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Hi
I bought an Oktava MKL5000 and it was complete crap so the seller replaced it. The new one was ok, but the noise performance was not as good as I had hoped, so I decided to mess around with different valves. What really surprised me was how different each valve sounded.

I tried Mullard EF95s, and while they were too noisey, the sound was very rich and full.

I then tried a Haltron 6AK5 which was quiet but the sound was very thin.

Today I got some old Soviet military 6X1Pis from Ukraine and the sound is again completely different.

Now these valves are all compatible with each other, but what surprised me was that the Mullards were different from each other, and each of the ex-Soviet valves is different.

I wonder if anyone here has tried out different valves on their mics, and if so, how big was the difference?

Thanks

John Stafford

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Comments

TeddyG Sat, 04/02/2005 - 08:59

Most of these tubes are old - very old - 30+ years old... With the exception of the currently-made Chinese or Russian tubes - all of which are said to be of sometimes questionable quality, even brand new?

That said, a NOS(New Old Stock), or carefully tested, used, RCA, might be a good choice? Never considered to be "the best" tube for critical audio, perse, it's still a very consistent tube, a nice tube one to the next. The RCA's are also among the lesser-priced, as there were just so darn many made. Again though, not for many years - and even tubes have "lifetimes", used or not.

TG

jonyoung Sat, 04/02/2005 - 09:22

I swapped out tubes in an ART Pro MPA and was also astounded at the difference. I'm looking to buy a 2nd one so I can have a pair of 12AX7 channels and a pair of 12DF7 channels (great warm sound for vocals). I got NOS Sylvania and Westinghouse form this site:
http://www.vacuumtubes.com

He has really good descriptions of what the original applications were for each model, but will not make any recommendations. I agree with TeddyG that NOS is the way to go. If they don't have any mileage on 'em, they won't leak any oil!

Cucco Sun, 04/03/2005 - 07:27

Agreed - NOS is a great way to go.

Personally, I did Groove Tubes' stuff. Some of their stuff is NOS, some is new. All of it is rebranded (I believe.) In other words, they select from the finest tubes they can find and then slap their names on them. Whatever the case, it's quite common to find some very good tubes from them and they are usually pretty close in sonic character.

Try the gold series.

J.