. I did as well and was happy with the results. The high impedance and sensitivity of these mics benefit from wire like this.

3. I spent a week figuring out the component layout and drew it 4 times before I got it right. You'll find lots of schematics and discussions, but I could not find a published layout for this mic anywhere. Not like a guitar amp or 1176 kit where you get a schematic and layout of components.

4. With 1G ohm and higher impedances in the mic, skin oil will act as a conductor if you touch certain components with bare hands. I assembled the upper deck and capsule wearing nitrile gloves my nurse wife got for me. Even then, I had to go back and clean everything again with alcohol to get rid of noises. Ditto for the capsule - it's really easy to touch it, graze it etc with your hand. I did it to a Thierch M7 PVC capsule, got skin oil on it. I cannot emphasize enough how careful you have to be with the items on the upper deck.

5. Wrap blue tape around the head cover where the screws go in, and on the mic body below. Odds are you'll have the mic apart a few times before everything is right if this is your first build of anything. This will help keep the chrome from getting scratched.

6. Don't over tighten any screws on the acrylic upper deck, it's easy to crack. Believe me...

7. Drill the holes the EXACT right size for the posts used to mount the resistors and cap on the upper deck. Do not force them into the holes, or the deck will crack. Also, don't use too much heat on the iron while soldering to these, or you'll deform the acrylic with heat.

8. Use the exact size ultra tiny screwdriver for attaching the capsule to the holder. And be ultra careful and slow, do not rush ANYTHING when working with the capsule. It would be very easy for the screwdriver to slip off and whack the capsule diaphragm.

Watch this video of a U87 being built, especially assembly. Note the tools, work surface, etc. http://www.youtube.com/watch?v=jCO95wBAIt0&feature=youtube_gdata_player

Hope I didn't scare ya too bad! But I'm not gonna lie - you picked a doozy for a first electronic project. I looked at the schematic and thought "this doesn't look too complicated", but there really is an art to building tube mics correctly - cleanly, low circuit noise, low tube noise, no buzzes or crackles, etc. It's an unbelievably sensitive circuit.

Best of luck on your build, let us know how it goes.

Thank you so much for the reply. I'm going to address your points by the numbers you gave, as I feel that would be simplest...

1) Uh oh... Can you recall what exactly you did inside of the PSU? This was one of the reasons I bought the AMI PSU - I didn't want to have to mess with it at all for a first build. I wonder if this is why I was getting strange measurements at the PSU on pin 5 and 6, with 116V and 47V, respectively? I'm very confused now... I thought that PSU was made for the Alt-tube U47, but that UM92 Mod is feeding 120V on Pin 5 as opposed to 105V on Pin 3 like in the U47 schematic.

2) Thanks. I bought some silver teflon hook-up wire from Chunger. It's for his C12 kit, but I bought it for my U47. Did solid core work ok for you? Most people recommend stranded.

3) Do you have a picture of your component layout? That is something I haven't figured out yet, and I would be extremely grateful to see yours!

4) Thanks for the tip. I cannot measure 4 of the resistors that Oliver sent me, so I have a feeling they are 1G. (My multimeter only goes up to 400M or so I think). But I will definitely do my best to clean the section with alcohol. Also, I bought a cheap capsule to get a feel for handling a capsule in a build and testing the circuit before I even open my Beesneez K7.

7) Do you know what size hole I need to drill? I didn't even think about that. I'm going to have to borrow a drill.

Just my thoughts but if you're going to buy a test capsule / trafo, why not go ahead and make it an M7 style capsule and make a second mic out of them later.



Cheers,
j

That's a good idea, but here's my take on it: There aren't any M7 capsules cheap enough that I would want to leave in a mic that I could also use for testing. I like to go all out component-wise, so if I ever get an M7, it's going to be a Thiersch or a Beesneez, and neither of those are cheap enough to be considered a good "testing" capsule. I got a K67 for $15 instead , which I can also use to test/compare when/if I build the DU-67.