transformer mounting in a DI box enclosure

kevinnyc

Active member
Joined
May 4, 2006
Messages
32
Location
New York City
I'm building a DI box right now and I was just wondering if anyone has any suggestions for a good way to fasten the transformer to the box so it is secure and doesn't move around. I am using a Jensen DB-E transformer and I'm just p2p wiring the whole thing because it's a simple passive DI.
 

kevinnyc

Active member
Joined
May 4, 2006
Messages
32
Location
New York City
the transformer is used, but I do have a mounting bracket for it. I was told by someone that the unit would hum if the mu metal can touched the chassis. I was confused because the mounting bracket is metal and would obviously be connecting the outside of the transformer to the metal chassis of the DI box. Is this wrong, or did misunderstand what he was saying? Thanks for your quick reply.
 

pucho812

Well-known member
Joined
Oct 4, 2004
Messages
12,194
Location
third stone from the sun
[quote author="kevinnyc"]the transformer is used, but I do have a mounting bracket for it. I was told by someone that the unit would hum if the mu metal can touched the chassis. I was confused because the mounting bracket is metal and would obviously be connecting the outside of the transformer to the metal chassis of the DI box. Is this wrong, or did misunderstand what he was saying? Thanks for your quick reply.[/quote]

well I have a passive DI with a jensen which I DIYed/ IN fact it has nothing in it other then connectors and a trafo. It's happens to be one of the best sounding DI's I have. No hum yet and even if what can I do but switch it out as it has no ground lift switch. Yes I could put one in but why bother.
 

kevinnyc

Active member
Joined
May 4, 2006
Messages
32
Location
New York City
ok, thank you for the help. I have a bunch of those tyRaps, so that should be easy to fasten it that way.
By the way, I did a little searching on this site but I can't seem to find how Mu Metal actually works in transformer shielding. Is it supposed to touch the transformer coils, or be completely isolated from it?
 

mikka

Well-known member
Joined
Mar 2, 2005
Messages
336
Location
Australia
The transformer coils will have an earth wire soldered to them, as will the shield. The mu shield will reduce the electrostatics that hit the coil....... and cause any magnetic field to follow the shield and flow around transformer inside, instead of through it.

Sumfin' like that....

I've got an old Triad tranny which was probably chassis mounted..... it has a bit of aluminum angle for a bracket..... no magnetic issues....
 

CJ

Well-known member
Joined
Jun 3, 2004
Messages
14,147
Location
California
I think that is a small xfmr.

But if not, and it's PC mount, bolt it down good if it travels.

We shipped a brand new product out with no xfmr bolts.
Just a 625 EI jobby, with 8 pins holding it to the board.
All 5 units came back with the transformers a rattlin around.

Ripped the pins right out of the board.
Dang UPS!
 

drpat

Well-known member
Joined
Mar 30, 2005
Messages
1,081
Location
NorCal
Kevin,

I built a quad DI out of four of those transformers with the supplied bracket, and I've never had the problems that you are describing. They sound really good too...
 

tony dB

Well-known member
Joined
Jun 4, 2004
Messages
1,304
Location
Belgium
I've glued trannies in little boxes many times. Those silicone kit used to hold glass into windows for example, works great. It is a little messy if you have to take it back out, but with a sharpie (spelling? razorblade knife?) its easy to remove and clean. Never had to remove them that much btw...
I don't like the mechanical part of diy that much :twisted: especially since my metal/wood workshop is now a part of our studios :thumb:
 

tony dB

Well-known member
Joined
Jun 4, 2004
Messages
1,304
Location
Belgium
sharpie as in cutter knife... :?:
didn't realise the same words are used for a pen :oops:
I meant one of those things people use to cut out stickers, or parts of a pcb-trace... (made a note about this in the previous post)
 

pucho812

Well-known member
Joined
Oct 4, 2004
Messages
12,194
Location
third stone from the sun
It was my first ever DIY. Used a "JT-DB-E" Jensen.


Followed the aplication schemo and made it point to point except left out everything. So all thats inside is the trafo which is mounted via the lil L bracket it came with. Then wired it all up. By far one of the best passive trafos I used. next to that westlake which uses the same trafo. Only difference is the westlake got the ground switch and has that filter which can go to either to output to the amp or the output of the DI. I've yet to get a photo of that thing. Lost my digi camera at aes. Yet to replace it.

http://www.jensentransformers.com/as/as007.pdf
 

guy_4

Well-known member
Joined
Dec 23, 2004
Messages
273
Location
Near Paris, France
Hello,

I built several DI boxes with the JT-DB-E Jensen transformer.
I use a piece of " hard foam", ( I think it's called Styrofoam) this is the thing you get in package for protection of equipment.
I cut it to the internal size of the box - less connectors and switches -, and I cut a hole in this piece of foam where I fit the transformer in it.
I leave all the lenght on the wires of the transformer and do the soldering.

Et voilà !
Easy, no dril, no glue, no screw. cost nothing.
Never had any problem, no hum, no broken leads or transformers.

Guy
 
Top