Rossi

Re: ELAM 250/251 vs G7 with CK12
« Reply #20 on: July 07, 2009, 10:22:34 AM »
Don't get me wrong, I do like Pikatron stuff. What's the ration for the 713M and in what modules was it used? I couldn't find any data on that one. Bürklin has some Pikatron mic transformers that I'd like to try (ÜP 3095 M, 1:10). Those are relatively small, though. I have some RÜP 817M transformers that I haven't tried yet. They're fairly heavy and maybe a little too big for many mic bodies, though.
"I am not a number, I'm a free man!"
"Hahahahaaaaaa!!!!!"


Lowfreq

Re: ELAM 250/251 vs G7 with CK12
« Reply #21 on: July 09, 2009, 12:15:30 AM »
Ok, I ripped out the G7 circuit and tried the ELAM. Wow!! big difference on the top end :o

I quickly recorded myself with the G7 before ripping out it's guts. Then recorded the same thing with the ELAM & the same chain.
Chain was Mic--->Baby Animal Pre----->Analag opto vlave compressor---->Mytek Converter

Not the most scientific test, but I tried to keep levels, distances, compression etc as close as possible.
There's no EQ on any of the mics, just some compression, and a little bit of delay....................

The song is by "The Script", and the music is just one of those $1.99 karaoke tracks, so I hold no claim to how that sounds....bad or good.......
And, excuse the singing....... It was all done in a rush to see how the mics sounded............

Here's how the G7 sounded
http://twin-x.com/groupdiy/albums/userpics/Script_G7.mp3

And here's the ELAM circuit
http://twin-x.com/groupdiy/albums/userpics/Script_ELAM250.mp3

And as a comparison here's my Royer mod with a Dale M7, and a cinemag CM-2461. Wrong ratio & impedance, but it seems to work.
http://twin-x.com/groupdiy/albums/userpics/Script_Royer_K2.mp3

Quote
you will have less bass with an elam circuit and you will have more noise !
It's definitley got more noise/hiss than the G7, but it's not unusable. Works well for vocals. I wouldn't be trying to record quiet sources with it at the moment though.
I've got a couple of GE6072 five star thingys, and I've got the quieter one in there. Mind you 2 valves is not the best selection to sort through and find a quiet one. ::)

I've had a bit of a search about 6072 vs 6072a, and these are a couple of the things I've found............
Quote
6072A is computer rated and has higher leakage resistance than 6072
Quote
The 'A' in 6072A is supposed to indicate "low-nopise" but the GL 5 Stars are usually extremely quiet
Would the 6072A generally be quieter than a 6072?? Or again is it one of those things you'll only find out by popping one in.

Also, the MK7 psu has been suggested......and I've been educating myself on "ripple"
Would that bring the overall hiss down?? or is it more to do with the noise level of the tube itself.
The MK7 seems to have a lot more filtering on the heater side of things.

bobschwenkler

Re: ELAM 250/251 vs G7 with CK12 (With Soundfiles)
« Reply #22 on: July 09, 2009, 01:59:30 AM »
Interesting comparison. I think the ELAM circuit works a lot better for the song, though I can tell it has more high end than I'd prefer in personal use. The G7 has a nice top end to my ear but sounds just way too muddy down in the lower frequencies. I wonder if I'm hearing any result of that bump in the low end on the plots.
Complete 312 to M1 type preamps, and anything in between - hundreds sold - The Hybrid 312: www.schwenkleraudio.com/312

www.dubnarcotic.com
www.schwenkleraudio.com

e.oelberg

Re: ELAM 250/251 vs G7 with CK12
« Reply #23 on: July 09, 2009, 08:02:29 AM »
Don't get me wrong, I do like Pikatron stuff. What's the ration for the 713M and in what modules was it used? I couldn't find any data on that one. Bürklin has some Pikatron mic transformers that I'd like to try (ÜP 3095 M, 1:10). Those are relatively small, though. I have some RÜP 817M transformers that I haven't tried yet. They're fairly heavy and maybe a little too big for many mic bodies, though.
the ratio is written in db 0 : 19 db, so it should be 1:9.5, I found them in a ORF Sitral Desk Module, I guess they were produced in the 70ties, They are a 30x30x30mm cube . I prefer the midrange of the Haufe T14. BTW I do have a TAB Funken werk t14 too, it sounds good, maybe a bit better than the Haufe,

Rossi, could you do me a favour and look at this schematics ?
http://www.groupdiy.com/index.php?topic=34209.0

nicholas

rodabod

Re: ELAM 250/251 vs G7 with CK12
« Reply #24 on: July 09, 2009, 08:10:25 AM »
Ok, I ripped out the G7 circuit and tried the ELAM. Wow!! big difference on the top end :o

Which value of grid resistor are you using here? You might be hearing a different frequency balance with the lows being rolled off slightly.

Rossi, could you do me a favour and look at this schematics ?
http://www.groupdiy.com/index.php?topic=34209.0

I can't see your schematics Nicholas, but again, looking at your post, I wonder if you used the lower value grid resistor and might have been hearing relatively more treble.
Quote from: tv
punchy fat bastard chip

e.oelberg

Re: ELAM 250/251 vs G7 with CK12
« Reply #25 on: July 09, 2009, 08:37:25 AM »
Rod,
I use 150M from grid to ground, I measured the amp and there is no bass roll off. I don't know why you can"t see the schematics. I'd like to get rid of the relais in the mic, for changing the polar patterns... maybe you can download the file ?


nicholas

Gus

Re: ELAM 250/251 vs G7 with CK12 (With Soundfiles)
« Reply #26 on: July 09, 2009, 09:20:03 AM »
Lowfreq

Compare the specs of a 12ay7 to a 6072

http://www.mif.pg.gda.pl/homepages/frank/sheets/135/1/12AY7.pdf

http://www.mif.pg.gda.pl/homepages/frank/sheets/093/6/6072.pdf

I have used 12ay7s and some were very good.

IIRC there was a good thread at PSW about the 6072
« Last Edit: July 09, 2009, 12:06:10 PM by Gus »

e.oelberg

Re: ELAM 250/251 vs G7 with CK12 (With Soundfiles)
« Reply #27 on: July 09, 2009, 10:06:29 AM »
Gus

are you refering to the schematics I draw ?
nicholas

Rossi

Re: ELAM 250/251 vs G7 with CK12 (With Soundfiles)
« Reply #28 on: July 09, 2009, 10:43:21 AM »
nicolas, the reason we can't see your schematics is because you put a PDF-File reference between IMG tags. Convert them to jpg or gif, and everyone can see them. I only found the url when I hit the quote button.

I'll have a look at the schematics later, but I'm sure Gus and others know more about tube circuits than I.
"I am not a number, I'm a free man!"
"Hahahahaaaaaa!!!!!"

Rossi

Re: ELAM 250/251 vs G7 with CK12 (With Soundfiles)
« Reply #29 on: July 09, 2009, 10:55:22 AM »
Err, maybe I'm crosseyed, but looks like you have 1.8k + 47u  between heater and ground. Shouldn't that go between cathode and ground?
"I am not a number, I'm a free man!"
"Hahahahaaaaaa!!!!!"


burdij

Re: ELAM 250/251 vs G7 with CK12 (With Soundfiles)
« Reply #30 on: July 09, 2009, 11:16:24 AM »
In your samples the 6072 may sound "brighter" with a bit more low amplitude detail because its gain is about double the gain of the triode connected ef86. But I also think its giving some higher level distortion on plosives. You could verify that by looking for clipping with a scope at the preamp output. Between the two capsules, I prefer Dale's capsule. It has a fuller low mid which is good for your voice as its in a higher register. I think the dullness of the Royer combination comes from the 5840 which is some distance down on my list of preferred tubes for microphone use. I am not a big fan of self-biasing frame grid tubes either (no grid resistor). Without a fixed bias point, at the current at which tubes operate in microphones, drift in the bias point due to low frequency modulation will be significant. I think you would like the M7 and 2461 transformer with a 5703 (gain of around 24, as I recall) or the triode connected ef86 which is a good match to the 2461. Loading of the microphone output is going to affect your overall performance too. These transformers have a great deal of inductance and significant leakage capacitance due the huge number of windings.

In the discussion in this thread about peaks in the low frequency range, I think too much emphasis was placed on resonance in the audio band. If you calculate the resonance frequency considering the inductance and the size of the coupling capacitor, you would find that the resonance frequency is going to be below 15 Hz. This is well below the frequency of the lowest stop on a pipe organ.

All in all, the differences between all configurations is subtle and all are at least comparable to the better commercial tube condenser clones out there.

Lowfreq

Re: ELAM 250/251 vs G7 with CK12 (With Soundfiles)
« Reply #31 on: July 09, 2009, 07:12:19 PM »
Quote from: rodabod
Which value of grid resistor are you using here? You might be hearing a different frequency balance with the lows being rolled off slightly.
I can hear the roll off of the low freqencies with the ELAM. Maybe a fraction too much for my my voice. With my wife's voice it works great. But the top end is how I would end up EQing things. Maybe I listen to too much bright, modern music but I seem to favour the idea of using less EQ but having a brighter mic. (different for every voice, I know)
One thing I like on both capsules, is how my esssses sound. I wouldn't feel I have to pull out the desser plugin like on my cheaper mics.
I'm using a 33m here. I'm gonna try removing it, and see how I like it (after reading some of Gus' thoughts on it. Less Noise??), then I might add another one to get 66m.
Quote from: burdij
I am not a big fan of self-biasing frame grid tubes either (no grid resistor)
So you're saying the opposite to Gus? Again I'll try different options and see what happens.

Quote from: Gus
Compare the specs of a 12ay7 to a 6072
Thanks Gus. A lot of the specs are the same. Some tiny capactiance differences, but most of it the same. I struggle to understand the graphs though.

Quote from: burdij
I think you would like the M7 and 2461 transformer with a 5703 (gain of around 24, as I recall) or the triode connected ef86 which is a good match to the 2461
I don't dislike the Royer mod. It's quite smooth sounding. I might try the ef86. I've been doing a lot of reading this morning about pentodes as triodes.......
My overall knowledge about tubes is slowly increasing..............slightly better than ignorant at the moment ;)
I like that the 5703's are cheap.

The main thing for the ELAM is the noise. Any more thoughts on the PSU being the culprit??
What sort of noise does ripple bring? Just the constant hiss?? or something else??
Just for Kicks I tried it on my Royer mod PSU, and it was still noisy..........

I left the mic on for the day yesterday to see how the tube settles. It was better, less noise. Maybe I should leave it on longer??
I've cleaned the mic with circuit board cleaner, so I don't that's the issue.




Gus

Re: ELAM 250/251 vs G7 with CK12 (With Soundfiles)
« Reply #32 on: July 09, 2009, 08:28:08 PM »
I agree with burdji about possible issues without a grid to ground resistor like the royer 2001 mod does.  I use a grid to ground resistor with 5840s.   I did add a grid to ground to the 800 6au6 circuit after some time.

You need to find were the noise is coming from B+ or heater supply or the capsule

I ended up using super caps in a 6au6 build to lower the noise from the heater supply.

Disconnect the capsule make sure you have a grid to ground resistor and put the microphone body on for shielding.  How does the circuit sound for noise if it goes away it is something with the capsule part the mount, charge voltage, leakage paths, switches...

Change the tube I have had to try a number of tubes some days to find one that was low noise.  One or two is not much to try for a microphone
let the microphone tube run for days if possible to see if it gets better or worse.

I sometime build a burn in unit for tubes.  I wire up the circuit fragment plate resistor value, cathode resistor or fixed bias, grid to ground resistor and the microphone B+ voltage and let the tube cook for hours at a rated fil voltage before even trying them in a microphone

3nity

Re: ELAM 250/251 vs G7 with CK12 (With Soundfiles)
« Reply #33 on: July 09, 2009, 08:32:37 PM »
I really like the Royer MOd a lot but the Elam sounds good too.
The royer mod its like between the g7 and elam sounds!!!
Life is a path, death the destination.

Lowfreq

Re: ELAM 250/251 vs G7 with CK12 (With Soundfiles)
« Reply #34 on: July 09, 2009, 08:35:45 PM »
Cool, thanks Gus.

I tried it this morning without the 33m resistor, and it was quieter. Not a huge amount, but enough to notice through headphones.

I'll try without the capsule.

Gus

Re: ELAM 250/251 vs G7 with CK12 (With Soundfiles)
« Reply #35 on: July 10, 2009, 12:43:11 PM »
Make sure you use a grid to ground without the capsule.

 


Lowfreq

Re: ELAM 250/251 vs G7 with CK12 (With Soundfiles) New
« Reply #36 on: July 11, 2009, 08:18:47 PM »
Hey Gus,

yep, I made sure it had the grid to ground. It was still very noisy without the capsule.

Eventually I'll build a PSU like the MK7 one. Seems to be the best option. The older mics need more filtering as opposed to mics like the G7?
I'm gradually soaking up all this information.

But the next few weeks are gonna be pretty busy, and I won't get a chance to build a new PSU, so for now, I quickly perf boarded another Royer circuit, and put that in the place of the ELAM, and it's nice and quiet.
(I'm really enjoying perf boarding things. I'm not stuck to pcb sizes anymore. Makes it easy to slip in & out different circuits) ;D

The circuit sounds a little different, but not a huge amount. Same capsule, same transformer & same output cap......... And these are the main influences on the tone i guess.
It has the fullness again, now there's no bass rolloff like the ELAM.
The top end still sounds very sweet. My wife prefered the sound of the royer circuit over the ELAM, regardless of noise. I think I prefer the ELAM.

I also tried the royer with the backplate going to the grid like the ELAM, but prefered the sound with the front membrane going to the grid.
Then I read Duka said something about you recommending front membrane to grid over backplate to grid in microphones.

I also messed around with some grid to ground resistors, but only lower values like the 33m. It again made things noisy..........I might grab one of the 1gig from the G7 board and try that. With the 100uf and the 750r. But if it's not noisy at the moment I might just leave it without.

And for the mount I might try the cut up rubber ball idea, that e.oelberg had. Looks good.
http://www.groupdiy.com/index.php?topic=34185.msg418351#msg418351


« Last Edit: July 12, 2009, 04:36:36 AM by Lowfreq »


 

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