G7 - What bodies to use (& what not to use...)

Hi all

I'm about to build a G7, & I'd like to use a cheap mike for the body & capsule.

Will this work with a Marshall MXL 2001? Will there be enough space?

Any other suggestions?

Regards
Peter

Peter

A 2001 will fit a royer circuit you might be able to fit a ef86 with a jensen transformer like the royer circuit but it would be tight. Maybe a studio projects C1(cardiod only) or C3 conversion to tube they have better capsules than the MXL 2001. The mxl2003 might fit the g7 circuit (not the PCB) The 2003 has a good 797 capsule and a nice grill.

If you are going to build a tube microphone and do all that work The extra money for a good capsule is worth it IMO.

hello


i had a mxl v67g... and i thougt it would be possible to use it for my g7 (which isnt ready yet)... it wasnt!!

the mxl v67 is too tiny for the g7...

Hi Gus

Thanks for the info.

I'm battling to see the actual measurements of the G7 PCB & assembly, I assume I'm being really stoopid

The MXL 2003 has a 55mm x 195mm body. Is this too small a diameter for the PCB? Or is the length a problem?

Regards
Peter

Converting a low cost LDC mic to a G7 is a nice idea (been thinking about it myself, actually).

I'd probably plan to make some tweaks to the layout and do my own PCB, or build it on perf-board just to make sure I could squeeze everything inside the shell.

But, in the USA, where can you get a 7-pin replacement connector for it?

~ Charlie

Peter

I don't think the g7 pcb will fit any of the microphones. I was thinking you might build it on perf or design a pcb for the 2003. Look in the meta at the picture of 3 microphone two are 2001 and one is a Sam Ash Ld1 the LD1 has a 6072a and a jenson 12:1 transformer (the one listed in the royer mod) mounted inside very tight fit! Point to point wired It is close to a ela m251 circuit cardiod only.

If it is going to be one pattern microphone based on a mxl2001 v67 etc the Royer circuit might be the way to go with a regulated heater supply at 5.7Vdc

so there's absoultely no feasible way to make the G7 out of a MXL V67G? I really like the v67g and grill that's why I want to use it .

there is a way... but a lot of work too...

actually i want to use my v67g for my g7 project.
i only remove the middle part of the mxl, a friend of mine will make a new, longer, metal body... so i can use the grill and the bottom part.

When the topic is up... would it be ok to house it in an aluminium case?

Robert

Of course this discussion is overlooking the fact that you could always mount the tube out the side as Duka and Sony have done. This means there's room to mod any mic to a tube mic. The only metal work required would be a cover for the tube and you'd have to remove the tube before opening the mic.

Robert,

Yes. But it has to be fully shielded all way around.

Jakob E.

Hey guys,
I just had a few questions for the G7 builders and specially the G7 master Jakob... and please pardon my ignorance if questions are dumb..

1- on the Gyraf website I noticed that the power transformers for 220 are for 9v and 15v and for 110 they are 9V and 7.5V.. any special reason why that is??

2- Does anybody in the US has a part number for some of these 110 transformers.. I"m not too sure about the ones I found on the neward site. Part #95B8917 and #95B8919

3- I'm mounting the tube inside the mic, unlike duka.. So I was thing about making some vent holes on the body of the mic so the heat would get out. Is that a good idea?. Or should I not worry about the tube heating too much?...

4- I was also thinking about a 7way switch for the pattern select.. I was wondering what the values would be... is there an formula that I can use??
Position 1 for omni, 4 for cardioid and 7 for bipolar, and the others inbetween...

Thanks guys,
Gil

Gil,

1. For 220 use we tranform down to 9V, then use the 15:220 to step back up to

(220 / 15) x 9 = 132V AC

You get the same if you use 110:7.5

(110 / 7.5) x 9 = 132V AC.

3. Don't worry about the heat.

4. Just divide the total resistance into 6 equal parts.

Hope that helps.
Stewart

[quote author="BR"]1- on the Gyraf website I noticed that the power transformers for 220 are for 9v and 15v and for 110 they are 9V and 7.5V.. any special reason why that is??[/quote]
It's an error - why don't you fix it Jakob?

What you need is a 120 to 9V transformer and a 230 to 15V transformer. The second transformer should be the same for both 230 and 120V operation.

If you do use a 120 to 7.5V transformer you may overload it, and it may "self destruct" - depending on the quality. If you use a 230 to 15V transformer you will have no problems (just look for a 115 to 15V with dual primaries).

Best regards,

Mikkel C. Simonsen

Updated the page...

:razz:

Jakob E.

Come on new people look in the meta's!!!! there is alot of ideas there pictures of peoples microphone builds. This is not sounding like DIY to me but follow the leader! I don't think there has been so much easy to get info on microphones in one place as this. The questions people ask means they don't read the metas! The information shared here is great READ THE METAs!

thanks for the update Jakob..

4. Just divide the total resistance into 6 equal parts

Click to expand...

So from the schem it looks like the total is 210K, so 6 35k or close resistors would do fine???

Does anybody have part numbers for these transformers in the US? I"m kind of having a hard time finding these things...
thanks
Gil

[quote author="Gus"]READ THE METAs![/quote]

It's a good point. A lot of hours have gone into compiling those metas and there is a wealth of information there.

:thumb:

Hey guys,
I really don't know which of my questions triggered the reaction above, but I'm sorry for the redunt questions anyways... I just looked over all the threads in the Mic meta and I can see how this can get really boring after a while, nevertheless, some of my questions weren't answered in the threads in the meta... like the Transformer question and the 7 polar pattern questions....

sorry again....

Gil

Gil,

Not necessarily your questions in particular.

Polar pattern is set by 2 x 100K on the G7, so 6 of 33K would be fine.