High Impedence to Mic Transformer

[Greg]

hi:

I'm looking go the route a transformer based DI input. I'm just looking for suitable options right now. I searched some websites and found that Jensen makes a couple transformers that could do the job, but they're a bit pricey as most Jensen products. I'm just trying to get a small pool of transformers that could do the job, then do some listening tests.

The Jensen models are:
JT-DB-E
JT-DB-EPC

Does OEP or Lundahl make a good high impedence primary tranny?

 

[NewYorkDave]

I don't claim to have a golden ear, and you can laugh if you like, but I have been quite satisfied with the passive Whirlwind Director box. The transformer (TRHL-M) is available as a separate item.
http://www.whirlwindusa.com/trans01.html

Its impedance ratio is quoted as 133:1, which works out to a turns ratio of 11.5:1

 

[Guest]

I think Bo Hansen gave us a few pointers for his DI box
http://www.groupdiy.com/index.php?topic=6108&view=next&sid=a0c1169eed5de0b9b0960377af284393

 

[edanderson]

from OEP, you could try the A262A3E backwards, as a 12.9:1.

and IIRC the whirlwind direct box transformers and horizon direct box transformers are available seperately, mostly to places that make large stage boxes and snakes. so you might try calling redco audio or someplace like that and see what they have available.

you can also try these guys:

http://www.crimsonaudiotransformers.com

they generally serve the OEM market, so they may not want to sell single pieces, but their prices are usually quite good.

ed

 

[clintrubber]

That OEP could give you then 250kOhm, not bad. Unless you go for the 'full 1MOhm' for passive pickups... but I haven't seen passive boxes yet that do 1MOhm.

But then again, active boxes also often settle for around 250k, while 1M would have been easy. Me I'd rather have the 1MOhm (//some pF...) at the cost of slightly more potential noise, but that's a personal preference.

Peter

 

[Gus]

Cinemag

 

[Greg]

Thanks for all the quick info... didn't think of Whirlwind or the Cinemag :thumb:

I have that Bo Hansen schematic on my computer. I'll give that a look over again as well. :green: