Comparison of ET7 Series 1 & 2 and Act 2 Series 2

[roberto]

Yes agreed Roberto mate, thanks for sharing your info, and I've come across these indicators before. As you pointed out correctly different names /types across different countries of origin do have similar specs and some don't, hence the very reason why we need to do careful matching...

Also, what I was wanting to know specifically is whether the 6922/e88cc tube is a direct replacement to the Phillips 7DJ tube that is used in the ET7S2 and GATS2?

This chap did the swap on his ET7 series 1 and the LP275m monoblocks but it didn't work out... why I wanted to check?
In terms of output tubes there were no issues, replacing the 6550c tubes with KT120's was marvelous! But not the case in the input and driver/phase inverter tubes... that is still perplexing.

He sent a note to his Spore dealer and they confirmed not to swap these tubes as they are quite different in values and spec. He wanted to double check with CJ but no reply as yet since he purchased these items used, I don't think CJ has time to reply to every question they're asked.

Let me know what else you advice for these direct replacements. Thanks, RJ

Hola RJ,

Sometimes, when we change a tube, for a new one, we think that it is going to work, but perhaps not. Even being new, it might comes with a problem. It is wise, if you have a problem, change it again...believe, I had recently on a power amp, I did change four 6922...or they were noisy, or one channel was making fireworks. I thought also, that these tubes were new, and I can not assure that. At last, one tube was OK. All of them were different brands and the last one was a Genalex Gold Lion. I could not believe that I did use all that tubes. Of course they are into the trash right now. Many people keep bad tubes. I think that a bad tube must be throw to the basket right away. All bad tubes belonged to him, and mine was the only that worked right (Gold Lion).

Tubes are very temperamental. A day could be dead free of noise, clean, and the next day we could have fireworks. You do never know this. But this is a minor flaws for the benefits of their sound quality. A reason that I am always advising to you to have a pot next to you. This pot, put every time you listen to the music, at least $ 2.00. This is your fee for the quality sound of your system. When you need money for a tube change, at the pot you will have plenty money to spend on new tubes.

Regarding the 6550s and the KT120s, they can be replaced direct with no issues. Keep in mind that when you use a KT-120, you have more power dissipation. If you replace the KT120s by 6550s, would be a step down.



The 6DJ8 / ECC88 / 6922
Filament Voltage 6.3 V
Filament Current 365 mA
Plate Voltage (max) 130 V
Plate Current (max) 25 mA
Plate Dissipation (max) 1.8 W

Usually the first number on a tube, indicates the filament working voltage. Here is a better explanation about the nomenclature at the tubes

http://www.duncanamps.com/technical/tubenumber.html

Happy listening!

[Big Dog RJ]

Thanks for the info Roberto.

I'm well aware of the changes in output tubes, swapping 6550's with KT120's. In fact, if an amplifier uses 6550's, as long as the transformers are up to spec, you can directly replace the whole line up: KT88, KT90, KT120, also several versions of 6550 type C, winged C, type A and so on. The only ones you cannot swap are the EL34 and KT150, although some people have had success in changing from KT120's to KT150 on their Jadis amplifiers. I've done these changes myself and so far no issues.

But that's not what I'm asking mate,

I'm talking about the specific 7DJ8 tube that is used in the ET7S2 and GATS2. Can this tube be swapped for a 6922/E88CC?

From what I've heard on the amps, he was running LP275M's and the ET7 series 1, all fitted with this NOS 7DJ8, you cannot swap these tubes from a 6922. It's slightly different and requires internal adjustments.

However, I wanted to know if any other forum members experienced this same thing or even attempted to change their 6922 to 7DJ8, and if so we're there any issues...?

I'm heading to this chaps place over on next Friday, we're trying it out again to see what the causes of the hum are. According to my long time trusted tech and main importer of CJ for Aus, he definitely confirmed it is not a direct replacement without internal adjustments, and I believe him hence this is what's causing the unwanted hum...

If you come across anything else let me know.
Thanks Roberto mate, RJ

[roberto]

RJ,
The filament voltage on a first digit is 6 is 6 Volts, on 7 is 7 volts on a 12 is a 12 volts...there are specific instructions for other nomenclature filament voltages there.

Happy listening

[roberto]

RJ,

Here you can do a comparison between the KT150 and the KT120

https://www.tungsol.com/html/kt150-tung-sol.html
http://www.tungsol.com/tungsol/specs/kt ... curves.pdf

If you look, there are a lot of different variables, and also there are some that look similar. Of course the 150 is a bigger tube, offering 70 Watts of plate dissipation, 10 watts more than the KT120. Jeff recommends do not change a KT 120 for a KT150 on CJ power amps. He must have the reason why not.

Happy listening!

[roberto]

RJ,

..." From what I've heard on the amps, he was running LP275M's and the ET7 series 1, all fitted with this NOS 7DJ8, you cannot swap these tubes from a 6922. It's slightly different and requires internal adjustments "...

The power supply is designed for this tube with a 7, not a six. People are saying the CJ is a tube eater...if you change the specifications, and use a 6 filament volts where a 7 Volts is the right, of course the filament is going to suffer.

Right on my dear JR...

Happy listening!

[Big Dog RJ]

Correct mate!

This is the point I was making. So those amplifiers using the 6922/E88CC cannot directly replace this type with a 7DJ8 tube, unless things were slightly modded.

Hence, the very reason why the excessive hum, especially being further amplified from the big LP275m monoblocks...
CJ finally got back to us, it's definitely a no go, although at times you may get away with it, in the long term other unwanted issues will occur.

The Phillips 7DJ8 is a unique NOS tube that CJ has plenty of stock and is now offering on it's latest series 2 preamplifiers, the ET7S2 & GATS2, these preamps are truly special in every sense of the term in preamplifiers.

OpenD will have a superb musical experience, owning both the Classic 120se partnered with this beauty. I think now, all you require D is the cherry on top! The TEA2se...

Cheers mate, have a good one.
Best, RJ

[roberto]

Hola Chicos,

As a general rule, my advice to you is: use ONLY the tubes that in your Conrad Johnson operation manual states. Your preamp or power amp have being design taking in much care the tube's specifications. The design circuit has being carefully optimized for that particular tube number. You can do some tube rolling, but always keeping that number. American number is different than the European number, as an example : 6922/E88CC is the same tube. The 7025/12AX7 also is the same tube.

On the tube marketplace, you can buy tubes from different manufactures. There are all kind of prices. Their price sometimes the most expensive does not means that they do sound better.

The other advice is: if your ears like it, then keep it that way!

Happy listening!

[roger]

My friends roberto/RJ,
So are we saying that changing the input drive from EH(6922) to Philips PCC88 on the art 150 might cause a problem? I just emailed CJ to ask the same question as well and hope to get some response from them soon. I did two 3-4 hours session over the weekend and interesting enough the high frequency hissing during the first dew minutes were gone. Any thought?

Thanks
Roger

[roberto]

Hola Roger,

The tube that you want to change is a 7DJ8, right? You can not use the 6922/E88CC for tube rolling. The the first 7 digit means the heater voltage. The 7 indicates 7 Volts. The E88CC/6922 is 6V. That 1 volt in difference in a heater is very important. You can not use a 6 volts tube where the design is for a heater of 7 Volts.

Happy listening!

[roger]

Hola Roger,

The tube that you want to change is a 7DJ8, right? You can not use the 6922/E88CC for tube rolling. The the first 7 digit means the heater voltage. The 7 indicates 7 Volts. The E88CC/6922 is 6V. That 1 volt in difference in a heater is very important. You can not use a 6 volts tube where the design is for a heater of 7 Volts.

Happy listening!

My friend roberto,
Yeah you are right. I overlook when I shopped for Philips because it says something like this: https://www.ebay.com/itm/PCC88-7DJ8-PHI ... 0746635558 so I thought 6922(7DJ8) and PCC88(E88CC) are compatible for tube rolling. I should change change back to 6922 that comes originally.

[roger]

Hola Roger,

The tube that you want to change is a 7DJ8, right? You can not use the 6922/E88CC for tube rolling. The the first 7 digit means the heater voltage. The 7 indicates 7 Volts. The E88CC/6922 is 6V. That 1 volt in difference in a heater is very important. You can not use a 6 volts tube where the design is for a heater of 7 Volts.

Happy listening!

My friend roberto,
Yeah you are right. I overlook when I shopped for Philips because it says something like this: https://www.ebay.com/itm/PCC88-7DJ8-PHI ... 0746635558 so I thought 6922(7DJ8) and PCC88(E88CC) are compatible for tube rolling. I should change change back to 6922 that comes originally.

So correction, the input drive for art 150 is 6DJ8 not 7DJ8... so I guess after all it's interchangeable.

[roberto]

Hola Roger,

Yes, if the amp comes with a 6922, the 6DJ8 is the same...
Try to use what the factory recommends. You can't go wrong with it.

Happy listening!

[roger]

My friend roberto,
So CJ did get back to me and confirmed on the compatibility for Philips PCC88(same one used in ET7S2) in ART150.

[roberto]

Roger,

Those are great news...enjoy your tube rolling. Just keep in mind the tube numbers. The first digit is the working voltage. They should be similar.

Happy listening!

[roger]

Roger,

Those are great news...enjoy your tube rolling. Just keep in mind the tube numbers. The first digit is the working voltage. They should be similar.

Happy listening!

roberto,
Thanks again for your detailed explanation on the tube specs! I am glad as well that the tube swapping will not cause issues as I really like how it sounds with the Philips.

[roberto]

Roger,

Philips made in Holland is one the best sounding tubes that I ever heard. I had some issues with them, but nothing to be worried about it. I got left channel with odd sounds sometimes or hissing. I ended with Genalex Gold Lion. This what I am using now. I really like what I am hearing.

Happy listening!

[roger]

Roger,

Philips made in Holland is one the best sounding tubes that I ever heard. I had some issues with them, but nothing to be worried about it. I got left channel with odd sounds sometimes or hissing. I ended with Genalex Gold Lion. This what I am using now. I really like what I am hearing.

Happy listening!

Hola roberto,
Yes I do like the sound very much on Philips. CJ also recommend GOld Lion and that's what I will get next to try on.

[roberto]

Roger,

My perceptions on the Gold Lion are:
1) Dead quiet. The signal to noise ratio improved.
2) Strings are not so sweet as are on the Philips E88CC, but are better detailed with much definition.
3) The metals are projected with incredible dynamic and air between the musical instruments
4) Voices are presented with a realism that you really feel they are there. There is no soreness on their throats.
5) The stage is wide and a truly sense of 3D. Perhaps the Philips is better here, but almost identical.
6) You get the fun that the musician(s) are having.
7) Bass notes are well defined, and allow to you to understand what the bass player is doing at the fret neck or at the fingerboard.
8) Both are great tubes. I could live without hesitation, the Philips or the Genalex.
9) My speakers are very demanding with the quality at the mid range. Here, both tubes shines with no problem at all.
10) The highs are crystal clear and the timbre of the musical instruments on both are granted easily.

Happy listening!

[roger]

Roger,

My perceptions on the Gold Lion are:
1) Dead quiet. The signal to noise ratio improved.
2) Strings are not so sweet as are on the Philips E88CC, but are better detailed with much definition.
3) The metals are projected with incredible dynamic and air between the musical instruments
4) Voices are presented with a realism that you really feel they are there. There is no soreness on their throats.
5) The stage is wide and a truly sense of 3D. Perhaps the Philips is better here, but almost identical.
6) You get the fun that the musician(s) are having.
7) Bass notes are well defined, and allow to you to understand what the bass player is doing at the fret neck or at the fingerboard.
8) Both are great tubes. I could live without hesitation, the Philips or the Genalex.
9) My speakers are very demanding with the quality at the mid range. Here, both tubes shines with no problem at all.
10) The highs are crystal clear and the timbre of the musical instruments on both are granted easily.

Happy listening!

roberto,
Thanks again for the detailed comparison. I definitely think the Gold Lion would be my shopping list of tubes to get now. Part of fun on tube equipment is the enjoyment of getting different characteristics from tube rolling and appreciate at your sharing on the experiences on this!

[roberto]

Roger,
With much pleasure!
Happy listening!