Preamp to activate a ribbon Mic

[Violinist]

Hi all

It's almost one year I would like to buy a Ribbon Mic, i'm oriented to the APEX 205 of course applying all the mods I got here in this forum, but I slowed down my "GAS" especially for the output signal and the fact that it seems very sensible to Phantom Power.

The output signal will constrain me to spend a lot of $$$ to buy a valid preamp with 65-75 dBs gain
The Phantom Power sill be my pain, because often I forget it ON (when I use my other mics which are condensers).

I was thinking: why do not study a circuit to integrate into the mic, which uncouple the ribbon mic from the phantom, and gives some dB of gain in order to avoid to spend many $$$ for a preamp?
I mean: not certainly something super pro, but that just can safely manage a ribbon mic

I thought a little diagram that I would like to put under your attention, in order to see if this can work or not, or if it can work with some modification.
In attachment there is the schematic.

For the input stage I used 2SK170 FET due their low noise.
The part of the diagram made by the 2 BJTs and the 2 FETs, I already successively used it for a mic I built and I will publish pictures etc in another already opened topic.
This is a Shoeps' architecture and, as far as i understand, has a gain of 1:1 offering electronic balance.
Here, in this schematic, I took that diagram with some little modification in terms of voltage values (30V instead of 12V) just to give a first idea.

The first part of the schematic, is the input stage I added thinking perhaps can help.
It's the classical "micro-amp" architecture which has "high gain" (depending from the trans-conductance of the FETs).
The input impedance is on paper 1M.

I also successfully used this architecture separately from this schematic, for other purposes

My idea was: this stage, can uncouple the ribbon motor+transformer from the Phantom. Indeed not any part of it is reached in any way by the power supply.
At the same time offers some dB of amplification which can help to use the already owned pre
It should have a very low noise factor, due the used semiconductors
The input impedance is quite high, thus it cannot negatively influence the signal from the assembly motor+transformer.

I would like thus to build this circuit and integrate it into the mic, activating it.

But you know very well that: everything works on paper, can be a big failure in the reality

I ask your opinion about this idea/circuit and its goal.

Thank you very much in advance for your feedback and help

 

[tchgtr]

Hi,
  I don't want to discourage your DIY enthusiasm (and as far as I can tell, your circuit should work fine), but my personal opinion about ribbon mics is that if the signal you are recording/amplifying is not loud enough to be recorded/amplified with a passive ribbon mic, then perhaps another mic should be chosen.
  Adding a few more electronic bits and pieces before the signal reaches it's preamp will just add more electronic noise and artifacts, and degrade the signal a bit more on the way to it's destination, IMHO.
    I encourage you to try this circuit, and highly recommend the Nady ribbons, but wanted to make sure you were aware of the Triton Fethead, which does exactly what you want for about $100.
    I have a Nady 210, and am about to change the ribbon and transformer, but have been very happy using it for loud guitar amps as-is.
    For quieter source (violin?), I would use a nice SDC or LDC mic or two.

 

[dmp]

I really like ribbons for fiddle. I've had very good experience with the quality of sound they get going into a really good preamp in a decent room. In comparison to any cheapish condensor mic, the ribbon will get you something better in my opinion. Although maybe you would be going for a different sound than I would be!
See 0:50s of this recording I did where both a Ribbon and a SDC were set up:
http://www.youtube.com/watch?v=7sZRAjZrbJk

My gut feeling is that using a less-than-spectacular FET amplifier will lose what the ribbon had going for it in the first place. I say this because any cheap condenser with a FET amp has a distorted sound to it. Even with a cheap Chinese capule, switching to a tube gain stage reveals a huge difference and improvement in the  quality of sound. (This is my own experience and observation - NOT repeating internet chatter.)
So, try to build a really good preamp - I've used a Jensen 990 and a Neve ez1290 with ribbons on fiddle and it works great.
Then, you might want to get the ribbon in the 205 replaced with 1-2 um foil.

 

[Matador]

You should really be investigating a Cloud Lifter CL-1 as it does exactly what you need and can be had in the $125 range.  Plus, it can move from setup to setup and provide a gain boost for many other applications/microphones.

 

[Violinist]

Great, thank you to everybody you

I answer to all the messages

Hi,
  I don't want to discourage your DIY enthusiasm (and as far as I can tell, your circuit should work fine), but my personal opinion about ribbon mics is that if the signal you are recording/amplifying is not loud enough to be recorded/amplified with a passive ribbon mic, then perhaps another mic should be chosen.
  Adding a few more electronic bits and pieces before the signal reaches it's preamp will just add more electronic noise and artifacts, and degrade the signal a bit more on the way to it's destination, IMHO.
    I encourage you to try this circuit, and highly recommend the Nady ribbons, but wanted to make sure you were aware of the Triton Fethead, which does exactly what you want for about $100.
    I have a Nady 210, and am about to change the ribbon and transformer, but have been very happy using it for loud guitar amps as-is.
    For quieter source (violin?), I would use a nice SDC or LDC mic or two.

Hi and thank you for your feedback

I have a LDC and it's too brilliant for the violin. At least to my hears.
About ribbon: I heard the only one demo I was able to find on YouTube with a violin, and I really like more the ribbon for such instrument. The sound is really more sweet
Because I read also that ribbons have so little output signal and they are so sensible to the Phantom which on regularly basis I forget on  :-\ then I was thinking to this circuit.

It's true that any stage introduces noise. I fully agree. Indeed i used very low noise FET even if the trans-conductance is not so high (like the J310) thus they have less gain.

But I was thinking that: if I buy a pre with High Gain (65-70 dBs), necessarily it has more stages. And my wallet will be more light because a good pre costs """quite a bit"""  :
Low costs pres, I read here in this forum, are not good as their marketing would like to be.

Thus: a stage should be added. I thought: let's add one with less noise as possible and some dB gain. I think the first stage should gain around 25-30 dB with 30V supply. But it is on paper.
At the same time, I was thinking that: enclosing the circuit into the body of the mic, I can keep as short as possible the connections and the body will screen also the circuit itself.

Thus, the output level, from the XLR, just intuitively (I honestly just made a rough calculation) should be more acceptable for takes like violin but also voices.

I hope my thought was not too wrong :

You should really be investigating a Cloud Lifter CL-1 as it does exactly what you need and can be had in the $125 range.

Your suggestion is really interesting. I normally buy in Thomann, because to order parts from US, in Europe, we have to pay the import taxes which are not cheap.
Unfortunately Thomann has not it  :-\
If the circuit in the diagram works, perhaps costs less, especially for one piece.
But low level signals are very delicate to be threaten, that's why I have some hesitation and I need your advices

My gut feeling is that using a less-than-spectacular FET amplifier will lose what the ribbon had going for it in the first place. I say this because any cheap condenser with a FET amp has a distorted sound to it. Even with a cheap Chinese capule, switching to a tube gain stage reveals a huge difference and improvement in the  quality of sound. (This is my own experience and observation - NOT repeating internet chatter.)
So, try to build a really good preamp - I've used a Jensen 990 and a Neve ez1290 with ribbons on fiddle and it works great.
Then, you might want to get the ribbon in the 205 replaced with 1-2 um foil.

I watched your video and I really liked the sound
As well as I liked the only one video I found on youtube, when I heard the violin played with a Ribbon mic.
What you are telling here about the FET amplifier is worrying me quite, and enhance my hesitation, in relation to the pre-amp I posted.
Even if I take into consideration that the CL-1 suggested by Matador, I think is not so complex and uses FETs. I see indeed that Cloud Lifeter is making htis mic http://cloudmicrophones.com/cloud12/?page_id=231 which has FET circuitry inside

 

[emrr]

I record violin and fiddle with ribbons and 40 dB preamps all the time, I never lack gain.  I can't tell if you are sure of a gain problem, or expect one.  There are plenty of complete preamps here that can be built inexpensively, for not much more effort than what you propose.  I would do that and leave the phantom out. 

 

[Violinist]

I record violin and fiddle with ribbons and 40 dB preamps all the time, I never lack gain.  I can't tell if you are sure of a gain problem, or expect one.  There are plenty of complete preamps here that can be built inexpensively, for not much more effort than what you propose.  I would do that and leave the phantom out.

Hi

this changes completely the picture.
Yes, I'm ot sure about level problems. I just read about that in a plenty of posts. Thus I expect it.
But what you are telling in your post, changes the view. It doesn't seem that I must have the 65-75 dB gain, but I can use my normal preamp.
Please correct me if I wrong to understand.

 

[emrr]

You understand.  It is my experience that so much gain is rarely needed.  You should try the ribbon you like and see for yourself first.  I think most preamps will give 40-55 or 60, and it will be enough in most cases.

 

[tchgtr]

If you replace the ribbon in the mic with 1.8 micron ribbon, you should also get a bit more volume coming out of the mic.

 

[dmp]

I record violin and fiddle with ribbons and 40 dB preamps all the time, I never lack gain.

I think it depends on:
- how loud the performer is, of course
- how close you are micing the instrument. The further back into the room you go the more gain you will need.
- how you are monitoring. I don't need more gain for recording digitally -I don't care how low it is - but it can be a pain in the headphone mixes if it is too low.

I have a tube preamp that maxes out at ~40ish dB and it is an inconvenience, for me and others I've worked with. Can you get used to it? yes, I think so, but it is a constraint in my opinion.

 

[emrr]

40 dB max is really a constraint of antiques, most things now are at least 50-55. I mention it only because it works for me.  I seldom mic closer than 18".  I record R&B singers with ribbons who stand 3' back and can overload my recorder with a 40 dB preamp.  Not percussive yells/barks either, sustained notes. 

 

[Violinist]

I think the panorama starts to be more clear.
As far as I understood: it's necessary to distinguish what's from legends and what's the reality.
Into the reality it's necessary to focus on what really the preamps owned by each one really can do and are doing.
Then to take the decision.

Following that line, I think I really will do what suggested to all you here:

First I will buy the mic I like (discovering who sends in EU the APEX 205)
Then try it with what I have.
At this point apply all the mods you suggested here and in other topics
Try again with what I have
No one forbids to add the circuitry I posted here, to increase the output level balancing the mic electronically and really decoupling it from Phantom

This will be also another experience that certainly will increase the skill putting in highlight several things.
Thus I will.

When I will test the mic, I will produce some audioclip and pictures to post here
Thank you to everybody

 

[Winetree]

You'll have to look it up, there's a unit called the "Cloud lifter"
which will give you about 25db gain so you can use any preamp, if gains a problem.
Might also solve the phantom iso too.

 

[Violinist]

You'll have to look it up, there's a unit called the "Cloud lifter"
which will give you about 25db gain so you can use any preamp, if gains a problem.
Might also solve the phantom iso too.

Right. As I said in a previous thread, this is not available in Europe at decent price due import taxes. And it costs much more than the one in the diagram.
the one in my opening thread, will cost to me from 10 till 15 euro

 

[ricardo]

http://www.groupdiy.com/index.php?topic=5743.80 is PRR's version.  I've got a slightly quieter one on my Yahoo MicBuilders Files directory.

Don't think mine is worth it unless you have a 30-50R nominal ribbon.

For the usual 200-600R ribbon, probably better to make a dedicated Ribbon preamp w/o P48.  I describe how to modify a M-Audio DMP3 (<$100 on eBay) for very low noise and high gain.

 

[Violinist]

About phantom power, I got this video few minutes ago.

http://www.youtube.com/watch?v=YmHgPbSqhAE

I think it's valid if the ribbon is connected only to the transformer and the transformer is connected to 2 and 3 without other interactions.
Thus I think the simple way is to check it into a mic and to adjust the mic on this sense.

For ribbons mic: I got this webpage too: http://recordinghacks.com/2008/11/01/chinese-ribbon-microphone-designs/

If it's true that all these ribbon mics are the same, then if I get the Thomann one, I will spend much less, without any tax import issue, with just a different color if compared with the APEX 205.
At this point I will make modifications etc

@Ricardo
I've read the whole thread on the address you gave me. I think I missed the modification to the M-Audio DMP3 which I would like to read about.
Always inherent this pre: I looked for it several times, but if I'm not wrong, unfortunately it seems it is not more in production.

 

[ricardo]

I've read the whole thread on the address you gave me. I think I missed the modification to the M-Audio DMP3 which I would like to read about.

The mods to DMP3 are in my Yahoo MicBuilders Files directory.  You have to join.

Getting rid of evil P48V helps with noise.  You need every dB of noise performance with ribbons.

2nd hand DMP3 can be found for $50 on eBay.

 

[Violinist]

I had to create a new account. This summer my PC crashed and I lost everything.
Now I asked to join to your group

 

[vanakaru]

I got Triton Fethead for my Oktava ML51(original pre removed and toroid rewired). I bought the one with -6dB/Oktave High-pass Filter

* Low noise Class A JFet amplifier
* 20dB amplification
* Lots of headroom
* freq. response 10Hz - 100 kHz (+/- 1dB)
* Z-in 22kOhm
* 18-48 V phantom power

I am not too happy with it. Maybe the filter is what I do not like.
I have experimented with my mic using M Audio Audio Buddy. It is rather noisy box, but at least it gave me the idea how the Oktava Sounds. With FetHead the sound is not so rich any more. Also it introduces it's own set of noises - mostly hum.
Here is a schematics and I wonder if I can remove the filter. But I am totally illiterate about the works of electronics. So if you can tell me what parts are the filter ones.

 

[gyraf]

Here is a schematics and I wonder if I can remove the filter.

No filter in that schematic. And

* freq. response 10Hz - 100 kHz (+/- 1dB)

..points towards no filter, doesn't it?

Jakob E.