Speaker Selection : Studio Monitor and cure for RFI into it Thanks for help...

k3Tim

Wanted to take a moment to thank the group for several helpful items.  Several suggested using a Studio Monitor for the speaker system and this proved an excellent suggestion.  I was using a (vacuum tube) based Guitar Amp as speaker but have switched to a JBL studio monitor.The studio monitors are in fact an excellent speaker. 

Also, was having a difficult time with RF into the speaker system, both before and after the change up.  The JBL has a balanced input and after reading on the group about the ground loops an audio transformer was wired to convert the unbalanced (ACC PORT) output to balanced. This did the trick - no RF into speaker now.  (In AM mode it was like a monitor function but for SSB was very distracting.)

I went with this :

http://www.allelectronics.com/make-a-store/item/tctx-17/coupling-transformer-600-365-ohms/1.html

transformer and seems to work okay (low imp side towards the flex port).  Anyone have an opinion on that and using it for the conversion of Unbal 2 Bal?   An audio transformer from Hammond would do, but at a higher cost.

Thanks,

Tim  / k3Tim/6

Jay Nation

Tim 
I had ground loop problems with just the line-out to line-in connections. I'm just connecting the Flex line-out to my PC soundcards line-in. Since I didn't need to convert from unbalanced to balanced, I found a fairly cheap solution that's working well. Without the isolator, I had both ground loop and RF problems, using just a straight line cord. With these isolators I don't have either problem.

 http://www.monoprice.com/product?p_id=6909

4 seperate 1:1 transformers/channels per unit.

But I just bookmarked your find too.

73, Jay - NO5J
 

k3Tim

Hi Jay,

That looks very good, connectors and ready to go at a  good price point.

I've BM that...

Thanks,

k3Tim / 6

Jay Nation

The price is cheap and and when you get them in front of you, they will look cheap too, They get the job done, and the assembly is nicer looking than I'd produce homebrew. They won't satisfy audio connoisseurs but they are functional and the noise is gone. I bought several to interconnect 3 pcs and my ham gear none have failed, I'm planning to buy more when I place my next monoprice cheap audio cable order.
73, Jay - NO5J   

Jay Nation

In case anyone goes poking around on the monoprice website looking for 3.5mm to RCA male or female Y adapters to use with these things, the Premium Adapters are heavy-duty, but the 3.5mm end is way to chunky to plug in, side by side into the Standard PC motherboard sound card backplane panel. I bought them anyway.
On the PC end I also use a 3' x 3.5mm headphone extension cable which has the smaller male end on it these might also help should you need to wrap the cable around a ferrite. They are also handy for rerouting the plugging and unplugging around to the front side of the PC. Monoprice has those too. Also take note that on the isolators, one side has female RCA connectors and the other side has male RCA connectors, so be sure to select the correct Y-adapters. It's hard to know what your getting sometimes when buying online. Monoprices pictures have matched what they've shipped me so far.

Now that RadioShack is no more, Monoprice has a lot of the little goodies you can't find locally anymore. 

73, Jay - NO5J