 
|
Audio Asylum Thread Printer Get a view of an entire thread on one page |
For Sale Ads |
|
|
Audio Asylum Thread Printer Get a view of an entire thread on one page |
For Sale Ads |
4.244.51.75
In Reply to: Re: would two ohms make a difference? posted by mqracing on May 22, 2006 at 05:57:02:
Mike,
You, of all people, know the parameters needed to make a good choke. I know almost 'nada on iron design, but I SURE have listened to DCR over 25 years and realize fully the importance and benefits of lowest possible DCR in power trannies and chokes. Dr. Charles E. Halijac's unofficial Figure Of Merit of a power supply sums it up well, posted already on this Forum.I have hammered on this low DCR stuff enough here publically - such that SOME people will pop for full 10 HY at 9 ohm "new BFCC." My hope would be that they will tell others and the new market will develop. DowdyLama and Josh would NEVER go back to higher DCR chokes from you, once they actually HEARD what 10 HY at only 9 ohms will do. I'll cut 'ya some slack, 10 HY at 10 ohms is OK too !!
I am FOR you, not opposing you, Michael,..... and am for good audio too !
Jeff Medwin
Follow Ups:
Hi Jeff:You did not give me a complete spec... you said
10 henries with 10 ohms dcr would be nice but did not mention what dc current rating you wanted nor the ac voltage requirements (which effects whether you can use it for a choke input or not)...
but I took some liberty just for the sake of trying....
here is one preliminary candidate...
10 henries at 125 madc and a calculated dcr of 5 ohms
unit would weigh in at about 11 pounds each
unit is designed to carry 400 vrms at 120 hz which should qualify it for choke input service in a large number of applications.
calculated temperature rise of about 15 degrees C
if your fimiliar with the Dynaco Mk III... this transformer would have the same footprint as the 60 watt output trans on the Mk. III.
dimensions would be
overall height 4.5"
overall width 3.75"
overall depth 4.375"mounting width 3"
mounting depth 3.3125"here is an alternative candidate to consider...
candidate B
10 henries at 125 madc and 52 ohms of DCR
weight would be approx 2.75 pounds (in channel frame)
unit is designed to carry 400 vrms at 120 hz which should qualify it for choke input service in a large number of applications.
calculate temp rise of 24 degrees C
unit would occupy far less space than candidate A... mounting centers in channel frame is 2.8125" overall height would be approcx 2.5"
to use the dyanco illustration as I did for candidate A... this guy would be approx the same size as the output transformer on a ST 35 or SCA-35.
So how do the two candidates compare with each other??? Listed below are some things I noticed.
B has a little bit more current clipping headroom than A.B operates at a little bit less overall flux density than A.
B produces a smidgen more calculated inductance than A...
the relative perm of B is much, much, much lower... it's relative perm is only 26.6% of the relative perm of candidate A.
B has a moreso equal distribution of copper and core losses compared to candidate A. Though the copper circuit losses in A were less than the copper losses in B. The iron losses in A were signficantly higher and made up the lions share of it's total losses... whereas candidate B comes very close to a 50/50 distribution of copper and core losses.
And the overall losses in B (calculated in watts) are approx 40 percent less than transformer A.... making it more efficient.Candidate B would cost about half the mullah than candidate A.
I'd be happy to build either unit if there were a sustainable market for either one or both.
msl
This post is made possible by the generous support of people like you and our sponsors:
Top of Page ]
[ Contact Us ]
[ Support/Wish List ]
[ Copyright © 2025, Audio Asylum, all rights reserved ]
