DC Filament satisfaction

pfontana · 1550

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Offline pfontana

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on: June 03, 2020, 07:18:58 PM
Hi All,
I've been thoroughly enjoying my Kaiju 300B and Jaeger speakers.  Speakers have around 100 hours and Kaiju 200 hours, so relatively new.
I waited to upgrade the Kaiju until a few days ago.  I added the DC Filament.
Everything is dead quiet at rest now.  But.... the music sounds a little harsher.  Again, the system sounded really good with stock build.  Should I give this time?  Any other adjustments/measurements to take?  Comes down to personal preference?
I'm certainly happy to let it break in further.
Thanks again,

Offline Doc B.

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Reply #1 on: June 04, 2020, 05:49:50 AM
Check to see if it sound the same at different listening levels. If it only does this at high volume it may just be compression from pushing the amps. If it does it at any level it's probably worth running it in a bit more an re-evaluating. It's not a thing I have noticed when adding the DC fil supply to my setup, so that's about the best I can offer.

Dan "Doc B." Schmalle
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Bottlehead Corp.

Offline Bobinsms112

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Reply #2 on: June 06, 2020, 04:19:26 AM
I found a little of the magic went away when going to DC, but you what you gain is dead quiet.  Everything is a trade off in audio it seems.  I did find that the DC kit took some time to break in and gradually started to sound better.  I've been experimenting with tubes too, and found a pair of 300B's recently that gained a lot of the magic back.  It's all part of the hobby for me.  Love this amp!

Offline pfontana

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Reply #3 on: June 06, 2020, 09:55:51 AM
Thanks for the comment.  I also am recognizing the tradeoffs!  It is part of the fun for me to make upgrades.  Solving the perfect equation of music reproduction is something I'm in no hurry to finish.
I'm letting the DC upgrade break-in.  I played with speaker placement, which oddly was different for AC stock build.  This brought back a little liveliness.  Time I think will bring back more.  Tubes, caps, upgrades will come later of course!
Thanks again for the comment, much appreciated.

Offline Natural Sound

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Reply #4 on: June 07, 2020, 09:54:20 AM
From what I've heard over the years I prefer the sound of AC heaters in general. BUT. A lot of it has to do with the speaker sensitivity, the amount of hum the amp produces, how close you sit to the speakers, etc. And I'll add that it also depends on how much hum you can tolerate and how long your system is idle. As in not playing music. I'm certainly no expert on the subject but according to the Klipsch product support page the difference between a speaker rated at 90 dB sensitivity and 110 dB is one hundred times the output of a loudspeaker. Someone may jump in here and correct that but lets go with that assumption for now. You may not hear any or very little hum from AC heated filaments on the 90 dB speaker. But on the 110 dB rated speaker the amount of hum produced by AC heaters may be unbearable. The Jager is moderately sensitive at 94dB. Certainly a lot better than big box speaker ratings of 88 dB. But I wouldn't expect hum to be a huge issue unless you wanted them to be dead silent.

Please note that my thoughts above are based solely on the numbers and what I've gleaned as [clears throat] "knowledge" over the years. Often times the numbers do not relate to what my ears are hearing though.

I'd second the recommendation from Doc B. He knows a lot more about this stuff than I do. Let the DC mod "burn in" for a while before doing any critical listening. Electronic components take a while to reach full potential sometimes.

Here is the website that describes the numbers I was talking about if you are interested.


Offline bernieclub

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Reply #5 on: June 07, 2020, 10:28:40 AM
I listened to the A/C filaments for about two months, then installed the kit.   I notice that it takes a lot longer for the amp to warm up and "sound right" with the D/C.    Forty minutes vs. fifteen or so.

Bernie Zitomer


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Reply #6 on: June 07, 2020, 11:09:24 AM
I wonder whether the DC filament supply mod has lowered the noise floor of the amp, revealing "harshness" that was already there in the signal but was previously inaudible b/c it was buried in the noise floor.  If so, this suggests a silver lining: the amp is now more resolving, and if Philip can hunt down the source of, or otherwise ameliorate, the harshness, he may have an even *better* sounding system.  I'd start by looking at the source and pre-amp. Even the interconnect cables might make a difference (fairly easy to diy with different wire gauges, wire compositions, shielding vs. no-shielding). Or perhaps, lastly, a different set of 300Bs.

cheers, Derek

Offline Paul Birkeland

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Reply #7 on: June 08, 2020, 06:10:45 AM
Without the DC filament supply, the mains AC frequency on the filaments adds little sidebands to whatever content the amp is playing.  These disappear with the addition of the DC filament supply, which I find to be a good thing, but it is something that sounds a bit different.  I've attached the first image I came across on Google Images that shows the appearance of sidebands.  These are way down because the DHT in question is running DC on the filaments.  They would be far, far more pronounced on an AC heated Kaiju.

Paul "PB" Birkeland

Bottlehead Grunt & The Repro Man

Offline pfontana

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Reply #8 on: July 06, 2020, 07:36:38 PM
Hi All,
I'm revising my original opinion of the DC filament.  I upgraded a few of the caps on the amp and tried a different set of 300Bs.  I did each upgrade separately and waited around a week and a half before making the next change.  Dialing in the amp in with each upgrade has made all the difference.
The DC filament upgrade is definitely worth it for me and I'm glad I did it.
Upgraded, and in order, for those interested...
.1uF Miflex KPCU 0.10uF 600VDC Copper foil Poly/Paper in Oil
300B tubes, JJ Electronic
10uF Jantzen Silver Z-Cap, 10.00µF 800VDC


Offline mcandmar

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Reply #9 on: July 06, 2020, 11:50:37 PM
I've attached the first image I came across on Google Images that shows the appearance of sidebands.  These are way down because the DHT in question is running DC on the filaments.

Knowing Bartola that amp will be using Rod Colemans filament regulators, which are basically a regulated current source supply.

It sounds a bit like the Crack with or without the Speedball debate to me.  A regulated DC supply is going to clean up the amp considerably, yet some people just prefer the stock Crack.  Certainly with a harsh sounding source as its going to become all the more noticable.

Two things people swear by when using DHT regulators, use a CLC supply before it which the Kaiju has, and use a quality capacitor before the regulator.  Something like Nichicon FW or KW.  Never tested the theory myself, but for the cost of a few caps it might be worth experimenting with.