EF86 Preamp Tube Comparison: JJ vs RFT

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EF86 Preamp Tube Comparison: JJ vs RFT

Postby JMPGuitars » Sun 09/29/13 9:15 pm

Out of sheer curiosity, and love for the EF86 as a preamp tube, I recorded a comparison between the JJ EF806S (modern EF86 from JJ) and an RFT EF86 (NOS).

I haven't had much trouble with microphonics, but I did actually hear them from the JJ version at one point. I added rubber grommets to the tube socket mount, and haven't heard much since while playing. I did a little research and the RFT EF86 is said to have extremely low microphonics, and great tone. So here's the comparison video...

In the first part, it's pretty clear that the JJ tube is significantly more susceptible to microphonics. You can hear them coming through almost anywhere I tap on the chassis. With the RFT tube, only hard tapping on the tube, and really close to it came through the speaker at all. Anywhere else on the chassis wasn't an issue like it was with the JJ.

As far as tone goes, take a look and decide for yourself. I recorded this while testing output tubes, and used the Tung Sol tubes for output and swapped out the EF86 after finishing that comparison. I recorded the demo with an open chassis sitting directly on top of a closed-back cabinet, which is essentially the worst thing to do if you're trying to avoid microphonics. I figure if it performs well in a bad arrangement, it should be fantastic mounted properly in a cabinet.

Here's the video: http://youtu.be/l7uxYW7H1jw

Let me know what you think!
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Re: EF86 Preamp Tube Comparison: JJ vs RFT

Postby Wayne_Alexander » Tue 10/01/13 7:33 pm

As is the case with my listening to the power tubes, over my crappy computer speakers, there don't seem to be drastic tonal differences. Was there more evident contrast when listening live?
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Re: EF86 Preamp Tube Comparison: JJ vs RFT

Postby JMPGuitars » Tue 10/01/13 8:34 pm

Wayne_Alexander wrote:As is the case with my listening to the power tubes, over my crappy computer speakers, there don't seem to be drastic tonal differences. Was there more evident contrast when listening live?
I thought they both sounded great, and I would again suggest using headphones. The HUGE difference was in microphonic sensitivity. The RFT was by far superior.

Even on the computer speakers you should be able to hear the difference when I tap the chassis. The high-pitch echo of each tap with the JJ tube is coming through the amp, but when I tap with the RFT tube in, you only hear it through the camera mic, not the amp. (except for really really close to the tube).
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Re: EF86 Preamp Tube Comparison: JJ vs RFT

Postby Wayne_Alexander » Wed 10/02/13 3:16 pm

I heard the microphonic tap test well. I was referring to the tone/playing tests.
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Re: EF86 Preamp Tube Comparison: JJ vs RFT

Postby JMPGuitars » Wed 10/02/13 4:20 pm

Wayne_Alexander wrote:I heard the microphonic tap test well. I was referring to the tone/playing tests.
Cool. Listen with some decent headphones and you should get a better idea. To be honest, I didn't hear a huge difference in the short period that I did the test, they both sounded great. I was really after lower microphonics, so the fact that I didn't hear a huge difference in tone was a good thing, since I think they both sound so good.

I built an EF86 18 Watt Combo with Reverb, so lower microphonics was a must. I'll post a demo video of that soon, but you can see photos of it in my gallery.
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