[rickcr42]

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No I havne't. You're my first thought when it comes to transformer gurus but I will drop them a line right now!

I appreciate the confidence but it never hurts to get a second opinion.especially when it is straight from the gate and the folks as easy to deal with as they are.

Quote:

Also just reading the other thread I started on headwize after this one didn't take off, what did you mean a load resistor?

that thread did kinda just sit there dying a slow death

The load resistor on the secondary is essential or the primary will see either an infinate load impedance if unloaded or the impedance of whatever is connected which can cause ringing and overshoot due to the mismatch.
If I think of it (

) I will try and dig out some references that explain these things far better than I can.that or just send you the files direct.

good luck man.

rickster

 

[Garbz]

Yes references would be great. Incase it's not blatently obvious i'm not the blind diyer who does what he's told. I love learning things

Anyway the thing is open anyway waiting for a case transplant so i'll simply try this anyway first thing tomorrow.

 

[rickcr42]

I know how that is man.I need to know why not just how-to so i can make my own decisions based on what i know combined with what I have witnessed rather than blindly follow the pack.

"waiting for the case"

I have always had good luck with the Hammond cast enclosure for small audio projects that have either no controls or controls that are a one time set up.Easy to machine,durable,an equivelant available from several sources and offered in a black powder coat finish.

I have a couple of links here for you but will again have to get back.Myy computer is running so damn slow right now i could probably fly out to you and hand deliver the files as fast as my page transition is right now

time for some mych needed maintainance

this puppy shows the difference between SE and BAL hookup and even though a Lundahl file still holds true for other output trafos

http://www.lundahl.se/pdfs/papers/feedbck.pdf

next is the Jensen FAQ.You may have read it,maybe not.Look to the last section for detail on output Z

http://www.jensen-transformers.com/an/an002.pdf

I'll get the other links up as soon as I can actually visit the pages and check content for what you need.I have so many links the descriptions are all abbreviated and not detailed.Keeps things tidy but can be a real pain too.


Rick

 

[Garbz]

The more I read about this the more complicated transformer applications get. The feedback circuit is out of the question since i'm just using a standard line out source I think over the next few days i'll actually go all the way back to how transformers work and do some detailed reading on the topic and play a bit with them.

It's interesting to note all the output circuit examples I've seen show a 600ohm load. Curiosity got the better of me and i measure the input resistance of my amp, which came out at around 600k between +/- and 310k +/- to gnd, so I guess the specs on the balanced input are the same as the single ended according to the datasheet.

This warrents actual fideling

 

[rickcr42]

Seems you are in good shape.Checking specs on all the quadfilar and bifilar line out trafos not a single load resistor needed so the basics secondary direct to XLR to interconnect to input load.

here is a representive Jensen (no man,not ALL have single primary connections

)

http://www.jensen-transformers.com/datashts/123slcf.pdf

If you have access to a scope though you could still check the output with various loads or study the sheets and add parallel resistance at the other end for best response if perfect pulse response is something you are worried about though usually the fix is worse than the disease and the audibility of screwing with phase compensation caps worse than any overshoot-usually

.

something you may find cool,maybe not.

http://www.sowter.co.uk/pdf/GAVS.pdf

Also-have you considered adding a phase reversal switch ? This would be the perfect time and at a cost of only a couple of bucks.

 

[Garbz]

Got it all here. Input selector, output selector, phase switch, and a ground lift. That about covers id

I'm contemplating adding 2 phase switches so the left and right can be independently switched as a quick fix for dodgy speaker wiring or some such nonsence.

Yes I am interested in that article, alhtough it will have to wait for the weekend for a read. I've given serious thought to taking the postgraduate and professional/acedemic route so i'm not afraid of a bit of reading.

Actually the pdf from Jensen came perfectly. I accidently plugged the cdplayer into the volume controlled output when re-assembling the thing after a bit of a mess around. The result was a rather nasty brightness was removed. A bit of tinkering showed that the output impednace was closer to 40ohms then 0ohms on the fixed output line.

A bit of graph reading showed what seems to be the source of all the problems. The Jensen datasheets shows the same freq graph at 0ohms. There's a slight lift at 20k going upwards from there. That combined with the breakup frequency of the tweeters in my system being around 27k would probbaly have an adverse effect on the trebble performance, adding to the shrillness.

The Jensen datasheet came at the right time because I'm just about to pad the input of the transformer with resistors and was contemplating on using 2x24ohms or 1x 50ohm, and the Jensen datasheet seems to recomend isolating the transformer from the ground (using their own inductors no less).

At 50ohms output impednace the 20k is rolled slightly but phase hasn't been effected more then .5-1 degree from 0ohms so that should be the most desirable route. The more and more i'm playing with these the more i'm enjoying them.

 

[rickcr42]

Quote:

Got it all here. Input selector, output selector, phase switch, and a ground lift. That about covers id I'm contemplating adding 2 phase switches so the left and right can be independently switched as a quick fix for dodgy speaker wiring or some such nonsence.

Very cool.The more control you have over your own system the more you can make it do what it is YOU want it to do.And yes i am a total control freak (in all ways

)
a side benefit of this independant L/R phase ":flip" switch is if you have a mono switch in your system and you invert only one channel you can adjust for close perfect system balance (as close as you will ever get

) by adjusting for the least amount of output content.The two channels will to a go extant cancel out beng out of phase and as you rotate a balance control if it gets louder back off until it is at the min.Just thought to toss that out

sounds like you have this puppy licked.


Cool

 

[Garbz]

Yep tried it this morning. Sounds fantastic. Now it's just a matter of going down to the shop and buying a few more switches plugs sockets etc, and assembling it all into a funky looking case.

Thanks for all you help rick. I'll post the final result on the weekend providing i get it all finished aend any bugs irond out.

 

[rickcr42]

"sounds fantastic"


YESSSSSSS !!!!!!!!!!!!

what this is all about man !

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Thanks for all you help rick

enjoyed it dude.every minute of it