Gus

Tube vs solid state microphones
« on: February 20, 2021, 08:57:43 AM »
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

Re: Tube vs solid state microphones
« Reply #1 on: February 20, 2021, 10:50:48 AM »
..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.
..note to self: don't let Harman run your company..

kingkorg

Re: Tube vs solid state microphones
« Reply #2 on: February 20, 2021, 11:02:22 AM »
Fwiw i love my Frankentube with 6418 and a version of C12 (phantom powered) with russian  1J24B (1Ж24Б) also 1.1v filament, also microphonic.
« Last Edit: February 20, 2021, 01:09:12 PM by kingkorg »

craigmorris74

Re: Tube vs solid state microphones
« Reply #3 on: February 20, 2021, 12:56:46 PM »
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

Re: Tube vs solid state microphones
« Reply #4 on: February 20, 2021, 05:09:22 PM »
..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

Re: Tube vs solid state microphones
« Reply #5 on: February 20, 2021, 05:25:08 PM »
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.   
D. J. H.

The standard way to reduce much of the noise and distortion in audio gear in 1955 was to have a couple of beers.
 Anything else was too fiddlesome and too expensive.

Gus

Re: Tube vs solid state microphones
« Reply #6 on: February 20, 2021, 08:02:20 PM »
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?

« Last Edit: February 20, 2021, 08:14:56 PM by Gus »

analogguru

Re: Tube vs solid state microphones
« Reply #7 on: February 21, 2021, 04:03:31 AM »
An application for MEMS.

Re: Tube vs solid state microphones
« Reply #8 on: February 21, 2021, 04:51:59 AM »
church 47 was tube was replaced in the later versions. Something to think about

evil grill

Re: Tube vs solid state microphones
« Reply #9 on: February 22, 2021, 02:52:37 AM »
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?


Re: Tube vs solid state microphones
« Reply #10 on: February 22, 2021, 04:19:41 AM »
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.   
D. J. H.

The standard way to reduce much of the noise and distortion in audio gear in 1955 was to have a couple of beers.
 Anything else was too fiddlesome and too expensive.

Re: Tube vs solid state microphones
« Reply #11 on: February 22, 2021, 04:31:01 AM »
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/
D. J. H.

The standard way to reduce much of the noise and distortion in audio gear in 1955 was to have a couple of beers.
 Anything else was too fiddlesome and too expensive.

evil grill

Re: Tube vs solid state microphones
« Reply #12 on: February 22, 2021, 04:36:55 AM »
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

Re: Tube vs solid state microphones
« Reply #13 on: March 24, 2021, 06:02:38 PM »
church 47 was tube was replaced in the later versions. Something to think about
Can you clarify your statement?


 

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