Our Next “Tube Adventure” with the ECC88 / 6DJ8 and E88CC / 6922

In our next Tube Adventure we were looking for an even more favorable sounding tube.

I found a tube that was almost compatible in terms of electrical characteristics, the ECC88/6DJ8, with a heater voltage/current of 6.3V/365 mA, and an amplification factor (μ) of 33.

This was similar to the 5670, 396A, heater voltage/current of 6.3V/350 mA, and an amplification factor (μ) of 35.

In other words, the ECC88/6DJ8 can be said to be a little bit less powerful tubes, but the only way to find out how much leeway the U4's heater and plate power supply had was to actually replace them.

However, unfortunately, the pin arrangement of the socket was different, so it was not possible to replace it easily.

Still, there may have been some luck, as I was able to find and obtain a socket adapter on eBay that fit the ECC88 pin arrangement.

The first ECC88 tube I acquired was made by Philips, the manufacturer that developed this tube, and was made in the Netherlands.

The sound was not flashy, but calm and spacious, and I found myself enjoying the music in a more relaxed manner, perhaps more like in a natural reality.

Encouraged by this positive result, I was able to collect various kinds of E88CC/6922 tubes (highly reliable versions of the ECC88) within a short period of time, and was able to enjoy and confirm each sound character of these tubes.

Of course, I asked my good friend, Nishikawa-san to listen to three types of ECC88-type sounds, and he gave me this impression:

“First of all, compared to the WE 396A before replacing it with the ECC 88 types, all three types of ECC88 or E88CC tubes improve the smoothness of the voice and strings. I also felt a common difference in the spacious sound stage and the beautiful, relaxed sound. But of course, each of the three tubes have their own characteristics:" 

"The Philips ECC88 / 6DJ8 (made in Holland) has a smooth and unobtrusive character with voices and strings, making it relaxing to listen to." 

"The Amperex (Philips) E88CC / 6922 (made in the USA) lends a bright, carefree, and open feel to the sound."

"The Mullard E88CC / 6922 (made in the UK) has a lower center of gravity and a thicker voice, giving it a sense of realism and pleasant dignity."

"Anyways, it would be very interesting to hear the national characteristics reflected in the sound of these mini triodes. All of them are wonderful, but personally, I like the Mullard best because of the thickness of the chest in the voice and the resonance of the body of the strings. The texture was very natural and the quality was good." 

"After listening to these three tubes, I replaced them with the WE 396A and listened again. The WE 396A has an attractive and unique mid-low range and the sense of the proper distances between each sound image. It also has some negative points, a lack of smoothness, or roughness, on vocals, and the narrowness of the sound field. However, I don't think I was able to notice such differences unless I replaced it with the three tubes mentioned above. I don't think you will be able to hear those differences if you listen at a low volume.”

I felt much the same way as Nishikawa-san. And I have thought that the more relaxed low range and richer sound field of ECC88 and E88CC compared to RCA5670 and WE396A are qualitatively due to the difference in plate resistance (Rp) of each type of tubes (5670; 6400 ohm, ECC88; 3900 ohm).

This is because the Rp is the internal resistance of each tube and is also the substantive output impedance.

When considering the driving power for the next stage, it goes without saying that it is desirable to have the smaller output impedance.

Anyways, this is how I have continued my Tube Adventure, and my favorite tubes so far are those made in the UK, the NOS Mullard and Brimar E88CC, with their smooth high range and glossy and elegant tone would be superior to the other brand tubes.

Both are really great tubes, but the Mullard E88CC's flawless, high-quality sound with no weakness to be found is certainly hard to ignore.

However, if anything, I like Brimar's more delicate and attractive expression of nuance in the high range. Of course, that's only my personal liking.

In any case, it seems that there are still quite a few of these vintage tubes on the market, and isn't it wonderful for us to be able to enjoy such a great and true legacy from the past, more than a half century later?

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