[Lazarus Short]

At a garage sale some time ago, I bought a Radio Shack interconnect cable pair, and besides being paired together, there was a plastic can in the middle of the run. The sticker on the can indicated that it contained a transformer, as there was a diagram of two sets of windings. It was intended to prevent ground loops, but I wondered how it would affect the sound, knowing what effect a transformer has in an amp. I was putting my AV system together again (TV/DVDP/amp/speakers) and decided to try it out. The sound seemed softer, more natural, but I have not done any A/B testing. Maybe at the next meet.

Anybody else have any experience with this type of IC?

 

[Steve Eddy]

Don't have any experience with that type of interconnect, but do have a lot of experience with transformers and in my opinion, a good quality transformer is one of the most transparent devices around in addition to other unique qualities such as galvanic isolation.

I don't recall Radio Shack ever making such a cable, unless it was something aimed at the car audio crowd. And I don't imagine the transformer in the cable is of very high quality. Though even poorer quality transformers can sound amazingly good.

se

 

[scootermafia]

Careful! It's a robot in disguise.

 

[Steve Eddy]

Quote:

Originally Posted by scootermafia /img/forum/go_quote.gif Careful! It's a robot in disguise.

se

 

[Lazarus Short]

Quote:

Originally Posted by scootermafia /img/forum/go_quote.gif Careful! It's a robot in disguise.

You're...funny!

 

[Paul J.]

That would seem useful in breaking up ground loops, but there are probably much better ways to attack it. I can't imagine the transformer is anything but detrimental. If it sounds better in some way, it is probably because it is restrict the bandwidth in a way that reduces noise on increases dynamic power. Price some good 1:1 line audio transformers, and you'll see that what RS included can't be that good. Still, a really unique find. I wish I had a set. . .

Paul

 

[Lazarus Short]

Quote:

Originally Posted by Paul J. /img/forum/go_quote.gif Price some good 1:1 line audio transformers, and you'll see that what RS included can't be that good.

Now I'm even more intrigued.

 

[Steve Eddy]

Hey, I've seen that burro before!

Paul J. here is from Wild Burro Audio.

Check 'em out!

Wild Burro Audio Labs

Disclaimer: I have no affiliation with nor am I even acquainted with Paul. I came across WBAL over on diyAudio and he seems to be doing what he can to provide a good quality, reasonably priced, US made product and thought he could use a plug.

se

 

[Paul J.]

I am indeed that guy. I don't sell transformers though, so don't think I'm biased! On that front:

You can buy a 1:1 line level transformer for under $10 (I think, I don't have a link). However, a "basic" Lundahl LL1527 will run you $67, while their "best" the LL7902 will set you back $235. Remember that you need a stereo pair! I don't know for sure, but I bet if you asked them for an isolation transformer for a high quality audio application, their recommendation would be either that $235 unit, or something close to it. Lundahl is certainly not the most expensive winder either, they tend to be pretty reasonable!

Then, ask yourself, if a $10 transformer works fine, why would anyone need a $235 one? Remember, this $235 unit isn't for tweaky über-high end stuff, it's just the right piece for good audio (which is surely what all of us on this board are after!). The answer is that the $10 unit wouldn't really work fine. It would be very bandwidth limited (softer?) and might introduce some nasty phase problems and high frequency resonance.

Here's an example of where those IC's would be handy: You've got a grounded preamp/amp and you introduce a subwoofer connected at line level. Many sub plate amps are grounded. Then you've got a loop, and probably a 60hz hum that gives you fits. Some would "float" one of the grounds (I have), but that is a safety breach. The better solution is to leave the earth ground bonded firmly to the chassis of one of the units but insert a resistor between the safety earth and signal grounds. The difference in potential will probably kill the hum. But, if you aren't comfortable with modding your grounding scheme and you don't want to compromise safety of your system, using the IC's with the transformer will also solve your problem. Provided, of course, you've still got enough bandwidth to be satisfied with your sub! (Though given the relatively lower demands of resolution, if the IC's are transparent anywhere, it will probably be here).

The other common ground loop problem stems from CATV connections. But, the best way to solve those (IMO) is with an isolation transformer on the CATV line.

Which isn't to say that I wouldn't enjoy playing with those IC's. I like toys. That's why I sell a few speakers!

Paul

 

[Steve Eddy]

Quote:

Originally Posted by Paul J. /img/forum/go_quote.gif You can buy a 1:1 line level transformer for under $10 (I think, I don't have a link).

Can get cheapie $10 trannies from Edcor

Quote:

However, a "basic" Lundahl LL1527 will run you $67, while their "best" the LL7902 will set you back $235. Remember that you need a stereo pair! I don't know for sure, but I bet if you asked them for an isolation transformer for a high quality audio application, their recommendation would be either that $235 unit, or something close to it. Lundahl is certainly not the most expensive winder either, they tend to be pretty reasonable!

Personally, I'll take a CineMag CMLI-15/15B over the LL7902 any day. And it costs less than the LL1527.

Quote:

Remember, this $235 unit isn't for tweaky über-high end stuff...

For that price it had better be.

se