Balanced Inputs

[Deke609]

I'll be putting a Beepre in front of my SII, and plan on doing the input transformer mod documented by JH.

Questions: can the same or similar mod be made to the SII? (leaving aside the top-side space limitation challenge)?  If it can be made, would the same Cinemag transformers used in the Beepre mod work for the SII, or do I need something different?  If different transformers are needed, could you suggest something (or let me know the required specs)?

I think it would be interesting to compare  balanced and unbalanced configurations of the BeePre and SII - my DAC does both balanced and unbalanced out.

Many thanks,

Derek

[Paul Birkeland]

At least use Cinemags or Sowters for input transformers, we don't recommend the Hammond units.

Using input transformers between the BeePre and Stereomour is unilkely to be of any use.  You can cut up a pair of interconnects and solder them to a pair of octal sockets, then try some altec 15335 transformers to get a feel for the differences.

[Deke609]

Thanks PB.

At least use Cinemags or Sowters for input transformers, we don't recommend the Hammond units. 

I'd use whatever you recommend as best.  I noticed that in early Beepre threads you had recommended a Sowter product, but the mod document from JH lists a Cinemag. I looked at the Cinemag transformer and it looks pretty cool - it's available with a double Faraday shield.

Using input transformers between the BeePre and Stereomour is unilkely to be of any use. 

Is that b/c balanced inputs to the SII won't do much? Or b/c there is a simpler way of implementing balanced inputs on the SII that doesn't involve input transformers?

Many thanks,

Derek

[Paul Birkeland]

I'm not familiar with the JH document.  I'm only aware of one other person who put input transformers on their BeePre, and they used Hammond transformers that didn't fit the holes we provide.

The Sowter 3575 looks like a nice choice. 

Using the XLR balanced output on the BeePre and input transformers on the S2 just adds a transformer that doesn't need to be there (you can also use the input transformers with RCA cables).

[Deke609]

Thanks PB.

Here's the JH document posted on this forum: https://bottlehead.com/bee-pre-input-transformer-modification/

I don't understand why I wouldn't use an XLR input from the BeePre XLR output - but I understand nothing about this stuff, so I'm going to read up on it a bit and come back with questions later.

cheers and thanks,

Derek

[Paul Birkeland]

Ah, "JH" is Josh Harris.  Yes, he and I documented that with my BeePre.

I would recommend reading up, especially the white papers on the Jensen transformer website.  There's a lot of misinformation and subtleties that get thrown around in the name of marketing, and it can be a lot to sort through!

http://www.jensen-transformers.com/application-notes/
It is worth registering so you can read through these. 2, 3, and 9 will probably be the most helpful.

[Deke609]

Many thanks PB.  That's very helpful. I'll review the Jensen materials as you suggest.