Tube Ribbon Mic Schematic

[commanderberti]

any schematics ... ? thanks for all infos..

 

[soliloqueen]

an active ribbon mic with a tube amplification circuit? not aware of any public schematics. I think the 122V has 2 transformers.

 

[rock soderstrom]

David Royers 122V is a triode wired 5840 cathode follower into a Jensen low step down transformer. Check the country boys tube mic or his SDC mod for further info.

I think this is a good idea... not really

 

[rock soderstrom]

I think the 122V has 2 transformers.

I've never seen the inside of this mic, does that mean there's a transformer between the ribbon and the grid? I guess so...

Edit: After a little more thought on this topic, I have to correct my assessment from my first post. The advantages of an active ribbon microphone are there, but less than I originally thought. Ribbons do not go particularly well with tubes because of their low impedance.

Still exciting, I'll have to give it a try.

 

[commanderberti]

first test prototype.. works great, next steps follow..

 

[rock soderstrom]

I'm no expert, but the whole thing would make more sense if you could save the transformer in front of the tube.

Maybe try a grouded grid amp and feed the ribbon directly into the cathode??

 

[commanderberti]

I'm no expert, but the whole thing would make more sense if you could save the transformer in front of the tube.

Maybe try a grouded grid amp and feed the ribbon directly into the cathode??

The transformer makes sense, it's also a sound element if it's good.. basically it's a tube preamp that's already sitting directly in the mic.. the setup here is just for testing with XLR.. of course I have the polarization voltage gone (r4) and am now experimenting with C4 (currently 1uf) and 500k grid on gnd.. sounds good.. but I'm not satisfied yet.. I'll test it with the Fame Audio VRM-26 as soon as the day comes If successful, merge a finished micro

 

[rock soderstrom]

The transformer makes sense, it's also a sound element if it's good.. basically it's a tube preamp that's already sitting directly in the mic.. the setup here is just for testing with XLR.. of course I have the polarization voltage gone (r4) and am now experimenting with C4 (currently 1uf) and 500k grid on gnd.. sounds good.

I don't want to discourage you from experimenting. On the contrary, I am watching the thread with interest.

If I understand correctly, your signal path ATM is ribbon - step up transformer - 12AX7 headamp - step down transformer.

Your passive ribbon mic has an estimated output impedance of 200-300 ohms, your input impedance is currently 500K, a mismatch. You actually need a third transformer or another one with a much higher step up factor after the ribbon.

I will try my luck with a different type of circuit.

 

[commanderberti]

Ich möchte Sie nicht vom Experimentieren abhalten. Im Gegenteil, ich beobachte den Thread mit Interesse. y)

Wenn ich es richtig verstehe, ist Ihr Signalpfad-ATM Bändchen - Aufwärtstransformator - 12AX7-Kopfverstärker - Abwärtstransformator.

Ihr passives Bändchenmikrofon hat eine geschätzte Ausgangsimpedanz von 200-300 Ohm, Ihre Eingangsimpedanz beträgt derzeit 500 K, eine Diskrepanz. Eigentlich braucht man einen dritten Transformator oder einen anderen mit einem viel höheren Step-Up-Faktor nach dem Farbband.:kühl:

Ich werde mein Glück mit einer anderen Art von Strecke versuchen. Das ist

I don't want to discourage you from experimenting. On the contrary, I am watching the thread with interest.

If I understand correctly, your signal path ATM is ribbon - step up transformer - 12AX7 headamp - step down transformer.

Your passive ribbon mic has an estimated output impedance of 200-300 ohms, your input impedance is currently 500K, a mismatch. You actually need a third transformer or another one with a much higher step up factor after the ribbon.

I will try my luck with a different type of circuit.

Not quite, at this point an ohmic power adjustment is not the problem or the goal, it's about voltage amplification. If I used a transformer with a much higher ohmic output.. I would have to attenuate again in front of the tube.. the 500k is actually only so that the c8 pass can work correctly...

 

[Khron]

Your passive ribbon mic has an estimated output impedance of 200-300 ohms, your input impedance is currently 500K, a mismatch. You actually need a third transformer or another one with a much higher step up factor after the ribbon.

... Or just a lower-than-500k grid-to-ground resistor..?

 

[commanderberti]

... Or just a lower-than-500k grid-to-ground resistor..?

yes

 

[kingkorg]

The transformer makes sense, it's also a sound element if it's good.. basically it's a tube preamp that's already sitting directly in the mic.. the setup here is just for testing with XLR.. of course I have the polarization voltage gone (r4) and am now experimenting with C4 (currently 1uf) and 500k grid on gnd.. sounds good.. but I'm not satisfied yet.. I'll test it with the Fame Audio VRM-26 as soon as the day comes If successful, merge a finished micro

Make sure you check the THD/clipping levels with a beast like this. It might sound great on low spl, but what happens at higher levels?

 

[Khron]

Make sure you check the THD/clipping levels with a beast like this. It might sound great on low spl, but what happens at higher levels?

Well, a passive ribbon won't have huge output to begin with, but as we all know, assumption is the mother of all f**k-ups... So testing would of course clear things up in a jiffy.

 

[kingkorg]

Well, a passive ribbon won't have huge output to begin with, but as we all know, assumption is the mother of all f**k-ups... So testing would of course clear things up in a jiffy.

Sure, don't know, just whenever i "activated" a ribbon, harmonics creeped up at some point.

 

[Tim Campbell]

Wouldn't this just be simpler to build a tube preamp optimized for ribbon mics and use your mic in front of it?

 

[rock soderstrom]

Wouldn't this just be simpler to build a tube preamp optimized for ribbon mics and use your mic in front of it?

I had similar thoughts yesterday. From my point of view, it only makes sense if you can (however) save on the transformers and the sound still remains good.

One of my ideas is to use the following, then customised circuit. My idea would be to replace the step-up transformer after the ribbon with that and the output CF would allow the use of cheaper low step-down transformers.

The question remains, does the ribbon like that and what about the noise? The amplifying V1 triode is probably noisier than the transformer after the ribbon.

Any opinions?

All schematics are from:

https://www.tubecad.com/2014/11/blog0312.htm

 

[commanderberti]

Wouldn't this just be simpler to build a tube preamp optimized for ribbon mics and use your mic in front of it?

yes of corse, but this is a micmodding "sport" project.. , all this mics ar unique.. in the world.. capsules from fet mics on tube mics..

 

[Recording Engineer]

This is all really interesting. We have one at the studio. Honestly, it truly is the only Royer ribbon mic I like. It definitely is a highly-refined sound.

 

[rock soderstrom]

This is all really interesting. We have one at the studio. Honestly, it truly is the only Royer ribbon mic I like. It definitely is a highly-refined sound.

Cool, if that's not too much to ask. A few gutshots would be great!

 

[rock soderstrom]

The question remains, does the ribbon like that and what about the noise? The amplifying V1 triode is probably noisier than the transformer after the ribbon.

After a little more thought, I think that speaks against my idea. You can't beat a 1:35 transformer in terms of noise. No matter how good the tube is.