DIY Tube Mic project

[Emmathom]

Some people just like the physical shape of the glass envelope of vacuum-tubes, along with the soft, warm glow that emanates from within them!!! What's there -- NOT -- to love about vacuum-tubes.....despite all of their inefficiencies???

Inefficiencies ??? could you be more precise please ?

 

[micolas]

Inefficiencies ??? could you be more precise please ?

It is about energy inefficiency, electrical yeld, high consumption, a lot of dissipated heat, heavy equipment, etc.

 

[MidnightArrakis]

It is about energy inefficiency, electrical yeld, high consumption, a lot of dissipated heat, heavy equipment, etc.

What he said.....especially about the etc., etc., etc., etc., etc., etc., etc., etc., etc., etc., etc., etc., etc., etc., etc., etc., part!!!



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[Emmathom]

What he said.....especially about the etc., etc., etc., etc., etc., etc., etc., etc., etc., etc., etc., etc., etc., etc., etc., etc., part!!!

/

I understood what you said from the begining but I wanted you to be more clear...
BTW why write your arguments in bold ?
Your style is a bit agressive for me - my POV -

PS : if you don't like tubes that's your right, but don't disgust others. Thank you

 

[MidnightArrakis]

I understood what you said from the begining but I wanted you to be more clear...
BTW why write your arguments in bold ?
Your style is a bit agressive for me - my POV -

PS : if you don't like tubes that's your right, but don't disgust others. Thank you

[if you don't like tubes that's your right, but don't disgust others] -- YOU'VE GOT BOTH ME AND MY ATTITUDE ALL COMPLETELY WRONG, Buddy!!! -- >> I LOVE VACUUM-TUBES!!! << and actually prefer them to all of the new-fangled digital stuff!!! I've got vacuum-tubed audio amplifiers in my radio-production studio, some old vacuum-tube preamps and I've even still got an old vacuum-tube AM-transmitter that some guy had built for me back in the late-60's!!! So.....calm down, OK???

/

 

[Migs 31]

@MidnightArrakis
Your description of valves/tubes strangely reminds me of my woman:
“Some people just like the physical shape “
Even her inner being: “along with the soft, warm glow that emanates from within “
Absolutely right: “What's there -- NOT -- to love about her”

Yes I’m sure there’s better out there “....despite all of her inefficiencies???”
(She allways gets lost even with Google maps).

But just like a good Fender Twin or a Marshall JCM 900... there’s something about Her, that I cannot clearly identify or quantify and I just love it. I rather stick with Her (valves) I would miss Her if She was not around.
M

PS: Gentlemen take it easy, Text messages, e-mails and GDIY posts DO NOT transmit accurately our real human emotions & personalities. Don’t get too offended please.

 

[Emmathom]

[if you don't like tubes that's your right, but don't disgust others] -- YOU'VE GOT BOTH ME AND MY ATTITUDE ALL COMPLETELY WRONG, Buddy!!! -- >> I LOVE VACUUM-TUBES!!! << and actually prefer them to all of the new-fangled digital stuff!!! I've got vacuum-tubed audio amplifiers in my radio-production studio, some old vacuum-tube preamps and I've even still got an old vacuum-tube AM-transmitter that some guy had built for me back in the late-60's!!! So.....calm down, OK???

/

Ok english is not my native language so I thought you came in "sarcastic"...

 

[Emmathom]

This mic is concerned by this new thread (sound samples included):
https://groupdiy.com/threads/mics-blind-test.87738/page-4

 

[Emmathom]

Hi guys
I will come back in a while with modifications on these 6AK5 mics (I'm building a second one for fun) : capsule, capacitor, output transformer... and also picts of the metal work process to fit the t.bone SC440 USB (body donor) with XLR connector and some more infos...

Pict of the PSU : on the back pannel is the main switch (and heater on). On the front pannel the led indicates that main power (and heater) is ON and the led-lighted-switch activates HT (I know that the cooling holes [for LM137 heater heatsink] on the top are not "nice" > will do better for the second one). The enclosure is almosy full...

See ya

 

[Emmathom]

PSU-2 buit and tested = 100% OK
Tr 230 - 2*18v @ 8VA delivers a little less voltage (120v) than the 10VA (130v) with same diodes & capacitors values but that's fine to reach 100v@3,5mA.
30Ω load on heater output (6,3v/30 = 210mA) / 28KΩ load on plate output (100v/28K = 3,57mA)

Waiting for the second body-donor to build the updated version (another Tr out / 1uF tin-foil coupling cap. / another capsule)
To be continued...

 

[rock soderstrom]

PSU-2 buit and tested = 100% OK

Hi Emmathom, is this the schematic of your PSU?

 

[Emmathom]

Hi Rock
Plate voltage has been leveled up to reach 100v (96v ~100v) according to Thor's view.
Here is the last schematic with a 8VA transformer. This little Tr from Ali is ok and save space (compared to the 10VA in the other PSU)
I put 1,2KΩ R serie to get enough voltage (105v) and a 33KΩ load to be sure the 1w zener string will see at least 5mA to activate. So the total load is close to 6,25mA
The 56uF@450v (and not 250v as mentionned on the schematic) is because I didn't have no more @100v capacitors in stock and are supposed to filter some noise from the zeners

 

[thor.zmt]

The 56uF@450v (and not 250v as mentionned on the schematic) is because I didn't have no more @100v capacitors in stock and are supposed to filter some noise from the zeners

You already have 470uF there, move the 56uF to after the 470R. This creates a further lowpass at 6Hz, will kill zener diode noise much more (where it is now it is doing zip).

Or leave the 56uF in place and move the 470uF to after the 470R which will be even better, forming a 0.72Hz lowpass so at (say) 120Hz noise will be attenuated 41dB and noise reduction goes up from here.

Thor

 

[Emmathom]

Roger !

 

[rock soderstrom]

Thank you guys!

 

[Emmathom]

Thank you guys!

I think you could put "what you get" in place of the 56uF > until it's 100uF or more @ 250v is well enough (but the straight lowest volatge - 100v - is a bit low at my taste)

 

[Emmathom]

@rock soderstrom
Let us know how your 6AK5 project progress

 

[Emmathom]

@rock soderstrom
Let us know how your 6AK5 project progress

I was hoping for more than a thumb - pouce - like

 

[rock soderstrom]

I was hoping for more than a thumb - pouce - like

Me too, I'm still waiting for parts!

 

[Emmathom]

Me too, I'm still waiting for parts!