Active ribbon-mic

> why my offset adjustment dun wuk.

3K-100r-3K offers a 1.0164:1 trim. Small, but should be visible on a good meter.

It will NOT work to balance collector voltages if the Phantomed mike input is constructed as a CT transformer with 3K4 to the CT.

PRR said:

> why my offset adjustment dun wuk.

3K-100r-3K offers a 1.0164:1 trim. Small, but should be visible on a good meter.

Click to expand...

That's sorta what I calculated.  My breadboarding is complicated by my !*??% MOTU Traveler which gives P39V instead of P48V.

Hi all,

I'd like to try building the phantom-powered BJT version from the schematic PRR posted on page 5...


Could someone set me straight on the minimum capacitor voltage ratings here?

Thanks!

3V

Hey Guys: I have a fair number of LM394's in the cans. P.M. me if interested they will be half the price quoted PRR by Digikey.

In the discussion about Active Ribbon circuits, I make the point that for 'normal' ribbons with a 200R nominal Zo, it would be more sensible to make a dedicated Ribbon Preamp using some of the excellent devices like THAT1510 or TI INA163.

Or maybe modify an existing preamp into this, reducing noise & increasing gain rather along the lines of a special order Millenia Media HV3 or AEA TRP.

I've put a note describing exactly this on M-Audio DMP3 (<$100 on eBay)

RibbonDMP3.doc  in MicBuilders\Files\Ricardo\ActiveRibbon

You have to join the Yahoo Group.

My thanks to Zunda for being the trial builder.

Comments please, especially from anyone who wants to try this.

My Active Ribbon circuit is only worthwhile if you have a nominal 30-50R ribbon like the original STC4038

Hello Ricardo,

Thanks for that - I was motivated to dig out my yahoo password and have a look! It made nice reading for a Monday morning. I may give it a go if I can find a DMP3.

The mods look interesting, and am now wondering if I can squeeze a 24 position rotary in there.

A small pedantic thing: a couple of times you use the phrase 'solder across'... as in  "1u5 inductors directly across each 47R". By this I assume you mean in parallel with. I could imagine a less experienced reader dinding it ambiguous.

I had a quick look on ebay for the m-audio box, but there seem to be none available right now. You may have made them popular!

Keep up the good work!

Stewart

Hello,

I would like to build up a couple of these "pre-preamps" for my own DIY Ribbon mics.

Can someone please explain the bias connections in PRR's "no-tran-ribbon-boost" schematic to me, and how I would connect these up in practice?  I have diy Green-pres and DIY REDD47 preamps with 48v phantom to use (with phantom power), but am interested in trying battery powered dc too.

Does anyone have links to layouts/wiring diagrams ?  I have trawled through the relevant threads and searched extensively but cannot find any physical build info expect for a stripboard layout on one posting, which didn't have off-board connections identified.

Any help greatly appreciated.

Many thanks
Pete

I have 3 Shure SM59 mics that are very low output.  I dug up this thread and found PRR's no transformer mic booster.    I got lucky and found some old Motorola 2N4401's in my parts bin so I decided to give it a rip.    I had an old AKG B46E 9v to  ?? phantom power supply I have never used in 25 years.  Its about the same size as the Cloudlifter and has all the connections I needed.  Removed the original parts and mounted a vero board version of the mic booster.  So far it appears to work well.    I love it when I can put together something useful with existing stuff and $0 cost involved!

Now just for the fun of it, I might have to build Brad's FET impedance converter version for a bit more gain.  If only I had another AKG B46E laying around....

Regards,
Jeff

I built a few of these, and they've been working great for me so far.  I used a variety of transistors between them, and tested them for total gain, average noise increase (dependent on preamp used and gain at the preamp), and noise increase per db of gain.


Preamps used were the pre's in my Fireface 800, Digidesign Pre, and JoeMeek TwinQ.  I was as methodical as possible, using the same cables for each test, terminating the input with a 150ohm resistor, and reading LUFS over 15 seconds.  I matched transistor and resistor pairs per unit, and used 1% resistors elsewhere.

By no means should this be taken as gospel, but as a rough indication of performance.

PeteC said:

Hello,

I would like to build up a couple of these "pre-preamps" for my own DIY Ribbon mics.

Can someone please explain the bias connections in PRR's "no-tran-ribbon-boost" schematic to me, and how I would connect these up in practice?  I have diy Green-pres and DIY REDD47 preamps with 48v phantom to use (with phantom power), but am interested in trying battery powered dc too.

Does anyone have links to layouts/wiring diagrams ?  I have trawled through the relevant threads and searched extensively but cannot find any physical build info expect for a stripboard layout on one posting, which didn't have off-board connections identified.

Any help greatly appreciated.

Many thanks
Pete

Click to expand...

Hi there

I 'd be intrested too

Many thanks

PeteC said:

Does anyone have links to layouts/wiring diagrams ?  I have trawled through the relevant threads and searched extensively but cannot find any physical build info expect for a stripboard layout on one posting, which didn't have off-board connections identified.

Click to expand...

Ribbon mic is connected between In+ and In-, Out+ goes to pin 2 of XLR, Out- goes to Pin 3, Ov goes to pin1, all Bias points are connected together.

Old Thread that seems to predate the present tendencies....

Theres a lot of products in the market at the moment, did it all started in this thread?

Whoops said:

Old Thread that seems to predate the present tendencies....

Theres a lot of products in the market at the moment, did it all started in this thread?

Click to expand...

No. FetHead and Cloudlifter started about 10 years ago. I guess the reason is the availabiity of inexpensive ribbon mics, that give rather mitigated performance when used as a replacement for a condenser mic or a good quality dynamic.
Out of curiosity I bought a Thomann ribbon mic and found it utterly unusable; I investigated and found the actual impedance was 2500 ohms. I paired it with a FetHead and it became usable, although it is actually sitting in the cupboard and rarely sees the light of day.

abbey road d enfer said:

No. FetHead and Cloudlifter started about 10 years ago.

Click to expand...

Hi Abbey,
this thread started 14 years ago.

It was also 14 years in 2005 ago that PRR posted his circuit in this thread.

In 2005 there was no Fethead and it was also before the boom of cheap Ribbon Mics.

Whoops said:

Hi Abbey,
this thread started 14 years ago.

It was also 14 years in 2005 ago that PRR posted his circuit in this thread.

In 2005 there was no Fethead and it was also before the boom of cheap Ribbon Mics.

Click to expand...

Please check answer #46 and 48, dated 2005, that mentions cheap ribbon mics from Nady, Thomann et al.

before the "Boom" of cheap Ribbon Mics

I will build 2 with the PRR circuit to try out on some Ribbon mics.

After so many years that PRR showed the circuit is there anyone with some tips or improvments  over the original circuit?
Any advise?

Thank you so much

Whoops said:

Old Thread that seems to predate the present tendencies....

Theres a lot of products in the market at the moment, did it all started in this thread?

Click to expand...

My feeling is, that this forum (and some others of course) did actually give a lot of inspiration that helped spark new companies and busines models in the pro audio industry. Start from chinese diy kits, include 'new developments' like this one here in the thread, don't even stop at Behringer doing 1176s, LA2As, Pulteks and other stuff under the more reputable brand 'Klark Teknik' or new companies like 'Golden Age' with their clones. This here is a good example why I believe that it has become a lot less likely that someone might actally post a good unique idea or attemp to clone some rarities here. 

Michael

Michael Tibes said:

My feeling is, that this forum (and some others of course) did actually give a lot of inspiration that helped spark new companies and busines models in the pro audio industry.

Click to expand...

Recognized, indeed several cases where shared ideas from here (and as Michael said, from other places as well) were converted into cash by others.
It's a free world, but also a bit grey sometimes w.r.t. what's fair to use and what's less elegant.