Mic splitter using Edcor WSM600/600 transformers?

[Sammas]

Hey gents! I need a mic splitter. 16 channels in, 16 direct out & 16 isolated out.

Feck it gets expensive quickly with all those transformers!

I am pondering DIY'ing one using edcors. I found this little tidbit - http://bgilbertsound.wordpress.com/2009/09/30/building-a-transformer-balanced-mic-splitter/

Before I drop a few hundred bucks on the trannies, does it look feasible?

I would have thought the 600ohm primary and secondary would be slightly too high for a microphone splitter?

 

[musika]

I found this link to 1:1 Edcor transformers and they are light as you say at only 0.04 lbs.

http://www.edcorusa.com/p/143/wsm600-600

 

[0dbfs]

They have a 150:150 in both PCB and spade-lug terminals. You could do a couple PCB's with four or eight transformers and provide options to strap it as a 1x2, 1x3 splitter or whatever...

Cheers,
jb

 

[fazer]

I had a splitter snake that used some trannys like the edcore you mentioned.  It work for shows we recorded at Red Rocks in the 80's but we recorded a show downtown at the Paramount Theater.  We had hum all over the place. 

It turned out that under the stage at the Paramount there is a sub station for power distribution to downtown denver.  It was inductively coupling to the unshielded transformers used for hum isolation.  Jensen's are expensive but would have a permalloy shield around the transformers.  Our stage box with split was steel but that was not enough for the High voltage in the substation below the stage (acutally 2 floors down). 

We looked for a rental snake splitter but could not locate anything in town that was not in use that night.  I ran to a parts store  and bought a bunch of 200 ohm resistors I believe ,  Solder them in around the transformers and removed the transformer leads from the signal path and the sound became hum free.  We had a couple hours to do sound check and recorded a successful  Gibson Jazz Fest that night that came out great. 

I would try your idea but those kind of non permalloy canned transformers can sometimes create the problems your trying to avoid.  By the way my trannys were 300:300:300  I always had the direct to stage and phantom powered any mics from my recording console , and gave the transformer isolation to house and stage monitor.  Fun Days!

 

[radardoug]

The situation where you need a splitter to really work is the same situation where a cheap splitter will not work. So you are better to do it really well, or just passive split. Jensens are expensive for a reason. They put the work in to make a transformer that does work in those real bad situations.

 

[pucho812]

If it will live at a particular venu and never leave then you may get away with less expensive transformers. But if your going to have it on a portable rig I would not cheap out ontransformers as you never know where it will end up.  Jensens are pricy but buy they will work without any humm or buzz in the most unfavorable of conditions.

 

[emrr]

Even if they were heavily shielded externally and had Faraday shields (which they don't), I'd be concerned about putting mic level into a steel core transformer meant to handle hot line levels.  I would expect operating point versus core distortion curve at operating level to be potentially, ah.....colorful.  In other words, mic levels might not excite the cores sufficiently to get best sound.  The Jensens have 30 dB shields, dual Faraday shields, and max 20Hz of +2 dBu. 

 

[mitsos]

...I'd be concerned about putting mic level into a steel core transformer meant to handle hot line levels. ..... In other words, mic levels might not excite the cores sufficiently to get best sound.  The Jensens have 30 dB shields, dual Faraday shields, and max 20Hz of +2 dBu.

That was exactly my thought when I saw this thread.  You most likely want mic-level, nickel-core trafos. 

 

[CJ]

you can use 50% Ni for this, windings are arranged differently for a splitter,

and you might want a 1:1.2 turns ratio to make up for insertion loss,

and a few shields would help, four shields if dual coil,

LS-68 would be nice, kinda big,

you could go solid state with burr brown opamps for cheaper, cleaner,

unless you want the funk, but not much mojo from a 600:600,

transformer secondaries on the UTC do not get put in series,

sec 1 of coil A gets hooked up to sec 2 of coil B,
and
sec 1 of coil B gets hooked to sec 2 of coil A.

no, this is not the Hybrid coil arrangement.

 

[sahib]

I have 1 in 3 out brand new mic-input/spliter transformers. Special order from OEP.

Specs:

Ratio 1: 1 +1+1
Max input signal: +22dBu
Consruction: 4 Section winding. Mu metal housing.
Frequency range @ 0dBm: 10Hz -50kHz +/- 0.44dB, 50Hz-50kHz =/- 0.12dB
THD @ 50Hz 0.01% (0dBm)
Primary DC resistance : 83 Ohms +/- 15%
Secondary DC resistance : 89 Ohms +/- 15%
Nominal Inductance: 4H @1kHz 0.1V
Leakage Inductance @1kHz, 0.1V ; 675uH
Interwinding capacitance (primary to secondary) @ 20kHz: 140pF.

 

[flaheu]

Hi Sahib,

I thought that Edcor would not provide any Mu metal shielding ?
By the way, out of curiosity, what did you pay for them ?
I'd like to make an 8 in put splitter.

Thanks

 

[sahib]

Hi Flaheu,

It would not be appropriate to discuss it here but I will PM you.

I was building a 16 input too and to get the minimum order quantity I had to order 100 pcs. The reason that I ordered with 3 secondaries is to be able to use it as a step-up mic-input for a mic-pre too.

But during the process below also came out as a possibility for a simple ms. Normally each channel has 3 split outputs. On pressing the switch you get direct outs from each channel plus sum and diff.

 

[flaheu]

Hi Sahib,

I got your pm, thanks.
But, before I make any decision I would like to know a bit more about the specs.
Not that I'm picky, but I got mitigated experience with edcor in the past concerning quality and sound.
By the way I like the "little" WSM 600/600" which is a great all rounder
How would you "describe" or qualify the sound of that custom model as an output TX and in the above case, as a m/s matrix ?
Is it comparable to the WSM or the XSM serie soundwise ?

Too many question I know  ;D

Regards.

 

[sahib]

Hi Flaheu,

I have no experience with the Edcor WSM600, though Edcor he has a good reputation in general obviously. Therefore I can not make a subjective comparison.

However, fundamentally the WSM600 is for a line level signal and the one I have is for mic-input. So in general we are really dealing with two different animals here.  Mine obviously have a superior mechanical (winding) structure including the MU metal housing.

In terms of maximum input level mine is equal to EDs and that is a big advantage for a mic level transformer. Mine has a better frequency and thd figure on paper.

 

[bruce0]

On the Jensen site, describing their own output transformers:

Line Level General Purpose 1:1 Bifilar Output Transformers
Because they have no Faraday shield, these types are not recommended as input transformers.