TS-1 ..ribbon mic*IT WORKS!! **HORAY**pics / completion info

[El Fito]

But don't you think that the input impedance (0 to 0.25 ohms) of sowter's 40:1 is a bit on the low side for a homemade ribbon mic, possibly using a fajita wrap as a ribbon element?

 

[Marik]

[quote author="El Fito"]But don't you think that the input impedance (0 to 0.25 ohms) of sowter's 40:1 is a bit on the low side for a homemade ribbon mic, possibly using a fajita wrap as a ribbon element?[/quote]

No. Fajita/cigarette wrap is a thicker material, so will have low resistance and more or less should match the transformer input.

 

[ToobieSnack]

First:
thanks for your comments

and thanks for jumping in there Marik
I believe waht our forum friend is trying to say is:
to match my trafo with my ribbon

thanks for that reminder
I will have to wait and see what kind of meassurements i get when all the mechanical connections andthe magentic return circuit are considered.
BTW:should i be concerned with resistance of the ribbon only or would i include all these other items in the circuit (the clamps and the magnetic returncircuit)?

I am using this cigarette foil only because it is cheap.
I will eventully replace it with more compliant material.
So you see I will possibly have 2 trafo requirements, one for each ribbon.

Second:
progress update:
Last night i finished up the ribbon clamps.
I had to make some compromises in my design , but the potential to comply to my original design still exhists. I'm just skipping over one obstacle for now becuase of a raw material availability issue. The compromise involves fine tuning of the ribbon so careful ribbon placement should be sufficiet for initial tests.

third:

I sourced some Neodymium magnets:

DAMN DAMN DAMN DAMN DAMN

these things are strong!

11,400 guass 78 lbs holding force!!!!! for the type 30's

and 12,150 gauss for the type 35's!!!!

one rod or "plug" as it is termed, had a holding strength of 115 lbs!!!!!!!!!!!!

I'm trying to imagine 2 bar magnets 1"x2"x1/2" each with 78lbs holding stregth...facing each other ... with a 1/4" gap between them....whoah!!!
:shock: :shock:

how would I get them apart if they got stuck together...lol...lol...ok but seriously..

is epoxy on a plastic even strong enough to keep them seperated??

Also: the supplier stated that the standard size of these magnets are:
1" x 2" x 1/2"
and that I would run into a brick wall trying to find anything else;
the cost for grinding and plating the mag to my 3/8" spec would be $60
per lot. the magnets are quoted at $15.00 each
the setup/ginding would be per lot so... 1 or 20 will still cost the $60 fee.

Marik are you using this size?

Any info for magnets availability or grinding will be sincerely appreciated.

PS i think a local machine shop will be a better candidate for the grinding and plating I will check

fourth:

I have some questions

what effects will ribbon tension have on the output or frequency? frequency right?

would I calculate approx output using flux/ribbon resistance/trafo ratio?

Magnetic Return Circuit

OK I have found in the metas:
a magnetic return circuit basically involves
returning the top ribbon connection down both sides of your magnet structure through some kind of soft metal like iron or brass.

In my RCA 74b the magnet structure is completey isolated using 4 rubber mounting grometts.
The brass return material has a small air space between itself and the magnet structure.
the return circuit is straped at the top with a small piece of threaded tubing
and at the bottom as the u of the continious brass strap (2 inches of distance form the magnet struct at the bottom

QUESTION: what is the significance of the "air gap"?
could a gap of epoxy do the same trick"
what size gap am i shooting for?

OK I forget what number I'm up to now ...lol BUT...

POLE PIECES:
I'm trying to understand the theory of saturation and pole peice orientation/size.
Currently my magnets are my pole peices
Will the additional material I use determine the saturation?Best material/options?
Currently my magnets are completely seperated with no strapping between the 2 magnets.
Should I strap the 2 together.
1/8" on back and front near the tops and bottoms ok?thickness of straps?

Also:
EG lets say:

I gingerly cut a tiny groove in my magnets and epoxied a razor blade cut to a sliver, and epoxied it into my groove sharp side out.
then connected each end of the razors to pieces of iron directly positioned on the other side of the magnet, joining under and over the magnets.

sound good???

this sound pretty hard ... I'm wondering about the pros/cons

ALSO:

should I be tring to "wrap" my magnet with this material? for maximum saturation?

well my fingers are sore and my mind is boggled
so I'' sign off for now.

thanks for all your info/comments
I'll keep you updated

thanks for everything everyone.
ts

 

[El Fito]

Toobie, it seems that we are progressing at a similar pace in our projects. As for the magnets, I ordered four scalextric neo magnets from evilBay. They arrived today. The size is 1" x 1/4" x1/16". You can see what they look like here: http://cgi.ebay.co.uk/ws/eBayISAPI.dll?ViewItem&item=5953087084&rd. It seems that each one of these pulls about two kilos and I gathered they would be enough, provided I glue two of them vertically one on top of the other on either side of the ribbon gap. They are pretty close to unmanageable because their pull is super strong. I've had several tries at epoxying them in place and had to check, double check and triple check polarities before gluing them on the sides and then opposite each pair. In hindsight, it would have been a lot easier to glue them first to a ferrous surface and then build the rest of the mic frame around that, but I guess I am past that stage because my mic frame is complete. I came up with a ribbon adjusting mechanism that allows for ribbon tightening or slacking once the ribbon is fitted. I have plans to build a completely adjustable mic next, to include this feature, as well as a mechanism to vary the gap between the ribbon and the magnets, thus varying the tone (I guess?), or allowing to vary the magnetic field between magnets that may be too strong. I'll post photos as soon as I know how :shock:

 

[ToobieSnack]

Fito thanks for your comments.
sonds like you have some good ideas
my magnets are charged side to side ( if they were dominoes it would be front and back)

opposing the two opposite poles (front / back) and mounted side to side.

provided I glue two of them vertically one on top of the other on either side of the ribbon gap.

I'm not sure of your arrangement...looking forward to pics....

currently (about 30 mins) i considered using some smaller Neo's on the sides of my ceramics as sort of a "super charger" for my magnets.
(rather than alter the entire design)
I wonder if this is possible?
Can anyone comment?
this alteration will save me a LOT of time and would be very easy to implement.

As alway much thanks
and fito good luck
ts

 

[ToobieSnack]

hello people
I have found this great reference on FAQ magnets
Info for cutting and shaping Neodymiums etc
they sell magnet wire too.
havn't checked their prices yet
check it out

http://www.wondermagnet.com/magfaq.html#q74

later
ts

 

[El Fito]

Toobie, I have finally managed to upload a couple of photos of the innards of my ribbon mic. Take a look at this http://elfito.myphotoalbum.com/view_album.php?set_albumName=album01 and tell me what you think. How does it sound? I haven't got a clue yet. I ordered Sowter's 40:1 trafo yesterday. Not cheap at all! Plus delivery won't happen anytime before 2-3 weeks Anyway, I will now turn my attention to the housing, which I have started to make with a tin of spam -classy! (first time I try it, and hopefully the last ... or until I build a new mic). Will try to give it a classic RCA 44 kind of feel. I'll upload some pics when there's some progress worth showing.

 

[Marik]

[quote author="El Fito"]Toobie, I have finally managed to upload a couple of photos of the innards of my ribbon mic. Take a look at this http://elfito.myphotoalbum.com/view_album.php?set_albumName=album01 and tell me what you think. How does it sound? I haven't got a clue yet. I ordered Sowter's 40:1 trafo yesterday. Not cheap at all! Plus delivery won't happen anytime before 2-3 weeks Anyway, I will now turn my attention to the housing, which I have started to make with a tin of spam -classy! (first time I try it, and hopefully the last ... or until I build a new mic). Will try to give it a classic RCA 44 kind of feel. I'll upload some pics when there's some progress worth showing.[/quote]

El Fito,

It is a very nice looking ribbon, and I am sure it should sound very good.
I like your vari-tension assembly and humbucking arrangement.
What did you glue the magnets to? It seems like some plastic. For the magnets you use, it is a good idea to use cut to size iron strips, instead. This way you will gain more efficiency, and you will get little more output, pushing the flux in the gap to its almost target value. You don't have to close the magnetic return circuit, though. Keep us posted as to the progress.

 

[Marik]

Toobie,

You have a lot of ideas, and I know this feeling of "brain rush" very well. It seems that you start doing things randomly, which is never a good idea. I'd like to urge you once again, very carefully go through the ribbon part of the Meta and try to absorb all the information, reading and re-reading again and again.
As I wrote earlier, all the parameters, materials, dimentions, magnet strength, etc., in ribbon microphones are very tightly connected, and were covered here in a quite systematic way. If you don't understand something, please ask. To be honest, I have hard time understanding as for what you want to try to accomplish. It will take you some time to get a clear concept, but once you get it, it will be much easier for you to move on with your project, and ultimately, it will save you a lot of time and money.

 

[El Fito]

Marik, thanks for the compliments! It's good to know that I seem to be heading in the right direction. The magnets are epoxied to a brass frame. Lots of soldering here! I'll let you guys know as soon as I have some more news/pics. Cheers.

 

[Svart]

something has always been in the back of my mind.. what if you took a large ring magnet (like what's in a speaker) and cut a slot through it and used that gap for the ribbon?

 

[mikka]

Just need to tell you bunch of DIY's that my jaw is on the floor and I'm grinning from ear to ear just reading your posts. Unbelievable........... :green:

 

[ToobieSnack]

Mikka
thanks for your kind comments

If your jaw is dropping now get ready... cause i'm going to post some updated pics today..

what if you took a large ring magnet (like what's in a speaker) and cut a slot through it and used that gap for the ribbon?

RCA 77 uses this design (more like 2 horse shoe magnets)
if I am undertanding you correctly..this would work if the poles are agganged correctly. i think you would have to determine the polarity of this mag before cutting. (be careful of dust/heat ..... use a water cutting wheel like used for ceramic tile)

Marik .... I'm readin man I'm readin!!!!! till my eyes won't work any more lol (but seriously)

I'll post the pics and maybe I'll be better understood as to my goals.
Now I'm just trying to increase the efficiency of my magnets and add some energy focus to the ribbons.

I'll be 90% done tonight.

Look for the pics

thanks everyone
bye bye for now (bbfn)
ts

 

[ToobieSnack]

OH ****!
Fito:

I just realized I forgot to comment on your design....

Looks VEERRRYY nice.

I like your adjuster too.

i like the sliding block idea.

My design allows for left/right adjustment too

I had planned in forward/backward...twist left/twist right too ...but

i skipped over it for now.

good luck...

BTW I'm waiting on a trafo too. (thanks ykwya)

anyway... looks good keep up the good work!
ts

 

[El Fito]

Thanks mate. Doing the body whilst waiting for Sowter to deliver. I'm working with an amazing material, which I think is known as "German Silver" (also known as alpaca). It looks really high class if you take the time to work it properly. Basically, it looks just like silver. I had a bit of it lying around and decided to use it for the yoke and other bits and pieces. I'll try to get some more when I get the chance. I think I'll go to the DIY shop this weekend and look for some nice perforated sheetmetal for the grille. I also made a couple of thumbscrews that go on either side of the yoke. Pics coming soon.

 

[ToobieSnack]

here's a pic update on my progress

sorry it took so long Marik/fum (and others)

enjoy

body and element

back of element

front

Note my tension/alignment adjustment thingy
black knob = tension .... gold knob=L/R adjust

RED (not shown) bottom ribbon contact....BLUE and WHITE wore for mag ret circuit

hey RED / WHITE and BLUE ....ok I just had to do it...... usa... usa ...lol

still looking to add iron to this. for increasing magnetic power to the ribbon or whtever ...????
suggestions?

anyway must go for now
as always comments suggestions welcome.....
enjoy
ts

 

[ToobieSnack]

deleted (unrelated babble)

 

[El Fito]

TS, that mic's looking good. And sturdy like a tank! just look at those magnets! As for my project, take a look here http://www.groupdiy.com/index.php?topic=85265#85265 where I've posted some progress. After a busy weekend, the body's now ready and I'm still waiting for that Sowter trafo. This thing had better work...

 

[ToobieSnack]

hey all
today is a day for celebration MAY 3 2005

MY mic has been connected and....::suspense:::: ....::drum roll:::: ::Fanfare::...ta-dah

IT WORKS!!!!!!

seems to sound pretty good too. ( I' using a real noisy tube mic pre right now)

output comparable to my RCA ( I'll double check that ... it was really dark and the knobs aren't well lit.)

I'll get my MOTU system up and try to get some decent audio clips..(figuring out which mic pre' to use really)

anyway
HAPPY HAPPY ..JOY JOY...

EVERYONE HAVE A BEER!!!!

:guinness: :sam: :guinness: :sam: :guinness: :sam: :sam: :guinness: :sam: :guinness: :guinness: :guinness: :sam: :sam: :sam: :guinness: :guinness: :guinness: :guinness: :guinness: :guinness: :guinness: :guinness: :guinness: :guinness: :guinness: :sam: :sam: :sam: :sam: :guinness: :guinness: :guinness: :guinness: :guinness: :guinness: :sam: :guinness: :guinness: :guinness:

 

[Consul]

Congratulations! :guinness: :thumb:

Someday, I'll know the thrill of building something that works...