Jumping In With Both Feet. DIY Ribbon Planning.

[shoggoth80]

So, I've watched several videos of DIY builds for ribbon mics.
I've got a donor body that I want to work with. It's not a ribbon body, but a cheap cheap condenser.
Seems like the hardest bit will be building the motor frame.
I've got the donor en route, a pack of 2.4" ND magnets, just ordered some 1.8 micron foil, and a corrugating tool.
I'm mostly gathering the materials, hoping to have all the components within a month. I read the RCA 44 used a 4.7mm wide ribbon, and about 2.4" long, that was 1.8 microns. I'm going to aim for 3/16" wide, which is close.

I haven't made up my mind on a transformer. Edcor is tempting, but Geistnote has an in house unit that is affordable, and supposedly sounds close to the RMX1.
I know people seem to like Lundahl, but that's a little more than I am looking to spend, unless it really is worth it.

Any thoughts on transformers?

 

[shoggoth80]

A lot of folks checked out the thread, but no replies. Lol. Guess I'm gonna have to take a bunch of pics as this project comes along.

I decided on a FAB 1:38 "Metron" trans. I watched a video where a guy used a FAB XL to update an older RCA "paintbrush." The mic model name escapes me. Sounded nice though. Price was pretty agreeable, data sheet included so that should take out extra measurements and guesswork.

The magnets have been delivered, though not picked up. The donor body should be here by the end of the week. The ribbon foul and tool is on the way, and I ordered the trans last night.

Need to get material for the motor frame, and copper tape.

I know it might not be exciting to everyone, and this thread will definitely need pics... but I'm pretty stoked.

 

[Steenamaroo]

Hey! Only a couple of people plus you and I have checked this post.
The rest of the 'views' are crawlers/bots.

I don't have any transformer advice but I'm always interested in a DIY project! Looking forward to seeing how it goes.

 

[shoggoth80]

Lol. I've been doing a LOT of reading and video watching the last couple weeks. Deciding on the trans was the last major bit. It'll be a couple weeks before I can start in earnest, but by that point, I'll have all the materials together.

Hey, one other enthusiastic member ain't bad.

 

[shoggoth80]

Alright. Picked up the pieces that came in. The magnets are thinner than expected, but are pretty strong, so shouldn't be an issue. Thinking I might double up. Don't know if that will cause any issues, but I don't think it will. I nabbed a BM800 for the donor shell... and it is the cheapest thing I've ever seen. Lol. Good thing I just want the outsides. The data sheet is something else. Lol.

 

[rob aylestone]

I saw the topic, but didn't read it because I didn't realise it was about building a ribbon mic. I saw ribbon planning, and didn't know what planning would be involving ribbons. Now after reading I've realised you're building a ribbon. Sorry I didn't make the link. It's an interesting project - but I'm not sure enough of us have experience on actually building mics. I've never ever done it. I have mended quite a few, so the process wouldn't worry me - but transformers? To me they are just components, and I wouldn't know anything about brands. I know one 'brand' SOWTER - they have made transformers in England for ever, but Americans prefer their brands. Now of course we have Chinese unbranded ones. I guess you need to try swapping them to see? It's kind of a hobby in itself. Keep us updated.

 

[shoggoth80]

Well I didn't want to call it a build yet, since I'm mostly gathering components, and was seeking ideas. Like I said though, I've watched and read a bit on DIY builds, and looked up some general specs, and jumped. I have enough magnets to do two mics. I should end up with enough foil for more than that. Using the cheap BM800 as a donor body is strictly
cosmetics. If it works like I hope, I want to try and make something classic looking, which will take a lot more elbow grease to come up with. I also kind of want to use mild steel for the ribbon motor frame like Royer does to beef up the magnetic field. Lots of guys make them with plastic, and I may do that round one. There's a fair bit of enthusiasm, a familiarity with hand tools, and little actual technical knowledge... but there's probably worse things than mimicking the specs for models and sounds you like.

 

[DM60]

Back to what Rob stated, you are moving into an area I know nothing about, but I am keeping an eye on the topic. Mics are so much a dark art.

 

[shoggoth80]

Attempt at a basic template for the motor frame.
Will see if it translates over into something usable in the near future.

 

[shoggoth80]

Ribbon foil, crimping tool are in my mailbox. Transformer is in hand. Copper tape en route. Got the Austin DIY pdf, and I've found the information in there worth the $10 asking price.
I'm likely to gut the donor body on lunch today.

 

[shoggoth80]

Crimper/corrugating tool, foil, copper tape, and epoxy in hand.
Moved at the end of last month, so I haven't set up a work space. Need to get the acrylic or whatever material to construct the motor cage.

 

[shoggoth80]

I found a little e book and YouTube series for this sort of thing. It even has a parts list and what not. $10 purchase. Now, I've been super lazy and haven't gotten around to piecing anything together, but I've got all the bits but the motor frame. I need to source the acrylic pieces for that. Life got in the way. Lol.

 

[rob aylestone]

A link to a legal site - nothing to do with recording - copied and pasted from all sorts of forums.

 

[shoggoth80]

Aside from the unrelated post... my coworker has a 3D printer, and we're gonna try a 3D printed frame for the ribbon motor. This is a super slow project, but it's step forward.

 

[shoggoth80]

Frame is printed. Broke some of my magnets. Replacement set ordered. Lol. I know there's plenty of cautionary statements regarding ND magnets, but yeah... they're strong, and brittle. Lol.

I'll try and get pics of some stuff tonight.

 

[TalismanRich]

Not to diminish your project, but I always wonder about these DIY microphones.

My biggest concern would be how to know if the mic is anywhere close to being in spec. Do you have a way of measuring the response, distortion, noise level? It's one thing to assemble some parts to make something. You can build a 5E3 amp, for instance and test it using very basic test equipment. If I'm building a race car, I can test it for acceleration, etc at a track. How do you test the mic?

For me, just listening to it is NOT going to tell me if things are working the way they should. You have folks like AudioTechnica, Rode, MXL, etc who obviously have the equipment to test their products. It might test very close to a Nuemann, yet they get blasted as putting out cheap crap. Then people will change out capsules and parts and declare that their mod makes it the next best thing to a vintage U47.

From the standpoint of making the mic and actually getting sound out of it, great. Do you know the resonance of the ribbon? How do you compensate for the response? How do you measure tension on the ribbon in the first place?

... just curious.

I'll be interested in hearing your results.

 

[shoggoth80]

Those are some very good questions that I don't have exact answers for. This is just for grins. I wanted to try something new, and if I succeed, awesome, and I have a new gadget to play with.

I've seen the DIY folks use a clothespin to tension, and I've watched one where a guy used a ball of e tape. Not very scientific I know. I need to look up a bit more on that. On the other hand, I have enough material to screw up a time or two on the ribbon.

As far as measuring response, I could look up how to push a sine wave through it, and possibly adjust tension for tailoring the response. I'm still gathering stuff, and that includes info.

The foil I have is 1.8 micron thick, which I picked because I read that's what RCA used in the 44, and I thought it would be neat to try and mimic that, with as much as that model is sought after.

I picked a transformer that sounded like it would be decent between price, product reviews, and description. If by some means this project fails miserably, I can transformer swap a mic, or maybe use it as a step up project or something. So even if it doesn't work, it's not a massive loss. Lol.

 

[TalismanRich]

Like I said, I'm curious. I've watched a lot of auto racing, and I've heard guys make tweaks to a car and come back to say "yeah, that feels smoother and a lot faster". Then they look at the stopwatch and find out they're 1.5 seconds slower per lap. Turns out it feels more in control because they are slower, so not hitting the edge of control.

"Subjective" sounds great, but it can be fooled! Measurements don't lie, they may not tell all, but they at least give you a way to documents results.

 

[ecc83]

One way to check frequency response would be to buy a cheap reference mic like the Behringer and set it up alongside the ribbon and blast the lot with white or pink noise, recording the result. Stuff that through Right Mark RTA and you will get a plot of both mics. Neither is likely to be flat but you will be able to see how much the ribbon deviates from a nominally flat microphone.

Sound QUALITY is a completely different matter!

Dave.

 

[shoggoth80]

Mock up for the frame and magnets. I want to get a better spacer, and of course epoxy them in place. They fit the 3D printed frame pretty nicely.