A Pre for your Ribbons

http://www.twin-x.com/groupdiy/albums/userpics/RibbonPre%7E0.JPG
(Corrected)
This will give you all the gain you need for your ribbon mics.
A tetrode symbol is used, but the EF86 is a pentode, unfortunately my stimulator will only model it with a tetrode symbol. Ok?

analag

Very nice. :thumb:

Hmm....partition noise.

Have you built it yet?

Have you simulated it yet?

What is the max. gain available?

Cheers,

Roddy

Perhaps I'm misinterpreting the schematic, but it looks like, in the second stage, the output of the first tube's plate (inverted polarity) goes through a non-inverting follower and comes out still inverted. Feeding that back to the cathode of the first tube, rather than the grid, would constitute positive feedback, no?

Peace,
Paul

Good timing, I am going to be needing something like this in not to long. This might be worth a try, although not sure how I feel about EF86s. It is a nice tube and all, but gettng abit on the expensive side, maybe see what a 6SJ7 thinks about the circuit.

adam

[quote author="pstamler"]Perhaps I'm misinterpreting the schematic, but it looks like, in the second stage, the output of the first tube's plate (inverted polarity) goes through a non-inverting follower and comes out still inverted. Feeding that back to the cathode of the first tube, rather than the grid, would constitute positive feedback, no?

Peace,
Paul[/quote]

It is two inverting stages....the first stage flips the polarity 180 degrees out of phase and the second stage flips it back 180 degrees and back in phase. No feedback is used in the first gain, providing raw gain. The second stage is somewhat tamed with the omitted cathode bypass cap and current feedback from the White CF.

[quote author="adamasd"]Good timing, I am going to be needing something like this in not to long. This might be worth a try, although not sure how I feel about EF86s. It is a nice tube and all, but gettng abit on the expensive side, maybe see what a 6SJ7 thinks about the circuit.

adam[/quote]

A 6SJ7 should work just fine, you might want to tweak the value of the screen resistors though.

analag

[quote author="rodabod"]Have you simulated it yet?

What is the max. gain available?

Cheers,

Roddy[/quote]

Gain is very, very high. Much more than the regular 70dB thus a Ribbon specific mic pre.

I built a pentode cascading into a triode, not a pentode cascading into a pentode as I did not need that much gain at the time.

analag

sometime last july i printed this out and found it just now while organizing papers and stuff into a new filing cabinet..... i've been thinking of doing something very similar to this lately, as i have the tubes, and the input transformers as well. and some outputs come to think of it.

i think i may just need a few caps, and a power transformer.... also will have to figure out if any of the resistors need to be higher than 1/2 watt.

analag, with your updating and re-working of gear in your place, has this one held up to the tests of time so far?

[quote author="enthalpystudios"]
analag, with your updating and re-working of gear in your place, has this one held up to the tests of time so far?[/quote]

All the resistors can be half watt, but my preference is one watt in the B+ and plate circuit. I also favor carbon film to metal film, my ears like the sound of it.
All my tube gear are functioning well, I wish one would break so I could have a reason to get into it, oh well.
Lately I have been messing around with discrete sandstate, I'm actually making a high voltage Opamp as we speak +/-100V.

analag

I canna' find it .... must have been lost when Group DIY went down .... Can anyone point me towards this schematic?

[quote author="mikka"]I canna' find it .... must have been lost when Group DIY went down .... Can anyone point me towards this schematic?[/quote]

Try it now.

analag

:thumb: Thanks .....

Looks nice....... Damn..... another for my "to do" list .... Kind of you to share ...

EF86 no problem here, have these around.
Any suggestions perhaps for an 6SN7 alternative ?
(preferably starting with ECC.. or PCC.. :wink: )

12SN7..... :green:

ECC 33/34/35 ..... if you're rich or lucky

5692 .....

VT-231 .......

12SX7 .... specially selected

The 6SN7 is basically two 6J5 triodes in one glass envelope....(Wikipedia) Are these just around the corner from you?
http://cgi.ebay.com/4x-NEW-6J5-USA_W0QQitemZ320091134585QQcategoryZ7275QQssPageNameZWDVWQQrdZ1QQcmdZViewItem

[quote author="mikka"]12SN7..... :green:

ECC 33/34/35 ..... if you're rich or lucky

5692 .....

VT-231 .......

12SX7 .... specially selected

[/quote]

Hmm, thanks :?
:wink:

but then:

The 6SN7 is basically two 6J5 triodes in one glass envelope....(Wikipedia)
Are these just around the corner from you?
http://cgi.ebay.com/4x-NEW-6J5-USA_W0QQitemZ320091134585QQcategoryZ7275QQssPageNameZWDVWQQrdZ1QQcmdZViewItem

Click to expand...

Whoa, that's almost spooky! That's just 34km! Thanks :thumb:

thanks for the respond! i'm going to use cinemag input iron with guavatones relay boards for switching options, and some lundahl 2:1 outputs....

the cinemag is 150/600:15K...... and I'm also about done getting parts for nyd's MILA, for which I've got some utc o-1 like he used in the one bottle....

question is, not that it *has* to be used for ribbons, but would i possibly be better off using the o-1's for this pre, since it has a 50ohm tap on the input transformer primary (as well as 250 and 600)? secondary is 50k

i'm sure both circuits would sound good with either set of transformers, but i'm thinking the 50/250/600 options would be nice to have for ribbons, especially with the stepup from 50:50k

[quote author="analag"]http://www.twin-x.com/groupdiy/albums/userpics/RibbonPre.JPG

This will give you all the gain you need for your ribbon mics.
A tetrode symbol is used, but the EF86 is a pentode, unfortunately my stimulator will only model it with a tetrode symbol. Ok?

analag[/quote]
Could you tell a bit about the thoughts for doing the circuit like this ?

Or is it just simply "Ah, rrrrribbons, need gain, grab pentodes" ?

Cheers,

Peter

If you can get by with a little lower secondary http://cinemag.biz/mic_input/CMMI-7C.pdf has a 50 ohm tap.

Steve

i already have a small handful of o-1's is why i ask, maybe i'm wrong about 50 ohm taps..... for some reason i thought that it was a good move to bridge the very very low impedance of most ribbon mics.