yikes alot of gain needed

[SCOOBY]

two dozen wow i think u might need a lil rehab
lol
i'll be having some fun in here i see.

marik the v76as far as i see will be a from scrath kinda deal which i'm not to keen on seeing as the last thing i made was a mic cable lol.
i'm kinda looking at pre's that i can get a premade pcb for and gather materials easy so the sca's seem like a best bet deal. i've been tinkering wit little stuff on pcb's since i was 11 (11 years) but nothing serious and i have only basic level understanding of circuit design and reading pcb's and schematics for them. so it seems the g76 is a lil aheads of me. unless i missed somethin in my quick info search.

 

[rodabod]

[quote author="Marik"]
No. Against our intuition, the thinner ribbon does not affect HF... at least directly. The thinner ribbon has less resonant modes and better sensitivity. The later happens until the certain point though, when the ribbon mass becomes equal to this of loaded air.
[/quote]

I've got a very nice BBC engineers book which has an excellent chapter devoted to ribbons - it discusses the optimum (compromise) ribbon thickness for maximum output - there is a threshold where thinner ribbons will obviously output less.

I'll see if I can get some scans sometime.

 

[Marik]

[quote author="rodabod"][quote author="Marik"]
No. Against our intuition, the thinner ribbon does not affect HF... at least directly. The thinner ribbon has less resonant modes and better sensitivity. The later happens until the certain point though, when the ribbon mass becomes equal to this of loaded air.
[/quote]

I've got a very nice BBC engineers book which has an excellent chapter devoted to ribbons - it discusses the optimum (compromise) ribbon thickness for maximum output - there is a threshold where thinner ribbons will obviously output less.
[/quote]

Yes, I have the book. The super thin foils, besides, will have too much DCR, resulting in higher noise and bass loss.

 

[ToobieSnack]

SCOOB glad all is fine .
r bod YA! Plz post that info .. ya know i would love it .. :grin:
as my others :wink:

marik ..
thanks again :thumb:
and so.. if ..

2- the distance from the front on the rbbon (around the frame . pole peices,magnets and body structure) to the back of the ribbon ..
(the shorter the distance the better)

is this correct?



Yes.

then my high frequncy respose is locked into my body/frame design? ..so ..
is it possible to estimate my high frquency response based on my distance of 1/2" (or say 6mm) from the front to the back of my mic body
hmmm also does this include the distance the sound must travel inside the mic eg. around the mic body then back into it to the actual surface of the ribbon?
if so tht would be an additional 6mm .. i am a little confused..
ts

 

[rodabod]

[quote author="Marik"]
Yes, I have the book. The super thin foils, besides, will have too much DCR, resulting in higher noise and bass loss.[/quote]

Marik, can you explain the higher noise?

I assume this must be current related - ie. current noise is greater when pulled through a higher resistance since it makes a greater voltage.

But, I don't understand why this would happen.

As long as the output impedance of the mic is low, where is this noise coming from?

Is it current noise from the mic input? This would be stepped up by the trafo which would appear across the ribbon as voltage noise. Have I gone mad? :razz:

 

[rodabod]

[quote author="ToobieSnack"]
then my high frequncy respose is locked into my body/frame design? ..so ..
is it possible to estimate my high frquency response based on my distance of 1/2" (or say 6mm) from the front to the back of my mic body

hmmm also does this include the distance the sound must travel inside the mic eg. around the mic body then back into it to the actual surface of the ribbon?
[/quote]

TS, you can roughly (ie theoretically) calculate the frequency response using simple maths.

It is just the distance between the front of the ribbon and the path to the rear of the ribbon on the assembly.

If you look at your assembly, imagine talking in to it an d then imagine how the sound waves will hit the front and also travel round the sideand hit the back. This is the path difference.

Do you realise why most ribbons are theoretically flat up to roughly 10KHz and then fall at 6dB per octave thereafter? It is quite interesting.

 

[ToobieSnack]

thanks rbod so ..
now that i am really thinking
my ribbon is suspended half way soo..
i have 3mm from the front outwards... 2.5mm around the front side... 6mm to the back ...2.5mm around the back side ...and an additional 3mm to the back of the ribbon... so a total travel of 17mm

rbod can you illustrate the formula using my measurements?

that would be super AWESOME! :thumb: :grin:
later
ts

 

[Marik]

[quote author="rodabod"][quote author="Marik"]
Yes, I have the book. The super thin foils, besides, will have too much DCR, resulting in higher noise and bass loss.[/quote]

Marik, can you explain the higher noise?
[/quote]

EIN (Equivalent Input Noise) formula includes resistance.

[quote author="ToobieSnack"]thanks rbod so ..
now that i am really thinking
my ribbon is suspended half way soo..
i have 3mm from the front outwards... 2.5mm around the front side... 6mm to the back ...2.5mm around the back side ...and an additional 3mm to the back of the ribbon... so a total travel of 17mm

[/quote]

Not bad. Your theoretical null is at 20K and the response starts falling at about 10K.
To find it out you should translate wavelength of front to back path (in your case 17mm) into frequency. You can find an online calculator to do it.
Its value will be your "theoretical null". "Theoretical" is because in practice there will be reflections, which will somewhat kick it off. "Null" is because the signal will be 360* out of phase and will be cancelled.

The response starts falling an octave below this value.

 

[rodabod]

Right TS,

That sounds like some nice measurements you have there; nice and small.

Haven't read the formulae for a while, but here goes:

Y (Lamda) = wavelength

d = path difference

c = speed of sound

"Above d/Y = 1/4 , the velocity increases rapidly with increase in frequency, and theoretically the output of the microphone falls and is zero at d/Y = 1.

I may get this wrong, but bare with me! I will correct it!

d = c / (4f)

We want to find f.

4fd = c

f = c / (4d)

f = 331 / (4 * 0.017)

f = 331 / 0.068

f = 4868 Hz = ~ 5KHz

Oh bugger, that doesn't sound right.

Well, let me put the calculation into perspective before correcting it:

The book says that d = 0.33 inches (8mm) gives a theoretical loss of 1dB at 10 KHz.

I'll need to read the text again!

 

[rodabod]

No, it's actually ok.

For their example, we have a d/Y = 1 at 40 KHz.

Therefore as Marik suggests, your cancellation will exist at 20 KHz.

 

[rodabod]

[quote author="Marik"]
Not bad. Your theoretical null is at 20K and the response starts falling at about 10K.

The response starts falling an octave below this value.[/quote]

Marik, where did you get the info for that?

The BBC book says that the response falls (I assume by 6dB per octave) when d/Y = 1/4. This would suggest 5 KHz, and therefore the output would be ~6 dB down at 10 KHz.

I would have thought the output would be half, at half of the null frequency which would be -6 dB.

 

[ToobieSnack]

thanks marik and rbod :thumb:

hmmm this all make me pretty happy .. :grin: :sam:
so my high end response is theoretically identical to royers?
here is the royer frequecy plot:

me likey:grin:

is there a way to calculate theoretic low end response?

later
ts

 

[rodabod]

[quote author="ToobieSnack"]
so my high end response is theoretically identical to royers?
[/quote]

Well, not necessarily.

For a start, I would maybe take that Royer frequency plot with a pinch of salt. I'm not saying it is wrong, but many frequency plots of mics can be a bit optimistic. For a start, I doubt it would that flat in reality.

The assembly dimensions limit HF extension. I have seen pictures of the Royer motor and I can confirm that yours sounds quite small in comparison. So, maybe yours will have a similar HF extension.

Having said that, it doesn't mean that they will sound the same.

I was wondering about the Royer. Do you think it has an in-built bass roll-off in the electronics to even out the response? I think I heard somewhere that it didn't have the usual ribbon bass response.

I wouldn't worry too much about HF extension. It doesn't mean that it will necessarily sound good - there are other factors too.

Now, when are we going to see the photos? Come on! :razz:

 

[Marik]

[quote author="rodabod"][quote author="Marik"]
Not bad. Your theoretical null is at 20K and the response starts falling at about 10K.

The response starts falling an octave below this value.[/quote]

Marik, where did you get the info for that?
[/quote]

I usually consider corner frequency at -3db (whether it is right or wrong). From personal experience, measuring many ribbons with different path lengths and comparing them to calculated value, I found that usually -3db falls at 1/2 wavelength. Theoretically it should be -6db, however it is not that I've experinced in practice. It is worth noticing that below 1/4 wavelength the response is ruler flat.

 

[ToobieSnack]

Now, when are we going to see the photos? Come on!

ya and then some huge company will skipper on over to the lab and claim i am violeting their ornamental design patent that doesn't even have any drawings posted on their patent page at the ustpo site. 'lololololololol :wink: :grin:

i found a really chap patent attourney .. it won't be too long .. :grin:

also BTW apparently it is better to have a 'patent pending" status rather than an actual pataent at this point ..
with a "patent pending" you still retain all rights but yo can discuss ideas and alter the design and it is good for a year.. :idea:

maybe yours will have a similar HF extension.

ya that is all i was really saying ..

Having said that, it doesn't mean that they will sound the same.

well actually i'm not shooting for the SAME i am shooting for BETTER :wink: :wink: :grin:

or a start, I would maybe take that Royer frequency plot with a pinch of salt. I'm not saying it is wrong, but many frequency plots of mics can be a bit optimistic. For a start, I doubt it would that flat in reality.

this is right from the royer patent .. so are you saying royer just made this up? :shock:

hey you got any pics of that royer motor for the forum :wink: :grin:

as for the bass roll off i haven't heard anything about this ..
i have been looking at the royer that does not have the active electronics . now i'll have to search the uspto for that too .. arrgghh lol ahh i'm gonna love it lol.
later
ts

 

[ToobieSnack]

OH and BTW SCOOB you should actually be pretty proud of this thread yo created . this is THE best ribbon mic discussion i have been involved with at the Lab .. hope you are having fun too :wink:

the formula stuff rbod posted was super cool! :thumb:

and since marik has stated ruler flat response below 1/4 wavelength all we need is a formula for the low end null point/roll off... marik? ... rbod?
... xvlk ? (hopefully) :grin:

i just wish xvlk were here ..
hey marik you have his e-mail? :grin:

HHhheeeeyyy xvlk .. hehe :grin:

later
'ts

 

[Marik]

[quote author="ToobieSnack"]
is there a way to calculate theoretic low end response?
[/quote]

No. Too many factors influence it to make calculations any practical.

this is right from the royer patent .. so are you saying royer just made this up?

Looking at many ribbon mic frequency plots makes me think where the hell it is coming from.

well actually i'm not shooting for the SAME i am shooting for BETTER

Well, it is probably not that hard. But you have to specify in which respect better?

ya and then some huge company will skipper on over to the lab and claim i am violeting their ornamental design patent that doesn't even have any drawings posted on their patent page at the ustpo site.

Com'on, you have made an ornamental ribbon motor :shock:

Just make sure not to patent some of our ideas :wink:

 

[rodabod]

Here are the motors from Royer:

I didn't ever mean that the Royer response chart was "wrong", I just thought it looked a little smooth - Beyer ones are similar, but they say that the response follows the graph roughly and varies up to X dB.

Good luck with the TS ribbon. I hope you don't have to argue over patents until you are blue in the face.

 

[rodabod]

Here are the motors from Royer:

I didn't ever mean that the Royer response chart was "wrong", I just thought it looked a little smooth - Beyer ones are similar, but they say that the response follows the graph roughly and varies up to X dB.

Good luck with the TS ribbon. I hope you don't have to argue over patents until you are blue in the face.

 

[ToobieSnack]

ya and then some huge company will skipper on over to the lab and claim i am violeting their ornamental design patent that doesn't even have any drawings posted on their patent page at the ustpo site.


Com'on, you have made an ornamental ribbon motor

this is kind of a joke carried over from the violet/BLUE threads marik .. :grin: skipper/violet-ing get it? lol

but ornamental design "of the body/grill (exterior) is not to be overlooked as important ... not an "ornamental design of a ribbon motor" lol :grin:

Just make sure not to patent some of our ideas

a ribbon between 2 magnets is nothing new .. i have checked that with the patent office ...

i have basically taken the things i have learned through experimenting,
theories discussed here on the forum (not individual projects)
discussions with other friends and collegues
inormation on ribbon mics AND ribbon tweeter units i found at the patent office through research
( all this research is why i hven't been around much lately)
and info found on websites... then....
i looked at the available material i had at hand ....
and waited for an epiphany .. :idea: ...
and in the middle of the night while contemplating and looking at the ceiling ... BAM! :shock: :idea: :shock:
it happened ..
i promptly set out to build it ..
built 2 prototpes i wasn't happy with .. (the d-1a and the d-1b) and
2 more af a third prototype .. and kabing! happy happy ...
so i guess you could say i was guided mostly by my failures .. :wink:
cant wait for the d-1d tht will will require some cutom grinded neo;s though .. :shock: expensive OUCH!

rbod slammin pics brother!!!

still can't make out some of the details but cool none the less .. :thumb:

Looking at many ribbon mic frequency plots makes me think where the hell it is coming from.

ya i hear you marik .. looking at the patent info it seems like they are trying to mislead us a litte bit

on the patent it says torriod trafo .. the trafo in these pics are clearly E I lams ..
also the patent says 1:25 ratio and i see 1.45 printed on that trafo ...
this might be a misprint .. i assumed they were using a 1;40 trafo before i looked at the patent .. now of course this may be a diffferent model ..

does anyone know where to get a torriod ribbon mic trafo ... ??

where that darn trafo expert ??? :grin: :wink: hehe ...
later
ts