Test Reports and Reviews of

jb JFX Premium Metallized Polypropylene Capacitors



Test report from an Audiophile in France (Mr. SAM BENELBAZ )


Samples tested by Mr. SAM BENELBAZ

jb JFX—premium metallized polypropylene film capacitors

jb JFX 94uF 250VDC +/-5% Bulk RoHS 2pcs

jb JFX 22uF 250VDC +/-5% Bulk RoHS  2pcs

jb JFX 3.5uF 250VDC +/-5% Bulk RoHS  4pcs


Introduction of Mr. SAM BENELBAZ

French, retired, have the hobby of TUBE do it yourself; used to work in IBM as a professional of electronics; after that for LASER a company involved in point of sales solutions and hardware maintenance, in that position, he bought a French company sic-safco.

Mr. SAM BENELBAZ is member of some forums in US and France, some are AUDIOASYLUM.com, DIYAUDIO.com,  FUN WITHTUBES.com and some others.


Original letter from Mr. SAM BENELBAZ

Dear Iris,
I hope you are ok.
I have installed the JFX capacitors last Sunday and i can now give you my impressions.

But first I have to tell you what speakers and amps I used for the test:

The speakers are YAMAHA NS
1000M well known in the market and very revealing .
The amps are two American CARY tube amps model
40M using 6SL7 and EL34 tubes.
In this test the EL34 are NOS Philips EL34 of the XF2 series (the best).

The Yamaha crossover was using mainly NICHICON capacitors using metalised paper.
I did replace every capacitor with the ones you send me.

The CDs I use for the test are very good Cds , classic music and jazz mainly.
I know them very well and can hear the differences well.

Now lets come to the findings:
The JFX have good audio imaging and you can hear obviously more details than with the Nichicon .
I think this is because they are wounded very tight.
Congratulations to the worker who did the job.
At this very moment i think that JFX are very good capacitors for crossovers and with their price-sound ratio you can go to the market without any shame.

My best regards



Reporting back on these JB JFX caps and they are wonderful folks. I can't say it more clearly. They compete with any cap and I don't care of the cost.

I have used them in two different preamps and one amp…. all tubed units. I used them as coupling caps with great results.

They are sleepers are dirt cheap.


05-01-13 Grannyring post on AUDIOGON Forum



One needs to understand I compared all of theses, except the Duelands, in
the power conditioner. I mixed, matched, & rotated these 'dogs' over several months time. As I came to understand the tonal inflections &
character each brought to the filter/feeding of the digital, preamp, & amp
sections, I simply feel S/G/O 'plays well' on digital sources. It's a great cap. Killer vocals. Great soundstage. The JFXs take that & send it out via pre & amp w/aplomb. Now the Duelands may do that ever more so, but I already owned the Mundorfs & the JFXs size & cost made an easy choice for the larger values. They have an incisive spacious sound w/very good attack & decay, require little break in & represent exceptional value.


06-26-13 Regismc post on AUDIOGON Forum



Ok gang, I have been using a cap that is so good that I'm afraid when you hear the price most will disregard my comments. Keep in mind I compared it to the best - Duelund CAST copper.

This cap came very close to the CAST and offers a richer sound it is also more expansive sounding. The bass is more full bodied. It lacks the ultimate degree of detail of the Duelund. The Duelund is a tad more resolving and in the end is still the king. However, you must try this cap out as you will be amazed. I would use it ahead of any Mundorf as well as most every other cap aside of CAST.

It is my cap of choice based on sound quality and price. I have only tried it in tube amps and preamps mind you.

They cost under $10 for values under 7uf. Yes, this cheap and darn good. Yes, metalized film.....Yes, it still is this good.....

Several other Audiophiles have heard them and also agree 100%.

You can get them at Just Radios in Canada. They are Chinese made. Don't worry about that either as they sound great.

Oh yes the name ......JB JFX Premium caps.

04-11-13 Grannyring post on AUDIOGON Forum



"During the last 25 years, I've used MIT, Relcaps under various company names, Mundorfs, The jb JFX caps are better than the others.”
Paul Weitzel of Tube Research Labs

“The jb JFX capacitor is a fine capacitor with a high quality build, and competes well with the Erse capacitor."
Mr. Steven of PranaFidelity

"I must tell you that this is my second order of JFX caps from you which I am using in parallel to bypass power caps in a tube amplifier. The results are staggeringly good, hence my second order. JFX capacitors are without doubt on my 'best buy' list for audiophile quality caps. I sincerely appreciate you stocking these."
Dan L. from WA/USA

JB JFX Caps: Has anyone heard of this cap? I was buying parts for a tube amp from Just Radios and saw they were selling these caps. I did a google search and found one post from a guy on Audiogon that really liked them. I was working on a pair of Bozak B201s at the time, so I added a pair of 4.7uf to my order. I was very impressed with how they sounded in the Bozaks so I bought a pair of 5.6uf to try in my SDA 1BTLs. I have been running Clarity PX caps which I thought sounded good, but after letting these break in, I"m really impressed with them. They definetly have better detail than the Clarity caps and are just as smooth. For the price these caps are hard to beat.
bigaltx24 post on Polk Forum 04-13-2014
JFX reviews from Sales Dept:
I am writing to let you know that I have tested the performance of capacitors. The JFX serie have surprised me. I want to congratulate JB for the good work. I've installed on hifi otl tube amps and hifi otl tube radio and the sound has improved a lot. As soon as my economy allows me, I hope to make a new order.
ak1ak2ph of Israel

Your capacitors have been used in the passive filters. At high frequencies, they are very well expressed. Also compare with other capacitors. Very similar was the result of tests with some other samples. Your capacitors are superior to some well known brands. Very clean, transparent top.
from Edward in Russia

Let me first say congratulations on shaking up the “boutique” cap world with your JFX offering. I’ve specified some of your caps in my latest project, a 50W Class AB amp called Fetzilla I feel that the JFX is a solid performer in either direction used(after all it is a bipolar cap as you stated), and i feel that the price/performance ratio is excellent.
from Kristian in Sweden

My review of the capacitors JB JFX. I started using capacitors JB digging in tube microphone and lamp priampah and have never regretted. Sound without coloration, ESR = 0, price-quality ratio + + + + +. Applied capacitors JB JFX to rework kondesatornyh microphones Behringer B1, M Audio Nova sound without color natural clean. Tube microphone amplifier (priamp) which I made myself, it sounds just great with the capacitors JB JFX.
from Sergey HAM RV3SEU in Russia

After plenty of burn-in time (that they need to open-up) they deliver a wide and open sound stage. Nice and neutral, but the signature can be a bit upfront and flat. In some cases the "flat" sound can work well,They are also fine when used in parallel woofer sections or as a less critical midrange series capacitor.The price / quality ratio is very good. I can highly recommend this capacitor if you are looking for a nice, but not too expensive MKP.
from Tony in The Netherlands
jb JFX Premium Polypropylene Capacitors : Information and Features
jb JFX Specifications and Dimensions of sizes carried by JustRadios