Telefunken EF 86 valves LC10 or LC24

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Interesting,  my very first G7 I used a Lundahl transformer that I had on hand that was 7:1 and we liked it. One day a year later I decided to try the Lundahl 5:1 output. My wife wanted the 7:1 back, which she got,  but I liked the 5:1 for it's stronger (thicker) mid range which made the mic seem less present in the highs.  I think she liked the free feeling , less loaded down response of the mic.  I think it would have sounded better to me ( 7:1) with a larger head basket like a U47 or U67.
 
That's why am running capsule with 50V.
If you will go up with the ratio of transformer, high frequency is less damped becuase of better impedance matching.
Try cathode capacitor at least 220uF + plate voltage filtering cap 2.2uF + 0.5uF output cap.
I tried  (a/b test + preamp measurement response) 3.3uF, 2.2uF, 2uF, 1uF, 0.5uF.
Tried different caps Roederstein MKP, MKT, MKC and ITT/Siemens MP.
Worst was 3.3uF MKP.  The best was 0.5uF MP.
Like if you took off the blanket from microphone :)
Response to at least 20Hz is the same for all values!
 
OK!  I'll play with this on my next G7 build.  I would like to get to the smaller output cap.

I have some mini 1:10 beyerdynamic transformers, do you think they are a waste of time?

Do you like the E80F over the EF86  because it's more quiet or what?
 
In this one am using exactly beyer 1:10  :)
I used them in several microphones, LDC tube and FET and FET SDC.
Great transformers!
I had problem with one of these 1:10  - very weak low end response.
I just demagnetised it and work as it should be.
For output cap try to find MP.
Why E80F?
It's clean as hell, comparing even to the EF806 it's much more quiet.
Since it suck more current, circuit behaves differently so it's hard to make true A/B comparison.
First impression is that the tonal balance is much more better also :)

My circuit is optimized for that tube and transformer.
If you want, you can use complete schematic, but probably you will need to increase value of R9 in PSU or use lower AC transformer.
Am using selenium rectifier so there is higher voltage drop on it.
With silicon rectifier you can get  up to 10V higher voltage.

For capsule polarisation voltage you will need to tweak R3 and R10.
All depends on which capsule it be and what headbasket.
My headbasket boost frequency range from 3kHz, where the capsule have a bump, that's why i choosed 50V polarisation voltage. If it will be more flat i will go higher with the voltage.

Also value of cathode resistor is crucial!
 
Interesting posts, In76d.
Keep 'em  comin'.  :)

Hitchhiker, E80F is a great tube for sure.
Some say the (technically less perfect) EF86 has more character and low mid meat.
But like In76d said, it will depend on the configuration, too.

Since you're in Vancouver, check out the preamp in the link below. Not saying you should buy it.
It takes advantage of the EF86 goodness, as a pentode and as a triode.
http://sonicfarm.com/pro-audio/creamercreamer-plus-pentode-preamp/
 
hitchhiker said:
Can't wait to get some E80F tubes.

I use Thiersch M7 mostly.  What capsule did you use in this build?

I started with AKG teflon CK12 and finished with chinese K47.
Here you have short form of parameters.
 

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micaddict said:
Interesting posts, In76d.
Keep 'em  comin'.  :)

Hitchhiker, E80F is a great tube for sure.
Some say the (technically less perfect) EF86 has more character and low mid meat.
But like In76d said, it will depend on the configuration, too.

Thanks ;)

Yes, configuration is most important.
You need to change at least cathode resistor.
If you will use EF86 in my circuit it would sound even worse as in original circuit :)

Here's cardioid frequency response. Not smoothed, if you will smooth it with 2dB averaging it would be flat in most of range like in commercial response charts.
This is just a demonstratively.
sh*tty equipment, sh*tty chamber (20dB background noise and elevator :) ). It is close to true from 80Hz.
From 2kHz a bump is also boosted by burst of sound from a resonance and sound reflection in the chamber... The real bump is at least 2dB lower.
 

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I don't know, i never used it. Looks like japan made?!?
Probably yes :)

Last one which i bought were these:
http://www.ebay.pl/itm/20x-0-5uF-160V-AXIAL-10-5x34-10-METALLIZED-PAPER-A-1183-/182050432938?

I used it in two microphones and they sound good. Also size is good, these aren't so big.
Seller should relisted it, if not out of stock.
 
ln76d said:
With the pinout - YES.
It's little bit longer than EF86.
E80F suck more current.
This affect polarisation voltage which even with EF86 isn't equal for omni.
Anyway it should be better for 5:1 output transformer and for polarisation voltage it's only change in one resistor in original circuit.
Here's my version with E80F and 10:1 output transformer.

Excellent stuff,sounds cool.....Unfortunately its all way over my head .I'm trying to buy the parts for kit mic...I'm just a humble guitarist/studio head ,who trying get good mic for making some music with. Thanx for the tips....Hoping to find a mic builder locally(Brighton Sussex), who can build it for me.I will pass on this info to them.
Thank you all
 
ln76d said:
With the pinout - YES.
It's little bit longer than EF86.
E80F suck more current.
This affect polarisation voltage which even with EF86 isn't equal for omni.
Anyway it should be better for 5:1 output transformer and for polarisation voltage it's only change in one resistor in original circuit.
Here's my version with E80F and 10:1 output transformer.


Here's a recent remark by Dave Thomas of Advanced Audio microphones:

I have built or serviced a few EF86 circuits and was never happy with the results. Neumann did use it in the U67 but there is 15db of negative feedback even with the fixed bias to reduce the plate load impedance

Care to comment?
 
Since this thread is hijacked already, I'll add one more question

@Ln76d - Could Beyerdinamic's TR/BV  310 007 001 be used in your configuration?
It's 1:7 transformer 10k:200R

I'd rather use that than to buy lundahl that gyraf spec'd for G7. Simply because I already have it! :)
 
For G7 with EF86 you can use it without any problem.
For E80F should be also good but you can try to change a little plate resistor and cathode resistor to get proper response.
With EF86 you should get output impedance around 300ohm so for the preamp it's a little bit better.
Definately for beyer use lower value output cap - 0.5uF is enough. If you will fell that there's drop in low end response, increase cathode capacitor to 220uF.

Here's a new project which is really similar to the G7 but it will be little bit different sounding.
Not because there's smething wrong with Jakob G7 - it's a briliant circuit - but because i want to make more suitable for chinese k47 :)
http://groupdiy.com/index.php?topic=62441.0
I'll update it soon.
 
Thanks ln76d for your response!

You should definitely open a new thread so we can all discuss your mod for G7.

I'm keeping an eye also on your S216 thread! Nice work! Very interested to try that also!

Let's not hijack this thread now completely.
I'll have more questions later when I get to the building it.
I still need to order caps and wait for the capsule so I'm not yet ready to assemble it.

:)

Luka
 
ln76d said:
For G7 with EF86 you can use it without any problem.
For E80F should be also good but you can try to change a little plate resistor and cathode resistor to get proper response.
With EF86 you should get output impedance around 300ohm so for the preamp it's a little bit better.
Definately for beyer use lower value output cap - 0.5uF is enough. If you will fell that there's drop in low end response, increase cathode capacitor to 220uF.

Here's a new project which is really similar to the G7 but it will be little bit different sounding.
Not because there's smething wrong with Jakob G7 - it's a briliant circuit - but because i want to make more suitable for chinese k47 :)
http://groupdiy.com/index.php?topic=62441.0
I'll update it soon.
After all my Valve questions,I changed the build...its now gonna be a 251, PTP ,CT12,Samar ....so its a 6072 valve !!
Its in the build  spec, and also recommended to me by TC.

But Hey...It got us all talking, and got the juices flowing....All good... and plenty of great input from everyone....sure I'll be back here reading this post on future builds  Lol        Its all helped me work out ,what the hell it was, that I wanted to build.
Nelly
 
micaddict said:
Yes, In76d, do keep it coming, please!
Whatever, whenever and wherever.  :)

shot said:
Thanks ln76d for your response!

You should definitely open a new thread so we can all discuss your mod for G7.

I'm keeping an eye also on your S216 thread! Nice work! Very interested to try that also!

Let's not hijack this thread now completely.
I'll have more questions later when I get to the building it.
I still need to order caps and wait for the capsule so I'm not yet ready to assemble it.

:)

Luka

Thanks Guys!

We can talk in the S216 topic about G7, tubes and everything else :)
Luka - if i will make satisfied input section for S216 - i will giva a "shot" and try 7:1 transformer :)
 
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