G9 with Beyer Input and Edcor Output transformer picsssssss

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bernbrue

Well-known member
Joined
Mar 13, 2006
Messages
1,516
Location
Wolfenbüttel - Germany
Hi,
oh la la, what a nice sounding mic preamp. I used Beyer input (ratio 1:5) and Edcor XS1100 as output transformer. I did the trace cut and wired the DI jacks directly to the pcb. First I placed the Edcors to the right but since they are only shielded by a thin copper foil they caught a lot of hum from the power transformers. Shielding with a piece of mu metal didn´t help at all. So I decided to place them to the left as far as possible. Voila, no hum at all. The sound is absolutely fantastic. With the DI I tried keyboards (hammond organ B3), I tell you, really fat. Enjoy the pics. Thanks a lot Jacob for this splendid mic preamp. Big thanks to Kubi who encouraged me to try the Beyers.
regards
Bernd

G9_001%7E4.jpg

G9_ready_002.jpg

G9_ready_005.jpg

G9_ready_007.jpg

G9_ready_009.jpg
 
WOW Bernd! Nice Job, did you have different iron in before or this was it!? Dare i ask how does it sound!!! :green: the bottom pic is going to make some people jealous! :wink:
 
Woww!!!!
Nice job!!!Nice pics too!!!
Effectivement , la dernière va faire des jaloux.....Dont moi !!!!

:thumb: :thumb: :thumb: :thumb:
 
Hi,
the pile of unfinished projects is much higher than the pile of finshed projects shown in the last picture :wink: . Well, the G9 was built with parts I had laying around in various boxes, so there was no choice between different input/output transformers. Despite a pleasant boost at 15Khz frequency response is absolutely flat just down to 50 Hz .
G9_Line_Spectrum.png


I´ve got OEP transformers in my pultecs, they are really great. The overall sound of the G9 is amazing and quite variable (gain control). Choice of tubes and transformers are quite important for the sound.
regards
Bernd
 
That's very flat - I found a similar response with my Beyer 1:7s. You appear to only be 1dB down at 20Hz. The lift at 15KHz is typical of the Beyers and can be tamed by a Zoebel network if you like.
 
Question for Beyer transformers users....since their core ar so small will they lack headroom or are they just fine?

Thinking to complete my New York Dave 1 tube preamp with Beyers!

GReat Build....and nice panel....
 
Great tips for layouts and grounding on those images, bernbrue! Thanks. (could say the same about your poorman)

[quote author="3nity"]Question for Beyer transformers users....since their core ar so small will they lack headroom or are they just fine?

Thinking to complete my New York Dave 1 tube preamp with Beyers[/quote]

Headroom is just fine for input, but turns ratio is probably too low, at least on this particular one bernbrue used. Remember you'll end up with not so much gain (somewhere at +40db or so).

I wanted more so I ended up with 1:8 Jensens and two-bottle mod (and even that's on the lower side of recommended ratios), but now it's a workhorse and even handles ribbons, like a decent tube pre should.

One-bottle really needs something like 1:10 or more, unless you want more like a line amp or something less gainy for hot condensers..

I got one of those G9 brewing as well. will be interesting to hear a different topology to the NYD pre-amps.

And will be a refreshing change to all my point-to-point knitting.
 
Actually i tried the 1 bottle with OEP i think 1:5 ratio and i had enough gain....the beyers i have are 1:7 ratio...
 
[quote author="3nity"]Question for Beyer transformers users....since their core ar so small will they lack headroom or are they just fine?
...[/quote]

that´s exactly what I thought as well, but Jens and Kubi told me, that the Beyers have a nickel core instead of a ferrite core. Nickel cores don´t saturate as fast as ferrite cores do. That´s also the reason why they can be kept much smaller than standard transformers. Indeed these tiny little transformers have quite a lot of headroom and sound really amazing.
regards
Bernd
 
"Nickel cores don´t saturate as fast as ferrite cores do. That´s also the reason why they can be kept much smaller than standard transformers. "


OK.

Size depends on the application.

A mic input signal is very fragile, so you want to use a transformer that is also fragile.
Nickel sucks in lines of flux quicker than a Hoover vacuum cleaner, so we can get out transformer working good with just a few turns compared to steel lams.
So no copper loss.

Also, Nickel is very efficient.
Very low core loss.

Which transformers use a ferrite core?
I know of some inductors, but never seen an input made from ferrite.
 
Hi ,
thanks for the explanation, CJ, couldn´t have said that better (sometimes the language barrier is hard to overcome, especially concerning technical terms) Yes, Jens, I meant steel.
regards
Bernd
 
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