Audio Research VT100 MKIII Tube Replacement

I’m confused by the question
Are you trying to replace 6550 with 6H30? Or asking if there is a difference between the 6h30 and 6h30pi?

Fwiw all 6h30 tubes are the same.

You need to order the correct valves first, two sets of SIX. Not 12 singles or 6 pairs, or 3 sets or quads.. 

If the manufacture has options for different valves, they will be listed.
KT88, and 6550 usually can be interchanged.

No, they are not the same and certainly don't sound the same..

The small valves need to be balanced also..

Read then BUY, OP.. Save you a lot of money in the long run..

Have fun, be careful, and DON'T break off the index locator, pulling or swapping valves.. BE aware.. Be Careful..

Thank you for your fast response. Database of Audio Research says; VT100 MKIII: (4 matched pairs) 6550C power output, (4) 6H30 driver. I have ordered 4 matched pairs of 6550 tungsol however I am not sure about 6H30s. I wonder what are the difference between 6H30 and 6H30Pi.
Thanks !

Cribbed from the Upscale Audio site:
"There are two types of 6H30 tubes currently being produced. The Sovtek brand which have the chrome pins (listed here), and the Electro Harmonix Gold pin. They are the same tube from the same factory. Don’t get your panties in a bunch over which is better, as the gold plating is laid over the chrome plating. They are both terrific. "

It's a stereo? To save money that is a way to do it. At the time 6 matched valves vs pairs was a lot more expensive.. Not now... To many NEW production valves out there at really good prices.. BUT I'm sure it is a way that works well for their units.. 

After 55 yeas of valves.. I match valves per rail.. pretty simple.

The signal valves you're stuck.. No idea WHY people use valves like that.. Very limited valve manufactures too.. I call it the TV tube mentality. LOL what do I do with these old TV valves.. I know, I'll voice a power amp.. No idea why.. BUT I got 12,000 of them in a container for 50.00 usd.. Cary does the same weird stuff.. 12BH7, I mean WTF is that..
12AX7, 6922, 12AZ7, but 12BH7.. TV TUBE.. 

Regards..

Pretty sure the MK III is easier to bias than the MK I and II models but I’d take it to a qualified tech as the VT100 is a bear to setup. Not to scare you but I’m sure you don’t want to blow your amp up. Unless ARC did something different to the circuit you have to bias both the input and output. I’d call and talk to ARC before you pop the lid. Definitely not an amp for a newbie to bias. Good luck.

mk3 easier to bias than earlier versions - still need multimeter and hook probes (and the long blade screwdriver)... but that is the power tubes

to bias the input tubes is tough... best to send to factory as much as a pain and major cost that may be... good news is once done the small signal tubes will be good for years and years

and to the earlier point... +1 yes 6h30's all the same...

I send my VTM200's in to AR every so many years.  They take care of everything.  Excellent service gets best performance.