Jensen Copper Foil In Oil Capacitors

0 Members and 1 Guest are viewing this topic. Read 11977 times.


Jensen Copper Foil In Oil Capacitors
« on: 2 Aug 2003, 03:34 am »
I debated on weather to post this here or in the LAB since it's a review of a DIY type component/mod. Obviously the Critic's Circle won... :)

I installed a pair of Jensen copper foil in oil coupling caps in my preamp (Transcendent Grounded Grid) this week and have been amazed at the presentation. By presentation I mean how the music is presented rather than specific portions of the audio spectrum.

First and foremost the system sounds more like a musical event than a reproduction. The music seems freer and less tied to the speakers. The speakers (Vandersteen 3A sigs) already did the disappearing act very well and imaging in my living room is spacious and deep. The addition of the Jensen's enhanced this effect and brought out the subtle spacial queues that help transport the listener to the performance. This is especially true on live performances. However, even studio recordings seem less like a recording and more like live music. It obviously doesn't sound like a real performance (no system I have ever heard does) but it's certainly closer than before.

As for specific sonic areas; the bass is deep and tight, I had to turn my subs down a bit; the midrange, particularly vocals, is very smooth but with plenty of bite if the music contains it. Listening to the Ray Brown Trio, Summer Wind this evening I was struck by the clarity of the piano. Both the sound of the hammers hitting the strings and by the complex harmonics and resonance of the instrument. One area which I am not completely happy with is the higher frequencies. Reproduction of cymbals seems slightly fuzzy. Not bad but not as clean as other coupling caps I have tried. This may be a break-in issue as I'm sure it will take some time for them to fully form. I did break them in on the bench for a week but at a fairly low voltage compared to what they see in the preamp.

Even with the slight reservation on the very top frequencies the overall sound is, IMO, very good. The kind where you just think, "damn this sounds good" while listening to music.

While these caps are not inexpensive ($24.60 ea for 1uF/630V) they are certainly cheaper than the majority of cables and many other tweaks out there. I approached this mod with a jaded attitude as I have tried Auricaps, Axon, Solen and some inexpensive Xicon metalized film/polypropylene caps in this preamp and found the cheap Xicon's to provide the best sound. I put off buying the Jensen caps for months because of less than good results with the aforementioned caps. Now that they are in the system I am delighted with them, especially if the top end improves a bit.

If you have a tube preamp and don't mind getting out the soldering iron, these are certainly worth a try. IMO, there are not many things for $50 that you can add to your system that will provide the improvement I saw with the Jensen's. One caveat is the size, these are large capacitors, about the size of a D-Cell battery.

Associated gear:
Transcendent Grounded Grid. The GG has a DACT attenuator, HEXFRED's, bypass caps on the audio board, damping mods, NOS Mullard's wearing Herbies Halo's and of course the Jensen's. The feedback has also been reduced by about 3dB.
Philips SACD 1000 with much damping compound, BG caps, LC Audio ZapFilter output stage.
DIY low capacitance shielded cables terminated with Bullet Plugs
Odyssey Xtreme Mono's (the only things without mods - for now...)
Music Hall MMF-5 with added damping to upper plinth, Mogami cables, Grado Statement Platinum, Herbies "Way Excellent Turntable Mat"
Hagerman Cornet built as the "premium" version.
Vandersteen 3A signature's and 2 Vandersteen 2Wq subs.
Amps fed by BPT 2.5 Ultra, all other gear fed by BPT BP-4, each piece has it's own circuit. The BPT's are plugged into an Acme silver plated, cryo treated outlet. Power cords from the BPT's to the gear are all DIY based on the Bob Crump recipe.

Happy modding!



Jensen Copper Foil In Oil Capacitors
« Reply #1 on: 3 Aug 2003, 07:14 pm »
So you didn't like the Auricaps? I switched the .1 uf Wima caps in my tube pre to the Auri's and found a great improvement. Most prominent was the tight bass responce-absolutely eliminated the bit of boominess that was present b4 the swap. I actually thought that I had a standing wave issue in my room. Perhaps I should try the Jensen's. I'm sure the small value that I need would be less expensive. By the way, are these coupling caps in your pre?


Jensen Copper Foil In Oil Capacitors
« Reply #2 on: 3 Aug 2003, 09:50 pm »

Yes, I tried the Jensen's in my preamp and I didn't like the Auricap's in that particular piece of gear. I do have them in my phono preamp and in some tube amps I built and I like them very much there.

When I tried the Auricap's in the preamp I experieced the opposite of what you did. I had somewhat wooly, indistinct bass with the Auricap's  in place.

I have seen others say that the Auricap's are not the best choice in circuits where they don't have much DC bias. This somewhat mirrors my experience. The preamp only has about 70V of DC bias on the coupling caps while the phono stage is somewhere around 120V and my tube amps are over 300. They work great in both of those pieces just not so well in the preamp. Another one of those areas where trial and error may be required for the best results. :)

Addendum to review: The small amount of fuzziness in the treble I mentioned is going away and the preamp is sounding better each day.



  • Newbie
  • Posts: 1
Jensen Copper Foil In Oil Capacitors
« Reply #3 on: 5 Aug 2003, 10:10 pm »
Hi mgalusha
How are things going?
Did you build your Grounded Grid from scratch or kit?
I too own a Grounded Grid but in kit form.
I tried the Jensen Copper PIOs in the GG and really liked them very much.I started of with the stock Solens,then came the Jensens.Unfortunately,after about 8months of usage,the Jensens started to hiss,and from there i switched to the Auricaps and thought that the Auricaps sounded a little more dry,not as nice as the Jensens.
I ve read some posts arguing the reliability of Jensen PIO caps manufactured before 2002 or something like that(mine was 2001,i believe with the codes on the caps).
I m waiting for the new Jupiter Copper beeswax caps,and in the meantime i think i ll just stick to the Auricaps.
What 12AU7 valves are you using in the GG?

Bill Baker

  • Industry Participant
  • Posts: 4853
  • Musica Bella Audio - Custom Design and Manufacturi
    • Musica Bella Audio
Jensen Copper Foil In Oil Capacitors
« Reply #4 on: 6 Aug 2003, 01:46 am »
"Yes, I tried the Jensen's in my preamp and I didn't like the Auricap's in that particular piece of gear. I do have them in my phono preamp and in some tube amps I built and I like them very much there. "

  Very well said. It's nice to see that some people realize that different capacitors can sound very good depending on personal taste, preferences and application.

  I myself have used the Jensen Oil Caps in my tube amp mods and found the presentation to be very smooth and seductive. To the point where I could live with them in my application for a long time.
  I do not find one any "better" than the other but I do, however,  prefer the AuriCaps in my personal tube equipment. This is based mostly on customer preferences but also my personal view.

  My next test will be to install both the Jensens and AuriCaps in my reference speakers to evaluate the difference in this application. I may try this in my Meadowlark Swifts also as they already contain AuriCaps and all I would have to do is swap them out for the Jensens. Being a simple 1st order x-over design, I think this may be the best way to evaluate a capacitor in a speaker, nothing else to stand in the way.


Jensen Copper Foil In Oil Capacitors
« Reply #5 on: 6 Aug 2003, 03:09 am »
Gentlemen. . .

I am wondering if these caps may do well in a solid state preamp.

That's mine, and I don't know what I'd replace if I modded it. .



Jensen Copper Foil In Oil Capacitors
« Reply #6 on: 6 Aug 2003, 02:16 pm »
i can only see 3 caps in this shot... 3 largish electrolytics...

with polypropylene or polyester or if you can afford it paper :P
same value capacitance and they will have to be higher volatage - but those type always are just about.


Jensen Copper Foil In Oil Capacitors
« Reply #7 on: 6 Aug 2003, 02:18 pm »
oh yeah and on the front there are some smaller electrolytics
replace those for
polypropylene polyester or paper too and you should see improvements

very electronic looking pre you have there - crap all that isnt an ic by the looks.... is it any good as it is?


Jensen Copper Foil In Oil Capacitors
« Reply #8 on: 6 Aug 2003, 02:43 pm »
Well, I like it!  I think it could have a bit more sweetness, but as it is, it beats up on my old preamp.  It's a McIntosh C-41.  I am a bit scared about modding it b/c I know it will still be playing when I am long gone just by virtue of being a McIntosh.  I am not sure if they will gripe about new caps in a warranty situation. . .


Jensen Copper Foil In Oil Capacitors
« Reply #9 on: 7 Aug 2003, 12:12 am »
hehe so a 'top' company like mcintosh use some crappy electrolytics in their gear... geeez

now i know why i build everything myself... cut corner bastards!

well when the warrenty dies on it it will probably be time to replace those caps - they have a useful life of 5 years or so... then they degrade - after 20 years they will die properly. :P