MHDT Orchid with WE 396A Unbalanced

Hi everyone.

I recently picked up a used MHDT Orchid from Canuck audiomart. But I am yet to listen to it as my Tannoy MG15 in under refurbishment and I don't have anything else to listen it on. Orchid came with 4 tubes:

1) GE JAN 5670W NOS

2) Some 5670 made in USSR

I got the next 2 tested and they were found to be unbalanced.

3) WE 396A

Triode a -93℅ at 100v
Triode b-84℅ at 100v 

4) Siemens Halske CCA 88 with adapter.

Triode a -93℅ at 100v
Triode b-84℅ at 100v 

What do these measurements mean. Can they be used in the Orchid? Will an unbalanced tube cause any problem in the dac. Looking for guidance .



I own the Orchid DAC and use it regularly.

The GE JAN 5670W tube is the standard tube that came with the DAC.

The WE 396A was an upgrade tube option that a few years ago cost about $75 but I noticed now this tube is selling for 2x to 3x times that. The WE 396A is highly praised. Give it a listen.

Don't understand you questions about the measurements or that they are unbalanced. You might want to post those questions on a tube forum.

The WE 396A tube turned out be defective, only one channel is working. Rest of the tubes are working fine.


I have an Orchid and preferred the 6922  with adapter to the 5670.  The 7311 seemed to extend the top end for me while the NOS bugle boy D getters sure were nice. 

As good as the DAC is I replaced it with PSAudio DirectStream DAC.  It should be better it cost almost 5X the price of the Orchid new.

I did not do the GrannyRing capacitor and resister upgrade but still have it so it would be fun to try it and see how it compares.  Of course their is the DirectStream MK1 upgrade that is supposed to take it to the next level....

AHHH what a hobby.


first of all the somewhat imbalanced test readings on those tubes are nothing to worry about... in the mhdt dacs the tubes are in a buffer circuit at the output, so the tubes are run very easy and well within their comfortable operating limits, and so the minor transconductance (effective gain) differences across the two triodes at a narrow tube tester test frequency will be barely heard (if at all)

second, you should try the various tubes and see which you like best, i have found the we 2c51 adds more high end sparkle and air, which is a nice upgrade for some systems

third, in my experience (i have had 5 mdht dacs, including the stock and grannyring modded orchids) using a good 6sn7 or 6dj8 adapter opens up a much wider field of tube choices, my favorites are rca 6sn7’s (greater spaciousness and drive) and the amperex 6dj8 (same, with a nice spotlit midrange clarity)

the fun is in the tube rolling, so enjoy the learning experience!