One-Day Ribbon Mic!!!! with pix

[El Fito]

Guess what? Yesterday I made my second ribbon mic. I mean, I didn't just finish it yesterday: I started it and finished it yesterday :shock: bar the trafo, as I didn't have one at hand.

I started the day playing my bandoneon a bit (one of those weird, very noisy acoustic instruments) until my girlfriend's friend arrived and the requisite peace necessary to rehearse had vanished. So I turned my attention to a few bits and bobs I had lying around, including a very attractive small chrome spice jar and blank pcb board... and by the evening I had made a ribbon mic :razz:!

Have a look at the pics that detail step-by-step construction here: http://elfito.myphotoalbum.com/view_album.php?set_albumName=album02

The secret of this light-speed construction method (and quite tidy too, as I learned quite a bit following my first project, chronichled here: http://www.groupdiy.com/index.php?topic=7218&start=0&postdays=0&postorder=asc&highlight=

Anyway, this time, just to experiment and to work around the spice jar, I decided to make a cardioid ribbon. One concern is the sound bouncing about inside the chrome jar and building up unwanted, boxy reverb. I am quite confident I can work around that by fitting a taffeta (or wool, or foam) pad a couple of cm behind the iron, though I'll fully know what to do when the trafo is here and I do the tests. On th eother hand, if you place your hand behind a standard, figure of 8 ribbon mic, the sound becomes more focused, so this is the part of it that I want to explore.

By now, have a look at the pics and let me know if you have any comments/ideas :green: .

 

[bcarso]

"I started the day playing my bandoneon a bit (one of those weird, very noisy acoustic instruments) until my girlfriend's friend arrived and the requisite peace necessary to rehearse had vanished."

Heh. I love the idea of vanishing peace TO rehearse with a bandoneon...

Actually that instrument gets a lot more respect now since the wider recognition of the late great Astor Piazzolla---a far cry from the days when one of the popular bumper stickers among Local 47 musicians in LA read "Use an accordion, go to jail."

I should do a one-day preamp to go with your mic. Congrats on the project.

 

[El Fito]

Thanks, mate! You must be one of the very few people who knows what a bandoneon is, or what it sounds like! I am sure you'll agree that a ribbon mic is the best match for the sound of a bandoneon... :grin:

 

[Guest]

[quote author="El Fito"]comments/ideas :green: .[/quote]
Yes, pressure ribbon...
1. use horn (two cylindres) on the front side of the ribbon
(like in Bayerdynamic handheld)
2. that magnetic flux returning wires ??? can not be enough.
use more that wires.
3. you must make labirinth to the back side of the ribbon.
I don t know, what type of labyrinth fits for your case. And how to

xvlk

 

[Scodiddly]

Wow - that's great! Wonder what it'll sound like... :sam: :sam: :sam:

 

[maneco]

Congratulations for your work...and i know how a bandonion sounds...i did an electronica/tango blend project,and a bandonionist fellow recorded some tracks...great sound!

 

[ToobieSnack]

hey fito...

COOL! i remmy you talked about this shaker can and now I see.

and ....hmmmm....1 day....ok we both know that after design changes it will be more...haha...not to poke a hole in your ballon...but realistically.... :wink: .... that's pretty fast...and better than listening to annoying, giggly, chatter.......no offense girls... lol :grin:

Great acomplishment though.....that material you had told me about (the PCB) that works real well and easy to sculpt.

I do know one thing.....NICE magnetic return circuit added to this mic.... :grin: ....see ... that was easy ...right? :grin:
are you only using 2 magnets this time? (per side)

still using the U channel or is that different..(can't tell from the pics)

ALSO: i highly recommend tha you take note to what xvlk is saying ....he really knows what he is talking about...

he thinks your humbucking loops are too thin.... which may be debate-able...but xvlk may also win that debate.....

More importantly:
this horn behind your ribbon....I think of it like a folded bass cabinet.
this is how I would do it...
i would make 2 walls about a 3/8" from the edges of your ribbon...leaving approx 1" from the bottom of the container...
at the bottom of this corridor i would put a wedge ....90% L metal which will give you 2.... 45% angels off to each side.....cover the corridor walls with felt or velvet and leave the angles metal exposed...

Also in the outside chamber I would put 45% angle in the corners...maybe with some epoxy or something....leave these angles un-covered so they will reflect any sound waves up into your outside chamber and THEN let the damping do it's work there....so your damping material in the outside chamber would NOT go all the way to the bottom..

in the outside of your corridor fill this with some porous material like fibreglas or a material like you would put in your air conditioner as a filter
in other words not too dense....and hold... I'll tell you why

now ...somewhere at the top sides of your design you will need a slot for the air to enter/exit the outside chamber ...to balance the air pressure
i'm not REAL sure this is necessary but it would make "common" sense.
you know ... we always try to balance the air pressure from one side of the ribbon to the other.



does this sound good/helpful?
have I explained my idea's well?

what do you think of my theories?

I have no reference for these theories...just a brain cell jumping up and down in my head ...haha...lol... :grin: THAT DAMN BRAIN CEL ... LOL

let me know what you think...all.

hope this helps

as always good luck
later
ts

 

[Guest]

[quote author="ToobieSnack"] xvlk is saying ....he really knows what he is talking about...

he thinks your humbucking loops are too thin.... which may be debate-able...but xvlk may also win that debate.....
[/quote]
Tobbie, I not say nothing about hum-bucking. I say about
magnetic-return path. Or about it, what looks about it.
But - after deeper view - return magnetic path from SnPb Alloy ????
What about Sn relative permeability 1 ????? Without effect.
Or is it iron only with SnPb on it???

Hum - bucking of this mic is somewhat curius. There are twoo big loops.
I think, that loops may be with the minimal area generally with hum - buck
or without it. It is not too thin. Ribbon itself have under two micrometers
thick and that copper have order of thicker.

And Tobbie, I not want to win debate. I am only interested in topic.

 

[El Fito]

Xvlk and Toobie, thanks for your useful suggestions, and thanks everyone for your remarks.

Toobie, I am not completely sure I follow your rogue brain cell 100%, so it'd be useful if you could show me a graphic of what you mean. I picture a couple of aluminium angles, placed horizontally facing each other inside the mic forming a labirinth, and felt in their inside. Is that about right? Now, xvlk and Toobie, I imagine the idea of this labyrinth is to make a sort of bass trap?

Another thing: I don't know what material this shaker is made of. Neither steel nor aluminium, and it is so hard it takes forever to drill a hole through it despite being quite thin. Do I really need an air outlet? I'd rather not, but I guess I'll never know until I experiment using my own ears.

The magnets are four neodymiums (two a side) and their thickness is 5 x 5 mm, which is roughly the same as the gap. Now, according to PRR's magnet specialist mate, with such an arrangement, given the strength of neodymiums, you shouldn't need a magnetic return path at all. I did it just in case using a 3 mm mild steel rod.

I see the point about the Beyer handheld ribbon mic, but I don't know that I'd like to mimic that mic, as I've heard fairly poor reviews about it. I am building knowledge on the basis of my last mic, which started off with two magnets a side and now has four a side but, having said that, the additional magnets give it a small boost (not drastic) which this one will perhaps get with the return path and the fact that it is cardioid. At the endo of the day, I guess we'll know when we hear it... :grin:

 

[ToobieSnack]

And Tobbie, I not want to win debate. I am only interested in topic.

xvlk...sorry if i was not clear with my statement .... this was a kind and part joke or a friendly remark...

because your info is so accurate and well researched that you are most often correct and exceedingly knowledgeable....this was a compliment... :grin:

i will try to be more clear from this point on....

thanks for straightening out my misconception....we have some language barrier to evercome at times.... this is ok though... i am happy to hear ALL your fine comments and suggestion ... thanks... :grin:

fito.... yes this is similar to a bass trap... have you ever seen a folded bass cabinet ... the speaker faces backwards and is folded by 45% ...then another 45% angle to the opening at the front ... so the sound travels in a U shape ...(turns it backwards...or opposite from the direction of the speaker.

you are correct about this corridor .. and in addition to this...hmmmm

well... as an analogy .... look a the sound as if it were rain and at the bottom of the mic is this "roof" structure....sloping 45% in one direction toward your poles... and one facing the other direction..... (adding the 2 45% will give you 90%)

OK but since rain is not sound waves the waves will bounce off this "roof" at exactly 90% also which will push the waves directly into your side walls...this is where an additional 45% angle is needed to direct the waves upward into your outer chamber.... it is like when you are playing billiards... with no english the ball travels in perfect rectangles ... at 90%

As it pertains to your magnetic return circuit:

as xvlk and marik have said .... a neo barely NEEDS a magntic return circuit...(air works OK)... as you have experienced with your previous mic...

this small addition to your structure ...of the steel wire ...should be benificial...and may make up for the fact that you are only using 4 magnets total....

i think what xvlk is saying is that the physical elemental make up of the types of metal used here my have some effect on your design....

i am not familiar with xvlk's abbreviations (or elemental reference to the metal types) ... as always if xvlk says it is worth considering ...he is probably right! :grin: ....again....haha...lol ... :wink: :grin:

xvlk... yes the topic/facts are most important here ..... and ... we can all win .... and when in the pursuit of the facts we have some small differences in our ideas ... it makes perfect sense to discuss these differences ...and ... this is not really thought of as being a debate with one winner .... we all win at the discovery of the absolute facts..... :grin:

thanks you very much for your excellent ideas and information.
i have great respect for you .... always...
thanks
ts

 

[Scodiddly]

Probably the shaker is stainless steel - looks that way, and would be harder to machine.

Toobie: A folded bass horn isn't folded to do anything special to the sound, it's just folded to make a smaller package instead of a long, cumbersome horn.

 

[PRR]

> make a cardioid ribbon.

As built, it is omni up to a few KHz, semi-cardioid above that due to the large frontal size, but also comb-filtered due to the size of the back-chamber.

Half-fill the back with diced wool (not dacron!) felt to kill the comb-filtering. 45 degree baffles don't work any better here than they do in race-car mufflers (a little teeny bit).

Your magnetic path seems reasonable to me. I think the PCB return traces are reasonably low-resistance compared to the ribbon, and it does have hum-bucking.

 

[El Fito]

PRR, thanks for your comments. It's like someone has just turned on the lights!

Then I gather I must be more or less on the right path, so far as I fill the mic body with some suitably woolly stuff!

As for the mic body, nope, it's not stainless steel, as it does not stick to the magnets and it is immune to soldering. Go figure, some alien metal maybe? :grin: Not looking forward to doing any more work on these hardy canisters any time soon!

 

[PRR]

> it's not stainless steel, as it does not stick to the magnets and it is immune to soldering

Good stainless steel won't stick to a magnet and can't be soldered at home. Take a spoon from the kitchen, try drilling soldering and magnet-sticking. Or talk to someone who knows low-price stainless steel sinks: if a magnet sticks to a SS sink, it will be prone to showing rust-stain; if not, then it has enough chrome to break-up the iron so it won't rust and won't stick.

If it was Aluminum, you would not complain about drilling it. If it was chrome plated copper/brass, it would drill easy and also you would recognize penny-color drill-chips. Titanium is too exotic for a flour-shaker; aliens don't use flour-shakers (they levitate flour out of the sealed bin right onto the dough). But good-quality stainless steel IS a common metal for small kitchen objects.

 

[ToobieSnack]

Toobie: A folded bass horn isn't folded to do anything special to the sound, it's just folded to make a smaller package instead of a long, cumbersome horn.

yes i agree completely .... :grin: and i will add

that as the sound attepts to leave through the chamber and is isolated and absorbed there..... this would be a good thing.... and the corridor will also allow the sound waves to be very quickly evacuated and THEN damped.....

ALSO: I completely agree that energy in motion tends to stay in motion until it's converted to heat.... so...bouncing waves will continue to bounce ... but directed to an "mini" anechoic chamber ..... :grin: and is absorbed and converted to heat .... :grin:

of course as PRR stated ...equally effective.. and cheaper.. easier to implement ...and considering availability of material ....and also considering work effort... :grin:
direct damping seems to be your answer.. :grin:

I might be over thinking the whole deal....
it's in your hands fito ..:shock: :grin: :shock: haha lol

later
ts

 

[kvintus]

aliens don't use flour-shakers (they levitate flour out of the sealed bin right onto the dough)

:green: :green: