Mcandmars ramblings \ build thread...

Hi,
The RESISTOR that will be  for  C1 to C3 and C2 to C3  to reduced the noise can i use any type of 100R 1/2W or do you have any recommendations?

Thank You!
 
I finished replacing the 0R1 5W resistor that i screwed up while i was installing the 2 100R on C1 and C2.The reisistor mod works,No hum with the Q7X1/DT8XX 600R and HD6XX  but i still have slight HUM when using a 24 ohms headphone.I'am thinking of installing a CHOKE will this MOD help to lower the HUM?

THANKS!
 
What are the 24 ohms headphones you are using?    Interested to see what kind of sensitivity they have, for example IEM's just aren't going to fly.

The chokes can help a bit, but nowhere near as much as the resistor mod for eradicating hum.  The chokes seem to me more effective at higher frequency's to lower the noise floor and give a blacker background.  I cant really recommend them as a cure for hum due to the cost and hassle of trying to mount them.

I made many small tweaks which all helped in there own small way to quieten down the amp, i believe replacing the audio path input/output wiring helped greatly in that area. Its hard for me to say really as i did a mini rebuild and replaced so many components and bits of wiring at once i cant single out the difference each made.  It is also entirely possible you just have a slightly noisy set of tubes, is the hum the same on both channels?  and does it move if you switch the tubes around? 
 
I used Sony XB700 and Audio-Technica M30 with XB700 it's more hum than with M30 even with 4R tap still humming but it's very very low you really need to listened to it.My wife and my kid can't hear the hum until i told them so it's not bad at all and it's not affected by the volume pot so that is the good thing.It is dead quiet with Q701,DT880 600R and the HD650 the resistor MOD helps a lot to reduced the HUM.I can even used the 32R tap with higher impedance HP with very little HUM.It only bugs me because i was the one who build it and know that the hum is there other than that if don't let anyone know about the hum while they are listening to it they would not noticed.For the CHOKE i'am still planning to put a pair for $12 a piece it's not bad the only thing is where to mount it.


THANKS!
 
Sony 106 (dB/mW) 24 ohm
Audio Technica 100 (dB/mW) 65 ohm

Those Sonys are sensitive alright. The Chokes may well give you that little edge you need, provided what you are hearing is coming from the HV supply.  Just keep in mind placment of the chokes is critical so they dont pickup, or interfere with any other iron inside the chassis.  I found the position i am using worked really well in that regard, which is just as well as i really didnt have any other options that would fit inside the wood base.

Not sure how up to date the thread pics are so here are a few pics of the current layout, getting the soldering iron in to mount the caps was a real challenge!

 

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Yeah i don't think if i can install the choke that way.
I will be upgrading the 1.5uf and the 0.1 caps next week so i will see if i can move stuff around to accommodate the choke.
http://cdn.head-fi.org/0/0f/200x200px-ZC-0f5f840a_DSC_3474.jpeg

THANKS!
 
Yes the original 1.5 still there i will be replacing it with a 1.5 Mundorf.The big 2 caps  is the replacement for the 22uf.
 
Novelty Caps: Gudeman paper in oil

When i found these oddballs on eBay i just had to have them. They are a paper in oil construction housed inside a hermetically sealed glass enclosure, rated at .1uf 5000vdc.  I've had these on my desk for a few months which provided constant amusement watching the air pocket slowly move around inside the glass, and i mean slow as it takes hours for anything to happen. I don’t know why but i found that oddly amusing.

I have no idea what these were originally intended for as there cant be too many applications requiring 4-5kv rated caps.  I haven’t been able to find very much information about Gudeman as a company other than they were based out of Chicago Illinois and produced a whole range of paper/oil caps around the 1950's and 60's.  They also seem very popular with the vintage Guitar community in tone circuitry, but little to no information was found regarding these glass cased high voltage caps.

On my capacitor testers both of these measure exactly .1uf and have no leakage up to 450v dc so they are still perfectly healthy.  With that in mind i removed the Russian Teflon FT-3's from my S.E.X. amp to see how they perform.  My expectation going from a Teflon capacitor to a Paper/Oil was a rolled off high end, and a thicker sounding presentation through the midrange.  Certainly that has been my experience in the past with different Russian PIO flavors. That is not really what i found at all, there is an almost imperceptible difference in high end detail vs the teflons, the midrange is very similar with maybe a tiny bit more warmth and smoothing, and a noticeably less rolled off low end.  I was expecting this to be a quick experiment before i soldered the FT3's back in but instead i found myself sitting up straight and paying attention.

The first big difference i have noticed is how much energy there is dynamically making the FT3's sound thin and weak in comparison. Movies with a recorded low frequency effects sound channel "LFE" have real powerful energy behind them now.  Its not a case of an over emphasized or overpowering low end, but more a realization of how much of the impact i was missing before.  If a kick drum goes thump, it goes thump!, not a bump.

The other big difference, and the one that has surprised me the most is its almost holographic presentation of the music. If you have ever heard a binaural recording where the soundstage has moved outside your expected boundaries to the point of startling you, that is kind of what i am experiencing. I have been listening to these caps for days now with different headphones and music and i still can’t wrap my head around what i am hearing, there are layers and depth of instrument separation and positioning that just wasn’t there before.  I just can’t seem to rationalize it which is driving me nuts, but on the other hand i have been rediscovering my entire music collection again and loving it.

Is it possible the FT-3's aren’t really as good as everybody makes them out to be?  or have i just stumbled across something rather special?  or gone a little insane?
 

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I put a pair of these, 8kV rated, in the power supply for my electrostatic speakers; in the power supply.  Mine were bright red. 

Of course, they never gave a moment's problem.  The cheap mica caps that Infinity put in parallel/series to double the voltage rating were very unreliable.  That is less than a dollar for the caps in a $2000 speaker system.  Cheap asses!  Bottlehead wouldn't do that.
 
Interesting, they say with most audio equipment you are listening to the power supply, i suppose the same is also true for electrostatic speakers.  They sound like an interesting pair of speakers, i thought you were using a full Blumenstein setup?

I am still deeply impressed with these capacitors. I also picked up a pair of Jupiter paper/wax .1uf 600v caps for a steal recently so they should make for an interesting comparison.  I am a little concerned about the chassis heat despite the fact they have the same temperature rating as the Mundorfs of 70c.  More as it happens..

 
The Servo-Static I was an interesting speaker.  It was electrostatic from 100 Hz up.  It had the first commercial subwoofer with motional feedback.  It came with a three way crossover/servo sub amplifier.  It took two more power amps to run them.
 
Motional feedback is an interesting concept i had never heard of before, complex looking circuitry mind you!
 
It is old.  Many, maybe most, of the subs marketed for high end audio today use some feedback from the cone to the amp to correct its motion.  It is so widely used that it is hardly mentioned.

The SS-1 came out in 1969.
 
Fancy Caps: Jupiter HT Paper BeesWax .1uf 600v

HT are the "High Temperature" range suitable for valve amps. I have heard of potential issues with these failing due to heat, but they are rated for 70c which happens to be the same as the Mundorf Silver Oil range i am using in the output stage.  They do have to endure 30-40c inside the S.E.X. amp so time will tell how well they last.

Manufacturers blurb:
A unique blend of the old sound with refinements of the new. New high temp (HT) series replaces the original beeswax/paper design (3rd generation design). Jupiter Condenser HT line of capacitors feature a reinforced beeswax paper dielectric and (with further improved impregnation techniques) is now cased in a non-drip/melt casing and can withstand higher operating temperatures. Perfect for DIY and OEM use where natural sound is demanded.

The "new look" to Jupiter Condenser Co. capacitors, is true to form following function. Not just a new style, the outer casing is still true to natural materials yet offers improved environmental characteristics. A paper tube impregnated with phenolic resin assures excellent moisture resistance along with a resin end fill to lock moisture out. The casing material will not melt or drip even at higher temperatures.

For productions, a computer controlled wax vacuum impregnation system was engineered and built by Jupiter Condenser, and section processing is based on techniques developed by Western Electric and RCA. This is capable of deep vacuum and high pressure, providing consistent impregnation with more gas and moisture removal. New proprietary measures of strengthening dielectric properties have been developed and employed which yield higher insulation resistance and allow greater operating temperatures. Wax and paper construction yields a very well mechanically damped capacitor, free from electrostatic and mechanical ringing.
Specifications:

    Tolerance ±5% standard
    Rated voltage 600Vdc - Tested at 1200VDC at two stages of production
    Pure silver leadouts 20 AWG (0.812mm dia.)
    Max temperature +70°C
    Beeswax impregnated Paper dielectric
    Aluminum Foil electrode material

Normally i wouldn't have considered a "premium" capacitor such as these but i managed to pick up these two for less than half their retail price, an offer too good to pass up. They are clearly superior to the FT-3's so a side by side comparison is a bit pointless, vs the Gudeman oils however there is less of a difference.  The two are very similar but i would have to say the Gudemans have a larger, bigger sound to me.  i.e. more dynamic, and energetic sounding.  The Jupiters are a little bit more restrained, but have better tone/detail and a clearer high end.  I have switched between the two twice at this stage and still cant make up my mind which to keep in there.  Gudemans are more fun, but i suspect the Jupiters are technically more correct if that makes sense.

Are they worth the premium price new?  They are listed for @£22 or $33 each so if that doesn't scare you off then i can highly recommend them.  They are also tiny at 14x25mm!
 

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