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In Reply to: Updating & Refining the " DCR " Topic posted by drlowmu on March 7, 2007 at 12:10:47:
Dear All,I remember three things:
- Henry P came with a ‘plausible’ explanation as to why low H (first) choke(s) might be beneficial (the flywheel concept);
- That the DCR of the PT played an important role in this explenation;
- That Henry P ordered some stuff and started building a low H / low DCR supply.
I didn’t hear from Henry P since. He might be too busy listening...If you are out there Henry, any results yet?
Follow Ups:
IIRC the important thing was the relationship between the choke and the following cap (which is load dependent). The DCR of the transformer wasn't the biggie.The results of the simulations were interesting. They allowed the first cap to be charged to more than the normal max of 1.4 times the secondary rms voltage. Some wild voltages in the choke troubled me but Henry felt they were a limitation of Duncan's simulation. I got sidetracked by speakers and dropped the matter. I would love to hear if Henry is building his amp.
Many of the things in Jeff's post are common practice. It is just a matter of degrees. Extra current in a PT is always desired and we do use caps that are small for the task at hand (because we want to avoid electrolytic capacitors). We perceive the results as a "faster" amp with "tighter" bass (my best attempt at audiospeak). I might beg to differ on rectifiers but I did just admit to liking the 5u4. And CCS, IT, and choke loading is in favor which reflects the "high dcr load" part.
So perhaps it is the low henry first choke that is deemed too radical around here? Small value line reactors are common place solutions in industrial circuits. Then you have those who report good results with having a choke (instead of a cap) as the last filter element (should we be returning at power supply caps?). Maybe the impedance of the power supply isn't the ticket?
Dear Russ,The low DCR of the PT was indeed not the 'biggie', but I remember that Henry pointed out the a low DCR PT 'helps' to get the flyhweel spinning.
I can't find the exact post now, but look at his simulations where he uses low DCR PT's. If you increase the DCR of the PT, than the 'flywheel effect' ( C1 voltage rises above T1 voltage) dissapears.
or password protected. I'm not sure those posts were the REAL Henry. The one we dearly love and miss. =:-0Was the original Henry posting from Boston or New York?
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Boo!
as I am sure others did. The posts were in keeping with the emails. The sims I ran were as well.Ivan I have read enough of your posts to see that you have experience with better quality equipment. Not everyone has. When you get into more serious gear, details, which are basically unimportant in lesser designs, can become "make and break" things. For example Bud (O-Netic’s designer) posted down below how much difference the wire for the ground bus made. I can't say my stuff has reached the level where litz wire on the ground buss is a "make or break" item. So it would be easy to dismiss such a statement. But IMHO that is a recipe to insure my designs never reach that level of performance.
I suppose in the end it is all about whose opinions one puts trust in and if what they are saying has any basis of truth with regards to your own work. I think it is fair to say that many things, which we know effect sound, can’t be defended solely by electrical principles or normal measurements. However it sure is nice when you know “why” something sounds better.
he certainly could have benefited from one!As one who both knows and likes Dennis, and has heard his amps a number of times and has actually met dr lowmu and found him to be quite a nice fellow, I try to stay out of all of this.
I’ve heard many of the amps that are supposed to be “legendary” and have met and know many of the better builders, having attended about a dozen CES’s, a couple VSAC’s and all of the RMAF’s plus a Stereophile show or two.
All that said doesn’t really mean much in the larger context, because my taste in audio might not be the same as anyone who posts here.
What I am sure of after all of this is that there is a shred of truth in many of these things from low DCR power supplies to silver capacitors.
I had the pleasure to meet Kondo San at CES many years ago and again shortly before his death at last years (2006) CES. I feel that musical reproduction is far more than just engineering theory but I also do not feel an obligation to defend my opinions to others who may or may not have had the good fortune to hear all that I have been blessed to hear.
The most sensitive measuring device is not a scope or a spectrum analyzer or even our ears. It’s our heart.
Whatever piece of audio gear allows the music to reach our soul and trigger an emotional response is Ultra Hi-Fi or whatever you wish to call it. If you do not agree it matters not a whit to me, as ones experiences in the area of a very personal nature to be shared with friends, if at all.
to expound a bit on your system and how you came to decide it was right for you?
and the decisions were easy.It didn't cost much money, I could do most of the work myself, and it sounds pretty good to my ears.
But sadly, it's not Ultra-Fi. :-(
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