Jadis DA88s: tube matching

I have a Jadis DA88s integrated amplifier, and it uses four power tubes for each channel. In the past ten years, I bought more than 15 NOS Mullard EL34 tubes (XF2, OO getter) for the amplifier. Since it is hard to find a matched quad for each channel, can I use two matched pairs instead?

"The design is a huge factor. Plate voltages, screen voltages, and bias voltages are key. Some amp designs run the tubes very hot, which tends to shorten life."

from this

If you are needing that many replacement tubes, that amp, and the bias setting, is a problem IMO.

and, NOS assumptions need to be considered.


Tubes are supposed to last for YEARS.

Are you in a hurry? I suggest you buy a full set of cheap used tubes, so, for the rest of your life, you don’t live without music, while searching/deciding on the next set you will use. Time is a luxury, time for research, find most comfortable source, wait for a great price .....

2 matched pairs?

from your stock? or buy from a source with matched pairs ready to ship?

If they have matched pairs, they have a tester. Perhaps, for a small premium, they will test and find two pairs for you, if you can wait.

Ignoring all the other electrical measurements, for me, it comes down to left/right balance.

I just lost left channel, was a blown 6sl7. Happily, when I searched my boxes of randomly acquired tubes, I had two GE 6sl7’s, used, in my collection. I replaced the blown one, oh happy day, and, l/r balance was terrific. Time to search ....

GE 6sl7 is short, so, I decided, while waiting for the two matched pairs I ordered, to put the other short GE in right channel. Nooo, right channel volume way down. Original tall one back in, l/r equal. No way a matched pair, but ..... especially temporarily.

btw, I had 4 look alikes, 2 6sl7 and 2 6sn7. preamp tubes before KT88’s. I mixed them up inadvertently not long ago, left channel was weak, yanked for testing, realized they were different. They look identical. I purposely ordered chrome top 6sl7’s so I will never mix them up with the 6sn7’s.

I have my own tube testers. The little cheapo one always gives the same relative strength answers as the big one.

not to buy this one, but this is the model


I love this little thing.