How to Build the Bruce Swedien Bass Box with vintage UTC LS10x

[Cocoman]

Hello - I´m a newbie and I just won an auction on ebay of a vintage UTC LS10x transformer and I´m planing to build the Bass Box Bruce Swedien used on the Thriller Album. Because I´m a newbie I´ve got no idea where to begin but I think it´s easy to do it as soon as I know HOW to do it

(I read it´s generally no problem to use Stancor transformer models instead of UTC but I´m not sure about it)
http://www.audioasylum.com/forums/tubediy/messages/14/145346.html

I´ll do it with the UTC LS10x. Is anyone here who knows how to do this?
I´m a newbie  (with a dream It´s only barely described here:
http://www.gearslutz.com/board/bruce-swedien/74322-thriller-michael-jackson-classic-bass-synth-p-y-t.html

another custom made version:
http://www.gearslutz.com/board/geekslutz-forum/365253-bruce-swedien-bass-di-variation.html

Pleeeeeaase help me...

The pic shows Bruce Swediens Bass Box

[Cocoman]

AND: There are different UTC transformer Types. Which one is the right one?

Bruce wrote: "What's inside that box is a Beautiful U.T.C. (United Transformer Company) Model LS 10 X Very Heavy, Super Quality, Audio Transformer.... And I use it as a direct pickup and I wire it purposely backwards.

I have tried for many years to duplicate it. HOWEVER.... Even though U.T.C. still makes that transformer...... I ordered a new transformer from U.T.C., made the Bass Box again and it sounded totaly different. I was totally bummed!!! Such is life!"

Below I posted some pics of the two different UTC LS10x transformer types that I found. I don´t know which one Bruce was talking about..
The one I´ve bought:
http://www.gearslutz.com/board/attachments/geekslutz-forum/296465d1339783230-how-build-bruce-swedien-bass-box-vintage-utc-ls10x-utc-1.jpg
Another UTC LS10x that seems to be older:
http://www.gearslutz.com/board/attachments/geekslutz-forum/296466d1339783230-how-build-bruce-swedien-bass-box-vintage-utc-ls10x-utc-2.jpg

and two pics of another custom made Bass Box with a UTC LS10 (Version without x)
http://www.gearslutz.com/board/attachments/geekslutz-forum/296467d1339783230-how-build-bruce-swedien-bass-box-vintage-utc-ls10x-utc-di-front.jpg
http://www.gearslutz.com/board/attachments/geekslutz-forum/296468d1339783230-how-build-bruce-swedien-bass-box-vintage-utc-ls10x-utc-di-front2.jpg

I hope someone in here can help me 

[pucho812]

hmmm. seems like you already asked this on gear sluts. The response  that lassoharp gave you was correct.


From what I read sounds to me like bruce built a passive DI box using a utc ls10X transformer.

If you want to build exactly what he did you will need a schematic. Since those don't seem to be readily available it will be guessing to a certain extent.

You can get a general idea of the wiring of a passive DI using a transformer from the Jensen apps page (ignore the fancy EQing and pads for now)

http://www.jensen-transformers.com/as/as066.pdf

But he has already given you the essentials:

"And I use it as a direct pickup and I wire it purposely backwards"

The easiest way to see if the $240 or $360 you may have spent is going to give you the sound you're looking for is to test wire it up (you will need either alligator clips or a soldering set up)

First, strap pins 3 & 4 together and strap pins 8 & 9 together.

1/4 guitar jack tip >>> LS 10 "50K" side, pin 7 OR 10. . LS 10 lo side pin 2 or 5 to XLR jack pin 2.

Connect 1/4 guitar jack ring to the remaining pin you didn't use for the tip, either 7 or 10. Connect the XLR pin 3 to the remaining pin you didn't use on the lo side, either 2 or 5. Plug bass in the 1/4 jack, plug XLR side into your mic pre and have a listen.


Hope this helps.

for what it's worth, the switch is probably a ground lift.

[emrr]

Wow, what a tragic waste of an LS-10X.  Build a tube preamp or compressor with it instead.

[Mr. Snoid]

I found this a while ago when snooping around:

Tod

[Cocoman]

Wow - yes it seems that I´m on the right place

Thank you for reply

@pucho812: THX yes I posted also at gearslutz and I saw the first answer there. It´s a good info to begin. For now I cannot test it because I´m still waiting to receive the transformer via USPS. My intention here was to find somebody who already has build this Box or used the transformer in this way.. But sure I´ll try to do it like this

@ emrr: Yes that sounds good - a tube preamp or compressor - perhaps I´ll try this too with a second one:)

@ Tod: THX for this nice picture - I think that clears up the things:

I plan to use it with a synth instead of a Bass/Guitar so that doesn´t matter I think.

1.) The connectors nr. 2 and 5 won´t be used right?

2.) in order to guard against misunderstandings: is this the only way to connect the pins of the transformer? --> 1+3 to XLR OUT PIN2 // 4+6 to XLR OUT PIN3 // 8 with 9 // 7 to BASS IN // 10 to XLR PIN1 and BASS IN Ground // 2 and 5 no connection

3.) which Part of the Jack Connector (BASS IN) is the Ground connection?

4.) in this custom made box there´s a switch.
http://www.gearslutz.com/board/geekslutz-forum/365253-bruce-swedien-bass-di-variation.html
why? to switch between what?

[pucho812]

your 1/4 has 2 connections tip and sleve. tip is hot, sleve is ground.


the bass di in the photo has the switch on it to have switchable impedance based on how the transformer is wired. not sure if that's on the input side or output side?

[lassoharp]

2.) in order to guard against misunderstandings: is this the only way to connect the pins of the transformer? --> 1+3 to XLR OUT PIN2 // 4+6 to XLR OUT PIN3 // 8 with 9 // 7 to BASS IN // 10 to XLR PIN1 and BASS IN Ground // 2 and 5 no connection

No.

If you read my first post then you see there is more than one way to connect the primary windings.

I only mentioned the "500ohm" connection  for convenience.  When the transformer arrives just follow the connection guide  printed on the side.  It will show you all the different ways the primary can be connected.   One question worth asking is whether the transformer in his original box used a resistive termination to fix the impedances.  It may not matter for the intended use.

[Cocoman]

Ok thank you - is there any difference between the one with printed text on its side and the one with name plate on its side. Bruce wrote he once tried to make another one but this didn't work with newer ones. The name plate looks like real vintage the printed version could be from the 80s?

Could I also use a vintage stancor HF-20x?

[pucho812]

Ok thank you - is there any difference between the one with printed text on its side and the one with name plate on its side. Bruce wrote he once tried to make another one but this didn't work with newer ones. The name plate looks like real vintage the printed version could be from the 80s?

Could I also use a vintage stancor HF-20x?

is there a difference? maybe would need to see transformer specs but I doubt there is a difference if the part numbers are the same but who knows read the data sheets. However since Bruce said it, it must be true? Maybe, maybe not.  I don't doubt  Mr. Swedien at all but, ,maybe it just didn't sound the same  and was for all purpose the same transformer.

As for the stancor again would need to read the data sheets. If you so heart set on building a  di box, there are other easier ways to go then trying to figure out which transformers will work, how do I wire, etc, etc, etc.

For what it's worth the best d.i. I ever heard was built right off the Jensen data sheet using a Jensen transformer. If you can't afford a Jensen then Cinemag will do you just fine.

[joro]

Here's a pic of the inside of Bruce's DI. Sorry it's not really clear. I can't recall the wiring. Hope it helps.

[Cocoman]

WOOOW - that gives an idea - where did you get this Foto from?

Are you able to get more information through this "source"?

[emrr]

The LS-39 is the official DI transformer, and should cost about $200 less on average.  I would bet Bruce reappropriated an LS-10x because it was what he had.  An LS-12 makes more sense as a DI than a 10 also.  The dark grey badged type would be pre 1967 I think. 

[bruno2000]

For what it's worth the best d.i. I ever heard was built right off the Jensen data sheet using a Jensen transformer. If you can't afford a Jensen then Cinemag will do you just fine.

+1 ! ! !
Best,
Bruno2000

[bockaudio]

For what it's worth the best d.i. I ever heard was built right off the Jensen data sheet using a Jensen transformer. If you can't afford a Jensen then Cinemag will do you just fine.

there is no competition between the j*nsen and the old UTC. the UTC will be better. This is an admirable project.

[lassoharp]

People will naturally ask why for such a claim as "better" considering things like what context the original was used in and why it was chosen.  Trying to find a good sound for a certain track, plug in and it happened to work well?  Or "better" = better across the board for every DI chore?  Too many factors to consider IMO.   Also the mic pre that it was plugged into and how it interacted with the transformer 'sec'.   Add to that what instrument was being used - electric bass, synth bass.  UTC LS and Jensen both spec on paper as iron meant to pass good low end at higher level without distorting.

[bernbrue]

Hi,
this thread is funny! If I only knew what Bruce had eaten when he was mixing "Thriller" I would eat the same meal everyday. Seems to make the mixes somehow better. I don´t know why, but it sounds more like .......... Chilly con Carne.

Take a Bo Hansen, G9 or REDD 47/Rude Tube with good iron  as DI and then there is no need to eat Chilly con Carne everyday.
bon appetit
Bernd

[pucho812]

For what it's worth the best d.i. I ever heard was built right off the Jensen data sheet using a Jensen transformer. If you can't afford a Jensen then Cinemag will do you just fine.

there is no competition between the j*nsen and the old UTC. the UTC will be better. This is an admirable project.

Well sir I cannot comment on using  that particular transformer as a D.I. or anything else as I never used them. More over I have never used any utc as a d.i. so I can only comment on one of my experiences which happen to be using the Jensen D.I. transformer and building the design off the data sheet.  I have used utc in other applications and to be honest it did sound pleasing to my ear but then again that's all perspective, opinion and using the right tool(in this case a transformer) for the job. Reality is this thread started because someone wants to build a d.i. In fact, he/she wishes to build an exact copy of a d.i. Bruce Swedien has built and used.  There are too much variables in the recorded sound to say this magic d.i. is responsible for every bass sound on thriller or any other album Mr. Swedien has done. More over we know from the data sheets that the UTC in question may be better suited in other applications. There is a part of smoke and mirrors to the story in the fact that he built one and then couldn't build a second one because it never worked the same? Sounds a little like P.T. barnum combined with actual fact and sonics.

Hi,
this thread is funny! If I only knew what Bruce had eaten when he was mixing "Thriller" I would eat the same meal everyday. Seems to make the mixes somehow better. I don´t know why, but it sounds more like .......... Chilly con Carne.

Take a Bo Hansen, G9 or REDD 47/Rude Tube with good iron  as DI and then there is no need to eat Chilly con Carne everyday.
bon appetit
Bernd

Well Spoken. There are many passive and active d.i. designs out there, what works for Mr. Swedien may or may not work for cocoman.

[Kingston]

I'm sorry people, nothing you say counts because you are not Bruce Swedien, no matter how sound advice and no matter how impressive technical backing you have. The gearslutz are here.

[pucho812]

You know building this d.i. will not get you any closer to making records and recording tracks in a manor that sounds as good as Bruce.