Tube vs solid state microphones

[Gus]

I have been thinking about what people believe is the tube sound?

Lets take transformer out tube and solid state microphones

Something I want to measure is how much of the tube sound is microphonics

This has been brought up before at this site

You can build a solid state to mimic tubes to an extent so do we need to add a microphonic pick device(s) to add to the sound of the solid state to get the "tube sound"?

I have ideas of what I will build when I have time to test this.

Also think about guitar amps
All the tubes vibrating in a combo or a head on a cab.

I have even heard a difference with the type of tone cap used in a guitar when the guitar is in a sound field at stage volume. A big microphonic class 2 or 3?(not sure what is was) ceramic sounded the best in one guitar when the cap was touching the body wood.

 

[gyraf]

..there was a (AES?) paper from late-60'es speculating about the u47 sound being from notoriously microphonic tubes. Havent been able to reconstruct exactly what article, lost the article access with my daytime job..

The most beautifully sounding tube I came across while going through many-many tube types for mic head amps was of a type I later abandoned because it was literally impossible to find one that was not heavily microphonic. Only many years later did I realize that this was probably what subjectively sounded good..

Bruel&kjaer did a microphone sometime early-90'es that came both in a tube and a FET version. They were pretty proud of the fact that noone could tell the difference..
..sigh..

Piezo in drain of head-amp FET anyone..?

/Jakob E.

 

[kingkorg]

Fwiw i love my Frankentube with 6418 and a version of C12 (phantom powered) with russian  1J24B (1Ж24Б) also 1.1v filament, also microphonic.

 

[craigmorris74]

I think this idea is fascinating. It would be could to find that a good chunk of the U47 sounds was a "flaw"! I don't have the knowledge to contribute for the design, but I'm willing to try things out and see how they sound.

 

[Gus]

..there was a (AES?) paper from late-60'es speculating about the u47 sound being from notoriously microphonic tubes. Havent been able to reconstruct exactly what article, lost the article access with my daytime job..

The most beautifully sounding tube I came across while going through many-many tube types for mic head amps was of a type I later abandoned because it was literally impossible to find one that was not heavily microphonic. Only many years later did I realize that this was probably what subjectively sounded good..

Bruel&kjaer did a microphone sometime early-90'es that came both in a tube and a FET version. They were pretty proud of the fact that noone could tell the difference..
..sigh..

Piezo in drain of head-amp FET anyone..?

/Jakob E.

I think the drain resistor might load the piezo too much but maybe it would work.
It might need a JFET follower for the piezo to set the level correctly and mix it back in after the capsule gain stage, an invert switch or EQ might be needed as well

 

[Winston OBoogie]

I've been playing with some tubes that measure well but are known to be microphonic.
This is in mic amp or line amp duty.

One russian tube has a cluster of microphonics that resonate about 3K to 4.5K, and a few lower ones  around 500 Hz.  It sounds glorious though.
Same with the D3a in triode mode although that one is higher gain and is also now well known and thus expensive.

At first I was bothered because I see folks complaining about these tubes that are easily excited by giving them a flick with your finger.
But then I realized that I don't usually flick my tubes while they're being used so I just settled for adding mass and using a damped/floating socket.  A couple of silicon rings on the glass helps a little, not those expensive dampers they sell for $25 though, these were about $0.50 each. 

I have no opinion on if a microphonic VF14 is part of the U47 sound.  I'd like to read the paper though if you come across is Jakob.   

 

[Gus]

Jakob

Your post about this in another thread is one of the reasons I started this thread.

I tend to like solid state microphones over "standard" tube microphone circuits.

I built a microphone using a circuit like a ELA M250 with a real 6072 tube and I built a solid state circuit to replace the tube with the same plate resistor current it sounds more "tight" with the solid state.
I can understand the use of both solid state and tube microphones

5840s and EF86s tend to have close specs as triodes and are different sizes but do they sound the same?

 

[analogguru]

An application for MEMS.

 

[earlfsmith]

church 47 was tube was replaced in the later versions. Something to think about

 

[evil grill]

I've been playing with some tubes that measure well but are known to be microphonic.
This is in mic amp or line amp duty.

One russian tube has a cluster of microphonics that resonate about 3K to 4.5K, and a few lower ones  around 500 Hz.  It sounds glorious though.
Same with the D3a in triode mode although that one is higher gain and is also now well known and thus expensive.

At first I was bothered because I see folks complaining about these tubes that are easily excited by giving them a flick with your finger.
But then I realized that I don't usually flick my tubes while they're being used so I just settled for adding mass and using a damped/floating socket.  A couple of silicon rings on the glass helps a little, not those expensive dampers they sell for $25 though, these were about $0.50 each. 

I have no opinion on if a microphonic VF14 is part of the U47 sound.  I'd like to read the paper though if you come across is Jakob. 

Where can one find the cheap silicon rings?

 

[Winston OBoogie]

Where can one find the cheap silicon rings?

Hiya,
I got them on Ebay.  They came from China and were sold in batches of 20.  No more than 5 Euro including shipping for the 20.  I used 3 per valve.
Here's one link, not where I got them I don't believe, but there are quite a few places in China that sell 'em
https://www.ebay.co.uk/itm/174211035335

The microphonic tubes seem to either be types that don't have good internal support, or the opposite where they're frame grid types with 3 X mica supports.
Best is to add mass and float the sub assembly somehow.  I used knicker elastic which is cheap - not my idea, I got the tip from a Morgan Jones book.   

 

[Winston OBoogie]

Alternatively, Steve Bench has tried using a combination of visco type material supporting the tube sockets, tube dampers, and a foam material called isoloss.  He achieved 30dB reduction in microphonics all told.  Down the page here:
http://diyaudioprojects.com/mirror/members.aol.com/sbench101/

 

[evil grill]

Alternatively, Steve Bench has tried using a combination of visco type material supporting the tube sockets, tube dampers, and a foam material called isoloss.  He achieved 30dB reduction in microphonics all told.  Down the page here:
http://diyaudioprojects.com/mirror/members.aol.com/sbench101/

Great! Thanx!

 

[bockaudio]

church 47 was tube was replaced in the later versions. Something to think about

Can you clarify your statement?

 

[Gus]

Posted this picture this in another thread two tube voltage solid state circuits. The circuit on the left will be changed. I have another tube voltage circuit built and another tube voltage circuit idea started as well as two phantom powered circuits that have some part of the "tube sound" however, I do not have the microphonic part that I am guessing sometimes seems to add something to the sound

 

[Gus]

One of the things that I am still working on with the solid state versions I built so far is in the lower frequencies.
I have a test box on the list of things to build. I would then sweep the tube microphones without a capsule using a non(very low) microphonic cap for the capsule to do some tests.

Two links

https://www.pearl-hifi.com/06_Lit_A.../2080_Measurement_of_Microphony_in_Valves.pdf
https://www.effectrode.com/knowledg...n-of-microphony-and-methods-of-investigation/

 

[Gus]

Started a different new circuit build with parts I had. Thinking about what I like about JFETS and Tubes.
140VDC from a China PS
Will be multi-pattern when I finish
The DC voltages in the design sim matched in the build
On the bench I could drive the input to 2V P to P before it started to bend the waveform.
I will try a BV11 like with this circuit

Also drew a solid state m49 116VDC 120VDC B+ like microphone circuit I will make a sim of.
EDIT made the M49 sim

Anyone else working on tube voltage solid state microphone circuits?

 

[Marik]

Gus,

The only reference I can think of is Ethan Winer’s U47 SS mod:

https://ethanwiner.com/U47-FET.html
What kind of current through the jFet are you thinking? I assume some .2–.3mA then a B+ DC/DC converter might be a more economical approach than external PSU.

Does the sim allow you to see what happens to noise?

Best, M

 

[Khron]

For sub-mA currents, even a linear regulator (discrete, of course) might suffice.

 

[Gus]

Gus,

The only reference I can think of is Ethan Winer’s U47 SS mod:

https://ethanwiner.com/U47-FET.html
What kind of current through the jFet are you thinking? I assume some .2–.3mA then a B+ DC/DC converter might be a more economical approach than external PSU.

Does the sim allow you to see what happens to noise?

Best, M

IMO the linked mod has a big design flaw. The SPA phantom powered mod that was posted at this forum is most likely better.

The JFET part is not working hard at all, ID is lower that what you posted.

The point of this is to build it and try it out also it can be subbed in for a tube in some microphones.

I have solid state circuits drawn up, simmed and some built that can run at C800G and down to u47 voltages and drive BV8, BV11 type transformers.

Also finished the solid state M49 sim idea now I need to find a body to build it in. I have nice BV11 type transformer Oliver wound for me years ago when AMI was in Seattle I believe.

A little off topic, I wonder how many people realize the 49 has a HPF, do certain circuit adjusters remove it?