Aurycle FET Mikes

[Matador]

Using the PNP follower (or any follower topology for that matter) lowers the output impedance of the front end driving the transformer.  This improves the transient response of the RLC combination (output impedance * transformer L * coupling cap).  The lower R may lower the noise floor a bit too.

However in my experience it's a subtle change, and with a good transformer it's pretty much a wash in either case.  I suspect the entire reason for the follower in the clones is so that the manufacturers can get away with a lower ratio (e.g. much cheaper) transformer:  sonic considerations probably didn't enter the equation.

 

[berkleystudios]

any one know anything about the stock transformer? which colors correlated to 1, 2, 3, 4? using it in the u87 build till my cm 2480 comes in. 

 

[Blue Jinn]

any one know anything about the stock transformer? which colors correlated to 1, 2, 3, 4? using it in the u87 build till my cm 2480 comes in.

The stock transformer looks like the 11.5:1 I picked up for use in Royer Mods. The stock MXL 2001 transformer looks different and is 2:1 and this is the exact same circuit (even the nomenclature on the PCB's is the same.) I am pretty sure the color coding of the wires is the same, I'll take a look tonight and report back. Has anyone measure the transofremer ratio on the Aurycle?

EDIT: The trafos I have are Pri: Red(+)/White Sec: Green(+)/Black. The 2001 schematic and transformer has the same scheme. The circuit is the same as in the MXL 2001. However, the transformer I pulled out is 2:1 and red not yellow. I have another 2001 I can look at to see. The 11.5:1's I have don't fit in the stock housing though, without some minor machine work. Hope this helps. 

 

[JoanRovira]

Hello!

I have read the thread, and now I'm trying to modify a microphone to match the U87ai.
I have a T.BONE SC600 and to take advantage of Multi-pattern, will try to recreate the U87ai.
It's for my research project final college.
I found the schematics, but there are some components which are not:
- One is the DR1-90 462, not that type of component is.
- The D7-62V is a diode but not if it is a zener
- T1-8280800006 has to be a transistor, but have not found any referral is that model.
I attached a link to the diagrams I found.

http://depositfiles.com/files/4igq70wpv

Sorry for my English
Thanks and I hope your answer.

Greetings!

Joan

 

[tskguy]

Joan,

You may have a better time actually building the older u87 there are some issues building the newer version. Mainly the DC to DC converter section. Please check out this thread http://www.groupdiy.com/index.php?topic=48030.0
It discusses mainly the vintage 87 but poctop kicks around the idea of doing the AI version and you can read about some of the issues.
Good luck!!
E

 

[duduac]

Hi Guys,

I know this is an old topic, but I`m giving a go anyway

Just finished soldering my Aurycle using the pcb that came with it until I receive the new ones for the U87 project.

When plugged my mic in a very interesting thing happened, I`ve got no output if I`m speaking on the mic, but if I touch/scratch/knock it I`ve got a clear sound....

Can anyone give some light here? I`m not sure what went wrong and how I can fix it.... I`ve got a multimeter and a signal generator if that helps

Cheers