MHDT Orchid TUBE ROLLING

I considered the garage 1217 adapter 5670 to 6922 couple months ago. I also hear some using a 5670 to 6sn7 adapter. Anyone try the 6sn7 in the MHDT. I have a lot of 6922’s but even more of the 6sn7’s. I’m going to order the 6922 and 6sn7 adapter after reading this and see what happens, hopefully nothing is going to burst into flames.

nothing will burst into flames... the 6sn7 adapter from garage 1217 is a quality piece, and it is fun to try many 6sn7 variants old and new... lovely sound, very airy, can roll tubes to achieve euphonic coloration or drive and transparency

significantly more variation is sq from various 6sn7’s than 6dj8s (via that adapter) and much more than 2c51/5670’s which has a narrow field of choice

just know that in all these tubes, we are talking dual triodes in a single tube - each channel runs though one side of the tube, so reasonable internal triode balance is important

I just ordered the adaptor from garage1217.
Do you think this tube will be ok?

https://www.thevalvestore.com.au/home/77-6n23p-ev.html?search_query=Soviet+reflector&results=14

that russian tube will give a spotlit treble, a recessed midrange and decent bass in a mhdt dac, i personally think it hurts the sound in the midrange, where the dac should really shine

i would suggest an old stock european 6dj8 equivalent tube from tungsram/hungary or ei/yugo if you are trying to stay at a reasonable cost (otherwise go for mazda telefunken or dutch amperex ones which are $$), these will give a nice lively treble but the midrange will be much more textured and palpable

one other important note... the g1217 adapters have long pins... do NOT insert them ALL the way into the mhdt tube socket, or the adapter pins may damage the underlying socket solder joints ... ask me how i know  :(  -- instead, look at the pin length of the stock 5670 tube and insert the adapter socket only that far into the mhdt dac tube socket

Hi jjss49

How do you know how the Russian tube would sound? Is that from experience with one, or from someone else’s review, or is there a "way to tell" ?

i have it here, have listened to it - it is the only way to know, for sure

i have many pieces of gear that run 6dj8 equivalents... i have quite a collection of these tubes (~200 accumulated over the years), probably 15-20 different makes and variants... and have listened to most if not all of them all over time

6922 on top of converter will go through the cut out of the top plate... unlike the 6sn7 whose diameter is larger than the hole in the top plate, thus running that tube w converyer you need to run without top plate or enlarge the hole

but the 6922 with converter plug will sit tall, will protrude up far above the level of the top plate by 2/3 of the glass envelope of the tube

garage1217 makes far superior adapters than those chinese units 

with 6dj8 and 6sn7 adapters for the mhdt units, one has a very very broad range of tube choices to roll, and both tube types have long illustrious histories and were made in various parts of the world to boot

you will get somewhat lower gain from some variants(esp. older 6sn7s), but since the tube is used as an output buffer only, that will not impact the dac's output voltage too much

for all tube rollers of orchids, stockholms, istanbuls and the like, just be careful -- be very gentle and use a steady and firm hand when removing the tube from the adapter, find the right orientation where gentle rocking pressure will loosen and release the tube pins, and especially when releasing the adapter from the socket on the dac's pcb board... the board is somewhat flexy and there are examples of folks breaking connections between the tube socket and the board below - jian at mhdt has been cool about sending replacement boards in the past, but one cannot count on his goodwill being extended indefinitely